Some of these potential mechanisms that may contribute to perforating artery occlusion, and how they might represent a possible target for therapeutic interventions, are summarized in Table 1. Lacunar infarcts are one of the distinctive markers of SVD, including both sporadic [ 16 ] and monogenic SVD types such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy CADASIL [ 48 , 49 , 50 ] and other rare hereditary diseases [ 51 ].
In histopathological studies of lacunar infarcts, the perforating arteries typically show thickening of the media, lipohyalinosis, segmental arterial disorganization, and fibrinoid degeneration [ 18 ]. However, the histopathological findings represent the end stages of the disease, and the correlations with the clinical event are difficult to establish in most cases. This discordancy could result from therapeutic advances in stroke prevention, such as hypertensive treatment, which could reduce the likelihood of presenting severe progressive stenosis of perforating arteries, while other alternative mechanisms, including embolic occlusions, might have prevailed.
However, these mechanistic interpretations are drawn from evidence obtained in post-mortem studies conducted, in most cases months or years after the clinic event, when many factors, including remodeling of the microvasculature, changes in blood flow, and antithrombotic therapies, may have altered the structural features of the small vessels. Neuroimaging of lacunar stroke has the main advantage of shortening the time from symptoms onset to examination, providing imaging with high temporospatial accuracy and offering insights on the mechanisms occurring during infarction and on the course over time in longitudinal studies.
However, imaging evidence has to be considered indirect in most cases, especially in SVD studies, as the small branches of perforating vessel are not visible, not even using high-definition MRI although the main branches may be visualized using high resolution MRI angiography at 7T [ 27 ].
Much information provided by imaging studies is difficult to generalize and depends on many factors, including different criteria to define markers in imaging, acquisition protocols, processing software, and interobserver reliability. Therefore, new markers in imaging research studies need to be tested through various steps of validation. In brief, a newly discovered marker needs a proof of concept does the marker measure a specific change related to a disease process?
The technique to assess the marker should be repeatable precision under the same operating conditions and reproducible precision under different operating conditions. Finally, the marker should be effective as an endpoint for clinical studies i.
However, only a few markers in imaging used in SVD research meet most of these validation criteria. More detailed information on the validation of imaging markers in SVD is available in the harmonizing brain imaging methods for vascular contributions to neurodegeneration HARNESS position paper [ 52 ]. Deep perforating arteries are currently considered end-terminal vascular territories that supply subcortical white matter and deep grey structures.
According to this classical theory, the occlusion of a perforating artery would irreversibly lead to infarction of the whole tissue, supplied by an occluded perforating artery within a few minutes after occlusion [ 53 ]. Perfusion studies on CT and MRI showed that small areas of hypoperfusion but not a complete absence of it are visible in some patients with a confirmed RSSI on follow-up imaging, including areas of potentially viable tissue ischemic penumbra [ 43 , 44 ], in contrast with the hypothesis of a complete flow obstruction, without compensation in a terminal arterial territory.
The capsular warning syndrome was first described in patients with lacunar stroke involving the internal capsule presenting repeated, stereotyped episodes of motor lacunar syndrome or sensorimotor lacunar syndrome, within 24—72 h, with complete recovery between episodes, which involved two of three body parts face, arm, or leg , or more, without cortical symptoms [ 56 , 57 ].
Other studies described lacunar strokes with a similar clinical stuttering course, in other anatomical regions as the pons [ 58 , 59 ]. Several mechanistic interpretations of the capsular warning syndrome have been formulated, including hemodynamic failure in the presence of a stenotic perforating artery, arteriolar vasospasm, and peri-infarct depolarization [ 56 , 60 ]. However, the fluctuating insufficiency of a residual blood flow compensation through collateral vessels from nearby perforating arteries would also be consistent with the clinical stuttering presentation.
Although perforating artery branches are not directly visible in vivo using conventional imaging, three perfusion studies, one based on CT perfusion [ 28 ] and two on MRI perfusion [ 45 , 46 ], provided similar results of indirect evidence of hemodynamical compensation, through retrograde blood flow filling centripetally the ischemic regions that evolved into a RSSI, suggesting the presence of microscopic collateral supply by a capillary network.
In few cases, the ischemic area showed an early and anterograde filling, corresponding to normal or increased perfusion, indicating the patency of the perforating artery during image acquisition, consistent with recanalization, suggesting an embolic origin of the occlusion in a minority of patients [ 28 ]. However, this technique probably has low sensitivity no gold standard is available in imaging , and specificity could be hampered by badly impaired blood—brain barrier BBB permeability and hemosiderin deposits.
Other non-conventional techniques based on high-resolution MRI for vessel wall imaging enable the detection of non-stenotic atherosclerotic plaques occluding emerging perforating arteries, despite apparently normal vascular imaging [ 19 , 62 ]. The number and morphology of the perforating arteries are also evaluable using high field MRI [ 63 ]. However, the long acquisition time and sensitivity to movement artifacts limit the feasibility of these techniques in patients with acute strokes.
In the last 20 years, many authors focused their attention on vascular and endothelial dysfunction in SVD using imaging to assess vascular function measures for BBB permeability, blood flow, and vascular stiffness [ 4 ]. The endothelial dysfunction seems to have a crucial role in the pathogenesis of SVD, involving vascular inflammatory mechanisms altering the BBB permeability and extravasation of inflammatory particles into the extracellular space, causing perivascular edema and microglial dysfunction.
Endothelial inflammation may increase pro-thrombotic activity, favoring microthrombosis, and affect small vessel autoregulation and capillary heterogeneity [ 4 ]. Early studies, assessing BBB permeability using dynamic contrast-enhanced MRI, showed that patients with lacunar strokes have increased BBB permeability, compared to patients with cortical strokes [ 64 ].
Other measures of vascular function as cerebrovascular reactivity appeared to be impaired in patients with SVD [ 65 ] and lacunar strokes [ 66 ] in a few cross-sectional studies. However, it is difficult to obtain these measures prior to the appearance of new subcortical infarcts in longitudinal studies, due to the relatively low rates of incident strokes and use of secondary prevention measures.
The radiological fate of RSSI is variable and hardly predictable, as one-third of RSSI evolve into a lacune, while others may disappear or leave a non-cavitated lesion [ 67 , 68 ]. BBB leakage into CSF appeared to be a predicting factor of cavitation in one longitudinal study [ 69 ], but further longitudinal studies might identify other risk factors. The clinical and prognostic relevance of RSSI cavitation remains to be determined, although some associations have been found with severe progression of SVD and cognitive impairment [ 70 ].
Nevertheless, most lacunes might not be related to prior clinical events and represent accidental findings on neuroimaging studies. The spatial correlation with motor and sensitive pathways is highly related to overt clinical symptoms [ 71 ], but some lacunes, even in eloquent areas, might not have been recognized clinically.
Therefore, some lacunes might result from progressive injury and cavitation, which could be less clinically evident. For example, new cavities usually appear silently in the edges of white matter hyperintensities in patients with CADASIL [ 72 ], and lacunes are associated with deep medullary vein stiffening and occlusion, due to venous collagenosis [ 73 ].
Patients with lacunar strokes present a pro-thrombotic state, demonstrated by overall increased plasma levels of tissue plasminogen activator TPA , plasminogen activator inhibitor PAI , fibrinogen, and D-dimer, compared to patients without stroke, but lower levels, compared to other stroke subtypes, characterized by larger infarct volumes [ 38 , 74 ].
Similarly, endothelial activation markers homocysteine and von Willebrand factor and leukocyte adhesion molecules E-selectin, P-selectin, ICAM-1, and VCAM-1 expression is augmented in patients with lacunar stroke, compared to healthy controls, but not different from other stroke subtypes [ 38 , 74 ]. Several plasma markers of inflammation have been assessed in patients with SVD and lacunar strokes [ 38 ].
C-reactive protein CRP is a sensitive, but not specific, marker of systemic inflammation that has been related to stroke risk in the community-dwelling population [ 75 ] and risk of ischemic recurrence in patients who had a lacunar stroke [ 76 , 77 ]. However, the levels of most inflammatory markers were similar, or even lower, in patients with lacunar stroke, compared to other stroke subtypes, suggesting that most of these markers are due to the impact of the acute ischemic injury and may depend more on the stroke volume, rather than the different etiology [ 39 ].
