Left ventricular aneurysm and prognosis after first anterior wall acute myocardial infarction.
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Follow-Up Studies↗
Biomedical subjects
S F Horowitz
Publications and source records attributed to S F Horowitz.
Exercise-induced pulmonary blood volume changes and diastolic dysfunction of the aged heart.
Impaired diastolic function has been described in healthy elderly subjects. Pulmonary blood volume (PBV) changes with exercise have been associated with left ventricular dysfunction, but not directly related to diastolic abnormalities. Exercise-induced relative changes in PBV were measured using gated blood pool imaging with count density comparisons over the lung in 20 healthy volunteers: 13 elderly, age 76 +/- 5 years and seven young, age 27 +/- 4 years. Serial (first exercise stage, peak exercise, and post exercise) PBV ratios were measured and correlated to peak early filling rate, peak late filling rate, and percent atrial filling obtained from the resting left ventricular time-activity curve analysis. PBV ratios tended to be higher in elderly subjects, but reached significance only at the first stage of exercise (1.04 +/- 0.07 vs. 0.93 +/- 0.10, p less than 0.01). Significant correlations were found between PBV ratios at first exercise stage and peak early filling rate (r = -0.64), peak late filling rate (r = 0.47), and percent atrial filling (r = 0.48). A significant correlation was found between PBV changes at peak exercise and resting diastolic parameters. Exercise-induced PBV changes are associated with left ventricular diastolic dysfunction at rest. Diastolic abnormalities of the aged heart may explain the differential PBV response early into exercise between young and elderly healthy subjects.
Adult↗
Importance of epidemiology and biostatistics in deciding clinical strategies for using diagnostic tests: a simplified approach using examples from coronary artery disease.
The explosion of costly new medical diagnostic technologies demands a common sense approach to help physicians decide appropriate indications and strategies for use of these tests. This simple, nonmathematical review focuses on the assessment of coronary artery disease, but the approach can be generalized to other medical problems. This clinical approach to diagnostic testing strategies is based on seven sequential questions: 1. What is the clinical probability that this patient has a specific disease characteristic based on clinical data? 2. What is the overall objective for management of this patient based on the overall status of the patient? 3. Most importantly, what specific questions need to be answered about the patient's condition before the physician can recommend the most appropriate management (e.g., whether the patient has coronary disease, whether an anatomic lesion is functionally significant, whether a myocardial region is reversibly ischemic or irreversibly infarcted, whether a particular therapy has had good or bad effects or what is the patient's prognosis)? The key point is for the physician to formulate a specific clinical question about the patient before the test. 4. The physician must then ask how well does the test answer the particular clinical question about the patient. Here the physician needs to understand the sensitivity and specificity of the test, especially because they are influenced by various clinical biases. 5. Next, the physician must ask how to interpret the reliability of a positive or negative test result in the individual patient. This requires understanding predictive value and predictive error of a given result and how they are influenced by the clinical data as described by Bayes' theorem. 6. Next, the physician must ask what further tests or therapies will be recommended for the patient. The physician can estimate in advance how different test results would alter management plans and he can then allow this estimate to help determine indications for the test. There is some controversy concerning whether to use Bayes' theorem or multivariate analysis to estimate the final probability of a disease characteristic. 7. Finally, in this era of quality assurance, professional review and cost containment, it behooves each physician to ask whether the data provided by the particular tests were worth the cost, inconvenience and risk for that particular patient.
Bayes Theorem↗
Peripartum cardiomyopathy. A role for cardiac stress determinants other than pregnancy?
Peripartum cardiomyopathy is a syndrome of undetermined etiology whose most common initial symptoms are those of congestive heart failure. The syndrome carries a five-year mortality estimated at 40%. Single noxious factors, such as viral infection, have been proposed as direct precipitants of this syndrome, but none have been conclusively linked to it. The cases of two patients with identifiable cardiac stress factors who developed peripartum cardiomyopathy are presented here: one with sepsis complicated by disseminated intravascular coagulopathy and severe anemia, and a second with an otherwise normal pregnancy who engaged in strenuous aerobic exercise throughout the last trimester. A review of previously published cases reveals the frequent association of multiple nonspecific cardiac stress factors that may predispose women to peripartum cardiomyopathy. Various cardiac stress factors may act synergistically with the stress of pregnancy to precipitate peripartum cardiomyopathy in susceptible women.
