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R S Meltzer

Publications and source records attributed to R S Meltzer.

At least 55 records · Page 3Linked to original sources
PubMed1988

Myocardial contrast two-dimensional echocardiography: dose-myocardial effect relations of intracoronary microbubbles.

It is controversial whether echocardiographic contrast agents prepared by sonication cause transient myocardial depression beyond that known to occur with contrast agents alone. In nine open chest dogs, contrast injections were made into the left anterior descending coronary artery during two-dimensional echocardiography. One hundred forty-four recordings were analyzed subsequently, by an observer who was unaware of other data, for percent depression of systolic wall thickening, duration of regional wall motion abnormalities, peak contrast enhancement and contrast washout. Two microbubble sizes were obtained by sonicating Renografin-76 (meglumine sodium diatrizoate): mean diameter 12 +/- 3 (SEE) and 20 +/- 6 micron. Four doses (range 0.5 to 3 ml) of each of four agents (12 and 20 micron bubbles in Renografin, nonsonicated Renografin and saline solution) were injected in random order. Significant relations were found between percent depression of systolic wall thickening, duration of regional wall motion abnormalities and contrast washout time versus microbubble size (p less than 0.001) and microbubble dose (p less than 0.01). Little increased contrast effect was found at larger doses or with larger microbubbles compared with the smaller doses and size studied. Injections of nonsonicated Renografin caused less depression of systolic wall thickening (p less than 0.05), faster resolution of wall motion abnormalities (p less than 0.05), less contrast (p less than 0.001) and more rapid contrast washout (p less than 0.001) than did 12 micron bubbles in Renografin. A significant correlation was found between the duration of regional wall motion abnormalities and contrast washout time (r = 0.93, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Determination of ejection fraction from contrast echocardiography using videodensitometry in an in vitro model.

To examine whether ejection fraction can be estimated by videodensitometric analysis of contrast washout from a chamber, a model was constructed consisting of a 60-ml syringe and a modified Harvard respirator. Ejection fraction could be adjusted mechanically. Echocardiographic images were recorded on videotape and analyzed on an offline computerized analysis system. To calibrate the relationship between target concentration and videodensity on our sector scanner-videodensity analysis system, we used a phantom with constant attenuation and eight cones with known, varying relative scatterer concentration. The time-gain-compensation curve was kept constant on the ultrasound instrument and videodensity was measured from videotapes by an offline computer system. In the image of each cone, a 10 X 70 pixel operator-designated region of interest was chosen, and mean videodensity/pixel (256 level gray scale) was calculated. A logarithmic relation was found between scatterer concentration and videodensity. This excellent log relationship existed at all three gain levels studied: at 40% of maximum gain, r = .96; at 50% gain, r = .99; and at 60% gain, r = .99 (all p less than .001). Boluses of .5 ml sonicated Hypaque were then injected into the chamber and the contrast washout was recorded at ejection fractions of 20, 30, 40, 50, 60, and 70%. Bolus delivery and complete contrast mixing was attained except at ejection fraction 20%. Using the first two to four stroke videodensity decay the ejection fraction was calculated by estimating microbubble concentration decline using the logarithmic regression equation between videodensity and scatter concentration obtained during calibration.(ABSTRACT TRUNCATED AT 250 WORDS)

Densitometry↗
PubMed1987

Left ventricular function at similar heart rates during tachycardia induced by exercise and atrial pacing: an echocardiographic study.

M mode echocardiography was used in 10 normal subjects to study left ventricular dimension and function variables at identical heart rates during tachycardia induced by supine bicycle exercise or atrial pacing. Echocardiographic data were analysed independently by two observers. The maximum heart rate reached during atrial pacing was lower (mean (1SD) 148 (17) beats/min) than that reached during exercise (mean (1SD) 167 (14) beats/min). The left ventricular end diastolic dimension was greater before supine exercise than before atrial pacing, probably as a result of leg raising. At each graded exercise step the end diastolic dimension remained greater than during atrial pacing and the differences became progressively greater with increasing heart rates. The left ventricular end systolic dimension was not significantly different at each step during the two stresses. During recovery the end systolic dimension was significantly smaller after exercise than at corresponding heart rates induced by atrial pacing. Left ventricular function indices--fractional shortening and peak rates of left ventricular systolic and diastolic dimensional change--were significantly higher during exercise than during atrial pacing and the differences increased with heart rate. It is concluded that the intervention used to change heart rate has an important effect on M mode echocardiographic left ventricular dimensions; indices of left ventricular performance increase progressively during exercise and differ from those measured at the same heart rate during atrial pacing; it is important to consider heart rate, stroke volume, and loading conditions when reference values are used and when the effects of a particular stress are to be interpreted.

