In 72 patients satisfying the vectorcardiographic criteria described by Young et al, ²⁾ vectorcardiographic findings were compared between a group of patients with an inferior myocardial infarction and a false positive group to increase the specificity of the vectorcardiographic diagnosis of inferior myocardial infarction. The first group was composed of 18 cases, with angiographic findings of inferior myocardial infarction and the false positive group was composed of 54 cases which had no significant narrowing of coronary arteries.
Vectorcardiographic parameters such as the angle between the X axis and maximal QRS vector, the duration of initial superior force, the maximal superior deviation (QY) and the maximal inferior deviation (RY) were analyzed and only QY and QY/RY showed statistically significant differences between the 2 groups. Of these two parameters, QY/RY indicated a more definite difference. In addition, the rate of false positive cases was reduced prominently if the criterion of QY/RY above or equal to 0.2 was added to the criteria of Young et al. The direction of the maximal T vector was downward in 2 cases (11%) in the inferior myocardial infarction group, but downward in 44 cases (81%) in the false positive group.

View full abstract

Twenty patients with hypertension were studied under diets containing low and high salt to identify factors which might be involved in elevating blood pressure under sodium-loading. They were classified as "salt-sensitive" (SS) and "nonsalt-sensitive" (NSS) according to the presence or absence of greater than 10% increases in mean blood pressure when a low salt diet was replaced by a high salt diet. During high-sodium intake, the SS patients showed reduced urinary excretion of sodium and elevated plasma levels of aldosterone as compared with plasma renin activity. The SS patients also showed an enhanced pressor response to norepinephrine under both low-sodium and high-sodium diets.
From these results, it is suggested that the sodium retention, which is probably related to nonsuppressed levels of PAC under sodium-loading, is one of the factors in elevating blood pressure in the SS patients. Moreover, the enhanced pressor response to norepinephrine seems to contribute, in part, to elevation of blood pressure in the SS patients under salt-loading.

View full abstract

The effects of drugs were evaluated in 47 cases with variant angina (VA), 19 with resting angina showing ST depression (RA), and 84 with unstable angina (UA). In VA patients, calcium antagonists were effective in 87.1% of the cases, while other drugs were effective in 56.3%. The difference was statistically significant. In RA patients, calcium antagonists were effective in 80.0% of the cases and other drugs in 44.4%. Nifedipine was effective in all 5 cases of VA without marked coronary stenosis, and in 83.7% of VA cases with coronary stenosis of more than 75.0%. All cases of RA had multiple vessel disease and nifedipine was effective in 80.0% of the patients. Nifedipine was effective in 83.3% of VA cases showing ST elevation during an exercise test, and was particularly effective in all patients having attacks only at rest. The effects of nifedipine were confirmed in 83.8% of UA cases. These results indicate that calcium antagonists are effective in VA, RA, and UA.

View full abstract

Seven patients with right precordial Q waves (RPQs) simulating anterior myocardial infarction (MI), but without a previous history of either MI or other underlying diseases showing RPQ, were injected intravenously with ajmaline. The RPQs were abolished in 5 patients. Two patients displayed a transient, spontaneous abolition of RPQ, and 2 patients had false positive ST responses to the exercise test. Ajmaline injection in patients with documented MI and in patients with normal electrocardiograms did not produce any notable changes in the initial part of QRS complex. The RPQs abolished by ajmaline were probably a result of a mild preexcitation, induced by Mahaim fiber conduction, because the PR and QRS intervals were normal and low amplitude delta waves were found in some patients. It is important to note that altered intraventricular conduction, probably a mild preexcitation, can markedly deform electrocardiograms and mimic myocardial infarction.

View full abstract

To determine the effect of acute myocardial infarction (AMI) on serum and urinary activity of β-galactosidase and β-glucuronidase (lysosomal enzymes) 40 patients were studied. Eighteen patients had acute myocardial infarction and 22 were assigned as controls. Three of the 18 patients with acute myocardial infarction died within 5 to 10 days after hospitalization. Although the serum and urinary β-glucuronidase and serum β-galactosidase activity was higher in patients with acute myocardial infarction when compared with the control subjects these differences did not achieve statistical significance. However, the mean values of urinary β-galactosidase in the control and acute MI groups were 158.68 and 333.3nmol/mg creatinine/hr, respectively (p<0.046). These findings indicate that there is a significant increase in the urine β-galactosidase activity during the early phases of acute myocardial infarction.

