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Biomedical subjects

Masahiro Yasaka

Publications and source records attributed to Masahiro Yasaka.

At least 19 recordsLinked to original sources
PubMed2007

[Prevention of brain infarction in patients with atrial fibrillation].

The patients with cardioembolic stroke sometimes suffer from severe neurological deficit and from recurrent strokes. Since atrial fibrillation, especially non-valvular atrial fibrillation (NVAF) is associated with over half of the cardioembolic strokes, the prevention of cardioembolic stroke in patients with NVAF is important. There have been some reports about how to prevent stroke. They have indicated that the best medication for preventing from stroke was anticoagulation by warfarin. Therefore, the guidelines recommended the patients with NVAF to take warfarin. In case with the older patients under 70 years, prothrombin international normalized ratio (PT-INR) should be kept from 2.0 to 3.0. On the other hand, if the patients with NVAF are over 70 years, PT-INR has to be controlled from 1.6 to 2.6. Before extraction of a tooth, anticoagulation should not be call off.

Age Factors↗
PubMed2006

Factors associated with occurrence of the intraleft atrial nonsmoke spontaneous individual contrast phenomenon after a Valsalva maneuver during transesophageal echocardiography.

Nonsmoke spontaneous individual contrast (NSSIC) is a phenomenon that is a contrast effect appearing from the right pulmonary vein to the left atrium just after a Valsalva maneuver in a transesophageal echocardiography study without administration of any contrast medium. The goal of this study was to characterize factors associated with occurrence of NSSIC. Transesophageal echocardiography was performed in 228 consecutive patients to determine the presence or absence of the patent foramen ovale and valvular disease and various patient characteristics and laboratory data. NSSIC was demonstrated in 109 (47.8%) of 228 patients. Factors associated with occurrence of NSSIC included younger age, male gender, smoking habit, taller height, heavier weight, higher hematocrit, higher plasma level of fibrinogen, lower D-dimer levels and presence of mitral valve strand. Multiple logistic regression analysis indicated that higher hematocrit and plasma levels of fibrinogen were most closely associated with the presence of NSSIC. Thus, NSSIC may occur secondary to specific blood rheologic factors during the Valsalva maneuver.

Age Factors↗
PubMed2006

Bottle neck sign of the proximal portion of the internal carotid artery in moyamoya disease.

OBJECTIVE: We investigated morphologic features of the extracranial internal carotid artery (ICA) by carotid ultrasonography in patients with moyamoya disease. METHODS: We performed conventional carotid ultrasonography and transoral carotid ultrasonography on 19 ICAs in 10 patients with moyamoya disease (moyamoya group) and 28 ICAs in 14 control subjects (control group). We evaluated whether the diameter was greatly reduced at the proximal portion of the ICA above the bulbus, like a champagne bottle neck, to be less than half that of the common carotid artery and whether the diameter of the ICA was smaller than that of the external carotid artery (diameter reversal) on conventional carotid ultrasonography. We then measured the internal diameter of the extracranial distal ICA by transoral carotid ultrasonography. We compared the incidence of a "bottle neck" appearance, diameter reversal, and the ICA diameter between the 2 groups. RESULTS: The bottle neck and diameter reversal were shown in 14 (74%) and 16 (84%) of the 19 ICAs in the moyamoya group, respectively (chi2 test, P<.0001). However, neither of them was shown in the control group. The diameter of the distal ICA in the moyamoya group was significantly smaller than that in the control group (mean+/-SD, 2.4+/-0.60 versus 4.1+/-0.52 mm; unpaired t test, P<.0001). CONCLUSIONS: These results suggest that rapid internal diameter reduction at the proximal portion of the ICA, characterized by a bottle neck appearance or diameter reversal, is an important morphologic feature of moyamoya disease.

Adolescent↗
PubMed2006

[The questionnaire survey to clarify correspondence of medical doctors and dentists in Fukuoka City, Japan, for warfarin therapy at the dental extraction].

