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Oncocytoma of the salivary glands is a rare tumor that usually follows a benign course and, in most cases, can be cured by surgical resection. The authors report a rare case of multiple bilateral parotid oncocytomas that presented clinically with two palpable parotid masses. Both CT and MRI scans demonstrated multiple masses in each parotid gland. The tumors exhibited intense uptake and prolonged retention of Tc-99m pertechnetate. The diagnosis was confirmed by fine needle aspiration. Sialoscintigraphy is a simple and noninvasive procedure that can usually separate benign entities like Warthin tumor and oncocytoma of the salivary glands from malignant tumors, and significantly affect the course of treatment.

A 56-yr-old woman was evaluated for removal of a tumor at the base of the skull. A test to determine the risk of carotid artery sacrifice was performed prior to surgery using carotid balloon occlusion of the left internal carotid artery and 99mTc-HMPAO perfusion scintigraphy during the occlusion. An unusual intense focus of increased uptake was seen at the site of the primary tumor in the left cavernous sinus. The tumor, found to be plasmacytoma at surgery, demonstrated only mild washout from 30 min to 2 hr after administration of 99mTc-HMPAO, with a tumor-to-cerebellum ratio of 1.6 and 1.5, respectively, and a tumor-to-contralateral cranial ratio of 2.5 and 2.4, respectively. Intracranial plasmacytoma shows good response to radiation therapy, and the differentiation of this tumor from other neoplasms is pertinent to the mode of treatment and surgical approach. Technetium-99m-HMPAO SPECT imaging may be a useful tool in distinguishing these tumors from other neoplasms at the base of the skull.

Background: Thallium-201 stress imaging is the most often used noninvasive test for detection of coronary artery disease. Its utility in patients with end-stage lung disease has not been defined., Methods: Feasibility, safety, and reliability of thallium 201 perfusion imaging was evaluated in 23 consecutive candidates for lung transplantation. All underwent graded dobutamine thallium 201 single photon emission computed tomography imaging. The perfusion imaging results were correlated with results of coronary angiography, radionuclide angiography, and right heart catheterization., Results: The testing was completed without complications in all patients. No perfusion abnormality was detected in five patients, and none had evidence of coronary artery disease on coronary angiography. In 18 patients with abnormal thallium 201 imaging, coronary artery disease was detected in four patients only, and no angiographic data was available in three patients. Thus, in at least 11 of 23 patients, thallium 201 imaging was falsely positive. There was a trend toward lower left ventricular ejection fraction in patients with abnormal thallium 201 imaging. No correlation was found between thallium 201 results, pulmonary artery and right atrial pressures at rest. Possible noncoronary origin of the perfusion defects include the following (1) presence of sarcoid in the myocardium, (2) left ventricular attenuation by hypertrophied right ventricle, and (3) altered left ventricular anatomy, function, and coronary perfusion as a result of right ventricular pressure overload., Conclusions: Dobutamine thallium 201 stress test can be safely performed in lung transplant candidates. However, its specificity for detection of coronary artery disease is low. Selective use of coronary angiography in patients with multiple risk factors is likely a more cost-effective approach.

The purpose of this study was to determine through noninvasive arm ergometry and radionuclide tomographic imaging the presence of latent coronary heart disease (CHD) in subjects with paraplegia. Assessment of CHD in spinal cord injury, using these methods, has not been addressed previously. Twenty asymptomatic subjects with paraplegia performed arm ergometry exercise stress testing with thallium-201 single photon emission computerized tomography (SPECT) or planar myocardial imaging studies. All subjects had normal resting electrocardiograms (ECG). Only five subjects had ECG evidence of ischemia on exercise testing, whereas 13 subjects, including the five subjects with ECG positive stress tests, had scintigraphic evidence of ischemia. Thus, eight subjects would have been undiagnosed for CHD without thallium-201 SPECT imaging. These individuals had multiple risk factors for CHD and, except for age, were without a statistically significant difference between the groups with positive or negative thallium stress imaging studies. Arm ergometry stress thallium imaging shows a high prevalence of ischemia in subjects with paraplegia.

