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

Acute effects of chemoradiation on cardiac function in oesophageal cancer: a MUGA scan and echo-based study

OBJECTIVE

To study the acute effects of concurrent chemoradiation on global and regional cardiac contractility and correlate with radiation dose.

METHODS

16 patients of locally advanced oesophageal squamous cell carcinoma were serially followed up with multiple-gated acquisition (MUGA) scans and echocardiograms during the course of concurrent chemoradiation to evaluate the ejection fractions (EFs) and pericardial status, respectively. Changes in cardiac contractility were correlated with the doses received by the heart.

RESULTS

Concurrent chemoradiation resulted in a significant reduction in the contractility of both left ventricle (LV) and right ventricle (RV), with a mean reduction of LVEF by 5.6% and RVEF by 6.5% over the course of treatment, which had a significant correlation with the radiation doses received by the ventricles (p=0.001). On further analysis, correlation between radiation dose and decrease in contractility was more significant in the boost phase (16 Gy in 8 fractions over one and a half weeks; p=0.001 for LV and p=0.008 for RV) compared with the initial phase (40 Gy in 20 fractions over 4 weeks; p=0.184 for LV and p=0.269 for RV). One out of 16 patients developed mild acute pericarditis.

CONCLUSIONS

Concurrent chemoradiation resulted in acute decrease in EF of both ventricles in a dose-dependent manner. Correlation between cardiac doses and decrease in EF was more marked in the boost phase, suggesting a possible threshold of 40 Gy for this impairment. Nevertheless, conclusions regarding this possible threshold need to be interpreted with caution given the small sample size.

Left ventricular volumes with ventricular inhibited and atrial triggered ventricular pacing

Left ventricular (LV) volumes were assessed with equilibrium radionuclide angiocardiography at rest and during exercise in nine patients with high-degree AV block treated with ventricular inhibited (VVI), which was subsequently changed to atrial triggered ventricular pacing (VAT). The ventricular rates were similar at rest but higher on exercise during treatment with VAT (102 ppm) than with VVI (71 bpm). The LV end-diastolic volume tended to be larger with VAT than with VVI pacing, both at rest (185 vs. 145 ml) and during exercise (220 vs. 162 ml). The LV end-systolic volume also tended to be larger at rest (110 vs. 81 ml) and during exercise (149 vs. 83 ml). The LV ejection fractions were similar at rest but on exercise they decreased to significantly lower levels with VAT (0.35), while remaining unchanged with VVI (0.47). One mechanism for this difference could be an enhanced contractile state in VVI pacing compared with VAT pacing.

Automatic quantification of left ventricular ejection fraction from gated blood pool SPECT

BACKGROUND

Cardiac gated blood pool single photon emission computed tomography (GBPS) better separates cardiac chambers compared with planar radionuclide ventriculography (PRNV). We have developed a completely automatic algorithm to measure quantitatively the left ventricular ejection fraction (LVEF) from gated technetium 99m-red blood cells (RBC) GBPS short-axis 3-dimensional image volumes.

METHODS AND RESULTS

The algorithm determines an ellipsoidal coordinate system for the left ventricle and then computes a static estimate of the endocardial surface by use of counts and count gradients. A dynamic surface representing the endocardium is computed for each interval of the cardiac cycle by use of additional information from the temporal Fourier transform of the image data sets. The algorithm then calculates the left ventricular volume for each interval and computes LVEF from the end-diastolic and end-systolic volumes. The algorithm was developed in a pilot group (N = 45) and validated in a second group (N = 89) of patients who underwent PRNV and 8-interval GBPS. Technically inadequate studies (N = 38) were rejected before grouping and processing. Automatic identification and contouring of the left ventricle was successful in 121/172 patients (70%) globally and in 76/89 patients (85 %) in the validation group. Correlation between LVEFs measured from GBPS and PRNV was high (y = 2.00 + 1.01x, r = 0.89), with GBPS LVEF significantly higher than PRNV LVEF (average difference = 2.8%, P < .004).

CONCLUSIONS

Our automatic algorithm agrees with conventional radionuclide measurements of LVEF and provides the basis for 3-dimensional analysis of wall motion.

Effects of carvedilol on systolic and diastolic left ventricular performance in idiopathic dilated cardiomyopathy or ischemic cardiomyopathy

Recent evidence has shown that improvement in left ventricular (LV) systolic function in patients with New York Heart Association class II to III heart failure occurs with beta-adrenergic blocking agents. However the specific effects on LV diastolic function have been subjected to only limited examination. This study investigated the effects of the combined beta blocker/vasodilator, carvedilol, on systolic and diastolic LV performance in dilated cardiomyopathy. Thirty-six patients with New York Heart Association II to III heart failure and LV ejection fraction < or = 0.35 were entered into either arm of this placebo-controlled, double-blind 4-month trial. Twenty-one subjects were entered into the carvedilol treatment arm and 15 patients were entered into the placebo arm in a 3:2 ratio. Carvedilol therapy resulted in a significant improvement in LV ejection fraction, from 0.22 +/- 0.02 to 0.30 +/- 0.02 when compared with the placebo group (0.19 +/- 0.02 to 0.21 +/- 0.02 at baseline and after 4 months of therapy, respectively; p = 0.0001). However, no significant change in radionuclide parameters of LV diastolic function, including peak filling rate or time to peak filling rate, was observed. LV end-diastolic volume index did not change with carvedilol therapy, whereas end-diastolic volume index increased in the placebo group, although the difference between groups at 4 months was significant (p = 0.02). In conjunction with these changes, end-systolic volume index was smaller at 4 months after carvedilol treatment compared with that of the placebo group (p = 0.04). Thus, these results demonstrate that in moderate chronic heart failure, systolic LV performance improves but diastolic LV function does not improve when compared with placebo after treatment with carvedilol.

Accuracy of biplane long-axis left ventricular volume determined by cine magnetic resonance imaging in patients with regional and global dysfunction

Left ventricular (LV) volumes and ejection fraction can be obtained by applying Simpson's rule to multiple short-axis tomographic planes. A simpler method for determining LV volumes using the area-length equation is widely accepted and requires less time to acquire and analyze. Its accuracy, however, is questionable in deformed or asymmetrically contracting ventricles. This study compares biplane long-axis to serial short-axis computed LV volumes obtained by cine gradient-echo magnetic resonance imaging (MRI) in 2 distinct patient populations: (1) patients with global LV dysfunction, and (2) patients with regional LV dysfunction. A total of 114 patients were studied using both methods. Among 37 patients with global LV dysfunction, there was no statistically significant difference between methods (long axis vs short axis) for determining LV end-diastolic volume (203 +/- 91 vs 201 +/- 90 ml), end-systolic volume (142 +/- 81 vs 141 +/- 82 ml), and ejection fraction (33 +/- 12 vs 33 +/- 13%). However, in the 77 patients with regional dysfunction, LV end-diastolic volume was statistically slightly higher when obtained using the long-axis approach (157 +/- 53 vs 152 +/- 51 ml; p=0.004). Otherwise, end-systolic volume (97 +/- 49 vs 95 +/- 49 ml) and ejection fraction (40 +/- 13 vs 40 +/- 13%) were similar (p=NS). The correlation between LV volumes and ejection fractions for both groups was excellent (r >0.91). Thus, in this study group, biplane long-axis and serial short-axis computed LV volumes and ejection fractions were similar in patients with global or regional LV dysfunction. In critically ill patients unable to complete a comprehensive MRI examination, the biplane long-axis-derived volumes provide adequate data.

