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Biomedical subjects

R S Meltzer

Publications and source records attributed to R S Meltzer.

At least 73 records · Page 4Linked to original sources
PubMed1984

Spontaneous contrast in the inferior vena cava in a patient with constrictive pericarditis.

A 66 year old black man was examined because of fatigue and progressive right heart failure. A striking finding on his echocardiogram was intense and slow-moving contrast in the inferior vena cava. Cardiac catheterization revealed constrictive pericarditis, and pericardiectomy was performed. Postoperatively, spontaneous contrast was no longer present. This case helps explain the origin of spontaneous inferior vena cava contrast.

Aged↗
PubMed1984

Microbubbles have intracardiac velocities similar to those of red blood cells.

The slope of an individual contrast trajectory on M-mode echocardiography represents the projection of the intracardiac velocity vector of a microbubble in the direction of the sound beam. Doppler echocardiography measures this projection of red blood cell velocity. To ascertain whether microbubbles have similar intracardiac velocities to those of red blood cells, 11 subjects were studied during intravenous injections of 5% dextrose solution. The flow across the tricuspid and pulmonary valves was examined. Microbubble velocity was measured by M-mode contrast slope analysis and simultaneously by Doppler technique. Results from both methods were correlated with red blood cell velocity measured by Doppler recording at the same time in the cardiac cycle, shortly before appearance of contrast medium (3 to 8 beats before the corresponding contrast velocity measurements). In all subjects, 10 sets of three velocities each (M-mode slope and Doppler data before and during contrast injection) were obtained for each valve. Visual inspection of the Doppler tracings showed similar velocity profiles before and during contrast appearance; the signal intensity was greater with contrast. Quantitatively, microbubble velocity assessed by M-mode trajectory slopes correlated well with the Doppler-derived velocity of red blood cells (r = 0.98, p less than 0.001, slope of the regression line = 0.99, standard error of the estimate = 7 cm/s). Doppler velocities measured with and without contrast medium showed a similar correlation (r = 0.99, p less than 0.001, slope of regression = 1.01, standard error of the estimate = 6 cm/s). In individual subjects, the correlation coefficient between microbubble and red blood cell velocities ranged form 0.978 to 0.998.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Long-term follow-up of left ventricular thrombus after acute myocardial infarction. A two-dimensional echocardiographic study in 96 patients.

To determine the incidence, natural history, and relation to anticoagulant therapy of left ventricular thrombus (LVT) following acute myocardial infarction (MI), we performed two-dimensional echocardiography in 96 consecutive patients with isolated MI during the acute episode and after four and 12 months. Only patients with anterior MI received oral anticoagulant therapy on admission and throughout the study period. The LVT was identified in 21/65 patients with anterior and in 1/31 patients with inferior MI. The large majority of LVT cases were seen for the first time during the acute phase of MI. LVT was associated with a significantly higher peak value of CK-MB (118 +/- 24 vs 76 +/- 35, p less than 0.001) and Killip class (2.5 +/- 0.8 vs. 1.5 +/- 0.7, p less than 0.002). Patients with anterior MI and LVT more frequently had segmental dyskinesia during acute MI than patients without LVT (86 percent vs 18 percent, p less than 0.001). In four patients LVT resolved during the study period. Discontinuation of anticoagulant therapy in four patients with an aneurysm led to LVT formation in three. Two patients suffered a clinically recognized embolic event; one never had LVT demonstrated by echocardiography. Thus, LVT usually develops in the early days following large anterior MI, complicated by pump failure and segmental dyskinesia, even when patients receive oral anticoagulant therapy. Surprisingly, the incidence of embolic events was low (1/22) in our LVT patients.

Administration, Oral↗
PubMed1983

Diagnosing tricuspid regurgitation by direct imaging of the regurgitant flow in the right atrium using contrast echocardiography.

To determine whether tricuspid regurgitation (TR) can be diagnosed by direct imaging of regurgitant flow in the right atrium (RA) using contrast echocardiography, echocardiography was performed in 35 patients using peripheral intravenous injections of 5% dextrose solution. Fifteen patients had TR judged by v-wave synchronous contrast appearance on the inferior vena cava echogram (a previously validated method for diagnosing TR), 5 of whom had clinically obvious TR. Twenty patients had no TR on inferior vena cava contrast echocardiography, 9 of whom were normal volunteers. On subsequent blind review, 13 of the 15 patients with TR were correctly identified on the basis of the regurgitant contrast flow just posterior to the tricuspid valve in the RA. Of the 20 without TR, 19 were correctly identified and there was 1 false-positive result. Using different criteria for the diagnosis (insisting on imaging of flow across the tricuspid valve in systole), another blinded observer correctly diagnosed only 8 of the 15 patients as having TR, but had no false-positive results. To avoid false-positive results, it is important to realize that there are 2 regions where retrograde flow can normally be seen in the RA: (1) briefly at the onset of systole coincident with tricuspid valve closure, and (2) in the posterior RA, as distinct from the anterior RA area just behind the tricuspid valve where TR is diagnosed in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Contrast echocardiography in pulmonary hypertension: observations explaining the early closure of the pulmonic valve.

