In order to examine the possible role of coronary artery spasm in the pathogenesis of unstable angina, provocative testing for coronary spasm was performed in 43 patients with unstable angina who had 0 -or 1-vessel disease. Coronary spasm was induced in 20 (65%) of 31 patients by hyperventilation testing (ST ↑ in 18, ST ↓ in 2). Anginal attacks with either ST-segment elevation or ST-segment depression in patients without a significant organic stenosis were induced in 23 (55%) of 42 patients during treadmill exercise testing. Coronary artery spasm, showing severe (_??_90%) vasoconstriction with angina and/or ischemic electrocardiographic ST-segment deviation, was also documented angiographically in 42 (98%) of 43 patients following intracoronary injection of acetylcholine. We conclude that dynamic coronary obstruction plays an important role in the genesis of attacks in patients with unstable angina who had 0- or 1-vessel organic coronary artery disease.

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To evaluate the safety and efficacy of catheter mediated radiofrequency (RF) ablation in patients with Wolff-Parkinson-White syndrome, 125 patients with accessory pathway (AP) mediated tachyarrhythmias underwent RF ablation. Right-sided APs were ablated from the atrial aspect of the tricuspid annulus (all from the femoral vein approach) and the left-sided APs were ablated from the atrial or ventricular aspect of the mitral annulus. Immediately after ablation, 3 of 8 APs (38%) and 131 of 137 APs (95%) were ablated successfully with RF through a small-tip (2mm) and a large-tip (4mm) electrode catheter, respectively. Seven of the 11 APs where RF ablation failed had a later successful DC ablation. During follow-up (3 to 22 months), 11 of the 114 patients (10%) with successful ablation had return of accessory pathway conduction (2 had recurrence of tachycardia (2%)). Complications included transient myocardial injury (peak CK-MB 15±3IU/l), transient proarrhythmic effects (more atrial and ventricular premature beats), accidental AV block (1 patient), cardiac tamponade (1 patient) and suspicion of aortic dissection (1 patient). In successful sessions, procedure and radiation exposure time were 3.8±0.2h and 45±4min, respectively. This study confirms that RF ablation with a large-tip electrode catheter is an effective and relatively safe nonsurgical method for treatment of Wolff-Parkinson-White syndrome.

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This study reports the clinical follow-up for 6 months of 52 patients who underwent percutaneous transvenous mitral commissurotomy (PTMC). PTMC resulted in an increase in mitral valve area from 1.1±0.3 to 1.7±0.4cm² (p<0.0001), a decrease in mean left atrial pressure from 16±7 to 13±5mmHg (p<0.0001), and an increase in exercise time from 4.6±2.1 to 6.3±2.3min (p<0.0001). At 6 months follow-up, mitral valve area was unchanged (1.7±0.4cm²). Of 52 patients, 33 showed clinical improvement and 19 had no clinical improvement after PTMC. Univariate analysis showed (1) younger age, (2) echocardiographic score of 8 or less, (3) existence of mitral regurgitation of less than grade 2 after PTMC, and (4) amelioration in left atrial dimension, mean pulmonary artery pressure and exercise time after PTMC as correlative factors for clinical improvement.
In conclusion, PTMC was an effective procedure for mitral stenosis, especially in younger patients with an echocardiographic score of 8 or less. Change in left atrial dimension was a good indicator of the effectiveness of PTMC.

