Microembolic Signals In Patients Research Articles

Approaches to classification of microembolic signals in patients recovering from ischemic stroke

Introduction. Microembolus detection by transcranial Doppler (TCD) is the only non-invasive modality for visualization of cerebral embolism. Currently, there is no unified classification of recorded microembolic signals (MES) that could be used in clinical practice.
 The aim of the study is to investigate biophysical MES parameters in patients with ischemic stroke, as well as to assess approaches to microemboli differentiation by structure and origin to improve the diagnostic accuracy of the method and to reduce the risk of recurrent ischemic events.
 Materials and methods. The inclusion criterion was TCD-detected signs of MES. We analyzed the data of 28 patients with ischemic stroke (9 women and 19 men; mean age was 58 years 13). We recorded power, duration, and frequency for each MES, and calculated an energy index.
 Results. A total of 938 MES were reported. In patients with cardioembolic stroke and all other pathogenetic stroke subtypes, biophysical parameter limits were as follows: 14.65 dB for the average power, 9.45 ms for the average duration, and 0.16 J for the average energy index. For patients with atrial fibrillation, characteristic MES power was found to be 13 dB. The MES frequency limit was determined to be 650 Hz for microemboli differentiation by acoustic density.
 Conclusion. The data obtained can be used to further search for optimal limit ranges for biophysical parameters of various MES in order to establish a single MES classification, which will increase the diagnostic value of microembolus detection by TCD in stroke treatment practice.

Microembolic Signals in Arteries of the Base of the Brain after Ischemic Stroke.

Embolic strokes make up a significant proportion of acute cerebrovascular accidents. Doppler blood flow monitoring with microembolodetection allows suggesting the embolic nature of cerebral infarction. The aim of this study was to identify factors associated with the presence of microembolic signals in patients with ischemic stroke. The study included 515 patients, microembolic signals were detected in 48 (9.3%) of them. According to multispiral CT angiography, significant differences in patients with and without microembolic signals were found for wall thickness of both common carotid arteries and for left internal carotid artery (p<0.05). Factor analysis revealed a variable that reflects the severity of left carotid arteries atherosclerosis, which was a significant predictor of registration of the microembolic signals (p=0.016).

Cerebral Microembolism in Intracerebral Hemorrhage: A Prospective Case–Control Study

Small and remote acute ischemic lesions may occur in up to one-third of patients with spontaneous intracerebral hemorrhage (ICH). Possible mechanisms include cerebral embolism, small vessel disease, blood pressure variability and others. The embolic mechanism has not been adequately studied. Using transcranial Doppler (TCD), we assessed the incidence of spontaneous microembolic signals (MESs) in patients with acute ICH. Twenty acute ICH patients were prospectively evaluated within 48h of hospital admission. Clinical and imaging data were collected. Continuous TCD monitoring was performed in both middle cerebral arteries for a one-hour period on days 1, 3 and 7 of hospital admission. Monitoring was performed in the emergency room, ICU or ward, according to patient location. We compared the frequency and risk factors for MES in patients with ICH and in 20 age- and gender-matched controls without history of ischemic or hemorrhagic stroke. The mean age was 57.5 ± 14.1years, and 60% were male. MESs were detected in 7 patients with ICH and in one control patient without ICH (35% vs 5%, p = 0.048). The frequency of MES on day 1 was 15% (3 of 20 patients), on day 3, 26% (5 of 19 patients) and on day 7, 37.5% (3 of 8 patients). Among patients with ICH, those with MES had a tendency to higher frequencies of dyslipidemia (83% vs 33%, p = 0.13) and lobar location of hemorrhages (71% vs 30%, p = 0.15). Two out of 6 patients with ICH who also underwent MRI had remote DWI lesions, of whom one showed MES on TCD. Micro-embolic signals occur in over one-third of patients with ICH. Further research is needed to identify the sources of cerebral microembolism and their relationship with small acute infarcts in ICH.

Plasma Osteoprotegerin Correlates with Stroke Severity and the Occurrence of Microembolic Signals in Patients with Acute Ischemic Stroke.