Automated determination of left ventricular volume curves from bi-plane digital angiography without explicit use of edge detection algorithms

Automated computation of left ventricular (LV) global and regional function using contrast angiography has not yet become a routine procedure with the advent of digital cardiac imaging systems. We describe a new technique to compute LV volume curves which does not require the use of manual or semi-automated detection of endocardial borders and provides on-line implementation of volumetric curves and computation of pressure volume loops during catheterization. The approach uses the concepts of variable entropy (or information) of left ventricular images throughout the cardiac cycle. LV volume curves are computed with an interpolation scheme using those LV volume curves of a patient data base which are associated with the closest variation in entropy in the RAO projection to the analyzed patient data according to a simple metric. Computed LV volume curves were correlated with those obtained with manual tracing. Left ventricular ejection fraction (LVEF), time to end systole (TES) and angiographic cardiac output (CO) were compared to those obtained with the manual method. Results using a data base of 365 patients revealed excellent correlation (r = 0.97) between manually derived volume curves and volume curves computed with the automated technique within a large range of LVEFs. In 87% of all cases the computed LVEF values were found within +/- 10% of the value obtained with the gold standard method. The systolic phase of the volume curves showed that 81% of all cases had the same accuracy. The TES showed much more variation due to undersampling of the cardiac cycle in time (r = 0.71).

Computation of left ventricular volume curves from gated blood pool studies without explicit use of edge detection algorithms: concise communication

A new technique has been developed to compute left ventricular (LV) time activity curves from gated blood pool (GBP) studies without the use of manual, semiautomated or fully automated edge detection algorithms. The method utilizes the correlation of entropy calculated from the counts of a fixed region of interest covering the left ventricle during a cardiac cycle to compute the LV volume curve for a new patient. The new LV volume curve is obtained through interpolation of those volume curves of a data base which are associated with the closest variations in normalized entropy to the new one. The computed LV time activity curves agree with those obtained from manual or fully automated outlines of the left ventricle within 9 percent for the selected set of 67 patients demonstrating the potential of the method. The accuracy of calculated LV volume curves can be improved theoretically to any degree by increasing the number of cases in the data base of known statistical feature vectors associated with the LV images and LV volume curves. The new method for computation of LV curves is very efficient and robust when compared to traditional techniques.

Endothelin in human congestive heart failure

BACKGROUND

Although recent investigations report the elevation of plasma endothelin (ET) in congestive heart failure (CHF), it remains unclear if this elevation is that of the biologically active peptide ET-1 or of its precursor big-ET. Furthermore, it is unclear if such elevation is associated with increased myocardial ET and if the molecular form from cardiac tissue is altered ET. Last, it remains to be established whether circulating ET is increased at the earliest stage of CHF in patients with asymptomatic left ventricular dysfunction and correlates with the magnitude of ventricular dysfunction.

METHODS AND RESULTS

The present study was designed to investigate concentrations and molecular forms of ET in plasma and cardiac tissue in healthy subjects and CHF patients with New York Heart Association (NYHA) class I through IV using cardiac radionuclide angiogram, cardiac myocardial biopsy, radioimmunoassay, gel permeation chromatography (GPC), and immunohistochemical staining (IHCS). Plasma ET was increased only in patients with moderate (NYHA class III) or severe (NYHA class IV) CHF compared with healthy subjects and individuals with asymptomatic (NYHA class I) or mild (NYHA class II) CHF. The elevation of circulating ET in CHF showed a negative correlation with left ventricular ejection fraction and cardiac index and a positive correlation with functional class and left ventricular end-diastolic volume index. GPC demonstrated that immunoreactive plasma ET was ET-1 in healthy subjects and both mature ET-1 and its precursor big-ET in severe CHF patients, with big-ET the predominant molecular form. Cardiac tissue concentrations and IHCS revealed ET presence in healthy atrial and ventricular tissue, which were not different in severe CHF. GPC revealed that the molecular form of cardiac ET was ET-1 in both healthy and CHF hearts.

CONCLUSIONS

The present study establishes for the first time that the elevation of plasma ET in severe human CHF represents principally elevation of big-ET. Second, ET is present in healthy and failing myocardia, and its activity by both immunohistochemistry and radioimmunoassay is not changed in CHF. Furthermore, the elevated plasma ET is characteristic of severe CHF and not asymptomatic or mild CHF. In addition, the degree of plasma elevation of ET correlates with the magnitude of alterations in cardiac hemodynamics and functional class. The present study confirms and extends previous investigations of ET in human CHF and establishes the evolution of circulating and local cardiac ET in the spectrum of human CHF.

Global and regional parameters of left ventricular performance in healthy subjects during rest and exercise assessed by radionuclide ventriculography

The aim of our study was to analyze numerous global and regional parameters of left ventricular (LV) performance during rest and exercise, in the group of 14 healthy subjects, by quantitative gated equilibrium ventriculography in left anterior oblique view (45 degrees). The global LV parameters at rest vs. exercise in our study were: heart rate 68.9 +/- 18.4 vs. 137.5 +/- 38.6; systolic blood pressure (mmHg) 121.8 +/- 18.2 vs. 178.6 +/- 31.2; diastolic blood pressure (mmHg) 82.1 +/- 10.8 vs. 90.7 +/- 12.4; double product 8,368.6 +/- 2,308.8 vs. 24,589.3 +/- 8,357.8; global ejection fraction (%) 61.9 +/- 15.4 vs. 72.8 +/- 12.8, end-diastolic volume index (ml/m2) 82.5 +/- 23.2 vs. 96.9 +/- 27.8; end-systolic volume index (ml/m2) 31.8 +/- 19.8 vs. 26.9 +/- 15.4; stroke volume index (ml/m2) 50.6 +/- 17.6 vs. 70.0 +/- 22.6; peak emptying rate (EDV/s) 3.4 +/- 2.6 vs. 8.3 +/- 3.8 and peak filling rate (EDV/s) 3.6 +/- 2.6 vs. 9.6 +/- 3.8. A significant difference (p < 0.05) between rest and exercise was found for all parameters. The highest values of LV regional ejection fraction were found in anterolateral and posterolateral region, while the lowest values were observed in inferoseptal and inferior regions. During exercise a significant increase of regional ejection fraction was found in all regions. The highest percent of radius shortening during rest was in anterolateral and posterolateral regions, and lowest in inferoseptal and inferior regions. The same sequence was found during exercise, and the difference in percent of radius shortening, between rest and exercise was significant in all regions. The observed normal values of global and regional parameters of LV function during rest may serve as a contribution for referent values. Our results on regional ejection fraction and the percent of radius shortening in rest, and their change during exercise, offer the possibility of additional information in the investigation of cardiac patients by means of radionuclide ventriculography.

The effect of venous occlusion with tourniquets on peripheral blood pooling and ventricular function

Rotating tourniquets were once part of the traditional treatment of acute pulmonary edema. Their effectiveness has been questioned and vasodilator therapy has replaced them, but early favorable results suggested that they may play a beneficial role. A radioisotope technique was used to evaluate blood volume increments in the leg after venous occlusion at 60 mm Hg in 26 patients with left ventricular dysfunction following myocardial infarction. Mean radionuclide counts (reflecting the blood volume distal to the occlusion) increased from the preocclusion value. Thus, satisfactory trapping of blood is achieved. However, mean left ventricular ejection fraction (EF) decreased slightly but significantly and this decrease in EF was observed in 18 of 26 patients. Left ventricular end-diastolic and end-systolic volume equivalents tended to decrease slightly but not in all patients. Mean stroke volume and cardiac output equivalents were reduced by 14 percent while peripheral resistance increased significantly. The present study thus fails to support the hypothesis that preload reduction by tourniquets improves left ventricular function; the exact opposite effect may occur because of increased afterload.

