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Biomedical subjects

T Motomiya

Publications and source records attributed to T Motomiya.

At least 37 records · Page 2Linked to original sources
PubMed1993

Factors for transient entrainment of ventricular tachycardias by rapid atrial pacing.

Thirteen patients with sustained ventricular tachycardia (VT) were studied to elucidate predisposing factors for the development of constant and progressive fusion by rapid atrial pacing. All patients demonstrated transient entrainment by rapid ventricular pacing during VT. Constant and progressive fusion were observed in 7 patients (positive group) during rapid atrial pacing, but not in 6 (negative group). In the positive group, VT was induced by atrial pacing in 2 patients. The demonstration of constant and progressive fusion by atrial pacing was not dependent on QRS morphology or ventriculoatrial conduction during VT. VT cycle length in the positive group (363 +/- 59 ms) was longer than in the negative group (297 +/- 31 ms; p = 0.033). The maximal atrial pacing rate producing 1:1 atrioventricular (AV) conduction in the positive group was 171 +/- 18 beats/min compared with 125 +/- 22 beats/min in the negative group (p = 0.002). There were distinct differences between the positive and negative groups in the ratio of VT cycle length to minimal atrial cycle length causing 1:1 AV conduction (1.02 +/- 0.12 vs 0.61 +/- 0.12; p = 0.0001). It is concluded that AV conduction, VT cycle length and especially their ratio are important factors for the development of transient entrainment by rapid atrial pacing during VT. Therefore, atrial pacing can be used as an easy and useful method to examine transient entrainment during VT.

Adult↗
PubMed1992

Double ventricular responses to a single atrial depolarization in a patient with dual AV nodal pathways.

Electrophysiological study was performed in a patient with atrioventricular nodal reentrant tachycardia (AVNRT). Double ventricular responses through dual AV nodal pathways were observed by atrial extrastimulus technique followed by initiation of AVNRT. The difference in conduction time between the slow and fast AV nodal pathways was longer than 320 msec. A ventricular extrastimulus delivered during sinus rhythm, which was not followed by ventriculoatrial conduction, also induced AVNRT. These findings indicated the presence of an antegrade critical delay and retrograde block in the slow AV nodal pathway, criteria necessary for the occurrence of a double ventricular response.

Adult↗
PubMed1992

Effect of thrombocytopenia on the onset of immune complex glomerulonephritis.

The effect of platelets on the development of immune complex glomerulonephritis (GN) was examined using bovine serum albumin (BSA) GN with platelet depletion. To clarify the role of platelets in the initial stage of BSA GN, thrombocytopenia was induced before BSA infusion. In 18 New Zealand white rabbits, BSA was intravenously injected twice after the presensitization. Eight of these BSA GN rabbits were injected daily with goat anti-rabbit platelet antiserum to induce thrombocytopenia, and platelet counts were maintained below 5 x 10(4)/microliters throughout the experiment. In the thrombocytopenic group, the degree of proteinuria was significantly decreased compared to the control group. Glomerular polymorphonuclear leukocyte infiltration, mononuclear cell proliferation, exudation and glomerular enlargement were significantly suppressed in the thrombocytopenic group. The results suggest that platelets may be quite important in the initiation and development of immune complex GN.

Animals↗
PubMed1991

Efficacy of disopyramide and mexiletine used alone or in combination in the treatment of ventricular premature beats.

The efficacy of oral disopyramide and mexiletine used alone or in combination was studied in 75 patients with frequent ventricular premature beats (VPBs). The efficacy was evaluated with 24-hour ambulatory ECG and greater than or equal to 75% reduction in the number of VPBs was defined as effective. When disopyramide or mexiletine were ineffective or not tolerated, the alternative drug was administered and the efficacy was again evaluated. If the single administration of neither drug was effective, the combination of disopyramide and mexiletine was then given. Either disopyramide or mexiletine was effective in 48 patients, and neither drug was effective in 19 patients. In 19 patients unresponsive to both drugs, combination therapy was effective in six patients (32%). Both drugs caused side effects or one drug caused side effects and another drug was ineffective in eight patients. In five out of those patients, we attempted combined therapy with a reduced dosage of those drugs that caused side effects. This therapy was effective in two patients without intolerable side effects. Thus, when the single use of neither disopyramide nor mexiletine single-drug therapy is effective, it is worthwhile to try combination therapy. Also, combination therapy with a reduced dosage of the drugs that caused side effects might be the therapy of choice in patients who have developed dose-dependent side effects.