Background Instability of atherosclerotic plaques is associated with the occurrence of stroke. Microembolic signals (MESs) are an indicator of unstable plaque. A relationship between plasma osteoprotegerin (OPG) and ischemic stroke has already been identified. The aim of this study was to investigate whether plasma OPG levels have a relationship with MESs and to evaluate the feasibility of OPG as a biomarker of stroke severity and occurrence of MESs. Methods Our study consisted of 127 patients with large artery atherosclerosis stroke and 56 controls. Patients were classified into subgroups based on stroke severity and the occurrence of MESs. MES-monitoring was performed for 60 min using transcranial Doppler within 72 h of stroke onset. Stroke severity at admission was assessed by the National Institutes of Health Stroke Scale. Results Plasma OPG levels were significantly associated with stroke, MESs, and stroke severity at admission (adjusted OR [95% CI]: 1.002 [1.001–1.003] p < 0.001; 1.002 [1.001–1.003] p = 0.001; 1.001 [1.000–1.002] p = 0.028). When plasma OPG levels were used to determine the stroke severity, the area under the receiver-operating characteristic curve (AUC) was 0.734 (95% CI: 0.625-0.843) based on a cutoff value of 1998.44 pg/ml; the sensitivity and specificity of this test were 80.6% and 65.6%, respectively. Furthermore, when the levels of OPG were used to distinguish the presence of MESs, the AUC was 0.766 (95% CI: 0.672-0.860); the cutoff value was 2107.91 pg/ml. The sensitivity of this cutoff value was 68.8% and the specificity was 73.7%. Conclusions Plasma OPG levels correlate with stroke severity and the occurrence of MESs.

Transcranial Doppler findings in antiphospholipid syndrome.

Transcranial Doppler is a method that enables the assessment of different cerebral hemodynamic parameters. It also allows for the evaluation of the presence of right-to-left circulation shunts (RLS) and for the detection of microembolic signals (MESs), which might be associated with an increased risk of cerebrovascular events. For instance, the presence of MESs on transcranial Doppler in patients with systemic lupus erythematous (SLE) and antiphospholipid syndrome (APS) is associated with an increased risk of stroke. Therefore, transcranial Doppler could be a useful tool for stroke risk stratification in these patients. Our objective was to evaluate transcranial Doppler cerebral mean blood flow velocities as well as the presence of MESs and RLS in patients with antiphospholipid syndrome and SLE. Twenty-two patients with primary APS (PAPS), 24 patients with secondary APS (SAPS), 27 patients with SLE without APS and 21 healthy controls were evaluated. Clinical and epidemiological data were compiled from medical charts, and all subjects underwent transcranial Doppler examination with breath-holding index calculation. Both middle cerebral arteries were monitored for 60 min for the detection of MESs. RLS was investigated with agitated saline injected as a bolus. There were no significant differences in mean blood flow velocities among the groups. MESs were more frequently found in patients with SLE when compared with controls and patients with APS (SLE: 17.4%, SAPS: 4.3%, PAPS: 0%, controls: 0%, p = 0.03). Anticoagulant therapy was more frequently used in the APS group (PAPS: 81.8%, SAPS: 75.2%, SLE: 1.7%, p < 0.001). Patients with APS had a higher frequency of RLS when compared with volunteers (63.6% versus 38.1%, p = 0.05). Breath-holding index values tended to be lower in patients with SAPS than in control subjects and patients with PAPS and SLE ( p = 0.06). Patients with APS had a higher frequency of RLS than healthy controls. This finding alerts to the importance of cardiac investigation in patients with stroke and APS, because further therapies such as RLS occlusion might eventually add protection. The higher frequency of MES in patients with SLE could suggest an effect of anticoagulant therapy on MES prevention, more frequently used in patients with APS.

The Clinical Implication of Transcranial Doppler Detection of Microembolic Signals in Patients with Heartmate II.

We aimed to elucidate the clinical relevance of transcranial Doppler (TCD) in the detection of microembolic signals in patients with Heartmate II (HM-II). Twenty patients with HM-II underwent TCD examinations, and microembolic signals were rarely detected in stable patients. However, they were detected in patients with hemolysis and/or thromboembolic events. Further, TCD examination under oxygen inhalation revealed that, both, solid emboli and gaseous emboli exist in patients with HM-II.

Statin Pretreatment and Microembolic Signals in Large Artery Atherosclerosis.

