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Biomedical subjects

H Fukuzaki

Publications and source records attributed to H Fukuzaki.

At least 271 records · Page 15Linked to original sources
PubMed1982

[Two-dimensional echocardiographic findings of patients with papillary muscle dysfunction].

Two-dimensional echocardiographic examination was performed to investigate pathophysiological mechanism of mitral regurgitation due to papillary muscle dysfunction in 6 patients with myocardial infarction (anterior : 3, inferior: 2 and subendocardial: 1) and 13 patients with dilated cardiomyopathy. The patients were divided into 2 groups; Group I was 9 with mitral valve prolapse and Group II was 10 without mitral valve prolapse (MVP). In Group I MVP was observed in the posterior leaflet in 6 and in both leaflets in the remainder. The apical four-chamber view of all patients in Group II showed that the point of mitral valve coaptation displaced toward the apex of the left ventricle during systole and the both mitral leaflets were convexed toward the left ventricle. Follow-up observation in a patient with dilated cardiomyopathy revealed that the heart was not enlarged (CTR 50%), no murmur was heard and mild anterior mitral leaflet prolapse was observed in 1979, but, in 1981, CTR became 63%, and a grade IV systolic murmur suggesting mitral regurgitation was noted. Two-dimensional echocardiography revealed that mitral leaflets became convex toward the left ventricle and coaptation point of the mitral closure shifted to the apex of the left ventricle below the level of mitral annulus. Thus, the transition to Group II from Group I was suggested. Echocardiographic measurements revealed that left ventricular end-diastolic dimension was 71 +/- 11 mm in Group I and 74 +/- 10 mm in Group II, left ventricular end-systolic dimension was 61 +/- 11 mm in Group I and 62 +/- 11 mm in Group II, and anterio-posterior mitral ring dimension was 31 +/- 3 mm in Group I and 35 +/- 3 mm in Group II (p less than 0.05). In conclusion, it was suggested that two mechanisms of mitral regurgitation are present in papillary muscle dysfunction; 1) mitral valve prolapse and 2) shift of mitral coaptation point toward the apex of the left ventricle associated with marked dilatation of the mitral annulus.

Adult↗
PubMed1982

[Comparison of exercise capacity with resting left ventricular function evaluated by various non-invasive methods in patients with old myocardial infarction].

The purpose of this study was to investigate the relationship between exercise capacity and resting left ventricular function assessed by several non-invasive methods in patients with old myocardial infarction. Subjects were 25 male patients whose endpoint was either dyspnea or general fatigue at the symptom-limited maximal graded treadmill exercise test according to Bruce protocol. The indices obtained by non-invasive cardiac examinations included left ventricular fractional shortening (% FS), scintigraphic infarct size (% SIS) by 201Tl myocardial scintigraphy and PEP/ET (so-called Weissler's index). A significant correlation of exercise duration with % FS (r = 0.67, p less than 0.001) or with % SIS (r = -0.55, p less than 0.02) indicated that the more was impaired resting left ventricular function, the more was decreased exercise capacity. Also, a significant correlation of systolic blood pressure at the end-point in exercise test with % FS (r = 0.58, p less than 0.005) or with % SIS (r = 0.69, p less than 0.001) indicated that inadequate blood pressure response might be partially attributed to impaired left ventricular function during exercise. The response of heart rate at the Bruce protocol stage I correlated with % FS (r = -0.67, p less than 0.001) and with % SIS (r = 0.53, p less than 0.02), respectively. These findings may be interpreted as chronotropic compensatory mechanism for limited stroke volume during exercise in patients with imparied left ventricular function. Thus, it was concluded that resting left ventricular function assessed by non-invasive cardiac examinations may predict exercise capacity prior to the test to some extent. These informations can be utilized for the decision of the planning at cardiac rehabilitation and also for the guidance in daily activities. Additionally, low level exercise test with treadmill is considered to be valuable for screening cases with impaired left ventricular function in old myocardial infarction.

Adult↗
PubMed1982

[Evaluation of left ventricular function in patients with dilated cardiomyopathy by exercise echocardiography].

