Evaluation of left ventricular function by radionuclide angiography during exercise in normal subjects and in patients with chronic coronary heart disease

Congestive heart failure and ejection fraction in acute myocardial infarction

Left ventricular ejection fraction (EF) was determined by means of radionuclide ventriculography (RNV) in 477 patients 8-12 days after an acute myocardial infarction (AMI). EF was correlated to infarct size and clinical and radiological parameters of congestive heart failure (CHF). The 138 patients (29%) who had signs of CHF had a mean (+/- SD) EF of 35 +/- 14% and a relative heart volume of 597 +/- 112 ml/m2 compared to 51 +/- 14% and 487 +/- 88 ml/m2 among those without CHF. The 52 patients who also had radiological signs of CHF had a mean EF of 27 +/- 12% versus 35 +/- 14% among those with clinical signs and symptoms of CHF. Presence of CHF was positively correlated to the size of AMI and to the reduction of EF. CHF was seen with increasing frequency from 16% in small to 46% in large first infarctions. Patients with reinfarctions showed the same correlation between these parameters, however, with subsequently more depressed EF values and more frequent presence of CHF due to previous myocardial damage. CHF was seldom (8%) observed in patients with EF greater than 50%. In contrast, 67% of the patients with EF less than 35% had CHF. Thus patients with an EF less than 35% represent a high risk group with regard to development of CHF and should be followed closely. It is suggested that radionuclide measurement of EF adds important clinical information in patients with diagnostic uncertainty of CHF.

Evidence of early impairments in both right and left ventricular inotropic reserves in children with Duchenne's muscular dystrophy

In Duchenne's muscular dystrophy (DMD), cardiac function deteriorates with time and heart failure is one of the major causes of death. The aim of the study was to determine if a decrease in the ventricular inotropic reserves could be an early sign of cardiac dysfunction in these children. Nineteen children with DMD (aged 9 to 18 years, mean age 13.6 +/- 2.4) underwent equilibrium radionuclide angiography at rest and during an inotropic stimulation with low-dose dobutamine perfusion (7.5 to 15 microg. kg(-1). min(-1)). In all patients, this investigation was short (<30 minutes), successful, and uncomplicated. At rest, left ventricular (LV) ejection fraction (EF) was normal (>0.50) in 79% of patients, and right ventricular (RV) EF was normal (>0.45) in 95%. There was a trend toward a decrease with age for rest LVEF (p = 0.051) but not for rest RVEF (p = 0.8). By contrast, marked declines with age could be documented for the increases (Delta) in LVEF and RVEF during dobutamine perfusion (p = 0.002 for DeltaLVEF and p = 0.015 for DeltaRVEF). Thus, by multivariate analysis, the sole best indicator of decline in cardiac function with age was LVEF determined with dobutamine. In children with DMD, low-dose dobutamine radionuclide angiography gives evidence of an early decline with age of the inotropic reserves of both ventricles.

Effect of exercise on left and right ventricular ejection fraction and wall motion

OBJECTIVE

We evaluated the diagnostic value of response of left and right ventricular ejection fraction and wall motion to exercise using electron beam computed tomography.

METHODS AND RESULTS

We attempted to determine the value of exercise electron beam computed tomography for detecting coronary artery disease, including evaluation of the right ventricular ejection fraction and wall motion abnormalities. A study of 35 patients undergoing electron beam tomography exercise cine studies and coronary artery angiography for the evaluation of chest pain was performed. Of the 18 patients with significant coronary disease (> or = 50% luminal diameter stenosis in at least one coronary artery), 17 (94%) had failure to increase global left ventricular ejection fraction with exercise. Fourteen of 18 (78%) developed a wall motion abnormality during peak exercise, and eight (44%) developed a regional right ventricular wall motion abnormality during peak exercise. Of the 17 patients without obstructive disease, 14 (82%) had a increase in ejection fraction > or = 5% and none had an abnormal response in left ventricular wall motion during peak exercise (specificity = 100%). The change in right ventricular ejection fraction with exercise was not a significant predictor of obstructive coronary disease in this study (P=NS). Using different criteria during stress to predict coronary disease, the accuracy was 89% (31/35) using an increase of <5% in ejection fraction, 89% (31/35) using the development of a new or worsened wall motion abnormality, and 91% (32/35) using both left ventricular criteria.

CONCLUSION

Our study suggests that exercise electron beam computed tomography appears to be a useful tool for the detection of coronary disease. A increase of <5% in ejection fraction and abnormal left ventricular response to exercise were important predictors, while the exercise induced changes of right ventricular ejection fraction was not a significant predictor of obstructive disease. Both left and right ventricular wall motion abnormalities are useful and important parameters in identifying patients with obstructive disease from those with normal coronary arteries.