Background and Purpose- Scarce data indicate that statin pretreatment (SP) in patients with acute cerebral ischemia because of large artery atherosclerosis may be related to lower risk of recurrent stroke because of a decreased incidence of microembolic signals (MES) during transcranial Doppler monitoring. Methods- We performed a systematic review and meta-analysis of available observational studies reporting MES presence/absence or MES burden, categorized according to SP status, in patients with acute cerebral ischemia because of symptomatic (≥50%) large artery atherosclerosis. In studies with partially-published data, authors were contacted for previously unpublished information. We also performed a sensitivity analysis of studies with data on MES burden categorized according to SP status, and an additional subgroup analysis in patients receiving higher-dose SP (atorvastatin 80 mg or rosuvastatin 40 mg daily). Results- Seven eligible study protocols were identified (610 patients, 54% with SP). SP was associated with a reduced risk of MES detection during transcranial Doppler monitoring (risk ratio=0.67; 95% CI, 0.45-0.98), with substantial heterogeneity between studies ( I2=52%). In studies reporting MES burden (n=4), a significantly lower number of MES were identified in patients with compared with those without SP (mean difference=-0.92; 95% CI, -1.64 to -0.19), with no evidence of heterogeneity between studies ( I2=49%). Subgroup analysis revealed that higher-dose SP reduced the risk of detecting MES (risk ratio=0.23; 95% CI, 0.06-0.88), with no evidence of heterogeneity between studies ( I2=0%). Conclusions- SP seems to be associated with a lower incidence and burden of MES in patients with acute cerebral ischemia because of large artery atherosclerosis.

Plasmatic biomarkers of inflammation correlate with 18FDG-PET-CT and microembolic signals in patients with carotid stenosis

Vessel Plus is an open acccess journal, which publishes articles related to vascular diseases, including acute respiratory distress syndrome, aneurysm, atherosclerosis, hypertension, stroke, peripheral vascular or pulmonary vascular diseases, etc.

Prevalence of Microembolic Signals in Patients with Cerebral Ischemic Events (P5.211)

Prevalence of Microembolic Signals in Patients with Cerebral Ischemic Events (P5.211)

Inhibition of Factor XIa Reduces the Frequency of Cerebral Microembolic Signals Derived from Carotid Arterial Thrombosis in Rabbits.

Factor XI (FXI) is an integral component of the intrinsic pathway of the coagulation cascade and plays a critical role in thrombus formation. Because its role in the pathogenesis of cerebral microembolic signals (MES) is unclear, this study used a potent and selective small molecule inhibitor of FXIa, compound 1, to assess the effect of FXI blockade in our recently established preclinical model of cerebral MES induced by FeCl3 injury of the carotid artery in male New Zealand White rabbits. Ascending doses of compound 1 were evaluated simultaneously for both carotid arterial thrombosis by a Doppler flowmeter and MES in the middle cerebral artery by a transcranial Doppler. Plasma drug exposure and pharmacodynamic responses to compound 1 treatment were also assessed. The effective dose for 50% inhibition (ED50) of thrombus formation was 0.003 mg/kg/h compound 1, i.v. for the integrated blood flow, 0.004 mg/kg/h for reduction in thrombus weight, and 0.106 mg/kg/h for prevention of MES. The highest dose, 3 mg/kg/h compound 1, achieved complete inhibition in both thrombus formation and MES. In addition, we assessed the potential bleeding liability of compound 1 (5 mg/kg/h, i.v., >1250-fold ED50 levels in arterial thrombosis) in rabbits using a cuticle bleeding model, and observed about 2-fold (not statistically significant) prolongation in bleeding time. Our study demonstrates that compound 1 produced a robust and dose-dependent inhibition of both arterial thrombosis and MES, suggesting that FXIa blockade may represent a novel therapeutic strategy for the reduction in MES in patients at risk for ischemic stroke.

(658) - The Clinical Relevance of Transcranial Doppler Detection of Micro-Embolic Signals in Patients with Heartmate II

(658) - The Clinical Relevance of Transcranial Doppler Detection of Micro-Embolic Signals in Patients with Heartmate II

Brain unidentified bright objects ("UBO") in systemic lupus erythematosus: sometimes they come back. A study of microembolism by cMRI and Transcranial Doppler ultrasound.

