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Biomedical subjects

N C Nanda

Publications and source records attributed to N C Nanda.

At least 163 records · Page 9Linked to original sources
PubMed1983

Myocardial texture characterization by two-dimensional echocardiography.

Twenty-four normal subjects and 181 patients with various cardiac disorders (36 autopsies) were studied by 2-dimensional echocardiography. In vitro echocardiographic studies were performed on 26 of 36 autopsied hearts utilizing an ultrasonically visible metallic probe to correlate myocardial echo patterns with histopathologic features. All normal subjects and the majority of patients with ventricular hypertrophy due to valvular or hypertensive lesions showed a uniformly speckled or an echolucent appearance of the myocardium (type I texture). No autopsied heart with this texture had gross fibrosis (visible to the naked eye) or infiltrative disease. All patients with infiltrative disorders (amyloidosis, 7 of 7; Pompe's disease, 4 of 4) had multiple, discrete, and small (3 to 5 mm) highly refractile echoes (HREs) in the myocardium involving the ventricle or ventricles completely (type IIA texture) or partly (type IIB texture). However, this finding was non-specific and was observed in many other conditions such as left heart hypoplastic syndrome (10 of 10), hypertrophic cardiomyopathy (19 of 26), and chronic renal failure (4 of 9). In the noninfiltrative group, HREs in the autopsied cases were shown to result from gross fibrosis or endocardiofibroelastosis utilizing in vitro echocardiographic studies and metallic probe-guided biopsies, while HREs in the autopsied cases with cardiac amyloidosis could be correlated only with amyloid deposits since fibrosis was absent. Larger HREs (greater than 5 mm) presenting as broad patches or long linear echoes in the myocardium (type IIC texture) was seen in old myocardial infarctions (9 of 21) and congestive cardiomyopathy (4 of 26) and were correlated with large areas of myocardial fibrosis. Two-dimensional echocardiographic studies of myocardial texture help identify various infiltrative and degenerative processes in the heart.

Adult↗
PubMed1983

Two-dimensional echocardiographic detection of left ventricular wall impaction by mitral prosthesis.

Real-time two-dimensional echocardiographic (2DE) studies detected impaction of the Starr-Edwards mitral valve prosthesis with the left ventricular wall in eight patients (septum in seven, posterior wall in one). One patient with echocardiographic evidence of posterior wall impaction died; autopsy revealed grooving of the left ventricular posterior wall by the cage. Four of seven patients with ventricular septal impaction developed ventricular arrhythmias in the in-hospital postoperative period which were persistent and difficult to control in two patients, but were not fatal. None of the 22 patients without ventricular wall impaction had ventricular arrhythmias. 2DE appears to be a useful noninvasive technique in detecting left ventricular wall impaction by mitral prosthesis, a potentially lethal complication.

Adolescent↗
PubMed1983

Ejection fraction determination without planimetry by two-dimensional echocardiography: a new method.

A new method for determining ejection fraction by two-dimensional echocardiography was assessed in 60 patients undergoing angiography. In method A, the left ventricular minor axis was measured at the midventricular cavity level in end-systole and end-diastole using the apical four chamber view in the 60 patients. The left ventricular major axis was also measured from the left ventricular apex to the base of the mitral valve at end-systole and end-diastole. The ejection fraction was determined using a modified cylinder-ellipse algorithm. In method B, measurements of the left ventricular minor axis were made in 40 consecutive patients, at the upper, middle and lower thirds of the left ventricular cavity at end-systole and end-diastole of the same cardiac cycle and left ventricular major axis was measured as in method A. With use of the same algorithm, three regional ejection fractions were determined and averaged to yield the total ejection fraction. The two echocardiographic methods were compared with single plane cineangiography in all patients and with gated nuclear scanning in 14 patients. Reproducibility was assessed by interobserver comparison. Correlation was determined in all patients and then separately for those with echocardiographic wall motion abnormalities. The correlation coefficient for all patients was 0.79 (probability [p] less than 0.001) for method A and 0.90 (p less than 0.001) for method B. For patients with wall motion abnormalities, method A had a correlation coefficient of 0.38 (p less than 0.1) and method B showed much higher correlation with r = 0.82 (p less than 0.001). Corresponding values for methods A and B in patients without wall motion abnormality were 0.85 (p less than 0.001) and 0.88 (p less than 0.001), respectively. Unlike a previous study, this method directly measures fractional shortening of left ventricular major axis and ejection fraction values are not arbitrarily modified by type of wall motion abnormality. With this method, accurate measurement of ejection fraction can be made by two-dimensional echocardiography without planimetry. In the absence of echocardiographic wall motion abnormalities, a very simple method A suffices. If wall motion abnormalities are present, the regional ejection fraction method B provides excellent results.

Adult↗
PubMed1983

Two-dimensional and Dopple rechocardiographic identification of infrahepatic interruption of inferior vena cava with azygos continuation.

Congenital anomalies of systemic venous return have been associated with pacemaker complications. Awareness of the existence of these anomalies prior to catheterization can lead to the utilization of an alternate route for pacing, avoiding undue delay in the institution of pacing which may be urgently needed. Pulse Doppler echocardiographic demonstration of turbulent flow in the azygos vein and superior vena cava combined with subcostal two-dimensional echocardiographic finding of a small channel opening into the right atrium appear to be highly specific findings in the diagnosis of infrahepatic interruption of inferior vena cava with azygos continuation.

Azygos Vein↗
PubMed1983

Usefulness of Doppler echocardiography in cardiac pacing: assessment of mitral regurgitation, peak aortic flow velocity and atrial capture.