Unlabelled: The purpose of this study was to evaluate the clinical utility of 99mTc-teboroxime myocardial washout imaging. The differential washout after a single tracer injection has been proposed as an alternative for characterization of the perfusion defects., Methods: Fifty-six patients received 5-min adenosine infusion. The stress dose of 99mTc-teboroxime was injected at 4.5 min and stress imaging with a single-headed SPECT gamma camera was started at 6 min, washout imaging followed immediately. At 20 min, the rest tracer dose was injected at rest and imaging was started at 21.5 min. The reversibility of the perfusion defects on the washout and rest images was compared visually and quantitatively., Results: There was no statistical difference in the number of stress defects that improved on the washout and rest images. The visual interpretation of the perfusion abnormalities was confirmed by quantitative analysis of relative segmental activity., Conclusion: Thus, 99mTc-teboroxime-adenosine washout myocardial perfusion imaging can be safely and quickly accomplished. Detected reversibility of the perfusion defects did not significantly differ from reversibility observed on the rest images.

Myocardial ischemia during routine daily activities was studied in patients with known coronary artery disease with an ambulatory radionuclide probe and recording device (VEST) and routine rest and exercise gated blood pool imaging. Seventeen patients were monitored for 60 minutes while sitting (baseline), standing in place, walking, eating (6 patients), and urinating (4 patients). Eleven of them (64%) failed to show an augmentation of at least 5% in the LVEF on an exercise gated blood pool imaging study (Group I) and 6 (36%) showed a normal response (Group II). Three patients (18%) in Group I experienced angina. Transient left ventricular dysfunction was detected by the VEST during walking, urinating or eating in 80% of the patients in Group I and 33% in Group II (p < 0.05). During walking, mean ejection fraction slightly decreased from 45 +/- 12% to 43 +/- 13% in Group I while the ejection fraction increased from 46 +/- 8% to 51 +/- 12% in Group II (p = 0.04 for the difference in responses). Standing in place and eating did not affect the mean ejection fraction. Urination in 4 patients in Group I caused a significant drop in ejection fraction in 3 patients for a mean change from 51 +/- 9% at rest to 42 +/- 15%. By contrast, none of the patients had angina or diagnostic ECG changes during the monitoring period.(ABSTRACT TRUNCATED AT 250 WORDS)

Forty-two patients with an ejection fraction of 0.20 or less underwent coronary artery bypass grafting from 1986 to 1990 using a method of myocardial protection we term "centigrade cardioplegia," combining single-dose, cold, crystalloid cardioplegia, systemic hypothermia, and local hypothermia. Thirty-day mortality was 4.8% (2/42). Perioperative morbidity included two myocardial infarctions (4.8%) and one stroke (2.4%), which fully resolved. Postoperative left ventricular function improved (left ventricular ejection fraction, 0.157 +/- 0.028 to 0.226 +/- 0.085; p < 0.0002), as did New York Heart Association class (3.4 +/- 0.73 to 1.8 +/- 0.63; p < 0.0001) and Canadian class (3.3 +/- 0.81 to 0.61 +/- 0.92). Survival, 88% at 1 year, declined to 68% at 3 years and 34% at 6 years. This high-risk group had very acceptable short-term results, indicating adequate intraoperative myocardial protection. Four clinical variables were associated with long-term survival: (1) chief complaint of pain only (p = 0.05), (2) history of unstable angina (p = 0.04), (3) Canadian class less than IV (p = 0.05), and (4) New York Heart Association class less than IV (p = 0.05). Reduced survival, although not statistically significant (p = 0.07), was noted for right ventricular ejection fraction of 0.30 or less. These factors may help predict which patients with severe left ventricular dysfunction will benefit from revascularization.

Cardiovascular disease is the leading cause of mortality in those with a spinal cord injury (SCI). As a consequence of changes in body composition and level of activity, individuals with a SCI tend to have a high prevalence of multiple risk factors for coronary artery disease (CAD). In this report, we have demonstrated the usefulness of tomographic thallium-201 myocardial perfusion imaging after intravenous dipyridamole in six clinically asymptomatic subjects with quadriplegia. The average age of the subjects was 47 +/- 2 years, and they had a duration of injury of 15 +/- 2 years. On average, the individuals had five risk factors for CAD. After intravenous administration of dipyridamole and mild upper extremity exercise, the subjects reported no adverse symptoms and had no electrocardiographic evidence suggestive of ischemia. By contrast, three of the six subjects had reversible defects noted on thallium scintigraphy, and one additional subject had a fixed defect that was suggestive of infarction. The remaining two subjects had abnormal scans with fixed defects of the inferioposterior region, which may be ascribed to diaphragmatic attenuation, perhaps a result of partial diaphragmatic paralysis. Thus, dipyridamole thallium myocardial imaging is a safe and effective noninvasive method for the detection of myocardial ischemia or infarction in individuals with quadriplegia who are at increased risk for CAD.

