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Biomedical subjects

Y Koiwaya

Publications and source records attributed to Y Koiwaya.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Left ventricular ejection fraction derived from resting 201Tl myocardial images].

To determine if resting 201Tl myocardial scintigraphy (rest-Tl) provides the information on left ventricular function, we compared preliminarily the parameters derived from rest-Tl with left ventricular ejection fraction (LVEF) derived from left ventriculography; while the parameters included Extent Score (ES), Severity Score (SS), Percent Uptake (PU), Area Index (AI). AI was derived from the averaging of [(A/B) x 100] in three or four central slices of short axis view on single photon emission computed tomography (A; area surrounded by inner edge of 201Tl myocardial image, B; area surrounded by outer edge of 201Tl myocardial image). The patients were comprised of 38 males and 16 females with a mean age of 53 years old (range 15-70) and classified into two groups; patients with myocardial infarction (n = 28, Group I), and patients with miscellaneous disease but without myocardial infarction (n = 26, Group II). In Group I, ES, SS and AI correlated with LVEF. If ES was less than 0.30, SS was less than 26.2, or AI was less than 19.8, LVEF was suggested more than 60% with an accuracy of 92%, 85% and 85%, respectively. In Group II, these did not correlate with LVEF. If there were area with PU less than 70% in the region perfused by left anterior descending artery or left circumflex artery, LVEF was less than 60% with an accuracy of 78%. In conclusion, rest-Tl images provide some informations on left ventricular function in some patients.

Adolescent↗
PubMed1989

Pacing failure due to markedly increased stimulation threshold 2 years after implantation: successful management with oral prednisolone: a case report.

In a 53-year-old male who had undergone transvenous permanent pacing, intracardiac potential reduced progressively over a 2-year period and exit block developed, while the stimulation threshold was markedly increased. After oral prednisolone for 5 months, the stimulation threshold reduced gradually along with an increase in intracardiac potential, culminating in no recurrence of exit block for the ensuing 2 years. The clinical course suggests that progressive reduction in intracardiac potential may have presaged the late development of exit block, and that oral prednisolone may be a therapeutic approach for the restoration of ventricular capture even 2 years after implantation.

Administration, Oral↗
PubMed1988

Aortic regurgitation secondary to diastolic prolapse of a tubular intimal flap into the left ventricle in a patient with anuloaortic ectasia.

A 32-year-old man with distal skeletal manifestations of Marfan's syndrome had experienced shortness of breath and orthopnea for one month. Physical examination showed the presence of severe aortic regurgitation. Both noninvasive and invasive studies revealed that the aortic regurgitation was induced by previously undescribed peculiar and unusual etiology: diastolic prolapse of a circumferentially dissected tubular intimal flap into the left ventricle. The patient underwent surgical repair with striking clinical improvement.

Adult↗
PubMed1988

Angiographic features in the infarct-related artery after intracoronary urokinase followed by prolonged anticoagulation. Role of ruptured atheromatous plaque and adherent thrombus in acute myocardial infarction in vivo.

To unravel sequential morphological features in infarct-related coronary arteries (IRCA), we performed coronary angiography (CAG) before, during, and immediately after intracoronary urokinase infusion in 43 consecutive patients. After 1 month of rigorous anticoagulation by intravenous heparin and subsequent oral warfarin or after the same period of treatment by antiplatelet agents, we repeated CAG in all patients except for one, who died 6 days after thrombolytic therapy. Thirty-two IRCAs were totally occluded, and 11 were severely occluded at baseline. With recanalization and/or reduction in luminal narrowing at the site of the occlusion by progressive removal of the overlying thrombus and plaque content, we recognized the development of extraluminal contrast pooling in an ellipsoid shape (type A), single or paired linear radiolucency(ies) with or without outpouching (type B), and definite outpouching (type C). The development of type A, B, and C lesions occurred in 4, 6, and 0 IRCAs immediately after thrombolytic therapy and in 0, 18, and 3 IRCAs 1 month later, respectively. Throughout the study, at least one of type A-C lesions developed in 23 of 43 (53.5%) IRCAs. Lesion development proceeded from total or severe occlusion to type A, then to type B or C, both accompanied by progressive reduction in luminal narrowing and frequent enlargement of outpouching. A postmortem study in one patient whose CAG immediately after thrombolytic therapy was interpreted as a type B lesion demonstrated a ruptured plaque with paired ridges. Serial observations in vivo indicate that many IRCAs are associated with a complex underlying spatial structure, probably composed of some part of ruptured atheromatous plaque with or without adherent thrombus. Recognition and identification of such complex structures beneath the accumulated thrombus are of great importance in both CAG interpretation and elucidation of the pathophysiological sequence of acute myocardial infarction in vivo and may enable prevention or more effective therapy of acute coronary events.

