Sally A. Kane

Rest and redistribution thallium-201 myocardial scintigraphy to predict improvement in left ventricular function after coronary arterial bypass grafting

To examine the value of rest and redistribution thallium-201 imaging in predicting improvement in left ventricular (LV) ejection fraction (EF) after coronary artery bypass grafting (CABG), 26 patients with coronary artery disease (CAD) and abnormal LV function were studied. Nineteen patients had pathologic Q waves preoperatively. Rest and redistribution thallium-201 images and radionuclide ventriculograms were obtained before and after CABG, and the thallium scintigrams were evaluated both quantitatively and qualitatively. The patients were divided according to the preoperative thallium scintigrams into 2 groups: Group I (16 patients) had either normal resting thallium-201 images or reversible resting perfusion defects, and Group II (10 patients) had fixed resting perfusion defects. The resting EF was less than 50% preoperatively in all patients. Fourteen patients (54%) showed improvement in EF postoperatively. Three patients (2 in Group I and 1 in Group II) showed new postoperative perfusion defects, and none of the 3 showed improvement in LV function. Of the remaining 14 patients in Group I, 12 (86%) showed improvement in LV function, compared with 2 of 9 patients in Group II (p less than 0.01). Improvement in LV function was observed in 8 of the 19 patients (42%) with abnormal Q waves. Nitroglycerin intervention radionuclide ventriculograms were obtained in 20 patients before CABG. Of the 6 patients who showed improvement in LV function with nitroglycerin, 4 also showed improvement postoperatively. Postoperative improvement in LV function was also observed in 6 of the 14 patients who did not improve with nitroglycerin. Thus, rest and redistribution thallium imaging is useful in identifying patients whose LV function will improve after CABG. Normal rest thallium-201 images or reversible resting defects correctly identified 12 of 14 patients (86%) who showed improvement in LV function postoperatively. Nitroglycerin-intervention ventriculography and abnormal Q waves were less useful in this differentiation.

Reliability of bedside evaluation in determining left ventricular function: Correlation with left ventricular ejection fraction determined by radionuclide ventriculography

Ninety-nine patients with chronic coronary artery disease were prospectively evaluated to determine the reliability of historical, physical, electrocardiographic and radiologic data in predicting left ventricular ejection fraction. The left ventricular ejection fraction measured by radionuclide angiography was normal (greater than or equal to 50%) in 44 patients (group 1) and abnormal (less than 50%) in 55 patients; 36 of those 55 patients had an ejection fraction between 30 and 49% (group 2) and the remaining 19 patients had an ejection fraction of less than 30% (group 3). The ejection fraction was correctly predicted in 33 of the 44 patients (75%) in group 1 and in 47 of the 55 patients (85%) with abnormal ejection fraction (groups 2 and 3), but the degree of ventricular dysfunction was correctly predicted in only 19 patients (53%) in group 2 and in only 9 patients (47%) in group 3. Stepwise linear regression analysis was performed. The single most predictive variable was cardiomegaly as seen on chest roentgenography (R2 = 0.52). Four optimal predictive variables--cardiomegaly, myocardial infarction as seen on electrocardiography, dyspnea and rales--could explain only 61% of the observed variables in left ventricular ejection fraction. Thus, radionuclide ventriculography adds significantly to the discriminant power of the clinical, radiographic and electrocardiographic characterization of ventricular function in patients with chronic coronary heart disease.

Value of left ventricular ejection fraction during exercise in predicting the extent of coronary artery disease

To determine the relation between left ventricular performance during exercise and the extent of coronary artery disease, the results of exercise radionuclide ventriculography were analyzed in 65 patients who also underwent cardiac catheterization. A scoring system was used to quantitate the extent of coronary artery disease. This system takes into account the number and site of stenoses of the major coronary vessels and their secondary branches. The conventional method of interpreting the coronary angiograms indicated that 26 patients had significant coronary artery disease (defined as 70% or more narrowing of luminal diameter) of one vessel, 21 had multivessel disease and 18 had no significant coronary artery disease. Although the exercise left ventricular ejection fraction was significantly higher in patients with no coronary artery disease than in patients with one or multivessel disease (probability [p] less than 0.001), there was considerable overlap among the three groups. With the scoring system, a good correlation was found between the coronary artery disease score and the exercise left ventricular ejection fraction (r = -0.70; p less than 0.001). If the exercise heart rate was 130 beats/min or greater or the age of the patient was 50 years or less, an even better correlation was found (r = -0.73 and r = -0.82, respectively). The exercise ejection fraction (but not the change in ejection fraction, end-diastolic volume and end-systolic volume from rest to exercise) correlated with the extent of coronary artery disease. The exercise ejection fraction is the most important exercise variable that correlates with the extent of coronary artery disease when the latter is assessed quantitatively by a scoring system rather than the conventional method of reporting coronary angiograms. Young age and greater exercise heart rate strengthened the correlation. The change in ejection fraction from rest to exercise is useful in the diagnosis of coronary artery disease, but it was the absolute level of exercise ejection fraction that predicted the extent of disease.

