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Biomedical subjects

H Fukuzaki

Publications and source records attributed to H Fukuzaki.

At least 217 records · Page 12Linked to original sources
PubMed1985

[201T1 computed tomography using dipyridamole for assessing dilated cardiomyopathy].

The value of redistribution thallium-201 (T1-20(1] emission computed tomography (ECT) using dipyridamole for evaluating coronary circulation was analyzed in 18 patients with dilated cardiomyopathy (DCM). After maximal inducible coronary vasodilation (dipyridamole, 0.56 mg/kg), 2 mCi T1-201 was administered, and dipyridamole ECT data at 10 minutes and delayed ECT data at 3 hours after the injection were collected. Image interpretation was made visually. The results were as follows: In all cases, perfusion defects were observed on the dipyridamole images, and eight (45%) had redistribution on their delayed images. Patients with redistribution had better left ventricular function (% fractional shortening 24.7 +/- 7.0 versus 18.0 +/- 5.0) by two-dimensional echocardiography. Segments with redistribution showed less severe wall motion abnormalities compared with segments without redistribution. It is concluded that redistribution thallium ECT imaging using dipyridamole is a useful tool for the evaluation of coronary circulation of patients with DCM.

Cardiomyopathy, Dilated↗
PubMed1985

[Clinical significance of early redistribution of the exercise-induced thallium-201 defect in ischemic heart disease].

This study clarified thallium-201 (Tl) kinetics in the early stage after exercise in patients with ischemic heart disease (IHD). Tl was administered for 39 patients with IHD and eight normal subjects during maximal exercise. Immediately after exercise, dynamic data were obtained using a double slant-hole collimator at one frame/2 min for a 20 min period. The data of 10 frames (20 min) were spatially smoothed, and semiquantitative segmental analyses of the uptake and kinetics of Tl were performed by computer. In eight normal subjects, Tl uptake was uniform throughout the continuous 20 min, and Tl activity was unchanged throughout the 20 min period after exercise. Among 39 patients with IHD, 39 had Tl defects in the first frame (initial defect). Among 39 initial defects, 15 (38%) showed complete or partial early redistribution as early as 20 min and Tl activity in the defect increased (10.5 +/- 1.5%) over the 20 min period. Early redistribution occurred in 10 (43%) of 23 patients with effort angina and in five (83%) of six patients with variant forms of angina, but in no patients with myocardial infarction. Patients with early redistribution showed a greater frequency either of good collateral vessels or of mild stenosis of the coronary artery, compared with those who had no early redistribution. In conclusion, analysis of Tl kinetics in the early stages after exercise can provide important information about the coronary perfusion state during recovery from transient ischemia, and early redistribution may be a sign of preserved hyperemic flow in the ischemic region.

Angina Pectoris↗
PubMed1985

Effects of nifedipine on coronary vasculature in canine models of dynamic and fixed coronary stenoses.

The effects of nifedipine were examined in dogs with flow-limiting dynamic and fixed coronary stenoses. During dynamic coronary stenosis, produced by an intraluminal microballoon occluder which preserved active vasomotion in a stenosed segment of a proximal left circumflex coronary artery, intracoronary infusion of nifedipine (0.01 and 0.1 microgram/kg/min) increased coronary blood flow (CBF) by 15 +/- 5.0% (P less than .05) and 50 +/- 11.6% (P less than .01), respectively (mean +/- S.E.) and reduced stenosis resistance (SR) resulting in the alleviation of myocardial ischemia due to preferential vasodilation of large coronary arteries. In contrast, nifedipine (1.0 microgram/kg/min) did not increase CBF and reduced distal coronary pressure associated with intensified SR mainly due to arteriolar vasodilation. During fixed coronary stenosis created by external application of an occluder device, all doses of nifedipine failed to affect CBF and SR. Intravenous nifedipine (3 micrograms/kg) caused a biphasic response during dynamic coronary stenosis; an initial transient decrease and a late sustained increase in CBF concomitant with a transient augmentation and a subsequent prominent reduction of SR. These results suggest that nifedipine is capable of preferentially dilating large epicardial coronary arteries and reducing stenosis severity resulting in the relief of myocardial ischemia during pliable coronary stenosis, and this mechanism may contribute to the beneficial effects of nifedipine in clinical ischemic syndrome.

