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Biomedical subjects

S Miyajima

Publications and source records attributed to S Miyajima.

71 records · Page 4Linked to original sources
PubMed1988

Danger of use of disopyramide in patients with hypertrophic obstructive cardiomyopathy. An electrophysiologic study.

A 61-year-old man with hypertrophic obstructive cardiomyopathy with asymptomatic ventricular tachycardia underwent electrophysiologic study. Double extrastimuli at the right ventricular outflow tract induced polymorphic ventricular tachycardia which degenerated into fibrillation. After intravenous administration of 50 mg of disopyramide, the pressure gradient in the outflow tract disappeared, but the tachycardia inducing zone appeared at the right ventricular apex. Although disopyramide may be used in patients with hypertrophic cardiomyopathy to relieve the intraventricular pressure gradient, it should be used only after evaluating its safety and efficacy electrophysiologically.

Cardiac Pacing, Artificial↗
PubMed1988

[Evaluation of therapeutic interventions of sustained monomorphic ventricular tachycardia guided by an electrophysiologic study: a case report].

Therapeutic evaluation of sustained monomorphic ventricular tachycardia (VT) using electrophysiologic study (EPS) is presented in a case of refractory VT. A 54-year-old man with a history of recurring syncope underwent coronary angiography which revealed total occlusion of the posterior descending branch of the right coronary artery. Left ventriculography showed a left ventricular aneurysm at the cardiac apex. Ejection fraction of the left ventricle was 36%. He had four VTs of different QRS morphologies in 12 lead electrocardiograms. According to our programmed ventricular stimulations, single or double, and rarely triple, extra stimuli were administered after eight basic stimuli at two basic cycle lengths. Rapid ventricular pacing, up to 210 bpm, was then added. The stimuli were delivered to two different sites in the right ventricle and to at least one site in the left ventricle. When the entire protocol could not induce VT, isoproterenol was given intravenously, and the same protocol was repeated. No drug could prevent VT attacks, even after the surgical resection of two VT foci, VT was still inducible. Postoperative drug therapy could not prevent VT induction in EPS. However, changes in the mode required for VT induction were observed. Among 47 patients with sustained monomorphic VT treated in our hospital, 24 had EPS to evaluate the efficacies of therapeutic interventions, such as drugs and surgery. In 14 patients, no VT was induced by the entire VT induction protocol. Among the remaining 10 patients, four showed changes in the VT induction mode, but VT recurred in their clinical courses even after their treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1987

Early experiences of endocardial catheter mapping of the left ventricle in patients with sustained ventricular tachycardia--efficacy, safety and complications.

In 23 patients with recurrent sustained ventricular tachycardia (VT) which originated from the left ventricle, endocardial catheter mapping has performed. In an additional 14 patients we also stimulated their left ventricle for non-sustained VT. Multiple sites could be mapped for the recording of local electrical activity, for pacing and for the induction of VT. These procedures could be done without complication. A careful, reasonable, and safe method of endocardial mapping will facilitate clinical electrophysiologic study.

Adult↗
PubMed1987

Potency and receptors involved in coronary vasoconstriction caused by neuropeptide Y(NPY).

Using anesthetized dogs, the coronary vascular effects of neuropeptide Y (NPY) were studied and the action of alpha- or serotonergic receptor blockade on the action of NPY was evaluated. To demonstrate the biological significance of the action of NPY, the vasoconstrictor potencies of NPY and norepinephrine were compared. One to 5 nmol of intracoronary NPY reduced coronary flow in a dose-dependent manner. The action started rather gradually and lasted for 10 min or more. Since perfusion pressure and central venous pressure were unchanged, the decrease in coronary flow should be a result of coronary vasoconstriction. Intracoronary norepinephrine infusion caused vasodilatation but when dogs were pretreated with 0.5 to 1.0 mg/kg of systemic propranolol, a vasoconstrictor effect was observed at a 5 times higher dose than with NPY. Furthermore, the action of NE was only transient, lasting for 30 sec or less. The vasoconstrictor action of NPY was not antagonized by phentolamine or by ketanserin. Since NPY is an endogenous polypeptide found in the sympathetic nerve terminals around coronary arteries, it may participate in the regulation of coronary flow.

Animals↗