Aged↗
PubMed1987

A case of swallow syncope induced by vagotonic visceral reflex resulting in atrioventricular node suppression.

A 48-year-old man repeatedly experienced syncope associated with paroxysmal atrioventricular block (PAVB) while swallowing. PAVB ("Mobitz type II" AH block) occurred only when "balloon-like" deformity of the lower esophagus developed. Balloon inflation in the lower esophagus induced PAVB. However, inflation in the upper or mid portion, or other vagal maneuvers, caused only sinus slowing. PAVB was not induced after intravenous atropine. The PAVB in this patient was probably caused by a vagotonic reflex triggered by tensoreceptors in the lower esophagus, resulting in selective suppression of the atrioventricular node.

Deglutition↗
PubMed1987

Hyperventilation thallium-201 myocardial imaging for the diagnosis of vasospastic angina.

In seven patients with vasospastic angina, a transient myocardial perfusion defect was demonstrated on Tl-201 myocardial imaging after hyperventilation (HV). The development of spasm on one or more coronary arteries after HV was confirmed by later coronary arteriographic studies, with the perfusing area of the coronary arteries being compatible with the scintigraphic location of the defect. Repeated 12-lead electrocardiograms failed to establish the diagnosis in one of the seven patients. It is concluded that HV Tl-201 myocardial imaging provides invaluable information in establishing a diagnosis of vasospastic angina.

Adult↗
PubMed1986

Sinoatrial block induced by oral diltiazem.

A 58-year-old man with variant angina who had no history suggestive of sinus node dysfunction experienced palpitation with pulse deficit after 8 days of diltiazem treatment, 240 mg per day. Electrocardiogram (ECG) revealed frequent occurrence of sinoatrial block. After discontinuation of diltiazem, an ambulatory ECG demonstrated gradual reduction of the occurrence of sinoatrial block, and no recurrence 8 hours after the last dose of the drug. One should note that diltiazem induces not only sinus node suppression and atrioventricular conduction disturbance, but also sinoatrial block.

Administration, Oral↗
PubMed1986

Recurrent myocardial infarction and unexpected sudden death in a case of d-loop d-transposition of the great arteries associated with single coronary artery.

A 40-year-old man with d-loop d-transposition of the great arteries associated with single coronary artery type 3 by Hvass died unexpectedly. Postmortem study demonstrated myocardial infarction in the posterior portion of the right ventricle and interventricular septum, and complete obstruction of the proximal right coronary artery. The etiology of the unexpected death is discussed.

Adult↗
PubMed1986

Significance of collateral circulation on peri-infarct zone: assessment with stress thallium-201 scintigraphy.

To evaluate the significance of collateral circulation on peri-infarct zone, stress myocardial scintigraphy and contrast left ventriculography (LVG) were performed in 38 patients with recent myocardial infarction (MI). All patients had at least one completely occluded coronary artery corresponding to the infarct area. In patients with good collaterals, stress induced transient enlargement of the perfusion defect, however, in those with poor or no collaterals the enlargement did not occur (p less than 0.05). Wall motion abnormality on LVG was significantly milder in the former patients than in the latter (p less than 0.001). Transient enlargement of the perfusion defect after stress and milder left ventricular asynergy were more frequently observed in patients with anterior MI and good collaterals. These observations indicate that good collaterals may keep some myocardium in the peri-infarct zone viable.

Adult↗
PubMed1986

Increasing pre-excitation ("concertina effect") during vasospastic angina.

A patient with Wolff-Parkinson-White syndrome and variant angina developed progressive ST-segment elevation in the inferior leads after hyperventilation-induced right coronary artery spasm. At the same time, increasing pre-excitation ("concertina effect") developed with gradual prolongation of the AH interval on His bundle ECG. The ECG changes promptly disappeared after sublingual nitroglycerin, with termination of the chest pain. Transient ischemia induced by coronary artery spasm can be an etiology of increasing pre-excitation.

Angina Pectoris, Variant↗
PubMed1985

Ventricular tachycardia induced by clonidine withdrawal.

Ventricular tachycardia developed after the abrupt withdrawal of clonidine in a patient with atrial septal defect of the ostium secundum type, renal insufficiency, and hypertension. Ventricular tachycardia was completely suppressed by intravenous phentolamine, which contrasted with the limited effectiveness of intravenous lignocaine and procainamide. Sublingual glyceryl trinitrate or inhaled amyl nitrate reduced the blood pressure to a level similar to that after phentolamine but had no effect on the ventricular tachycardia. Ventricular tachycardia was probably produced by humoral or neural stimulation, or both, of upregulated myocardial alpha adrenoceptors.

Blood Pressure↗