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Biomedical subjects

K B Sagar

Publications and source records attributed to K B Sagar.

65 records · Page 4Linked to original sources
PubMed1982

Diagnosis of aortic insufficiency: comparison of auscultation and M-mode echocardiography to angiography.

We compared auscultation and M-mode echocardiography to supravalvular aortography in 75 patients with chronic aortic insufficiency. Angiographic evidence of aortic insufficiency was present in 66 patients and absent in nine. Auscultation had a sensitivity of 72.7% (48/66) and a specificity of 77.8% (7/9). Echocardiography had a sensitivity of 75.8% (50/66) and specificity of 77.8% (7/9). When both methods were used in combination, their sensitivity for diagnosis of aortic insufficiency increased to 92.9% (61/66). The specificity did not change. Our data suggest that when used alone neither auscultation nor echocardiography is a sensitive method for detecting aortic insufficiency, but when used in combination they are excellent indicators for the presence or absence of aortic insufficiency.

Aortic Valve↗
PubMed1981

Left ventricular mass by M-mode echocardiography in cardiac transplant patients with acute rejection.

Serial determination of left ventricular mass, right ventricular and left atrial size, fractional shortening and left ventricular systolic time intervals were made from M-mode echocardiograms in 13 long-term survivors with cardiac allografts These measurements were correlated with presence or absence of acute rejection as determined by myocardial biopsy. Left ventricular mass increased significantly, from a baseline of 129.8 +/- 11.8 (mean +/- SEM) to 310.5 +/- 13.0 g during 12 episodes of rejection. In contrast during eight episodes without rejection, the left ventricular mass did not increase significantly (baseline 175.2 +/- 11.8 to 211.9 +/- 25.6 g). There was no relationship between changes in right ventricular and left atrial size, fractional shortening or systolic time intervals and presence or absence of rejection of myocardial biopsy. An increase in left ventricular mass by M-mode echocardiography offers a reliable noninvasive method for detection of acute rejection of a cardiac allograft.

Echocardiography↗
PubMed1980

The benign hypermobile joint syndrome.

Benign hypermobility as defined by a modification of the Carter-Wilkinson criteria was found in 31 of 637 healthy blood donors, a prevalence of 5%. No increased prevalence of arthritis/arthralgia or characteristics suggestive of Ehlers-Danlos syndrome other than a possible familial predisposition were found when these 31 hypermobile subjects were compared to an age and sex matched two-for-one control group. Cardiac evaluation by auscultation, electrocardiogram, and echocardiogram showed no increased occurrence of mitral valve prolapse in hypermobile subjects. Thus the benign hypermobile joint syndrome appears to be one extreme of the range of normal joint motion and not a systemic connective tissue disorder.

Adult↗
PubMed1978

Characterization of normal and abnormal pulmonary surface by reflected ultrasound.

The use of reflected ultrasound in the diagnosis of pulmonary disease has been limited due to the strong reflection and high absorption of acoustic energy by alveoli containing air. Our study reports the ultrasonic characteristics of normal and diseased pulmonary surface. Two measurements, the coefficient of pulmonary reflection and the tissue frequency signature, were studied with specially calibrated instuments. The coefficient of pulmonary reflection in 23 normal subjects was - 19.6 +/- 0.1 dB at 5.5 MHz. In ten patients with documented pulmonary emboli, the coefficient of pulmonary reflection was -47.4 +/- 0.1 dB, significantly less than normal (P less than 0.1). The tissue frequency signature in 18 normal subjects was specular at higher and nonspecular at lower frequencies, with a typical dip at 5.2 MHz. In patients with chronic obstructive pulmonary disease, the tissue frequency signature was flat, and the typical dip was absent. In patients with pulmonary emboli, the characteristic shape of the tissue frequency signature was preserved, but there was a generalized loss of magnitude of the reflection. Thus, our preliminary data indicate that reflected ultrasound provides a noninvasive method for differentiating normal from diseased pulmonary surfaces.

Animals↗
PubMed1977

Neurogenic coronary vasoconstrictor effects of digitalis during acute global ischemia in dogs.