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To evaluate the antihypertensive and hormonal effects of oral magnesium supplementation, 17 inpatients with untreated, uncomplicated mild-to-moderate essential hypertension (EH) and 8 age-matched normotensive controls (controls) were given MgO orally 3 times a day at a daily dose of 1.0g (0.6g per day as Mg) for a period of 2 weeks. Supplementation of MgO elicited a significant fall in averaged mean blood pressure calculated with a 24-h ambulatory blood pressure monitoring system (MBP) in EH from a baseline value of 104.3±12.2 to 99.5±11.6mmHg (p<0.05), while controls remained unaltered from a baseline value of 85.1±11.5 to 84.5±13.3mmHg. The percentage reductions in systolic and diastolic blood pressures were similar during daytime and nighttime in EH. According to the extent of reduction in MBP with magnesium supplementation, EH patients were divided into 2 groups, responder and nonresponder. The level of plasma renin activity (PRA) in the responder group was significantly higher than that of the nonresponder group (p<0.05). After 2 weeks of magnesium supplementation, the plasma level of Na⁺, K⁺-ATPase inhibitory activity (PATPI), defined as equivalency to ouabain, was reduced significantly from 0.75±0.54 to 0.40±0.30umol ouabain/ml (p<0.05) in the responder group, while it remained unaltered in controls and the nonresponder group. PRA, plasma aldosterone concentration, urinary epinephrine and norepinephrine excretion, and urinary sodium excretion did not change significantly in either control subjects or EH (responder and nonresponder groups). A significant negative correlation existed between the pretreatment PRA and changes in MBP after magnesium supplementation in EH (r=-0.65, p<0.01), and there was a significant positive correlation between changes in PATPI and changes in MBP as a whole (r=0.41, p<0.05). These results support the view that oral magnesium supplementation is a useful approach to treatment of patients with uncomplicated essential hypertension, especially those with high plasma renin activity. It appears that magnesium suppresses circulating Na⁺, K⁺-ATPase inhibitory activity to attenuate vascular tone, and thereby reduces blood pressure in EH.

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We investigated loss of the nocturnal decline in blood pressure (BP) and its mechanism in diabetes mellitus with autonomic neuropathy (ANP). BP was measured every 30min using ambulatory BP recorders in 52 diabetic patients and 11 nondiabetic controls, As an index of autonomic nervous dysfunction, CV_RR (the coefficient of variation of the R-R interval on ECGs) and diastolic blood pressure response on standing were measured. Plasma volume (PV) was measured with RISA. The difference between daytime mean BP (09: 00 to 13: 00) and nighttime mean BP (01: 00 to 05: 00) was analyzed. The normal control group showed a significant reduction in mean BP during the nighttime (-12.8±7.5mmHg) as compared with the DM group (-3.3±8.6mmHg, p<0.001). The diabetic patients with loss of the nocturnal decline in blood pressure showed autonomic nervous dysfunction and increased PV. In conclusion, the nocturnal elevation of blood pressure might result from an imbalance between reduced tone of sympathetic and parasympathetic functions in addition to the postural effect and increased plasma volume present in diabetic patients.

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The importance of realistic data regarding microvascular geometry for the understanding of oxygen transport to tissue cannot be underestimated. The purpose of the present investigation was therefore to determine the pattern of capillarization in rat myocardium. The histochemical method used in this study was novel in that it allowed for the discrimination of arteriolar capillary (AC) and venular capillary (VC) regions on the basis of color. Our preeminent finding was that systematic differences exist in microvascular geometry from arteriolar to venular capillary regions in normal rat myocardium. Specifically, VC regions are characterized by greater capillary density; more uniform capillary spacing; shorter segment lengths; and increased capillary diameter. These differences translate to significantly greater capillary length, surface and volume densities on the venular side of the capillary bed. In the face of lower PO₂ values towards venules, this distinctive geometry would serve to provide advantageous geometric conditions for oxygen diffusion.

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Effects of denopamine with or without diltiazem on the ischemic heart were investigated in anesthetized open-chest dogs. Partial occlusion of the left circumflex coronary artery (LCX) produced significant decreases in LCX flow and regional myocardial segment shortening rate (%SS) in the LCX-perfused area, and a significant increase in left ventricular enddiastolic pressure (LVEDP). Heart rate (HR) and mean aortic pressure (mAoP) were not altered, but aortic flow (AoF), positive first derivative of left ventricular pressure ((+)LVdP/dt), stroke volume (SV), stroke work index (SWI) and double product showed a tendency to decrease. Total peripheral vascular resistance (TPR) tended to increase. During coronary stenosis, saline infusion (vehicle group) did not change any parameter, but diltiazem infusion (diltiazem group) decreased HR, mAoP, TPR and double product and increased SV and SWI. Under these conditions, denopamine infusion produced increases in HR, mAoP, AoF, (+)LVdP/dt and double product and decreases in LVEDP and TPR in both groups. %SS in the left anterior descending coronary artery-perfused area was increased, but %SS in the LCX-perfused area was slightly decreased in both groups. SV and SWI were decreased by denopamine infusion in the vehicle group, while they were increased in the diltiazem group. Differences in changes in SV and SWI between the groups were statistically significant. Results suggest that combined treatment of denopamine and diltiazem may exert an advantage in alleviation of heart failure due to coronary stenosis.

