Detection and assessment of severity of regional ischemic left ventricular dysfunction by digital fluoroscopy.
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Animals↗
Biomedical subjects
R A Slutsky
Publications and source records attributed to R A Slutsky.
Digital intravenous ventriculography: analysis and validation of wall thickness changes during ischemia and inotropic stimulation in dogs.
To assess regional ventricular wall thickening, we studied 8 open-chest dogs using digital intravenous ventriculography at a control stage, after subtotal and total coronary occlusion, and then after isoproterenol administration. In 3 dogs, 2 pairs of myocardial thickness crystals were implanted. Correlations of measures of wall thickness and percentage of wall thickening with crystal measures were excellent at the base (r greater than or equal to 0.97) and near the apex (r greater than or equal to 0.97). Four areas of the inferoapical wall muscle were measured: the base, mid-wall, distal wall, and apex. Four chamber dimensions were also examined: the long axis, base decreased with ischemia. At completion occlusion, it was -24.6 +/- 6% at the base, -27.3 +/- 5% at the mid-wall, -27.1 +/- 5% at the distal wall, and -24.7 +/- 5% at the apex. Percent thickening decreased with occlusion, although greater at the base and mid-wall than at the distal wall and apex. With isoproterenol, end-diastolic thickness increased only at the apex, with little change at the base, distal wall, and mid-wall. Percent thickening increased. In general, ischemia produced increases in end-diastolic hemichords with little change in the long axis. Isoproterenol reduced the hemichords, although the long axis did not change. We conclude the digital intravenous ventriculograms can be used to assess changes in wall thickness with high degrees of accuracy. Asymmetric thickening occurred at rest, with ischemia and with inotropic stimulation, being greatest at the apex and least at the base.
Animals↗
Evaluation of the hemodynamic effects of intravenous administration of ionic and nonionic contrast materials. Implications for deriving physiologic measurements from computed tomography and digital cardiovascular imaging.
The effects of intravenous injection of an ionic contrast material (Renografin-76 [meglumine sodium diatrizoate]) on left ventricular pressure, internal diameter, and wall thickness, and on coronary and femoral hemodynamics were compared with those of a hydrolytically stable nonionic contrast material (iohexol). Renografin-76 caused drastic biphasic changes in left ventricular pressure and dp/dt (rate of change of left ventricular pressure), and moderate changes in end systolic dimension. Iohexol caused little or no change in left ventricular pressure and dimensions. In addition, Renografin-76 caused marked arterial hypotension and large increases in coronary and femoral blood flows, while iohexol caused no significant change in arterial pressure and coronary blood flow, and a mild increase in femoral blood flow. Based on these findings, it is concluded that iohexol is preferable to standard ionic contrast material for deriving basal physiologic information from computed tomographic and digital vascular studies.
Animals↗
Validation of cardiac output estimates by digital video subtraction angiography in dogs. Correlation with thermodilution values.
To determine the validity of cardiac output estimates obtained by digital video subtraction angiography (DVSA), they were compared with thermodilution values in 6 anesthetized dogs. Multiple levels of cardiac output were produced in each dog by graded openings of peripheral arteriovenous fistulas. Both direct contrast and mask-mode images were evaluated. There was good correlation between thermodilution and direct contrast values (r = 0.88) as well as between thermodilution and mask-mode values (r = 0.89), though the mask-mode outputs were 12 +/- 1.1% less than the direct contrast values (p less than 0.05). Direct contrast and mask-mode values correlated well (n = 6; r greater than or equal to 0.95). Digital outputs exhibited little variation, indicating excellent reproducibility. These results demonstrate the validity of area-length estimates of cardiac output by DVSA.
Angiocardiography↗
A noncomputerized count-based technique for the determination of resting left ventricular ejection fraction.
A noncomputerized, count-based technique for the determination of left ventricular ejection fraction (LVEF), which does not use geometric assumptions of left ventricular shape, was developed. The noncomputerized technique and computerized multigated ventriculography using both fixed and variable region-of-interest (ROI) methods were performed on 16 patients. The LVEFs obtained with the noncomputerized technique correlated well with both the fixed ROI computerized technique (r = .87) and the variable ROI computerized technique (r = .86). It is concluded that when a computer is not available, the noncomputerized technique is a valid alternative for the determination of LVEF in resting patients in stable sinus rhythm.
