To distinguish patients with bundle branch block (BBB) and sustained ventricular tachycardia (s-VT) from patients with BBB but without s-VT, a frequency analysis of the QRS complex was performed in 71 patients. Frequency analysis of the QRS complex of patients with left bundle branch block (LBBB) showed that patients with s-VT had significantly larger areas and area ratios between 50 and 100 Hz in the X lead than patients without s-VT (area: -0.905±0.231 vs -1.195±0.286. area ratio: -0.783±0.230 vs -1.125±0.310; P<0.05). The area and area ratios from 100 to 200 Hz in the Z lead were also larger in patients with s-VT. The highest predictive accuracy using the area ratio from 50 to 100 Hz in the X lead was 86%, with a sensitivity and specificity of 83% and 88%, respectively. In cases with LBBB, time domain analysis showed no significant difference between patients with s-VT and those without s-VT. Frequency analysis of the QRS complex may be useful for distinguishing LBBB patients with s-VT from those without s-VT.

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To determine the effect of recent advances in medical management on the survival of patients with dilated cardiomyopathy (DCM), 103 patients with DCM were studied. The subjects were divided into 3 groups based upon the time of initial medical treatment at our institute: Group I, between 1976 and 1981, 20 patients; Group II, between 1982 and 1985, 27 patients; and Group III, between 1986 and 1991, 56 patients. The clinical, Holter electrocardiographic and echocardiographic findings, the pharmacologic treatments used, and the clinical outcomes for the 3 groups of patients were compared. During the follow-up period, which averaged 27 months, 31 deaths related to cardiac disease occurred. The 4 year survival rate was 76% in Group III, 49% in Group II and 35% in Group I; the difference in survival rate between Groups I and III was significant (p<0.01). At the initial evaluation, no differences were found among the 3 groups in the incidences of advanced heart failure (NYHA functional class III or IV), atrial fibrillation or complex ventricular arrhythmias. Neither diastolic blood pressure nor heart rate differed among the 3 groups, but Group III patients were older and had significantly higher systolic blood pressures than Group I patients (p<0.05, for both comparisons). There were no differences among the 3 groups in % fractional shortening, left ventricular end-systolic wall stress or left ventricular wall thickness, but left ventricular dimensions were significantly smaller in Group III than in Group I (p<0.05). Digitalis and/or diuretic agents were administered to all of the patients of Groups I and II and to most of the patients of Group III. There were no differences among the 3 groups in the number of patients who received antiarrhythmics or anticoagulants, but vasodilators and β-blockers were used more frequently in Group III than in Groups I and II (p<0.01 for each comparison). In conclusion, the prognosis of DCM has improved, and various factors, including recent advances in pharmacologic treatments, have contributed to the prolongation of life for patients with DCM.

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We assessed the usefulness of dipyridamole radionuclide ventriculography for detecting significant coronary artery stenosis in 89 patients who were undergoing cardiac catheterization. Radionuclide ventriculography was performed before and after the infusion of dipyridamole (0.56 mg/kg). The end-diastolic regions of interest of the left ventricle were divided into 5 sectors for calculation of the regional ejection fractions. Results were considered to be positive when the regional ejection fraction decreased by more than 5% after the infusion of dipyridamole. The presence of significant coronary artery stenosis ( >75%) was demonstrated by arteriography in 49 patients and was absent in 40 patients. A decrease in the regional ejection fraction greater than 5% was observed in 41 (84%) of the 49 patients with significant coronary artery stenosis and in 2 of the 40 without significant coronary stenosis. The sensitivity and specificity of this method for detecting significant coronary artery stenosis were 84% and 95%, respectively. We conclude that a decrease in the radionuclide-determined regional ejection fraction after the infusion of dipyridamole reflects left ventricular dysfunction and is a sensitive and specific indicator of significant coronary artery stenosis.