We studied pulmonary artery flow patterns in 11 patients with pulmonary hypertension and 11 normal volunteers, by means of peripheral intravenous injections of 5% dextrose solution during M-mode echocardiography. Most of the patients had moderate to severe pulmonary hypertension. All normal subjects had antegrade flow throughout systole until just prior to pulmonic valve closure; none of the patients with pulmonary hypertension had continued antegrade flow throughout systole. The seven with early closure of the pulmonic valve showed abnormal retrograde flow of contrast in mid- to late systole; this was never observed in normal subjects. We conclude that early closure of the pulmonic value is seen in patients with early systolic retrograde flow in the pulmonary artery. A hypothesis for the pathogenesis of this flow is presented. Contrast M-mode echocardiography is a valuable new tool for the study of flow characteristics over the pulmonic valve. In patients with poor quality pulmonic valve echograms during systole, retrograde flow during midsystole imaged by contrast echocardiography may substitute for early closure as a sign of pulmonary hypertension.

Adolescent↗
PubMed1983

Comparison of two-dimensional echocardiography with radionuclide angiography during dynamic exercise for the detection of coronary artery disease.

Two-dimensional echocardiography (2DE) was performed during 30-degree left lateral decubitus bicycle exercise in 52 patients who underwent cardiac catheterization for suspected coronary artery disease (CAD). Adequate echocardiograms were obtained in 39 patients (75%). Thirty-five of these patients underwent radionuclide angiography (RNA) with the same exercise protocol as for echocardiography. Exercise-induced or increased initial asynergy was considered to be a positive test by both 2DE and RNA. Echocardiographic, scintigraphic, and coronary angiographic data were compared to each other. Significant CAD (greater than 50% luminal obstruction) was present in 26 patients (66%). One of 15 patients with exercise-induced asynergy by 2DE had no CAD. Six 2DE and two RNA studies during exercise were falsely negative, sensitivity 76% versus 91%. Inclusion of RNA ejection fraction data would increase the sensitivity but decrease the specificity of RNA. Exercise-induced septal asynergy was far more frequently present by 2DE than by RNA (11 versus 6) in the 17 patients who had exercise-induced anterior asynergy by both methods. We conclude that it was possible to perform exercise 2DE in 75% of our patients. Exercise-induced asynergy on 2DE was specific (92%) for CAD. The sensitivity of 2DE in detecting CAD was less than that of RNA.

Adult↗
PubMed1983

Systematic analysis of contrast echocardiograms.

Contrast echocardiography was first described in 1968. Since then, many reports have described clinical and experimental uses for the technique. Contrast echocardiography is performed at least occasionally in most echocardiography laboratories, but most physicians use this technique merely to determine the presence of a shunt or, more rarely, for structure identification. Contrast echocardiography can provide much more information. Some different types of information available from contrast echocardiographic records are discussed, including timing of contrast appearance within the cardiac cycle, relative timing of appearance in different cardiac structures, relative intensity of contrast opacification, cyclical changes in contrast opacification, negative contrast effect, slope of contrast trajectories on M-mode contrast echocardiography, and clearance times.

Contrast Media↗
PubMed1983

Accuracy of echocardiography versus electrocardiography in detecting left ventricular hypertrophy: comparison with postmortem mass measurements.

The accuracy of electrocardiography, M-mode echocardiography and two-dimensional echocardiography in predicting left ventricular hypertrophy was compared in 50 patients who came to autopsy within 6 months after the studies were performed. Several methods for determining left ventricular hypertrophy were examined for each of the three techniques. M-mode echocardiography was technically adequate to evaluate the presence or absence of left ventricular hypertrophy more often than either electrocardiography or two-dimensional echocardiography. Measurements from M-mode echocardiography also correlated best with autopsy measurements. Both echocardiographic techniques had a higher sensitivity than electrocardiographic criteria in diagnosing left ventricular hypertrophy. Two-dimensional echocardiography was not shown to improve the M-mode assessment of left ventricular hypertrophy. In an attempt to simplify both M-mode left ventricular mass calculations and the diagnosis of left ventricular hypertrophy for the clinician, a left ventricular mass nomogram was constructed, enabling quick insertion of standard M-mode echocardiographic measurements.