Prognostic assessment in coronary artery disease: role of radionuclide angiography

Left ventricular function is one of the most important determinants, if not the most important determinant, of outcome in patients with coronary artery disease. The ability of radionuclide angiography to assess resting and exercise ejection fraction accurately and reproducibly has been shown to be a critical determinant of survival in large-scale studies of survivors of myocardial infarction, as well as patients with chronic stable angina. In addition, several centers have demonstrated that the exercise ejection fraction is an extremely valuable (and perhaps the most valuable) noninvasive parameter in predicting survival among patients with coronary artery disease. The prognostic insights gained from the exercise ejection fraction add incremental predictive information to the coronary anatomic information obtained from coronary arteriography, especially in patients with multivessel disease and those with left ventricular dysfunction at rest.

Effect of enhanced preload with head-out water immersion on exercise response in men with healed myocardial infarction

Head-out water immersion shifts venous blood to the central vasculature and heart and subsequently increases cardiac preload. In healthy men, cardiac output and stroke volume are greater during upright leg cycle exercise in water than on land. Heart rate is similar during work loads < 50% of peak oxygen consumption but is decreased in water at higher work intensities. To determine if men with myocardial infarction (MI) show a similar response, 15 men with a documented MI exercised upright on a leg cycle ergometer on land and immersed in water (31 +/- 1 degree C) to the level of the shoulders. Heart rate, cardiac output (carbon dioxide rebreathing procedure) and oxygen consumption were measured at rest and at work loads corresponding to approximately 40, 60 and 75% of peak oxygen consumption in both environments. At rest, cardiac output and stroke volume were elevated (p < 0.05) in water. During exercise, heart rate, cardiac output and stroke volume did not differ between water and land. When subjects were given beta-blocking medications (n = 8) and subjects with exercise-induced ST-segment depression (n = 5) were separately excluded from the analysis, water immersion still did not significantly change exercise responses. These results suggest that MI alters the normal cardiac response to increased preload during exercise. The alteration may involve reduced myocardial compliance or near-complete use of the Frank-Starling reserve, or both, during land exercise.

Mechanism of exercise-induced hypotension in coronary artery disease

Hypotension during exercise testing has been considered a marker of extensive coronary artery disease (CAD) and poor prognosis. The mechanism of hypotension was examined in 25 CAD patients who developed hypotension during treadmill exercise testing (mean decrease in systolic blood pressure [BP] 33 +/- 13 mm Hg) (group 1) and was compared with the results of 25 CAD patients who had a normal systolic BP response to exercise (mean increase 53 +/- 15 mm Hg) (group 2). The 2 groups were comparable in age, sex, extent of CAD, previous myocardial infarction, left ventricular ejection fraction, history of hypertension and cardiac medications. Exercise heart rate (121 +/- 23 vs 133 +/- 25 beats/min; p = not significant [NS]) and duration (6 +/- 2 vs 7 +/- 3 minutes; p = NS) were comparable. ST-segment depression occurred in 44% of patients in group 1 and in 52% in group 2 (p = NS), and angina during exercise occurred in 60% of both groups. Single-photon emission computed tomographic thallium images were abnormal in 24 patients (96%) in group 1 and in 20 patients (80%) in group 2 (p = NS). Percent thallium abnormality was 19 +/- 12% in group 1, and 18 +/- 14% in group 2 (p = NS), and the severity of thallium abnormality was 710 +/- 510 in group 1, and 510 +/- 500 in group 2 (p = NS). Ischemia involving the inferior/posterior segments was seen in 68% of patients in group 1 and in 60% in group 2 (p = NS). Increased lung thallium uptake was seen in 48% of both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantification of left ventricular performance during transient coronary occlusion at various anatomic sites in humans: a study using tantalum-178 and a multiwire gamma camera

To study the functional significance of transient coronary occlusion on systolic and diastolic left ventricular function relative to the anatomic site of occlusion, first-pass radionuclide angiography with a mobile multiwire gamma camera using tantalum-178 (dose activity less than or equal to 84 mCi/elution) was performed in 46 patients undergoing balloon coronary angioplasty. First-pass images were acquired immediately before angioplasty and during the last 30 s of a 60-s balloon inflation in 23 left anterior descending arteries, 18 right coronary arteries, 8 circumflex arteries and 3 diagonal coronary arteries. Occlusion of the left anterior descending artery resulted in significant decreases in left ventricular ejection fraction (54.6 +/- 12.7% to 32.3 +/- 10.6%, p = 0.0001) and peak filling rate (2.48 +/- 0.68 to 1.75 +/- 0.64 end-diastolic volumes/s, p = 0.0001), accompanied by severe abnormalities in regional function and left ventricular dilation. Right coronary artery occlusion caused inferior hypokinesia, but did not significantly change left ventricular ejection fraction (48.5 +/- 12.4% vs. 45.8 +/- 12.5%, p = NS) or peak filling rate (2.05 +/- 0.81 vs. 2.09 +/- 0.81 end-diastolic volumes/s, p = NS). Circumflex artery occlusion resulted in mild wall motion deterioration and a borderline decrease in ejection fraction (54.7 +/- 11.4% to 50.5 +/- 12%, p = 0.057). Diagonal artery occlusion did not cause significant changes in left ventricular ejection fraction or filling rate. The decrease in left ventricular ejection fraction during coronary occlusion was 9 +/- 25% and 27 +/- 22%, respectively, in those arteries with and without collateral supply (p = 0.052). These data provide strong evidence for the critical importance of the left anterior descending artery and the secondary role of the other coronary arteries in maintaining global systolic and diastolic left ventricular function and suggest a protective role of collateral vessels during coronary occlusion.