The rapid i.v. administration of digitalis has recently been shown to cause a substantial increase in coronary vascular resistance in the normal heart. This neurogenically mediated decrease in coronary blood flow would be potentially detrimental if it occurred during ischemia. The present study evaluates the effects of i.v. acetylstrophanthidin and digoxin on coronary vascular resistance during acute global ischemia in 29 dogs anesthetized with chloralose and urethane. Under these conditions, 0.5 mg of i.v. acetylstrophanthidin in 15 dogs resulted in erratic increases in coronary vascular resistance. The peak rise was 12+/-5% above control (P less than 0.01). In 7 of the 15 dogs, the initial erratic rise in coronary vascular resistance culminated in a steep rise associated with acute elevation in left ventricular end-diastolic pressure, which in four dogs terminated in ventricular fibrillation. During the nonischemic control periods, the peak rise in coronary vascular resistance with acetylstrophanthidin was 16+/-1% above control (P less than 0.01). In five dogs, prior alpha adrenergic receptor blockade with phenoxybenzamine prevented the rise in coronary vascular resistance with acetylstrophanthidin during ischemia. Similar erratic increases in coronary vascular resistance were observed with i.v. digoxin (1 mg) during ischemia in three dogs. In two of these dogs, there was a progressive rise in coronary vascular resistance associated with elevation of left ventricular end-diastolic pressure and ventricular fibrillation. The increase in coronary vascular resistance with digoxin during ischemia was abolished with phenoxybenzamine in two additional dogs. Thus, i.v. digitalis in the ischemic heart results in potentially detrimental increases in coronary vascular resistance mediated through alpha adrenergic receptor stimulation.

Animals↗
PubMedDate not supplied

Role of ultrasonic tissue characterization to distinguish reversible from irreversible myocardial injury.

Tissue characterization reflects structural and functional integrity of tissues. Inasmuch as reversible ischemia causes no structural damage and irreversible ischemia results in persistent structural myocardial damage, we postulated that ultrasonic tissue characterization can distinguish the two types of injuries. Anesthetized open chest dogs underwent 15 minutes (group 1, n = 5) and 90 minutes (group 2, n = 8) of acute total occlusion of the left anterior descending coronary artery, followed by 3 hours of reperfusion. Myocardial ischemia-infarction was confirmed with segment shortening, electronmicroscopic examination, and triphenyl tetrazolium chloride staining. Integrated backscatter Rayleigh 5 (IBR5), a measure of ultrasonic backscatter, and Fourier coefficient of amplitude modulation (FAM), an index of cardiac cycle dependent variation in backscatter, were measured at baseline, during ischemia, and after reperfusion. Group 1 (reversible ischemia) showed an increase in IBR5 from -48 +/- 1.2 dB at control to -45 +/- 1.0 dB (p less than 0.01) during ischemia, which returned to baseline after reperfusion (-47 +/- 1.3 dB). FAM was blunted during ischemia (6.2 +/- 1.0 dB during control versus 1.2 +/- 1.0 dB during ischemia, p less than 0.01) and recovered completely during reperfusion. Segment shortening was abolished during ischemia (18% +/- 3% during control versus -12% +/- 5% during ischemia, p less than 0.01) and recovered partially during reperfusion (4% +/- 5%). The group 2 animals with irreversible myocardial injury showed an increase in IBR5, from -49 +/- 1.2 dB during control to -44 +/- 1.0 dB during ischemia (p less than 0.01) and paradoxical bulging of the ischemic region (17% +/- 3% to -7% +/- 3%, p less than 0.01) during ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Accuracy of color Doppler transesophageal echocardiography for diagnosis of patent foramen ovale.

This study assessed the sensitivity of color Doppler as compared with contrast study during transesophageal echocardiography for detection of a patent foramen ovale. We also evaluated the incidence of patent foramen ovale in younger (less than age 50, group 1) as compared with older (greater than age 50, group 2) patients. A total of 114 patients were studied. A patent foramen ovale was found in 17 patients: 7 of 39 (17.9%) in group 1 and 10 of 75 (13.3%) in group 2 (NS). The sensitivity of color Doppler as compared with contrast study was 33%. Our data suggest that color Doppler is a poor method of assessment for the presence of a patent foramen ovale and that patent foramen ovale remains prevalent in older as well as younger patients.