View full abstract

Effects of three representative vasodilators on peripheral and cardiac hemodynamics were studied in 20 patients with heart failure due to acute myocardial infarction (PCWP>18mmHg, Cl>2.20L/min/m²) using venous occlusion plethysmography and a Swan-Ganz catheter. Sublingual isosorbide dinitrate (ISDN) significantly increased calf venous capacitance (CVC) from 5 to 60min (p<0.01) and calf blood flow (CBF) in the initial 15min (p<0.05), while simultaneously lowering PCWP (p<0.05) and central venous pressure (p<0.05). Calf vascular resistance (CVR), cardiac index, blood pressure, and total systemic peripheral resistance (TSPR) were not affected significantly. Nitroglycerin ointment (NGO) significantly decreased CVR (p<0.05) and increased CVC (p<0.05) from 60 to 240min, simultaneously with lowering of PCWP (p<0.01), central venous pressure (p<0.05), and TSPR (p<0.05). Oral prazosin (Pz) increased CBF (p<0.01) and CVC (p<0.05) from 60 to 240min, simultaneously with significant lowering of PCWP (p<0.01) and TSPR (p<0.05), resulting in increased stroke work index (p<0.05). These data confirm that ISDN predominantly causes capacitance vessel dilatation and reduce excessive venous return, while Pz and NGO dilate not only capacitance vessels but also resistance vessels, consequently reducing systemic vascular resistance and resulting in increased peripheral blood flow and cardiac performance. It was observed that the higher the base-line calf vascular resistance rose, the better the response to the vasodilator treatment appeared in terms of a decrease in calf vascular resistance.

View full abstract

The surface morphologic features of the lung obtained from 21 patients with various forms of heart disease were investigated by scanning electron microscopy, with particular emphasis on the correlation between the surface pathology and cardiopulmonary hemodynamics. There were almost no pathologic findings on the bronchiolar and alveolar surfaces in patients with normal pulmonary arterial wedge pressure (PAWP). The characteristic changes of the surface morphology of the lung parenchyma in patients with abnormal elevation of PAWP included various degrees of desquamating loss of the bronchiolar epithelium associated with inflammatory cell infiltration and fibrotic changes and focal epithelial disruption of the individual alveoli which often extended to involve the surface of the entire alveoli with perforated rupture of the alveolar septa. The severity of abnormal surface morphologic findings of the lung seemed to correlate to the degree of PAWP. From our results it is concluded that chronic lung congestion plays a major role in the pathogenesis of the surface pathologic changes of the lung in patients with heart disease of various etiologies. Our findings may provide a clearer understanding of the structural and functional relationship of congestive lung and a clinical explanation for pulmonary manifestations in patients with chronic congestive heart failure.

View full abstract

After unilateral nephrectomy and bilateral adrenal enucleation at 5 weeks of age, salt-loaded rats developed hypertension (ARH) at 6 weeks. Fibrous vascular protein and in vivo incorporation of ³H-lysine into this protein fraction were measured at 15 weeks of age in these animals.
This study demonstrates: (1) that incorporation rates of ³H-lysine into cardiac collagen and elastin in ARH rats were greater than in control rats (p<0.001, respectively), and (2) that administration of phenoxy-benzamine hydrochloride decreased the incorporation of tritiated lysine into cardiac collagen in ARH rats, concomitant with a reduction in blood pressure. Based on these findings, increased synthesis of cardiac collagen and elastin appears to play an important role in the development of hypertension in ARH.