Left ventricular dilatation and pulmonary thallium uptake after single-photon emission computer tomography using thallium-201 during adenosine-induced coronary hyperemia

This study examined the implications of left ventricular (LV) dilatation and increased pulmonary thallium uptake during adenosine-induced coronary hyperemia. The lung-to-heart thallium ratio in the initial images was significantly higher in patients with coronary artery disease (CAD) than normal subjects; 0.48 +/- 0.16 in 3-vessel disease (n = 16), 0.43 +/- 0.10 in 2-vessel disease (n = 20), 0.43 +/- 0.08 in 1-vessel disease (n = 16) and 0.36 +/- 0.05 in normal subjects (n = 7) (p less than 0.001, 0.09 and 0.06, respectively). There was a significant correlation between the severity and the extent of the perfusion abnormality (determined from the polar maps) and the lung-to-heart thallium ratio (r = 0.51 and 0.52, respectively, p less than 0.0002). There was also a significant correlation between lung thallium washout and lung-to-heart thallium ratio (r = 0.42, p = 0.0009) and peak heart rate (r = -0.49, p less than 0.0001). The LV dilatation was mostly due to an increase in cavity dimension (30% increase) and to a lesser extent (6% increase) due to increase in LV size. (The cavity dimensions were measured from the short-axis slices at the midventricular level in the initial and delayed images). The dilation was seen in patients with CAD but not in the normal subjects. These changes correlated with the extent and severity of the thallium perfusion abnormality. Thus, adenosine-induced coronary hyperemia may cause LV dilation and increased lung thallium uptake on the basis of subendocardial ischemia.

Effect of preload change on resting and exercise cardiac performance in hypertrophic cardiomyopathy

The purpose of this study was to investigate the hemodynamic responses, at rest and on exercise, of patients with hypertrophic cardiomyopathy to changes in circulating volume. After Swan-Ganz and radial arterial cannulation, 13 patients with hypertrophic cardiomyopathy performed maximal exercise tests after diuretic (frusemide 20 mg intravenously) and after fluid loading (0.9% saline at 10 ml/kg body weight intravenously) on different days. At rest, right atrial and pulmonary capillary wedge pressures increased with volume loading and decreased with a diuretic. There were no significant changes in the resting, supine cardiac or stroke indexes but in the upright position, the cardiac index and stroke index were higher after volume loading (2.5 +/- 0.7 vs 2.2 +/- 0.5 liters/min/m2, p less than 0.05; 33 +/- 11 vs 27 +/- 9 ml/m2, p less than 0.005, respectively). Although the right atrial, pulmonary arterial and pulmonary capillary wedge pressures were higher during exercise after volume loading, there were no significant differences in exercise heart rate, systemic blood pressure, cardiac index, stroke index, systemic vascular resistance index or overall exercise capacity compared to exercise after diuresis. The data show that the cardiac index and stroke index, at supine rest and during upright exercise, were not influenced by the preload changes induced in these patients with hypertrophic cardiomyopathy. The results suggest that these patients are operating on the plateau of left ventricular Frank-Starling function (filling pressure/output) curve.

Validation and applications of indexed aortic prosthetic valve areas calculated by Doppler echocardiography

Doppler echocardiographic evaluation of aortic valve prostheses is based on the use of variables heretofore validated mostly for native valves. Accordingly, this study examined the validity and relative usefulness of the Doppler valve gradient and area measurements in 31 patients (mean age 69 +/- 10 years) 20 +/- 4 months after implantation of a given type of aortic bioprosthesis ranging in size from 19 to 29 mm. Valve area data obtained with both the standard and simplified continuity equations were compared with known in vitro prosthetic valve area measurements and an excellent correlation was obtained between the standard and simplified continuity equations (r = 0.98, SEE +/- 0.07 cm2, p less than 0.0005) and between in vivo and known in vitro prosthetic valve areas (r = 0.86, SEE +/- 0.16 cm2, p less than 0.0005). Peak gradient ranged from 10.8 to 75.0 mm Hg (mean 35 +/- 16) and mean gradient from 7.6 to 43.7 mm Hg (mean 20.5 +/- 9.5). The correlations between prosthetic valve gradient and in vivo area were r = -0.53, SEE +/- 14 mm Hg and r = -0.49, SEE +/- 8.63 mm Hg for peak and mean gradient, respectively. These relations were improved by indexing valve area by body surface area. The best correlations were obtained between indexed valve area and a quadratic function of the gradient (r = -0.72, SEE +/- 11.72 mm Hg and r = -0.70, SEE +/- 7.28 mm Hg for peak and mean gradient, respectively), reflecting a curvilinear relation.(ABSTRACT TRUNCATED AT 250 WORDS)

