Normal ranges of 32 parameters in vectorcardiography were determined in 200 healthy infants and children. The subjects were divided into 5 groups and results were compared in each group. Significant differences were found in 11 parameters. The differences were associated with a physiologically prominent right ventricular load in younger age groups. Therefore, age should be considered in evaluation of vectorcardiography.

View full abstract

The dipolarity of the body surface potential distribution and the locus of the main dipole were estimated mathematically at 2 msec intervals in 27 normal men. The nondipolar content showed time-dependent fluctuation during the QRS. It increased sharply at early and later phases of the QRS. The main dipole moved smoothly within the actual cardiac region and was inscribed in a clockwise direction in most cases. The nondipolar content during the ST-T period was smaller and with less fluctuation than that during the QRS. The main dipole during the T wave moved less than 2cm near the center of the heart. These results indicated that although a fairly large percentage of the body surface potential could be represented by a single moving dipole, the nondipolar content was larger during initial and late phases of the QRS. It was also suggested that the ventricular repolarization process can be better approximated by a single fixed dipole in normal men.

View full abstract

We developed a new indirect method for the measurement of sinoatrial conduction time (SACT) and the sinus node return cycle (SRC) with a transvenous catheter technique. Two early premature stimuli, at intervals 50 msec longer than the effective refractory period (ERP), were given to the right atrium. These early stimuli were followed by eight constant stimuli. The interval of the constant stimuli was a little shorter than the basic cycle length (BCL). The return cycle A₁A_r was measured and plotted on the abscissa; the next interval A_rA₃, was measured and plotted on the ordinate. This was called the "base point". A new stimulus, A₂, was then added to the train of stimulations, first at a point simultaneous with Ar. It was then shifted toward the last constant stimulus at 10-20 msec intervals until A₂ met the ERP. The relationship between A₁A₂ and A₂A₃ was obtained by the repetition of the procedures with various A₁A₂ intervals. It had two zones, compensatory and non-compensatory. We postulate that the atriosinus conduction time of the last of the eight stimuli was equal to that of A₂ when the stimulus A₂ first captured and reset the sinus nodal pacemaker cells, as indicated by the transition point of the two zones. Based on this supposition, SACT and SRC could be measured as the intervals from the base point to the transition point and from the transition point to the eighth stimulus, respectively.

View full abstract

Analysis of beat to beat changes in left ventricular (LV) ejection time during cardiac pacing was utilized to assess the atrial contribution to ventricular filling in 30 consecutive patients undergoing diagnostic cardiac catheterization. The group consisted of 9 normal subjects, 18 with coronary artery disease and 3 with congestive cardiomyopathy. The recordings of aortic pressure were made during atrial pacing and ventricular pacing at a rate 5 to 10 beats/min above each individual's sinus rhythm. During ventricular pacing, LV ejection time was the longest when an atrial contraction preceded a ventricularly paced beat by a physiologic interval and was approximately similar to that obtained during atrial pacing (maxET). When the atrial systole occurred with or followed the ventricularly paced contraction, LV ejection time was decreased (minET). Since maxET occurred in the presence of an effective atrial contraction to ventricular filling and minET in the absence of this contraction, the atrial contribution to ventricular filling was calculated as (maxET-minET)/maxET×100(%). LV volumes at end-systole (V1), before atrial contraction (V₂) and at end-diastole (V₃) were obtained according to the area-length method by tracing the silhouette of left ventriculograms using a computer system. The atrial contribution was calculated from LV volumes using the formula (V₃-V₂)/(V₃-V₁)×100(%). There was a good correlation (r=0.88) between the atrial contributions calculated from LV ejection times and those calculated from LV volumes. In the patients with coronary artery disease and with congestive cardiomyopathy, the atrial contribution was significantly greater than in the normal subjects. The measurement of LV ejection time during ventricular pacing may be a clinically useful screening procedure to identify patients in whom physiologic pacing may be indicated.

View full abstract

An hydraulic formula for the estimation of cardiac output independent of the geometric status of the left ventricle was studied by comparing the predictions based upon echographic and catheterization data with the results of the standard Fick principle method for cardiac output. The formula tested specifies cardiac output as Q=(1/21) RAT², where Q is the cardiac output in ml, R is the heart rate, A is the mitral valve area in cm² and T is the diastolic filling period in seconds per minute. Cardiac output estimated by this equation corresponds with cardiac output as determined by the Fick principle method at a level characterized by a correlation coefficient of r=0.92 and a standard error of SE=0.15L/min for N=26. The results suggest that the new expression may be useful for estimating cardiac output from echographic data.