View full abstract

We investigated the vasodilating effects of verapamil, nifedipine, and nitroglycerin in relation to plasma levels of 6-keto-prostaglandin (PG)-F_1α, PG E₁, PG F_2α, and thromboxane (TX) B₂ in dogs. Verapamil, nifedipine, and nitroglycerin decreased peripheral vascular resistance from 1.00±0.07mmHg/ml/min (mean±SE) to 0.83±0.05, from 0.99±0.06 to 0.80±0.05, and from 1.03±0.04 to 0.91±0.04, respectively. However, peripheral blood flow did not change significantly. Administration of verapamil significantly increased plasma levels of 6-keto-PG F_1α, PG E₁, and PG F_2αfrom 150±31pg/ml to 350±98, from 56±34 to 87±33, and from 127±35 to 238±61, respectively, while neither nifedipine nor nitroglycerin had any effect on plasma 6-keto-PG F_1α, PG E₁, and PG F_2α. Indomethacin pretreatment reduced the effects of verapamil on peripheral vascular resistance and plasma PG concentration. None of these drugs caused a significant change in the plasma TX B₂ level. The results suggest that the vasodilating action of verapamil was mediated in part by the prostaglandin system.

View full abstract

This study was designed to determine how distal vasodilatory stimuli can alter coronary hemodynamics and the appearance of myocardial ischemia in the presence of severe coronary stenosis. In anesthetized open chest dogs, left circumflex coronary artery (LCx) flow, distal LCx perfusion pressure (DCPP), heart rate, and aortic pressure were monitored and regional myocardial ischemia was estimated from ST segment deviation in the epicardial and intramyocardial electrograms obtained from the electrodes located in the area supplied by LCx. In the presence of severe LCx constriction, intracoronary administration of adenosine (0.01mg/Kg/min) and dipyridamole (0.05mg/Kg) failed to augment LCx flow and induced further reduction in DCPP without changing systemic hemodynamics. In parallel with these hemodynamic changes, significant ST elevation was observed in the inner layer of the area supplied by the LCx. These results show that subepicardial vasodilation following vasodilatory stimuli can induce transmural flow redistribution and lead to subendocardial ischemia in the presence of severe coronary stenosis.

View full abstract

The electrophysiological and inotropic effects of Coenzyme Q₁₀ (CoQ₁₀) on isoproterenol or barium-induced slow responses in ventricular papillary muscle, depolarized by high K⁺ concentration (21.6mM) under hypoxia (PO₂_??_40mmHg), were studied with microelectrode techniques. For the isoproterenol-induced slow response, application of CoQ₁₀ (50μg/ml), which was emulsified with the aid of a special solvent, increased the maximum rate of rise of action potentials (V_max), an indicator of the slow inward current, by about 40%, with no consistent effect on the action potential duration and developed tension. Application of the solvent alone produced a significant decrease in both V_max and developed tension. However, in these solvent-pretreated preparations, CoQ₁₀ produced a significant (by about 50%) recovery in both V_max and developed tension. The action potential duration was not changed by either the solvent alone or the application of CoQ₁₀. The developed tension of the slow response consisted of early and late components. CoQ₁₀ produced significantly more recovery in the late component than in the early one, suggesting that the recovery effect was due to increased slow inward Ca²⁺ current. CoQ₁₀ did not reverse any parameter in the slow response induced by BaCl₂ (0.2mM). The results suggest that CoQ₁₀ has significant but limited reversing effects on the hypoxia-induced deterioration of the slow response, and that the recovery is presumably due to increased availability of slow channels via increased production of ATP.

View full abstract

The cardiac effects of amrinone were studied in 5 heart-lung preparations of the dog. Amrinone improved the cardiac performance during pentobarbital-induced heart failure.

View full abstract

Cardiovascular effect of a new compound, K 351, was examined in anesthetized dogs. Intravenous injections of 100μg/Kg or over of K 351 caused a fall in systemic blood pressure, reduced peripheral vascular resistance, left ventricular enddiastolic pressure, max dP/dt and Vmax, and increased time constant T and PQ interval. Heart rate was reduced with 1μg/Kg K 351. The magnitudes of the changes in heart rate, T and PQ interval were not different between K 351 and propranolol groups, while those in max dP/dt and Vmax caused by K 351 were larger than those induced by the same doses of propranolol. It is suggested that K 351 suppressed left ventricular contractility, sinus node activity and atrioventricular conduction through its β-receptor blocking action and reduced peripheral vascular resistance and left ventricular enddiastolic pressure through its vasodilating action.

