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Biomedical subjects

H Feigenbaum

Publications and source records attributed to H Feigenbaum.

At least 217 records · Page 12Linked to original sources
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Intracardiac echocardiography-guided biopsy of intracardiac masses.

A 69-year-old man diagnosed with lung cancer had a transesophageal echocardiogram performed because of suspicion of intramyocardial tumor. The transesophageal echocardiogram confirmed the presence of both a right and left atrial mass. The lung cancer was believed to be potentially resectable if this mass did not represent tumor; therefore, biopsy of the intracardiac mass was requested. Intracardiac ultrasound was used to guide the biopsy procedure. Using intracardiac ultrasound guidance, a successful biopsy was performed that revealed the presence of tumor cells.

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Pharmacologically induced myocardial ischemia: a comparison of dobutamine and dipyridamole.

The purpose of our study was to compare the ability of dobutamine and dipyridamole infusion to induce myocardial ischemia. In a population of 16 anesthetized open-chest swine, a coronary artery stenosis sufficient to abolish the hyperemic response to a 15-second total occlusion was created. Heart rate, systolic blood pressure, and dP/dt were recorded. Myocardial segment shortening was determined by sonomicrometry in all animals. In a subset of seven animals regional myocardial blood flow was measured by injection of radiolabeled microspheres. Dipyridamole was infused according to a high-dose protocol. After a washout period and reestablishment of a baseline state, dobutamine was infused incrementally. There was no significant difference between the baseline states. Dipyridamole did not affect heart rate but did significantly decrease blood pressure and rate-pressure product. Myocardial segment shortening decreased in the ischemic zone by 0.07 +/- 0.08 (p = 0.004). Dobutamine infusion significantly increased heart rate, blood pressure, and rate-pressure product. Myocardial segment shortening in the ischemic zone decreased by 0.17 +/- 0.09 (p < 0.001). Dobutamine decreased blood flow in the ischemic zone relative to baseline. Both dobutamine and dipyridamole infusion resulted in myocardial ischemia. The magnitude of the ischemic response is greater for dobutamine than for dipyridamole.

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Color coding of digitized echocardiograms: description of a new technique and application in detecting and correcting for cardiac translation.

Color coding is a new software application for digitized echocardiograms that displays a reference image of end diastole throughout the cardiac cycle. With color-coded digitized echocardiograms, we determined the frequency of, and corrected for cardiac translation in 21 bicycle stress echocardiograms in patients who were known to be without significant coronary artery disease or wall motion abnormalities. Translation was present in 4%, 40%, and 74% of rest, postexercise, and peak exercise images, respectively, and was noted most frequently in the apical views, 59% of four-chamber views and 40% of two-chamber views. Interobserver and intraobserver agreement for detection of translation was 81% and 86%, respectively. Translation was corrected by shifting digitized images to eliminate transverse displacement of the mitral valve anulus and restore normal basal-to-apical shortening. Ventricular contraction was assessed as normal in 92% of the images in which correction for translation was performed. In the remaining images, poor image quality (3%) and apparent wall motion abnormalities (5%) prevented the studies from being graded as normal. We conclude that color coding of digitized echocardiograms is a useful new technique that can be applied to detect and correct for cardiac translation.

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Digital recording, display, and storage of echocardiograms.

Digital acquisition, display, and storage are new options available for handling echocardiographic images. These types of image management offer many practical advantages and are excellent supplements to standard videotape recordings. For routine M-mode and Doppler studies this digital approach, when combined with videotape, can virtually eliminate the necessity for strip chart recordings. Probably the principal advantage of digital storage techniques is for two-dimensional echocardiography. The continuous loop display is extremely convenient for rapid review, quantitation, and serial studies. When considering the implementation of these techniques, there are many limitations and practical considerations that must be kept in mind. Recording two-dimensional echocardiograms in a continuous loop mode requires that the same number of frames or cells must be used if one wants to display more than one image simultaneously. When creating a continuous loop of a single cardiac cycle, the number of cells and the interval between cells are greatly influenced by the heart rate. One must be able to display simultaneous images with varying heart rates. Last, the number of cells, the resolution, and the gray scale determine the amount of digital information that has to be stored, retrieved, or transmitted. The cost and size of the medium and the speed with which the images can be retrieved or transmitted become factors in how one elects to digitally acquire this information. One approach that has been used, which seems to work quite well in most cases, is to use an eight-cell sequence for two-dimensional echocardiograms. When primarily interested in looking at ventricular function, especially regional wall motion, a 50 msec interval between frames is most appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)

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