View full abstract

We developed a "dual-frame image-freezing unit", which enables acquisition of two stop-frame images of the two-dimensional echocardiogram at different points within one cardiac cycle. We assessed the clinical usefulness of this unit by estimating the left ventricular ejection fraction with apical biplane two-dimensional echocardiography in 25 patients who underwent left ventricular biplane cineangiography. The unit functioned successfully in all instances. It was much easier to obtain the left ventricular enddiastolic and end-systolic echocardiographic images than to obtain such images using conventional videotape play-back. The quality of the images obtained by this unit was better than those obtained from videotape play-back. The echocardiographic estimates of the left ventricular ejection fraction showed an excellent correlation with estimates obtained by contrast left ventricular cineangiography. We conclude that this dual-frame image-freezing unit can be satisfactorily applied for the assessment of the left ventricular ejection fraction by two-dimensional echocardiography.

View full abstract

Twenty-six patients with idiopathic dilated cardiomyopathy (DCM) underwent thallium-201 myocardial scintigraphy. Nine patients (group A) showed a perfusion defect in the interventricular septum (IVS) and 7 patients (group B) showed a defect in the left ventricular posterior wall (LVPW). Hemodynamic responses and catecholamine levels were compared between 16 patients (DCM group) and 6 control subjects (control group) following dopamine infusion (6μg/Kg/min). The end-diastolic thickness of the IVS and LVPW, and the percentage wall thickening were assessed by echocardiography.
Plasma dopamine and norepinephrine concentrations in the DCM group were not different from those of the control group at rest. During the dopamine infusion, however, norepinephrine increased only in the control group. There were significant differences in the thickness of the IVS among the 3 groups [7.3±1.4mm for group A (p<0.001 vs control and p<0.05 vs group B), 8.9±1.5mm for group B (p<0.01 vs control), 10.2±1.5mm for the control group]. The percentage thickening of the IVS increased during the dopamine infusion in group B only and the thickening of the LVPW increased in group A only. Thus, in the myocardium of DCM patients with thallium perfusion defects, the degree of thickening did not change during dopamine infusion, but in the myocardium of DCM patients with normal thallium uptake the percentage thickening increased more than in the control group.

View full abstract

Fifteen consecutive adult patients with uncomplicated atrial septal defects (ASD) underwent echocardiographic examinations both before and 3-8 days (mean 7 days) after surgery to study the early postoperative changes in cardiac dimensions and interventricular septal motion. Echocardiographic analyses included patterns of interventricular septal motion, right and left ventricular dimensions at end-diastole (RVDd & LVDd), aortic root dimension at end-diastole (ARDd) and left atrial dimension at end-systole (LADs). The results showed that the septal motion was abnormal in 87% (13/15) before and 40% (6/15) after operation. RVDd decreased from 36±7mm to 27±7mm (p<0.01) while LVDd increased from 33±6mm to 39±4mm (p<0.01). There were no significant changes in LADs and ARDd after surgery. These observations suggest that in patients with ASD the ventricular dimensions and patterns of interventricular septal motion are changed significantly shortly after surgical epair.

View full abstract

Cardiac manifestations in 321 patients on chronic hemodialysis (dialysis duration of from 0.1 to 11.3 years) were examined with non-invasive technique. In contrast to the previous assumption that cardiac dilatation and pericardial effusion are common in patients on chronic hemodialysis, interventricular septal hypertrophy (51.3%) and left ventricular posterior wall hypertrophy (47.1%) on echocardiography and left ventricular hypertrophy (47.0%) on ECG were the most frequent abnormalities in these patients. Although premature beats on routine ECG were found in a limited number of patients (4.7%), ventricular premature beats were recognized in 45.7% and high grade arrhythmias in 27.2% of 92 patients examined with 24-hour Holter ECG monitoring. There were no high grade arrhythmias and the frequency of ventricular premature beats was 19.4% in 31 age-matched healthy subjects studied. Furthermore, the PQ interval was progressively prolonged in relation to the duration of hemodialysis. This finding may suggest that longterm hemodialysis is associated with disturbances of the conduction system.
These results indicate that myocardial hypertrophy and high grade arrhythmias are the prominent findings in uremic patients maintained on hemodialysis. We consider that such high grade arrhythmias could be responsible for a high incidence of cardiac death in these patients.