Adult↗
PubMed1991

Association of humps on monophasic action potentials and ST-T alternans in a patient with Romano-Ward syndrome.

A case of Romano-Ward syndrome had episodes of torsade de pointes preceded by ST-T alternans. ST-T alternans was induced by isoproterenol and abolished by verapamil, lidocaine, mexiletine and MgSO4. A monophasic action potential (MAP) showed humps in MAPs at the right ventricular outflow tract but not at the right ventricular apex in alternate beats. Differences in the MAP duration were noted between the two areas and were associated with ST-T alternans. Atrial pacing abolished both humps and ST-T alternans. These results suggest that humps are a possible reflection of early afterdepolarizations and their appearance is limited to localized regions of the ventricles, which produces regional disparity of repolarization and ST-T alternans.

Action Potentials↗
PubMed1990

The role of electrophysiologic study for prediction and treatment of life-threatening arrhythmias.

The prognostic significance of drug therapy based on the electrophysiologic study (EPS) was examined during a mean follow-up period of 32 months in 45 patients with sustained ventricular tachycardia (SVT) and in 87 with nonsustained VT (NSVT), and in 7 survivors of cardiac arrest. The drug treatment during the follow-up period was divided into EPS-guided therapy and empirical therapy; in the former therapy, an effective drug for prevention of induced VT by EPS was given and in the latter therapy, an empirical drug was used because there was no effective drugs by EPS. Occurrence of SVT or sudden cardiac death was considered as an arrhythmic event. Of 45 patients with SVT, Group I consisted of 32 cases with organic heart disease (OHD) and Group II, 13 without OHD. In Group I, arrhythmic event occurred in only 2 of 15 patients with EPS-guided therapy, whereas 9 of 13 cases with empirical therapy had arrhythmic event (p less than 0.01). In Group II, no arrhythmic event was observed in the 9 patients with EPS-guided therapy, whereas it was seen in 3 of the 4 patients with empirical therapy (p less than 0.05). Of 87 patients with NSVT, 61 cases had OHD (Group III). SVT was induced by EPS in 13 patients in Group III. Arrhythmic event was not observed in 8 patients with EPS-guided therapy, whereas it was seen in 3 of the 5 patients with empirical therapy (p less than 0.05). Arrhythmic event occurred in 2 survivors of cardiac arrest who underwent empirical therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Effects of oral flecainide treatment of refractory tachyarrhythmias].

Oral flecainide treatment was given to five patients who were refractory to conventional antiarrhythmic agents. The five patients included one with atrioventricular reentrant tachycardia (AVRT), one with non-sustained ventricular tachycardia (nsVT) and three with sustained VT (sVT). Flecainide produced favorable responses in patients of AVRT, nsVT and sVT with arrhythmogenic right ventricular dysplasia (ARVD). In the case of AVRT, flecainide exhibited a preventive effect on tachycardia induced by programmed electrical stimulation (PES). In the case of nsVT, flecainide markedly reduced the number of VPC and abolished the VT on the Holter ECG. In the case of sVT with ARVD, sVT was not induced by PES after the flecainide. Long-term treatment with flecainide on these three cases produced complete prevention of tachycardias. As an adverse effect of flecainide, an aggravation of congestive heart failure was recognized in one case with cardiac sarcoidosis. PQ interval and QRS interval in all the cases were prolonged after flecainide. The results indicate that flecainide is a useful antiarrhythmic agent for tachyarrhythmias refractory to treatment with conventional drugs.

Administration, Oral↗
PubMed1989

Cardiomyopathy characterized by abnormal accumulation of desmin-type intermediate filaments in cardiac muscle fibers. A case report and review of the literature.

A 42-year-old Japanese male, who had been suffering from congestive heart failure and electrocardiographic abnormalities (A-V block, intraventricular conduction disturbance, ventricular tachycardia), died after a clinical course of 2 years and 1 month. Macroscopic investigation revealed dilation of the left ventricle and thickening of the right ventricular wall. The unique finding in this case was a circumferential fibrous scar in the median circular layer and outer oblique layer of the left ventricular wall. Biopsy and autopsy materials revealed diffuse loss of myofibrils in the central zone of cardiac muscle fibers, and replacement with aniline blue-positive homogeneous material (17-35% of the area of one muscle fiber). Electron microscopy revealed abnormal accumulation of fine filamentous material (7.5-25 nm in diameter), which was immunohistochemically proved to be desmin-type intermediate filament. Moreover, sarcoplasmic reticulum-like material was detected in the degenerated area. At autopsy, degeneration was detected all over the heart. The ventricular muscle fibers were more severely affected than the atrial muscle fibers. The conduction system was also affected, in some parts more severely than the surrounding ordinary muscle fibers. The pathogenesis of this disorder remains to be clarified.