Left ventricular dysfunction during exercise is considered a relatively sensitive marker of ischemia in patients with coronary artery disease. The purpose of this study was to determine whether exercise-induced myocardial dysfunction was more severe in patients with angina than in patients with ischemia without angina. Seventy-seven patients with angiographically documented coronary artery disease and an abnormal left ventricular response to exercise were studied by means of gated blood pool imaging. The arteriographic and functional parameters of 24 patients with angina during exercise testing imaging. The arteriographic and functional parameters of 24 patients with angina during exercise testing were compared with those of 53 patients who were pain free at the time of the test. Both groups were similar with regard to rate of multivessel disease (50% vs 51%, p = NS) and prior myocardial infarction (46% vs 51%, p = NS), as well as age, sex, and history of angina. Mean global ejection fraction remained unchanged (but abnormal) in both groups of patients during exercise. Furthermore, evidence of new regional asynergy during exercise assessed by a five-point scoring system was found to be equally abnormal in the two groups. Results of this study suggest that the severity of exercise-induced global and regional left ventricular dysfunction is independent of the presence of absence of angina during exercise testing.

To assess the clinical and electrophysiologic determinants, treatment and survival of patients with sustained malignant ventricular tachyarrhythmias late after myocardial infarction, a total of 108 patients (mean age 61 +/- 10 years) were studied. Thirty-two patients (Group I) had sustained ventricular tachyarrhythmias 8 to 60 days (mean 13 +/- 9) after acute myocardial infarction. The remaining 76 patients (Group II), who served as a control group, had no sustained ventricular tachyarrhythmias less than or equal to 60 days after infarction. The most significant independent determinants of sustained ventricular tachyarrhythmias late after infarction were the presence of late potentials (chi square = 16.07, p = 0.0001), defined as an abnormal signal-averaged QRS complex in association with an abnormal root-mean-square voltage in the terminal 40 ms of the QRS complex, and an abnormal ejection fraction of less than 40% (chi square = 10.09, p = 0.001). Sustained ventricular tachycardia was induced in 27 (96%) of 28 Group I patients. Among the 32 patients in Group I, antitachycardia therapy included antiarrhythmic drug therapy as the sole preventive measure in 14 (44%); map-guided surgery or coronary artery bypass surgery, or both, in 14 (44%) and the automatic cardioverter-defibrillator in 4 (12%). The arrhythmias were rendered noninducible in 83% of patients after map-guided surgery and in 41% after drug therapy. During a follow-up period of 20 +/- 14 months, five Group I patients (15%) had an arrhythmic event and four (9.3%) had a cardiac-related death. All five patients who had an arrhythmic event were receiving antiarrhythmic drug therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Eight patients in sinus rhythm, with varying degrees of isolated mitral stenosis (mitral valve area 0.6 to 1.3 cm2 and total pulmonary vascular resistance 5.0 to 17.5 U-m2), underwent supine rest and symptom-limited exercise radionuclide ventriculography to determine right ventricular (RV) and left ventricular ejection fraction (EF). Cardiac catheterization with hemodynamic measurements at rest and at peak exercise was performed within 24 hours of radionuclide ventriculography. Four of the 8 patients underwent corrective mitral surgery resulting in normal mean pulmonary artery pressures and total pulmonary vascular resistance at rest. These 4 patients had repeat radionuclide ventriculography at rest and during exercise 1 to 2 months after surgery. Preoperatively, all 8 patients had an abnormal exercise RVEF response (mean change +/- standard deviation [SD], -5.0 +/- 4.5%), coincident with an increase in mean pulmonary artery pressure during exercise (mean change, 15 +/- 5.0 mm Hg). The change in RVEF from rest to exercise, corrected for duration of exercise, correlated with peak exercise mean pulmonary artery pressure (r = -0.71, p = 0.05), as well as total pulmonary vascular resistance at rest (r = -0.82, p = 0.02). Postoperatively, all 4 patients who underwent surgical correction showed a normal RVEF response during exercise (mean change +/- SD, +6.8 +/- 4.0%). Thus, in patients with acquired mitral stenosis and no coronary artery disease (1) loading conditions and not contractility are prime determinants of RV exercise response, and (2) an exercise-induced decrease in RVEF may be a sensitive marker for increased total pulmonary vascular resistance and pulmonary hypertension.