Dissociation of end systole from end ejection in patients with long-term mitral regurgitation

To determine whether left ventricular (LV) end systole and end ejection uncouple in patients with long-term mitral regurgitation, 59 patients (22 control patients with atypical chest pain, 21 patients with aortic regurgitation, and 16 patients with mitral regurgitation) were studied with micromanometer LV catheters and radionuclide angiograms. End systole was defined as the time of occurrence (Tmax) of the maximum time-varying elastance (Emax), and end ejection was defined as the time of occurrence of minimum ventricular volume (minV) and zero systolic flow as approximated by the aortic dicrotic notch (Aodi). The temporal relation between end systole and end ejection in the control patients was Tmax (331 +/- 42 [SD] msec), minV (336 +/- 36 msec), and then, zero systolic flow (355 +/- 23 msec). This temporal relation was maintained in the patients with aortic regurgitation. In contrast, in the patients with mitral regurgitation, the temporal relation was Tmax (266 +/- 49 msec), zero systolic flow (310 +/- 37 msec, p less than 0.01 vs. Tmax), and then, minV (355 +/- 37 msec, p less than 0.001 vs. Tmax and p less than 0.01 vs. Aodi). Additionally, the average Tmax occurred earlier in the patients with mitral regurgitation than in the control patients and patients with aortic regurgitation (p less than 0.01, for both), whereas the average time to minimum ventricular volume was similar in all three patient groups. Moreover, the average time to zero systolic flow also occurred earlier in the patients with mitral regurgitation than in the control patients (p less than 0.01) and patients with aortic regurgitation (p less than 0.05). Because of the dissociation of end systole from minimum ventricular volume in the patients with mitral regurgitation, the end-ejection pressure-volume relations calculated at minimum ventricular volume did not correlate (r = -0.09), whereas those calculated at zero systolic flow did correlate (r = 0.88) with the Emax slope values. We conclude that end ejection, defined as minimum ventricular volume, dissociates from end systole in patients with mitral regurgitation because of the shortened time to LV end systole in association with preservation of the time to LV end ejection due to the low impedance to ejection presented by the left atrium. Therefore, pressure-volume relations calculated at minimum ventricular volume might not be useful for assessing LV chamber performance in some patients with mitral regurgitation.

First passage radionuclide cardiography for determination of cardiac output: evaluation of an improved method

A noninvasive method for determination of cardiac output by aid of first passage radionuclide cardiography is presented. As opposed to most other scintigraphic methods, a forward blood flow is measured, even in patients with valvar incompetence. In addition, the technique allows measurement of cardiac output in the presence of cardiac arrhythmias. No geometrical assumptions, corrections for radiation attenuation, loss of tracer, or empirical correction factors due to extracardiac radioactivity are required. We have evaluated the method in 19 patients with various heart diseases by comparison of the radionuclide cardiac outputs with those derived from the thermodilution technique performed simultaneously. Eight patients had valvar incompetence and 2 had cardiac arrhythmias. The mean radionuclide and thermodilution cardiac output values were 5.03 l/min (SD 1.21) and 5.18 l/min (SD 1.09), respectively. The 95% confidence interval for the bias was -0.40 to 0.10 l/min, and correlation analysis demonstrated an excellent correlation between results obtained with the two methods, r = 0.91 (P less than 0.001). This study shows that the improved gamma camera method represents a valid noninvasive technique for determination of cardiac output.

Long-term stepwise sustained improvement in left ventricular ejection fraction after myocardial infarction

Radionuclide left ventricular ejection fraction, end-diastolic volume, and exercise capacity were determined in 34 selected patients who survived a first Q wave anterior infarction. Patients were included in the study if they had no subsequent cardiac events (unstable angina or myocardial infarction) during the average follow-up period of 47 months (range = 36 to 70 months); none was treated with thrombolysis, coronary angioplasty, or bypass grafting. Overall, mean left ventricular ejection fraction increased from 28 +/- 10% 1 month after infarction to 33 +/- 10% at 3 years (p less than 0.01); mean end-diastolic volume decreased from 217 +/- 99 ml to 171 +/- 80 ml (p less than 0.002). Stepwise improvement in left ventricular ejection fraction occurred in 15 of these patients (group B) and was associated with a significant increase in exercise capacity. Mean ejection fraction in group B was 26 +/- 7% at 1 month and 41 +/- 10% at 3 years (p less than 0.001). In all of these patients there was improved regional wall motion in the noninfarct zone, whereas five patients also showed improvement in the infarct zone. The results indicate a progressive improvement in left ventricular function that occurs over time in some patients after first Q wave anterior infarction, independent of intervention.

First myocardial infarction: age and ejection fraction identify a low-risk group

This study examines patients with a first myocardial infarction (MI) (about 70% of the population, n = 2089), and identifies factors associated with 1-year cardiac mortality in patients discharged alive. With the use of multivarate analysis of variables observed at hospital discharge in patients with a first MI, age was the most important predictor, followed by left ventricular ejection fraction (LVEF) (determined in 56%) and other variables. Based on this finding, age subsets (less than or equal to 50, 51 to 70, greater than 70 years) were related to LVEF groups (less than or equal to 0.40, 0.41 to 0.50, greater than 0.50). Patients with a first MI who were less than 50 years of age with LVEF greater than 0.40 and patients between 51 and 70 years of age with LVEF greater than 0.50 had a very low risk for 1-year cardiac death, 1.2 +/- 1.1% (95% confidence interval). Such patients comprised 47% of individuals with a first MI having an LVEF determination. Mortality in the remaining patients less than 70 years was 7.4 +/- 3.5%. Mortality for patients greater than 70 years was high, 22.2 +/- 6.6%. Thus with LVEF as the only predischarge test, a sizable low risk group can be identified among patients with a first MI.

Factors influencing the variations of ejection fraction during exercise in chronic aortic regurgitation

The influence of left ventricular volume variations and regurgitant fraction variations upon left ventricular ejection fraction during exercise was examined using equilibrium radionuclide angiography in patients suffering from aortic regurgitation. Ejection fraction (EF), regurgitant fraction (RF), end diastolic volume (EDV) and end systolic volume (ESV) variations from rest to peak exercise were determined in 44 patients suffering from chronic aortic regurgitation (AR) and in 8 healthy volunteers (C). In C, EF increased (+0.10 +/- 0.03, P less than 0.01) and ESV decreased significantly (-23% +/- 12%, P less than 0.01), RF and EDV did not vary significantly. In AR patients, EF, EDV and ESV did not vary significantly because of important scattering of individual values. Changes in EF and ESV were inversely correlated (r = -0.79, P less than 0.01) and RF decreased significantly (-0.12 +/- 0.10, P less than 0.01). Volumes and EF changes during exercise occurred in three different ways. In a 1st subgroup of 7 patients, EF increased (+0.09 +/- 0.03, P less than 0.05) in conjunction with a reduction of ESV (-24% +/- 12%, P less than 0.05) without a significant change in EDV. In a 2nd group of 22 patients, EF decreased (-0.04 +/- 0.07, P less than 0.01) in association with an increase in ESV (+17% +/- 16%, P less than 0.01) and no change in EDV. In a 2nd group of 22 patients, EF decreased (-0.04 +/- 0.07, P less than 0.01) in association with an increase in ESV (+17% +/- 16%, P less than 0.01) and no change in EDV. In a 3rd subgroup of 15 patients, EF decreased (-0.02 +/- 0.06, P less than 0.01) despite a reduction in ESV (-7% +/- 6%, P less than 0.01) because of a dramatic EDV decrease (-10% +/- 6%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac dynamics during supine exercise in cyclosporine-treated orthotopic heart transplant recipients: assessment by radionuclide angiography