The objectives of this report are to assess the occurrence of microembolic signals (MES) detected by transcranial Doppler ultrasound (TCD) in systemic lupus erythematosus (SLE) patients with (NPSLE) and without (SLE) neuropsychiatric involvement, and to verify the correlation between MES, clinical characteristics, especially the patent foramen ovale (PFO), and the presence of punctuate T2-hyperintense white matter lesions (WMHLs) detected by conventional magnetic resonance imaging (cMRI). A TCD registration to detect MES from the middle cerebral artery was carried out in SLE and NPSLE patients after exclusion of aortic and/or carotid atheromatous disease. In all patients conventional brain magnetic resonance imaging (cMRI) and transesophageal echocardiography were performed. Patients were stratified in two groups, with and without WMHLs, and compared. Twenty-three SLE patients (16 NPSLE and seven SLE) were enrolled in the study. Overall MES were detected in 12 patients (52.1%), WHMLs were detectable in 15 patients (13 NPSLE and two SLE) while eight patients had normal cMRI (three NPSLE and five SLE). Matching TCD ultrasound and neuroimaging data, MES were detected in 10 (nine NPSLE and one SLE) out of 15 patients with WHMLs and in only two out of eight patients (two NPSLE and six SLE) with normal cMRI, both with NP involvement. A PFO was confirmed in all cases of MES detection. MES are frequent findings in SLE patients, especially in those with focal WMHLs detected by cMRI and correlating with PFO. These findings should be taken into account and suggest caution in the interpretation of cMRI pictures along with a careful evaluation of MES in patients with cMRI abnormalities that should be included in the workup of SLE patients.

Dual Antiplatelets Reduce Microembolic Signals in Patients with Transient Ischemic Attack and Minor Stroke: Subgroup Analysis of CLAIR Study

Short course of dual antiplatelet therapy for early secondary prevention is a promising treatment for patients with minor stroke or transient ischemic attack at high risk of recurrence. We examined the efficacy and safety of dual antiplatelets in patients with transient ischemic attack or minor stroke, defined as National Institute of Health Stroke Scale scores 0-3, in a subgroup analysis of Clopidogrel plus aspirin versus Aspirin alone for Reducing embolization in patients with acute symptomatic cerebral or carotid artery stenosis (CLAIR) study. Microembolic signals on transcranial Doppler monitoring was used as surrogate marker for recurrent stroke risk. Patients with ≥1 microembolic signals at baseline were randomized to receive dual therapy (aspirin 75-160 mg daily and clopidogrel 300 mg day 1 then 75 mg daily) or monotherapy (aspirin 75-160 mg daily) for seven-days. Sixty-five of 100 patients recruited had transient ischemic attack or minor stroke: 30 received dual therapy and 35 received monotherapy. Mean onset-to-randomization was 2·3 days in dual therapy group and 3·2 days in monotherapy group (P = 0·03). At day 7, the proportion of patients with ≥1 microembolic signals was 9 of 29 patients in dual therapy group and 18 of 34 patients in monotherapy group (adjusted relative risk reduction 41·4%, 95% CI 29·8-51·1, P < 0·001). The median number of microembolic signals on day 7 was 0 in dual therapy group and 1·0 in monotherapy group (P = 0·046). No patients had intracranial or severe systemic hemorrhage. Early dual therapy with clopidogrel and aspirin reduces microembolic signals in patients with minor ischemic stroke or transient ischemic attack, without causing significant bleeding complications.

Abstract W P176: Relationship Between Right-to-Left Shunting and Microembolic Signals on Transcranial Doppler Monitoring

Background: Transcranial doppler-monitoring (TCM) has been used to identify patients at risk for embolic stroke and aids in identification of stroke mechanism. Limited data exists on the occurrence of microembolic signals (MES) on TCM and the presence of right-to-left shunting (RLS), most commonly through a patent foramen ovale. Our objective was to determine if a relationship exists between the presence of a RLS on transcranial doppler-bubble (TCB) and MES on TCM, and if the degree of shunting correlated with increased number of MES. Methods: A retrospective chart review was conducted of 113 inpatients that underwent both TCB for the detection of a RLS and TCM during their admission for ischemic stroke at the Cleveland Clinic between 2011 and 2012. TCM was performed for 20 minutes in all patients. Both TCM and TCB used standardized protocols and machines. Data collected included demographics, presence of a shunt, and stroke mechanism. Results: Mean age of the study cohort was 57.9 years and 46.9% were female. RLS on TCB was found in 30.1% of patients and MES were seen on TCM in 33.6% of patients. The occurrence of MES was similar in patients with and without RLS (38.2% vs. 31.6% respectively) (p=0.50). In patients with undetermined stroke mechanism and RLS, there was a trend towards higher occurrence of MES (42.9% vs 30.8%, p=0.35). No significant difference was seen between the occurrence of MES and degree of shunting according to Spencer Grades I-IV (p=0.48). Patients with MES and RLS had an insignificantly greater number of MES than patients without RLS (59.8 vs 10.8. p=0.33). This difference in the number of MES was more pronounced in patients with undetermined stroke etiology (73.1 vs 14.4, p=0.42). Conclusions: There was no overall relationship between RLS and MES on TCM. However, the number of MES in patients with positive TCM was greater in those with a RLS compared to those without RLS, particularly in patients with undetermined stroke mechanism. Although, more data is needed, in patients with strokes of undetermined etiology, the presence of MES on TCD may suggest the presence of a RLS, especially if the number of MES is high.