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In order to determine the effect of adenosine triphosphate (ATP) and adenosine in cardioplegic solutions, a comparative study has been undertaken in isolated guinea pig hearts using the Langendorf perfusion technique as a model of cardiopulmonary bypass.
The hearts (n=10 in each group) previously being perfused by Krebs-Henseleit solution, were arrested by one of the following cardioplegic solutions: 1) Potassium 20mM/L (Plegisol), 2) Potassium 20mM/L+ATP 10mM/L, 3) Adenosine 10mM/L, 4) Adenosine 10mM/L+ATP 10mM/L. After 45min of hypothermic ischemia, postischemic recovery of heart rate, ventricular contractility, heart work and postischemic changes in tissue enzymes (LDH, SGOT, SGPT) were com-pared among the 4 different cardioplegic solutions. Arrest time and number of arrest beats were also recorded and compared among the groups.
Although similar beneficial results on postischemic recovery were achieved with adenosine cardioplegia and with ATP supplemented potassium cardioplegia, ATP supplemented adenosine cardioplegia did not show any beneficial effects on postischemic recovery.

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The antiarrhythmic effects of a new antiarrhythmic agent, SD-3212, (-)-(S)-3, 4-Dihydro-2-[5-methoxy-2-[3-[N-methyl-N-[2-[(3, 4-methylene dioxy)phenoxy]ethyl]amino]propoxy]phenyl]-4-methyl-3-oxo-2H-1, 4-benzothiazine hydrogen fumarate, were investigated using canine models of ventricular arrhythmias, i.e. spontaneously occurring digitalis-, two-stage coronary ligation- and adrenaline-induced arrhythmias. SD-3212 suppressed adrenaline-induced arrhythmia and showed some antiarrhythmic effect on digitalis- and 48hr coronary ligation-arrhythmias. These results indicate that SD-3212 has antiarrhythmic effects common among class IV antiarrhythmic drugs and also has additional efficacy common among class I antiarrhythmic drugs, thus when considering the level of experimental arrhythmias it somewhat resembles propafenone. It may therefore become a clinically useful antiarrhythmic drug among typical class I or class IV antiarrhythmic drugs.

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Hibernating myocardium is an uncommon clinical state involving persistently impaired myocardial function. A 61-year-old man was admitted because of vasospastic angina. Coronary angiography revealed coronary artery dissection in the midportion of the right coronary artery, and segmental vasoconstriction was evoked by acetylcholine. In this patient, hibernating myocardium in the dissected region was clearly demonstrated by dipyridamole thallium-201 imaging. This report describes the first documented case of hibernating myocardium associated with coronary artery dissection, and the usefulness of dipyridamole thallium-201 imaging in the assessment of this state. Coronary artery spasm might be relevant to the etiology of coronary artery dissection.

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A 13-year-old boy with severe coronary stenosis due to Kawasaki disease underwent percutaneous transluminal coronary angioplasty (PTCA). The guide wire and the balloon catheter easily passed through the stenosis in the left anterior descending artery. However, effective dilatation could not be achieved even when the balloon size was increased to 2.5mm in diameter. We discontinued further inflation of the balloon because serious resistance was encountered on withdrawal of the balloon catheter. In patients with Kawasaki disease, the value of PTCA as a treatment for coronary stenosis is questionable.

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We observed 2 cases of repeated episodes of syncope after alcohol ingestion. Both patients were light drinkers and had carotid sinus hypersensitivity. In both cases, alcohol loading tests repeatedly induced sinus bradycardia and hypotension 1.0-1.5 hours after drinking alcohol. Atropine was effective in improving symptoms. A loading test using a glucose solution of equivalent osmolarity and volume was negative. Acute alcohol ingestion usually increases heart rate with variable effects on blood pressure. However, our 2 cases exhibited unusual alcoholinduced sinus bradycardia and hypotension, suggesting a paradoxical increase in parasympathetic activity and/or decrease in sympathetic activity.

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