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Biomedical subjects

R A Slutsky

Publications and source records attributed to R A Slutsky.

At least 55 records · Page 3Linked to original sources
PubMed1984

Extravascular lung water: effects of using ionic contrast media at varying levels of left atrial pressure and during myocardial ischemia.

Intravenous injections of ionic contrast media are widely used in the performance of radiographic techniques. The effects of ionic contrast media on lung water are unclear in the setting of elevated left atrial pressure, particularly in the presence of myocardial ischemia. In this study, we examined the effects of bolus injections of intravenous sodium meglumine diatrizoate (Renografin 76, 1 ml/kg, injected at 20 ml per second) on measures of extravascular lung water (EVLW) at several levels of left atrial pressure and in the presence of myocardial ischemia. Bolus injections of Renografin 76 produced significant increases in EVLW, with similar mean peak increases of approximately 26% EVLW at low (initial pressure less than 3 mm Hg), moderate (approximately 15 mm Hg), and elevated left atrial pressures (approximately 25 mm Hg). At matched pressures, the peak change in EVLW in the ischemic dogs was +45%, +60%, and +70%, respectively (all P less than .001 vs. the nonischemic dogs). Thus, use of intravenous ionic media precipitated acute transient increases in lung water, which were exaggerated by myocardial ischemia. While the effects were time limited in this experimental model, caution is advised in using intravenous ionic media in patients who have left ventricular dysfunction, particularly if underlying ischemia is present.

Animals↗
PubMed1984

Extravascular lung water in patients with mitral stenosis: relationship to pulmonary capillary wedge pressure and Kerley B lines.

To evaluate the relationship between extravascular lung water, pulmonary capillary wedge pressure, and chest radiographic findings, extravascular lung water (EVLW) was assessed using double indicator-dilution techniques in 34 adult patients with mitral stenosis. Seven patients were studied 6 to 12 months after successful mitral valve replacement. In the 27 preoperative patients, septal lines were found to be indicative of elevated EVLW only in the presence of intravascular congestion. An excellent correlation between EVLW and pulmonary capillary wedge pressure was observed in these patients (r = .81, p less than .001), whereas only a rough correlation between scored radiographic findings and EVLW was observed. Postoperatively, septal lines were invariably associated with normal filling pressures and EVLW. Thus in both preoperative and postoperative mitral stenosis patients, interstitial Kerley B lines are insensitive markers of elevated extravascular lung water in the absence of pulmonary vascular engorgement. This emphasizes the importance of interpreting radiographic findings of extravascular fluid in conjunction with evaluation of the vascular bed in patients with chronic postcapillary hypertension.

Adult↗
PubMed1984

Comparative effects of antihypertensive therapy with guanabenz and propranolol on renal vascular resistance and left ventricular mass.

There is increasing interest in initial therapy of hypertension with sympatholytic agents and the influence of antihypertensive therapy on cardiac and renal function. We treated 26 men with essential hypertension with either guanabenz alone (n = 14) or propranolol alone (n = 12) and assessed blood pressure and renal perfusion before and after 5-7 weeks of treatment. Cardiac performance was evaluated for the guanabenz-treated patients. Both drugs substantially reduced blood pressure without weight gain. During guanabenz therapy, glomerular filtration rate and renal blood flow were preserved, with a fall in renal vascular resistance (from 12,100 +/- 1,500 to 9,300 +/- 1,190 dyne X s X cm-5, p less than 0.01). Propranolol decreased glomerular filtration rate (from 95 +/- 11 to 70 +/- 6 ml/min, p less than 0.05) without significant change in renal blood flow or renal vascular resistance. In guanabenz-treated patients, there was a decline in left ventricular mass (from 290 +/- 23 to 257 +/- 14 g, p = 0.067). Thus, both agents are effective initial therapy in hypertension. Guanabenz treatment also was associated with reduced renal vascular resistance and left ventricular mass.