PURPOSE: The questionnaire survey was performed in order to clarify correspondence of medical doctors and dentists working at hospital service for warfarin therapy at the dental extraction. METHODS: For 17 senior dentists in 17 hospitals and 142 senior physicians in 82 hospitals in Fukuoka City, we investigated using the questionnaire whether they supported dental extraction under warfarin therapy or not in patients having warfarin treatment with past history of cardioembolic stroke due to non-valvular atrial fibrillation (NVAF). Specialty and experience of stroke after withdrawal of warfarin were also asked in medical doctors. RESULT: The reply was obtained from 14 dentists (82.4%) and 66 doctors (46.5%). The number of dentists and doctors who pull out a tooth under warfarin treatment continuation were 12 persons (85.7%) and 32 persons (48.5%), respectively. The rates in doctors whose specialty was stroke, cardiovascular disease, and others were 78.6% (11/14), 36.0% (9/25), and 44.4% (12/27), respectively. The rate in stroke specialists was significantly higher than that in cardiovascular disease specialists (p = 0.019). The stroke specialists had experience of stroke after withdrawal of warfarin more frequently than the cardiovascular disease specialists (57.1% vs. 20.0%, p = 0.033). CONCLUSION: The rates of acceptance in tooth extraction under warfarin treatment continuation of the dentist were high in Fukuoka city, while that of the medical doctors were not. Rate of doctor's acceptance differed according to the specialties, and may be affected by experience of stroke after cessation of warfarin therapy.

Anticoagulants↗
PubMed2005

Moderate atheroma of the aortic arch and the risk of stroke.

BACKGROUND AND PURPOSE: Severe atheroma >or=4 or 5 mm of the aortic arch is a risk factor for stroke. We investigated the most predictive characteristics of arch atheroma, including maximal plaque thickness, for subsequent cardiovascular events, and also examined whether moderate atheroma<4 mm is a risk of cerebral emboli. METHODS: The maximal plaque thickness (MPT) and plaque morphologies of the aortic arch were evaluated by transesophageal echocardiography in 236 patients with ischemic stroke. We assessed the relationship between the incidence of cardiovascular events, recurrent stroke or myocardial infarction, and the characteristics of the atheroma. We also investigated the thickness of atheroma in patients with known causes of stroke (n=148) and in patients with undetermined causes (n=19). RESULTS: Cardiovascular events occurred in 47 patients in the follow-up period with a mean of 3.5 years. MPT was a significant risk factor of the cardiovascular events, although plaque morphologies were not. For the receiver operator characteristics curve analysis, the suitable cutoff point of MPT associated with the cardiovascular events was 3.5 mm. Patients with MPT >or=3.5 mm had a higher risk of cardiovascular events than did those with MPT<3.5 mm. In addition, aortic atheroma with MPT >or=3.5 mm was more frequently observed in patients with undetermined causes of stroke than those with known causes at 68 vs. 39% (p=0.024). CONCLUSIONS: MPT >or=3.5 mm is the best predictor of subsequent cardiovascular events and a possible cause of embolic stroke.

Aged↗
PubMed2005

Optimal dose of prothrombin complex concentrate for acute reversal of oral anticoagulation.