Adolescent↗
The role of ischemia and ventricular asynergy in the genesis of exercise-induced ST elevation.
Sixty-five patients with ST elevation were retrospectively studied in order to evaluate the clinical significance and underlying mechanisms of ST-segment elevation during exercise. Of these, 50 patients had previous myocardial infarction (Group I) and 15 patients did not (Group II). Exercise thallium-201 imaging was performed on 30 patients, resting gated blood pool imaging was performed on 33 patients, and 23 underwent cardiac catheterization for clinical indications. When the two groups were compared, patients in Group I had more frequent multivessel disease (9/13 vs. 3/10, p less than 0.05), anterior infarctions (33/50 vs. 4/10, p less than 0.02), while Group II patients had more frequent single-vessel disease (7/10 vs. 4/13, p less than 0.05). For Group I patients, the most common reason for termination of exercise was fatigue and/or dyspnea (35/50 vs. 0/15, p less than 0.05), with an irreversible defect noted in both stress and delayed views on thallium imaging (20/24 vs. 1/6, p less than 0.05). In Group II, the most common reason for termination was angina (15/15 vs. 2/50, p less than 0.001), with reversible thallium defects noted more frequently (4/6 vs. 3/24, p less than 0.01). Thus, we conclude that in patients with Q waves, left ventricular dysfunction rather than ischemia is the mechanism for ST elevation. In these patients angina is rare, but fatigue, dyspnea, multivessel disease, and fixed thallium defects are common. In patients with non-Q-wave exertional ST elevation, ischemia is the rule, manifested by frequent chest pain and reversible thallium defects.
Adult↗
Serial pulmonary blood volume changes with supine exercise in normal subjects and in coronary artery disease patients.
Relative changes in pulmonary blood volume (PBV) were assessed serially at first stage, peak and post-supine exercise in 13 young normal volunteers and 33 coronary artery disease (CAD) patients. Gated blood pool imaging was used with time corrected count calculation of a region over the lung and comparison to the rest image. In normal subjects, the PBV ratio did not change with exercise but dropped significantly immediately post-exercise. In CAD patients, the PBV ratio increased in the first exercise stage, increased further at peak exercise, and fell significantly following exercise cessation. In the three stages studied, significantly higher PBV ratios were demonstrated in the CAD patients compared to normal subjects, but with significant overlap between the two groups. No significant relation was found between PBV changes and the number of diseased vessels, severity score (Gensini), left ventricular end-diastolic pressure, exercise-limiting symptoms, and left and right ventricular ejection fraction at rest and with exercise. Despite the different response of the PBV ratio to exercise between normals and CAD patients, a significant overlap limits the value of this ratio as a discriminator of the presence, severity or location of CAD.
Adult↗
Evaluation of right and left ventricular function in hard metal workers.
Ingested cobalt has previously been associated with the development of a congestive cardiomyopathy. Despite occasional reports of cardiomyopathy after industrial exposure to cobalt, this association remains controversial. In a study of 30 cemented tungsten carbide workers with a mean duration of exposure to cobalt of 9.9 +/- 5.3 years radionuclide ventriculography was performed to study right and left ventricular ejection fractions at rest and exercise. For the entire group, rest and exercise biventricular function was normal. There was, however, a weak but significant inverse correlation between duration of exposure and resting left ventricular function (r = -0.40, p less than 0.03). Workers with abnormal chest x ray findings (9/30) had relatively lower exercise right ventricular ejection fractions (45% +/- 6 v 52% +/- 7, p less than 0.02). An inverse relation was also found between rest and exercise right ventricular ejection fraction and severity of parenchymal abnormalities on x ray examination (r = -0.44, p less than 0.01 and r = -0.41, p less than 0.02). Diminished right ventricular reserve was probably due to fibrotic lung disease and early cor pulmonale. Although overt left ventricular dysfunction was not present, prolonged exposure to industrial cobalt may be a weak cardiomyopathic agent with unknown long term significance.
Adult↗
Relation of late potentials to ejection fraction and wall motion abnormalities in acute myocardial infarction.