Adult↗
PubMed1984

In vitro magnetic relaxation times of the ischemic and reperfused rabbit kidney: concise communication.

To assess the effects of renal ischemia and reperfusion on in vitro magnetic relaxation times (T1 = magnetization recovery, T2 = spin echo), we evaluated the spectroscopic characteristics of the renal cortex from 25 rabbits. Eight served as controls (Group 1), nine had one renal pedicle ligated for 1 hr (Group 2), and eight (Group 3) were occluded for 1 hr and reperfused for 30 min. For intra-animal comparison purposes, % H2O content, T1 (msec), and T2 (msec) of the ischemic (reperfused) kidney were normalized to the values from the normal kidney within the same animal. Renal ischemia consistently increased water content, which was exaggerated by reperfusion. In association with ischemia, T1 fell, and with reperfusion T1 lengthened. T2 increased with ischemia and declined from the peak ischemic effects with reperfusion.

Animals↗
PubMed1984

Thallium scintigraphy in experimental toxic pulmonary edema: relationship to extravascular pulmonary fluid.

Pulmonary fluid volumes (PBV = lung blood volume; EVLW = extravascular lung water) were examined to define the effects of oleic acid injury and then to examine the relationship between edema formation and accumulation of pulmonary thallium. In six dogs, pulmonary fluid compartments were monitored during the induction of pulmonary injury by oleic acid (0.15 cc/kg i.v.). By 30 min after the injection, EVLW had doubled (p less than 0.01); it continued to increase slowly for 180 min, whereas PBV declined. In six anesthetized dogs, we made similar measurements in an identical preparation and compared pulmonary fluid volumes with pulmonary counts derived from sequential thallium (1-1.3 mCi) scintigrams obtained after the injection of oleic acid (0.12-0.15 ml/kg). Measures of EVLW and PBV were obtained sequentially along with thallium scintigrams. There was a linear relationship between EVLW and pulmonary counts alone, or when pulmonary counts were normalized to myocardial activity. We conclude that sequential thallium scintigrams provide useful information about the degree of change of EVLW over time in a model of noncardiogenic pulmonary edema.

Animals↗
PubMed1984

Pulmonary edema formation after myocardial infarction and coronary reperfusion: intravascular and extravascular pulmonary fluid volumes. IV.

Two studies were performed to assess the importance of coronary reperfusion on pulmonary capillary endothelial permeability in 34 anesthetized dogs. The response of intravascular pulmonary blood volume (PBV) and extravascular lung water (EVLW) was examined using indicator-dilution and postmortem (wet weight/dry weight) techniques. In the first study, six dogs served as sham controls, seven were occluded (LAD) for 45 min, and seven occluded for 45 min and reperfused for 15 min. While PBV was similar in each group, EVLW was greater in the reperfused than nonreperfused dogs (9.5 +/- 0.7 cc/kg vs 8.1 +/- 0.8 cc/kg; P less than .05), and both occluded groups were greater (P less than .01) than the control animals (7.0 +/- 1.0 cc/kg). Similar trends in postmortem wet weight/dry weight data were observed when compared with the in vivo EVLW data. In a second study of 14 open-chest dogs, an LAD ligation was held for 45 min in 14 dogs. In seven dogs, reperfusion was allowed for 15 min. A left atrial (LA) balloon was then inflated in all 14 dogs, increasing left atrial pressure to 25 mmHg in each dog for 90 min. Once again, PBV was similar in both groups, but EVLW was greater at the matched level of LA pressure elevation (14.6 +/- 3.2 cc/kg nonreperfused vs 18.7 +/- 4.1 cc/kg reperfused dogs; P less than .01). Again, postmortem data confirmed these data. Thus, we conclude coronary occlusion accelerates EVLW formation independent of LA pressure. Edema formation is worsened by coronary reperfusion, suggesting that the washout of myocardial toxins from the ischemic myocardium alters endothelial permeability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Comparison of digital intravenous ventriculography with direct left ventriculography for quantitation of left ventricular volumes and ejection fractions.

