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M Yasaka

Publications and source records attributed to M Yasaka.

At least 55 records · Page 3Linked to original sources
PubMed1993

Mobile string-like thrombus on the calcified aortic valve in cardioembolic stroke--a case report.

The calcified aortic valve has been associated with being a possible source of emboli in cardioembolic stroke. However, thrombus on the calcified aortic valve has not been identified with two-dimensional echocardiography. A seventy-two-year-old woman with calcified aortic stenosis was admitted with brain embolism. She had not previously received any platelet antiaggregant or anticoagulant. At admission, two-dimensional echocardiography demonstrated a mobile string-like abnormal echo attached to the calcified aortic valve, which showed regression and enlargement repeatedly during admission. No symptoms or clinical data suggested infective endocarditis or nonbacterial thrombotic endocarditis. After commencement of antiplatelet therapy, the abnormal echo regressed and disappeared. She continued to take the medication for seven months and then discontinued. Three months later, she developed recurrence of stroke, and an abnormal echo on the calcified aortic valve was again detected by two-dimensional echocardiography. The authors believe that the abnormal echo on the calcified aortic valve was thrombus and that it was the embolic source. Calcified aortic valve may thus be a causative lesion for mobile string-like thrombus. Two-dimensional echocardiography should be performed repeatedly in patients with calcified aortic valve and brain embolism.

Aged↗
PubMed1993

[Warfarin therapy for secondary prevention of cardioembolic stroke with nonvalvular atrial fibrillation--a retrospective study].

In order to evaluate the efficacy of warfarin for the secondary prevention of cardioembolic stroke due to nonvalvular atrial fibrillation (NVAF), we retrospectively investigated the frequencies of recurrent brain embolism and hemorrhagic complications in 68 subjects (62 +/- 9 years old, 54 men and 14 women), who had experienced at least one cardioembolic stroke prior to the study period. The follow-up period was 39 +/- 27 months. Paroxysmal and persistent atrial fibrillation were seen in 37 and 31 subjects, respectively. We assigned the subjects to three subgroups according to types of the events during the follow-up; recurrence group, hemorrhage group, and non-accident group. Prothrombin time (international normalized ratio, INR) was assessed as mean value during the follow-up period. The prothrombin time at the time of recurrence and hemorrhagic complication was also taken into consideration for data analysis. Recurrent brain embolism was observed in three patients (1.4%/yr). Major bleeding occurred in 12 patients (5.5%/yr) and three of them were fatal (subarachnoid hemorrhage, brain hemorrhage, and acute subdural hematoma). The mean value of INR in the hemorrhage group (3.0) was higher than that in the recurrence group (2.2) and in the non-accident group (2.3) (p < 0.001, vs. non-accident group). The lowest mean value of INR in the hemorrhage group was 2.5. The prothrombin time in the recurrence group did not differ from that in the non-accident group. The death rate in the hemorrhage group (4/12, 33.3%) was higher than those in the recurrence group (0) and in the non-accident group (4/53, 7.5%) (p < 0.01, vs. non-accident group).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Hypercoagulability in the left atrium: Part II: Coagulation factors.

The relationship between a hypercoagulable state and intracardiac thrombus formation is reviewed, with reference to the pathophysiology of intracardiac thrombus in patients with acute cardioembolic stroke, and those with mitral stenosis. When the development or enlargement of intracardiac thrombus is followed serially by echocardiography, the diameter of the inferior vena cava is seen to decrease as the hematocrit increases, particularly in patients with negative water balance taking diuretics. These findings strongly suggest that dehydration could play an important role in the formation of thrombus. A hypercoagulable and secondarily enhanced fibrinolytic state exists in the cardiac chamber of patients with acute cardioembolic stroke or with intracardiac thrombus. This can be evaluated by plasma levels of fibrinopeptide A, fibrinopeptide B beta 15-42, thrombin-antithrombin III complex and D-dimer. Anticoagulant treatment suppresses thrombin activity in the cardiac chamber, allowing plasma fibrinolytic activity to predominate and reduce the size of the intracardiac thrombus.

Atrial Fibrillation↗
PubMed1993

[Heart diseases].

Explore the source record for details and available documents.

Cerebrovascular Disorders↗
PubMed1992

Ultrasonic evaluation of the site of carotid axis occlusion in patients with acute cardioembolic stroke.

