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Biomedical subjects

P K Bhat

Publications and source records attributed to P K Bhat.

8 recordsLinked to original sources
PubMed1980

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.

Adult↗
PubMed1977

On the function of the aortic valve and the mechanism of the first and second sounds.

Studies are reported on the exact timing of the aortic component of the second sound in relationship to aortic pressure and flow velocity, and also to aortic valve closure. These studies were performed in animals by means of catheter-tip probes and an electric contact introduced into the aortic valve. They were supplemented by echocardiographic stuides of the aortic valve, and impedance cardiograms in man. Opening of the aortic valve and its relationship to the first heart sound were also studied. It was observed that the second component of the first heart sound grossly coincides with the opening of the aortic valve. The aortic component of the second sound starts a few milliseconds after aortic valve closure. It starts after the incisura of the aortic pressure tracing and the drop of the velocity curve to the zero line; it then increases attaining its maximum at the peak of the rapid rebound of the aortic pressure, which coincides with the trough of the velocity tracing. The final interpretation on the mechanism of the second sound agrees in principle with the studies of Luciani, Wiggers, and Rushmer attributing the sound vibrations to release of the energy stored in the aortic wall, which accelerates the flow and causes deceleration of numerous structures (aortic and valvar) as well as of the blood. Studies of the rate of change of acceleration of pressure confirm this interpretation.

Adolescent↗
PubMed1977

[The high frequency components of the heart sounds in normal subjects (author's transl)].

A technical set up for recording high frequency components of the cardiac vibrations is described. This was based on the use of several amplifiers, taking the third derivative of the displacement tracing, and using a high pass filter with a sharp slope. The tape-recorded high frequency tracing, at 500 Hz, 1000 Hz, or higher, was replayed at slower speed for accurate recording of the high speed signals. A study of the first and second hearts sound at 500 Hz and 1000 Hz was made in 14 young, normal volunteers. The high frequency vibrations of these sounds are analyzed and discussed.

Adult↗
PubMed1976

Incidence of murmurs in the aging heart.

One hundred patients aged 60 or older were studied clinically after excluding those with cardiac enlargement, definite valvular lesions or electrocardiographic (ECG) evidence of left ventricular hypertrophy. In 30 of the the 100 patients a significant systolic murmur was heard on auscultation. Phonocardiograms (PCGs), mitral echograms and pulse tracings were obtained in 28 of these 30 patients (2 had died meanwhile), and the ECGs and chest roentgenograms were reviewed. In 23 PCG patients there was an early or midsystolic murmur, best recorded at the base of the heart and often transmiteed to the apex. Mitral valve echograms and carotid and jugular pulse tracings were normal in all cases. Chest roentgenograms revealed aortic enlargement in 83 percent of the 23 patients. In the elderly with no evidence of organic heart disease, a basal systolic murmur is probably an aortic flow phenomenon caused by either moderate aortic dilatation or minimal fibrotic fusion of one or more commissures of the aortic valve.

Age Factors↗
PubMed1975

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.

Adolescent↗
PubMed1975

Ventricular relaxation and mitral opening time in various ventricular conditions of old age.

This phonocardiographic-echocardiographic study was based on measurement of the interval between the aortic component of the second sound (IIA) and the peak of the E wave of the mitral echogram. The study was performed in 20 cases of left bundle branch block (LBBB), 10 cases of right bundle branch block (RBBB), 10 cases of old myocardial infarct (MI), and 10 cases of systemic hypertension (HY). All patients were above 60 years of age, and their data were compared with those of old persons without evidence of heart disease serving as controls. The IIA-E interval was found markedly prolonged in LBBB, less prolonged in MI and RBBB, and was shortened in HY. A dynamic analysis revealed that this interval results from the isovolumic relaxation period (IRP) of the left ventricle plus the "opening time" of the mitral valve. The changes observed were explained as resulting from a modification of the IRP that should be correlated with a similar modification of the isovolumic contraction time. Myocardial fibrosis would cause prolongation of IRP through structural lesions while hypertension would cause abbreviation of IRP through hormonal effects modifying both contraction and relaxation.

Aged↗