Animals↗
PubMed1985

[Regional right ventricular hypertrophy in hypertrophic cardiomyopathy and hypertension].

The mode of right ventricular hypertrophy was assessed by two-dimensional echocardiography (2DE) for 24 patients with hypertrophic cardiomyopathy (HCM), and the results were compared with those of 51 patients with hypertension (HT). The patients with HT were categorized in four groups depending on the thickness of the interventricular septum (IVST) and left ventricular posterior wall (PWT): HT-ASH with both left ventricular hypertrophy (LVH) (IVST greater than or equal to 13 mm) and asymmetric septal hypertrophy (ASH) (IVST/PWT greater than or equal to 1.3), severe HT with LVH and without ASH, and mild HT without LVH and ASH. Anterior wall thickness (AWT), posterior wall thickness (PWT), and diaphragmatic wall thickness (DWT) of the right ventricle were obtained from 2DE in the parasternal long-axis view, the short-axis view and subxiphoid view, respectively. These were recorded on video tape, and the measurements were made on the stop frames. Right ventricular hypertrophy (RVH) was estimated by the maximal right ventricular wall thickness (max RVWT), and the ratio of the maximal and minimal thickness (max RVWT/min RVWT) was calculated to evaluate asymmetrical hypertrophy (AH) of the right ventricle (RV). The incidence of RVH (Max RVWT greater than or equal to 5 mm) and asymmetrical hypertrophy (AH) (max RVWT/min RVWT greater than or equal to 1.3) of the RV in HCM, HT-ASH and mild HT were 67% and 41%, 57% and 45%, and 15% and 11%, respectively. The incidence of RVH with AH was more frequent in patients with HCM as well as HT with ASH than in patients with HT without ASH.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Volume↗
PubMed1985

[Regional left ventricular function in dilated cardiomyopathy: observation of regional left ventricular wall motion before and during dobutamine administration].

To investigate left ventricular function and the prognosis of patients with dilated cardiomyopathy (DCM), regional wall motion of the left ventricle of 38 patients with DCM was observed before and during dobutamine infusion (8 micrograms/kg X min) by two-dimensional echocardiography (2DE). The left ventricle was divided into 11 segments and the severity of wall motion abnormality (WMA) was classified into 4 grades, i.e. akinesis or dyskinesis (A), severe hypokinesis (SH), hypokinesis (H) and normokinesis (N), and numerical scores were assigned to each grade of WMA as follow; A: 3, SH: 2, H: 1, and N: 0. In the 38 patients with DCM, the number of segments with WMA was 8.3 +/- 2.9 (mean +/- SD). Among 418 segments in the 38 patients, we observed A in 71 segments, SH in 104 segments, H in 140 segments, and N in 103 segments. The WMA was not uniform in the left ventricle, and severe WMA was observed in the apex (WMA score: 2.0 +/- 1.0), while the grades of WMA in the lateral and posterior walls were mild (WMA score: 0.8 +/- 1.1) compared with those of other segments. The total sums of the WMA scores in 11 segments for each patient (TWMAS) were significantly greater in patients with severe heart failure (New York Heart Association [NYHA] functional class III or IV) than in patients with mild heart failure (NYHA class I or II) (22.0 +/- 5.2 and 9.9 +/- 4.9, p less than 0.001). TWMAS correlated with the cardiac index (CI) (r = -0.58, p less than 0.005) and pulmonary capillary pressure (PCP) (r = 0.68, p less than 0.001). In 242 segments of 22 patients, whose regional wall motion was observed before and during dobutamine administration, wall motion was improved by one grade in 82 of 170 segments with WMA before dobutamine infusion; i.e. regional wall motion changed from A to SH in six segments, from SH to H in 31 segments, and from H to N in 45 segments with dobutamine administration. According to the change in grade of TWMAS induced by dobutamine administration, 22 patients with DCM were classified into two groups: a good response group (% change of TWMAS greater than or equal to 40%), and a poor response group (% change of TWMAS less than 40%). The poor response group had ventricular tachycardia more frequently, more severe heart failure, lower CI and higher PCP than the good response group.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1984

Age-associated increments in human platelet alpha-adrenoceptor capacity. Possible mechanism for platelet hyperactivity to epinephrine in aging man.