PURPOSE: We performed the present study to determine whether the site of cardioembolic occlusion in the carotid axis could be identified by end-diastolic velocity measurements of the common carotid arteries. SUMMARY OF REPORT: Using duplex carotid ultrasonography, we measured the flow velocity in the common carotid arteries and calculated the side-to-side ratios of the end-diastolic velocity (ED ratio; the end-diastolic velocity of the nonaffected side divided by that of the affected side) in 46 patients with acute cardioembolic stroke. The velocity on the faster side was divided by the slower velocity to obtain the normal values of ED ratio in 30 controls. The ED ratios were compared with the angiographic findings, in which unilateral intracranial internal carotid artery occlusion was present in 20 patients (IC group), occlusion of the horizontal segment of the middle cerebral artery was present in 16 patients (M1 group), and branch occlusion of the middle cerebral artery was present in 10 patients (MBr group). The ED ratios of the control group were less than 1.3; those of the MBr group generally less than 1.3; the IC group greater than 4.0, except in two patients with severe cerebral edema; and those of the M1 group between 1.3 and 4.0. Therefore, the IC group was easily distinguished from the other groups by an ED ratio greater than or equal to 4.0, with an accuracy of 97%, and the M1 group by an ED ratio greater than or equal to 1.3 and less than 4.0, with an accuracy of 93%. CONCLUSIONS: We found the ED ratio useful to identify internal carotid artery and middle cerebral artery occlusion in patients with cardioembolic stroke unless severe cerebral edema was present.

Arterial Occlusive Diseases↗
PubMed1992

Aortogenic embolic stroke: a transesophageal echocardiographic approach.

BACKGROUND AND PURPOSE: We studied the frequency and grade of atherosclerotic changes in the thoracic aorta and their significance as embologenic lesions in patients with stroke. METHODS: Using transesophageal echocardiography, we evaluated complicated lesions in the thoracic aortas of 62 patients who met our clinical criteria for embolic stroke. A complicated lesion was defined as a raised lesion with an irregular surface or acoustic shadow based on a comparative study of echocardiographic and histopathologic findings. The results were compared with plain radiographic findings and in some cases with computed tomographic or aortographic findings. RESULTS: Twenty-six patients (42%) showed complicated aortic arch lesions on echocardiogram. Transesophageal echocardiography brought us more abundant information than other techniques. Aortic knob calcification by plain radiography correlated well with the presence of echocardiographically complicated lesions, suggesting its utility for rough screening of atherosclerotic changes. Fifty-two patients had other potential embolic sources in the heart or cervical arteries. Among the remaining 10 patients without extra-aortic embolic sources, three showed complicated lesions and were diagnosed as having aortogenic embolic stroke. CONCLUSIONS: Aortic atherosclerosis should be recognized as an embolic source of stroke and the advantage of transesophageal echocardiography recognized in its evaluation.

Adult↗
PubMed1992

Immediate anticoagulation for intracardiac thrombus in acute cardioembolic stroke.

To assess the efficacy of immediate anticoagulation therapy on intracardiac thrombus formation in acute cardioembolic stroke, serial two-dimensional echocardiographic examinations were performed in 25 patients with acute cardioembolic stroke. Anticoagulation therapy was commenced within two days of onset in 7 patients (group A) but not in 18 patients (group B). Appearance or enlargement of intracardiac thrombi were not detected in group A but were noted in 7 patients (39%) of group B. Recurrence of systemic embolism was demonstrated in 3 patients (17%) of group B. There were no serious hemorrhagic complications in either group. Immediate anticoagulation could, therefore, be effective in preventing intracardiac thrombus formation and the consequent recurrence of systemic embolization in acute cardioembolic stroke. Because the study was preliminary and not randomized, further randomized study is desirable to establish the efficacy of immediate anticoagulation therapy.

Cerebrovascular Disorders↗
PubMed1991

Intracardiac mobile thrombus and D-dimer fragment of fibrin in patients with mitral stenosis.

