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Biomedical subjects

N C Nanda

Publications and source records attributed to N C Nanda.

At least 181 records · Page 10Linked to original sources
PubMed1982

Doppler evaluation of fetal hemodynamics.

Human umbilical hemodynamics was investigated in 27 pregnant patients with gestational ages from 29 to 43 weeks using a pulsed Doppler flowmeter. The signals were analyzed by Fast Fourier Transform using a minicomputer. Coherent averaging of the signals, along with the computation of maximum velocity, mean velocity and the first moment of Fourier spectra about the zero frequency axis were performed. Hemodynamic indices were measured utilizing a comprehensive feature characterization technique of the blood flow velocity waveform. It was observed that coherent averaging reduced spectral variance thus relatively simplifying the analyses. The Pulsatility Index based on the first moment of the Fourier spectra indicated a higher umbilical flow change during the fetal cardiac cycle, than that predicted by the peak velocity Pulsatility Index. We also observed a high Pulsatility Index in association with three cases of oligohydramnios indicating the possibility of an elevated placental circulatory impedance. Variation in the peak velocity up to 20% was also noted with fetal breathing movements. Further studies are necessary to determine the clinical relevance of these findings.

Female↗
PubMed1982

Doppler echocardiography and cardiac pacing.

There is a need for a non-invasive method to evaluate the hemodynamic consequences of pacing. The value of Doppler echocardiography in assessing relative changes in stroke volume and cardiac output is reviewed. We present preliminary observations illustrating the potential value of Doppler echocardiography in cardiac pacing.

Blood Flow Velocity↗
PubMed1982

Two-dimensional echocardiographic features of right ventricular infarction.

Real-time, two-dimensional echocardiographic studies were performed in 10 patients with acute myocardial infarction who had clinical features suggestive of right ventricular involvement. All patients showed right ventricular wall motion abnormalities. In the four-chamber view, seven patients showed akinesis of the entire right ventricular diaphragmatic wall and three showed akinesis of segments of the diaphragmatic wall. Segmental dyskinetic areas involving the right ventricular free wall were identified in four patients. One patient showed a large right ventricular apical aneurysm. Other echocardiographic features included enlargement of the right ventricle in eight cases, paradoxical ventricular septal motion in seven cases, tricuspid incompetence in eight cases, dilatation of the stomach in four cases and localized pericardial effusion in two cases. Right ventricular infarction was confirmed by radionuclide in seven patients, at surgery in one patient and at autopsy in two patients.

Aged↗
PubMed1981

Two dimensional echocardiographic evaluation of exercise-induced left and right ventricular asynergy: correlation with thallium scanning.

Adequate real time two dimensional echocardiograms were prospectively obtained before and immediately after graded treadmill exercise testing in 41 of 48 patients who underwent cardiac catheterization for suspected coronary artery disease. Findings were correlated with thallium perfusion scans performed 5 to 10 minutes and 3 hours after the same exercise test. Exercise-induced wall motion abnormalities were detected in 19 of 23 patients with significant coronary artery disease and no prior myocardial infarction as well as in all 5 patients with known previous infarction. Three patients with coronary artery disease experienced new isolated right ventricular asynergy with exercise that would have been missed if only the left ventricle had been evaluated. Exercise-induced thallium perfusion defects showed good correlation with exercise-induced asynergy as detected with echocardiography. Two dimensional echocardiography performed immediately after treadmill stress testing is a feasible and rewarding technique in the evaluation of patients suspected to have coronary artery disease.

Adult↗
PubMed1981

Two-dimensional echocardiographic features of atrial septal aneurysms.

Aneurysms of the interatrial septum are rare. They have been associated with complications such as embolic phenomena and atrioventricular orifice obstruction. We describe two patients, one adult and one child, with atrial septal aneurysms that were diagnosed by real-time, two-dimensional echocardiography. Atrial septal aneurysms appeared as thin, localized outpouchings of the atrial septum that protruded into the right atrium and showed marked variations in their contour and size during the cardiac cycle. They could be differentiated from other intra-atrial structures such as tumor mass, large eustachian valve and intra-atrial baffle by their relatively low reflectance, relationship to the atrial septum, considerable alterations in their outline during the cardiac cycle and characteristic patterns during peripheral venous contrast echocardiography.

Aortic Valve↗
PubMed1981

Real-time, two-dimensional echocardiographic features of pacemaker perforation.

