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Biomedical subjects

V Bhargava

Publications and source records attributed to V Bhargava.

185 records · Page 11Linked to original sources
PubMedDate not supplied

Pulmonary blood volume: correlation of equilibrium radionuclide and dye-dilution estimates.

In fifteen prospective patients with aortic stenosis undergoing transseptal cardiac catheterization, dye-dilution and count-based estimates of pulmonary blood volume (PBV) were performed. Three radionuclide methods were evaluated. Two were based on electrocardiogram (ECG)-gated imaging of the thorax, where pulmonary counts (PC) were corrected for frame-time, venous radioactivity, and either (1) the number of processed heart beats or (2) the total duration of acquisition. The third method involved ungated frame mode acquisitions, where PC were corrected for the duration of acquisition and the venous activity. PC (per channel element) were derived from manual assignments of the right lung. All methods correlated well with standard dye-dilution techniques (r greater than 0.82), though at greater volumes it was clear that count-based methods underestimated the dye-dilution values. In five acutely instrumented, anesthetized dogs, radionuclide (ungated formula) and dye-dilution estimates of PBV were made during multiple interventions (19 data points). The five control count volumes as well as the 14 separate intervention points correlated well (r greater than 0.89). It is concluded that PC from equilibrium blood pool images reflect PBV and that induced changes in PC can be utilized as a reflection of changes in PBV.

Adult↗
PubMedDate not supplied

A comparison of peak-to-peak pulmonary transit time determined by digital intravenous angiography with standard dye-dilution techniques in anesthetized dogs.

To evaluate the relationship between mean pulmonary transit time and peak-to-peak transit time by digital intravenous angiography six dogs were assessed during either isoproterenol or phenylephrine infusion. Acutely anesthetized dogs were instrumented with catheters in the pulmonary artery, left atrium, and carotid artery. An injection catheter was placed in the inferior vena cava, and contrast injections were made with a power injector (30 cc/second for 1 second of Renografin 76). Peak-to-peak transit times (pulmonary artery-left atrial time) were derived from videodensitometric time-absorption curves. Mean transit time was calculated from the usual optical densitometric analyses of green dye injected first in the pulmonary artery and then in the left atrium (sampled in a carotid artery). Peak-to-peak times averaged 3.6% greater than mean transit time (4.39 +/- 1.76 seconds vs. 4.24 +/- 1.82 seconds, P less than .05), though they correlated well with green dye values (r = .97; y = .97 x +.44). It was concluded that peak-to-peak transit times are excellent approximates of standard dye-dilution mean transit times and may simplify calculations of the pulmonary circulation when videodensitometric or radionuclide techniques are utilized.

Anesthesia↗
PubMedDate not supplied

Automatic analysis of left ventricular ejection fraction using stroke volume images.

The purpose of this study was to analyze, validate, and report on an automatic computer algorithm for analyzing left ventricular ejection fraction and to indicate future applications of the technique to other chambers and more advanced measurements. Thirty-eight patients were studied in the cardiac catheterization laboratory by equilibrium radionuclide ventriculography and concurrent contrast ventriculography. The temporal and spatial behavior of each picture element in a filtered stroke volume image series was monitored throughout the cardiac cycle. Pixels that met specific phase, amplitude, and derivative criteria were assigned to the appropriate chamber. Volume curves were generated from regions of interest for each chamber to enable calculation of the left ventricular ejection fraction. Left ventricular ejection fractions showed a good correlation (r = 0.89) between the two techniques. Ejection fractions ranged between 0.12 and 0.88, showing a wide range of application. It is concluded that automatic analysis of left ventricular ejection fraction is possible using the present algorithm and will be useful in improving the reproducibility and providing more accurate information during exercise protocols, pharmaceutical interventions, and routine clinical studies.

Cardiac Output↗
PubMedDate not supplied

The acute effects of cigarette smoking on left ventricular function.

Cigarette smoking is a major risk factor of coronary artery disease. Frequent repetition of an acute effect on the heart caused by cigarette smoking has been suggested as the etiology because of the increased incidence of myocardial infarction in cigarette smokers which drops to the incidence in non-smokers after cessation of smoking. This study of cardiac patients during cardiac catheterization evaluates the acute effect of the ordinary cigarette, smoked in the individuals own manner, on parameters of cardiac pump and muscle performance. The accuracy of measurements was enhanced by employing high-fidelity pressure signals, signal averaging, and computer analysis of the data. The results of the present study suggest that when cardiac patients smoke 1 cigarette of their own brand in their accustomed manner, no deleterious effects on pump performance, ventricular contraction or relaxation and blood pressure are evident.

Acute Disease↗