A prospective study was performed to determine the relation between quantitative signal-averaged parameters and ejection fraction (EF) and wall motion abnormalities determined by radionuclide ventriculography in patients with acute myocardial infarction (AMI). In 50 patients with AMI, signal-averaging of the surface QRS complex (200 beats; filter frequencies of 40 to 250 Hz and 80 to 250 Hz) was performed and radionuclide ventriculograms were recorded 8 +/- 5 days after AMI. Twenty-five of these patients (50%) had anterior wall AMI, 20 (40%) had inferior wall AMI and 5 (10%) had non-Q-wave AMI. The duration of the low-amplitude signals of less than 40 microV, the signal-averaged QRS complex and the root-mean-square voltage of the terminal 40 ms were determined. In addition to EF determinations, wall motion abnormalities were assessed for the presence or absence of dyskinetic, akinetic and hypokinetic segments. A wall motion score was constructed by separating the left and right ventricles into 21 segments in the anterior, left anterior oblique and lateral views. On the basis of the presence or absence of late potentials, the patients were separated into 2 groups: group I comprised 15 patients (30%) with late potentials and group II 35 patients (70%) without late potentials. The low-amplitude signals (49 +/- 12 vs 24 +/- 8 ms) and the signal-averaged QRS complex (122 +/- 20 vs 96 +/- 15 ms) were significantly longer and the root-mean-square voltage (13.8 +/- 4.9 vs 54.3 +/- 27.4 microV) significantly lower in group I than in group II.(ABSTRACT TRUNCATED AT 250 WORDS)
Action Potentials↗
The effect of heart rate and contractility on the measurement of left ventricular mass by 201Tl SPECT.
Left ventricular myocardial mass can be measured by 201Tl SPECT, but the effects of changes in heart rate and contractility have not been determined. We constructed a dynamic computer model simulating the contracting left ventricle. Thirty two summed static views at each of 3 heart rates and 3 ejection fractions were manufactured to simulate a 180 degrees acquisition. Each image set underwent tomographic reconstruction. Left ventricular mass was measured at a fixed percent threshold in each slice. The results show that left ventricular mass varied little with heart rate (4%) and only slightly more (8%) with ejection fraction. Thus, in the normal clinical setting, left ventricular mass measurements by SPECT are minimally affected by the dynamic state of the heart.
Computer Simulation↗
Atrial kinetics and left ventricular diastolic filling in the healthy elderly.
A delay of left ventricular isovolumic relaxation and decrease in myocardial compliance may result in a decline of measured early filling rates in elderly subjects. Previous studies of diastolic function, however, have not excluded coronary artery disease or addressed the contribution of atrial contraction to diastole. The present study evaluated radionuclide-derived diastolic variables in 13 healthy elderly volunteers aged 75 +/- 6 years without symptoms or risk factors for coronary disease who had normal findings on the stress electrocardiogram, stress gated blood pool imaging and two-dimensional echocardiogram. Results were compared with those of a group of 10 healthy young volunteers aged 26 +/- 5 years. High count, 32 frame, double-buffered gated blood pool acquisitions were obtained at rest in the left anterior oblique view with an RR interval variation less than 5%. Left ventricular time-activity curves were analyzed and flow-volume loops for each group were constructed. In the healthy elderly: peak early diastolic filling rate is decreased, time of peak early filling and time to first third of diastolic filling are delayed, and peak late left ventricular filling rate and percent of atrial filling volume are augmented, suggesting an adaptive response of the atria to diminished left ventricular compliance.
Aged↗
The relationship of dyspnea on exertion to stress-induced thallium-201 lung uptake.
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Adult↗
Left ventricular pseudoaneurysm causing superior vena caval obstruction and effusive-constrictive pericarditis.
A diabetic woman with a silent myocardial infarction on clinical and electrocardiographic criteria presented with findings on physical examination of superior vena caval obstruction and effusive-constrictive pericarditis. A left ventricular posterior wall pseudoaneurysm and intrapericardial hematoma were found, with extrinsic compression of the right atrium. The diagnosis was first suspected by radionuclide imaging and confirmed by contrast angiography and surgery.
Aged↗
Vertical left ventricular angulation assessed by thallium 201 myocardial perfusion imaging in patients with mitral valve prolapse.