Table 2 summarizes the potential biomarkers of lacunar strokes that have been previously studied, grouped by their primary related pathophysiological mechanism. Higher in lacunar stroke vs. Direct evidence on SVD and small lacunar infarcts pathophysiology is particularly challenging to obtain from post-mortem studies and in neuroimaging for the low mortality and limited spatial definition, respectively.
Therefore, experimental models of lacunar strokes are warranted to broaden the knowledge on the pathophysiological mechanisms and identify new therapeutic targets. However, several technical and conceptual issues may limit their translatability to humans [ 6 , 7 ].
There are different techniques to obtain small subcortical ischemic lesions, modeling lacunar infarcts, that include lesions produced by different mechanisms not consistent with SVD pathophysiology i. While the induced focal ischemic techniques are more reproducible, the spontaneous ones are difficult to trace or know the exact beginning. The main advantages and flaws of each technique are summarized in Table 3. In the s, C. Fisher described the histopathological correlates of four clinical syndromes pure motor, pure sensitive, ataxic-hemiparesis, and clumsy-hand dysarthria , defined as lacunar syndromes [ , ].
Some years later, J. Mohr et al. Other atypical syndromes have been described, including monoparesis, partial cortical, or extrapyramidal symptoms, as well as deficits due to cranial nerve nuclei involvement in brainstem infarcts [ 8 , ]. The diagnostic accuracy of the lacunar syndromes for RSSI has been addressed in several studies, most of them using MRI as the gold standard for lesion location, as detailed in Table 4.
Modified from Potter et al. The confirmation of a RSSI in patients presenting with a lacunar syndrome requires identification on neuroimaging either CT or MRI of a lesion consistent with a small ischemic stroke in the territory of a single deep perforating artery lenticulostriate, thalamoperforating, thalamogeniculate, paramedian, and deep medullary arteries , corresponding to subcortical white matter centrum semiovale and corona radiate, internal and external capsule, and short and long fibers in the brainstem or deep grey structures basal ganglia, thalamus, and nuclei in the brainstem.
CT was the first technique capable of identifying small focal hypoattenuations consistent with lacunar strokes [ ]. Small subcortical infarcts are hardly visible as early small ischemic changes in the first hours after symptom onset on CT scans and difficult to distinguish from older lesions in patients with SVD.
In particular, the implementation of DWI was crucial to identify recent lesions as hyperintensities few minutes from stroke onset and remaining visible for about 3—5 weeks , while older lesions are visible in the other structural sequences [ , ]. Despite the high diagnostic accuracy of MRI, small lesions might be missed, depending on several factors, such as the magnetic field, correction of motion artifacts, and width of the consecutive slice acquisition [ ].
Thus, the absence of hyperintense lesions on DWI should not rule out a lacunar stroke in the presence of a lacunar syndrome. Finally, the presence of a RSSI on MRI could represent the residual infarction of a larger perfusion deficit involving more than a perforating artery or large vessel territories, as shown in some perfusion studies [ ].
In other cases, perfusion deficits in the territory of one perforating artery may be reversible [ 55 ]. A stroke results from dynamic ischemic processes, depending on several factors, such as metabolic demand, collateral blood supply, time of ischemia, and reperfusion. The snapshot provided by imaging studies might provide incomplete information that needs to be complemented by clinical assessment and appropriate complementary exams.
Even so, the etiological diagnosis must be considered presumptive in lacunar stroke in the absence of a pathological confirmation and, especially, cautious in case of incomplete or inconclusive workup or when possible concomitant causes are present [ ]. Identifying RSSI is particularly challenging in the acute stroke assessment for technical limitations of standard imaging techniques.
However, imaging may assist clinicians in the early presumptive diagnostic orientation for assessing reperfusion in eligible patients, secondary prevention strategies, and the clinical interpretation of threatening clinical courses, such as neurological deterioration and stuttering symptoms in lacunar strokes. The most commonly adopted techniques for acute stroke assessment are based on CT imaging, while MRI is used in fewer centers and might be less practical and more time-consuming in the emergency service.
Although the accuracy of non-contrast CT evaluation is extremely low in the acute phase, multimodal imaging, including CT angiography and perfusion maps, may improve the detection of small perfusion deficits corresponding to lacunar stroke. Several studies confirmed the utility of CT perfusion in lacunar stroke assessment in the past few years Table 5 , despite some important limitations, due to low sensitivity for very small infarcts and those located in the brainstem and lack of external validation and automatic detection tools.
In addition, sensitivity and specificity are not comparable between studies, due to different population, selection criteria, RSSI prevalence, and study design. For example, some of the studies had extremely high specificity, probably due to pre-evaluation selection of patients or strict criteria to identify a perfusion deficit [ , , , ].
Nevertheless, the accuracy of non-contrast CT is highly improved by perfusion maps [ 43 , , , ], which should be carefully evaluated for the presence of focal perfusion alterations, consistent with the clinical presentation. No disease-specific treatment targeting intrinsic SVD mechanisms currently exists.
Therefore, patients with lacunar stroke should receive the treatments that have demonstrated their efficacy in the acute stroke treatment and secondary prevention, such as systemic thrombolysis and antithrombotic therapies, respectively, to avoid irreversible damage in the brain. Some concerns have been raised about the efficacy of this therapy in lacunar strokes, since the underlying pathophysiology might be related to mechanisms alternative to thrombosis in small vessel disease.
However, the main RCTs that proved the efficacy of systemic thrombolysis in patients with stroke included patients with lacunar syndromes and showed no effect modification by the presumed vascular subtype [ ]. In terms of safety, the risk of haemorrhagic complications after systemic thrombolysis in patients with lacunar infarcts is lower than in patients with other stroke etiologies; additional observational studies supported the benefit of this treatment in all stroke subtypes [ , ].
Therefore, intravenous thrombolysis is indicated for patients presenting with a lacunar syndrome in the first 4. Recent studies demonstrated that systemic thrombolysis is also effective in the extended time window more than 4. Other studies extending the time for thrombolysis in emergency neurological deficits trial, ECASS IV-ExTEND , based on penumbra quantification using CT perfusion, demonstrated the efficacy of IV thrombolysis in stroke with large volume, thus excluding patients with small subcortical infarcts [ ].
Future studies should assess which perfusion maps are most accurate for selecting patients with small perfusion deficits for reperfusion in the extended time window, including those with mild symptoms and focal hypoperfusion, in the territory of a perforating artery that might be at risk of neurological deterioration [ ]. Any single antiplatelet therapy is effective for the secondary prevention of ischemic strokes of almost all subtypes, including lacunar ischemic strokes [ ].
Dual antiplatelet therapy DAPT has been assessed for secondary prevention of ischemic stroke, including lacunar strokes. The SPS3 trial showed that acetyl-salicylic acid ASA plus clopidogrel in patients with lacunar stroke in the prior six months did not reduce the incidence of new strokes but increased the risk of bleeding and death [ ].
However, later trials demonstrated the efficacy of short-term DAPT started early 12—24 h and maintained for 21—90 days, compared with single antiplatelet therapy in patients with mild strokes and TIA. The clopidogrel in high-risk patients with acute non-disabling cerebrovascular events CHANCE [ ] and platelet-oriented inhibition in new transient ischemic attack and minor ischemic stroke POINT [ ] trials assessed the efficacy of ASA plus clopidogrel vs.
ASA alone decreased the incidence of new strokes and cardiovascular events, despite minor increases in haemorrhagic risk, which was higher in studies with longer DAPT treatment. Nevertheless, few data are available in the subgroups of patients with lacunar strokes in these RCTs. A post hoc analysis of the CHANCE trial showed that patients with multiple strokes had lower stroke recurrences than those with a single stroke about half of them were classified as lacunar strokes , which benefited more from DAPT vs.
ASA alone [ ]. Some observational studies showed that DAPT is safe in patients with lacunar infarct and early neurological deterioration, even in those who received IV tPA, and seemed to improve the functional outcomes [ , , ]. Therefore, DAPT is not indicated in patients with a history of prior lacunar stroke. However, DAPT might be the best option for early secondary prevention in patients with mild lacunar stroke for a short period, as recommended by the American and European Guidelines [ , ].
Moreover, DAPT might limit the effect of antiplatelet resistance, measured by impedance aggregometry, to either ASA or clopidogrel in mild strokes, especially in patients with SVD [ , ]. Patients with a lacunar stroke presenting with high NIHSS might also benefit from DAPT, since they have a relatively small infarct volume, compared to cortical strokes with similar clinical severity and theoretically lower risk of haemorrhagic transformation.