The mechanisms by which the denervated heart responds to supine exercise were assessed by equilibrium gated radionuclide angiography in 18 cardiac transplant recipients 1 to 25 months (mean 11) after surgery. Results were compared with those in 15 normal subjects. Exercise duration among transplant recipients did not differ significantly from that in normal subjects. The heart rate at rest in transplant patients was 30% higher than in normal volunteers. Heart rate increased only 3% between rest and the first stage of exercise in transplant recipients compared with a 37% increase in the normal group (p less than 0.001). Cardiac output at rest was similar in both groups although the rate of rise of cardiac output and peak cardiac output were significantly lower among the transplant recipients. In early exercise, the means by which cardiac output increased in the transplant patients differed significantly from normal. In the transplant recipients, the left ventricular end-diastolic volume index increased 14% compared with a decrease of 2% in normal subjects (p less than 0.001) during the first stage of exercise. At the same time, the end-systolic volume index increased 6% in the transplant group but decreased 11% in normal subjects (p less than 0.001). These changes resulted in an overall increase in stroke volume by 20% in the transplant group compared with only a slight increase (+3%) in normal subjects (p less than 0.001) during the first stage of exercise. Among transplant recipients, the stroke volume index plateaued after the first stage of exercise, which, in combination with the blunted chronotropic response, resulted in a peak cardiac index 25% lower than that in normal subjects (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Radionuclide ventriculography and hemodynamic evaluation by right heart catheterization with exercise for assessing the functional significance of coronary artery stenoses. A comparative study

A series of 13 patients with significant coronary stenoses but without prior myocardial infarction were simultaneously studied by right heart catheterization and radionuclide ventriculography to determine the extent to which abnormal responses in left ventricular ejection fraction and wall motion to maximum exercise are paralleled by abnormal left ventricular filling pressures. The correlations of the filling pressure as evaluated by the diastolic pulmonary artery pressure with both the exercise ejection fraction and the rest-to-exercise change in ejection fraction were high (r = -0.89, P less than 0.01 and r = -0.76, P less than 0.01, respectively). In addition, the filling-pressure response to stress separated the patients into distinct radionuclide categories. All the 7 patients with grossly abnormal filling pressures (P greater than or equal to 30 mmHg) developed regional wall motion abnormalities with exercise as evaluated by visual interpretation or quantitative phase analysis. These patients also had a decrease in ejection fraction from rest to exercise ranging from -9% to -32% together with an exercise ejection fraction below 50%. Conversely, these abnormalities were never found in patients with filling pressures below this threshold level. The data suggest that radionuclide ventriculography and measurement of left ventricular filling pressure with exercise yield corresponding results when assessing the functional significance of coronary stenoses in normotensive patients without prior myocardial infarction and normal global left ventricular function at rest.

Exercise response of the systolic pressure to end-systolic volume ratio in patients with coronary artery disease

The exercise response of the ratio of systolic blood pressure to end-systolic volume was studied in 243 patients with chest pain and coronary artery disease who underwent supine rest and exercise equilibrium radionuclide angiography. There was a wide variation in both rest and exercise variables in this group. The exercise response of the systolic pressure/volume ratio also varied greatly, ranging from a decrease of 59% to an increase of 136%. Twenty-one clinical, catheterization and radionuclide angiographic variables were examined to determine their relation to the exercise response of the systolic pressure/volume ratio; nine variables were individually correlated with this ratio. Multiple regression analysis identified the change in end-diastolic volume index with exercise, rest systolic blood pressure, coronary artery Gensini score and peak work load as significant independent predictors of the exercise response of the systolic pressure/volume ratio; the latter correlated significantly with the change in ejection fraction with exercise (r = 0.73, p less than 0.0001). Its sensitivity for the detection of coronary artery disease in the study group (84%) and its "normalcy rate" in a group of 120 patients with a low likelihood of coronary artery disease (81%) were similar to those of the peak exercise ejection fraction (75 and 82%, respectively). These results demonstrate that the exercise response of the systolic pressure/end-systolic volume ratio is a complex response that is influenced by several pathophysiologic variables in the presence of coronary artery disease. It does not offer any advantage over ejection fraction measurements for the detection of exercise-induced ischemia.

Reproducibility of rest and exercise left ventricular ejection fraction and volumes in chronic aortic regurgitation

To assess the variability of rest and exercise radionuclide ventriculography in patients with aortic regurgitation (AR), 22 patients in stable condition with chronic AR underwent radionuclide ventriculography at rest and during exercise for measurement of left ventricular volumes and ejection fraction (EF) on 2 occasions 3 months apart. For the group, there were no significant differences between the findings of the 2 studies except for a slightly lower exercise end-systolic volume on the second study. The inter-study differences and variabilities (expressed as the standard deviation of differences) for rest and exercise EF and change in EF were 0 +/- 0.04, +0.02 +/- 0.05 and +0.01 +/- 0.05, respectively. Thus, although mean differences were minor, considerable individual variability occurred, the magnitude of which was similar to that reported for other patient populations. In 3 patients who had an initial normal response to exercise (increase in EF greater than or equal to 0.05), the response became abnormal and in 2 who initially had an abnormal response, the response normalized. This variability must be considered in clinical decision-making or in research study design for patients with chronic AR.

Infarct artery perfusion and changes in left ventricular volume in the month after acute myocardial infarction

The relation between perfusion of the infarct-related artery and changes in left ventricular volume and function during the month after a first myocardial infarction was examined in 40 patients who did not receive thrombolytic therapy. Infarct artery perfusion was documented at predischarge coronary angiography, and left ventricular volume was measured by nongeometric analysis of radionuclide angiograms performed within 48 hours of infarction and at 1 month. Left ventricular dilation (greater than or equal to 20% increase in volume) developed in 16 patients, whereas 5 patients had a decrease in left ventricular volume of greater than or equal to 20% by 1 month. Left ventricular dilation occurred in all 14 patients without perfusion of the infarct-related artery, compared with only 2 of 26 patients with perfusion of this artery due to subtotal occlusion or collateral vessels. All five patients whose left ventricular volume decreased by greater than or equal to 20% had a perfused infarct artery. Multiple linear regression analysis confirmed that the degree of perfusion of the infarct artery (partial r = 0.58, p = 0.001) was a more important predictor of volume change than was infarct size measured by peak creatine kinase (partial r = 0.30, p = 0.009) or QRS score (partial r = 0.20, p = 0.087). Left ventricular ejection fraction decreased from 0.38 +/- 0.10 to 0.30 +/- 0.16 (p = 0.05) in 11 patients with an anterior infarct and ventricular dilation; it increased from 0.45 +/- 0.10 to 0.62 +/- 0.07 (p = 0.02) in the 5 patients with a greater than or equal to 20% decrease in volume.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of age and gender on left ventricular response to supine exercise in asymptomatic normal subjects

The performance of normal subjects during radionuclide ventriculography has been related to age, but the combined effects of age and sex on exercise ventricular function are not well described. We studied 55 normal volunteers, 27 men (age = 30 +/- 10 years) and 28 women (age = 33 +/- 14 years), free of chest pain syndromes, during supine rest/exercise radionuclide ventriculography performed to fatigue. Resting left ventricular ejection fraction did not differ between male and female subjects (64 +/- 5.4 vs 64 +/- 6.1; p = NS). Both the peak left ventricular ejection fraction (78 +/- 4.4 vs 72 +/- 9.2; p less than 0.001) and the change in ejection fraction with exercise (14 +/- 4.0 vs 7.9 +/- 7.0; p less than 0.001) were significantly greater in men compared to respective values in women. Regression analysis showed that sex (r = 0.51; p less than 0.001) but not age (r = -0.18; p = 0.19) was a significant predictor of change in ejection fraction with exercise. Data on left ventricular volume response to exercise, available in 43 subjects, revealed that men had a greater percentage of decline in end-systolic volume with exercise than women (-47 +/- 15 vs -24 +/- 26; p less than 0.001). It is concluded that sex exerts a significant influence on normal left ventricular response to fatigue-limited supine exercise and that the gender difference is mediated, in part, by left ventricular end-systolic volume response to exercise.