In order to evaluate the effects of aging on platelet alpha-adrenergic receptor function, we have examined the binding of [3H]dihydroergocryptine ( [3H]DHE), a nonselective alpha-adrenergic antagonist, to crude platelet membrane at 25 degrees C in 28 subjects of various ages (mean 48, range 21-77 years) and platelet aggregatory response to epinephrine in other 32 subjects of various ages (mean 51, range 27-82 years). The average values of the binding capacity and affinity for [3H]DHE showed 218 +/- 56 fmol/mg protein (mean +/- SD) and 1.80 +/- 0.20 nM, respectively. There was a significant correlation between the binding capacity for [3H]DHE and age (r = 0.654, p less than 0.001). On the contrary, no significant correlation was found between the binding affinity for [3H]DHE and age (r = 0.273, p greater than 0.1). Exaggerated aggregatory response to epinephrine with advancing age was also demonstrated in this study (r = 0.716, p less than 0.001). Thus, the demonstration of increased alpha-adrenergic receptor capacity in aging man offers a possible explanation for the observed age-associated hyperactivity of the platelets to epinephrine.

Adult↗
PubMed1984

Inhibitory action of guanosine 3',5'-monophosphate on thrombin-induced calcium mobilization in human platelets.

During thrombin-induced serotonin release from platelets, phosphorylation of myosin light chain was increased. This protein phosphorylation, which is initiated by Ca2+ mobilization, and serotonin release were inhibited progressively by increasing concentrations of sodium nitroprusside, a potent stimulator of platelet guanylate cyclase, or 8-bromo-cyclic GMP. Thrombin-induced increase in cytoplasmic free Ca2+, which was also inhibited by these drugs in a dose-dependent manner. These results provide evidence that an increase in platelet cyclic GMP inhibits thrombin-induced Ca2+ mobilization and prevents platelet activation.

Blood Platelets↗
PubMed1984

Mixed connective tissue disease with fatal pulmonary hypertension and a review of literature.

The paper presents an autopsy case of mixed connective tissue disease (MCTD) with pulmonary hypertension (PH) and a review of literature. A 33-year-old woman with Raynaud's phenomenon and dyspnea of one year duration was diagnosed as having MCTD on the basis of a higher titer (1:163,840) of serum antibodies to the ribonucleoprotein (RNP). Cardiac catheterization showed complicating PH, confirmed an autopsy by the findings of concentric intimal cellular proliferation and typical plexiform lesions in the small arteries and arterioles of the lung, suggesting primary PH. Fatal PH with MCTD has been reported only 6 cases in literature including our case. All were young females, with histopathological findings consistent with plexogenic pulmonary arteriopathy in 5 cases and with recurrent pulmonary thromboembolism in the other. The aetiology of PH is still unknown, but it may be due to vasoconstriction evoked by the hyper-reactivity of the vessels.

Adult↗
PubMed1984

Effect of hypoxia on cholesterol accumulation in cultured rabbit aortic smooth muscle cells.

We studied the effect of hypoxia on cholesterol accumulation in cultured rabbit aortic smooth muscle cells, which were incubated in a medium with normolipemic rabbit serum (NRS) or hyperlipemic rabbit serum (HRS). The cells were incubated in a humidified atmosphere of either 20% O2, 75% N2 and 5% CO2 (control cells) or 2% O2, 93% N2 and 5% CO2 (hypoxic cells). In a medium containing 20% NRS, the free cholesterol level of hypoxic cells was only a little higher than that of control cells, and there was no significant difference in esterified cholesterol content. On the other hand, in a medium containing 20% HRS, the free cholesterol level was slightly higher and the esterified cholesterol level was markedly higher in hypoxic cells compared with control cells. These results show that hypoxia promotes the accumulation of cholesterol, especially as ester, in smooth muscle cells cultured with hyperlipemic serum. These in vitro experiments indicate that hypoxia in the arterial wall associated with hyperlipidemia may play an important role in atherogenesis, although the precise mechanism remains unclear.