Doppler echocardiographic studies were performed in 14 patients with dual chamber pacemakers. Transmitral flow studies (12 patients) revealed absence of mitral regurgitation (MR) or no change in MR severity in 6, new development or increased MR during VVI and/or short or long AV interval lengths compared to more normal AV intervals (150-160 ms) in 5, and appearance of MR when the pacing mode was changed from VVI to DVI with a fixed AV interval of 250 ms in 1 patient. Aortic peak flow velocity measurements (7 patients) showed significant increases in stroke volume (range 9 to 25%, mean 19.5%) in all patients with DVI/VDD pacing compared to VVI pacing (4 patients) or to shortest available AV interval (3 patients). Presence of Doppler left atrial systolic flow correlated with evidence of atrial depolarization in all 7 patients in whom high quality 12-lead surface electrocardiograms were obtained. Our preliminary study demonstrates the value of Doppler echocardiography in the "fine tuning" of cardiac pacemaker parameters by assessment of presence, absence, or change in severity of MR, estimation of relative changes in stroke volume, and determination of atrial capture in different pacing modes and at various AV intervals.

Arrhythmias, Cardiac↗
PubMed1983

Doppler echocardiographic studies in sequential atrioventricular pacing.

Six patients with sequential atrioventricular pacemakers were studied by Doppler echocardiography. A commercially available continuous wave system (transcutaneous aortovelography) was used and the transducer was placed in the suprasternal notch and angled to obtain peak aortic arch blood flow velocity. Changes in Doppler peak velocity have been previously shown to correlate closely and reliably with changes in hemodynamically measured stroke volume/cardiac output in the same patients following interventions. In all patients, the pacemaker was programmed from DVI mode to VVI (heart rate was kept constant) and then back to DVI, with the Doppler transducer held in a fixed position all the time, and peak velocities measured after the patient had been in any particular mode for at least 1 minute. Five of 6 patients showed reduction in peak velocities ranging from 13-25% (mean 18.4%) when the pacing mode was switched from DVI to VVI. Doppler peak velocity remained unchanged in 1 patient. Doppler echocardiography represents a simple, noninvasive method for estimating increments in stroke volume/cardiac output obtained with sequential AV pacing.

Atrioventricular Node↗
PubMed1982

Two-dimensional echocardiographic identification of pulmonary artery branch stenosis.

Pulmonary artery branch stenosis is a not uncommon congenital lesion, noted in approximately 4% of children at the time of cardiac catheterization. Real-time 2-dimensional echocardiography was used to examine 10 patients with angiographically documented pulmonary branch stenosis. Five cases of pulmonary artery branch narrowing were identified by echocardiography without prior knowledge of angiographic findings. In 5 other patients whose angiographic results were known, the narrowings were identified in 4 of 5 cases. These results demonstrate the feasibility of evaluating pulmonary branch stenosis with the nonionizing, noninvasive method of 2-dimensional echocardiography.

Adolescent↗
PubMed1982

Three-dimensional reconstruction of echo-cardiographic images using the rotation method.

We describe a method for three-dimensional reconstruction of real time two-dimensional echocardiographic images using a rotation method. Seven tissue specimens were studied in a water bath and two-dimensional images were recorded by rotating the transducer every 30 degrees, from 0 to 180 degrees. Angular reconstruction of areas was obtained at different axial locations and volumes calculated by a Sigma 9 computer using axial summation without geometric assumptions. Using spatial coordinate data, three-dimensional perspective images could be plotted by the computer in any desired view. The volumes obtained by this method (range 90-231 ml) corresponded closely (R = 0.96) with volumes measured directly by water displacement (range 95-200 ml). Two patients were also studied with this technique by placing the transducer at the cardiac apex to record two-dimensional left ventricular and diastolic and end systolic images. Three-dimensional reconstructed volumes closely correlated with those obtained by left ventricular angiography. Ejection fraction in one patient was 52% by three-dimensional reconstruction, 47% by angiocardiography. In the other patient, the ejection fraction was 76% by three-dimensional imaging, 69% by angiocardiography. This preliminary study demonstrates the feasibility and simplicity of three-dimensional reconstruction using the rotation method.

Adult↗
PubMed1982

Two-dimensional echocardiography of intracardiac masses: echo pattern-histopathology correlation.

Two-dimensional echo patterns (EP) of 21 pathologically confirmed intra-cardiac masses (10 tumors, 6 thrombi and 5 vegetations) were correlated with histopathology. Three types of echo patterns were defined. Five tumors and 3 thrombi demonstrated a fine, speckled and uniform appearance (type AEP) and none had any hemorrhages or calcification on pathological examination. Three left atrial masses showed large and discrete echolucent areas (type B EP) and histopathological correlation revealed large hemorrhages in the tumors and a large area of clot lysis in the thrombus. Three tumors, 2 thrombi and 5 vegetations revealed either localized areas of bright echoes or appeared uniformly bright (type C EP) and on pathological examination, all had calcification and/or fibrosis. Two-dimensional echo patterns are useful in delineating some of the structural components of intracardiac masses.

Coronary Disease↗
PubMed1982

Left ventricular inflow obstruction and atrial septal defect: diagnosis by real time two-dimensional echocardiography.

This report describes the usefulness of real time two-dimensional echocardiography in the diagnosis of left ventricular inflow obstruction associated with atrial septal defect. Echocardiographically, left ventricular inflow obstruction was at the level of the mitral valve in case one, mitral and subvalvular in cases 2 and 3 and supravalvular in case 4 (left atrial membrane). In all patients the defect was of the secundum variety and was seen as a constant discontinuity in the atrial septal image. The diagnosis was confirmed in all patients by cardiac catheterization, surgery or autopsy.

Adult↗