We investigated optimal dose of prothrombin complex concentrate (PCC) for acute reversal of oral anticoagulation in patients with major hemorrhagic complications or who required invasive procedures. We also checked how rapidly international normalized ratio (INR) was reversed after PCC administration. INR was measured before and 10-60 min after administration of PCC with or without vitamin K in 42 patients (men 28, women 14, median age of 70 years old) who had received warfarin but required rapid reversal of INR because of a hemorrhagic complication or medical procedure. The amount of PCC administered was 200 IU in six patients, 500 IU in 30, 1000 IU in 3, and 1500 IU in the other 3. Additional administration of PCC was performed when the correction of INR was inadequate. In 10 of the 42 cases, INR was measured serially, before, 10 and 60 min and 12-24 h after the administration of PCC and vitamin K. In the six patients who received PCC of 200 IU, INR values of 3.34 median (range 2.06 to 5.08) decreased to 1.85 (range 1.23 to 2.43) significantly (Wilcoxon's rank sum test, p=0.028), but in three patients (50%), INR values were still above 2.0 after the administration. In 30 patients treated with PCC of 500 IU, values decreased from 2.49 median (range 1.54 to 10.00) to 1.19 (range 0.87 to 1.55) significantly (p<0.0001). The corrected INR values were below 1.5 in 25 of 26 patients (96%) who had initial INR values from 2.0 to 4.9. In four patients with initial INR of 5.0 or more, the reversed INR was below 1.5 in one (25%), between 1.5 and 2.0 in two (50%), and above 2.0 in one (25%) who had additional administration of 500 IU PCC lowering INR from 2.01 to 1.48. Values of INR in the six patients receiving 1000 IU or 1500 IU, INR decreased from 2.33 median (range 1.96 to 4.00) to 0.96 (range 0.87 to 1.24, p=0.028). In the 10 patients with serial measurement, INR changed from 2.67 median (range 2.05 to 10.00) to 1.17 (range 0.99 to 1.60) 10 min after the administration. The INR values remained stable 60 min and 12-24 h after the PCC administration. The 500 IU of PCC is likely to be optimal dose of PCC for emergent reversal of INR in patients requiring rapid correction of INR below 5.0, but to be inadequate dose in patients with INR of 5.0 or more. PCC administration with vitamin K may finish reversing INR rapidly within 10 min and keep the reversed INR values for 12-24 h.

Administration, Oral↗
PubMed2005

Is stroke a paradoxical embolism in patients with patent foramen ovale?

OBJECTIVE: Purpose was to assess the stroke mechanism in patients with patent foramen ovale (PFO). METHODS: We reviewed the medical records of 111 stroke patients with PFO and sinus rhythm (PFO-S group), 25 with PFO and atrial fibrillation (AF) (PFO-AF group) and 67 with AF but not PFO (AF group), who had received contrast transesophageal echocardiography. The clinical and neuroradiological findings were then compared among the three groups. Deep vein thrombosis was investigated in 93 patients with PFO. We determined the number of patients with definite paradoxical embolism who met three criteria: deep vein thrombosis, neuroradiological features indicating embolic stroke, and the absence of other sources of emboli. We also evaluated those with probable paradoxical embolism who met two of the three criteria. RESULTS: The PFO-S group more frequently exhibited hypercholesterolemia (p<0.0001) and lesions limited to the posterior circulation (p<0.0004), and less frequently exhibited large or cortical lesions in the anterior circulation (p=0.0008, p<0.0001, respectively), than the PFO-AF and AF groups. In the PFO-S and PFO-AF groups, other sources of emboli such as a cardiac source of emboli, cerebral artery stenosis > or =50%, or complicated atheroma in the aortic arch were identified in 72 cases (52.9%). In the 93 patients with examination for deep vein thrombosis, the definite and probable criteria of paradoxical embolism were fulfilled only in three (3.2%) and 33 cases (35.5%), respectively. CONCLUSION: In stroke patients with PFO, not only paradoxical brain embolism through the PFO but also other causes of stroke may contribute to the development of stroke.

Age of Onset↗
PubMed2005

Transoral carotid ultrasonography for evaluating internal carotid artery occlusion.

BACKGROUND AND PURPOSE: Transoral carotid ultrasonography (TOCU) has enabled the assessment of the distal portion of the extracranial internal carotid artery (ICA). We evaluated the ultrasonographic features of ICA occlusion using TOCU. METHODS: We studied 50 occluded ICAs in 42 stroke patients. The mechanism of ICA occlusion was embolic (group E) in 14 arteries and thrombotic (group T) in the other 36 arteries. We used a color flow imaging system equipped with special convex array transducers, and placed the probe on the postero-lateral pharyngeal wall to identify the distal extracranial ICA. We evaluated intraluminal echodensity (lucent or opaque) and measured the diameter of the ICA. Then, we examined the relationship of these early (<1 week after onset) and chronic (>4 weeks after onset) phase TOCU findings to the mechanism of ICA occlusion and the site of occlusion. RESULTS: In the early phase of a stroke, the intraluminal echodensity was more frequently lucent (9/11, 81.8%) in group E than in group T (5/20, 20%, p<0.05). In the chronic phase, echodensity became opaque in both groups. In the early phase, the lucent echodensity was more frequently seen in patients with distal occlusion than in those with proximal occlusion. Thus, it may represent blood or fresh thrombus formation. In patients with unilateral ICA occlusion, the occluded ICA was significantly smaller in diameter than the non-occluded contralateral artery both in the early and chronic phases. CONCLUSION: The echodensity and diameter of the extracranial ICA distal portion as found on TOCU can help to identify the mechanism of ICA occlusion.