Left ventricular end-systolic pressure-volume relation. A combined radionuclide and hemodynamic study.

Abstract This study examines the effect of increasing heart rate by atrial pacing on the left ventricular endsystolic pressure-volume relation and determines whether peak pressure can be used instead of end-systolic pressure. Measurements were made of cardiac output (by thermodilution), pulmonary arterial pressure, ejection fraction (by radionuclide angiography), and aortic pressure (by intraarterial catheter). End-systolic pressure was measured at the dicrotic notch. The end-diastolic and end-systolic volumes were determined from the ejection fraction and cardiac output. There was excellent correlation in pressure-volume relation determined by peak pressure and end-systolic pressure (r = 0.95). In 8 normal subjects there was

Two-dimensional echocardiographic estimation of right ventricular ejection fraction in patients with coronary artery disease

Two-dimensional echocardiographic determination of right ventricular ejection fraction was compared with right ventricular ejection fraction obtained by first pass radionuclide angiography in 39 patients with coronary artery disease. Apical four chamber and two chamber right ventricular views were obtained in 34 (87%) of the 39 patients, while a subcostal four chamber view was obtained in 31 patients (80%). Right ventricular ejection fraction by two-dimensional echocardiography was calculated by the biplane area-length and Simpsons rule methods using two paired orthogonal views and utilizing a computerized light-pen method for tracing the right ventricular endocardium. A good correlation (r = 0.74 to 0.78) was found between radionuclide angiographic and two-dimensional echocardiographic right ventricular ejection fraction for each method used. Patients with acute inferior myocardial infarction had the lowest right ventricular ejection fraction by radionuclide angiography and two-dimensional echocardiography (p less than 0.05 compared with patients with right coronary artery obstruction and no infarction). There were no differences in right ventricular ejection fraction between patients with acute and old inferior myocardial infarction by both techniques. No correlation was found between left and right ventricular ejection fraction by radionuclide angiography (r = 0.16). It is concluded that 1) right ventricular ejection fraction by two-dimensional echocardiography correlates well with radionuclide angiographic measurements and can reliably evaluate right ventricular function in coronary artery disease, 2) patients with inferior myocardial infarction have reduced right ventricular ejection fraction, and 3) changes in left ventricular ejection fraction do not directly influence right ventricular function.

Left ventricular function in chronic aortic regurgitation

Left ventricular performance was determined in 42 patients with moderate or severe aortic regurgitation during upright exercise by measuring left ventricular ejection fraction and volume with radionuclide ventriculography. Classification of the patients according to exercise tolerance showed that patients with normal exercise tolerance (greater than or equal to 7.0 minutes) had a significantly higher ejection fraction at rest (probability [p] = 0.02) and during exercise (p = 0.0002), higher cardiac index at exercise (p = 0.0008) and lower exercise end-systolic volume (p = 0.01) than did patients with limited exercise tolerance. Similar significant differences were noted in younger patients compared with older patients in ejection fraction at rest and exercise (both p = 0.001) and cardiac index at rest (p = 0.03) and exercise (p = 0.0005). The end-diastolic volume decreased during exercise in 60% of the patients. The patients with a decrease in volume were significantly younger and had better exercise tolerance and a larger end-diastolic volume at rest than did patients who showed an increase in volume. The mean corrected left ventricular end-diastolic radius/wall thickness ratio was significantly greater in patients with abnormal than in those with normal exercise reserve (mean +/- standard deviation 476 +/- 146 versus 377 +/- 92 mm Hg, p less than 0.05). Thus, in patients with chronic aortic regurgitation: 1) left ventricular systolic function during exercise was related to age, exercise tolerance and corrected left ventricular end-diastolic radius/wall thickness ratio, and 2) the end-diastolic volume decreased during exercise, especially in younger patients and patients with normal exercise tolerance or a large volume at rest.

Correlation among right ventricular preload, afterload and ejection fraction in mitral valve disease: radionuclide, echocardiographic and hemodynamic evaluation

The relation among right ventricular preload, afterload and ejection fraction in patients with mitral valve disease has not been well elucidated. In this study, measurements were made of intracardiac pressures and forward cardiac output during cardiac catheterization (n = 43), the ejection fraction by radionuclide angiography (n = 43) and end-systolic radius and wall thickness by M-mode echocardiography (n = 22). There was a linear correlation between pulmonary artery pressure and right atrial pressure (r = 0.57, p less than 0.01). The right ventricular peak circumferential systolic wall stress was increased in 68% of the patients (in comparison with wall stress measurements obtained in 10 normal subjects). The right ventricular ejection fraction was abnormal in 38 patients (88%) and abnormal in 14 of the 15 patients with high wall stress. There was an inverse correlation between ejection fraction and end-diastolic volume (r = -0.61, p less than 0.001). The right ventricular ejection fraction measurement was repeated within 3 months after mitral valve replacement in 16 patients; the ejection fraction increased from 21 +/- 9 to 29 +/- 10% (mean +/- standard deviation) after surgery (p less than 0.01), but normalization of the ejection fraction was observed in only 3 patients (19%). Thus, abnormal right ventricular ejection fraction, which is observed in most patients with rheumatic mitral valve disease, results from inappropriate wall stress or depressed inotropic response of the right ventricle due to damage. Right ventricular dilation appears to be a compensatory mechanism to maintain the cardiac output.