Imaging selection, according to stroke volume and other SVD factors that increase the risk of intracranial bleeding i. Cilostazol is a phosphodiesterase-3 inhibitor commonly used in Asiatic countries for stroke prevention with mild antiplatelet effect and other properties on endothelial dysfunction, myelin repair, neuroprotection, and inflammation.
A recent meta-analysis of RCTs, comparing cilostazol vs. ASA, clopidogrel, or placebo, suggested that cilostazol is effective for stroke prevention, without increasing the hemorrhagic risk [ ]. The best management of secondary prevention antithrombotic drugs in patients with lacunar stroke is still debated, and further RCTs are needed. At the moment, strong antiplatelet prevention with DAPT, instead of single antiplatelet therapy, should be considered only for mild strokes for the first few weeks after acute stroke, when the ischemic recurrence risk is higher.
Future trials are warranted to confirm whether adding cilostazol to aspirin or clopidogrel for long-term prevention could offer additional protective effects, due to non-platelet activity, without increasing the hemorrhagic risk.
Despite the efficacy of antiplatelet therapy in preventing new strokes, lacunar infarcts represent only the tip of the iceberg of SVD. The progression of the disease and appearance of related serious conditions, such as cognitive impairment, extrapyramidal syndromes, and psychiatric disorders, might require other treatments targeting alternative mechanisms in SVD.
A post hoc analysis, according to stroke subtypes, showed that patients with large and small vessel occlusions benefited similarly from statin use [ ], reassuring some of the concerns rose about the possible increased haemorrhagic risk in patients with SVD. However, there is no consensus about the target for LDL reduction in these patients. The hypertension-induced mechanisms in SVD are complex and include structural and functional maladaptation to high blood pressure and arterial pulsatility, oxidative stress, endothelial dysfunction, BBB disruption, capillary rarefaction, and impaired neurovascular coupling [ ].
The effect of hypertension might not be the same in deep perforating and cortical perforating arteries. The former are more exposed to hypertensive injury, due to the high pressure gradient from the main proximal cerebral arteries, while the latter deep medullary arteries penetrating the supratentorial white matter depends on the distal leptomeningeal circulation, with a low pressure gradient, and might be more prone to hypoperfusion [ ].
Avoiding hypertension is indicated in the secondary prevention of patients having a stroke [ , ]. However, the optimal blood pressure target in patients with lacunar stroke is unknown. Notably, the incidence of stroke recurrences in SPS3 was low in both arms, suggesting that a comprehensive management of patients with lacunar infarcts is advantageous, leaving small room for further benefit attributable to intensive blood pressure lowering.
On the other hand, inducing hypotension in patients with SVD could affect the compensatory mechanism in the presence of altered arteriolar stiffness and autoregulation. The potentially harmful effect of intensive blood lowering could also be more relevant in the hyperacute phase for the potential decrease in residual compensatory perfusion flow that could accelerate the ischemic process.
Lifestyle interventions include a range of behaviorally modifiable risk factors, such as smoking, physical activity, and diet i. However, few studies were conducted in the specific population of patients with a lacunar stroke. Nevertheless, the clear evidence from prior studies, including all subtypes of strokes, encouraging physical activity after stroke can be extrapolated for the lacunar subtype.
The current management for patients presenting with a lacunar stroke is based on reperfusion treatment with thrombolytic agents and secondary antithrombotic prevention antiplatelets , as well as other interventions on modifiable vascular risk factors i.
However, no specific treatment for SVD exists, and new possible therapeutic targets, involving different mechanisms in SVD, are currently under investigation Table 1. As aforementioned, cilostazol is a promising drug in SVD for non-antiplatelet activity on BBB integrity, vasodilation, inflammation, and neuroprotection. A small RCT trial, conducted in Korea effect of cilostazol in acute lacunar infarction, based on pulsatility index of transcranial doppler, ECLIPse , showed that adding cilostazol to aspirin in the secondary prevention of patients with lacunar stroke decreased intracranial pulsatility in the main cerebral arteries, confirming the pleiotropic effect of cilostazol beyond the antiplatelet activity [ ].
The LACI-1 was a phase IIa trial that indicated the safety and tolerability of cilostazol and isosorbide mononitrate an oxid nitric donor commonly used in angina in patients with a lacunar stroke, also showing an improvement of vascular function in the white matter measured using cerebrovascular reactivity in blood oxygenation level dependent BOLD -MRI.
Inflammation represents a potential target in stroke secondary prevention that could particularly fit with SVD etiology, since mechanisms other than thrombosis seem to have a pivotal role outside the acute stroke phase. The URICO-ICTUS trial showed promising results on the efficacy of a potent endogenous antioxidant molecule, such as uric acid, associated with systemic thrombolysis in acute ischemic stroke patients [ 41 ].
Although uric acid was not significantly superior to the placebo in the primary outcome measure excellent outcome defined as modified Rankin Score 0—1 at day follow-up, adjusted risk ratio 1. However, the efficacy in the stroke population has not been assessed yet [ 42 ].
Systemic thrombolysis in patients with lacunar stroke attending later than 4. It often occurs in patients with stuttering and progressively worsening symptoms. However, the thrombolysis indication in this subgroup of patients is still uncertain, despite the encouraging results from the WAKE-UP trial [ ].
Perfusion studies in the acute stage could also identify patients with mild non-disabling symptoms but an evident, relatively large perfusion deficit in the territory of the perforating artery, which may present neurological deterioration and possibly benefit from thrombolysis. While MRI is not feasible in the acute stroke assessment in most stroke centers, automatic CT perfusion software packages are not helpful for detecting small perfusion deficits, and visual assessment could be challenging, especially for untrained readers.
Therefore, multicentric studies, pooling large series of patients with lacunar strokes, are warranted to improve the automatic detection of small perfusion alterations and validate the results obtained in smaller, single-center cohorts. Secondary prevention measures, mainly based on antiplatelet and vascular risk factors control, are not much different from other non-cardioembolic ischemic strokes.
However, long-term DAPT is hazardous in patients with SVD for increasing the bleeding risk, while the risk of late stroke recurrences and SVD progression is higher in patients with lacunar strokes than in those with large vessel stroke. For these reasons, the research of new drugs targeting non-thrombotic mechanisms of SVD is particularly encouraging for the long-term, secondary prevention of lacunar stroke.
This review is to be considered a broad overview on several pathophysiological, clinical, diagnostic, and therapeutic issues concerning lacunar stoke. Therefore, the main limitation of the review is the lack of a systematic literature search methodology. However, the main aim of the review is to provide a personal view for clinicians and highlight opportunities for future lines of research, including systematic reviews and meta-analyses on specific topics, such as biomarkers clinical relevance and secondary prevention approaches.
Lacunar ischemic strokes are not only a prevalent type of stroke but could also be the first clinical manifestation of SVD, which causes severe physical and cognitive impairment in the long-term. However, not all small subcortical lesions are due to SVD, and improvement in the diagnostic work-up, including advanced imaging, is desirable to exclude other concomitant causes.
Translational research is often necessary to develop of new treatments, but optimal animal models of lacunar strokes, mimicking the same underlying mechanisms, are lacking at the moment. On the clinical side, surrogate markers of vascular functions in SVD in neuroimaging are not fully developed and validated.
More efforts are needed in the future to encourage the external validation of new SVD markers and include them in large multicenter prospective studies, including RCTs. Using homogenous definitions of SVD markers, standards in the acquisition and processing of SVD imaging are crucial for interpretating and comparing different studies. Conceptualization, S. All authors have read and agreed to the published version of the manuscript.
Int J Mol Sci. Published online Jan Find articles by Salvatore Rudilosso. Find articles by Xabier Urra. Paola Rocca, Academic Editor. Author information Article notes Copyright and License information Disclaimer.
Received Dec 21; Accepted Jan Abstract Lacunar infarcts represent one of the most frequent subtypes of ischemic strokes and may represent the first recognizable manifestation of a progressive disease of the small perforating arteries, capillaries, and venules of the brain, defined as cerebral small vessel disease. Keywords: cerebrovascular disease, stroke, ischemic stroke, lacunar stroke, small vessel disease, recent small subcortical infarcts. Terminology and Correlations between Histopathological, Clinical and Imaging Definitions The terminology adopted to describe small cerebral infarcts, in the territory of perforating arteries, counts tens of different terms that have been used in research and clinical practice [ 5 ].