The Effectiveness of Dual Antiplatelet Treatment in Acute Ischemic Stroke Patients with Intracranial Arterial Stenosis: A Subgroup Analysis of CLAIR Study

Dual antiplatelet therapy with clopidogrel and aspirin reduces the presence and number of microembolic signals in patients with large artery disease. However, whether it is effective in patients with intracranial disease alone remains uncertain. We performed a subgroup analysis of the The CLopidogrel plus Aspirin for Infarction Reduction (CLAIR in acute stroke or transient ischemic attack patients with large artery stenosis and microembolic signals) study of only patients with intracranial occlusive disease, excluding those with extra cranial disease. CLAIR was a randomized-controlled, open-label, multicenter clinical trial with blinded outcome evaluation, which recruited patients with symptoms of ischemic stroke or transient ischemic attack within seven-days of onset, with large artery stenosis verified by transcranial Doppler and carotid ultrasound, and with microembolic signals detected by transcranial Doppler recording. All patients were randomized to receive clopidogrel plus aspirin daily for seven-days (dual treatment), or aspirin alone for seven-days (monotherapy). Repeated transcranial Doppler recordings for microembolic signals were made on day one, two, and seven. This subgroup study only analyzed the patients with purely intracranial large artery disease and excluded those with extra cranial stenosis. There were 70 patients recruited with purely intracranial stenosis, 34 in the dual treatment group and 36 in the monotherapy group. The proportion of the patients with positive emboli at day seven in the dual treatment group was significantly lower than that in the monotherapy group (relative risk reduction 56·5%, 95% confidence interval 2·5-80·6; P = 0·029). The number of emboli in the dual treatment group decreased significantly at day two (P = 0·043) and day seven (P = 0·018) compared with the monotherapy group. After adjustment for the number of emboli at day one, the effect of dual treatment was still significant for the reduction of presence (relative risk reduction 56·0%; 95% confidence interval 5·4-79·6; P = 0·036) and number (adjusted mean difference -0·9; 95% confidence interval -1·5 to -0·3; P = 0·004) of positive emboli at day seven. Dual treatment with clopidogrel and aspirin for seven-days is more effective than aspirin alone to reduce microembolic signals in patients with intracranial arterial stenosis.

Clopidogrel Load for Emboli Reduction in Patients With Symptomatic Carotid Stenosis Undergoing Urgent Carotid Endarterectomy

Microembolic signals (MES) on transcranial Doppler are an independent risk factor for recurrent stroke in patients with extracranial symptomatic/asymptomatic carotid artery stenosis (CARAS). Clopidogrel load (300 mg) combined with dual antiplatelet therapy has been shown to reduce MES in patients with symptomatic CARAS. We sought to determine feasibility of clopidogrel load in decreasing asymptomatic embolization in patients with symptomatic CARAS undergoing urgent carotid endarterectomy within the first 2 weeks from the index event. Subjects and Consecutive patients with symptomatic CARAS (70%-99%) and presence of MES on 1-hour baseline (<24 hours from the index event) transcranial Doppler monitoring of ipsilateral middle cerebral artery were treated with clopidogrel load followed by clopidogrel (75 mg)±aspirin (100 mg) during the elapsed time period between hospital admission and urgent carotid endarterectomy at 3 tertiary-care stroke centers. Repeat 1-hour transcranial Doppler monitoring was performed the day before surgery. Bleeding complications during surgery and recurrent strokes or transient ischemic attacks during the first month of ictus were prospectively recorded. A total of 11 symptomatic CARAS patients (mean age, 66±7 years; 73% men; 64% acute ischemic strokes) were treated with clopidogrel load followed by dual (67%) or single (33%) antiplatelet therapy. MES count was significantly reduced between baseline (median count, 8 MES/h; interquartile range, 6-19) and repeat transcranial Doppler monitoring (0 MES/h; interquartile range, 0-3; P=0.003). No bleeding complications, recurrent strokes, or transient ischemic attacks were documented. Our pilot observational study provides preliminary nonrandomized data regarding the potential efficacy of clopidogrel load to reduce asymptomatic embolization in patients with symptomatic CARAS before urgent carotid endarterectomy.

