Jason Zielonka

An ambulatory ventricular function monitor: Validation and preliminary clinical results

A device for the continuous measurement of left ventricular (LV) function was tested in a series of 34 subjects. The instrument consisted of 2 arrays of radiation sensitive cadmium telluride detectors held in place over the region of the left ventricle and lung by a vest-like garment (hence the name VEST). The VEST electronic instrumentation included analog-to-digital converters, a battery pack, microprocessor and gating device, which were worn in a back pack. Data generated by the VEST, including the digitized average electrocardiogram, RR interval, counts/13 ms in each radiation detector, and time since commencement of data recording, were recorded on a cassette tape recorder every 2 minutes for subsequent analysis. At the conclusion of conventional multigated blood pool imaging, the VEST was positioned and worn by the subjects while supine, standing in place and walking. The correlation of ejection fraction calculated independently from the VEST and scintillation camera data was greater than 0.95. The inter-record reproducibility of the ejection fraction measured by the VEST in sedentary subjects was less than 3%.

Use of radionuclide ventriculography for assessment of changes in myocardial performance induced by disopyramide phosphate

Disopyramide phosphate may precipitate heart failure in susceptible patients with cardiomegaly. To identify those at risk, gated radionuclide ventriculography (RVG) was performed in two groups. Eleven patients without evidence of structural heart disease constituted group 1, and 12 with impaired ventricular function made up group 2. RVG was carried out before and 2 hours after administration of a single 300-mg dose of disopyramide orally. After disopyramide mean left ventricular ejection fraction (EF) decreased in the 12 patients in group 2 (35% to 26%) (p less than 0.01); depression of function was most pronounced in regions with the poorest baseline value. Of the 11 patients in group 1 (mean EF 60%), EF was reduced after disopyramide in only one. Serum levels of drugs were comparable in patients in both groups (3.1 vs. 3.7 micrograms/ml). We conclude that (1) patients with left ventricular dysfunction are particularly susceptible to the depressant effects of disopyramide; (2) RVG is a sensitive technique for detecting disopyramide-induced changes in ventricular performance; and (3) RVG before and shortly after a dose of disopyramide orally may help to identify those patients at high risk.

Overview Of ACR-NEMA Digital Imaging And Communication Standard

This presentation is to outline the American College of Radiology (ACR) and National Electrical Manufacturers Associa-tion (NEMA) Digital Imaging and Communica-tion Standard (ACR-NEMA Digital Imaging and Communication), which is a creation of joint effort of many fine knowledgeable people on the ACR-NEMA Digital Imaging and Communication Standards Committee, especially Allen Edwin and Gwilym Lodwick, Co-Chairman and Laura Murphy, Executive of the Committee. We hope that the ACR-NEMA Standard will be useful in the development of digital diagnostic imaging and medical information.

Effects of acetyl-strophanthidin on left ventricular function and ventricular arrhythmias☆

Digitalis drugs can suppress ventricular arrhythmias. It is uncertain whether this effect results from improved left ventricular (LV) function. We utilized radionuclide scanning techniques to evaluate changes in LV ejection fraction (EF) after an infusion of acetyl-strophanthidin in 43 patients with frequent ventricular premature beats (VPBs) (44 to 2400/hr). Acetyl-strophanthidin suppressed ventricular arrhythmia in 17 patients, but LVEF increased in only six of these patients (57% to 67%), while it was unaltered in 11 patients (28% to 30%). In 26 patients ventricular arrhythmia was not suppressed. Fifteen of these patients had an increase in LVEF (60% vs 71%), while this was unchanged in 11 patients (27% vs 29%). Thus no correlation was observed between the positive inotropic and antiarrhythmic action of acetyl-strophanthidin on ventricular arrhythmia and LVEF. We conclude that the suppression of VPBs by acetyl-strophanthidin is independent of the drugs effects on LV function. Evidence is reviewed suggesting that the antiarrhythmic effect of acetyl-strophanthidin on ventricular ectopic activity is due to its vagotonic action.

Extension Of The ACR-NEMA Digital Interface Communications Standard To Compression Techniques: Status Report

The ACR-NEMA Digital Imaging and Communications Committee established a working group to propose means to incorporate a wide variety of current compression techniques in the framework of the ACR-NEMA Standard for optional use. A draft Standard on compression has been circulated for comment. It proposes methods of allowing the use of public domain techniques, both bit preserving and non-bit preserving, predetermined techniques between devices already aware of the selected algorithm, and specification by the transmitting device of both algorithm and parameters prior to transmitting compression data. This paper will report on details of the proposal and the current status. An example for an allowed compression algorithm, is presented.

The Acr-Nema Exchange Media Standards: Progress And Future Directions

Working Group V of the ACR-NEMA Digital Imaging and Communications Standards Committee has developed a standard for the exchange of ACR-NEMA formatted data on magnetic tape. This standard makes use of the message structure provided in the ACR-NEMA Digital Imaging and Communications Standard (NEMA 300-1985), and formats it in an ANSI standard label and file structure so as to be compatible with one-half inch magnetic tape systems and software which comply with the ANSI standards. The ACR-NEMA magnetic tape standard has evolved since the preliminary information was presented at the SPIE Medicine XIV/PACS IV in 1986. At present, the standard has been circulated for comment, and will soon be balloted. This paper will present the magnetic tape standard in its final form and will also discuss the future direction of the Working Group. The Working Group is strongly considering the use of a media-independent standard for use with the ACR-NEMA message structure so as to accomodate a diverse set of exchange media.