Adult↗
PubMed1983

Contrast echocardiographic shunts may persist after atrial septal defect repair.

We performed contrast echocardiography on 19 subjects who were asymptomatic in the postoperative period after surgical repair of atrial septal defects. Eighteen of these subjects had adequate right heart echocardiographic contrast to assess the presence or absence of right-to-left shunting. Multiple M-mode and two-dimensional echocardiographic views were studied during several contrast injections with and without the Valsalva manoeuvre. Six patients had postoperative shunts and 12 patients had no postoperative shunts. The age of the six patients with postoperative shunts was 26 +/- 10 years (mean +/- s.d.) and that of the 12 patients without postoperative shunts was 39 +/- 14 years. Four out of six of the postoperative shunt group were males and of these three had patch repairs compared with two males out of 12 with patch repair in the no shunt group. There were no definite differences between the two groups in the following variables: type of atrial septal defect (primum v. secundum), preoperative shunt size, pre-operative peak right ventricular pressure, pre-operative New York Heart Association functional class, pre- or postoperative right ventricular or left ventricular dimensions, aortic and left atrial dimensions. Four of the six patients with postoperative contrast echo shunting underwent cardiac catheterization, showing no significant step-up in oxygen saturation in three, and a significant shunt in one patient who had patch dehiscence at re-operation. We conclude that right-to-left shunts as demonstrated by contrast echocardiography are common in the late postoperative period after atrial septal defect repair. They need not indicate unsuccessful repair or a haemodynamically important residual shunt.

Adolescent↗
PubMed1983

Correlation between velocity measurements from Doppler echocardiography and from M-mode contrast echocardiography.

The slope of an individual contrast trajectory on M-mode contrast echocardiography represents a physiological variable similar to that measured by Doppler echocardiography: the projection of the intracardiac velocity vector in the direction of the sound beam. To test the hypothesis that M-mode contrast echocardiography slope measurement can yield information quantitatively similar to Doppler measurements, we performed both simultaneously in 11 normal volunteers. A pulsed Doppler unit capable of simultaneous M-mode and Doppler display was used. Contrast was obtained by intravenous injection of 5% dextrose. Two independent observers measured velocity simultaneously by both techniques at eight to 16 points per subject. One observer repeated the measurements a month later. All subjects had contrast, and 10 had sufficient quality tracings for simultaneous Doppler and contrast slope measurements. The correlation between velocity measurements by both techniques was good, though velocities by Doppler echocardiography were less than by M-mode contrast echocardiography. We conclude that the component of flow velocity towards or away from the transducer can be measured from M-mode contrast trajectory slopes as well as by Doppler echocardiography. M-mode contrast echocardiography may provide a practical method for verifying or calibrating Doppler measurements in vivo.

Adult↗
PubMed1983

Echocardiography in chronic aortic insufficiency. Is valve replacement too late when left ventricular end-systolic dimension reaches 55 mm?

To determine whether a ventricular (LV) end-systolic dimension (ESD) greater than or equal to 55 mm and LV left fractional shortening less than 25% are risk factors for aortic valve replacement (AVR) in patients with aortic insufficiency, we analyzed the clinical course and M-mode echocardiograms in 47 consecutive patients who underwent AVR for isolated symptomatic AI. Group 1 patients (n = 27) had a preoperative ESD less than 55 mm (mean 44 mm, range 30-52 mm) and group 2 patients (n = 20) had a preoperative ESD greater than or equal to 55 mm (mean 62 mm, range 55-85 mm). One patient in group 1 and 10 patients in group 2 had left ventricular fractional shortening less than 25%. There were no perioperative or postoperative deaths during an average follow-up of 41 months (range 6-76 months). Five patients had perioperative myocardial infarctions (MIs), three in group 1 and two in group 2. Since myocardial protection with cold potassium cardioplegia was instituted, no patient has suffered a perioperative MI. The average preoperative New York Heart Association functional classification was 2.3 (group 1) and 2.6 (group 2). Postoperatively, it was 1.2 in group 1 and 1.1 in group 2. Thirty-three patients (20 in group 1 and 13 in group 2) had echocardiograms at least 1 year after AVR. Of these, LV-end diastolic dimension decreased fro 67 +/- 6 to 53 +/- 6 mm (mean +/- SD) in group 1 (p less than 0.001) and from 79 +/- 3 to 55 +/- 6 mm in group 2 (p less than 0.001). The LVESD also decreased, but this is difficult to interpret because of frequent postoperative abnormal interventricular septal motion. The LV cross-sectional area, an index of LV mass, decreased in group 1 from 25 +/- 5 to 20 +/- 5 cm2 (p lss than 0.001) and in group 2 from 32 +/- 9 to 20 +/- 5 cm2 (p less than 0.001). Postoperative end-diastolic dimension and cross-sectional area were not significantly different between the two groups. We concluded that in aortic insufficiency, a preoperative ESD greater than or equal to 55 mm does not preclude successful AVR, as judged by long-term survival, symptomatic relief, and normalization of LV dimensions assessed by echocardiography.