View full abstract

T1-201 myocardial imaging and Tc-99m-HSA gated equilibrium ventriculography were performed in 1 infant and 11 children between 2 months old and 12 years old with myocarditis. The time of first evaluation was between 1 week and 13 months after the onset. Their clinical manifestations were congestive heart failure in 2 patients, pericardial effusion in 2 patients, syncope in 1 patient, convulsions in 1 patient and palpitations in 7 patients. Significant elevation of virus antibody titer was demonstrated in 6 patients. A perfusion defect was observed with T1-201 imaging in 9 of 12 patients with myocarditis. A right ventricular image was observed in 5 patients. A reduced LVEF was present in 4 patients and a reduced RVEF was found in 2 patients. Cardiac catheterization was performed in 8 patients and an endomyocardial biopsy was done in 7. The myocardial specimens revealed postmyocarditic pathological changes upon microscopic evaluation. No coronary artery obstructive or stenotic lesions were observed in these patients. T1-201 myocardial imaging is a useful noninvasive technique for evaluating the cardiac performance and myocardial damage in acute myocarditis and the postmyocarditic state. We conclude that T1-201 uptake of myocardium is dependent upon both regional coronary perfusion and the activity of myocardial cells in patients with myocarditis and in the postmyocarditic state.

View full abstract

Right ventricular systolic and diastolic function was studied in patients with ischemic heart disease using equilibrium radionuclide ventriculography. In patients with inferior myocardial infarction and proximal right coronary lesions, the right ventricular ejection fraction (0.43±0.06, n=10, mean±SD) and peak filling rate (1.7±0.4 EDV/sec) were lower than normals (0.57±0.07 and 2.7±0.4 EDV/sec, n=10, p<0.001, respectively). In these patients, the right ventricular time to peak filling rate was longer than in normals (225±36 msec vs 136±45 msec, p<0.001), while the left ventricular ejection fraction remained normal. In patients with inferior myocardial infarction and distal right coronary lesions, the right ventricular ejection fraction, peak filling rate and time to peak filling rate were not different from those in normals. Even in patients with proximal right coronary lesions, the right ventricular ejection fraction was normal unless they had an inferior myocardial infarction. A decreased left ventricular ejection fraction and abnormal motion of the ventricular septum did not affect the right ventricular ejection fraction. The present results suggest that patients with an inferior myocardial infarction and proximal right coronary lesion often develop right ventricular systolic and diastolic dysfunction.

View full abstract

The effects of d1-2-(3'-t-butylamino-2'-hydroxypropylthio)4-(5'-carbamoyl-2'-thienyl) thiazole hydrochloride (S-596) were evaluated in 9 normal volunteers. Exercise echocardiography was performed in the semi-supine position before and 2, 4 and 24 hours after the oral administration of 15mg of S-596. Two hours after administration, resting heart rate was unchanged, compared with control, but systolic blood pressure at rest was slightly decreased (114±6 vs 106±10mmHg, p<0.05). Left ventricular dimensions were unchanged, but shortening fraction was increased in the resting state (30.3±4.6 vs 33.1±4.8%, p<0.05). During exercise on oral S-596, heart rate and systolic blood pressure responses were reduced (127±11 in control vs 108±6 beats/min on S-596, 198±25 vs 168±23mmHg, p<0.001 and 0.05, respectively). Left ventricular enddiastolic dimension was not significantly altered by S-596 compared with the preceding control exercise test; however, end-systolic dimension was significantly larger after beta blockade with S-596 (2.6±0.4 vs 3.0±0.4 cm, p<0.05). Shortening fraction and cardiac output decreased significantly (43.7±3.7 vs 40.0±5.7%, 9.5±1.4 vs 8.4±1.3L/min, p<0.05 and 0.01, respectively). These effects of S-596 were maximal at 2 hours after oral administration with reduced response of heart rate to exercise lasting for 24 hours. Compared with the effects of propranolol (30mg, given orally) in the same subjects, beta-adrenergic blockade during exercise with S596 was equivalent to or greater than that of propranolol.
Thus, S-596 has little, if any, effect on resting left ventricular performance, but demonstrates potent negative chronotropic and inotropic effects during exercise in normal human subjects. Its beta-adrenergic blocking action also has long acting properties, especially its chronotropic effect.