Cardiac Output↗
Quantitation of left ventricular dimensions and function by digital video subtraction angiography.
Digital video subtraction angiography (DVSA) after central intravenous administration of contrast media was used in experimental animals and in patients with suspected coronary artery disease to quantitate left ventricular dimensions and regional and global contractile function. In animals, measurements of left ventricular (LV) volumes, wall thickness, ejection fraction, segmental contraction, and cardiac output correlated closely with sonocardiometry or thermodilution measurements. In patients, volumes and ejection fractions calculated from mask mode digital images correlated closely with direct left ventriculography. Global and segmental contractile function was displayed in patients by ejection shell images, stroke volume images, and time interval difference images. Central cardiovascular function was also quantitated by measurement of pulmonary transit time and calculation of pulmonary blood volume from digital fluoroscopic images. DVSA was shown to be useful and accurate in the quantitation of central cardiovascular physiology.
Angiocardiography↗
Right and left ventricular dysfunction in patients with chronic obstructive lung disease. Assessment by first-pass radionuclide angiography.
To evaluate the relationship between right and left ventricular function in patients with obstructive lund disease, we studied 10 normal subjects (group 1) and 37 patients with chronic obstructive pulmonary disease by first pass radionuclide angiography. These 37 patients were divided into three groups: nine with mild chronic obstructive pulmonary disease (group 2), 20 with severe chronic obstructive pulmonary disease (group 3) and eight with severe chronic obstructive pulmonary disease and primary left ventricular disease (group 4). In each subject right ventricular ejection fraction (RVEF), left ventricular ejection fraction (LVEF) and ejection fraction during first third of systole (first third LVEF) were calculated. (For table: see text.) p less than 0.05 versus 1. All subjects in group 2 had normal left ventricular and right ventricular function. In group 3, 11 of 10 (55 per cent) had a low RVEF and three of 20 (15 per cent) a low LVEF. However eight of 20 in this group (40 per cent) had a depressed first-third LVEF. The correlation between decline in RVEF and first-third LVEF was good r = 0.73. We conclude that (1) certain indices of early systolic left ventricular ejection are abnormal in many patients with chronic obstructive pulmonary disease and correlate with the decline in right ventricular function; (2) this is not seen in patients with mild chronic obstructive pulmonary disease and is worse in patients with underlying left-sided heart disease.
Adult↗
Profiles of radionuclide left ventricular ejection fraction changes induced by supine bicycle exercise in normals and patients with coronary heart disease.
This paper presents the profiles of left ventricular ejection fraction (EF) during and following supine bicycle exercise in normal subjects and in patients with coronary heart disease, as well as the relationship of the described patterns to clinical parameters. Twenty normal men and 40 patients with coronary artery disease were studied using gated equilibrium radionuclide angiography (EQ-EF). In the normals, during exercise, EF increased by a mean of 25% of the resting value, with an increase of no less than 11%. The exercise-limiting symptom in patients with coronary artery disease was angina pectoris in 20 and fatique in the other 20 patients. In the angina patients, there was a mean decrease in EF of 20%, and in the other coronary artery disease patients ejection fraction change little. Only two patients with coronary artery disease increased from a normal resting value to peak exercise by more than 11%, and they had isolated right coronary lesions. An "overshoot" elevation of ejection fraction above resting levels was demonstrated following termination of exercise in most patients. The patients with a significant fall in exercise ejection fraction more frequently had abnormal exercise-induced ECG changes as well as abnormal left ventriculograms and more severe coronary artery disease at cardiac catheterization than the patients with little change in ejection fraction. We conclude that 1) normals could be separated from most patients with significant coronary artery disease in this study population; 2) ejection fraction must be measured at maximal exercise for it to have diagnostic value, since there could be normal rise before and after peak exercise and an abnormal response missed; and 3) the ejection fraction response to exercise reflects the severity of the underlying coronary artery disease. The described patterns of exercise-induced changes in left ventricular ejection fraction are important to consider when using this new technique to diagnose and evaluate patients with coronary artery disease.