Adult↗
PubMed1989

A clinicopathologic study of the accessory bypass tracts in six cases of Wolff-Parkinson-White syndrome.

A clinical and histologic correlation study was conducted to examine the accessory bypass tracts in 6 cases of Wolff-Parkinson-White syndrome. (1) Types A, B (Rosenbaum) and C (Ueda) were found in 2 cases each. From the polarity of the delta waves, the site of the bypass tract was assumed to be in the left posterior and left lateral free wall in type A, the right lateral and right posterior paraseptal regions in type B and in the right posterior paraseptal and right anterior paraseptal areas in type C. (2) In 6 cases 19 bypass tracts were found, consisting of 18 Kent bundles and 1 Mahaim fiber, from a total of 146,400 serial sections. The site of the bypass tract was the left lateral and left posterior walls in 2 type A cases, and the right lateral and right posterior walls in 2 type B cases, with good correspondence to our assumption. In both type C cases it was biventricular, composed of left posterior paraseptal and right lateral regions with an additional Mahaim fiber in 1 case. (3) A total of 46 cases of WPW syndrome were collected from the literature and the present paper; they consisted of 16 cases of type A, 20 of type B, 4 of type A + B and 6 of type C. Seventy % of type A cases showed a bypass tract in the left heart, and 64% of type B in the right heart. In 6 cases of type C, the bypass tract was found in various sites and in various combinations, requiring further investigation.

Adult↗
PubMed1989

[Lassa fever associated with effusive constrictive pericarditis and bilateral atrioventricular annular constriction: a case report].

A case of Lassa fever associated with effusive constrictive pericarditis and bilateral atrioventricular annular constriction was reported. A 49-year-old man, who had been diagnosed by indirect fluorescent antibody test as the first case of Lassa fever in Japan, was referred to the Hiroo Hospital because of syncope, progressive hepatomegaly, ascites and pericardial effusion in spite of pericardiocentesis and corticosteroid therapy. On admission, his blood pressure was 92/60 mmHg and he had a paradoxical pulse. Two-dimensional echocardiography revealed a localized pericardial effusion adjacent to the right ventricular wall and behind the left ventricular posterior wall. Bilateral atrioventricular annular constriction was also present. On pulsed Doppler echocardiography, the peak inflow velocities of the right and left ventricles increased during atrial systole. Right heart catheterization revealed a mean diastolic pressure gradient of 8 mmHg across the tricuspid valve. After pericardiectomy, a diastolic dip and plateau pattern became evident in the right ventricular pressure tracing, suggesting the presence of residual constriction. However, the atrioventricular annular constriction was no longer evident on two-dimensional echocardiography. This is considered the first reported case of subacute effusive constrictive pericarditis caused by Lassa fever.

Cardiac Catheterization↗
PubMed1988

Intracoronary urokinase in acute myocardial infarction: prevalence of total coronary occlusion during the early hours, effects on myocardial infarct size and left ventricular function, and outcome of residual coronary stenosis.

The effects of intracoronary thrombolysis (ICT) were studied in 88 acute myocardial infarction patients. Total coronary occlusion was observed in 67 of the 88 patients (76.1%) who were evaluated within 6 hours of the onset of symptoms. Among these 67 patients 42 (62.7%) were successfully recanalized by intracoronary urokinase. The recanalization rate was higher in the lesion at the left anterior descending artery, in younger patients (49 years or less) and in patients with a shorter history of pre-infarction angina. Eight of 11 patients (72.7%) with subtotal coronary occlusion and 17 of 35 patients (48.6%) with recanalization after ICT showed spontaneous regression of the residual coronary stenosis at the chronic stage angiography. There was no re-occlusion in the subtotal occlusion group and only 6 cases of re-occlusion (17.1%) in the recanalization group. The majority of re-occlusions progressed from the lesion with 99% residual stenosis and delayed filling. Accordingly the true value of additional percutaneous transluminal coronary angioplasty would be limited to the latter cases. Reduction in infarct size and improvement in left ventricular function were limited to those patients with incomplete or subtotal coronary occlusion and were not seen in cases with total obstruction which was recanalized by ICT.

Adult↗