Aged↗
PubMed2005

Right-to-left shunt evaluated at the aortic arch by contrast-enhanced transesophageal echocardiography.

OBJECTIVE: The right-to-left shunt (RLS) is diagnosed by contrast-enhanced transesophageal echocardiographic monitoring of the bilateral atria (cTEE-BA). However, the procedure is often disturbed by nonsmoke spontaneous individual contrast (NSSIC) with fast motion, which appears in the left atrium after respiratory maneuvers without administration of a contrast medium and moves past in several seconds. We attempted to perform cTEE monitoring of the aortic arch (cTEE-AA) for evaluation of the RLS and compared the findings with those of cTEE-BA. METHODS: Both cTEE-BA and cTEE-AA were performed in 168 patients with ischemic stroke (133 men and 35 women; mean age +/- SD, 62.0 +/- 14.4 years). The frequency of NSSIC in the left atrium was compared with that in the aortic arch during the respiratory maneuver. When contrast much brighter than the NSSIC was visualized in the left atrium and the aortic arch during the respiratory maneuver with administration of the contrast medium, we considered the RLS to be positive in the cTEE-BA and cTEE-AA, respectively. Findings were then compared between the 2 examinations. RESULTS: Nonsmoke spontaneous individual contrast was more frequently observed in the left atrium than the aortic arch (61.3% versus 14.9%; chi2 test, P < .0001). The RLS was positive in 34 patients in the cTEE-BA and in 39 patients in the cTEE-AA. The sensitivity and specificity of the cTEE-AA for the cTEE-BA were 100% and 96.3%, respectively. CONCLUSIONS: The cTEE-AA may be an alternative method for detection of an RLS, especially in patients with a large amount of NSSIC in the left atrium.

Aorta, Thoracic↗
PubMed2005

Atherosclerosis found on carotid ultrasonography is associated with atherosclerosis on coronary intravascular ultrasonography.

OBJECTIVE: Little has been reported on the relationship between left main coronary artery atherosclerosis and carotid ultrasonographic results. We evaluated the association between carotid and coronary atherosclerosis assessed by coronary intravascular ultrasonography (IVUS) in 45 patients. METHODS: We counted the number of plaques with intima-media thickness (IMT) greater than or equal to 1.1 mm and calculated a plaque score by summing all plaque thicknesses. With the use of IVUS, the percent plaque area was calculated at the proximal, middle, and distal sites of the left main coronary artery. The maximum percent plaque area and mean percent plaque area of the 3 sites were also calculated. Relationships among the degree of left main coronary artery atherosclerosis and carotid atherosclerosis and vascular risk factors were evaluated. RESULTS: The mean percent plaque area and maximum percent plaque area were increased in men and in patients with hypertension compared with women and those without hypertension (P < .1). Both the average of the maximum common carotid IMT and plaque number were correlated with both the mean percent plaque area and maximum percent plaque area (P < .05). Men, the presence of hypertension, and the average of the maximum common carotid IMT were correlated with both the mean percent plaque area and maximum percent plaque area by multiple linear regression analysis (P < .05). CONCLUSIONS: The average of the maximum common carotid IMT was significantly correlated with left main coronary artery atherosclerosis evaluated by IVUS.

Arteriosclerosis↗
PubMed2005

[A case of acute cervical epidural hematoma mimicking medial medullary infarction complicated by arterial dissection].

