Biomedical subjects
Publications and source records attributed to N C Nanda.
The recently developed innovative technique of Doppler color flow mapping permits real time visualization of blood flow patterns superimposed on two-dimensional echocardiographic images of the heart. This study demonstrates, for the first time, the usefulness of this technique in characterizing fetal cardiac dynamics.
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Pulsed Doppler echocardiography was used in conjunction with real-time two-dimensional and M-mode ultrasound techniques in 19 fetuses between 28 and 40 weeks of gestation. Of these, nine also had echocardiographic examination performed neonatally. In one fetus with complete heart block, pulsed Doppler echocardiography showed tricuspid regurgitation. The ventricular and atrial rates were accurately determined by M-mode ultrasound; pericardial effusion was noted in the two-dimensional examination. The left ventricular stroke volume, as measured by the Doppler technique, was 13.5 ml, and the minute output was 486 ml/min. In another fetus, Doppler studies assisted two-dimensional echocardiography in detecting pulmonary aneurysm. Neonatal echocardiography confirmed this and also showed the presence of tetralogy of Fallot. In three fetuses with ventricular ectopy, 30% to 50% reduction in the right ventricular stroke volume was recorded by the Doppler technique. This study demonstrates the clinical potential of pulsed Doppler echocardiography in assessing fetal cardiac disorders and justifies further investigation to define its clinical utility.
A thirty nine year old woman presented with ischaemic chest pain caused by a saccular aneurysm of the left coronary sinus of Valsalva. Over the next two weeks there was rapid dilatation of the aneurysm which led to left coronary artery compression and death from a massive myocardial infarction. It is suggested that early repair should be considered in patients with saccular aneurysm at this site, but only in the context of other management priorities.
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A complete echocardiography laboratory now offers not only M-mode and two-dimensional echocardiography but also pulsed, continuous-wave, and color Doppler flow mapping. There are innumerable practical applications of these combined modalities to the clinical management of patients with pacemakers. These include not only the anatomic documentation of lead position and diagnosis of perforations but also evaluation of pacing-related hemodynamics on a beat-to-beat basis. This is particularly valuable for "fine-tuning" multiprogrammable features of the pacing system in an individual patient.
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Ten patients with nondissecting aortic aneurysm and 10 with aortic dissection proved by angiography, surgery or both, were studied by real-time, 2-dimensional echocardiography. Multiple transducer positions were used to visualize various aortic segments so that a composite image of the aorta could be formulated. Using this comprehensive approach, the site, size and extent of all nondissecting aneurysms were correctly delineated (2 ascending aorta, 3 ascending aorta plus aortic root and 5 aortic arch with brachiocephalic involvement). In all patients with aortic dissection, the condition was identified by the presence of prominent, flap-like, undulating motion of the inner dissected wall or marked parallel wall widening (greater than or equal to 15 mm) and correctly categorized into DeBakey type I (4 cases), II (2 cases) or III (4 cases). Pulsed Doppler studies were useful in diagnosing reopening of dissection in a patient with previous surgical obliteration of the false channel.
Two-dimensional (2-D) echocardiographic studies were performed in 5 patients (2 adults, 3 pediatric cases) with proved aneurysm of the main pulmonary artery (PA). Two-dimensional echocardiography correctly localized the site of the aneurysm in all 5 patients and accurately categorized the type of aneurysm as saccular in 2 patients and fusiform in 3 patients. Fusiform aneurysms were characterized by their huge size, which made it impossible to image them completely in any single 2-D sector plane in 2 patients and by their tendency to cause displacement of the left atrium in 1 patient. Two-dimensional echocardiographic diagnosis of PA aneurysm was suggested prospectively without knowledge of angiographic findings in 3 of 5 patients. Two-dimensional echocardiography appears to be a useful noninvasive technique in the recognition of PA aneurysms.
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Adequate pulse Doppler echocardiographic (echo) studies of the fetus were performed in 15 of 16 subjects in the third trimester of pregnancy (28 to 36 weeks) using a commercially available Duplex system with a fast Fourier transform analyzer. A preliminary real-time 2-dimensional (2-D) echo examination was first performed to identify the fetal cardiac structures and obtain standard planes. The Doppler beam was then positioned along the long axis of the main pulmonary artery (PA), imaged in the standard short-axis or left ventricular-pulmonic plane, to obtain maximal Doppler frequency shifts. In 6 of 15 fetuses (40%) in whom the inner PA width could be measured, right ventricular (RV) stroke volume ranged from 1.01 to 3.76 ml. RV cardiac output ranged from 148 to 451 ml/min (128 to 239 ml/min/kg when normalized for estimated fetal weight). In 1 of 9 fetuses in whom PA width could not be reliably measured, a marked decrease (60%) in the PA flow velocity curve area and, therefore, in the stroke volume was noted during ectopic beats. In keeping with known fetal physiology, greater Doppler frequency shifts were noted in the right atrium than in the left atrium. Also, increased Doppler frequency shifts were noted in the left atrium during the open position of the valve of foramen ovale compared to its closed position. Our study shows the feasibility of studying normal and abnormal fetal hemodynamics noninvasively using Doppler echocardiography.