Validation and applications of mitral prosthetic valvular areas calculated by Doppler echocardiography

Doppler echocardiography is used in the noninvasive evaluation of mitral valve prostheses using parameters heretofore validated primarily for native valves. Accordingly, this study was designed to examine the validity and relative usefulness of valve gradient and area measurements in a group of 26 patients (17 women, 9 men, mean age 62 +/- 8 years), 19 +/- 4 months after implantation of different sizes (25 to 31 mm) of a given type of bioprosthesis. Areas obtained with both the continuity equation, using stroke volume measured in the left ventricular outflow tract, and the pressure half-time method are compared to known prosthetic areas derived from an in vitro hydraulic model. Areas calculated by the continuity equation correlate well with in vitro areas (r = 0.82, standard error of the y estimate = 0.1 cm2, p less than 0.001), and are within the range of predicted in vitro values in 92% of cases. Areas derived by the pressure half-time method do not correlate with in vitro areas (r = 0.15, p greater than 0.3) or continuity equation areas (r = 0.23, p greater than 0.2), and are above the range of predicted values in 69% of cases. Correlations are also found between continuity equation areas and the peak and mean valvular gradients (r = 0.59, p less than 0.005 and r = -0.63, p less than 0.0005, respectively). Taking the effect of cardiac output on gradients into account results in projected relations between indexed prosthetic areas and the pressure gradients at rest and during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute effects of alcohol and food intake on cardiac performance

Alcohol and food intake induce changes in LV performance which can be evaluated by radionuclide cardiographic methods. Alcohol probably exerts its effects by a direct action of ethanol in the blood on the myocardium, while the postprandial hemodynamic changes are related to the effects of food in the intestine. Alcohol intoxication causes a dose-dependent impairment of LV emptying at rest, whereas compensatory mechanisms other than an increased sympathetic nervous activity counterbalance this effect during exercise. In patients with coronary artery disease, alcohol induces only small changes in LV volumes at rest, possibly because of a concomitant vasodilation. Food intake seems to have a considerable influence on central hemodynamics leading to an increase in cardiac output both in healthy subjects and in patients with coronary artery disease. In healthy subjects an increase is recorded in the LVEDV and LVESV after a meal. The autonomic nervous system is probably responsible for most of the hemodynamic changes.

Radionuclide assessment of left ventricular function during dobutamine infusion in patients with coronary artery disease: comparison with ergometer exercise

The effects of dobutamine on left ventricular function were assessed employing radionuclide ventriculography (RNV) in 7 normal subjects (Group 1) and 21 patients with coronary artery disease (Group 2). After routine bicycle ergometer exercise RNV, dobutamine infusion was started at 5 micrograms/kg/min and the dosage was increased by 5 micrograms/kg/min every 4 minutes to a total of 15 micrograms/kg/min. In Group 1, left ventricular ejection fraction (LVEF) increased by both ergometer exercise and dobutamine infusion. In Group 2, LVEF did not increase during exercise, but increased during dobutamine infusion without evidence of significant myocardial ischemia. Only 2 patients in Group 2 had new regional wall motion abnormality. Left ventricular end-diastolic volume (LVEDV) in Group 2 increased from 191 +/- 19 to 210 +/- 18 ml during ergometer exercise, but decreased from 193 +/- 18 to 153 +/- 19 ml during dobutamine infusion. Short-term low-dose infusion of dobutamine may be used in patients without evidence of significant myocardial ischemia, but probably cannot be substituted for exercise testing in patients with mild to moderate coronary artery disease.

Exercise ultrafast computed tomography for the detection of coronary artery disease

Ultrafast computed tomography permits the assessment of global and regional left ventricular function during exercise. To evaluate the feasibility of using this new technique for the diagnosis of coronary artery disease, 27 patients undergoing cardiac catheterization for diagnosis of chest pain were evaluated. Fifteen patients had significant (greater than 50%) coronary artery stenosis by quantitative coronary angiography. One vessel disease was found in 12 patients and multivessel disease in 3. Fourteen (93%) of the 15 patients with significant coronary stenosis had a decrease in ultrafast computed tomographic ejection fraction during exercise from (mean +/- SD) 65 +/- 7% to 60 +/- 7% (p less than 0.001). The tomographic ejection fraction increased greater than 5% units during exercise in 10 (83%) of the 12 patients with normal coronary arteries. The mean tomographic ejection fraction in this group was 68 +/- 6% at rest and 75 +/- 6% at peak exercise (p less than 0.001). Regional wall motion was quantified by analyzing the segmental ejection fraction of 12 30 degree pie segments at each tomographic level of the left ventricle. A new regional wall motion abnormality developed during exercise in 12 (86%) of 14 patients with coronary artery disease; one patient was excluded because of a technical problem in data storage. Eleven (93%) of the 12 patients with normal coronary arteries had normal wall motion during exercise. In no patient with ischemic heart disease were both variables, ejection fraction response and regional wall motion, normal. Exercise ultrafast computed tomography appears to be a useful technique for the evaluation of coronary artery disease in patients with chest pain and predominant single vessel coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence of exertional right ventricular wall motion abnormalities in patients with coronary artery disease