Position as a variable for cardiovascular responses during exercise

Twenty-one normal young male subjects underwent resting and exercise (bicycle) radionuclide angiography in the full supine and 70 degrees upright tilt positions in order to examine the effects of position on left ventricular size and performance, hemodynamics, and exercise duration. All subjects also underwent full (90 degrees) upright bicycle ergometry with respiratory gas analysis to establish the level of maximal exercise capacity for each. Body position significantly (p less than 0.05) affected resting and exercise cardiovascular parameters. End-diastolic and endsystolic left ventricular volumes and stroke volume were larger in the supine position, both at rest and during exercise. The cardiac output at rest and during exercise were comparable for the two positions; an increase in resting and exercise heart rate in the 70 degrees tilt position compensated for the reduced stroke volume of this posture. At maximal exercise, the 70 degrees upright position was associated with a greater response in left ventricular ejection fraction, otherwise this parameter was not position related. Exercise capacity, in terms of duration and workload, was significantly higher in the supine (1870 +/- 390 s) and full upright (1830 +/- 250 s) positions than in the 70 degrees tilt position (1730 +/- 260 s). Changes in body position significantly alter parameters of ventricular, cardiovascular, and exercise performance.

Immediate effect of expiratory loading on left ventricular stroke volume

While the steady-state effects of positive pleural pressure on the circulation have been extensively studied, less is known about the immediate effects of positive intrathoracic pressure on cardiac dynamics. Therefore, we performed electrocardiographically gated radionuclide ventriculography with a respiratory gating technique in nine healthy subjects during quiet breathing and during expiration against a 24 cm H2O expiratory threshold load. During expiration, respiratory loading caused an increase in stroke counts by 29.4% (p less than .001) due to an increase in end-diastolic counts of 26.1% (p less than .001). End-systolic counts also rose 18.8% (p less than .05). The ejection fraction did not change significantly. These findings indicate that the increase in left ventricular stroke volume that occurs during the first 1 or 2 beats of a loaded expiration is due to an increase in left ventricular filling and not to augmentation of left ventricular ejection. This immediate increase in pulmonary venous return may reflect increased distensibility of the left ventricle due to decreased filling of the right ventricle.

Infarct size--can it be measured or modified in humans?

Despite more than 15 years of intensive experimental and clinical research in the general area of limiting infarct size, no treatment has been shown to be so efficacious and relatively free of side effects that its routine use can be recommended. In addition, there is no ideal means of measuring infarct size as yet. However, considerable progress has been made in understanding mechanisms responsible for irreversible cellular injury and in identifying factors and anatomic alterations responsible for or contributing to the development of transmural (Q wave) and non-transmural (non-Q wave) myocardial infarcts. Interventions are available that are capable of causing rapid coronary thrombolysis, and techniques are becoming available tht have increasing power to size myocardial infarcts and estimate both segmental and ventricular function. Experimental studies have also suggested a potential benefit from a combination of reperfusion therapy with selected pharmacologic intervention in reducing infarct size and preserving ventricular function. It seems likely that this general area will remain an intensive area of clinical research in the immediate future.

Comparison of contrast x-ray biplane cineangiography and technetium-99m radionuclide scans for measurement of ventricular volumes in human autopsy hearts

The area-length method is widely used in the determination of left ventricular volume. Although previous studies have reported that this technique overestimates true volume (TV), it is unknown whether this overestimation is the same at different volumes. In the present study, with the use of 10 postmortem human hearts, left ventricular volumes were determined by contrast x-ray biplane cine ventriculography (LVA), biplane radionuclide (LVR), and absolute-counts (LVC) technetium scans, and the results were correlated with TV. LVA correlated well with TV (r = 0.98). LVR correlated well with TV (r = 0.97), and LVR also correlated well with LVA (r = 0.96). Both area-length techniques (LVA and LVR) resulted in overestimation of TV with an upward shift of the regression line of 30.4ml +/- 3.8 (SEM) for LVA and 28.5 +/- 4.4 for LVR. The percentage of overestimation error was significantly greater at smaller left ventricular volumes (error = 33% at TV = 30ml and 10% at TV = 100ml, p less than 0.001). LVC correlated well with TV (r = 0.99), TVA, and LVR but underestimated TV. Thus left ventricular volumes can be reliably obtained from LVR and LVA by means of the area-length method and from LVC. When the area-length method is utilized, the percentage of error in the determination of left ventricular volume is proportional to 1/TV.

Limitations and advantages of the ejection fraction for defining high risk after acute myocardial infarction

Left ventricular (LV) ejection fraction (EF) is known to be related to prognosis after acute myocardial infarction (AMI), but its role alone and in combination with other factors in the definition of a high-risk group has not been adequately specified. Several recent multicenter studies emphasize that LVEF together with features of ventricular ectopic activity during ambulatory electrocardiography define a group at high risk for death for up to 3 years. However, these high-risk groups comprised only a small fraction of the population (less than 7.5%) and failed to include 75% or more (less than 25% specificity) of observed events. In our study, LVEF was determined close to the time of hospital discharge in 750 patients with AMI enrolled in a collaborative study. Used alone, an LVEF of less than 0.45 best defined a high-risk group (39% of the population) yielding 62% sensitivity and 64% specificity for total cardiac mortality by 1 year; it was 77% sensitive for sudden death alone. In a multivariate analysis together with other factors, LVEF was an independent predictor, but other markers of LV dysfunction entered before LVEF with similar sensitivity for total cardiac deaths, but with increased specificity (75%). When an LVEF of less than 0.45 was used together with the presence of complex arrhythmias to define a high-risk group (19% of the population), sensitivity decreased to 39% and specificity increased to 84%. Thus, LVEF is a simple and effective alternative to multivariate analysis for risk assessment after AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of a background correction that considers the heart volume on radionuclide left ventricular ejection fraction determination

A correction of background activity that considers the heart volume is introduced in radionuclide equilibrium cardiography. Left ventricular ejection fraction (LVEF) was determined in 19 patients with ischaemic heart disease by multigated equilibrium scan with 99Tcm-labelled red blood cells (99Tcm-RBC). Assuming that the majority of background activity in the ventricular and periventricular regions of interest arises from 99Tcm-RBC in lung tissue, a ventricular/periventricular background ratio was calculated from the distribution of 99Tcm-labelled macroaggregated albumin. The mean relative distribution of pulmonary 99Tcm-RBC activity in the ventricular region of interest was 0.590 (range 0.279-1.061) compared with the periventricular region. The modified background correction resulted in a mean LVEF of 43.0% (range 12.9-67.6%) compared with 46.8% (range 10.9-67.8%) with the standard correction, p less than 0.005. Since no attempt was made to calculate the proportion of 99Tcm-RBC activity arising from the myocardium and thoracic wall, this difference represents an upper limit of the general overestimation of LVEF obtained by the standard calculation. A further decrease in LVEF was seen when no background correction was applied. The present results suggest that standard LVEF calculation, by neglecting the background volume displaced by the cardiac blood pool, results in a slight overestimation of LVEF.