Open in a separate window. Figure 1. Figure 2. Histological—clinical—radiological correlations in lacunar strokes. Figure 3. Mechanisms of Lacunar Strokes: From Pathology Studies to Advanced Neuroimaging Lacunar ischemic strokes are highly associated with hypertensive arteriosclerosis and other vascular risk factors [ 16 , 17 , 18 ]. Table 1 Possible mechanisms involved in lacunar stroke pathogenesis. Superposed microthrombosis may lead to complete arteriolar occlusion. Typical histopathological findings in perforating arteries.
Indirect evidence from high field MRI techniques [ 19 , 20 ]. Non hypertensive patients may also present with lacunar stroke [ 21 ]. In vivo radiological confirmation of small artery wall alterations are not available. Hypertension is the most modifiable risk factor for stroke secondary prevention [ 22 ]. In patients with lacunar strokes, intensive vs. Atherosclerosis branch atheromatous disease Atherosclerotic plaques in the main cerebral vessel may occlude the orifice of perforating arterioles [ 24 , 25 ].
Anatomopathological studies [ 18 ]. Small plaques are also visible using high field MRI techniques for vessel wall assessment [ 24 ]. Atherosclerosis in large vessel arteries may represent an epiphenomenon. Other new drugs aimed to stabilize the inflammatory process in atherosclerosis, which might represent a promising therapeutic target. Microembolisms Small emboli, either from proximal atherosclerotic plaques or cardiac source, may produce single or multiple small subcortical infarcts.
Perforating arteries in lacunar strokes may be patent in pathology studies [ 8 ] and advanced 7T MRI techniques [ 27 ]. Increased blood flow on CT perfusion suggests recanalization of an embolic occlusion of a perforating artery [ 28 ]. Subcortical infarcts in animal models produced by microembolism [ 6 ]. There is an association between atrial fibrillation, load of subcortical infarcts, and WMH [ 29 ], but direct evidence of embolism is lacking.
Treatments aimed to stabilize active plaques or anticoagulant treatment, in case of mayor embolic source. Prothrombotic state i. Chronic global cerebral hypoperfusion Chronic hypoperfusion of distal vascular territories may lead to progressive ischemia in the white matter. In animal models, small subcortical infarcts may be produced by bilateral carotid occlusions [ 6 ].
The causal relationship between hypoperfusion and SVD progression in longitudinal studies is controversial [ 31 ], as hypoperfusion might also be also secondary to reduced metabolism in WMH. Vasodilatory drugs to increase brain perfusion: mononitrate isosorbide, nitric oxide. LACI-2 [ 32 ]. Inflammation, endothelial dysfunction, and BBB disruption Endothelial dysfunction may trigger the pro-inflammatory mechanisms promoting pro-thrombotic agents, microglial activation, altered neurovascular homeostasis, and impaired coupling between metabolic demand and nutrient supply.
Markers of BBB leakage in pathology studies [ 33 , 34 ]. Association between the number of lacunes and inflammatory blood markers [ 35 ]. BBB permeability on dynamic contrast enhanced MRI is increased in lacunar strokes, compared to cortical strokes [ 36 ]. Some studies on post-mortem brain samples did not confirm the association of markers of endothelial dysfunction or BBB leakage and SVD [ 37 , 38 ]. A causal relationship with focal BBB leakage prior lacunar strokes is to be determined.
Blood markers of endothelial dysfunction and inflammation are are not specific of lacunar stroke subtype [ 39 ]. Focal hypoperfusion and compensatory blood flow in acute perforating artery occlusion Abrupt reduction in blood flow after perforating artery occlusion, regardless the causing mechanisms either intrinsic SVD or atheroembolic. The extent and the time to establish infarction may depend on factors such as compensatory blood flow through capillary network and cerebrovascular reserve.
Perfusion studies show persistence of residual blood flow, in the territory of perforating arteries corresponding to RSSI [ 43 , 44 ]. Sequential imaging from row perfusion sequences may show retrograde flow, suggesting collateral circulation involvement in RSSI [ 28 , 45 , 46 ] Microscopic studies showed a dense capillary network, linking contiguous perforating arteries and few arteriolar anastomoses [ 47 ].
Lack of direct evidence of perforating artery occlusion and recruiting collateral circulation in RSSI Thrombolysis in lacunar stroke would not be effective without compensatory mechanisms maintaining the tissue viable until recanalization. Perfusion imaging-based thrombolysis, outside of the conventional time window, may also be effective in patients with RSSI. Vasodilatory agents may improve collateral recruitment.
Neuroprotective agents may reach the ischemic area through retrograde in the territory supplied by an occluded perforating artery. Table 2 Plasma biomarkers in lacunar stroke. Insights from Translational Research Direct evidence on SVD and small lacunar infarcts pathophysiology is particularly challenging to obtain from post-mortem studies and in neuroimaging for the low mortality and limited spatial definition, respectively.
Table 3 Experimental models of stroke modeling lacunar infarcts. Table 4 Lacunar syndrome: correspondence with imaging findings. Neuroimaging in Patients with Suspected Lacunar Stroke The confirmation of a RSSI in patients presenting with a lacunar syndrome requires identification on neuroimaging either CT or MRI of a lesion consistent with a small ischemic stroke in the territory of a single deep perforating artery lenticulostriate, thalamoperforating, thalamogeniculate, paramedian, and deep medullary arteries , corresponding to subcortical white matter centrum semiovale and corona radiate, internal and external capsule, and short and long fibers in the brainstem or deep grey structures basal ganglia, thalamus, and nuclei in the brainstem.
Reference Population Perfusion Maps Main Findings Rudilosso, [ 43 ] A total of 33 patients with lacunar syndrome 16 lacunar strokes, 13 non-lacunar strokes, and 4 no ischemic lesions. TTD was the most informative map for the identification of ischemic lesions. Das, [ ] A total of 88 patients with lacunar syndrome after excluding stroke mimics.
CTP increased the diagnostic performance 5-fold over non-contrast CT. Tan, [ ] A total of patients with ischemic strokes 31 single subcortical, 9 multiple subcortical, 34 cortical only, 33 non-confluent cortical-subcortical, and 75 confluent cortical-subcortical.
No false positive perfusion images were rated. Patients without lesions on DWI were excluded. Intravenous Thrombolysis Some concerns have been raised about the efficacy of this therapy in lacunar strokes, since the underlying pathophysiology might be related to mechanisms alternative to thrombosis in small vessel disease.
Secondary Prevention Antplatelets Any single antiplatelet therapy is effective for the secondary prevention of ischemic strokes of almost all subtypes, including lacunar ischemic strokes [ ]. Anti-Hypertensive Treatments The hypertension-induced mechanisms in SVD are complex and include structural and functional maladaptation to high blood pressure and arterial pulsatility, oxidative stress, endothelial dysfunction, BBB disruption, capillary rarefaction, and impaired neurovascular coupling [ ].
Lifestyle Interventions Lifestyle interventions include a range of behaviorally modifiable risk factors, such as smoking, physical activity, and diet i. New Molecular Targets in Lacunar Stroke The current management for patients presenting with a lacunar stroke is based on reperfusion treatment with thrombolytic agents and secondary antithrombotic prevention antiplatelets , as well as other interventions on modifiable vascular risk factors i.
Future Directions Systemic thrombolysis in patients with lacunar stroke attending later than 4. Limitations of the Review This review is to be considered a broad overview on several pathophysiological, clinical, diagnostic, and therapeutic issues concerning lacunar stoke.
Conclusions Lacunar ischemic strokes are not only a prevalent type of stroke but could also be the first clinical manifestation of SVD, which causes severe physical and cognitive impairment in the long-term. Author Contributions Conceptualization, S. Institutional Review Board Statement Not applicable.
Informed Consent Statement Not applicable. Conflicts of Interest The authors declare no conflict of interest. References 1. Arboix A. Norrving B. Long-Term Prognosis after Lacunar Infarction. Lancet Neurol. Blanco-Rojas L. BMC Neurol. Wardlaw J. Bailey E. Mustapha M. Fisher C. Lacunar Strokes and Infarcts: A Review. Poirier J. Cerebral Lacunae. A Proposed New Classification. Lammie G. Brain Pathol. Adams H. Definitions for Use in a Multicenter Clinical Trial.