Estimation of left-sided valvular insufficiency has been obtained using the ratio of left- to right-ventricular stroke counts, i.e., the regurgitant index. The present study was designed to evaluate the usefulness of the regurgitant index in identifying patients with isolated right-sided valvular insufficiency. We identified 12 patients with tricuspid or pulmonic regurgitation by at least two of the following criteria: pulsatile liver, positive Carvallo's sign, and pulsatile jugular-venous distension. In 9 of the 12 patients, the right-sided insufficiency was confirmed by catheterization or contrast echocardiography and flow-directed pulsed-echo Doppler. The regurgitant index in patients with right-sided insufficiency was 0.59 +/- 0.23. This was significantly different from patients with left-sided insufficiency (3.09 +/- 0.8; P less than 0.001) and from control subjects (1.49 +/- 0.32; P less than 0.001). In 11 of the 12 patients with right-sided regurgitant lesions, the regurgitant index was less than 1.0. The hepatic expansion fraction, a possible correlate of an expansile liver, has previously been found to be both sensitive and specific for the detection of patients with right-sided regurgitation. We calculated the hepatic expansion fraction in 6 patients with tricuspid regurgitation (including 3 with pulsatile livers) and 5 controls using the method of Handler et al.. In the present study, the hepatic expansion fraction in tricuspid-insufficiency patients was 4.3% as compared to 4.1% in normals (P = NS). In summary, this study suggests that the regurgitant index may be a sensitive tool for the diagnosis of right-sided regurgitant lesions, while the hepatic expansion fraction does not appear to be useful for identifying tricuspid insufficiency.

Timing abnormalities of myocardial contractility may occur as inter- or intraventricular asynchrony. Gated blood pool scintigraphy was performed on 21 patients with a normal ejection fraction and the following electrocardiograms: six normal, six with left bundle branch block, four with right bundle branch block and five with right ventricular pacemaker rhythm. A phase and amplitude of the first harmonic of the Fourier transform was obtained for each pixel, and left and right ventricles were trisected. A mean vector phase for each region was obtained by vector summation. Regional and global values were analyzed within each group and compared with normal values. The phase differences between the entire left and right ventricles (mean +/- standard deviation) were: 9 +/- 3 in the normal patients, 38 +/- 8 (p less than 0.01) in patients with left bundle branch block, -6 +/- 7 (p less than 0.05) in patients with right bundle branch block and 15 +/- 9 (difference not significant) in patients with pacemaker rhythm. The phase differences between left ventricular posterolateral and septal regions were -4 +/- 2 in the normal patients, 10 +/- 5 (p less than 0.01) in patients with left bundle branch block, -7 +/- 10 (p less than 0.05) in patients with right bundle branch block and 10 +/- 5 (p less than 0.01) in patients with pacemaker rhythm. Within the right ventricle, phase differences between the apical and septal segments were 14 +/- 9 in the normal patients, 14 +/- 10 (NS) in patients with left bundle branch block, -2 +/- 3 (p less than 0.01) in patients with right bundle branch block and -22 +/- 18 (p less than 0.01) in patients with pacemaker rhythm. Interventricular phase differences were greatest in patients with left bundle branch block and absent or reversed in right bundle branch block.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

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.

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.

Blood-pool subtraction has been proposed to enhance 111In-labeled platelet imaging of intracardiac thrombi. We tested the accuracy of labeled platelet imaging, with and without blood-pool subtraction, in ten subjects with cardiac thrombi of varying age, eight with endocarditis being treated with antimicrobial therapy and ten normal controls. Imaging was performed early after labeled platelet injection (24 hr or less) and late (48 hr or more). Blood-pool subtraction was carried out. All images were graded subjectively by four experienced, "blinded" readers. Detection accuracy was measured by the sensitivity at three fixed levels of specificity estimated from receiver operator characteristic curve analysis and tested by three-way analysis of variance. Detection accuracy was generally improved on delayed images. Blood-pool subtraction did not improve accuracy. Although blood-pool subtraction increased detection sensitivity, this was offset by decreased specificity. For this population studied, blood-pool subtraction did not improve subjective detection of abnormal platelet deposition by 111In platelet imaging.