To evaluate the role of analysis of right ventricular function with exercise in patients with presumed coronary artery disease referred for radionuclide ventriculography, the records of 55 patients referred to our laboratory over a 19-month period were reviewed. All underwent rest and exercise first-pass radionuclide stress testing and cardiac catheterization within a period of four months. Three groups were identified: (1) patients with normal exercise right ventricular function (n = 24); (2) patients with exercise-induced right ventricular regional wall motion abnormalities (n = 15); and, (3) patients with abnormal resting right ventricular function without new exercise abnormalities (n = 16). Patients in each group were similar in age, sex, baseline left ventricular function, medication usage, and indication for study. The incidence of right coronary artery disease was identical in the three groups, as was the incidence of left ventricular functional abnormalities with exercise. Patients with proximal right coronary artery disease were more likely to have reduced left ventricular ejection fraction and more extensive coronary artery disease than those without disease at this site. We conclude that: (1) analysis of rest and exercise right ventricular function does not allow prediction of coronary anatomy in an unselected group of patients; (2) normal right ventricular function with exercise is compatible with extensive coronary artery disease, including proximal right coronary artery disease; and (3) abnormal exercise right ventricular function may be due to exertional left ventricular dysfunction in the absence of proximal right coronary artery disease.

Left ventricular volumes during graded upright exercise in healthy untrained subjects

Left ventricular (LV) volume changes were studied by radionuclide cardiography at rest and during graded upright bicycle exercise in seven healthy untrained men aged 21-30 years. The exercise-induced changes in LV volumes were most pronounced during mild exercise: from rest to 25% submaximal exercise stroke volume increased by 26% and LV ejection fraction from 0.60 to 0.69 (both P less than 0.01), whereas further increments of the work load resulted in only small changes of these variables. LV end-diastolic volume increased initially by 10% (P less than 0.05) but returned to baseline values at higher work loads, whilst a rather constant decrease was recorded in LV end-systolic volume during increasing exercise loads. Changes in plasma catecholamine levels were most pronounced at the high work loads, indicating that these hormones are not directly contributing to the LV volume changes.

Comparison of nifedipine and isosorbide dinitrate when added to maximal propranolol therapy in stable angina pectoris

A study was performed to compare isosorbide dinitrate and nifedipine as adjunctive therapy in 14 patients with coronary artery disease and stable angina pectoris taking maximal beta-blocking drugs. Drug titration phases ensured maximal therapy of propranolol, isosorbide or nifedipine. The combination of nifedipine and propranolol was more effective than the combination of isosorbide and propranolol in reducing angina and increasing exercise capacity (323 vs 416 seconds, p less than 0.005) during exercise treadmill testing. Nifedipine produced a greater reduction in systolic blood pressure at submaximal exercise than isosorbide. Global and regional ejection fraction at rest and exercise was assessed with radionuclide ventriculography. The substitution of nifedipine for isosorbide depressed the global ejection fraction at rest (0.61 to 0.56 p less than 0.05) and produced a slight improvement in exercise ejection fraction (0.47 to 0.51, difference not significant). The decrease in ejection fraction from rest to exercise was 0.14 to 0.04 with nifedipine (p less than 0.005). The benefit of nifedipine compared with isosorbide occurred in regions with marked exercise-induced ischemia. In patients treated with maximal beta-blocking therapy, nifedipine is an effective alternative to isosorbide as a combination agent with propranolol. The salutary effects of nifedipine included afterload reduction with exercise and possible improvements in coronary blood supply.