Adult↗
PubMed1986

Incidence, timing and prognostic value of left ventricular aneurysm formation after myocardial infarction: a prospective, serial echocardiographic study of 158 patients.

Serial 2-dimensional echocardiography was performed prospectively in 158 consecutive patients with first acute myocardial infarction (AMI) to determine the incidence of left ventricular (LV) aneurysm formation and the time course required for, and the clinical significance of, onset of LV aneurysm formation. Studies were performed throughout the first 5 days and after 3 months and 1 year. LV aneurysm was defined as an abnormal bulge in the LV contour during both systole and diastole. Eighty-four patients had anterior, 68 posterior and 6 anteroposterior AMI defined echocardiographically. During the study period, LV aneurysm was found in 35 of 158 patients (22%): in anterior AMI in 27, in posterior AMI in 6 and in anteroposterior AMI in 2. No new aneurysm developed after 3 months. Early aneurysm formation, during the first 5 days after AMI, was seen in 15 patients with anterior infarction. Twelve of these 15 (80%) died within 1 year (10 within 3 months), in contrast to 5 (25%) of the remaining 20 patients with LV aneurysm (p less than 0.05). Dyskinesia of the anterior wall in the acute stage usually resulted in aneurysm formation. Thus, LV aneurysm formation is seen in 22% of mostly anterior AMI and occurs within 3 months after AMI. Early aneurysm formation is associated with a high 3-month (67%) and 1-year (80%) mortality rate.

Echocardiography↗
PubMed1986

Two-dimensional echocardiography during percutaneous transluminal coronary angioplasty.

In order to study myocardial and clinical events during transient coronary occlusion in humans, two-dimensional echocardiography was continuously performed in 15 patients undergoing 49 balloon inflations during percutaneous transluminal coronary angioplasty (PTCA). Transient segmental asynergy developed in all patients 8 +/- 3 seconds after balloon inflation and returned to baseline 19 +/- 8 seconds after balloon deflation. Segmental dyskinesis was seen in only 8 of 11 patients undergoing PTCA of the left anterior descending artery (LAD). A wall motion score, based on degree of asynergy of 13 segments of the left ventricle, was significantly higher during LAD than during right coronary artery inflation (7.9 +/- 1.3 vs 4.0 +/- 1.4, p less than 0.01). Left ventricular size index increased significantly during balloon inflation, from 179 +/- 9 to 196 +/- 10 mm (p less than 0.01). Four patients developed transient ST segment changes in the extremity leads of the ECG and five patients had angina pectoris. The very first sign of ischemia in three patients, who developed all of these symptoms together, was consistently asynergy, followed by ECG changes, and last, angina pectoris. Thus during PTCA, transient asynergy and left ventricular dilatation develop, which are often clinically silent.

Angina Pectoris↗
PubMed1986

Intracardiac thrombi and systemic embolization.

Recent progress has been made in diagnosing and tracing the natural history of intracardiac thrombi by echocardiography. Left ventricular thrombi occur and cause emboli in three clinical conditions: acute myocardial infarction, left ventricular aneurysm as a sequel to infarction, and idiopathic dilated cardiomyopathy. Echocardiographic studies have shown that one third of patients with acute anterior myocardial infarction have left ventricular thrombi; only a small percentage of these patients have emboli. Administration of anticoagulants decreases the prevalence of left ventricular thrombi and the frequency of embolization in this group. Thrombi that are protruding and mobile are most likely to embolize. Anticoagulation treatment decreases the prevalence of embolization in idiopathic dilated cardiomyopathy and should be instituted regardless of whether atrial or ventricular thrombi are detected by two-dimensional echocardiography. In patients with chronic left ventricular aneurysm, thrombi occur commonly, but emboli, infrequently. Therefore, data are insufficient to suggest that anticoagulation treatment is indicated, even if left ventricular thrombi are detected by two-dimensional echocardiography.

Anticoagulants↗
PubMed1985

Assessment of left ventricular aneurysm resectability by two-dimensional echocardiography.

Mortality of surgical resection of a left ventricular (LV) aneurysm is largely determined by size and function of nonaneurysmal or residual myocardium. A residual myocardial index was determined using 2-dimensional echocardiography (2-D echo) in 56 consecutive patients scheduled for LV aneurysmectomy, and these results were correlated with surgical outcome. The index was calculated using 3 apical cross sections: the 2- and 4-chamber views and the long-axis view. These views were recorded at mutual angles of 60 degrees. In each view the end-diastolic length of normally moving endocardium of the 2 opposite walls was expressed as a fraction of the end-diastolic LV long axis. The index was assessed by averaging the 6 ratios obtained. In 41 survivors the index ranged from 40 to 71% (mean +/- standard deviation 53 +/- 7.8) and in 15 nonsurvivors from 29 to 67% (mean 38 +/- 8.5, p less than 0.01). With 1 exception, this echocardiographic index sharply separated survivors from nonsurvivors. The lower limit to survive aneurysmectomy was 40%.