Adult↗
PubMed1982

Inferior vena cava echocardiography.

The inferior vena cava can be imaged during echocardiography from the subcostal transducer position as an echo-free space at a depth ranging from 6 to 15 cm from the abdominal wall. The normal inferior vena cava M-mode echocardiogram has a "a" and "v" pulsation pattern similar to that seen in the jugular venous tracing and exhibits prominent cyclic respiratory changes. Since right atrial activity can be seen as a pulsation on the M-mode inferior vena cava tracing, specific patterns can be observed during cardiac arrhythmias. In right heart failure the inferior vena cava is usually distended, with diminished respiratory collapse. In tricuspid regurgitation, contrast injected into an arm appears in the inferior vena cava during the "v" wave. "A-wave synchronous" inferior vena cava contrast or a contrast appearance unrelated to the cardiac cycle, frequently with deep inspiration, does not suggest tricuspid regurgitation.

Arrhythmias, Cardiac↗
PubMed1982

Videodensitometric processing of contrast two-dimensional echocardiographic data.

We developed a computer program to analyze videodensity changes due to contrast appearance within a given operator-designated rectangle using two-dimensional echocardiograms previously recorded on videotape. Videodensity curves have been obtained from two-dimensional echocardiographic recordings in 14 patients after a total of 32 injections of 5% dextrose solution into the left ventricle during cardiac catheterization. The resulting videodensity vs time curves have some characteristics of indicator-dilution curves. The decay phase of these curves is largely mono-exponential. Potential clinical applications of this technique in measurement of ejection fraction, cardiac output and shunt quantification are discussed, as well as some potential limitations.

Computers↗
PubMed1982

Alternating atrial electromechanical dissociation as contributing factor for pulsus alternans.

Ten patients with mechanical pulsus alternans were studied by echocardiography and mechanocardiography. All had been or were in congestive heart failure. An atrial mechanism for pulsus alternans could be identified in two patients: one with primary congestive cardiomyopathy and one after aortic valve replacement for calcific aortic stenosis. Each strong systole was preceded by an "a" wave, while each weak systole was not. This was documented on both the apexcardiogram and the M-mode echocardiogram. Since both patients were in normal sinus rhythm with regular PP intervals, it was concluded that alternating atrial electromechanical dissociation was either the underlying mechanism or contributed to the pulsus alternans. Thus, alternating atrial electromechanical dissociation exists and may cause pulsus alternans. Pulsus alternans is not necessarily the result of left ventricular myocardial dysfunction alone.

Adult↗
PubMed1981

Intravenous carbon dioxide as an echocardiographic contrast agent.

Intravenous carbon dioxide (CO2) was employed to cause echocardiographic contrast in 40 patients. One to 3 cc of medically pure CO2 were agitated with 5 to 8 cc of 5% dextrose in water and rapidly injected into an upper extremity vein. Contrast was obtained in all patients. In 33 patients contrast density from 5% dextrose was compared with that from 5% dextrose-CO2 injections. Six of these patients had no contrast on the initial 5% dextrose injection and definite contrast with the subsequent injection containing CO2. Of the 33, 12 patients had initial contrast with 5% dextrose injections and greater contrast density when CO2 was added; 15 showed no definite difference; and none had less contrast with intravenous CO2-5% dextrose than with 5% dextrose alone. Intravenous CO2-5% dextrose is a useful method of increasing contrast in those patients who fail to demonstrate echocardiographic contrast when routine techniques are employed. It is also safe, provided precautions emphasized in this paper are observed.

Carbon Dioxide↗