Effects of beta blockade on systolic and diastolic left ventricular function at rest and during exercise in patients with chronic stable angina pectoris

This study examined the effects of beta blockade with betaxolol, a cardioselective, lipid-soluble, beta-adrenergic-blocking agent, on rest and exercise systolic and diastolic left ventricular function in 15 patients, aged 40 to 70 years (mean = 52), with chronic stable angina pectoris. Each patient underwent three upright exercise studies at identical workloads; the first was a baseline study, the second was done 3 hours after a single oral dose, and the third was obtained after chronic therapy for 2 weeks. Beta blockade was evident by significant decreases in heart rate, systolic blood pressure, and diastolic blood pressure at rest and during exercise (p less than 0.04). Although there were no significant changes (at rest or during exercise) in mean left ventricular ejection fraction and peak filling rate, individual variations were seen after 3 hours and 2 weeks of therapy. During chronic therapy, the peak filling rate increased in three patients, decreased in five, and remained unchanged in seven. Also, discordant changes in systolic and diastolic functions were seen at rest and during exercise during both acute and chronic therapy. Thus, although acute and chronic beta blockade produces no significant changes in mean measurements of diastolic and systolic left ventricular performance, individual variations and discordant results are seen in many patients. The acute effects are generally consistent with the chronic effects, but exceptions are present.

Left ventricular volume during supine exercise: importance of myocardial scar in patients with coronary heart disease

Existing studies suggest that exercise-induced ischemia produces an increase in left ventricular end-diastolic volume; however, all of these studies have included patients with previous myocardial infarction. To test whether the end-diastolic volume response to exercise is related to the extent of myocardial scar, the results of gated radionuclide supine exercise tests performed on 130 subjects were reviewed. The patient group comprised 130 subjects were reviewed. The patient group comprised 130 men aged 35 to 65 years (mean +/- SD 52 +/- 5) with documented coronary heart disease. The extent of myocardial ischemia and scar formation was assessed by stress electrocardiography and thallium-201 scintigraphy. Patients were classified into three groups on the basis of left ventricular end-diastolic volume response at peak exercise: group 1 (n = 72) had an increase of end-diastolic volume greater than 10%, group 2 (n = 41) had a change in end-diastolic volume less than 10% and group 3 (n = 17) had a decrease in end-diastolic volume greater than 10% (n = 17). At rest there was no significant difference among groups in heart rate, systolic blood pressure, end-diastolic (EDVrest) or end-systolic volumes or ejection fraction (p greater than 0.05); however, at peak exercise the end-systolic volume response was significantly greater for group 1 (p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

The role of radionuclide cardiac imaging in coronary artery bypass surgery

The main applications of cardiac nuclear imaging in coronary artery bypass surgery include: patient selection, prediction of improvement in resting LV function after revascularization, diagnosis of perioperative myocardial infarction, assessment of the results of revascularization, evaluation of new or recurrent symptoms, and in risk stratification. Proper understanding of which test to be used, when, and why may be important to optimize patient management.

Determinants of the changes in left ventricular end-diastolic volume during upright exercise in patients with coronary artery disease

We examined the changes in left ventricular (LV) end-diastolic volume (EDV) during symptom-limited upright exercise in 160 patients with coronary artery disease. Patients were divided into three groups based on the degree of exercise-induced LV dilation: group I (n = 66) had no increase in EDV (less than 10% change), group II (n = 38) had mild increase (10% to 24%), and group III (n = 56) had moderate or severe increase (greater than or equal to 25%). The patients with exercise-induced LV dilation had smaller resting EDV (p = 0.0001), higher resting LV ejection fraction (EF) (p = 0.008), and a greater decrease in EF with exercise (delta EF) (p = 0.007). A significant correlation was found between resting EDV and the degree of LV dilation with exercise (r = -0.45, p less than 0.001), and a weaker correlation between the degree of LV dilation and delta EF (r = -0.28, p less than 0.01). Multivariate discriminant analysis of important clinical, anatomic, and exercise descriptors identified three variables that best predicted the presence or absence of LV dilation during exercise: resting EDV (F = 38.2), resting EF (F = 24.2), and delta EF (F = 21.5). Thus, the degree of LV dilation during upright exercise is not related to age, gender, and extent of coronary artery disease, but is determined by the resting EDV, the resting EF, and the EF response to exercise.

Ventricular systolic and diastolic impairment during pacing-induced myocardial ischemia in coronary artery disease: simultaneous hemodynamic, electrocardiographic, and radionuclide angiographic evaluation

This study examined the impairment in systolic and diastolic performance of both ventricles during pacing-induced myocardial ischemia in 12 men with coronary artery disease. Simultaneous hemodynamic, ECG, and radionuclide angiographic assessments were made: pre pacing (pre-P); intermediate pacing (P-1); maximum pacing (P-2); and immediately after pacing (post pacing (P-P). The prepacing measurements were made with the patient in the supine position and during leg elevation. Pacing produced a leftward and upward shift in the diastolic pressure-volume relation, a progressive decrease in left ventricular (LV) end-diastolic volume (p less than 0.003) and right ventricular (RV) end-diastolic volume (p less than 0.01), concomitant with an increase in the pulmonary artery wedge pressure (p less than 0.004) and the right atrial pressure (p less than 0.04). The shift in the LV pressure-volume relation was associated with an initial increase (P-1), followed by a decrease (P-2) in the peak filling rate (p less than 0.001). Pacing also resulted in systolic dysfunction: abnormal LV ejection fraction responses in eight patients, LV regional wall motion abnormalities in eight patients, and abnormal RV ejection fraction responses in seven patients. Leg elevation resulted in a 7% increase in cardiac output, a 20% increase in RV end-diastolic volume, a 28% increase in right atrial pressure, a 29% increase in pulmonary artery wedge pressure, and a 10% increase in LV end-diastolic volume (p less than 0.05). Thus, the ischemic response to pacing results in systolic and diastolic LV and RV dysfunction, with the diastolic impairment being more frequent than the systolic impairment.