Digital images of the left ventricle obtained at 30 frames/second from continuous fluoroscopy after intravenous injection of contrast medium (digital intravenous ventriculography) were used to estimate left ventricular (LV) volumes and ejection fraction with use of several techniques for identifying the ventriculographic silhouette. The digital technique was compared with direct contrast left ventriculography in 26 patients undergoing diagnostic cardiac catheterization. End-diastolic and end-systolic volumes calculated from digital intravenous and direct left ventriculograms were obtained with use of a standard area-length formula. Both end-diastolic volume (EDV) (r = 0.88, y = 1.06x - 17.1 ml) and end-systolic volume (ESV) (r = 0.89, y = 0.96x + 0.43 ml) determined from digital intravenous ventriculography (mask mode images) correlated closely with those obtained by direct left ventriculography. Combining the EDV and ESV to define the relation between the 2 techniques yielded an even closer correlation (r = 0.96). There was also good correlation between the 2 techniques for measurement of ejection fraction (r = 0.81, standard error of the estimate 6.7%). Measurements from direct left ventriculography were frequently invalidated by ventricular arrhythmias during the time of opacification of the left ventricle; this was rarely the case for digital intravenous ventriculography. It is concluded that area-length estimates of LV volumes and ejection fraction can be accurately obtained from digital processing of fluoroscopic LV images after intravenous injection of contrast medium.

Arrhythmias, Cardiac↗
PubMed1983

Radionuclide analysis of peak filling rate, filling fraction, and time to peak filling rate. Response to supine bicycle exercise in normal subjects and patients with coronary disease.

Using gated equilibrium radionuclide angiography, variables of diastolic filling were analyzed at rest and during supine bicycle exercise in normal subjects (Group 1, n = 18), coronary patients with normal resting ejection fractions (Group 2, n = 26), and coronary patients with reduced resting ejection fractions (Group 3, n = 8). Indexes analyzed were peak filling rate and filling fraction during the first third of diastole. At rest, the peak filling rate was significantly lower in coronary patients than in normal subjects (3.18 +/- 0.82 end-diastolic volume [EDV]/s in Group 1 versus 2.41 +/- 0.66 EDV/s in Group 2, p less than 0.005; and 1.34 +/- 0.26 EDV/s in Group 3, p less than 0.001 versus Group 1). These differences persisted at peak exercise. Coronary patients also had significantly lower filling fractions at rest and during exercise than did normal control subjects. The time from end-systole to peak filling rate was longer at rest in patients in Group 2 (203 +/- 52 ms) than in subjects in Group 1 (172 +/- 50 ms, p less than 0.025). This remained true when the time to peak filling was normalized by the R-R interval. Although the exercise time to peak filling was longer in coronary patients in both Groups 2 and 3 than in Group 1, these differences were not apparent when the interval was normalized by the R-R interval. Thus, abnormalities in peak filling rate and filling fraction exist in patients with coronary disease both at rest and during exercise, but large overlaps exist between normal and coronary patients. Caution is advised in comparing the timing of events during diastole because apparent group differences may be related in part to rest or exercise heart rate.

Adult↗
PubMed1983

Pulmonary blood volume: analysis during exercise in patients with left ventricular dysfunction.

Recent reports have demonstrated substantial increases in pulmonary activity during radionuclide stress exercise studies in patients with coronary heart disease. These studies have shown that the degree of the increase reflected the severity of the underlying disease. We studied the effects of supine exercise on systolic function and pulmonary activity in ten normal control subjects and 20 patients with congestive cardiomyopathy (12 ischemic and 8 idiopathic). Ejection fraction rose in the normals (P less than 0.001), end-diastolic volume increased slightly but significantly (P less than 0.05), and pulmonary activity rose by less than 16%, (mean 10%) while cardiac output increased by 162%. On the other hand, the myopathy patients demonstrated a small increase in cardiac output, (+49%) with a more substantial increase in pulmonary activity (+25%, P less than 0.05 vs normals). In these patients, ejection fraction did not change during exercise, while end-diastolic and end-systolic volumes rose. In the myopathy patients, the cause for an increase in cardiac output was a rise in heart rate, with little change in stroke volume. We conclude that pulmonary activity rises in myopathy patients to a greater extent than in normal controls. This probably reflects the greater elevation in filling pressures these patients need to maintain forward cardiac output.

