Bernard L. Segal

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.

Usefulness of electrophysiologic testing in evaluation of amiodarone therapy for sustained ventricular tachyarrhythmias associated with coronary heart disease

The prognostic importance of electrophysiologic studies in patients with sustained ventricular tachyarrhythmias treated with amiodarone was prospectively studied in 100 consecutive patients. Sustained ventricular tachycardia (VT)/ventricular fibrillation (VF) was inducible in all patients before amiodarone therapy. After amiodarone administration 2 groups of patients were identified. In group 1 patients the ventricular tachyarrhythmia was no longer inducible and in group 2 patients the arrhythmia remained inducible. In group 1, no recurrent arrhythmia occurred during a follow-up of 18 +/- 10 months. In group 2, 38 of 80 patients (48%) had arrhythmia recurrence during a follow-up of 12 +/- 9 months. The difference between group 1 and 2 could not be explained by clinical variables, amiodarone doses or plasma concentrations, or electrocardiographic variables. In patients in whom cardiovascular collapse or other severe symptoms where noted during electrophysiologic study after amiodarone treatment, recurrences caused sudden death (n = 12). However, in patients in whom the induced arrhythmia produced moderate symptoms, the recurrent arrhythmia was nonfatal VT (n = 26). Electrophysiologic testing provides clinical guidance and predicts prognosis in patients treated with amiodarone as it does for the evaluation of other antiarrhythmic agents.

Noninvasive evaluation of normal and abnormal prosthetic valve function.

Noninvasive techniques are helpful in evaluating the function of mechanical prostheses and tissue valves. Combined phonocardiography and M-mode echocardiography together with cinefluoroscopy are the most useful noninvasive techniques in differentiating normal from abnormal metallic prosthetic valve function. The intensity of the opening and closing clicks and associated murmurs will depend on the type of prosthetic valve, the heart rate and rhythm and the underlying hemodynamic status. Arrhythmias or conduction disturbances, or both, may produce motion patterns that mimic some of the echocardiographic signs of malfunctioning prosthetic valves. Differentiation of thrombus formation or tissue ingrowth from paravalvular regurgitation or dehiscence is possible by noninvasive techniques. Disc variance, a potentially serious and lethal problem with the older Beall valves, can be readily detected by cinefluoroscopy and echophonocardiography. With regard to bioprosthetic valves, two-dimensional echocardiography is superior to M-mode echocardiography in detecting primary valve failure. In addition, detection of vegetations, valve alignment and ring and individual leaflet motion can be best accomplished by two-dimensional echocardiography. Of greater importance is the patient serving as his or her own control in the follow-up assessment of prosthetic valve function by noninvasive techniques.

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.

Progression of isolated aortic stenosis: Analysis of 29 patients having more than 1 cardiac catheterization

Factors related to progression of nonrheumatic aortic stenosis (AS) were analyzed in 29 adult patients who underwent serial hemodynamic studies over a mean of 71 months. AS was congenital in 8 patients and degenerative in 21. The patients were divided into 2 groups on the basis of the change in aortic valve area between the 2 studies. Twelve patients had a greater than or equal to 25% reduction in aortic valve area (Group I) and 17 patients had less than 25% decrease in aortic valve area (Group II). There were no significant differences between the 2 groups in age, interval between studies, cardiac output, left ventricular end-diastolic pressure, left ventricular peak systolic pressure and origin of AS (congenital or degenerative). Group I patients had significantly larger initial aortic valve areas than did Group II patients (1.3 +/- 0.9 cm2 versus 0.8 +/- 0.4 cm2, p = 0.02). Also, the initial peak transaortic pressure gradients were lower in Group I than in Group II (27 +/- 19 versus 58 +/- 38 mm Hg, p = 0.01). Group I patients had a significantly greater increase in pressure gradient and a greater reduction in cardiac output than did Group II patients (24 +/- 21 mm Hg in Group I versus -0.1 +/- 24.5 mm Hg in Group II, p = 0.01, and -1.0 +/- 1.3 liters/min in Group I versus 0.10 +/- 1.4 liters/min in Group II, p = 0.03). Thus, AS progressed in 41% of a selected group of patients who underwent repeated cardiac catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)

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

Radionuclide angiography permits evaluation of left ventricular performance during exercise. There are several factors that may affect the results in normal subjects and in patients with chronic coronary heart disease. Important among these are the selection criteria: age, sex, level of exercise, exercise end points, ejection fraction at rest and effects of pharmacologic agents. An abnormal ejection fraction response to exercise is not a specific marker for coronary heart disease but may be encountered in other cardiac diseases. In addition to the diagnostic considerations, important prognostic data can be obtained. Further studies are needed to determine the prognostic implications of anatomic findings versus the functional abnormalities induced by exercise in patients with coronary artery disease.

Tricuspid regurgitation: Noninvasive techniques for determining causes and severity

Tricuspid regurgitation is often not apparent on physical examination and several methods are now available to aid in this difficult assessment. Cardiac catheterization using right ventriculography, previously considered the diagnostic standard, has several limitations. Currently available noninvasive tools such as M-mode and two-dimensional echocardiography (with or without contrast), Doppler techniques and even radionuclide cardiologic imaging have added significantly to the precise assessment of the presence and severity of tricuspid regurgitation. This review examines the comparative use and limitations of these various techniques.

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.