Left ventricular pressure/volume relationship in coronary artery disease

This study examined the changes during exercise in LV EF and P/V relationship (systolic blood pressure/end-systolic volume index ratio) in 287 patients. Normal range (mean +/- standard deviation) for exercise EF, exercise P/V, and the changes from rest to exercise (delta) in EF and P/V were established in 51 subjects with less than 1% probability of CAD. The results were compared to those obtained in 53 patients with normal coronary angiograms and 183 patients with angiographically proven CAD. Abnormality in either delta EF or percent delta P/V were observed in 76% of the patients with one-vessel disease and in 91% of patients with multivessel disease. Abnormalities in either delta EF or percent delta P/V were more common than delta EF alone in the total CAD group and in subgroups stratified according to the resting EF, extent of CAD, and adequacy of exercise end points. Similar results were obtained when absolute exercise EF or exercise P/V were used. Abnormalities in the percent delta P/V or delta EF were also seen in 26 of the 53 patients with normal coronary angiograms. Thus, abnormalities in the P/V relationship or EF during exercise are more common than abnormalities in the EF alone. Relative and absolute measurements provide similar results.

Age-related changes in left ventricular diastolic performance

Previous studies show that the radionuclide-derived indices of left ventricular (LV) diastolic performance are abnormal at rest in many patients with coronary artery disease (CAD), even in those with normal resting ejection fraction (EF) and no prior myocardial infarction. This study examined the age-related changes in LV peak filling rate and time to peak filling rate in 65 subjects between the ages of 20 and 75 years with a low likelihood of CAD. All subjects had normal resting EF (greater than or equal to 50%), and none had prior infarction. There was a significant age-related decline in resting peak filling rate (r = -0.47, p less than 0.001) and exercise peak filling rate (r = -0.52, p less than 0.001), but no age-related effect in the time to peak filling rate. Of the 29 subjects less than 50 years of age, 26 (90%) had resting peak filling rate greater than or equal to 2.5 EDV/sec (3.1 +/- 0.6, mean +/- SD) compared to 17 of 36 subjects (47%) greater than or equal to 50 years of age (2.6 +/- 0.6) (p = 0.002). In a subgroup of 28 subjects with a history of hypertension, the age-related effect was more marked than in the remaining 37 subjects without such a history (r = -0.66 vs -0.33). Thus, the peak filling rate at rest and during exercise decreases with advancing age; the high frequency of observed abnormality in the peak filling rate at rest in patients with CAD may conceivably be related in part to age differences between patients with CAD and the control group.

Cardiac function and plasma catecholamines during upright exercise in healthy young subjects

Radionuclide left ventricular ejection fraction, left ventricular volume changes and plasma catecholamines were recorded in six healthy untrained male subjects at rest and during upright exercise at increasing work loads. During mild submaximal exercise mean left ventricular ejection fraction increased 10% because of end-diastolic dilation, while a further 4% increase of left ventricular ejection fraction was recorded at heavy submaximal exercise mainly due to increased end-systolic contraction. Great individual changes were recorded during maximal exercise. Alterations in plasma catecholamines were most pronounced at the high exercise levels indicating that changes in cardiac contractility are not linearly correlated with changes in sympathetic nervous activity. Repeat studies showed only minor variations of mean left ventricular ejection fraction and plasma catecholamines indicating an acceptable reproducibility of the measurements. Variations of both left ventricular ejection fraction and catecholamines were smaller during exercise than at rest.

Left ventricular pressure/volume relationship in aortic regurgitation

In this study we examined the left ventricular pressure/volume relationship in 39 patients with moderate or severe aortic regurgitation (AR) and 15 normal subjects. The patients with AR were divided into two groups; patients with normal resting ejection fraction (EF greater than or equal to 50%, group I, n = 21) and patients with abnormal EF (group II, n = 18). The patients in group I were younger (p less than 0.005), exercised to a higher workload, and had better exercise tolerance than patients in group II (p less than 0.01). The patients' exercise heart rate and blood pressure were not significantly different between the two groups. During exercise tests nine patients in group I and seven patients in group II had normal EF response (greater than or equal to 5% increase) (p = NS). The peak systolic blood pressure to end-systolic volume index ratio (SBP/ESVI) was higher in normal subjects than in patients in groups I and II, at rest it was (4.3 +/- 1.0 vs 2.6 +/- 1.2 vs 1.6 +/- 0.8, respectively, p less than 0.0001) and during exercise it was (7.6 +/- 1.8 vs 4.2 +/- 1.4 vs 2.6 +/- 1.3, respectively, p less than 0.0001). The resting SBP/ESVI ratio was below the lower normal limit in 12 patients (57%) in group I and in 16 patients (89%) in group II. Also, the exercise SBP/ESVI ratio was below the lower normal limit in 17 patients (81%) in group I and all of the patients (100%) in group II. Multivariate discriminant analysis identified the change in SBP/ESVI (F = 34.8) and resting end-diastolic volume (F = 6.7) as independent predictors of the EF response to exercise. Thus, most patients with AR, including those with normal resting EF or normal EF response to exercise, have abnormal SBP/ESVI at rest or during exercise.