View full abstract

The purpose of this study is to determine the effects of different kinds of assisted circulation (AC) on the intensity of ischemic and necrotic processes in experimental myocardial infarction in dogs. Three types of experiments were carried out. In the first group, the infarction was modelled by surgical ligation of a branch of the descending artery. In the second group, AC by intraaortic balloon counterpulsation was started 15min after coronary occlusion and lasted for 2 hours. In the third group, AC was carried out by means of left ventricular drainage with transaortic insertion of a catheter, and a subsequent forcing of the blood into the femoral artery. During the experiment, 10 piecardial leads were recorded tandhe number of points registering a considerable displacement of seTgment S (nST) as well as the total displacement of segment ST (ΣST) were analysed. The size of the necrotic zone in the myocardial wall was identified macroscopically.
The results testify to the favourable effects of both methods of AC on the intensity of destructive myocardial processes. The effect on ST was recorded soon after the beginning of AC. The effect on ΣST was less pronounced and was observed at a later stage (after 30-45min). In the histochemical investigation of the necrotic zone of the myocardial wall, the positive effects were more marked in the extracorporeal bypass of the left ventricle, which showed the size of myocardial infarction to be much smaller (p<0.05) than in the group with intraaortic balloon pumping. These experimental data are indicative of a significant positive effects of AC. In particular, shunting of the left ventricle caused a marked decrease in myocardial necrosis.

View full abstract

The authors performed a number of experiments aiming at quantifying the infarct size in Sprague-Dawley male rats. The experimental model employed was isoproterenol (ISP) induced, infarctlike myocardial lesions. In quantifying the extent of the infarct area they compared the cross reliability of enzymatic and histological methods.
ISP was administered in two subcutaneous injections (50mg/100Gm body weight) at a 24 hour interval. At the peak of the necrotic process (48hrs after the first injection), the heart was subjected to enzymatic or histological studies. Thus, a group of infarcted animals (n=25) and their controls (n=15) underwent the assessment of creatine kinase (CK) content in the homogenate of the myocardium. Another group of animals (n=15) was used for histological observations, including measurement of infarct size by planimetry from histological sections. A good relationship was observed between the percentage of necrotic tissue calculated on the basis of CK values (69.11±2.39%) and the infarction area assessed by planimetry (72.37±2.69%) (mean±standard error of the mean [SEM]).
Thus, the present study confirms that ISP-induced myocardial lesions are a simple and reliable model for experimental infarct. Moreover, the assessment of the CK content in the heart is correlated with histological studies by planimetry, and is suggested as a direct enzymatic method to quantify the extent of myocardial necrosis.

View full abstract

This report describes the findings in a young woman with Takayasu's disease, resulting in angina pectoris due to severe narrowing of the left coronary ostium. The patient underwent aortocoronary bypass surgery. The disappearance of angina, with reversal of positive findings on the treadmill exercise test, was noted postoperatively. Selective coronary angiography should be performed in patients with Takayasu's disease with a positive exercise test and symptoms of chest pain.

View full abstract

A case of cough syncope due to A-V conduction block of the heart is reported in this paper. A-V conduction block and lightheadedness were induced by coughing but not by an Aschner test, carotid sinus massage, Valsalva maneuver, pharyngeal stimulation, and stimulation of systemic baroreceptors. Permanent right-ventricular pacing completely abolished the patient's symptoms. The results suggest that hypersensitivity of a broncho-pulmonary reflex to coughing was responsible for the A-V conduction block and resulting syncopes.

View full abstract

Dibutyryl cyclic AMP was administered to 2 patients with severe congestive heart failure. After an intravenous drip infusion of dibutyryl cyclic AMP (300mg/40min), marked diuresis and mild improvement of the patients' physical activity occurred. The cardiac index increased and both systemic vascular resistance and pulmonary capillary wedge pressure decreased. Blood glucose and plasma insulin increased simultaneously, while plasma free fatty acid decreased during the infusion. A continuous intravenous micro-infusion of dibutyryl cyclic AMP (300mg/24h) also exerted diuresis and improved physical activity. The hemodynamic and metabolic effects of dibutyryl cyclic AMP are expected to be beneficial to a failing heart.

View full abstract