Correlation between changes in R wave amplitude and left ventricular volume induced by rapid atrial pacing

To examine the Brody effect in humans, we studied 15 patients by means of coronary sinus pacing. We measured left ventricular (LV) volumes from the cardiac output (measured by the thermodilution technique) and LV ejection fraction (measured by radionuclide ventriculography). Pulmonary blood volume was determined by means of cardiac output and mean pulmonary transit time. In six patients, pacing was performed at two different rates, resulting in 21 pacing measurements. The heart rate increased with pacing from 73 +/- 11 to 119 +/- 19 bpm (mean +/- standard deviation, p less than 0.001). The end-diastolic volume (EDV) and the end-systolic volume (ESV) decreased with pacing (p less than 0.001 each). The R wave amplitude decreased with pacing (1.44 +/- 0.63 mV control vs 1.32 +/- 0.58 mV with pacing; p less than 0.01). R wave amplitude decreased in 19 of the 21 pacing studies (90%); EDV and ESV decreased in all 21 pacing studies, and pulmonary blood volume decreased in 14 of the 15 pacing studies (93%) performed in 11 patients. There was a significant correlation between the percentage of change in R wave amplitude with the percentage of change in EDV (r = 0.54, p less than 0.01) and with the percentage of change in ESV (r = 0.54, p less than 0.01). These results, therefore, validate Brodys hypothesis and indicate that changes in LV volumes affect the R wave amplitude.

Cardiac performance in thyrotoxicosis: analysis of 10 untreated patients.

This study attempts to define cardiac performance at rest and during exercise in patients with untreated thyrotoxicosis. We studied 7 women and 3 men, aged 23 to 59 years (40 +/- 10, mean +/- standard deviation [SD]) and compared the results with those obtained in 12 normal subjects. In patients with thyrotoxicosis, the rhythm was sinus and the only untoward symptom was palpitations; the resting electrocardiographic results were normal in 8 patients and showed left ventricular hypertrophy in 2 patients; the left ventricular ejection fraction and volumes (measured by radionuclide ventriculography) were normal at rest. During exercise, 1 patient had dyspnea and 7 had leg fatigue; 2 were asymptomatic. Also, 7 patients had greater than or equal to 5% increase in left ventricular ejection fraction, 2 had no change, and 1 had a decrease. In all 10 patients, the exercise ejection fraction was greater than or equal to 60%. All normal subjects had a greater than or equal to 5% increase in ejection fraction during exercise. There were no significant differences at rest between patients with thyrotoxicosis and normal subjects in blood pressure, ejection fraction, end-diastolic volume, stroke volume, end-systolic volume, or cardiac output, but the heart rate was significantly higher in patients with thyrotoxicosis (91 +/- 10 versus 80 +/- 12 beats/min, p less than 0.05). During exercise, there were no significant differences between patients with thyrotoxicosis and normal subjects in blood pressure, end-diastolic volume, stroke volume, end-systolic volume, or cardiac output. The exercise ejection fraction was significantly lower in patients with thyrotoxicosis than in normal subjects (68 +/- 10% versus 75 +/- 4%, p less than 0.05). Cardiac performance is normal at rest in patients with thyrotoxicosis, but during exercise abnormal left ventricular reserve occurs in some patients.

Thallium-201 myocardial scintigraphy and left ventricular function at rest in patients with rest angina pectoris

The purpose of this study was to examine the rest thallium-201 perfusion pattern during angina-free periods in 40 patients with rest angina pectoris secondary to coronary artery disease (greater than or equal to 70% diameter narrowing). Seventeen patients had previous Q wave myocardial infarction. The perfusion defects were considered fixed or reversible, depending on the absence or presence of redistribution in the 4-hour delayed images. There were 40 perfusion defects (26 fixed and 14 reversible) in 27 patients whereas 13 patients had normal scans. Reversible perfusion defects were present in 10 patients (25%). Of the 26 fixed perfusion defects, 17 did not have corresponding Q waves. Occluded vessels (63%) had more perfusion defects than vessels with subtotal occlusion (30%) (p less than 0.01). The perfusion defect size was larger in patients with lower ejection fraction than in patients with higher ejection fraction. We conclude: (1) perfusion defects are common in patients with rest angina and are reversible in 25% of patients indicating reduced regional coronary blood flow; (2) the degree of stenosis affects the presence of perfusion defect; (3) fixed defects may be present without corresponding Q waves; and (4) global left ventricular function is related to the size of perfusion defects.