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Over a 13-year period, 18 pediatric patients received temporary transvenous pacing catheters for symptomatic bradycardia due to complete atrioventricular block or sinoatrial node dysfunction. Right ventricular wall perforation occurred in two patients. The utility of two-dimensional echocardiography in the detection and assessment of myocardial perforation by temporary pacing catheters is discussed.
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We assessed the feasibility and value of the cold pressor test (CPT) during real-time two-dimensional echocardiography (2DE) in patients with suspected coronary artery disease and normal resting left ventricular wall motion. Twenty patients were studied without knowledge of angiographic findings that demonstrated no significant coronary artery disease in seven (group 1) and significant coronary lesions in 13 (group 2). The increments in physiologic parameters (heart rate, systolic blood pressure, and double product) were not significantly different in both groups. CPT-induced wall motion abnormalities were identified echocardiographically in nine patients in group 2 and in one patient in group 1 (sensitivity 69% and specificity 86%). None of the patients in our study developed chest pain, ST changes, or ectopy during the test. It is concluded that 2DE combined with the CPT is valuable in identifying patients with coronary artery disease who show no left ventricular asynergy at rest.
We evaluated left ventricular function in patients with recurrent sustained ventricular tachycardia (VT) using two-dimensional echocardiography (2DE). Thirteen patients, 11 men and 2 women, age range 42-77 (mean 62 +/- 12) years were studied in sinus rhythm (SR) and immediately after VT induction. 2DE parameters analyzed included wall motion, mitral valve leaflet motion, and ejection fraction (EF). In SR, 21 segments/walls in 12 patients showed wall motion abnormalities (WMA) ranging from hypokinesis to dyskinesis and one patient had generalized LV hypokinesis. In VT, new WMA were noted in 2 patients. Thirteen segments/walls in 8 patients showed further worsening of pre-existing WMA. In 1 patient there was worsening of generalized LV hypokinesis. Three patients showed apparent improvement in pre-existing WMA during VT. In 2 patients large apical aneurysms showed a reduction of dyskinesis in VT. Mitral valve opening was intermittent in patients with shorter VT cycle lengths and was maximal when atrial systole preceded or coincided with ventricular depolarization. Doppler echocardiography in 1 patient confirmed the pattern of intermittent mitral flow, with greatest flow occurring when mitral valve opening occurred well before the QRS peak. In 5 patients, 2DE permitted EF measurements. EF in SR ranged from 24-56% (mean 36 +/- 13), decreased to 6-33% (mean 21 +/- 11) within the first ten beats of VT and 6-25% (mean 19 +/- 8) after twenty beats of VT. EF decreased more in patients with shorter VT cycles as compared to those with longer VT cycle lengths.(ABSTRACT TRUNCATED AT 250 WORDS)
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Real-time 2-dimensional (2-D) echocardiograms were performed in 4 patients, all with considerable obstruction within the right ventricular (RV) body, in 3 patients due to muscle bundles and in 1 due to hypertrophic cardiomyopathy (HC). None had obstruction at the pulmonic valve level or immediately below. Echocardiographically, obstruction presented in 3 patients as localized bulging of the RV free wall in the subinfundibular region such that the RV cavity presented a typical "hourglass" appearance. Associated ventricular septal defect (VSD) was detected in 2 patients by echocardiography. In the fourth case, a patient with HC, RV obstruction was associated with a prominent bulge of the ventricular septum into the right ventricle. In 3 patients, the obstruction was convincingly demonstrated only in the subcostal RV inflow-apex-outflow plane, rather than in the standard echocardiographic planes. Pulse Doppler studies in 2 patients demonstrated disturbed RV flow. Obstruction within the RV body is a potentially serious condition which has been overlooked both at cardiac catheterization and at surgery. Demonstration of this lesion by 2-D echocardiography appears feasible and would greatly improve diagnostic accuracy.