Trial of Org in Acute Stroke Treatment. Amarenco P. Humphreys C. Regenhardt R. JAMA Neurol. Caplan L. Xie W. Ling C. Stroke Cerebrovasc. Zonneveld T. Cochrane Database Syst. Sps T. Petrone L. Suzuki T. Rudilosso S. Blood Flow Metab. Lee J. Stewart C. Stroke J. Roseborough A. Simpson J. Low A. Recover the refrigerant and check there is no refrigerant in the equipment. When the pressure has lowered until indication of the compound gauge pointed Connect the charge hose to the packed valve service ports at gas side, liquid side, and balance side of the outdoor unit.
Leave it as it is for 1 to 2 minutes and check the indicator of the compound gauge does not return. Connect the charge hose to vacuum pump adaptor. Open the packed valves of the balance pipe fully at liquid and gas sides, and then return the valve at gas side a little to the closed side. Open fully PMV of the outdoor unit. Open fully the handle Low of the gauge manifold, and then turn on the power of vacuum pump for vacuuming. Set the refrigerant cylinder on the electron balance, connect the charging hose to connecting ports of the cylinder and the electron gauge, and then charge the liquid refrigerant from the service port at liquid side.
Shield with the gauge manifold so that refrigerant does not flow to gas side. When the specified amount of refrigerant cannot be charged, charge the liquid refrigerant into the service port at suction gas side while carrying out the all cooling operation. In this time, reduce slightly amount of refrigerant with valve of the cylinder for charging. The liquid refrigerant may be rapidly charged, so charge the refrigerant carefully and slowly.
Q R Never charge the refrigerant over the specified amount. Do not charge the additional refrigerant. Q R Set the equipment so that liquid refrigerant can be charged. When using a cylinder with siphon pipe, liquid can be charged without inversing the cylinder. Therefore if the refrigerant gas is charged, the composition of the charged refrigerant changes and characteristics of the equipment changes.
If the air remains, the pressure in the refrigerating cycle becomes abnormally high and an injury and others are caused due to burst. As it is available to operate simultaneously in cooling and heating modes, more amount of heat recovery becomes possible.
This system is the most appropriate one for a building or etc. Heating and cooling operation are automatically selected in individual unit; You can save time for operation. For example, when heating is required for early morning and cooling for daytime, a Flow Selector Unit provides automatically a smooth selection of heating or cooling operation.
For this reason, the following table explains the operation modes of this air conditioner. The following table explains representation of the operation modes in this Manual. All Cooling All indoor units are under cooling operation only without heating operation. Outdoor heat exchanger Main heat exchanger is used as condenser. All Heating All indoor units are under heating operation only without cooling operation. Outdoor heat exchanger Main heat exchanger is used as evaporator.
Simultaneous operation MIU for simultaneous operation Defrost Using reversing operation of 4-way valve, ice of the outdoor heat exchanger is dissolved with single cooling cycle. Capacity code is not actual capacity If total capacity code value of indoor unit exceeds that of outdoor unit, apply capacity code of outdoor unit. When using Y-shape branching joint for 1st branching, select according to capacity code of outdoor unit.
Model names for outdoor described in this guide are shortened because of the space constraint. TEST No. U1 U2 2. A dotted line and broken line indicate the wiring at site. Letter at inside indicates the terminal number. A dotted line and broken line indicate the wiring at side.
When attaching a drain pump, exchange CN connector with a connector of the float switch. A part is connected to the terminal block. When exchanging to the outside static pressure necessary at the local site, check the terminal No. Pay attention to change static pressure because the outside static pressure of H tap in 50 or 60Hz. Tel: Adpter for wireless remote controller 3. Wired remote controller 1 1 2 2 Color identification X Y 1.
Remote Controller Indicates the terminal bolock. Indicates the terminal bolock. Indicates the terminal bolock, letter. Pipe temp. IPDU No. The two-dot chain line indicates wiring at the local site, and the dashed line indicates accessories sold separately and service wires, respectively. Otherwise water enters into the box resulting in a trouble.
Name of Each Part Outdoor Unit Air outlet Discharge Hot air is discharged when cooling operation is performed. Cold air is diacharged when heating operation is performed. It is included in the electric parts box. Air inlet They are provided at front, rear, left, and right sides. Power source hole Refrigerant pipe connecting hole Fixing leg Connecting valve is included inside here. Air in the room is sucked from here Air in the room is sucked from here.
For details, consult with the dealer which you have purchased the air conditioner. Air filter Air filter Removes dust and trash. Air filter is provided in the air inlet grille. Remo ves dust and trash. Air filter is pro vided in the air inlet grille. Earth screw Suction duct is connected. Air outlet Discharge duct is connected. Air filter Removes dust and trash. Air filter is provided in the air grille.
Air inlet grille Air in the room is sucked from here. Air in the room is sucked from here No. Earth screw It is included in the electric parts box. Earth screw Drain pan Earth screws are provided in the electric parts box. CODE No. Center panel Air inlet Air in the room is sucked from here.
Air filter is provided in the center panel. Air inlet port The air in the room is sucked in from this port. Earth screw Earth screws are provided in the electric parts box. Air filter Removes dirt or dust. It is included in the suction port.
Air inlet port Sucks air inside of the room from here. Air outlet port Drain pan With drain filter This accessory is installed at the local site. Front panel Lower side 4 Air filter Removes dirt or dust. Time of the timer is displayed. When a trouble occurs, the check code is displayed.
Displayed while the sensor of the remote controller is used. Displayed during a test run. TEST run display Displays flap position. While this indication is displayed, the indoor fan stops or the mode enters in LOW. Displayed during setup of the timer. In reality only, the selected contents are indicated.
While this display is flashing, the model is being automatically confirmed. Air filter Removes dust or trash. Provided on the suction port. Display section Earth screw It is prepared in the electric parts box. The contents available to be set up on the remote controller differ according to the central control mode. Fax: Heronhill - for all your Toshiba requirements Operation section Correct Usage Push each button to select a desired operation.
From the next time, the operation displayed on the remote controller will start by pushing the button only. Fan button FAN button is used when a fan which is sold on the market or etc. When the operation has stopped, the operation lamp and all the displays disappear. Set up temperature button Adjusts the room temperature. Set the desired set temperature by pushing or. Swing automatically or manually Operation lamp Lamp is lit during the operation. Lamp is off when stopped. Although it flashes when operating the protection device or abnormal time.
During normal operation, do not use this button. The temperature on the surrounding of the remote controller can also be sensed. For details, contact the dealer from which you have purchased the air conditioner. The operation lamp goes on, and the operation starts. LOW One push of the button, and the display changes in the order shown on the right. Therefore it slightly differs from the room temperature according to the installation status.
The setup value is a criterion of the room temperature. Automatic air speed cannot be selected in FAN mode. Stop Push button. The operation lamp goes off, and the operation stops. Automatic Operation Auto Changeover TIMER Operation When you set the air conditioner in mode or switch over from AUTO operation because of some settings change, it will automatically select either cooling, heating, or fan only operation depending on the indoor temperature.
A type of timer operation can be selected from the following three types. OFF timer : The operation stops when the time of timer has reached the set time. Repeat OFF timer : Every time, the operation stops after the set time has passed. ON timer : The operation starts when the time of timer has reached the set time.
Temperature button Set the desired temperature. For every push of button, the set time increases in the unit of 0. The maximum set time is For every push of button, the set time decreases in the unit of 0. The minimum set time is 0. Push SET button. When ON timer is activated, time is displayed, and after time of the timer has been up, displays other than ON disappear. Push this button again to stop the air conditioner. Re-Installation Information Confirmation before operation DANGER Ask the dealer or an installation professional to re-install the air conditioner to a new place or move it to another place and to observe the following items.
If the air conditioner is inappropriately by installed by yourself, it may cause electric shock or fire. If the unit is installed in such place, noise transmitted from the air conditioner affects the operation of these appliances.
If the outside temperature falls, the heating capacity decreases. If the protective device works, turn off the main power switch, solve the cause, and then start the operation again. The indoor unit in heating mode continues operation. When the operation mode has been fixed to cooling or heating by the system manager of the air conditioner, an operation other than the setup mode cannot be performed.