Adult↗
PubMed1985

Spontaneous echographic contrast in the inferior vena cava.

The inferior vena cava was examined for spontaneous contrast by two-dimensional echocardiography in 106 consecutive patients. Images of the inferior vena cava in six patients were inadequate and were excluded from further analysis. The study population included 100 patients, 41 men and 59 women. Twenty-three patients had an intravenous line or heparin lock in place at the time of the echocardiographic examination. Ten patients had definite contrast in the inferior vena cava, seven had equivocal contrast, and 83 had no contrast. The three groups did not differ significantly with respect to sex distribution, age, associated diagnoses, or inferior vena cava dimension. We concluded that spontaneous inferior vena cava contrast is commonly seen in adults, both normal subjects and patients with various types of heart disease. There was no specific category of heart disease that predominated in patients with spontaneous inferior vena cava contrast. Although it may be associated with impairment to filling of the right side of the heart and may resolve when normal right heart hemodynamics are restored, spontaneous inferior vena cava contrast is usually a finding with little clinical import. Several possible etiologic factors include microbubbles and aggregates of formed blood elements. Spontaneous inferior vena cava contrast is seen more frequently with a higher frequency imaging system.

Adolescent↗
PubMed1985

Myocardial perfusion imaging in humans by contrast echocardiography using polygelin colloid solution.

This study evaluated the myocardial contrast effect and safety of polygelin colloid solution selectively injected into the coronary arteries in 25 patients during two-dimensional echocardiography. Six patients (group I) had selective intracoronary injections of nonagitated and 19 (group II) of hand-agitated polygelin colloid solution. Myocardial contrast was seen on two-dimensional echocardiographic cross sections in three patients of group I and in all patients of group II; in 16 patients it was also seen on M-mode echocardiograms. The contrast effect lasted for 15 to 60 seconds. The intensity of myocardial opacification was not significantly influenced by the amount of polygelin colloid solution injected, heart rate or cardiac size. The total number of contrast-enhanced segments after right and left coronary artery injections delineated the entire cross-sectional area in any given view. None of the patients developed symptoms during or immediately after the injections. One patient had transient second degree atrioventricular block after a right coronary wedge injection, one patient showed a QRS axis shift and two others had transient T wave changes. There were no aortic blood pressure changes and no significant serum enzyme (creatine kinase [CK], CK-MB fraction, glutamic oxaloacetic transaminase) elevation or alterations of left ventricular function assessed echocardiographically. It is concluded that hand-agitated polygelin colloid solution is a useful and safe intracoronary contrast agent for delineating myocardial perfusion areas on two-dimensional echocardiography in humans.

Adolescent↗
PubMed1985

Embolic potential of left ventricular thrombus after myocardial infarction: a two-dimensional echocardiographic study of 119 patients.

Left ventricular thrombus complicating myocardial infarction was diagnosed by two-dimensional echocardiography in 119 patients. The infarct site was anterior in 98 patients and inferior in 11. Systemic embolism occurred in 26 patients (stroke in 18, lower limb embolism in 7 and mesenteric embolism in 1). A protruding configuration of the thrombus was more common in the patients with embolism than in those without (23 [88%] of 26 versus 17 [18%] of 93) (p less than 0.01). Free mobility of the thrombus was found in 15 (58%) of 26 and 3 (3%) of 93 cases, respectively (p less than 0.01). In predicting embolism, protruding thrombus configuration had a sensitivity of 88% and a specificity of 82%, and positive and negative predictive accuracy was 57 and 96%, respectively. For free mobility of the thrombus, sensitivity was 58%, specificity 97%, positive predictive accuracy 85% and negative predictive accuracy 89%. In the 46 patients whose echocardiogram was obtained during the hospital admission for the index infarct, repeat echocardiograms were obtained during oral anticoagulant therapy. Twelve of these 46 patients had embolism and 2 of the 12 died. In seven of these patients, full dose oral anticoagulant therapy had been given before embolism occurred and in five it was started after an embolic event. The thrombus decreased in size or disappeared in six patients; in four the thrombus showed no change, and in two of these four emboli recurred despite anticoagulation. It is concluded that two-dimensional echocardiography may help delineate the embolic potential of left ventricular thrombus complicating myocardial infarction and may be of value in weighing the benefits and disadvantages of oral anticoagulant therapy.