Adult↗
A comparison of peak-to-peak pulmonary transit time determined by digital intravenous angiography with standard dye-dilution techniques in anesthetized dogs.
To evaluate the relationship between mean pulmonary transit time and peak-to-peak transit time by digital intravenous angiography six dogs were assessed during either isoproterenol or phenylephrine infusion. Acutely anesthetized dogs were instrumented with catheters in the pulmonary artery, left atrium, and carotid artery. An injection catheter was placed in the inferior vena cava, and contrast injections were made with a power injector (30 cc/second for 1 second of Renografin 76). Peak-to-peak transit times (pulmonary artery-left atrial time) were derived from videodensitometric time-absorption curves. Mean transit time was calculated from the usual optical densitometric analyses of green dye injected first in the pulmonary artery and then in the left atrium (sampled in a carotid artery). Peak-to-peak times averaged 3.6% greater than mean transit time (4.39 +/- 1.76 seconds vs. 4.24 +/- 1.82 seconds, P less than .05), though they correlated well with green dye values (r = .97; y = .97 x +.44). It was concluded that peak-to-peak transit times are excellent approximates of standard dye-dilution mean transit times and may simplify calculations of the pulmonary circulation when videodensitometric or radionuclide techniques are utilized.
Anesthesia↗
The effect of ischemia and isoproterenol on the pulmonary circulation in dogs. Analysis by digital intravenous angiography.
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Angiography↗
Intravascular and extravascular pulmonary fluid volumes II. Response to rapid increases in left atrial pressure and the theoretical implications for pulmonary radiographic and radionuclide imaging.
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Animals↗
Phenylephrine stress in the evaluation of patients with congestive cardiomyopathies.
To analyze the effects of acute elevations in arterial blood pressure on pulmonary blood volume (PBV) and left ventricular function, 21 outpatients with congestive cardiomyopathies and stable condition and eight normal control subjects were studied using equilibrium radionuclide angiography during the infusion of phenylephrine. The myopathy patients were subdivided into seven patients who developed rales during phenylephrine infusion and 14 who did not. All of the myopathy subjects had reduced ejection fractions and enlarged end-diastolic volumes at rest. With phenylephrine, the patients who developed rales (Group 1) and those who did not (Group 2) had similar changes in left ventricular parameters (ie, ejection fraction declined and end-diastolic volume increased). With phenylephrine, however, the patients with rales had marked increases in radionuclide estimates of PBV (48.2 +/- 1.2 to 71.2 +/- 4.1 units, P less than .01, a mean increase of 48%), while in the subjects without rales, PBV increased from 48 +/- 11 to 54.6 +/- 2.2 (P less than .05, a mean increase of only 14%). Normal individuals (Group 3) had a qualitatively similar response to phenylephrine as did the myopathy patients (a decline in ejection fraction and an increase in end-diastolic volume), with no significant change in PBV. Noninvasive phenylephrine radionuclide imaging may help characterize patients with varying forms of congestive cardiomyopathies, direct appropriate therapy, and help explain the pathophysiology of clinical findings.
Adult↗
Digital intravenous ventriculography. Comparison of volumes from mask-mode and nonsubtracted images with thermodilution and sonocardiometric measurements.
Left ventricular volumes calculated from mask-mode (MM) images obtained by digital intravenous ventriculography (DIV) were compared with volumes determined from direct contrast images (CV), thermodilution and sonomicrometer measurements in six anesthetized dogs in which volumes were varied by isoproterenol and phenylephrine infusions. Short and long axis sonomicrometer crystals allowed continuous measurement of cardiac size and function. The MM and CV ejection fractions and volumes correlated well with each other (r greater than or equal to 0.96) through the MM volumes consistently underestimated the CV volumes by 12 +/- 3%. Analyzing each dog individually, both CV and MM volumes and ejection fractions correlated well with sonomicrometer results. In addition CV and MM estimates of stroke volume correlated well (r greater than or equal to 0.91) with the thermodilution values, although the CV values exceeded the thermodilution value by 17 +/- 4%. We conclude that MM analysis of left ventricular function correlates well with standard measures of cardiac dimensional changes and agrees with, though underestimates, the simultaneous nonsubtracted contrast ventriculographic images.
