New index of cardiac contractility during stress testing with treadmill.

Experimental demonstration that the external phonocardiogram is similar to the third derivative (rate of acceleration) of LV pressure, and that catecholamines cause a similar increase of the early systolic wave of the first derivative of LV pressure and of S1 prompted a study of the first sound during stress testing. Following a previous study with different types of ergometers, the present investigation was based on records of 10 normal, young volunteers, taken during treadmill exercise while a phonocardiogram was recorded at the apex. The first heart sound increased in all of them averaging an eightfold increase during maximal stress. Comparison of the changes in amplitude of S1 with changes of heart rate, blood pressure, and cardiac output revealed that the first showed the most constant proportional increase while sometimes one or the other parameter showed only a moderate change. The possible causes of this apparent lack of reaction is discussed. The importance of the first sound as an index of contractility is stressed, and the suggestion of a routine study of this index in cardiac patients submitted to stress tests is advanced.

Transmission delays of different portions of the arterial pulse. A comparison between the indirect aortic and carotid pulse tracings.

The transmission delays of the upstroke and incisura of the arterial pulse were measured in 128 normal subjects, divided in three groups of increasing age, by comparing the timing of the indirect aortic arch pulse (recorded at the suprasternal notch) (SSN) and the indirect, right carotid tracing (CAR). In the total group, the mean delay of the upstroke was 24.4 msec while the mean delay of the incisura was 19 msec (P less than 0.005). This difference was maximal in the oldest age group and became non significant in the group of children under 12. At slow heart rate, this difference was greater than at a more rapid heart rate. The left ventricular ejection times (LVET), measured on the two pulses, showed a very close correlation (r = 0.96) but the LVET was significantly longer in the SSN tracing, especially in the older subjects. These data reveal that the incisura of the arterial pulse travels more rapidly than the upstroke, especially in older patients and at lower heart rates. The most likely explanation of this fact resides in the frequency-dependent influence of vascular reflections, which is more important with increasing age and slower heart rate. Thus, the transmission velocity along the arterial wall is higher for the higher harmonics of the pulse wave (incisura) than for the lower harmonics (upstroke).

Abnormal left ventricular contraction revealed by impedance cardiograms and arterial tracings in bundle branch blocks and old myocardial infarcts.

Following the observation of an unusual pattern of the first derivative of the impedance cardiogram in cases of bundle branch block, a systematic study was performed both in normal controls and clinical cases. This graphic study was supplemented by the simultaneous recording of the first derivative of an arterial tracing, preferably the indirect aortic pulse at the suprasternal notch. These studies were performed in 70 subjects: 30 normal subjects, 14 cases of right bundle branch block, 14 cases of left bundle branch block, and 12 cases of old infarcts. Out of 30 normal subjects, only 2 old persons showed splintering of the main systolic wave. Both right and left bundle branch blocks had in common either a splitting of this wave in 2 peaks or multiple splintering; however, 4 cases in each type of bundle branch block had a normal pattern. Among old infarcts, 7 had a splitting, 3 had multiple splitting, and 2 had a normal pattern. The derivative of the arterial tracings showed a remarkable similarity with that of the impedance cardiogram, revealing that abnormal left ventricular ejection (dyssynergy) was present in all 3 types of lesion. The first derivative of the impedance cardiogram was often more typical than that of the arterial tracings, because it had fewer secondary vibrations or artifacts. Thus, the former seems more sensitive to diagnosing left ventricular abnormalities of contraction, even when the electrocardiogram is normal.

The pulmonary component of the second heart sound in acquired aortic stenosis.

The amplitude of the pulmonic component of the second sound in aortic stenosis was studied in 49 patients with this lesion. As controls, 50 normal subjects were also studied. Both groups were investigated by phonocardiography, apex cardiography and arterial tracings. Nineteen patients with aortic stenosis and four subjects without it were also studied by cardiac catheterization and angiography. The amplitudes of the two components of the second sound were compared, and the ratio of each with the amplitude of the first sound was determined. The ratios of both the aortic and the pulmonic component to that of the first sound were decreased in aortic stenosis, and the decrease of the pulmonic component was comparable to that of the aortic component. These findings could be related to prolongation of the isovolumic relaxation period of both ventricles caused by an influence of the left ventricle on the right, most likely due to functional changes of the interventricular septum.

Changes of cardiac output caused by aging: an impedance cardiographic study.

The various parameters of cardiac output were studied in 132 healthy subjects from 20 to 89 years of age by impedance cardiography. This noninvasive method supplied data that were similar to those found by others by dye dilution methods. All parameters of cardiac output decrease with age. However, we found a difference between the two sexes in the rate of decrease of the cardiac index: women had a more marked drop at an earlier age and then a steady course, while men had a progressive decrease from the youngest to the oldest group.

The second heart sound in old age.

The second heart sound was studied by phonocardiography and carotid tracings in 103 elderly subjects without overt evidence of heart disease. Their ages ranged from 60 to 99 years. A normal type of splitting was found in 55.3%, and a single sound in 41.7%. The difference between these percentages and those found in 60 normal younger persons was not significant. Thus, a single second sound should not be considered a typical finding in old age. However, a reverse type of splitting, noted in only 3 patients, should be regarded as evidence of severe latent heart disease.

Correlates of the echocardiographic waves of the mitral valve in normal subjects of various ages.

A cardiographic study was performed on 71 subjects including 14 children, 42 young and middle-aged adults, and 15 old persons without evidence of heart disease. The echocardiogram of the mitral valve was recorded in the A mode by an analog method and was compared with the electrocardiogram, phonocardiogram, apex cardiogram, and carotid and jugular tracings, simultaneously obtained. The intervals between the various waves recorded by these methods were measured and the results were compared with those reported in the literature. A comparison of the duration of the intervals in the various age groups showed statistically significant differences. In particular, the intervals between the second heart sound and the peak of the E-wave and the E-F intervals in the echogram were longer in adults than in children and also longer in old persons than in younger adults. This important age difference should always be taken into account before attributing any echocardiographic deviations to disease.