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Biomedical subjects

V Bhargava

Publications and source records attributed to V Bhargava.

At least 19 recordsLinked to original sources
PubMed1992

Diastolic regional wall motion asynchrony in patients with hypertension.

Left ventricular regional wall motion was analyzed from angiographic ventriculograms in 51 subjects, 18 of these served as controls, 10 were hypertensive with coronary artery disease, and 23 had a history of hypertension without coronary artery disease. All normal subjects showed normal synchronous wall motion throughout the cardiac cycle. In 10 patients with coronary artery disease and hypertension at the time of catheterization, the major determinant of regional abnormality was coronary artery lesion (sensitivity = 83%, specificity = 95%). Patients who had a history of hypertension and no ischemic disease, were further subdivided into three groups, 4 who were normotensive, 4 with borderline pressures and 15 hypertensive at the time of cardiac catheterization. All normotensive, 3 of the borderline hypertensive, as well as one hypertensive (without coronary artery disease) patients showed normal wall motion. In one patient with borderline pressure and 14 of 15 hypertensive patients diastolic regional asynchrony was detected. Apical region was most commonly affected in these patients. This suggests the importance of treating hypertension in patients and the possible reversibility of abnormal wall motion with treatment.

Adult↗
PubMed1992

Heart size and maximal cardiac output are limited by the pericardium.

We tested the hypothesis that the pericardium, by restricting heart size, limits maximal cardiac output and oxygen consumption. We studied 15 pigs. Five underwent maximal treadmill running before and 14-21 days after thoracotomy and pericardiectomy; these pigs also received sequential volume infusions to determine end-diastolic pressure-dimension relationships. Five underwent maximal treadmill running before and 14-21 days after thoracotomy (pericardium undisturbed) to determine the effect of thoracotomy on exercise performance. Finally, five underwent thoracotomy, instrumentation, loose closure of the pericardium, and sequential volume infusions to determine the effect of thoracotomy without pericardiectomy on end-diastolic pressure-dimension relationships. Pericardiectomy caused similar increases in maximal cardiac output (29% increase; P = 0.007) and maximal oxygen consumption (31% increase; P = 0.02). These results were associated with increased left ventricular end-diastolic dimension (10% increase; P = 0.01) and an estimated 33% increase in end-diastolic volume. In addition, left ventricular mass was increased by pericardiectomy (18% increase; P < 0.04). Thus the pericardium, by limiting utilization of the Starling mechanism, limits maximal cardiac output, and the limit to cardiorespiratory performance lies not in oxygen utilization, but in oxygen delivery. Furthermore, removal of pericardium is associated with myocardial hypertrophy.

Animals↗
PubMed1992

Digital image analysis of shark gills: modeling of oxygen transfer in the domain of time.

Digital radiographic imaging of blood circulation through leopard shark gills establishes a secondary lamellar transit time of 6.5 s. This duration, combined with estimates of cardiac output and hemoglobin-oxygen affinity, permits novel modeling of gill oxygen transfer in the time domain. The temporal model allows assessment of factors contributing to previously noted discrepancies between physiological and morphometric branchial oxygen conductance estimates. Lamellar transit time for shark blood is 20 times greater than human alveolar transit time, and thus correlates with a slower rate of hemoglobin-oxygen binding and a greater diffusion distance.

Animals↗
PubMed1991

Mucocele-like tumors of the breast. Cytologic findings in two cases.

Mucocele-like tumors of the breast originally were reported by Rosen in 1986 as benign lesions that histologically resembled colloid carcinoma of the breast. The authors document two cases of mucocele-like tumors to illustrate the difficulty in separating these lesions from colloid carcinoma on the basis of fine-needle aspiration biopsy. Cytologically, mucocele-like tumors contained abundant mucin, few clusters, and sheets of regular epithelium that lacked nuclear atypia, and they contained no intact single cells. The authors recommend open surgical biopsy when fine-needle aspiration biopsy findings in such cases are equivocal.

Adult↗
PubMed1991

Pericardial influences on right and left ventricular filling dynamics.