Microembolic Signals in Patients with Acute Nonembolic Stroke

The nature of microembolic signals (MES) in patients without apparent sources of embolism remains elusive. We hypothesize that MES in acute stroke patients without an embolic source may represent a transient phenomenon related to blood rheology or clot dissolving, in which case the characteristics of such MES would differ from those with definitive sources of emboli. We compared the intensity and duration of 250 MES in 62 acute nonembolic stroke patients (stroke group) and 217 MES in 57 patients with asymptomatic carotid stenosis (≥50%; carotid group). The duration of MES was significantly different between the 2 groups (24.86 ± 0.89 ms in the carotid group v 18.8 ± 0.83 in the stroke group; P < .001). When comparing the groups for MES with an intensity higher than 6 dB, a highly significant difference in the duration of MES was found (27.87 ± 1.26 ms in the carotid group v 18.57 ± 1.29 ms in the stroke group; P < .0001). A strong linear relationship between the duration and intensity of MES was found for the carotid group, but not for the stroke group. There are significant differences between the characteristics of MES in acute stroke patients as compared with MES in patients with carotid plaques. There is a strong correlation between the intensity and duration of MES from a definitive embolic source, which is absent from MES in patients with nonembolic stroke. These findings may point to the different mechanisms of MES origin in the examined groups.

The contribution of microembolic signals (MES) detection in cardioembolic stroke

Summary Background Cardioembolic stroke accounts for about one third of all strokes. Microembolic signals (MES) are frequently found in patients with acute stroke. The role of MES in cardioembolic stroke is less well investigated. Methods Medline based literature review of clinical trials linking MES and stroke with cardiac sources of various risks. Results MES are a rare finding in patients with cardioembolic stroke as well as in sources of potential cardiac embolism (e.g. myocardial infarction, atrial fibrillation, left ventricular thrombus). The low number of patients with MES and the low number of MES during the investigation times leads to a limited statistical power of positive and negative findings. MES in patients with artificial heart valves and the DeBakey left ventricular assist device (LVAD) are predominantly gaseous and do not correlate with stroke risk. In patients with the Novacor LVAD, MES strongly correlate with stroke risk. Conclusion Currently, the role of MES in cardioembolic stroke is only limited due to both, the low prevalence of MES and the number of MES per investigation. Larger studies would be needed to strengthen this role.

Microembolic signals in patients with prosthetic valves: Relationship with the degree of anticoagulation

Microembolic signals (MES), detectable by transcranial Doppler, are usually observed in patients with prosthetic valves. The clinical relevance of this finding is still unsettled. We evaluated the presence and number of MES and the degree of anticoagulation in 47 patients submitted to aortic or mitral valve replacement with mechanical prostheses at least 6 months before, with normal cardiac function and no other possible cardiac or carotid sources of cerebral embolism. Each patient was submitted to transcranial Doppler of both middle cerebral arteries for 45 minutes. Detection of MES was based on the double presence of the high intensity signal at two different depths with temporal delay, using a dedicated software with visual and acoustic confirmation. MES were observed in 18 patients (38.3%). Among them, 9 (19.1%) had 1–2 MES, and 9 (19.1%) had 3 or more MES. Twenty patients had an International Normalized Ratio (INR) ? 2.0, patients with the highest number of MES having the lowest INR (ANOVA: F = 4.21, p <0.01). No differences in MES number were observed between patients with either mitral or aortic valve replacement. The finding of a relationship between the number of MES and the degree of anticoagulation raises the possibility that, in patients with prosthetic valves, MES may have a greater clinical relevance than previously thought.

Microembolic Signals in Patients with Cryptogenic Stroke with or without Patent Foramen Ovale

To evaluate the incidence, frequency, and contributing factors of microembolic signals (MESs) in patients with cryptogenic stroke with or without patent foramen ovale (PFO). Transcranial Doppler monitoring for MESs detection was performed for 62 patients with acute cryptogenic stroke with PFO (PFO(+)) and 34 patients with acute cryptogenic stroke without PFO (PFO(-)). The incidence of MESs was not significantly higher in PFO(+) patients (17/62, 27.4%) in comparison to PFO(-) patients (6/34, 17.6%; odds ratio 1.76, 95% confidence interval 0.62-5.00; P = .327). The frequency of MESs in PFO(+) patients was statistically higher than that of PFO(-) patients (0.70 ± 1.47 v 0.23 ± 0.55; P = .026). MESs was presented with higher incidence in a subgroup of patients suffering from both patent foramen ovale and atrial septal aneurysm (P = .044). The likelihood of PFO as a source of MESs is higher when associated with atrial septal aneurysm.