Adult↗
PubMed1983

Cardiac imaging with digital subtraction angiography.

Central cardiovascular anatomy and function have been evaluated with intravenous digital subtraction angiography (DSA). The subtraction techniques used for studying the left ventricle (LV) were mask mode, time interval difference and functional subtraction. Aside from contrast enhancement, a major use of digital fluoroscopy for cardiac applications has been computer-assisted quantitative analysis of LV dimensions and function. Left ventricular volumes and wall thickness determined from DSA studies have correlated closely with direct left ventriculograms and sonocardiometry measurements in patients and animals, respectively. Measurements of segmental LV contraction with DSA correlated closely with direct left ventriculography in normal patients and patients with coronary artery disease. The sensitivity of intravenous DSA for detecting significant coronary artery disease was increased by performing DSA immediately after increasing the myocardial oxygen demands by atrial pacing. The advantages and disadvantages of DSA in relation to other semi-or non-invasive imaging modalities are discussed.

Angiocardiography↗
PubMed1983

Relationship of radionuclide indexes of cardiac function during interventions: volume loading, afterload stress, exercise, and pacing.

We compared three radionuclide indexes of cardiac function: (1) the ejection fraction (EF), (2) the mean ejection rate (ER), and (3) the mean velocity of circumferential fiber shortening (MVCF) during volume loading, phenylephrine hydrochloride stress, exercise, and atrial pacing. All behaved in a similar (linear) fashion, allowing appropriate hemodynamic conclusions to be drawn using either index. During atrial pacing, the ejection fraction declined, when velocity indexes increased--suggesting that the ejection fraction may not be a suitable index to characterize alterations in inotropic state during rapid alterations in heart rate, particular in the absence of angina pectoris. This may result from the reductions in cardiac volume for the duration of pacing, where the velocity index is preserved. In most circumstances excluding atrial pacing, ejection fraction during interventions is an adequate index of the change of myocardial contractile state. Overall, radionuclide angiography is an excellent technique to characterize acute hemodynamic interventions, with ejection fraction, in general, the simplest and most reliable of cardiac indexes during stress interventions.

Adult↗
PubMed1983

Radionuclide analysis of ejection time, peak ejection rate, and time to peak ejection rate: response to supine bicycle exercise in normal subjects and in patients with coronary heart disease.

Using equilibrium radionuclide angiography, we evaluated the ejection time (ET), peak ejection rate (PER), and time to peak ejection rate (TTp) at test and during supine bicycle exercise in 39 subjects, divided into three groups: group 1 = 13 normal subjects; group 2 = 10 patients with a previous infarction (MI); and group 3 = 16 patients with coronary disease without a previous MI. Normal subjects had greater ejection fractions and PERs than the other two groups at rest or peak exercise (p less than 0.05). PER was no more useful than ejection fraction in identifying cardiac dysfunction at either rest or exercise. The time of its occurrence varied with the group studied, and was slightly but significantly later in systole in groups 2 and 3 when compared to normals (p less than 0.05), though substantial overlap between groups occurred. During exercise, absolute ET shortened in all groups, but actually increased as a function of the R-R interval. The time to peak ejection rate (normalized for the R-R interval) was greater in the noninfarct group (group 3) patients (p less than 0.05) when compared to the group 1 or group 2 individuals at peak exercise. In conclusion, equilibrium radionuclide angiography is a useful technique for the quantification and characterization of events during systole, and is capable of providing information on the timing of events during ejection. Tardokinesis, or the delay of ventricular ejection, is not seen in the response of global indices of left ventricular function to exercise stress. While global early systolic indexes may not detect regional dyssynchrony, their timing during stress may occasionally aid in discerning the presence of cardiac dysfunction.