Anticoagulants↗
PubMed1985

Generating precision microbubbles for use as an echocardiographic contrast agent.

To investigate whether precision microbubbles can be simply generated and used for quantitative contrast echocardiographic studies, precision microbubbles were fabricated in gelatin using a simple generator. The generator consisted of a fluid pump, a generating site containing a narrow bore tube and a bubble stream output port. Up to 5,000 microbubbles/s were generated with a controllable radius of 80 to 150 mu. No detectable interbubble size variation was observed under high power microscopy. To examine whether these bubbles could be used for quantitative contrast echocardiographic studies, they were then infused into a tube with a known flow of degassed water during ultrasonic imaging. The resulting ultrasonic contrast effect in the tube lumen at steady state was recorded and subsequently measured by videodensitometry. The precision microbubbles were visually and microscopically stable during the experimental run. Correlations between microbubble infusion rate and luminal videodensitometry on individual runs were r = 0.89, 0.83, 0.73 and 0.71. It is concluded that precision microbubbles can be generated in sufficient quantities on site to serve as an echocardiographic contrast agent for quantitative studies in vitro and at a very modest cost. These precision microbubbles are sufficiently stable to be collected and stored for short periods of time.

Air↗
PubMed1985

Mitral valve prolapse. Quantitative analysis and long-term follow-up.

Forty-two patients with systolic posterior motion of the mitral valve on M-mode echocardiogram were reevaluated after a mean clinical follow-up of 6.7 years and an echocardiographic follow-up of 5.1 years. A new method for quantitation of mitral valve prolapse (MVP) is presented. A straight line (A) was drawn connecting the site of posterior leaflet motion with the D point of the subsequent diastole. A vertical line (B), termed "the degree of MVP," was drawn from the site of maximal MVP to line A. The degree of MVP was then correlated with various clinical and ECG parameters and with the presence of complications. Measurements could be taken in 21 patients; the mean degree of MVP increased from 5.9 +/- 2.1 to 7.1 +/- 2.9 mm (P less than 0.01), and mean left atrial size increased from 3.0 +/- 0.5 to 3.5 +/- 0.8 cm (P less than 0.01). No correlation was found between the degree of MVP and symptoms, auscultatory findings or the presence of complications. There were no deaths and in none was life-threatening arrhythmia documented. The complications we encountered were endocarditis in five patients, transient ischemic attacks in two and cardiac arrest during surgery in one. We conclude that 1) the degree of MVP can be measured by M-mode echocardiography; 2) there seems to be no correlation between the degree of MVP and the patient's clinical state; 3) complications in MVP are rather frequent; and 4) left atrial size and degree of MVP tend to increase with time, which may indicate a progressive nature of the disease.

Adolescent↗
PubMed1984

Two-dimensional echocardiographic appearance of left ventricular thrombi with systemic emboli after myocardial infarction.

To test the hypothesis that left ventricular (LV) thrombi that project into the lumen and are mobile are more likely to embolize than those that do not have these characteristics, the 2-dimensional echocardiograms of 16 patients with LV thrombi after myocardial infarction were retrospectively reviewed. Ten had evidence of peripheral embolization and 6 did not. The studies were reviewed in random order by an observer blinded to the clinical data. Each echocardiogram was graded as showing a protruding or nonprotruding thrombus and the presence or absence of increased mobility. The thrombus projected into the lumen on the echocardiograms of 8 of 10 patients who had had emboli and in 0 of 6 who had not. The thrombus had increased mobility in 4 of 10 patients with emboli and 0 of 6 without. Thus, LV thrombi that project into the lumen and have increased mobility are more likely to embolize than those without these characteristics.

Adult↗
PubMed1984

Diagnosis of pulmonic regurgitation by contrast echocardiography.

In order to determine whether pulmonic regurgitation (PR) can be reliably diagnosed using contrast echocardiography, we studied 24 subjects using echocardiography during intravenous injections of 5% dextrose solution. Twelve were without PR, and twelve had PR (10 after intracardiac repair of tetralogy of Fallot, one after a Brock procedure for pulmonic stenosis, and one after insertion of a right ventricle-pulmonary artery conduit for pseudo truncus arteriosus). Two blinded independent observers correctly diagnosed PR in all patients when it was present, and correctly excluded it in 11 of 12 of the patients without PR. They disagreed in one patient who had an unusual contrast pattern during diastole. Four postoperative patients had PR by contrast echocardiography despite the absence of a cardiac murmur at the time of their study. We conclude that contrast echocardiography is a safe, simple, sensitive, and specific method for diagnosing PR. Some methodologic suggestions and limitations of the method are discussed.

Adolescent↗