The influence of the pericardium on right and left ventricular filling was studied using two-dimensional and Doppler echocardiography in 14 open-chest dogs. Doppler echo parameters of filling included early (E) and late (A) velocities and their ratio (E/A) for the mitral and tricuspid valves. Right and left ventricular volumes were calculated from orthogonal two-dimensional echocardiographic images. Data were compared at three levels of left ventricular end-diastolic pressure (6 +/- 2, 13 +/- 3, and 21 +/- 4 mm Hg) at matched heart rates before and after pericardiectomy. The instantaneous diastolic pressure gradient was measured in 12 of the dogs. Pericardiectomy resulted in an increase in early mitral velocity, peak early diastolic pressure gradient, and E/A but not early mitral velocity normalized for end-diastolic volume. In contrast, for the tricuspid valve flow, pericardiectomy did not change E but caused a marked increase in A and a decrease in E/A. Right ventricular end-diastolic volumes at matched left ventricular end-diastolic volumes were similar before and after the pericardium was removed. However, removal of the pericardium caused a significant decrease of the slope for the right (86.0 +/- 27.0 x 10(-4) versus 50.0 +/- 19.5 x 10(-4) mm Hg/ml, p less than 0.01), but not left, ventricular ln end-diastolic pressure-volume relation (21.2 +/- 9.2 x 10(-3) versus 21.4 +/- 5.3 x 10(-3) mm Hg/ml, p = NS), and a decrease of the pressure intercept for the left (3.0 +/- 2.0 versus 1.6 +/- 0.9 mm Hg, p less than 0.05), but not right, ventricular ln end-diastolic pressure-volume relation (2.8 +/- 1.4 versus 1.4 +/- 0.8 mm Hg, p = NS). In conclusion, filling of the two ventricles is affected by the pericardium over a wide range of physiological ventricular volumes and pressures. At matched left ventricular end-diastolic volume, pericardiectomy causes a fundamental alteration in right, but not left, ventricular filling.

Animals↗
PubMed1991

Effects of mental exercise in patients with dilated cardiomyopathy and congestive heart failure. An echocardiographic Doppler study.

To assess the effects of mental stress on left ventricular diastolic function in patients with congestive heart failure, nine patients aged 57 +/- 12 years with dilated cardiomyopathy (end-diastolic volume, more than 110 ml/m2; ejection fraction, less than 40%; mean, 28 +/- 8%) and congestive heart failure in New York Heart Association functional class II or III and 14 normal volunteers (mean age, 49 +/- 8 years) were studied during mental arithmetic lasting 10 minutes with echocardiographic Doppler monitoring of transmitral flow velocity. During mental arithmetic, the ratio of peak flow velocity in early versus late diastole (E/A) and deceleration time of early diastole did not change in normal controls. However, E/A increased significantly (from 1.6 +/- 1.5 to 1.9 +/- 1.7; p less than 0.01) and deceleration time markedly decreased (from 156 +/- 49 to 108 +/- 31 msec; p less than 0.001) in patients with congestive heart failure. In 16 postinfarct patients with ejection fraction of less than 40% studied during mental arithmetic with simultaneous hemodynamics and Doppler recordings, good correlations were found between pulmonary wedge pressure and Doppler parameters (wedge pressure versus E/A, r = 0.89; wedge pressure versus deceleration time, r = -0.87). During mental arithmetic, the pulmonary wedge pressure-E/A correlation was weaker (r = 0.67), whereas the correlation between pulmonary wedge pressure and deceleration time was stronger (r = 0.91). The value of 153 msec in deceleration time was the best cutoff point in predicting 12 mm Hg pulmonary wedge pressure, both at rest and during mental arithmetic: the higher the deceleration time, the lower the pulmonary wedge pressure, and vice versa. Among patients with congestive heart failure, five showed normal baseline deceleration time (195 +/- 21 msec; pattern 1), and the remaining four showed a short (less than 153 msec) deceleration time (108 +/- 13 msec; pattern 2). During mental arithmetic, deceleration time markedly decreased to as short as 119 +/- 20 msec in all patients except one with baseline pattern 1. Deceleration time further decreased to 75 +/- 6 msec in all patients with baseline pattern 2. Mental arithmetic induces changes in left ventricular diastolic function in patients with congestive heart failure. Transmitral echocardiographic Doppler provides a simple noninvasive method of estimating and monitoring pulmonary wedge pressure in patients with severe left ventricular dysfunction.

Cardiomyopathy, Dilated↗
PubMed1990

Regional left ventricular wall motion abnormalities in idiopathic dilated cardiomyopathy.