Animals↗
PubMed1984

A long-term follow-up study of acute myocarditis an electrocardiographic and echocardiographic study.

In an attempt to prove that myocarditis may be a cause of idiopathic cardiomyopathy, 10 cases with acute myocarditis were involved in a long-term follow-up study. There were 9 males and 1 female patient, ranging in age from 22 to 63 years. The etiology of myocarditis was idiopathic in 9 cases and rubella virus in 1 case. Clinical findings in the acute stage consisted of congestive heart failure in 6 cases, Adams-Stokes syndrome in 2 cases and cardiomegaly in 2 cases. The mean follow-up period was 55 months. Follow-up studies included physical examinations, 12-lead ECG, chest X-rays and two-dimensional echocardiograms. Various patterns of residual ECG abnormalities in the chronic stage were found, such as conduction disturbance in 1 case, pseudoinfarction pattern in 4 cases, ST-T changes in 2 cases and premature ventricular contractions in 2 cases. The cardiothoracic ratio of all cases was 60 +/- 4% in the acute stage. Two cases (Case 1 and 2) died 16 and 36 months after the acute onset, respectively. Four cases had residual cardiomegaly even in the last study period. An echocardiographic follow-up study of 7 cases disclosed progressive left ventricular (LV) dilatation and dysfunction in 3 cases, regression of LV dilatation in 2 cases and stable LV function in 2 cases. Two cases out of 3 with progressive LV dilatation and dysfunction expired after the acute illness. It was therefore suggested that acute myocarditis may cause LV dilatation and/or wall hypertrophy and that idiopathic cardiomyopathy may represent the end-stages of previous myocarditis.

Acute Disease↗
PubMed1984

Arrhythmia in young patients with mitral valve prolapse.

Twenty four-hour ambulatory ECG monitoring were examined in 68 patients (33 patients in a young group and 35 patients in an adult group) with mitral valve prolapse (MVP) in order to characterize the features of arrhythmias in young patients with MVP in comparison with those in adult patients. Diagnosis of MVP was made by two-dimensional echocardiography. On 24-hour ambulatory ECG monitoring 29 patients (88%) in a young group had arrhythmias which was as frequent as those in adult group, but serious ventricular arrhythmias were more often detected in the young group (7 patients) than in the adult group (2 patients). It was considered that arrhythmias in young patients with MVP were frequently serious but accompanied without any symptoms and cardiac dysfunction.

Adult↗
PubMed1984

The effect of isosorbide dinitrate on exertional hypotension in old myocardial infarction.

Four patients with old myocardial infarction (OMI) revealed exertional hypotension in the treadmill exercise test. All had a multivessel disease, severe left ventricular dysfunction and exercise-induced ST depression or angina to indicate additional myocardial ischemia. After 5 mg of oral isosorbide dinitrate (ISDN), the response of blood pressure was improved with a delayed onset of ST depression or angina. To confirm the effect of ISDN on the pressure response to exercise, 26 patients with OMI were further studied. In patients without ST depression and angina (Group I), the systolic blood pressure (SBP) at the matched work load was significantly decreased after ISDN. However, in patients with ST depression or angina (Group II), SBP at the matched work load was not altered after ISDN. The increment of change in SBP due to ISDN, namely from the resting level to the matched work load, was significantly larger in Group II than in Group I. In addition, the patients with marked left ventricular dysfunction in Group I revealed a more change in SBP due to ISDN than the others in Group I. It was concluded that exertional hypotension or suppressed pressure response of OMI could be corrected by 5 mg of oral ISDN due to its favorable effects on the exercise-induced myocardial ischemia and preexisting left ventricular dysfunction.

Aged↗
PubMed1984

Assessment of left ventricular function in ischemic heart disease. The relation between pressure decay during the isovolumic relaxation phase and regional wall motion abnormality.