Tel: Protective device High pressure switch This device stops automatically an operation when excessive force is applied on the air conditioner. If the protective device works, the operation stops and the operation lamp flashes. When the protective device works, the indication and the check code are displayed on the display section of the remote controller.
In the following cases, the protective device may work. Fax: Heronhill - for all your Toshiba requirements As the characteristics of air, cool air collects at lower levels, and hot air collects at higher levels. If cooling operation is performed with the flap blowing air downwards, the air outlet or surface of the flap will be wet with dew, and dewdrop may fall down.
Use the flap operation switch on the remote controller to change direction of the horizontal flap. The horizontal flap does not stop even if pushing the horizontal flap. Adjusting the stop position, push the switch. Use the air outlet flap with downward set point.
How to set up the air direction 1 Push during operation. The air direction changes for every push of the button. If directing at upward, hot air may not come to the foot. If directing it downward, the dew may from on the surface of the air discharge port and may drop down. After then, if pushing , the air direction descends from the highest position. If stopping the flap as it directs downward during swing operation, it stops after moving to the 3rd position from the highest position.
No display Then the indoor unit No. For the displayed indoor unit, set up the air direction. When a remote controller operates the multiple indoor units, an indoor unit is selected and air direction can be individually set up. Push again during swinging of the flap. Unit No. Then the indoor unit No.
In heating operation In cooling operation In heating operation, use the air outlet flap with downward set point so that the hot air is spread to the floor. In cooling operation, use the air outlet flap with horizontal set point so that cool air diffuses the whole room. In heating operation In heating operation, use the air outlet flap with downward set point so that the hot air is spread to the floor. In cooling operation In heating operation For Heat-pump model only In cooling operation, use the air outlet flap with horizontal set point so that the cold air diffuses in whole room.
In heating operation, use the air outlet flap with downward set point so that the hot air blows at the foot. In cooling operation, move the flap with hands and use it with horizontal air outlet point so that the cold air diffuses in whole room.
In heating operation For Heat-pump model only In heating operation, move the flap with hands and use the air outlet flap with downward set point so that the hot air blows at the foot. In heating operation, use the air outlet flap with downward set point so that the hot air is spread at the foot.
Lift up the vertical flap lightly, direct it toward the desired direction, and lower it. In this case, do not use the Swing function. Air Conditioner Operations and Performance Maintenance 3 minutes protection function For maintenance, be sure to turn off the main power switch.
Power failure Power failure during operation will stop the unit completely. Turn off the main power switch or circuit breaker and then turn them on again. WARNING Warm air control In heating operation When the room temperature reaches the set temperature, the fan speed is automatically reduced to prevent to blow cold draft.
At this time, the outdoor unit will stop. Do not handle the buttons with wet hands; otherwise an electric shock may be caused. Otherwise, you may contact with revolving fan or active electrity when you insert your hands into the unit during running of the air conditioners.
Heating characteristics Preheating operation The air conditioner will not deliver warm air immediately after it is turned on. Warm air will start to flow out after approximately 5 minutes when the indoor heat exchanger warmed up. If is displayed on the remote controller, maintain the air filter. Heating capacity 39 In the heating operation, the heat is absorbed from the outside and brought into the room. This way of heating is called heat pump system. When the outside temperature is too low, it is recommended to use another heating apparatus in combination with the air conditioner.
If snow or freeze on the outdoor unit is left as it is, it may cause machine failure or poor warming. If water freezes in the drain hose or inside the outdoor unit, it may cause machine failure or poor warming. If the air conditioner operates in excess of this figure, the surface of the air conditioner may cause dewing. If air conditioner is used outside of the above conditions, safety protection may work.
Outdoor temp. Take out the air filter. Push Air filter Button 5 3 Mount the air filter. Suction grille Close the suction port. Push Strap to prevent falling 1 Button. Adjust cleaning interval according to conditions of adhered oil soot or dirt. Turn the lever at the bottom side of the main unit to take out the air filter. The air outlet flap can be removed to clean if necessary. Clamp Clean the air outlet flap with water.
Stepped screw 2 Mount the air outlet flap. Pull out filter downward while holding the frames. For cleaning method, please contact the dealer. Please ask the constructor or the dealer which you purchased the air conditioner. If the drain pan or drain port is clogged with dust, water is disabled to drain.
In some cases, water overflows from the drain pan and it may wet wall or floor. Be sure to clean the drain pan before the cooling season. The center panel can move either leftward or rightward. Remove it after confirmation. Take out the air filter by lifting up it once and then pull it downward. Remove the air filter by pulling it toward you. Inlet grille knob Inlet grille Air filter Inlet grille fixing knob Inlet grille Suck dust by a vacuum cleaner or clean with water. Slide Mount the air filter.
Close the inlet grille. For the remote controller, use a dry cloth. I will wipe soft and dry cloth! Air inlet glille Air filter Removes dirt or dust. It is included in the inlet grille. Suck dust by a vacuum cleaner or clean with water. If the air filter is clogged with dust, the performance of the air conditioner will deteriorate.
These may cause a crack or deformation. Thinner Polishing Benzene powder Chemical floor-cloth Do not use. Use after drying when it has not been used for a long time! Front panel Lower side Air filter Removes dirt or dust. If the drain pan or the drain receiver is clogged with dust, water may overflow causing getting wet on the floor.
Therefore conceal other parts than the air outlet and the air filter. Be sure not to touch the electric parts box, the surrounding lead wires, the refrigerant pipes, etc. How to Use the Air Conditioner Efficiently Close windows and doors often! They are flowing sound of refrigerant or draining sound of dehumidifier. It is not a failure. Exposing yourself for a long time in blowing air exerts a bad influence upon your health. Check again. Does not operate. Is it a power failure?
Is the power switch turned off? Is the power fuse or breaker blown? Has the protective device operated? The operation lamp goes on. Do not the outdoor temperature go out of the specified range? Are any door or window open? Is the air filter clogged with dust? Is discharge louver of the indoor unit set at appropriate position?
When the following symptoms are found, stop the operation immediately, turn off the power switch, and contact the dealer which you have purchased the air conditioner. Low pressure sensor Connector CN White 1 Detects low pressure and uses it to control capacity of compressor during all cooling operation and simultaneous operation 2 Detects low pressure and uses it to controls super heat during all heating operation and simultaneous operation Heater Compressor case heater Compressor 1 Connector CN White, Compressor 2 Connector CN Blue 1 Prevents liquid accumulation to compressor Accumulator case heater Connector CN Red 1 Prevents liquid accumulation to accumulator Balance pipe 1 Oil balancing in each outdoor unit This unit does not use this Balance pipe.
All Indoor Unit s Operating for Cooling Only cooling operation without heating operation Outdoor heat exchanger Main heat exchanger is used as condenser. All Indoor Unit s Operating for Heating Only heating operation without cooling operation Outdoor heat exchanger Main heat exchanger is used as evaporator. Heating thermo-OFF 5.
Heating thermo-ON 6. Note 2 May be controlled. Indoor Unit Control Specifications No. Item Outline of specifications 1 Power supply is reset. Heating operation is automatically selected with difference between setup temperature and room temperature.
Setup data Setup temp. B 16 7 Remarks A 1 In all cooling operation, the air conditioner operates as described below based upon temp. To prevent the heat exchanger from freezing, the operation stops. It is reset when the following conditions are satisfied.
Item Outline of specifications Remarks 8 Recovery control for cooling refrigerant and oil 1 The indoor unit which stops operation, thermostat is OFF, or operates in FAN mode opens PMV of the indoor unit by the specified opening degree when cooling refrigerant or oil recovery signal is received from the outdoor unit.
The protective control has priority. If the float switch continues operating for approx. In this time, if the specified time has passed, the measured time is reset and LCD display disappears. Outdoor Unit In this case, the status is same as one in usual thermostat-OFF, so the operation restarts. C started, this control is not performed during the specified time after defrost operation and defrost control.
When TE temp. Over the operation temp. Item Operation explanation and applied data, etc. Remarks 3 Capacity control 1 According to the capacity demand command from the indoor controller, the inverter frequency control of the outdoor units is determined.
If it is insufficient, the control shifts to the oil equation control. For the schematic diagram of oil short protective control. After then, if the protection stop is repeated 3 times, an error is determined. Restart is not performed.