Five patients (four adults and one child) with clinically suspected myocardial perforation by temporary transvenous pacemakers were studied by real-time, two-dimensional echocardiography. In three patients, the catheters were visualized passing through the right ventricular apical wall with the tip located outside the cardiac border. In one patient the catheter perforated the atrioventricular septum and entered the left ventricle with the tip lodged against the posterior wall. In another patient, the catheter had partially penetrated the ventricular septum near the apex. Pericardial effusion was observed in two patients, in one of whom it was localized to the site of perforation. No patient had evidence of cardiac tamponade. In four patients, the catheters were withdrawn under echocardiographic visualization and the catheter tips could be seen moving from the abnormal locations back into the right-heart chambers. Perforation was verified at autopsy in two patients, including one in whom the catheter was not withdrawn. Real-time, two-dimensional echocardiography appears to be valuable in the diagnosis of pacemaker perforation.

Cardiac Catheterization↗
PubMed1980

Echocardiographic evaluation of cardiac abnormalities in Duchenne's dystrophy and myotonic muscular dystrophy.

Routine echocardiographic examinations were performed on 53 individuals with muscular dystrophy (29 with myotonic muscular dystrophy [MMD] and 24 with Duchenne's dystrophy [DD]). Five of 29 (17%) with MMD and six of 24 (25%) with DD had typical mitral valve prolapse evidenced by echocardiography. All patients with DD and mitral valve prolapse had severe thoracic skeletal deformities, while none with MMD and mitral valve prolapse had such abnormalities. Other echocardiographic parameters analyzed included the fractional shortening of the left ventricle (% delta S), excursions of the left ventricular posterior wall (LVPW) and the ventricular septum, pre-ejection period/left ventricular ejection time ratios (PEP/LVET), and thickness of the LVPW and ventricular septum. Abnormal prolongation of the PEP/LVET ratio and increased thicknesses of the LVPW and ventricular septum were noted in some individuals in the MMD group. Decreased % delta S with diminished excursion and diastolic velocity of the LVPW were noted in some with DD.

Adolescent↗
PubMed1980

Differentiation of left ventricular pseudoaneurysm from true aneurysm with two dimensional echocardiography.

Real time two dimensional echocardiographic findings in four patients with a pathologically proved left ventricular pseudoaneurysm were compared with those in seven patients with a similarly proved true aneurysm of the left ventricle. Pseudoaneurysms produced a bounded echo-free space with a narrow neck that communicated with the leftventricular cavity. The maximal internal width of this neck (Omax) was much smaller than the maximal parallel internal diameter (Dmax) of the aneurysmal sac, and the ratio Omax/Dmax never exceeded 0.5. In all cases the pseudoaneurysm could be seen extending behind the intact portion of the involved left ventricular wall, and this finding produced a characteristic beak-like configuration in the studies of two patients. In contrast, true aneurysm resulted in local bulging and dilatation of the left ventricular wall so that the maximal internal width of the mouth (Omax) was nearly equal to, or actually represented, the maximal internal diameter (Dmax) of the aneurysm so that the ratio Omax/Dmax ranged from 0.9 to 1.0. Our preliminary study indicates that real time two dimensional echocardiography is useful in differentiating pseudoaneurysm from true aneurysm of the left ventricle.

Adult↗
PubMed1980

Noninvasive diagnosis of mitral prosthesis malfunction.

We describe the utilization of echocardiography and phonocardiography in the diagnosis of malfunction of the Smeloff-Cutter mitral prosthesis in a patient in whom corrective surgery was subsequently performed without the necessity of cardiac catheterization studies. The noninvasive studies also delineated prosthesis malfunction as the etiology of pulsus alternans, noted clinically in this patient.

Adult↗
PubMed1980

Real time two-dimensional echocardiography in the diagnosis of left atrial myxoma.

A patient with a left atrial myxoma is reported in whom M-mode echocardiography was atypical and misleading since in most transducer positions, no tumor echoes were found in the left atrium. Real time two-dimensional echocardiography provided a definitive diagnosis, demonstrating a large left atrial mass with multiple areas of calcification. One such calcified area was located adjacent to the posterior aortic wall, and the tumor echoes were sparsely imaged directly behind it due to incomplete penetration of the ultrasound beam through dense calcification (acoustic shadowing). Difficulty in M-mode diagnosis appeared to result from this acoustic shadowing effect. In our patient, two-dimensional echocardiography was superior to the M-mode in making a definitive diagnosis of left atrial tumor because of the difficulty visualizing tumor echoes in the left atrium.

Calcinosis↗