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This study assesses the effects of early and late reperfusion of the infarct-related coronary artery and collateral circulation developed after infarction on left ventricular morphology and function in 22 patients with a first acute anterior myocardial infarction and without long-standing preinfarction angina. The patients were categorized into 4 groups: group A-5 patients with successful re-perfusion within 6 h after the onset of infarction: group B-6 patients with late patency of the infarct-related coronary artery; group C-6 patients without re-canalization of the infarct-related coronary artery who had good collateral circulation (collateral index (CI)=2 or 3); and group D-5 patients without re-canalization who had either poor or no collateral circulation (CI=0 or 1). The left ventricular size and function were evaluated by means of contrast left ventriculography during the chronic stage of infarction. The left ventricular global and regional functions were preserved better (p<0.05) in group A than in the other three groups. Although there was no difference in regional wall motion of the infarct area among groups B, C and D, the ejection fraction was greater (p<0.05) and the percentage perimetric circumference was smaller (p<0.05) in groups B and C than in group D. Among the 4 groups, the left ventricular end-diastolic volume index tended to be greater in group D. Thus, these results suggest that blood supply to the infarct area is essential for the preservation of left ventricular size and function regardless of the timing and route.

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To estimate the size of myocardial infarction, serum troponin T concentration was measured in 34 patients with acute myocardial infarction. Left ventriculography, 2-dimensional echocardiography and resting ^20lthallium myocardial single photon emission computed tomography (SPECT) were performed about 4 weeks after the onset of myocardial infarction and used for correlation with the late serum troponin T peak concentration which occurred on the 3rd to 5th day after onset. Both left ventricular ejection fraction (LVEF) obtained from left ventriculography and wall motion index (WMI) obtained from 2-dimension-al echocardiography were inversely related to late troponin T peak value (LVEF: r=-0.68, p<0.001, WMI: r=-0.70, p<0.001). Extent score (ES) and severity score (SS), which were estimated from the initial resting ^20lthallium SPECT image, showed excellent linear correlations with late troponin T peak concentrations (ES: r=0.77, p<0.001, SS: r=0.66, p<0.001). This correlation was present both in patients with an early troponin T peak on day 1 (group A-16 patients) and in those without an early peak (group B-10 patients). Thus, late troponin T peak concentration can be used to predict infarct size regardless of the kinetics of its appearance in serum.

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Eighty-three children were monitored by Holter electrocardiography for ventricular premature contraction (VPC), and the relationship between the preceding RR interval and the coupling interval was plotted using a two-dimensional RR interval plotting method. With this method, the slope (a) and standard deviation (SD) of the linear regression (Y=aX+b) were determined. These parameters were used to classify the patients into one of two types: a fixed type (SD<40 msec, a<0.2) and an unfixed type. The unfixed type was further divided into four subtypes, based on the plotted morphology: scattered, dependent, biphasic, and intermediate. The relationships between the VPC origin, organic heart disease, ventricular tachycardia (VT) and parasystole were investigated in the five types. The fixed and dependent types comprised significantly greater proportions of the subjects with VPC of right ventricular origin than of subjects with VPC of left ventricular origin (fixed: 31/59 right VPC vs 4/24 left VPC, p<0.005; de-pendent: 13/59 vs 1124, p<0.05). On the other hand, comparatively very few subjects of the scattered type showed right VPC (4/59 vs 18124, p<0.005). Finally, the biphasic and intermediate types were distributed fairly equally among the subjects with VPCs of right and left ventricular origin (biphasic: 5/59 vs 0124, p=0.31, intermediate: 6/59 vs 1124, p=0.67). Organic heart disease was present in 13 subjects (15.7% of total subjects), seven of whom were of the fixed type with right ventricular origin (22.6% of subjects of this type). VT was observed in 34 subjects, but was rare in the scattered type (2/22 subject, 9.1%). In the remaining types, VT was observed in about half of the subjects. Of the 14 subjects with exercise-induced VT, 6 were of the dependent type and comprised 42.9% of that type. All parasystole cases were of the scattered type, and most were of left ventricular origin (p<0.01). These results suggest that the correlation between VPC classification by the two-dimensional RR interval plotting method and the characteristics of VPC origin, organic heart disease, VT and parasystole may have useful clinical applications.