An evaluation and a comparison of left ventricular regional wall motion were performed in 32 patients with idiopathic dilated cardiomyopathy, none of whom had coronary artery diameter stenosis exceeding 20% in any major artery, and 17 control subjects, using frame by frame video intensity analysis of digitized ventriculograms. This technique evaluates the whole cardiac cycle in short overlapping intervals and yields information for systolic and diastolic events, without assumptions regarding the position and orientation of the ventricle. Diastolic regional wall motion abnormalities were found in 31 of 32 patients and systolic abnormalities were present in 16 patients. Asynchronous regions most commonly detected during diastole were anteroapical and apical; they were found in 19 of 32 patients. Regional contraction abnormality was observed in the apical and the anteroapical regions in 6 of 16 patients. Dilatation-induced changes in left ventricular shape exaggerate the phenomenon of higher wall stress at the apex of the normal ventricle. Basal wall motion is thus relatively preserved in dilated cardiomyopathy.

Adult↗
PubMed1990

Detection and quantitation of ischemic left ventricular dysfunction using a new video intensity technique for regional wall motion evaluation.

Eighty patients with ischemic heart disease and 17 normal subjects were evaluated for left ventricular regional wall motion by means of a new method. The wall motion analysis is based on video intensity. This technique uses a temporally sliding analysis to evaluate the cardiac cycle in 100 msec intervals. Presence of coronary artery disease was defined as more than 50% measured diameter stenosis. Wall motion abnormalities in regions perfused by stenotic vessels were most common in early diastole (76%). Sensitivity of this method at rest in patients with coronary artery disease was 79.7% (p less than 0.0001) and overall accuracy was 84.2% (p less than 0.0001). Abnormalities in both systole and diastole were more common in regions perfused by severe lesions (greater than 75%) than in those perfused by moderately stenotic (less than 75%) vessels (p less than 0.05). A comparison of the new method with phase and amplitude analysis was performed in 15 patients and with two-frame analysis in 40 patients. This new method yielded a higher sensitivity than either of the other two methods.

Adult↗
PubMed1990

Left ventricular asynchrony in patients with pulmonary hypertension.

Left ventricular regional wall motion was evaluated in 11 patients with pulmonary hypertension and 18 control subjects. All 11 patients had secondary pulmonary hypertension and less than 20% measured diameter stenosis in any vessel. This study utilizes a video-intensity-based frame-by-frame computerized technique. All pulmonary hypertensive patients showed early diastolic asynchrony in the anterior or apical regions that lasted 100-200 ms. The size of the abnormal area varied from 2 to 20% of the ventricular silhouette. Four patients also showed systolic abnormalities. No abnormalities were detected in the control group. The cause of the asynchrony detected in pulmonary hypertension is probably due to interventricular interaction caused by pressure gradients across the septum.

Adult↗
PubMed1989

Instantaneous transmitral flow using Doppler and M-mode echocardiography: comparison with radionuclide ventriculography.

To improve the accuracy of Doppler echocardiographic indices of left ventricular filling, we derived two indices of instantaneous transmitral flow with the use of Doppler velocities and M-mode echocardiography. These indices were calculated from the product of pulsed Doppler mitral velocities and either the excursion of the anterior mitral leaflet or the separation of both mitral leaflets as measures of the changing mitral orifice area. The derived flow indices and the mitral velocities alone were compared to left ventricular filling as determined by radionuclide ventriculography in 24 patients. When compared as areas under the matched decile divisions of the derived filling sequences by linear regression analysis, the relationship for combined Doppler and M-mode versus radionuclide left ventricular filling was closer to the line of identity (slope = 0.98 and 0.94 using the anterior mitral leaflet and both mitral leaflets, respectively, both p = NS versus the line of identity) than was the relationship for mitral velocities alone versus radionuclide left ventricular filling (slope = 0.74, p less than 0.05 versus the line of identity). The instantaneous mitral volume flow indices more closely resemble the time course and shape of radionuclide left ventricular filling curves than do mitral velocities alone, and the application of these indices should assist the quantitative description by Doppler echocardiography of left ventricular filling.

Aged↗
PubMed1989

Branchial blood flow distribution in the blue shark (Prionace glauca) and the leopard shark (Triakis semifasciata).

