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Biomedical subjects

R S Meltzer

Publications and source records attributed to R S Meltzer.

104 records · Page 6Linked to original sources
PubMed1979

Diagnosis of left ventricular thrombi by two-dimensional echocardiography.

Sixteen patients had two-dimensional echocardiographic diagnosis of the presence or absence of left ventricular thrombi and anatomical, radiological, or clinical confirmation of the diagnosis. Eleven patients had positive diagnoses, which were confirmed in 10 and possibly incorrect in one. Five other records were reviewed because the patients had undergone aneurysmectomy after two-dimensional echocardiograms: three were true negative and two were false negative studies.

Adult↗
PubMed1978

Atypical ventricular tachycardia as a manifestation of disopyramide toxicity.

An unusual ventricular tachyarrhythmia developed in a 57 year old woman with recurrent ventricular tachycardia and toxic disopyramide plasma concentrations. The rhythm was similar to the patient's previous ventricular tachycardia, but the rate was slower and the QRS complex was markedly widened, mimicking the electrocardiographic changes associated with electrolyte abnormalities. Disopyramide, which has electrophysiologic properties similar to those of quinidine, probably caused the arrhythmia and should be added to the list of drugs associated with atypical ventricular tachycardia.

Administration, Oral↗
PubMedDate not supplied

Digital subtraction myocardial contrast echocardiography: design and application of a new analysis program for myocardial perfusion imaging.

Myocardial contrast echocardiography may provide important physiologic information on myocardial perfusion. Most current analysis programs use manual frame grabbing and selecting of the area of interest. This is time-consuming and not highly reproducible. A system for automatic analysis of myocardial contrast echocardiographic studies was developed and evaluated. The program acquires an electrocardiographically gated sequence of end-diastolic images with a frame grabber in a personal computer. The baseline image is subtracted and the videodensity versus time contrast curve parameters are calculated on-line. Fast color-coded analysis is done automatically with a running square window that covers the entire image. A second mode of contrast analysis allows manual selection of multiple regions of interest. The program was evaluated with contrast echo data from open-chest dogs and two demonstrative patients. This myocardial contrast analytic package is an inexpensive, rapid, flexible, convenient, and reproducible on-line method that facilitates myocardial contrast echocardiographic analysis.

Albumins↗
PubMedDate not supplied

Quantitative myocardial ultrasonic integrated backscatter measurements during contrast injections.

We and others have shown that normal myocardium exhibits 4 to 5 dB diastolic-to-systolic cyclic variation (CV) of integrated backscatter. To investigate the effect of intramyocardial contrast on integrated backscatter, we injected 5% sonicated albumin, containing microbubbles in the range of 5 microns in diameter, into the left atrium in nine open-chest dogs. The dogs were anesthetized and placed in the right lateral decubitus position on a specially designed table with a cutout allowing ultrasound imaging from below. Ultrasonic data was obtained from the right precordium by use of a prototype M-mode integrated backscatter system implemented in a commercially available two-dimensional system. Usable data were obtained in eight of nine dogs. Integrated backscatter increased up to 13 dB after contrast injections. There was a significantly decreased CV of integrated backscatter during myocardial contrast in all eight dogs. The mean level of CV of integrated backscatter for the eight dogs decreased from 4.7 dB (530 beats analyzed) without contrast to 2.8 dB during contrast (436 beats analyzed). There was a trend to greater CV at higher levels of contrast. Septal excursion, as measured by M-mode echocardiography simultaneously with integrated backscatter by the same ultrasound beam, was similar with and without contrast (mean 8.2 vs 8.3 mm). Thus left atrium contrast injection produces quantitatively measurable integrated backscatter effects. Cyclic variation of integrated backscatter decreases with contrast. However, at higher contrast levels the decrease tends to be smaller. These effects should be considered during quantitative tissue characterization and myocardial contrast studies.

Albumins↗
PubMedDate not supplied

Myocardial perfusion studies by contrast echocardiography.

Determination of regional myocardial blood flow may provide clinically valuable information about ischemia, risk area, and the effect of angioplastic, surgical, and pharmacologic interventions. Contrast echocardiography, with use of prepared microbubbles of 4 to 8 microns size, graphically demonstrates perfusion characteristics in the catheterization laboratory. Analysis and interpretation of this data and the creation of contrast materials that will demonstrate myocardial perfusion after intravenous injection are some of the next challenges in these techniques.