Adult↗
PubMedDate not supplied

Comparison of peak and modal aortic blood flow velocities with invasive measures of left ventricular performance.

The purpose of this study was to determine the accuracy of Doppler-derived modal and maximum velocity and peak and mean acceleration of ascending aortic blood for the assessment of left ventricular systolic function. Studies were performed in six anesthetized open-chest dogs. Doppler-derived modal velocity, maximum velocity, and peak and mean acceleration were compared with left ventricular dP/dt, maximum aortic blood flow, and rate of blood flow measured with an electromagnetic flow probe under varying inotropic states. Maximum Doppler velocity showed better correlation (r = 0.94, y = 0.34 + 3.95) with maximum aortic blood flow than the modal velocity (r = 0.85, y = 1.49 + 3.85x). Peak acceleration also correlated better with the rate of blood flow (r = 0.92, y = 12.3 + 4.92x) than the mean acceleration (r = 0.83, y = 12.2 + 4.27x). Modal and maximum velocity and mean and peak acceleration correlated well with left ventricular dP/dt. We conclude that peak modal and peak maximum velocity and peak and mean acceleration are accurate measurements of left ventricular function. Maximum velocity and peak acceleration are more accurate than modal velocity and mean acceleration.

Animals↗
PubMedDate not supplied

The effect of changes in afterload on Doppler echocardiographic indexes of left ventricular performance.

To investigate the influence of changes in afterload on Doppler echocardiographic determination of peak aortic blood velocity, mean acceleration, and systolic velocity integral, eight dogs with their chests opened were studied in four inotropic states at varying levels of heart rate and mean aortic blood pressure. Data were collected in the control state, at two different levels of dobutamine administration (5 and 10 micrograms/kg/min intravenously), and after administration of propranolol (0.5 mg/kg intravenously). In each inotropic state, phenylephrine was infused intravenously to produce at least two successive steady state increases of 10 mm Hg or more in mean aortic blood pressure. Within a given animal, peak velocity emerged as the Doppler index most closely correlated with changes in Qmax, dQ/dt, and dP/dt (r = 0.94, 0.91, and 0.89, respectively). Mean acceleration also correlated closely with the invasive indexes (r = 0.87, 0.89, and 0.89). The effect of changes in mean aortic blood pressure on Doppler index measurements was not statistically significant in any of the inotropic states and did not affect the closeness of their correlation with the invasive indexes. We conclude that Doppler echocardiographic measurements of aortic blood peak velocity and mean acceleration remained as sensitive to changes in the inotropic state under conditions of varying increases in afterload as did the conventional invasive indexes tested.

Animals↗
PubMedDate not supplied

Influence of echocardiography on management of patients with systemic emboli.

To determine the impact of echocardiography in management of patients with systemic embolism, we retrospectively reviewed medical records and echocardiograms of 191 consecutive patients with suspected systemic embolism. One hundred sixteen patients had two dimensional echocardiograms and 75 patients had M-mode echocardiograms only. Patients were divided into three groups: Group 1 had no cardiovascular disease; Group 2 had cardiovascular disease, and Group 3 had hypertension only. Changes in therapy following echocardiogram were defined as initiation or discontinuation of anticoagulants or antiplatelet agents, cardioversion, or surgical intervention. M-mode echocardiogram did not identify any heart as a likely source of systemic embolism. Two dimensional echocardiogram defined 13 hearts as likely sources of emboli. All of these patients had known cardiovascular disease. Four of 13 patients (30.7%) whose hearts were likely sources of emboli had a change in therapy compared with 42 of 126 patients (33.3%) with low probability echocardiograms. We conclude that M-mode echocardiogram has no role in evaluation of patients with systemic emboli. Two dimensional echocardiogram may identify the heart as a source of emboli in patients with cardiovascular disease but does not alter early management.

Adult↗