This control is managed by the header outdoor unit. It is also used to recover oil in the outdoor heat exchanger in heating overload operation except with defrost condition. The indoor unit in cooling operation continues the operation. This control is individually executed by the header outdoor unit. This control is executed as necessary except during stop time and thermostat-OFF time. This control functions during defrost operation, heating start pattern controlling, all cooling operation, or mainly cooling, partly heating operation.
It is decreased by 1 step every 10 seconds until Pd pressure becomes below 3. Item 10 Compressor stop by high pressure release control This control is to forcedly stop the compressor in outdoor unit according to Pd pressure. This control is to prevent accumulation of refrigerant in the compressor case by turning of the power of heater while the compressor stops, and it is executed in all the outdoor units.
If electricity is not turned on for a specified time before the test run after installation, a trouble of the compressor may be caused. When the power has been interrupted for a long time and the operation starts from the status as it was, it is desirable to turn on the power before start of operation as per the test run time.
This control is used often together with the compressor winding heating control. In this case, the power sound may be heard but it is not a trouble. After reactivated, the error count is cleared if the operation continues for 10 minutes or more. Cooling operation in low ambient temperature 1 When low pressure is lowered, the freeze prevention control by the indoor unit TC sensor may decrease the frequency.
If this sound is not heard, PMV operation error is considered. However, this sound may not be heard at a place where outside sound takes precidence. It may cause error in opening. The valve is closed, and the valve is damaged by sealed liquid compression. Then, turn off the power once, and turn on the power again. The firstly displayed unit No. In this time, the fan of the selected indoor unit is turned on.
Every pushing UNIT button, the indoor unit numbers in the group control are successively displayed. In this time, the fan of the selected indoor unit only is turned on. Specify the item code DN using the setup temperature Select the setup data using the timer time and and buttons. OK if display goes on. How to Set Up the Cooling Only Indoor Unit When setting the specific indoor unit to Cooling Only unit without connecting to the flow selector unit, setup to the indoor unit to become the Cooling Only unit is necessary.
Perform setup in the following procedure. Setup to the indoor unit is performed by handling the wired remote controller. Even if a wired remote controller is not used, attach a wired remote controller for setup. For handling the wireless remote controller, refer to the manual attached to the wireless remote controller. Change the setup during stop of the operation. Be sure to stop operation of the air conditioner. Check that the displayed item code is .
In a group control, the firstly displayed indoor unit No. Select an indoor unit of which setup is to be changed. In this time, the position of the indoor unit of which setup is to be changed can be confirmed because the fan and flap of the selected indoor unit work. In this time, if the display changes from flashing to lighting, the setup completes. Cooling Only and Heat pump cannot exist in the same group. When the setup finished, push 6 button. The setup is determined. Pushing button has been pushed, the operation of the For some time after remote controller cannot be accepted.
ACV 0. The unit No. In this time, the fan of the selected indoor unit turns on. Every pushing UNIT button, the indoor unit numbers in group control are displayed successively. In this time, the fan of the selected indoor unit only turns on. Using the setup temp or Using the timer time or The setup data are as follows: Setup data button, specify the item code button, select the setup data. Pushing 2 returns the status to the usual stop status.
It is connected with cable to the control P. Status that card is inserted in the card switch box 2 Outside contact OFF : If the indoor unit is operating, it is stopped forcedly. Push button. The status returns to the usual stop status. Indoor control P. Applied Control in Outdoor Unit The following functions become available by setting the switches on the outdoor interface P.
Function No. If installing a discharge duct Below 35Pa 3. Discharge air volume in each outdoor unit is described in the following table. Set up the switches or the outdoor unit U1. Function Switch No. Bit Connector No. Used control P. CN BLU The upper limit capacity of the outdoor unit is restricted based on the demand request signal from outside. However do not turn on SW1 and SW2 simultaneously. ON Bit 2. Snowfall Fan Control Header outdoor unit interface P.
Usual operation Releases control. The control contents are accepted during leading and trailing of the input signal. The status of leading and trailing should be held for mm. OFF The control contents are accepted during trailing of the input signal. The status of trailing should be held for mm. SMH: Input signal for stop. Night Operation Control Header outdoor unit interface P. Capacity criterion during night operation control Capacity during control indicates values as described in the following table.
Procured locally 77 Tel: www. In case that a central control system is connected Before address setup Procedure and Summary of Test Operation A test operation is executed in the following procedure. Central control units Check the basic items, mainly the installation work.
Be sure to enter the check results in the check list 1 and 2. Check before test operation Check the main power supply is turned on. U1 U2 U3 U4 It is the check after the power has been turned on. Check the refrigerant circuit system is normally turned on. Set up the addresses. Check Items before Test Operation U1 U2 Prior to the test operation, check the following items so that there is no trouble in the installation work.
Check again cautious points on wiring. In case that a center control system is not connected: U1 U2 Indoor unit No. Set up at shipment from the factory Before address setup, remove the relay connector. Set up at shipment from the factory After address setup, turn off SW of the header unit except the smallest unit after check of trial operation.
Is the end terminal of the shield wire grounded? For details, refer to the installation manuals for outdoor unit, indoor unit, remote controller, or optional devices. Is capacity of the leak breaker appropriate? Is power of indoor units supplied collectively? Is the branch kit correct? Is drain water of the indoor unit arranged so that it flows without accumulation? Is thermal insulation of pipes good? Are valves of all the outdoor units fully opened?
For details, refer to the Installation Manual of Flow selector unit. Check at Main Power-ON Address Setup After turning on the main power of the indoor units and outdoor unit in the refrigerant line to be executed with a test operation, check the following items in outdoor and each indoor unit.
After power-ON, set up the indoor address from the interface P. If the power supply of the outdoor unit has been firstly turned on, [E19] appears on the 7-segment display on the interface P. However it is not an error. Check that [L08] is displayed on 7-segment display [B] on the interface P.
L Indoor address unset up If the address setup operation has already finished in service time, etc, the above check code is not displayed, and only [U1] is displayed on 7-segment display [A]. Cautions 1. It requires approx. However in some cases, it may require maximum 10 minutes. It is unnecessary to operate the air conditioner for address setup. Manual address setup is also available besides automatic setup. Automatic address: Setup from SW15 on the interface P.
Be sure that the setup operation may differ in group control or central control. Note Address cannot be set up if switches are not operated. Using 7-segment display function, check the system information of the scheduled system. This check is executed on the interface P. Display check on remote controller In case of wired remote controller Check that a frame as shown in the following left figure is displayed on LC display section of the remote controller.
Interface P. If a frame is not displayed as shown in the above right figure, the power of the remote controller is not normally turned on. Therefore check the following items. Tel: 7-segment display SW01 www. Set up the address according to the following setup procedure. Set up address after wiring work. If turning on the power in the reverse order, a check code [E19] Error of No. When a check code is output, turn on the power again. It requires maximum 10 minutes Usually, approx.
To set up an address automatically, the setup at outdoor side is necessary. Address setup cannot be performed by power-ON only. To set up an address, it is unnecessary to operate the air conditioner. Automatic address : Setup from SW15 on the interface P. In group operation and in time without remote controller Automatic Address Setup Without central control : To the address setup procedure 1 With central control : To the address setup procedure 2 81 Example In case of central control in a single refrigerant line In case of central control over refrigerant lines Address setup procedure To procedure 1 To procedure 2 Cable systematic diagram Indoor Remote controller Central remote controller Indoor Remote controller Outdoor Indoor Central remote controller Indoor Remote controller Address setup procedure 1 1.
After approx. L08 U. Push SW15 and start setup the automatic address. When perform a central control, connect a relay connector between [U1, U2] and [U3, U4] terminals in the outdoor unit. Using SW13 and 14 on the interface P. At shipment from factory: Set to Address 1 Note Be careful not to duplicate with other refrigerant line.
In this case, change the group address from the wired remote controller for only one header unit is set up. Do not change setup. Check that the relay connectors between [U1U2] and [U3U4] terminals are come out in all the outdoor units to which the central control is connected. At shipment from factory: No connection of connector 3. Procedure 4. How to set up resistance of the end terminal Outdoor unit interface P. Then set up the central control address. For the central control address setup, refer to the Installation manual of the central control devices.
LCD changes to flashing. Line address Turn on the power. OK when display goes on. Setup operation finished. Status returns to normal stop status. Data Relay connector — NOTE — Never connect a relay connector until address setup for all the refrigerant lines finishes; otherwise address cannot be correctly set up. Tel: Operation procedure R. Indoor address 7 ON SW30 OFF Relay connector U1 U2 In the above example, under condition of no inter-unit wire of the remote controller, set the address after individual connecting of the wired remote controller.