Determination of left ventricular ejection fraction using ultrafast computed tomography

We evaluated ultrafast CT as a method to measure left ventricular ejection fraction in 16 adults with congenital or acquired heart disease who underwent cardiac catheterization. CT scanning of the left ventricle was performed at 4 to 12 adjacent 1 cm levels (depending on heart size) at 50 msec/scan for one cardiac cycle, with the table positioned with an axial tilt of 10 to 20 degrees and a lateral slew of 5 to 10 degrees to best approximate the long axis of the left ventricle. Image enhancement was achieved by an injection of 25 ml of Renografin-76 via a peripheral vein, with scanning timed to coincide with maximal enhancement of the left ventricular cavity. Ejection fraction was computed by measuring the percent change in area of the left ventricle from diastole (largest area) to systole (smallest area) in a single slice at the mid-left ventricular level. Mean ejection fraction for the group was 58.1 +/- 15.1% (range 24% to 84%). The ejection fraction from left ventriculography, computed from biplane images using the Dodge (area-length) formula, was 59.6 +/- 12.3% (range 28% to 77%). There was an excellent correlation between left ventricular ejection fraction by CT and ventriculography (r = 0.91, y = 1.1x - 8.5, p less than 0.001). This study demonstrates that ultrafast CT can provide an accurate measure of left ventricular ejection fraction by simple methodology.

Radionuclide left ventricular function curve during atrial pacing in normal subjects and in patients with coronary artery disease

We used radionuclide angiography during right atrial pacing to assess left ventricular function in 7 normal subjects and 20 patients with coronary artery disease. A left ventricular function curve relating stroke volume to end-diastolic volume was plotted for each patient. The normal pacing ventricular function curve was a straight line passing through the origin of axes. The pacing ventricular function curve was abnormal in 18 of the 20 patients with coronary artery disease, and three different shaped curves were obtained, reflecting decreased contractile force for the same end-diastolic volume during ischemia. Cardiac output and blood pressure do not change during atrial pacing, thus the Frank-Starling relationship is evaluated by this method during almost experimentally controlled conditions. Relating stroke volume to end-diastolic volume, and not end-diastolic pressure, distinguishes between overall left ventricular systolic function and left ventricular compliance.

Radionuclide determination of absolute LV volumes: interstudy, interobserver and intraobserver variances

The results of 22 absolute left ventricular volume (LVV) determinations by a radionuclide (RN) method are compared to the results obtained by contrast ventriculography (CV). Another 10 patients were analysed in order to evaluate the interstudy, interobserver and intraobserver variances. Good correlation was shown between the RN and CV measurements of the end diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV) and ejection fraction (EF), but the RN method overestimates the EDV and ESV. The EF was underestimated, but no difference could be shown for the SV. On the inter- and intraobserver levels, regression analysis yielded excellent correlation (r greater than 0.99 in all cases) with no statistically significant difference (P less than 0.05). The interstudy variance was minimal as indicated by regression analysis (r greater than 0.87) and no statistically significant difference (P less than 0.05) could be shown between studies. The results indicate that the RN method of LVV determination can be used in intervention studies over a limited period.

Effects of buccal nitrate on left ventricular haemodynamics and volume at rest and during exercise-induced angina

A novel approach has been employed to characterize the effects of a cardioactive drug on left ventricular haemodynamics and volume by simultaneously determining cardiac stroke volume (thermodilution) and left ventricular ejection fraction (nuclear probe). The effects of glyceryl trinitrate were evaluated in 12 patients with angiographically proven coronary artery disease at rest and 3, 7, 15 and 30 min following 10 mg buccal nitroglycerin (Suscard) administration. The impact of the drug on left ventricular haemodynamics and volume during exercise-induced angina was determined by repeating exercise 30 min following drug administration, at the workload that reliably induced angina during control exercise. At rest buccal nitroglycerin reduced systemic arterial pressure, cardiac and stroke volume indices, and increased heart rate. The left ventricular ejection fraction (E.F.) increased; its filling pressure together with end-diastolic and end-systolic volumes were significantly reduced. Compared with control supine-bicycle exercise, the drug reduced mean systemic arterial pressure and left ventricular filling pressure without change in cardiac and stroke volume indices. There was a smaller increase in left ventricular volume during exercise, and the fall in E.F. was attenuated. These data demonstrated differential actions of glyceryl trinitrate on left ventricular function related to the physiological state in obstructive coronary artery disease. These techniques appear to hold promise in the evaluation of the effects of other therapies on left ventricular volume in coronary artery disease.

The reproducibility of nongeometric analysis of cardiac output and left ventricular volume by radionuclide angiography

This study examines the reproducibility of individual radionuclide attenuation factors used in the calculation of cardiac output and left ventricular volume by the nongeometric radionuclide method. Twenty male patients were studied at rest with thermodilution measurements of cardiac output on two separate days. Simultaneous equilibrium radionuclide angiograms were performed and left ventricular stroke volume and cardiac output were determined by the nongeometric method. Individual patient attenuation factors were calculated as the ratio of thermodilution and radionuclide cardiac output measurements at each study. There was a close linear relationship between radionuclide and thermodilution measurements of cardiac output in each study (r = 0.88 study 1, r = 0.97 study 2). A similar relationship was found for measurements of left ventricular stroke volume (r = 0.86, study 1, r = 0.97 study 2). Individual radionuclide attenuation factors ranged from 2.49 to 3.46 in study 1 and from 2.77 to 3.29 in study 2. The individual attenuation factors were reproducible to within 10% in 13 patients and to within 15% in 19 patients. When cardiac output was calculated from the radionuclide data of study 2, by means of individual attenuation factors previously determined in study 1, there was a good correlation with the simultaneous thermodilution measurements of cardiac output (r = 0.92, SEE = 0.38 L/min). Individual radionuclide attenuation factors show little variation in serial studies. Thus the nongeometric radionuclide technique can be used to make accurate serial measurements of cardiac output and left ventricular volume.

Maintenance of exercise stroke volume during ventricular versus atrial synchronous pacing: role of contractility

Although atrial synchronous and rate-responsive ventricular pacing have been compared, the importance of maintaining synchronized atrial systole in addition to rate responsiveness has been incompletely defined. That is, the effects of these two pacing modes on cardiac volumes and contractility have not been studied. Accordingly, 16 patients with normal ventricular function were studied while in the upright position and at rest with gated radionuclide ventriculography during both atrial synchronous and ventricular pacing. Twelve of these patients were also studied during low-level upright exercise (300 kilopond-meters). Rest and exercise ventricular pacing heart rates were matched to those recorded with synchronous pacing. Ventricular volumes were determined with a counts-based method. The ejection fraction and peak systolic pressure/end-systolic volumes or contractility between the two pacing modes. However, during exercise to identical heart rates, blood pressures, and workloads, although stroke volume was the same during exercise with atrial synchronous and ventricular pacing (78 +/- 13 vs 75 +/- 12 ml), end-diastolic and end-systolic volumes were lower with ventricular pacing than with atrial synchronous pacing (end-diastolic volume 101 +/- 13 vs 113 +/- 16 ml, p less than .001; end-systolic volume 26 +/- 4 vs 35 +/- 7 ml, p less than .001). Stroke volume during ventricular paced exercise was maintained at atrial synchronous pacing levels by means of increased contractility (ejection fraction of 74 +/- 4% during ventricular pacing vs 69 +/- 5% during atrial synchronous pacing, p = .002; peak systolic pressure/end-systolic volume ratio of 6.51 +/- 1 during ventricular pacing vs 4.85 +/- 1 during atrial synchronous pacing, p less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of left ventricular volume using single-photon emission computed tomography

A count-based method for measuring left ventricular (LV) volume using technetium-99m-labeled red cells and ungated single-photon emission computed tomography is described. The tomographic slices were used to determine the counts per milliliter in the center of the left ventricle and total LV counts, which were used to derive mean LV volume. End-diastolic and end-systolic volumes were calculated from the mean volume using the LV time-activity curve from planar gated blood pool images. Phantom evaluation with simulated LV volumes (50 to 400 ml) in air, in a phantom filled with water, with 10% background, and with a simulated right ventricle, showed excellent accuracy. For clinical validation, 30 patients underwent electrocardiographically gated planar and nongated tomographic acquisition of the cardiac blood pool followed by single-plane cineangiography. For end-diastolic and end-systolic volumes combined, the correlation with cineangiography showed a standard error of the estimate (SEE) of 24 ml and 14 ml, respectively. Mean intra- and interobserver deviation was 12 ml and 14 ml (SEE 13 ml and 16 ml), respectively. It is concluded that this noninvasive count-based technique, requiring no assumptions regarding LV geometry, is an accurate and reproducible way to measure LV volume.