Electromagnetic flow (EMF) quantification of total cardiac stroke flow is not feasible for most elasmobranchs because the vascular anatomy precludes probe placement adjacent to the heart and proximal to all afferent branchial arteries (aba). Most previous studies report a fractional cardiac flow, made with the EMF probe placed on the ventral aorta between the innominate arteries and aba 3. Estimation of total cardiac stroke flow from such data requires a flow correction factor obtained by sacrificing the fish, and carrying out a two step in situ/in vitro flow calibration procedure which is based on tenuous assumptions. Ventral aortic blood flow measurements using the EMF techniques were carried out on large blue sharks, and radiographic imaging studies of ventral aortic and branchial blood flow were done on leopard sharks to verify previously estimated fractional cardiac stroke flow correction factors. The innominate flow fraction determined for both species in these studies are similar and agree with previous estimates for elasmobranchs. EMF data for Prionace show 38% of cardiac stroke flow goes to the innominate arteries, 23% into aba 3, 12% into aba 4, and 27% into aba 5. Radiographic analyses with Triakis reveal that 32% of its cardiac stroke volume flows into the innominate arteries which is in agreement with the in situ/in vitro fractional flow estimate (33%).

Animals↗
PubMed1979

Instantaneous transmitral blood flow and anterior mitral leaflet motion in man.

Transmitral blood flow was measured in man by numerical differentiation of left ventricular volume as a function of time in 11 patients undergoing cardiac catheterization. Using this technique, transmitral blood flow may be studied in a variety of pathologic states without the need for surgically introduced flowmeters. Just before left ventriculography, echocardiography of the mitral valve was performed. The pattern of transmitral blood flow was strikingly similar to the diastolic movement of the anterior mitral leaflet. At any equivalent diastolic filling time, the percent of the integrated area beneath the curve inscribed by the diastolic anterior mirtal leaflet echoes closely approximated the percent of stroke volume which had entered the left ventricle. This observation supports the hypothesis that mitral leaflet motion accurately reflects transmitral flow. Consequently, at a given time during diastole, the relative velocity of transmitral flow and the percent of the stroke volume which has entered the left ventricle may be approximated noninvasively from the anterior mitral leaflet echogram.

Adult↗
PubMed1978

Electrophysiologic and hemodynamic effects of verapamin. Correlation with plasma drug concentrations.

Verapamil was administered intravenously to 30 open-chest dogs and the electrophysiologic and hemodynamic effects of the drug were correlated with the corresponding plasma concentrations. At concentrations below 152 ng/ml, verapamil prolonged the A-H interval, abolished ventriculoatrial conduction, but did not significantly change sinus rate, cardiac output, left ventricular dp/dt, of systemic vascular resistance. Concentrations above 200 ng/ml were associated with slowing of the sinus rat, high degree atrioventricular block during atrial pacing, 24% decrease in mean aortic pressure, and decreased cardiac output and left ventricular dp/dt. Sinus arrest, high degree atrioventicular block during sinus rhythm, decreased systemic vascular resistance and increased left ventricular end-diastolic pressure occurred when plasma verapamil concentrations exceeded 400 ng/ml. These results show that plasma verapamil concentrations reliably reflect the electrophysiologic and hemodynamic actions of the drug, and that "therapeutic" drug effects can be achieved at plasma concentrations at which myocardial depressant effects are unlikely.

Animals↗
PubMed1978

Alteration of the left ventricular diastolic pressure-segment length relation produced by the pericardium. Effects of cardiac distension and afterload reduction in conscious dogs.

Left ventricular pressure and segment length were measured in seven conscious chronically instrumented dogs with the pericardium intact and 3-9 days after pericardiectomy. Diastolic pressure-length plots were obtained under control conditions and after acute volume loading followed by sodium nitroprusside infusion. In all dogs with intact pericardium, volume loading displaced the entire diastolic pressure-length curve upwards and sodium nitroprusside shifted it toward control. After pericardiectomy the pressure-segment length data during control, volume loading and sodium nitroprusside fell on a single curve (intercepts and slopes not statistically different); After dextran infusion, intrapericardial pressure rose from control 1.5 +/- 0.7 mm Hg to 8.2 +/- 0.5 mm Hg, and it fell to 4.8 +/- 0.1 mm Hg after nitroprusside. Therefore, in acute cardiac dilatation the pericardium contributed significantly to the increased left ventricular diastolic pressure and to the fall during sodium nitroprusside infusion and appeared responsible for shifts in the diastolic pressure-segment length relation.

Animals↗