In order to evaluate left ventricular function of dilated cardiomyopathy, 24 patients and ten healthy subjects were studied by exercise echocardiography. The patients with dilated cardiomyopathy were classified into 3 groups according to the presence or absence of mitral regurgitation and the severity of left ventricular dilatation: Group I was consisted of five cases with mitral regurgitation. Group II was consisted of seven cases without mitral regurgitation who had marked left ventricular dilatation, where the left ventricular end-diastolic dimension index (DdI) was greater than 46 mm/m2 and left ventricular end-systolic dimension index (DsI) was greater than 40 mm/m2. Group III was consisted of 12 cases without mitral regurgitation who had moderate left ventricular dilatation, where the DdI was less than 46 mm/m2 or DsI was less than 40 mm/m2. The ergometer exercise tests were performed for 3 min at 25 watts in a supine position. There was no significant differences of exercise-induced increases in heart rate, elevations of systolic blood pressure and increases of rate pressure product, respectively, between healthy subjects and each group of dilated cardiomyopathy. In healthy subjects, both DdI and DsI were unchanged on exercise. In Group I, DdI was unchanged but DsI decreased (p less than 0.02), thus percent fractional shortening of the left ventricle (delta D) was increased (p less than 0.05). In Group II, both DdI and DsI were unchanged. In Group III, DdI was increased (p less than 0.05) while DsI was unchanged, thus delta D was increased (p less than 0.02). These results suggested that the left ventricle is able to respond to exercise by its further dilatation (increase of preload) in mild to moderate dilated cardiomyopathy (Group III). On the other hand, in cases with marked left ventricular dilatation (Group II), the further dilatation is not induced. The same was true in dilated cardiomyopathy with mitral regurgitation (Group I), where the left ventricle had almost the same size as in Group II, although changes in DsI and delta D were not evaluated precisely because of the associated regurgitation.

Blood Pressure↗
PubMed1981

Studies on the preventive method of lowered ventricular fibrillation threshold during experimental acute myocardial infarctions. A comparison between disopyramide phosphate and lidocaine.

This study was performed to investigate the prophylactic effect of disopyramide phosphate on ventricular fibrillation in acute myocardial infarction. Lidocaine and disopyramide phosphate were compared in terms of their effects on the lowered ventricular fibrillation threshold in experimental myocardial infarction produced by coronary ligation in dogs. The following results were obtained: 1) The effect of lidocaine i.v. + infusion appeared promptly and the ventricular fibrillation threshold exceeded control levels from 45 min onwards (p less than 0.01). 2) The i.m. injection of lidocaine was effective in a dose of 10 mg/Kg. The minimally effective blood level was 1.7 mcg/ml. 3) Disopyramide phosphate 5 mg/Kg i.v. produced a tendency towards recovery from 15 min onwards. After 30 min, the ventricular fibrillation threshold was significantly higher than control (p less than 0.01). 4) Disopyramide phosphate 5 mg/Kg i.m. was initially effective after 45 min. The effect was significant from 1 hour and 30 min onwards, compared with control (p less than 0.01). The minimally effective blood level was 2.4 mcg/ml. 5) Disopyramide phosphate 2 mg/Kg i.m. produced a tendency towards recovery but the difference from the control was not significant. 6) In equivalent i.m. doses, disopyramide phosphate tended to be more potent than lidocaine in increasing the ventricular fibrillation threshold. 7) In the aforementioned doses, disopyramide phosphate did not cause any marked changes in PQ interval or QT time in ECG. These results suggest that the intramuscular injection of disopyramide phosphate is a hopeful clinical treatment to prevent ventricular fibrillation in the very early stages of acute myocardial infarction.

Animals↗
PubMed1980

An electrographic study on the functional capacity of the coronary collateral circulation in dogs with chronic coronary occlusion.

The functional capacity of coronary collaterals was investigated under resting and stress conditions in 15 dogs with chronic occlusion of the anterior descending coronary artery. ST-elevation in epicardial and intramyocardial electrograms was used for assessing the degree of regional myocardial ischemia. In resting condition, epicardial and intramyocardial electrograms from collateral, intermediate and circumflex areas revealed no significant ischemic changes. In 6 of 15 dogs in which atrial pacing was performed, ST-elevation appeared in electrograms from collateral and intermediate areas. In another 9 dogs, pacing tachycardia produced no significant changes in all electrograms. In these dogs more than 50% constriction of the donor coronary artery was necessary to induce ST-elevation in electrogram from collateral area. These findings indicate that the coronary collateral vessels in dog play beneficial role to prevent the myocardium from ischemic injury under stress condition, although their functional capacity is not comparable to that of normal coronary artery.

Animals↗
PubMed1980

A study on myocardial ischemia in the left ventricular wall with special reference to electrographic and metabolic changes.

Ischemic changes in the left ventricular wall were investigated during graded coronary constriction in 9 dogs. Epicardial and intramyocardial electrograms were recorded and changes in ST-segment voltage were correlated with the changes in intramyocardial gas tensions in outer and inner layers of the myocardium measured using a mass spectrometer. Electrographic and metabolic changes appeared first in inner layer and proceeded to outer layer with increasing severity of coronary constriction. In both layers intramyocardial ST-segment elevation was closely related with the increase in carbon dioxide tension (r = 0.78 in inner layer and r = 0.67 in outer layer). Epicardial electrogram, however, reflected the regional ischemia less sensitively than intramyocardial electrograms and has a limited function to detect myocardial ischemia.

Animals↗