Mitral valve prolapse has been associated with septal to aortic root angle abnormalities determined by echocardiography. Thallium 201 imaging in the anterior view permits visualization of the left ventricular long axis. In the present study, the vertical angle was defined as the angle formed by the long axis of the left ventricle and a horizontal line. The vertical angle was determined in 25 patients who had 201 TL stress testing and M-mode echocardiography. Group I (11 patients) had mitral valve prolapse and group II (14 patients) did not have mitral valve prolapse. The vertical angle and ultrasound were read blinded to each other. Height, weight, and body surface area were compared for the two groups, and receiver operator curve analysis performed. Vertical angle measured by TL 201 was significantly more vertical in patients with mitral valve prolapse. Receiver operator curve analysis showed that an angle of greater than 30 degrees successfully identified 9/11 patients with mitral valve prolapse, with a sensitivity of 82% and a specificity of 79%. There were no significant differences in height, weight, or body surface area between the two groups. Thus, patients with mitral valve prolapse have more vertically positioned hearts than patients without mitral valve prolapse, independent of body habitus. The different appearance of a vertically oriented heart may contribute to false-positive readings of TL 201 images.
Adult↗
Gated blood pool scintigraphic monitoring of doxorubicin cardiomyopathy: comparison of camera and computerized probe results in 101 patients.
Serial gated blood pool scintigraphic monitoring of cardiac function with both a nonimaging scintillation probe and a conventional gamma camera-computer imaging system was performed in 101 patients receiving doxorubicin hydrochloride (Adriamycin) chemotherapy. Comparison of probe- and camera-derived ejection fractions (n = 287) correlated significantly (r = 0.70, p less than 0.005) as did the interstudy (n = 183) change in ejection fraction (r = 0.76, p greater than 0.005). Significant discordance in probe- and camera-derived ejection fraction change occurred in 3 (1.6%) of 183 interstudy intervals. Average intrastudy variability of absolute probe-derived ejection fraction was 2.9%. This variability was unrelated to the level of cardiac function. Thirteen patients (13%) developed clinical cardiotoxicity, including four at cumulative Adriamycin levels less than 450 mg/m2. Mean absolute camera ejection fraction decline for these patients was 21% from baseline evaluation, and mean absolute probe ejection fraction decline was 22%. The minimal absolute ejection fraction decline was 11% for patients with clinical congestive heart failure. Eight asymptomatic patients had therapy terminated before the development of clinical cardiotoxicity after a mean decline in absolute camera ejection fraction of 19 +/- 4% (SD) and in probe ejection fraction of 19 +/- 9% into abnormal ranges (a decline in magnitude equivalent to that in patients developing congestive failure). None of these five asymptomatic patients available for clinical follow-up at 6 months after termination of Adriamycin therapy subsequently developed signs of ventricular dysfunction. The majority of patients (83%) studied at 450 mg/m2 cumulative dose levels did not have a 15% or greater decline from baseline into the abnormal range.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Abnormalities of the ascending aorta detected by gated blood pool imaging.
Radionuclide angiography has been used for visualization of aortic arch pathology. Gated blood pool scintigraphy generally has been reserved for the evaluation of ventricular function. By observing the aorta in relation to other cardiac structures, additional information about relative size and shape is available, and can be integrated with ventriculographic observations. This may enhance understanding of the mechanism of disease in the individual patient. Five selected case histories illustrating this point are presented. The last example demonstrates the ability of the technique to uncover unsuspected thoracic aorta pathologic findings. The sensitivity and specificity of this technique to diagnose aortic disease requires further study.
Adult↗
Hard metal disease: a multidisciplinary evaluation of two cases.
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Adult↗
Exercise-induced regional wall motion abnormalities: how specific a marker for coronary artery disease?
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Adult↗
Computer modeling of planar myocardial perfusion imaging: effect of heart rate and ejection fraction on wall thickness and chamber size.
Myocardial perfusion imaging is generally performed as a static acquisition without regard for dynamic changes in the cardiac cycle. The effect of heart rate and ejection fraction on the appearance of left ventricular chamber size and wall thickness as perceived in 201Tl scintigrams has not, to our knowledge, been previously studied. A dynamic computer model of the left ventricle was constructed, capable of varying the heart rate and ejection fraction. Parallel slices through the model were convolved with experimentally derived 201Tl point spread functions at corresponding depths to incorporate the effects of scatter and attenuation. Both gated and static left anterior oblique images were created at three clinically encountered heart rates and ejection fractions, with constant end-diastolic volume and left ventricular mass. Results of the study indicate that perceived and quantified wall thickness increases and chamber size decreases appreciably with increasing ejection fraction and (slightly) with increasing heart rate. Thus, evaluation of wall thickness and chamber size in planar images should take into account variations in heart rate and contractility. This is especially pertinent to estimates of left ventricular hypertrophy and chamber size, attempted from nongated myocardial perfusion images.
Computers↗