OBJECTIVE: To investigate the relation between intracardiac thrombus and blood coagulability in patients with mitral stenosis. DESIGN: Prospective study. Cross sectional echocardiography and plasma concentrations of the D-dimer fragment of fibrin were used concurrently to detect intracardiac thrombus in patients with mitral stenosis. SETTING: Department of Medicine, National Cardiovascular Centre, Osaka, Japan. PATIENTS: 63 patients with mitral stenosis. None of them had been receiving any anticoagulants or antiplatelet agents. MAIN OUTCOME MEASURES: Plasma concentrations of D-dimer in patients with a mobile intracardiac thrombus, those in patients with a non-mobile intracardiac thrombus, and those in patients without an intracardiac thrombus. RESULTS: A mobile intracardiac thrombus was found in 10 patients and a non-mobile thrombus in eight. The remaining 45 patients had no intracardiac thrombi. Plasma concentrations of D-dimer in the 10 patients with a mobile thrombus were all greater than 300 ng/ml (mean 983.3, 95% confidence interval 498.9 to 1467.7 ng/ml) and they were significantly higher than those in the patients with a non-mobile thrombus (226.2, 33.6 to 418.8 ng/ml) and the patients without an intracardiac thrombus (147.2, 110.4 to 184 ng/ml). CONCLUSIONS: A high plasma concentration of D-dimer seemed to reflect a hypercoagulable intracardiac state and may be a helpful indicator of the possible presence of mobile intracardiac thrombus in patients with mitral stenosis.

Antifibrinolytic Agents↗
PubMed1991

Cardioembolic stroke revealed by increased hemostatic markers associated with intracardiac thrombus.

BACKGROUND AND PURPOSE: The presence of hemocoagulative disorders in acute ischemic stroke has been reported occasionally. However, the cause of the hemostatic derangement has not been fully elucidated. CASE DESCRIPTION: A 66-year-old woman with a history of hypertension and myocardial infarction developed pure motor hemiparesis. On admission, she was thought to have a lacunar infarction. However, computed tomography of the brain with contrast medium revealed a small infarct in the cortex of the frontal lobe. Conventional angiography showed no stenotic or occlusive lesions. Sensitive hemocoagulative tests revealed hypercoagulative and hyperfibrinolytic states. Ultrafast computed tomography of the heart with contrast enhancement demonstrated a large left ventricular mural thrombus. There were no further abnormal findings suggestive of other systemic diseases that affect blood coagulability. As a result, the patient was diagnosed as having suffered a cardioembolic stroke. CONCLUSIONS: An intracardiac thrombus could be one of the causes of the hemostatic disorders of acute cardioembolic stroke.

Aged↗
PubMed1991

[Hemodynamics of the vertebral artery in subclavian steal syndrome and subclavian steal phenomenon].

To evaluate hemodynamics of the vertebral artery (VA) in subclavian steal syndrome (SSS) and subclavian steal phenomenon (SSP), blood flow velocities of the bilateral VAs were measured by duplex ultrasonography in four patients with SSS and eight patients with SSP. The reversal of flow in the VA was noted in both systolic and diastolic phases in all of the SSS group, and was recorded only in a systolic phase in all but one of the SSP group. The antegrade mean flow velocities in the VA on the unaffected side in the SSS group were significantly higher than those in the SSP group. This indicates that collateral blood flow through the VA in the SSS group is still insufficient to compensate the blood requirement of the upper extremity on the affected side. In conclusion, hemodynamics of the VA in the SSS group could be distinguished from those in the SSP group by duplex ultrasonography.

Adult↗
PubMed1991

[A case of central pontine and extra-pontine myelinolysis demonstrated by magnetic resonance imaging].

A 74-year-old woman was admitted because of disturbed consciousness due to iatrogenic hyponatremia. At admission, her serum level of sodium was 88 mEq/l. The hyponatremia was carefully corrected with physiologic saline for three days at a rate of 0.75 mEq/h until the serum sodium concentration of 135 mEq/l was achieved. Her neurologic state gradually improved to respond to painful stimuli with her left hand during the first week of treatment, but further improvement was not noted after that. On the 16th hospital day, seizure developed on her face and left upper extremity. Although abnormal lesions were not detected by MRI of the brain at admission, those performed on the 15th hospital day revealed multiple uncommon lesions with Tl and Gd enhanced images. On Tl images areas of low signal intensity were found in the central pons and left putamen, which were more clearly demonstrated by Gd enhanced MRI images. These lesions were considered to be consistent with central pontine and extra-pontine myelinolysis (CPEM). In addition, a part of the right temporal cortex was enhanced clearly by Gd-DTPA, which was also thought to be an extra-pontine myelinolysis. These lesions were responsible for the development of neurological signs due to CPEM. To our knowledge, this is the first case in which a lesion in the cerebral cortex was revealed as an extra-pontine myelinolysis by Gd enhanced MRI images. Gd enhanced MRI is useful for detecting the extra-pontine myelinolysis as well as central pontine myelinolysis.