View full abstract

Serum creatinine and routine urinalysis were obtained and glomerular filtration rate estimated in 56 consecutive and hemodynamically stable children with congenital heart disease undergoing cardiac catheterization and angiocardiography, a day prior to, 1 and 7 days following the procedure. None had a history of renal disease. The patients were divided into 2 groups: Group I, 32 patients who received<3ml/Kg of Renagrafin 60 and Group II, 24 patients who received>3ml/Kg. Despite a slight rise of creatinine on the first day, there were no statistically significant changes in serum creatinine or glomelular filtration rate for either group following the procedure. Occult blood was present in the urine of 2 in Group I and 1 in Group II prior to cardiac catheterization; this resolved in all cases after the procedure. Three patients in Group I and 1 in Group II developed transient trace proteinuria following the angiographic procedure. It is concluded that in children with congenital heart disease and normal kidney function, substantial doses of standard contrast medium administered during angiocardiography do not produce any apparent impairment of renal function.

View full abstract

Six intracardiac myxomas and 2 thrombi were subjected to scanning electron microscopy (SEM). Surface morphology of myxomas was distinct from thrombi. The surface of myxoma was either smooth or thrown into projections which had a continuous endothelial lining. This was lacking in thrombi. Cut surface of myxoma revealed the presence of round to polyhedral cells having blunt villi and/or pit-like depressions on their surface in a stroma of fibres, granular material and blood vessels. Thrombi were composed of blood elements enmeshed within fibres. No cells of the type encountered in myxomas were present.

View full abstract

This paper reports several modifications of our previous culture method1) for adult rat heart cells. Mechanical separation of the cells at 12rpm rather than 8rpm doubled the number of beating cells in the final culture medium. A 60% Ficoll-Paque solution was found to be optimal for exclusion of non-muscle cells such as endothelial cells and fibroblasts from the culture, followed by frequent medium exchange to eliminate traces of this reagent from culture medium. However, the presence of some non-muscle cells seemed to exert a positive effect on culture longevity. Eagle's MEM medium containing 20% FBS resulted in maximum (over 50 days) survival of cultures.

View full abstract

The relationships of electrical changes to the time course of reduction in adenosine triphosphate (ATP) content were examined in 41 dogs with coronary artery ligation and 14 control dogs. Twenty dogs with malignant ventricular arrhythmias within 10min of ischemia (VA dogs) were characterized by widening of the composite electrogram duration (147±47msec at 5min). In con-trast, the composite electrogram duration was narrower (71±12 msec at 5min, p<0.001) in 21 dogs without malignant arrhythmias (non-VA dogs). The degree of ATP reduction in VA dogs was significantly less at 3min (3.11±0.28μmol•g^-1, p<0.05) and at 5min (2.93±0.28μmol•g^-1, p<0.05) than in non-VA dogs (2.76±0.22μmol•g^-1, 2.39±0.44μmol•g^-1, respectively). The width of the electrograms in VA dogs decreased gradually after 10min of ischemia, and it was not significantly different from non-VA dogs by 13min, which coincided with disappearance of a difference in ATP content (2.10±0.34μmol•g^-1 and 2.35±0.23μmol•g^-1 in VA dogs and non-VA dogs biopsied at 10-20min of ischemia). It was concluded that the metabolic deterioration in VA dogs advanced more slowly than that in non-VA dogs within 5min of ischemia and the decrease in the width of the electrogram after 10min did not result from a partial recovery of ischemia.

View full abstract

In a review of 160 cases of hypertrophic cardiomyopathy which underwent hemodynamic studies, 3 cases of apical aneurysm of the left ventricle of unidentifiable etiology were found. Bearing in mind the rarity of apical idiopathic left ventricular aneurysms, the authors believe this association with hypertrophic cardiomyopathy is of some interest and point out the possible pathogenetic mechanisms.

View full abstract