Spatial R wave amplitude changes during exercise: relation with left ventricular ischemia and function

Thirty patients who exhibited increased and 65 patients decreased spatial R wave amplitude during exercise testing were compared for left ventricular function and ischemic variables. Spatial R wave amplitude was derived from the three-dimensional Frank X, Y, Z leads using computerized methods. All patients had stable coronary artery disease and they were classified into two groups: one that attained a higher (n = 48) and one a lower (n = 47) median value of maximal heart rate during exercise (161 beats/min). Within these two groups, patients with increasing or decreasing spatial R wave amplitude during exercise were analyzed for differences in oxygen consumption, exercise-induced changes in spatial R wave amplitude, ST segment depression laterally (ST60, lead X), ST displacement spatially, left ventricular ejection fraction at rest, change in left ventricular ejection fraction with exercise and thallium-201 ischemia during exercise. Significant differences were demonstrated only in exercise-induced spatial R wave amplitude changes (p less than 0.0001). There was no significant correlation between exercise-induced change in heart rate and change in spatial R wave amplitude in either the group with increasing or the group with decreasing spatial R wave amplitude. It is concluded that changes in spatial R wave amplitude during exercise are not related to ischemic electrocardiographic or thallium-201 imaging changes or to left ventricular ejection fraction determined at rest or during exercise.

Measurement of left-ventricular volumes using an internal standard

When performing equilibrium radionuclide angiocardiography with two successive acquisition views, absolute left-ventricular volumes can be calculated using an 'internal standard' generated by a computer in the left-ventricular cavity. The method is based on the computed ratio of maximum to global activity in the 40 degree-left-anterior-oblique view after background correction and on the measured depth of the left ventricle in almost-orthogonal, 30 degree-left-posterior-oblique Fourier first-harmonic images. The method does not require blood sampling or correction for self attenuation. The intra- and interobserver reproducibility is excellent, even in patients with severe impairment of the ventricular-contractility pattern. When compared with a classical method requiring venous-blood counting and an attenuation correction factor, the accuracy of the internal-standard method was fairly good, with a regression coefficient of 0.90.

Left ventricular diastolic filling in patients with coronary artery disease and normal left ventricular function

Abnormal left ventricular diastolic filling (DF) has been noted in coronary disease (CD) patients with normal left ventricular function (NLVF). Inclusion of patients with regional wall disease, hypertension, and left ventricular hypertrophy may be responsible for abnormal DF. We evaluated left ventricular DF curves derived from gated blood pool scans in 21 normals (group 1), in 38 CD patients with NLVF specifically defined (group 2), and in 28 CD patients with ejection fractions greater than 50% and regional disease (group 3). The peak filling rate (PFR), mean filling rate (MFR), the percentage of stroke volume filled at one third of diastole (%SV-1/3 DT) and at the end of the rapid filling period (%SV-RFP) were determined. Groups 1 and 2 had similar DF parameters. Group 2 patients with 75% obstructive left anterior descending disease (LAD) had a reduced %SV-RFP and PFR (2.56 +/- 0.56 end-diastolic volumes/sec [EDV/S]) as compared to normals (3.11 +/- 0.65 EDV/S, p less than 0.01). Group 3 patients had a reduced PFR (2.14 +/- 0.53 EDV/S, p less than 0.001), MFR, %SV-1/3 DT, and %SV-RFP. DF in CD patients with NLVF was similar to normals in a select group of patients but was abnormal in patients with regional disease and greater than 75% LAD disease with NLVF.

Left ventricular diastolic filling in patients with left ventricular dysfunction

The pattern of abnormal left ventricular diastolic filling and its specificity in coronary disease patients with severe left ventricular dysfunction has received little attention. We evaluated the left ventricular diastolic filling curve derived from gated blood pool scans in 21 normals, 61 coronary disease patients with ejection fractions less than or equal to 30%, and 51 congestive cardiomyopathy patients with ejection fraction less than or equal to 30%. The peak filling rate (PFR), peak ejection rate (PER), PFR/PER and the % stroke volume filled at 1/3 of diastole (%SV-1/3 DT) and at the end of the rapid filling period (%SV-RFP) were determined for each group. The PFR and PER were reduced in both coronary disease and congestive cardiomyopathy groups. The PFR/PER was increased in the coronary disease group (1.19 +/- 0.28) and congestive cardiomyopathy group (1.21 +/- 0.32) as compared to normals (0.93 +/- 0.20, P less than 0.001). A greater %SV-1/3 DT and %SV-RFP were noted in both coronary disease and congestive cardiomyopathy groups. Coronary disease and congestive cardiomyopathy patients with a mean pulmonary capillary pressure (PCP) greater than or equal to 18 mm Hg had a greater PFR/PER, %SV-1/3 DT, and %SV-RFP than patients with a PCP less than 18 mm Hg. An abnormal and nonspecific pattern of left ventricular diastolic filling is present in both coronary disease and congestive cardiomyopathy patients and is characterized by an increased PFR/PER, a greater %SV-1/3 DT, and a greater %SV-RFP. This pattern may be related to elevated PCPs.

Validation of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volume: comparison with cast-validated biplane cineventriculography

To determine the accuracy of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volumes, we initially studied 14 postmortem human right ventricular casts by water displacement and biplane cineventriculography. Biplane cineventriculographic right ventricular cast volumes, calculated by a modification of Simpson's rule algorithm, correlated well with right ventricular cast volumes measured by water displacement (r = .97, y = 8 + 0.88x, SEE = 6 ml). Moreover, the mean volumes obtained by both methods were no different (73 +/- 28 vs 73 +/- 25 ml). Subsequently, we studied 16 patients by both biplane cineventriculography and equilibrium radionuclide angiography. The uncorrected radionuclide right ventricular volumes were calculated by normalizing background corrected end-diastolic and end-systolic counts from hand-drawn regions of interest obtained by phase analysis for cardiac cycles processed, frame rate, and blood sample counts. Attenuation correction was performed by a simple geometric method. The attenuation-corrected radionuclide right ventricular end-diastolic volumes correlated with the cineventriculographic end-diastolic volumes (r = .91, y = 3 + 0.92x, SEE = 27 ml). Similarly, the attenuation-corrected radionuclide right ventricular end-systolic volumes correlated with the cineventriculographic end-systolic volumes (r = .93, y = - 1 + 0.91x, SEE = 16 ml). Also, the mean attenuation-corrected radionuclide end-diastolic and end-systolic volumes were no different than the average cineventriculographic end-diastolic and end-systolic volumes (160 +/- 61 and 83 +/- 44 vs 170 +/- 61 and 86 +/- 43 ml, respectively). Comparison of the uncorrected and attenuation-corrected radionuclide right ventricular volumes demonstrated narrower 95% confidence intervals for the attentuation-corrected right ventricular volume determinations over a wide range of cineventriculographic volumes. Thus we conclude that: (1) attenuation-corrected radionuclide right ventricular end-diastolic and end-systolic volumes compare closely with those obtained by a cast-validated biplane cineventriculographic method and (2) attenuation-corrected radionuclide right ventricular volumes correspond more closely to determinations of biplane cineventriculographic right ventricular volumes and are thus likely to be more accurate than uncorrected radionuclide right ventricular volumes.