Adult↗
PubMed1983

Pulmonary blood volume: relationship to changes in left ventricular end-diastolic pressure during atrial pacing.

Little data exist about the relationship between changes in cardiac end-diastolic pressure and changes in pulmonary blood volume. To assess this relationship, we studied 11 patients with coronary heart disease during atrial pacing in an attempt to produce multiple pressure-volume points. During catheterization, we obtained Millar pressure recordings of end-diastolic pressure along with equilibrium radionuclide angiograms. Cardiac output, ejection fraction, and pulmonary blood volume were obtained by means of recently validated radionuclide techniques. During pacing, substantial changes in pulmonary blood volume occurred only with marked increase in end-diastolic pressure volume (greater than or equal to 15 mm Hg) and rarely exceeded 15% of control pulmonary blood volume. Cardiac output did not change, while ejection fraction declined during pacing. There was a fair correlation between the absolute change in pulmonary activity (or pulmonary blood volume) or the percentage of change in pulmonary activity over the control value with end-diastolic pressure when all the data points were evaluated (n = 74, r greater than 0.70). However, the scatter in the data precluded making accurate estimates of pressure changes from changes in radionuclide volume changes. We conclude that large changes in cardiac filling pressure must occur during atrial pacing, where cardiac output does not change, before visible pulmonary blood volume changes occur. This may limit the extrapolation of presumed pressure changes from known pulmonary blood volume when changes are small.

Blood Pressure↗
PubMed1983

Pulmonary circulation time: comparison of mean, median, peak, and onset (appearance) values using indocyanine green and first-transit radionuclide techniques.

To assess the difference between a variety of mathematical methods for assessing pulmonary transit time, we evaluated 11 acutely anesthetized and instrumented mongrel dogs at a control stage and then during infusions of isoproterenol or phenylephrine, or after the induction of ischemia. Green-dye optical density curves were obtained to evaluate a variety of pulmonary circulation times. Mean transit time, median time, peak time, and onset time all correlated well (r greater than or equal to 0.93), with the mean time being the longest, followed by the median time (4% less than the mean time, p less than 0.05), peak time (15% less than the mean time p less than 0.01), and onset or appearance time (49% less than the mean time, p less than 0.001). In the 34 available data points the mean time averaged 4.67 +/- 1.7 seconds, the median time averaged 4.47 +/- 1.74 seconds, the peak time averaged 3.98 +/- 1.7 seconds, and the onset time averaged 2.27 +/- 1.43 seconds. Similar results were obtained from the first-pass radionuclide angiograms from 17 adult male subjects. We conclude that median, peak, and onset times are reasonable though predictably shorter approximates of mean pulmonary transit time. They may be utilized during interventions (particularly when alternative counting methods are planned, as with radionuclide or possibly digital angiographic techniques) as guides to changes in the pulmonary circulation.

Animals↗
PubMed1983

Hemodynamic and electrocardiographic effects in man of a new nonionic contrast agent (iohexol): advantages over standard ionic agents.