Radionuclide evaluation of exercise left ventricular performance in patients with coronary artery disease

Rest and exercise radionuclide angiography is a useful technique to study the cardiac adaptation during exercise in patients with coronary artery disease. Most patients with coronary artery disease have an abnormal EF response to exercise, although the magnitude of the change in EF may not correlate with the extent of coronary artery disease. The resting end-diastolic volume maybe the most important determinant of the presence and degree of left ventricular dilation during exercise in such patients. The exercise left ventricular EF improves after revascularization, but the EF response to exercise often remains abnormal. Evaluation of the regional and global left ventricular performance and the pressure-volume relationship during systole and diastole, as well as changes in these parameters after revascularization are possible. The exercise EF is also an important prognosticator in patients with known or suspected coronary artery disease.

Addition of nifedipine to maximal beta-blocker-nitrate therapy: effects on exercise capacity and global left ventricular performance at rest and during exercise

Nifedipine is a potent coronary vasodilator in the resting state and an effective afterload-reducing agent. This study was undertaken because of the concern that the addition of nifedipine to beta-blocker therapy could produce serious untoward hemodynamic consequences. Although this combination is usually well tolerated, occasional reports suggest that the combination of nifedipine and beta-blocking agents may increase the likelihood of congestive heart failure, severe hypotension or exacerbation of angina. Further, there is a need to know if the addition of nifedipine to therapy with maximally tolerated doses of long-acting nitrates and beta blockers would provide further symptomatic relief without excessive adverse effects. Finally, the effect of adjunctive nifedipine on global left ventricular performance at rest and during exercise was examined. Sixteen patients, all of whom had 3 or more episodes per week of angina pectoris despite therapy with long-acting nitrates and beta blockers, were selected. Radionuclide ventriculography was performed at rest and during exercise; global ejection fractions (EFs) were determined by manually tracing the left ventricular end-diastolic perimeter with an electronic cursor. In the first phase, beta blockers and nitrates were used; in the second phase nifedipine, 10 mg every 6 hours, was added and titrated to reduce systolic blood pressure at rest by at least 10 mm Hg or until intolerable adverse effects occurred. When nifedipine was added to therapy, the difference between global EF at rest and during exercise was reduced from - 0.15 to + 0.02 (p less than 0.00001); exercise duration was increased from 431 seconds to 532 (p less than 0.001), with only 8 patients limited by angina, compared with 16 during the initial therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute effects of alcohol on left ventricular function in healthy subjects at rest and during upright exercise

Six healthy men, aged 23 to 30 years, were studied by radionuclide angiocardiography at rest and at 2 submaximal exercise levels in the upright position during increasing alcohol intoxication. At light intoxication (serum ethanol 23 mmol/liter), the median value of left ventricular (LV) ejection fraction (EF) at rest decreased by 5%. At heavy intoxication (serum ethanol 45 mmol/liter), the median LVEF decreased at rest by 11% and during 75% submaximal exercise by 6%, heart rate at rest increased (median 81 vs 62 beats/min), and systolic blood pressure decreased during 50% submaximal exercise (median 145 vs 163 mm Hg). No significant changes of plasma epinephrine concentrations were recorded, whereas plasma norepinephrine concentrations were increased by 24% at rest during light intoxication and by 30 to 38% during heavy intoxication. No changes of LVEF and plasma catecholamine levels were recorded after ingestion of isovolumic, isocaloric drinks as compared with values obtained before intake. Thus, influences of ingestion per se and repeated investigations of LV function were excluded. These findings suggest that in healthy subjects alcohol intoxication causes a dose-dependent impairment of cardiac contractility. Compensatory mechanisms may account for a reduced influence during exercise.

Radiographic evaluation of the patient with chest pain of suspected myocardial origin

The evaluation of the patient with suspected angina pectoris is discussed and an approach presented which makes use of radiologic tests in conjunction with exercise testing to quickly and efficiently determine the likelihood and severity of coronary artery disease. The relative merits and limitations of chest radiography, cardiac fluoroscopy, nuclear medicine, and coronary arteriography are discussed.