We examine whether regional wall motion abnormality (RWMA) could contribute to the slowed relaxation rate of the left ventricle (LV) in patients with coronary artery disease (CADpts). Simultaneous observations were made on the time constant (Tc) of the isovolumic pressure decay and left ventriculography at the control period and after right atrial pacing. Subsequently, the subjects investigated were divided into 3 groups, i.e. normal subjects (Group I, n = 8), CADpts with normal wall motion during the control period (Group II, n = 21), and CADpts with RWMA during the control period (Group III, n = 28). The latter two groups were further divided into two subgroups according to the presence (Group IIa and IIIa) or absence (Group IIb and IIIb) of pacing-induced RWMA. We measured Tc by a method of exponential analysis that could estimate the asymptote. During the control period, Tc was significantly prolonged in Group III (82 +/- 26 msec) than that in Group I (60 +/- 6 msec) and Group II (63 +/- 12 msec). Tc was prolonged in proportion to the extent of RWMA during the control period. Immediately after right atrial pacing, Tc was markedly prolonged in Group IIa (from 61 +/- 12 to 90 +/- 20 msec, p less than 0.001) and in Group IIIa (from 73 +/- 26 to 95 +/- 34 msec, p less than 0.001). The post-pacing prolongation of Tc was closely correlated with the extent of post-pacing RWMA. From these results, it is postulated that RWMA may play an important role as a causes of the altered LV relaxation in CADpts.

Adult↗
PubMed1984

Abnormal red cell sodium content and efflux in Japanese patients with essential hypertension.

Net sodium (Na) efflux and potassium (K) influx were determined in Na-loaded/K-depleted erythrocytes derived from 37 patients with essential hypertension and 25 age-matched normotensive subjects with no family history of hypertension, together with the measurement of basal red cell sodium and potassium contents. Intraerythrocyte sodium content was significantly higher in the essential hypertensives than in the normotensives (10.9 +/- 1.4 vs 10.0 +/- 1.2 mmol/L X cells, mean +/- SD, p less than 0.02), but potassium content was nearly equal between the two groups. Net Na efflux in the hypertensives was significantly reduced compared with that in the normotensives (4.57 +/- 0.70 vs 5.18 +/- 1.02 mmol/L X cells X hr, p less than 0.01), but both net K influx and net Na/K flux ratio were not significantly different between the two groups. Net Na efflux and K influx showed a significant inverse correlation with red cell sodium content (r = -0.64 and r = -0.56, respectively, p less than 0.001). These results suggest that the reduced net Na efflux with the increase of red cell sodium content may be related to the pathogenesis of essential hypertension. However, it is impossible to determine the genetic marker of essential hypertension by using the net Na/K flux ratio of Japanese subjects, although Garay et al. have reported that this index was abnormally low in the case of Europeans.

Adult↗
PubMed1984

The effect of nitrate on the oxygen availability during exercise in effort angina pectoris.

Respiratory responses during exercise were observed to determine whether improvement of oxygen availability in working skeletal muscle is attributable to increased aerobic capacity after administration of nitrate in patients with effort angina. After isosorbide dinitrate (ISDN) administration, the aerobic capacity increased 3.3 ml/min/Kg (20%) as compared with the control test (p less than 0.001), but the anaerobic threshold (AT), a good indicator of oxygen availability, was unchanged, and the respiratory quotient at the peak of exercise was elevated. These findings suggest that oxygen availability in skeletal muscle was not altered after ISDN, and increased exercise load accompanied increased anaerobic glycolysis. It was concluded that the nitrate-induced increase in aerobic capacity was not dependent upon the change in oxygen availability in skeletal muscle but rather upon the elevated anginal threshold.

Adult↗
PubMed1984

Contractile responses of canine coronary collateral vessels.

This study examines the responses of coronary collateral vessels to various vasoconstrictors and compares them with responses of 3 different divisions of the native coronary arterial trees in dogs. Only high concentrations of phenylephrine induced contractions in collateral vessels and medium coronary arteries, whereas even a high concentration of this agent did not affect small coronary arteries. Lower concentrations of serotonin or ergonovine elicited contractions in collateral vessels, and medium and large coronary arteries, but even a high concentration of these agents did not affect small coronary arteries. Angiotensin II (10(-7) M) elicited prominent contractions in the following order: small vessels, collateral vessels, medium and large coronary arteries. These results indicate that well-developed collateral vessels behave like native medium diameter coronary artery, and that the tonus of collateral vessels is possibly influenced by various vasoactive substances.

Angiotensin II↗