Aged↗
PubMed1991

[Neuroradiological analysis of small infarcts in deep subcortical structure detected by CT].

We studied angiographic findings of 56 patients who were diagnosed as lacunar infarcts in the basal ganglia or deep subcortical white matter based on clinical symptomatology and brain computed tomography. In 26 patients with CT lesions less than 15 mm in diameter, only eight (31%) showed minor angiographic findings. In 30 patients with lesion of 15 mm or more, however, 22 (73%) had abnormal angiographic findings. Fourteen of the 22 patients had minor irregularities, three had 25-75% stenosis, five had 75% less than stenosis at the bifurcation of the common carotid artery or the horizontal portion of the middle cerebral artery. Our findings support the notion that a small lesion on CT can result from an occlusion of the perforating artery itself and a larger lesion is much related to the major vessel or heart diseases, i.e., emboli from the parent artery or heart, obstruction of perforators at their origin by an atheromatous plaque of the horizontal portion of the middle cerebral artery, or terminal zone infarct due to hemodynamically significant stenotic lesion. In patients with a larger deep infarct on CT, further investigation of the arteries in the carotid-axis and heart is important for determination of therapeutic indication.

Aged↗
PubMed1990

Regression of intracardiac thrombus after embolic stroke.

Using two-dimensional echocardiography, we studied the pathophysiology of intracardiac thrombus regression accompanied by anticoagulant therapy in 82 consecutive patients with acute cardiogenic cerebral embolism. We noted intracardiac thrombus in 15 patients; nine of the 15 were started on anticoagulant therapy with warfarin potassium to maintain the prothrombin time between 2.5 and 3.5 (international normalized ratio). Serial two-dimensional echocardiograms were obtained for these nine patients before and after anticoagulation, with the plasma levels of fibrinopeptide A, fibrinopeptide B beta 15-42, and D-dimer measured at the same time. In eight of the nine patients the intracardiac thrombi gradually decreased in size while the plasma level of fibrinopeptide A fell to within the normal range and the plasma levels of fibrinopeptide B beta 15-42 and D-dimer remained above the normal ranges. In the other patient the thrombus disappeared, with embolization to the right arm immediately after starting anticoagulant therapy. Mobile or small thrombi regressed earlier than nonmobile or large ones. We conclude that regression of intracardiac thrombi after anticoagulation may be based on the relative predominance of plasma fibrinolytic activity over anticoagulation-inhibited thrombin activity.

Aged↗
PubMed1990

Predisposing factors of recurrent embolization in cardiogenic cerebral embolism.

To elucidate the pathophysiology of intracardiac thrombus formation, serial two-dimensional echocardiographic examinations were performed on 30 consecutive patients with acute cardiogenic cerebral embolism in parallel with measurement of hematocrit and plasma levels of antithrombin III. The data from groups of patients with and without newly formed or enlarged thrombi were compared. Intracardiac thrombi were detected in eight of the 30 patients (27%), four at admission and four after admission. Enlargement of the thrombus was observed in four, and systemic embolization recurred in three of the eight. Antithrombin III levels already were low at admission in patients who later developed thrombi or had enlarged thrombi on serial examinations. When the development or enlargement of an intracardiac thrombus was detected by echocardiography, the diameter of the inferior vena cava was found to be reduced. At the same time, a decrease in antithrombin III and an increase in hematocrit were demonstrated. Intracardiac thrombi are frequently detected by repeated echocardiographic examination in patients with cerebral embolism. Dehydration seems to accelerate thrombus formation that is reflected by a decrease in antithrombin III. A low antithrombin III level at admission and/or a decrease in antithrombin III after admission may indicate the possible recurrence of embolism.

Antithrombin III↗
PubMedDate not supplied

Transcranial Doppler of a paradoxical brain embolism associated with a pulmonary arteriovenous fistula.

We herein report the case of a patient who had paradoxical brain embolism owing to a pulmonary arteriovenous fistula (PAVF) who was diagnosed as having a right-to-left shunt by transcranial Doppler (TCD) with saline contrast medium. TCD with saline contrast medium failed to detect any high-intensity transient signals immediately after catheter embolization of the PAVF. Thus, TCD with saline contrast medium was useful for identifying the presence of a right-to-left shunt and for confirming that the shunt had been obliterated after endovascular treatment.

Arteriovenous Fistula↗