Use of clinical data in predicting improvement in exercise capacity after cardiac rehabilitation

Fifty-nine men with coronary heart disease underwent 1 year of supervised aerobic exercise. They performed exercise tests for maximal oxygen uptake, ST segment analysis, thallium scintigraphy and radionuclide ventriculography before and after the year of exercise. A computerized data base that included clinical descriptors and exercise test results was retrospectively reviewed to determine whether initial features could predict the patient's response to the exercise intervention. Poor correlations were found between the initial measurements and change in maximal oxygen consumption and other indexes of training effect. Patients who initially were in the poorest state of fitness showed the most improvement with training. None of the initial features from the history and physical examination, treadmill study or radionuclide studies was a good predictor of a beneficial result from the exercise program. The usual measurements of work intensity during training were poor predictors of outcome. A significant decrease in the amount of ischemia measured by thallium perfusion scintigraphy was demonstrated after training.

Left ventricular volume determination using single-photon emission computed tomography

A new method for measuring left ventricular (LV) volume based on gated single-photon emission computed tomography (SPECT) is described. Preliminary phantom studies showed an excellent correlation between SPECT and observed volumes (r = 0.99, standard error of the estimate [SEE] = 4.9 ml). SPECT was performed 24 hours after biplane contrast LV angiography in 36 patients. Transaxial blood pool tomograms were reconstructed by filtered back projection and reoriented to views orthogonal to the cardiac axes. Volume was calculated from serial short-axis tomograms by determining the base, apex and lateral borders of the LV blood pool, ascertaining the number of pixels in this volume and multiplying by the known volume of a pixel. Gated SPECT volumes were compared with contrast angiographic volumes. At end-systole, r = 0.96 and SEE = 12 ml; at end-diastole, r = 0.81 and SEE = 27 ml. For ejection fraction, r = 0.85 and SEE = 0.06. To test interobserver variation in processing, count data from 5 patients were processed twice (r = 0.98, SEE = 8.3 ml). There is an excellent correlation between SPECT and contrast angiographic volumes at end-systole; at end-diastole the relation is good. SPECT requires no arbitrary background correction, allows systematic isolation of the left ventricle from other overlapping cardiac chambers and requires no geometric assumptions for volume determination. It has promise as a direct method for measuring LV volume in a minimally invasive manner.

Count-based scintigraphic method to calculate ventricular volumes in children: in vitro and clinical validation

A "phantom" was used to validate 1) estimates of different depths of a constant radioactivity source, and 2) the calculation of different volumes using a constant depth and different attenuation coefficients. Using data from this in vitro study, scintigraphic estimates of right ventricular volume and ejection fraction were compared with those obtained by cineangiography in 36 children with either a normal right ventricle or various right ventricular diseases. The static program accurately estimates the distance from the radiation source to the collimator surface (r = 0.99). Radionuclide count methods best predict "phantom" volumes using attenuation coefficients between 0.11(-1) and 0.13(-1) cm. A coefficient of 0.10(-1) underestimates, whereas 0.15(-1) cm grossly overestimates actual volumes. In vivo data were therefore analyzed using an attenuation coefficient of 0.11(-1) with right ventricular counts corrected using either right ventricular or left ventricular background. Closest agreement between scintigraphic and cineangiographic volumes was obtained using right ventricular background, although end-diastolic volumes larger than 100 ml were substantially underestimated. On the basis of this study, the use of two different attenuation coefficients is suggested: the smaller 0.11(-1) cm to calculate end-systolic and end-diastolic volumes and the larger 0.15(-1) cm for volumes greater than 100 ml.

Combined first-pass and equilibrium radionuclide ventriculography and comparison with left ventricular/right ventricular stroke count ratio in mitral and aortic regurgitation

Effective and total left ventricular (LV) stroke volume were assessed in 31 patients with verified aortic or mitral regurgitation, or both, and in 22 patients with normal valvular function using combined first-pass and equilibrium radionuclide ventriculography. The difference between these 2 volumes as a fraction of LV stroke volume was taken as the radionuclide regurgitant fraction. The results were compared with the LV/right ventricular (RV) stroke count ratio and with the angiographic regurgitant fraction according to the method of Sandler and Dodge. Radionuclide regurgitant fraction derived from 2 determinations with a time interval of 1 week showed good reproducibility (n = 15, r = 0.96, SEE = 9.1). Sensitivity was 100% for radionuclide regurgitant fraction and 87% for LV/RV stroke count ratio at equal specificity (100%). Radionuclide regurgitant fraction was more sensitive, especially in severely ill patients, in whom additional RV volume overload led to false-low or false-negative ratios. Angiographic and radionuclide regurgitant fraction showed linear correlation (r = 0.79, p less than 0.001). In contrast, because 5 patients had RV volume overload, only a weak correlation could be noticed between angiography and LV/RV stroke count ratio (r = 0.47, p less than 0.05). Excluding these patients, correlation substantially improved (r = 0.74, p less than 0.001). The combination of first-pass and equilibrium radionuclide ventriculography is a sensitive, specific and well reproducible method for the evaluation of mitral and aortic regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in exercise capacity and associated changes in hemodynamics and left ventricular function after the addition of metoprolol to nifedipine in patients with stable exertional angina

In 10 men with stable exertional angina, the changes in exercise capacity, hemodynamics, and left ventricular (LV) function were measured after 20 mg sublingual nifedipine (N) and again after adding 100 mg oral metoprolol (M). Nifedipine alone did not significantly improve exercise workloads (+18%) and duration (+21%), but the addition of metoprolol increased both parameters by a further 37 and 32%, respectively (both p less than 0.005 vs. N). After nifedipine the onset of angina was slightly delayed (5.14 +/- 2.41 min placebo (P), 6.00 +/- 2.31 min N, p less than 0.1) and occurred at higher workloads (36 +/- 17 W P, 43 +/- 8 W N, p less than 0.1). After the addition of metoprolol, the onset of angina was delayed substantially more (9.57 +/- 2.22 min, p less than 0.001 vs. P and N) and occurred at much higher workloads (62 +/- 20 W, p less than 0.001 vs. P and N). At rest (R) and during exercise (E), nifedipine decreased systemic vascular resistance (-36% R, -27% E, both p less than 0.001) and mean arterial pressure (-18% R, -21% E, both p less than 0.001), and increased heart rate (+15% R, +11% E, both p less than 0.001), Pulmonary artery wedge pressure on exercise increased less (22 +/- 7 mmHg P, 13 +/- 5 mmHg N, p less than 0.001). After adding metoprolol, the major change was a reduced heart rate (-25% vs. N at R and E, both p less than 0.001), and arterial pressure was unaltered. Pulmonary artery wedge pressure on exercise increased to 18 +/- 5 mmHg (p less than 0.05 vs. N). Exercise LV ejection fraction and volume did not change significantly after adding metoprolol despite marked improvement in angina. In this acute exercise study in patients with stable exertional angina, metoprolol added to nifedipine markedly improved exercise capacity by preventing the increase in heart rate seen with nifedipine. In our patients with relatively normal LV function at rest, the combination was safe and produced no deleterious effects on LV function.