Iohexol is a new, nonionic contrast material that has been shown in animal studies to hold great promise as an agent for coronary arteriography and ventriculography with fewer adverse hemodynamic effects than standard ionic media. At present, it has not been studied systematically in man. Fifty patients referred for elective cardiac catheterization were randomized to receive either iohexol or meglumine sodium diatrizoate (Renografin-76). Both operator and patient were blinded as to which agent was being used. Hemodynamic variables measured were pulmonary artery wedge pressure and systemic blood pressure. In addition, the following electrocardiographic indexes were evaluated: S-T segment shifts, changes in Q-T interval, changes in T-wave amplitude, and changes in heart rate. These variables were measured after left ventriculography and after both left and right coronary arteriography. Both iohexol and sodium meglumine diatrizoate produced small transient elevations in pulmonary artery wedge pressure. Systemic hypotension occurred with both agents but was more profound and longer-lasting with sodium meglumine diatrizoate. Iohexol injection resulted in no electrocardiographic changes, whereas sodium meglumine diatrizoate produced marked Q-T prolongation, as well as changes in T-wave amplitude and heart rate. Iohexol was well tolerated by the patients, and radiographic opacification was good to excellent in all cases. Thus, iohexol produces fewer deleterious hemodynamic and electrocardiographic changes than sodium meglumine diatrizoate when studied in a typical adult population requiring diagnostic cardiac catheterization. This favorable preliminary experience in man has potential widespread importance because of the large number of patients undergoing angiographic procedures.

Aged↗
PubMed1983

Quantitative phase analysis of exercise radionuclide left ventriculography in normals and patients with coronary artery disease.

Using multigated radionuclide ventriculography (RNV), the left ventricular (LV) phase histogram (PH) was used to quantitate LV synchrony at rest and at submaximal and maximal supine exercise in 10 normal and 10 coronary (CAD) patients. Each LV PH was obtained by masking the phase image with an LV region, generated semiautomatically and modified if necessary to minimize ambiguity of LV delineation. The shape and spread of each histogram was characterized by its standard deviation (SD) and skewness (SK). Normals had a tight resting PH with slight negative skewness (SD = 9.06 +/- 0.22 (mean +/- SEM; SK = -0.53 +/- 0.05). CAD patients had a wider resting PH with a larger SD and a significantly more positive skewness reflecting greater contractile asynchrony (SD = 16.53 +/- 2.26; SK = 0.35 +/- 0.22). With exercise the PH distribution for the normals remained tight (SD = 8.1 +/- 0.24) while SK changed little (SK = -0.29 +/- 0.04). In contradistinction, with exercise CAD patients markedly increased the spread of their LV PH (SD = 27.42 +/- 3.77) and increased the number of late pixels (SK = 0.75 +/- 0.15). It is concluded that quantitative PH analysis is a useful adjunct for the analysis of regional asynergy during resting or exercise radionuclide left ventriculography.

Coronary Disease↗
PubMed1983

The accuracy of radionuclide ventriculography in the analysis of left ventricular ejection fraction.

To assess the reliability of using ejection fraction values derived from gated blood pools scans as a way to classify patients, we reviewed 76 radionuclide studies. Each study was processed in 10 different ways (varying or fixed left ventricular region of interest in association with 5 different backgrounds), and compared with contrast ventriculograms performed within one week of the radionuclide study. Correlation values with contrast results varied from 0.76 to 0.94 (mean 0.84 +/- 0.06, +/- 1 SD), and linear fit slopes varied from 0.39 to 0.90 (mean 0.75 +/- 0.15). Based on contrast results, patients were divided first into four groups (severely reduced, reduced, normal, and high ejection fractions). Predictive accuracy of the radionuclide estimates for these four groups was poor, ranging from 0.39 +/- 0.08 to 0.82 +/- 0.06%. Sensitivity was somewhat better (range 0.53 +/- 0.11 to 0.78 +/- 0.08%), and specificity better yet (0.78 +/- 0.08 to 0.95 +/- 0.02%). The results were better with techniques resulting in higher correlation values, and further improved when patients were regrouped into two populations (normal or reduced), though 90% of subjects were correctly identified only when correlation values exceeded 0.90. We conclude that care must be taken in the identification of patients using radionuclide angiography who have normal and abnormal left ventricular function; it can be done with confidence only when linear fits with contrast ventriculographic results have high correlation coefficients. Stratification attempts should be reduced to a minimum, as multiple population subgroups result in substantial patient mislabeling.

Adult↗