Match it with the line address on the interface P. The address 29 and 30 cannot be set up in the outdoor unit. An outdoor unit is selected, the indoor unit numbers in the same refrigerant line are successively displayed, and then its indoor unit fan is turned on. Push UNIT button. Disappears after several seconds The displayed unit No indicates the line address and indoor address. If there is other indoor unit connected to the same remote controller Group control unit , other unit No.
UNIT No. All the indoor units in group control stop. Using SET button, determine the selected line address. Every pushing UNIT button, the indoor unit numbers in the identical pipe are successively displayed. Operation while the air conditioner stops Every pushing UNIT button, the indoor unit numbers in the group control are successively displayed. Using UNIT address. Select outdoor unit. In group control, select an indoor unit No. Using the setup temp. Repeat the proceto and change the indoor address so dure that it is not duplicated.
After the above change, push confirm the changed contents. If it is acceptable, push confirmation. Firstly, the line 1, item code AC Address Change is displayed. For the setup procedure, refer to the abovementioned address setup from the remote controller. Method 2 buttons, select the line address. First the current indoor address is displayed on the setup data. Line address is not displayed. Turn off the power of the refrigerant line to be returned to the status at shipment, and change the outdoor unit to the following status.
If it has been already removed, leave it as it is. If it has been already ON, leave it as it is. Central control device Push SET button to determine the setup data. Only fan of the selected indoor unit operates. Repeat the procedure to and change all the indoor addresses so that they are not duplicated.
All the displays on LCD go on. CL 5, 7 To finish the setup Here, if the unit No is not called up, the outdoor unit in this line does not exist. Push CL button, and then select a line according to procedure. Check again the relay connector between [U1U2] and [U3U4] terminals.
NOTE Be careful that the other refrigerant line address may be also cleared if clearing operation is not correctly executed. After clearing of the address, set up an address again. If set up the indoor address of which address is undefined accompanied with extension of indoor units, replacement of P. When the central control system is connected, check the following setup has finished after address setup. Method 1 Set up an address individually from a wired remote controller.
Set up an address only to the unit of which address is undefined. The addresses are allocated from the low number. Figure below 1. Remove the relay connector between [U1U2] and [U3U4]. Turn on SW on the interface P. Execute the following operation on the interface P. Terminator resistor Line address Check 1 Is relay connector of the outdoor unit connected after address setup? NOTE The above table does not describe all the electric cablings.
For details, refer to each installation manual for outdoor unit, indoor unit, remote controller, and optional devices. Return the SW01, 02, 03 setup as before. Return the following setup as before. Troubleshooting in Test Operation If the phenomena appear, such as a check code is output or the remote controller is not accepted in power-ON after cabling work or in address setup operation, the following causes are considered.
Turn on the power again. After address setup Check SW30 bit 2 of the outdoor unit. No connection between multiple refrigerant lines: SW30 bit 20N Connection between multiple refrigerant lines: SW30 bit 2 of the connected outdoor unit is turned on only in one line.
After address was decided, all the indoor units do not correctly response after power-ON in outdoor unit. Communication line between outdoor unit and the leading indoor unit Check influence of communication noise. Address setup error Set up address again. Units except those displaying E04 are duplicated. Except group displaying E04 Duplication of indoor addresses. Address No in which sub-code of the check code are duplicated Set up address again.
There is none of outdoor terminal resistance, or there are two or more resistances. After address setup, when terminal resistance setup is changed after power-ON. Check SW30 bit 2 of the outdoor unit. After address setup, communication from all the indoor units interrupted under condition that a normal operation can be performed. Exceeded No of connected indoor units or exceeded capacity. Adjust No of connected indoor units or capacity. Only when outdoor address was manually set up Do not use a manual setup for outdoor address.
Set up SW 13 and 14 on the interface P. L06 L08 There are two or more indoor units set up with priority. Set up address again. Operation from remote controller is not accepted and a check code is displayed on 7-segment display of the interface P.
Remote controller status 7-segment display of outdoor unit No response L08 E Cause Countermeasures Line addresses and indoor addresses of all the connected indoor units are unset. Set up addresses. There is no outdoor unit of group control. Set up group address. Indoor unit power is not turned on. ON 1 2 Correct wiring. SW30 There is none of outdoor terminal resistance, or there are two or more resistances. Before address setup Check SW30 bit 2 of the outdoor unit.
No connection between multiple refrigerant lines: SW30 bit 2 0N Connection between multiple refrigerant lines: SW30 bit 2 of the connected outdoor unit is turned on only in one line.
|Ac servo driver a1 svd30||Power ON Set the display select switches on the interface P. Lindgren, [ 79 ] Salobir, [ 80 ] Jood, [ yamaha silent guitar slg200n ]. Ungvari Z. Detection of leading edge home position of paper in the lower roll unit. Perfusion studies on CT and MRI showed that small areas of hypoperfusion article source not a complete absence of it are visible in some patients with a confirmed RSSI on follow-up imaging, including areas of potentially viable tissue ischemic penumbra [ 4344 ], in contrast with the hypothesis of a complete flow obstruction, without compensation in a terminal arterial territory. Remove the air filter by pulling it toward you.|
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|Akweb||Subcortical infarcts in animal models produced by microembolism [ 6 ]. Conveys paper from the roll unit. Check again cautious points on wiring. Status that card is inserted in the card switch box 2 Outside contact OFF : If the indoor unit is operating, it is stopped forcedly. Control of the original motor and detection of original insertion and paper. However, this sound may not be heard at a place where outside sound takes precidence.|
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Some wiring of the servo drive, stepper drive for compare Aluminum mounts machined while holding the servo with 3D printed parts. Practical Renaissance. The video shows the basic connection of the ATO servo motor kit and how to initialize the servo driver and how to set the JOG If you would like to see this and other projects to commence faster, please consider supporting me on Ground connection! Thanos 6DOF motion sim electronics.
It can go faster of course for lower The white shielded power cable is still using the original aviation type connector. Technical animation: How a Servo Motor works learnchannel. In this animation you get the functioning of a servo motor and how the components of a servo drive system work together. From the AASDA servo enclosure in progress For more information, please The position can be adjust by the AC driver. New Items Used 63 Items Please provide a valid price range.
Buying Format. All Listings. Accepts Offers. Buy It Now. Item Location. Canada Only. North America. Shipping Options. Free International Shipping. Local Pickup. Free Local Pickup. Show only. Free Returns. Returns Accepted. Authorized Seller. Completed Items.
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I performed some tests on a chinese aliexpress 80ST-M 2. It can be used for a As promised in the previous video, connect the servo ST-M Also, in addition took ST-M First time connecting a servo motor. There is a lot of settings, but if u just want it to run or use it as a stepper motor, It is not much Hey In this video I demonstrate how the pulse frequency correlates with the electronic gear of the servo motor. Basically, the I'll show how to wire it up and set the parameters on Chinese servo 1.
Some wiring of the servo drive, stepper drive for compare Aluminum mounts machined while holding the servo with 3D printed parts. Practical Renaissance. The video shows the basic connection of the ATO servo motor kit and how to initialize the servo driver and how to set the JOG If you would like to see this and other projects to commence faster, please consider supporting me on New Items Used 63 Items Please provide a valid price range.
Buying Format. All Listings. Accepts Offers. Buy It Now. Item Location. Canada Only. North America. Shipping Options. Free International Shipping. Local Pickup. Free Local Pickup. Show only. Free Returns. Returns Accepted. Authorized Seller. Completed Items. Sold Items. Authenticity Guarantee. More filters Condition Any Condition. Gallery View Customize. Postal code. Shop on eBay Opens in a new window or tab Brand New. Free returns. NEMA32 2. Delta 1. Last one.
AC servo motor driver A1-SVD10 A1-SVD15 A1-SVD20 A1-SVD25 A1-SVD30 Controller HZ V ; Motor Type:AC Motor ; Certification:NONE ; Origin:CN. 2KW servo motor kit ST-M+A1-SVD30 driver diameter mm V NM rpm. US $ US $ %. US $ Coupons For You. Get coupons. Thank you very much for your buying Panasonic AC Servo Motor Driver,A-series. • Before use, read through this manual to ensure proper use.