Animals↗
Effect of patient imaging angle on apparent cardiac volumes and the potential impact on measurement of valvular regurgitant fractions.
The accurate measurement of cardiac chamber volume is of major importance in assessing cardiac performance. Accurate equilibrium radionuclide volume estimations are difficult to obtain, due to the geometry of the chambers, and the physical characteristics of the imaging system. The purpose of this study was to examine the effects of imaging projections on relative cardiac chamber volumes, indexes, and stroke volume ratios. Twenty-two male patients, free of clinical evidence of disease, were studied. A series of four 2-minute acquisitions were made with the patient successively imaged in the anterior, 30 degrees left anterior oblique (LAO), 45 degrees LAO, and 60 degrees LAO projections with 15 degrees of caudal inclination. Filtered stroke volume and original images were used by the operator to assign right ventricular (RV), left ventricular (LV), and a combined right and left ventricular (TOT) regions-of-interest. From the data we determined end-diastolic counts (EDC), end-systolic counts (ESC), stroke counts (SC), ejection fractions (EF), and R/L stroke count ratios. The following changes were observed as the projection was moved from the anterior to 60 degrees LAO: 1) all RV parameters decreased in value, including, RVEDC (P less than .001), RVESC (P less than .01), RVESC (P less than .01) and RVEF (P less than .001); 2) LVEDC and LVESC (both P less than .01) increased while LVEF decreased (P less than .004); and 3) the R/L stroke count ratio decreased (P less than .001). Variability could be explained by 1) chamber overlap and geometry; 2) patient variability; and 3) intrachamber, interchamber and chest wall photon attenuation and scatter. We suggest that close attention to detail, with computer assistance, to optimally position the patient may reduce the effect of inherent limitations in radionuclide volumetric measurements, thus improving the reliability and usefulness of existing studies.
Aged↗
A comparison of the effects of intravenous and direct left ventricular contrast injections on left ventricular function.
Digital intravenous ventriculography (DIV) has become increasingly recognized as a useful and reliable approach for evaluating left ventricular (LV) performance. While it might be assumed that the hemodynamic changes caused by intravenous injection of contrast media are less than those caused by direct LV injection, these responses have not actually been compared. Accordingly, the hemodynamic effects of IV and direct LV contrast injections were compared in eight anesthetized dogs instrumented with two pairs of ultrasonic dimension crystals, one to measure LV endocardial segment length and one to measure LV internal dimension, and a LV high-fidelity pressure catheter. The alterations in LV dimension and pressure were similar using both injection techniques, though they were less marked with IV injection. Both routes of injection caused a significant decline in LV pressure (P less than 0.05) which was greatest at 30 seconds after injection, and a significant (P less than 0.05) increase in end-diastolic dimension (which was greatest between 10-30 seconds) and extent of change in LV diameter (P less than 0.01). The afterload reducing effects of the contrast media increased the rate of LV segment length shortening slightly after LV injection but not with IV injection. These data demonstrate no important differences in the hemodynamic response to IV and LV injection of contrast media. The induced hemodynamic changes after IV administration were relatively small in magnitude and transient in duration and probably not sufficient to obviate quantitative analysis of LV dimensions and function by digital intravenous angiography.
Animals↗
Perfluoroctylbromide. Acute hemodynamic effects, in pigs, of intravenous administration compared with the standard ionic contrast media.