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The purpose of this study was to determine the clincal predictors of active infective endocarditis in 45 cases we treated between January 1971 and August 1991 (30 native valve endocarditis (NVE) and 15 prosthetic valve endocarditis (PVE). The indication of surgery in 45 patients was progressive congestive heart failure (CHF), septicemia and systemic embolization. The aortic valve was involved in 24 (53%) of 45 patients (13 of 30 NVE and 11 of 15 PVE) and there was significantly higher early mortality in aortic PVE (36%) than in aortic NVE (8%). The 9 patients with severe cardiac failure (NYHA Class V) before surgery were associated with a significantly higher incidence of early mortality (5/9=56%) than those in Class III (2/14= 14%) and Class IV (3/18= 17%). We concluded that aortic valve infection is more prevalent than mitral valve infection and is more often associated with staphylococcus infection, including abscess formation. Early surgical intervention should be performed despite the risk of cardiac failure and extensive infection.

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Dual-tracer imaging of the heart with ¹²⁵I-metaiodobenzylguanicline (MIBG) and ²⁰¹Tl can simultaneously demonstrate the distribution of sympathetic nerve endings and the underlying myocardial perfusion. A quantitative dual-tracer autoradiographic study with ²⁰¹Tl and 1251-MIBG was performed to investigate changes in the distribution of cardiac sympathetic innervation with the progression of cardiomyopathy in BIO 14.6 hamsters. The distribution of ²⁰¹Tl was uniform in control hamsters and BIO 14.6 hamsters at all stages of cardiomyopathy. In contrast, a reduction in MIBG accumulation occurred in the endocardial region of the left ventricular free wall and the left ventricular aspect of the interventricular septurn in BIO 14.6 hamsters at 3 and 8 months of age. Thus, there was an uncoupling of the left ventricular distribution of ²⁰¹T1 and ¹²⁵I-MIBG in BIO 14.6 hamsters. In addition, interstitial fibrosis was increased in the interventricular septum, the subendocardial region of the left ventricular free wall, and the right ventricular wall, which were the sites of reduced MIBG accumulation. This study shows that dual myocardial imaging with MIBG and ²⁰¹Tl may be useful for investigating patients with cardiomyopathy.

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To investigate the role of renal sympathetic nerve activity (RSNA) under developing and established hypertension, renal function was studied in chronically renal-denervated and sham-operated male spontaneously hypertensive rats (SHR) and control Wistar Kyoto rats (WKY) at 8 (early hypertensive) and 22 (established hypertensive) weeks of age. To further characterize the renal pressure-natriuresis-diuresis relationship in SHR, renal perfusion pressure (RPP) was reduced by aortic constriction to the level seen in age-matched WKY and the same studies were repeated. After denervation, urinary sodium excretion (U_NaV), fractional excretion of sodium (FEN.) and urine flow (UF) were increased in 8-week-old SHR (p<0.01). With the exceptions of U_NaV and FE_Na. in denervated 8-week-old SHR, renal cortical blood flow, glomerular filtration rate, UF, U_NaV and FE_Na decreased with the reduction of RPP in all of the SHR groups. These results suggest that RSNA significantly influences renal sodium and fluid handling, thus contributing to the shifting of the arterial pressure-renal sodium excretion curve to the right along the pressure axis and/or to an increase in the steepness of the relationship in 8-week-old SHR. There appeared to be a marked difference in renal sodium handling between 8-and 22-week-old SHR.

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The use of propranolol is generally contraindicated in patients with congestive heart failure. However, we successfully used a continuous high-dose infusion of propranolol, in combination with the use of extracorporeal life support (ECLS) and intra-aortic balloon pumping (IABP), to treat refractory life-threatening ventricular tachycardia in a patient with postoperative congestive heart failure. The early combined use of ECLS and IABP before irreversible myocardial damage contributed to the successful outcome.

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