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R Slutsky

Publications and source records attributed to R Slutsky.

45 records · Page 3Linked to original sources
PubMed1979

Left ventricular volumes by gated equilibrium radionuclide angiography: a new method.

To compare radionuclide end-diastolic (EDV) and end-systolic (ESV) volumes with angiographic volume, we studied 52 patients with equilibrium radionuclide angiography using 99mTc-human serum albumin within 48 hours of contrast angiography. Each RR interval was divided into 20--28 equally timed frames and a time-activity curve generated. End-diastolic counts were taken at the early peak of the curve and end-systolic counts at its nadir. Counts were divided by the total number of processed heart beats and normalized for: 1) dose per body surface area; 2) plasma volume; and 3) counts/ml of plasma. A cardiac phantom was developed and serial volumes were studied using a normalization factor. Radionuclide values were expressed as dimensionless units and compared with either biplane angiographic volumes (in the patient studies) or known phantom volumes. Good correlations were obtained with methods 1 and 2 in 35 patients (r greater than 0.84), but the best correlation was obtained in 17 patients when normalization for counts/ml of plasma was used (r = 0.98; y = 0.255 x -0.121). The standard error of the estimate (SEE) was +/- 11.5 ml for EDV and +/- 7.3 ml for ESV. The phantom study also showed an excellent correlation (r = 0.99), with a SEE of +/- 6.5 ml. We conclude that a radionuclide method independent of geometric assumptions can be used to estimate left ventricular volume in man.

Adult↗
PubMed1979

Reproducibility of ejection-fraction determinations by equilibrium radionuclide angiography in response to supine bicycle exercise: concise communication.

Sixteen patients with stable, chronic coronary artery disease were studied twice within and average of 15 days to evaluate the reproducibility of ejection fraction (EF) determined by equilibrium radionuclide angiography (EQ) at rest, during supine bicycle exercise (ex), and in the recovery period (rec). Following injection of 20--25 mCi of Tc-99m-tagged human serum albumin, data were analyzed for 2-min periods at rest, during several stages of exercise (submax, max), and during recovery (rec1 = minutes 2 + 3, rec2 = minutes 9 + 10). Each patient reached similar (heart rate) X (blood pressure) products in the two studies: 21280 +/- 5200 compared with 20390 +/- 4140 mmHg/min. Mean EFs for the first and second studies were: at rest (53.0 +/- 10.8)%, 52.5 +/- 10.4)% (r = 0.95; submax ex (51.4 +/- 12.0)%, (52.1 +/- 12.8)%, (r = 0.91); max ex (50.6 +/- 12.6)%, (51.6 +/- 12.9)% (r = 0.97); rec1 (62.7 +/- 11.6)%, (62.4 +/- 12.2)% (r = 0.95); rec2 (55.5 %/- 10.8)%, (57.2 +/- 11.7)% (r = 0.91). In stable patients, the reproducibility of EF determined by EQ is excellent during rest, supine bicycle exercise, and recovery from exercise.

Adult↗
PubMedDate not supplied

Pulmonary blood volume: correlation of equilibrium radionuclide and dye-dilution estimates.

In fifteen prospective patients with aortic stenosis undergoing transseptal cardiac catheterization, dye-dilution and count-based estimates of pulmonary blood volume (PBV) were performed. Three radionuclide methods were evaluated. Two were based on electrocardiogram (ECG)-gated imaging of the thorax, where pulmonary counts (PC) were corrected for frame-time, venous radioactivity, and either (1) the number of processed heart beats or (2) the total duration of acquisition. The third method involved ungated frame mode acquisitions, where PC were corrected for the duration of acquisition and the venous activity. PC (per channel element) were derived from manual assignments of the right lung. All methods correlated well with standard dye-dilution techniques (r greater than 0.82), though at greater volumes it was clear that count-based methods underestimated the dye-dilution values. In five acutely instrumented, anesthetized dogs, radionuclide (ungated formula) and dye-dilution estimates of PBV were made during multiple interventions (19 data points). The five control count volumes as well as the 14 separate intervention points correlated well (r greater than 0.89). It is concluded that PC from equilibrium blood pool images reflect PBV and that induced changes in PC can be utilized as a reflection of changes in PBV.

Adult↗
PubMedDate not supplied

Pulmonary blood volume: the response to afterload in normal subjects and patients with previous myocardial infarction.

To analyze the effects of acute elevations in arterial blood pressure on pulmonary blood volume (PBV) and left ventricular function, eight normal controls and ten patients with previous myocardial infarctions were studied using equilibrium radionuclide angiography during the infusion of phenylephrine. Radionuclide estimates of PBV did not change significantly in the control subjects (48 +/- 20 units at rest, 53 +/- 28 units after administration of atropine, and 47 +/- 20 units at the peak elevation of pressure), though cardiac output rose and pulmonary transit time declined (P less than .05). In infarct patients, resting PBV was similar to that of normals at rest (44 +/- 12 vs. 48 +/- 20, p = not significant). However, it rose significantly at the peak elevation of arterial pressure (55 +/- 12 units, P less than .05 vs. control). Transit time was greater in the patients at rest (22 +/- 15 units vs. 14 +/- 7 units in controls, P less than .01), and, unlike transit time of normals, did not decline with pressure overhead. At any level of afterload-induced increases in end-diastolic volume or decreases in ejection fraction, PBV was greater in the patients than in normals. This suggests that, while the absolute response of cardiac volume and ejection fraction to pressure overload may be quantitatively similar in normals and infarct patients, This is not mirrored by changes in PBV and transit time. In all likelihood, elevations in cardiac filling pressures and pulmonary distending pressures occur in the infarct patients. Increases in PBV may be a noninvasive reflection of both the development of incipient congestive heart failure and reduced myocardial compliance in infarct patients. In this way, pressure overload stress may be a useful technique to prospectively categorize patient populations subject to higher incidences of congestive failure.

Adult↗
PubMedDate not supplied

Automatic analysis of left ventricular ejection fraction using stroke volume images.

The purpose of this study was to analyze, validate, and report on an automatic computer algorithm for analyzing left ventricular ejection fraction and to indicate future applications of the technique to other chambers and more advanced measurements. Thirty-eight patients were studied in the cardiac catheterization laboratory by equilibrium radionuclide ventriculography and concurrent contrast ventriculography. The temporal and spatial behavior of each picture element in a filtered stroke volume image series was monitored throughout the cardiac cycle. Pixels that met specific phase, amplitude, and derivative criteria were assigned to the appropriate chamber. Volume curves were generated from regions of interest for each chamber to enable calculation of the left ventricular ejection fraction. Left ventricular ejection fractions showed a good correlation (r = 0.89) between the two techniques. Ejection fractions ranged between 0.12 and 0.88, showing a wide range of application. It is concluded that automatic analysis of left ventricular ejection fraction is possible using the present algorithm and will be useful in improving the reproducibility and providing more accurate information during exercise protocols, pharmaceutical interventions, and routine clinical studies.

Cardiac Output↗