Contrast Media↗
PubMedDate not supplied

Normal values of prosthetic valve Doppler echocardiographic parameters: a review.

Doppler echocardiography plays an important role in the evaluation of patients with prosthetic valves. The evaluation of flow velocities across prosthetic valves is more complicated compared with native valves, and flow velocities are specific for various types, positions, and sizes of prostheses. Because all prosthetic valves are at least mildly stenotic and a significant proportion is regurgitant, information regarding normally functioning prosthetic valves is important. Eighteen studies resulting in data on 1105 patients with normally functioning prosthetic valves were reviewed. Significant differences among the various types and sizes of prosthetic valves were found in both the aortic and mitral positions. The results are summarized in tables and figures that can be used for reference in a clinical laboratory.

Blood Flow Velocity↗
PubMedDate not supplied

Food and Drug Administration ultrasound device regulation: the output display standard, the "mechanical index," and ultrasound safety.

The Food and Drug Administration has recently revised its guidelines regarding acoustic output on diagnostic ultrasound equipment to allow a new track for manufacturers to achieve approval to market diagnostic ultrasound equipment. It would move for the first time toward regulating instrumental output based on scientific bioeffect data. It would allow increased instrumental output in certain modes and at the same time mandate on-screen labeling of a "thermal index" or "mechanical index," coupled with a user education program on the significance of these indexes. The increased instrumental output allowed by these new guidelines may benefit adult echocardiography by allowing slightly more penetration and higher frequency/better resolution. However, a tradeoff is that echocardiographers need to understand more about how to perform an examination to decrease unnecessary patient exposure to ultrasound and more about ultrasound bioeffects, such as the theoretical potential for cavitation-related adverse effects in certain circumstances.

Equipment Safety↗
PubMedDate not supplied

Case report: Antemortem diagnosis of central nervous system strongyloidiasis.

Strongyloidiasis is usually a benign illness confined to the gastrointestinal tract. However, dissemination (hyperinfection syndrome) may occur, particularly in patients with impaired cell-mediated immunity. The diagnosis of hyperinfection syndrome is often made postmortem, and mortality is high, even when the disease is recognized during life. Central nervous system involvement with Strongyloides stercoralis has previously been recognized in only a few cases at postmortem examination, and in one case antemortem. We describe a patient with disseminated strongyloidiasis in whom central nervous system involvement was diagnosed antemortem. This patient developed multiple bacterial and fungal systemic and central nervous system infections as a complication of disseminated strongyloidiasis. The natural history of the disease in man, factors predisposing to dissemination, immunologic aspects of helminthic infection, and treatment modalities are discussed.

Animals↗
PubMedDate not supplied

Inaccuracy of Doppler estimates of pulmonary artery pressure using pulmonary flow acceleration time.

Pulsed Doppler echocardiography was used to estimate mean pulmonary artery pressure (PAP), mean pulmonary artery wedge pressure PAWP) and the changes in PAP and PAWP following intervention in an unselected population composed of 60 patients undergoing routine diagnostic cardiac catheterization. Simultaneous Doppler and strain gauge manometry recordings of PAP and PAWP were interpreted by independent observers in a blinded fashion. A first set of measurements was obtained before left ventricular angiography and a second soon after the injection of contrast dye. The mean Doppler PAP and PAWP were derived from acceleration time and calculated using previously published regression equations: PAP = -0.45 x AcT + 79, PAWP = 57 - 0.39 x AcT. At rest, PAP measurements by strain gauge manometry ranged from 13 to 45 mmHg with a mean of 24 +/- 10 (one standard deviation); PAWP ranged from 2 to 40 mmHg with a mean of 15 +/- 6. Following left ventricular angiography, the PAP ranged from 18 to 50 mmHg with a mean of 29 +/- 7; PAWP ranged from 6 to 45 mmHg with a mean of 20 +/- 7. The values obtained by pulsed Doppler before and after intervention correlated poorly with those obtained by strain gauge manometry (r = 0.09 and 0.26 for PAP; r = 0.03 and 0.25 for PAWP).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