A 67-year woman with hypertension rapidly noted weakness of the right upper and lower extremities with posterior cervical pain. At admission to our hospital, she showed right hemiparesis without facial palsy, and bilateral pathological reflex. Chest X-ray demonstrated enlargement of the mediastinal shadow. We suspected that she developed aortic arch dissection extending into the vertebral arteries and subsequent medial medullary infarction. However, enhanced thoracic CT, brain MRI-DWI and MRA examinations were negative. Her symptoms rapidly recovered three hours after the onset. A cervical MRI study revealed cervical epidural hematoma locating between the C3 and C6, which suppressed right side of the spinal cord. In conclusion, cervical epidural hematoma as well as medial medullary infarction complicated by the vertebral arterial dissection should be urgently explored when a patient had a sudden onset of cervical pain and hemiparesis without facial palsy.

Aged↗
PubMed2005

[Stroke in young adults in Japan].

The details of stroke in young adults remain unknown in Japan. We performed a multicenter survey to establish a stroke data bank for young adults in Japan. We collected clinical data of 7,245 acute stroke patients admitted to 18 hospitals in Japan. In patients admitted within the first 7 days of stroke, patients aged = < 50, = < 45, and = < 40 accounted for 8.9%, 4.2%, and 2.2%, respectively. Hypertension, diabetes mellitus, hypercholesterolemia, and non-valvular atrial fibrillation were significantly more frequent in the non-young than in the young, but smoking habits and patent foramen ovale were more frequent in the young than in the non-young. Brain infarction was the most predominant stroke subtype in the non-young, but not so in the young (62.6% vs. 36.7%, p < 0.01). Brain hemorrhage (20.8% vs. 32.1%, p < 0.01) and subarachnoid hemorrhage (7.3% vs. 26.1%, p < 0.01) were more frequent in the young. Causes of brain infarction and hemorrhage were often atypical in the young (2.8% vs. 25.1%, p < 0.001 and 4.6% vs. 20.2%, p < 0.0001, respectively). Causes of stroke in the young was often atypical, such as cerebral arterial dissection, Moyamoya disease, antiphospholipid syndrome, arteriovenous malformation, et al. Because causes and underlying risk factors of stroke in young adults were quite different from those in older patients, we need to establish the data bank and to explore optimal measures of the diagnosis and management for young stroke patients.

Adolescent↗
PubMed2004

Aortic arch atherosclerotic lesions and the recurrence of ischemic stroke.

BACKGROUND AND PURPOSE: Aortic arch atherosclerotic lesions are often associated with embolic brain infarction. We investigated the relationship between stroke recurrence and the characteristics of aortic arch atherosclerotic lesions. METHODS: Among 487 stroke patients who underwent transesophageal echocardiography, 283 patients with brain embolism diagnosed without significant occlusive lesions (> or =50%) in their cerebral arteries were included in this study. We measured the intima-media thickness (IMT) and evaluated the extension and mobility of the aortic arch atherosclerotic lesions. During a mean follow-up period of 3.4 years, we investigated the relationship between stroke recurrence and the various characteristics of the aortic arch atherosclerotic lesions. RESULTS: An IMT > or =4.0 mm was found in 67 patients (25.3%). In 51 of these patients, the aortic lesions extended to the origin of the branches of the arch. Recurrences of cerebral ischemic events were found in 32 patients (recurrence group) and not in the other 251 (nonrecurrence group). Aortic atheroma > or =4.0 mm (41% versus 22%), aortic atheroma extending to the branches (63% versus 39%), and both (38% versus 16%) were more frequently seen in the recurrence group than in the nonrecurrence group (P<0.05, P<0.1, P<0.01, respectively). After adjustment for age and the presence of hypertension, an aortic atheroma that was > or =4.0 mm as well as extending to the branches was found to be an independent predictor of ischemic stroke recurrence (hazard ratio=2.42, P<0.05). CONCLUSIONS: Stroke recurrence is associated with the severity of the atheroma (IMT > or =4.0 mm) and plaque extension to the branches.

Aged↗