Perfluoroctylbromide (PFOB) is a relatively new noniodinated contrast media that, after intravenous administration, produces prolonged opacification of the blood pool and subsequently selectively enhances the liver and spleen on computed tomography. There has been concern regarding the hemodynamic effect of this agent but little actual knowledge exists in this regard. Accordingly, the acute transient hemodynamic effects of PFOB emulsion were evaluated in five pigs and compared with the standard ionic contrast agent meglumine sodium diatrizoate (Renografin-76). Left ventricular (LV) pressure, internal diameter, and wall thickness were monitored during the alternate intravenous administration of 930 mg/ml PFOB and 370 mg/ml R-76 at a rate of 20 mls/second for a total volume of 1 ml/kg body weight. Renografin-76 caused a significant decrease in LV pressure and dp/dt (rate of change of LV pressure), and an increase in LV end-systolic diameter and a decrease in LV end-diastolic wall thickness. PFOB caused no change in LV pressure and dimensions. Thus, rapid intravenous administration of PFOB does not induce significant acute alterations in left ventricular pressure, dp/dt, dimension, or wall thickness.
Animals↗
The effect of pulmonic and aortic constriction on regional left ventricular thickening dynamics, geometry and the radius of septal curvature. Analysis by gated computed transmission tomography.
We evaluated the effects of aortic and pulmonic constriction on cross-sectional cardiac dynamics using prospectively gated computed transmission tomography (CT) in six dogs in order to evaluate 1) the effect of altering the end-diastolic trans-septal pressure gradient on the radius of septal curvature, and 2) the effect of right ventricular overload on regional left ventricular geometry and wall thickening dynamics. Cross-sectional CT data were obtained in a control state, at two incrementally higher levels of right ventricular end-diastolic pressure produced by constriction of the pulmonary artery (PA1 and PA2) and then at one higher level of left ventricular end-diastolic pressure resulting from acute aortic constriction (Ao). Using fluid-filled polyethylene catheters, we measured right and left ventricular pressures simultaneous with the image acquisition. The measured radius of septal curvature was then normalized by the calculated average radius derived from the left ventricular area at end-diastole. The end-diastolic radius of septal curvature ratio increased as delta [LVEDP-RVEDP] declined (from 1.03 +/- 0.13 at control; 1.20 +/- 0.18 PA2; 1.27 +/- 0.14 PA2 and 0.87 +/- 0.11 Ao). As this LVEDP-RVEDP gradient declined (ie, RVEDP increased in proportion to LVEDP) septal wall thickening declined (P less than 0.005), with significantly less change in left ventricular anterior or lateral wall thickening. With PA hypertension, LV end-diastolic volume and percent delta volume significantly declined (P less than 0.005) while RV end-diastolic volume increased. With PA pressure overload, septum-free wall distance declined (P less than 0.01) as did percent shortening along this dimension (P less than 0.01). We conclude that predictable changes in LV and RV dynamics occur when trans-septal pressure gradients change.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Thallium pulmonary scintigraphy. Relationship to pulmonary fluid volumes during left atrial hypertension and the acute release of pressure.
To evaluate the relationship between thallium-201 lung activity and pulmonary fluid volumes, we compared thallium pulmonary scintigrams with measures of intravascular (PBV), extravascular (EVLW) and total lung water (TLW) during gradual left atrial (LA) hypertension and then serially after the acute release of pressure. The study group was composed of nine mongrel dogs who were each studied at seven levels of elevated LA pressure, and then every 15 minutes for 2 hours after the acute release of pressure. During LA pressure (congestion phase) elevation, lung counts (normalized for myocardial activity), correlated best with TLW (r = .91), rather than PBV (r = .84) or EVLW (r = .81). After the release of pressure (recovery phase), lung counts correlated well with EVLW (r = .92) and TLW (r = .82), but not with PBV (r = .28). Postmortem lung counts from 197 separate lung sections correlated well with the corresponding wet weight/dry weight ratio from that section (r = .81). Thus, we conclude that changes in pulmonary thallium emissions during cardiogenic pulmonary edema relate to corresponding changes in pulmonary fluid volumes. During congestion, the confounding effects of nonlinear increases in EVLW and PBV make thallium emissions more a marker of TLW than either the intravascular or extravascular pulmonary fluid compartment. After pressure release, PBV immediately returns to normal, at which time EVLW and pulmonary emissions correlate closely. These latter data, more applicable to postexercise stress thallium data, lend support to the hypothesis that elevated pulmonary emissions during postexercise thallium scintigrams reflect elevations in EVLW that develop during exercise.
Animals↗