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.

The effect of labeling media on the kinetics of[111In]platelets was evaluated by performing a paired crossover study in eight normal human subjects using tropolone and oxine methods. Platelets were labeled in autologous plasma with [111In]tropolone (In-tr) and in ACD-saline with [111In]oxine (In-ox) and reinjected. Starting at 1 hr, ten blood samples were obtained over an 8-day period. The in vivo platelet recovery was higher at 1 hr and throughout the 8 days of study with In-tr and the gamma camera images showed less uptake in liver and spleen than with In-ox. When platelet life-span (PLS) was estimated using all ten samples, only linear regression showed that the platelet life-span was longer with In-tr (10.7 +/- 1.5) than with In-ox (9.5 +/- 0.8). When the PLS was estimated excluding the 1-hr sample point, the life-span of platelets was significantly longer with In-tr than with In-ox based on three out of four models of curve fitting. These results demonstrate that platelets labeled with In-tr in plasma are preserved better in circulation and have equal or longer life-span than platelets labeled with In-ox in ACD-saline.

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.

In order to estimate the precision and accuracy of parameters derived from segmental multiharmonic Fourier analysis of gated blood-pool images, a Monte Carlo computer noise simulation was tested on five sample regional time-activity curves. The first three Fourier harmonics were retained and the precision and accuracy of parameters of ventricular function were calculated, varying the ejection fraction, segment size, and framing rate. Precision improved with higher ejection fraction, higher counts per frame, or higher framing rate. There was no change in precision as the framing rate changed at fixed total counts. Accuracy changed little with changing framing rate. Thus, for segmental analysis there is no advantage to using a higher framing rate. Regions five or more pixels in size are recommended for reliable results. This study provides useful information for the optimization of acquisition and processing conditions for regional gated blood-pool analysis.

Differences in vertical orientation of the left ventricle within the chest cavity cannot be corrected by gamma camera positioning. The effect of variations in vertical angulation on the appearance of the diagnostically important left anterior oblique (LAO) view has not been previously evaluated. In the current study, a computer simulation of a normal left ventricle was created and "imaged," varying only the degree of vertical rotation. The effect of six vertical positions on the LAO image was assessed visually and with horizontal and circumferential profile analysis. Results indicate a homogenous distribution of counts in the horizontal views. With increasing verticality, there are fewer counts in the valve plane, while the inferoapex initially increases in count density, and then progressively decreases. Quantification revealed count variations of up to 37% in the valve plane and 45% in the inferoapex due entirely to differences in vertical orientation of the left ventricular simulation. A survey of 167 patients who underwent routine stress thallium imaging showed a vertical angulation that varied from 7 degrees to 64 degrees (mean = 37 degrees) as determined from the anterior view. Clinical images were similar in appearance to computer generated images after correction for anterior view foreshortening. The present study suggests that the accuracy of current quantitative thallium methods to detect coronary artery disease might be enhanced by the use of a revised set of normal standards corrected for vertical orientation of the left ventricle.

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.

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)

A prospective study was undertaken of the prognostic significance of quantitative signal-averaged electrocardiographic (ECG) variables relative to clinical variables, site of myocardial infarction, left ventricular ejection fraction and characteristics of ventricular premature beats in 115 patients (mean age 62 +/- 12 years) studied 10 +/- 6 days after myocardial infarction. Signal-averaged variables included the root mean square voltage of the terminal 40 ms, the duration of the filtered signal-averaged QRS complex and low amplitude signals less than 40 microV determined at 25 and 40 Hz high pass filtering in all patients. Of the 115 patients, 51 (44%) had an abnormal signal-averaged ECG (one or more abnormal signal-averaged variables), 51 (44%) at 25 Hz and 48 (42%) at 40 Hz high pass filtering. A higher proportion of patients with an inferior wall infarction had an abnormal signal-averaged ECG as compared with patients with anterior wall infarction (58% versus 31%). Over a 14 +/- 8 month follow-up period 16 patients (14%) had an arrhythmic event. An abnormal signal-averaged ECG at 40 Hz high pass filtering had a higher sensitivity (81% versus 75%) and specificity (65% versus 61%) than at 25 Hz high pass filtering. The predictive value of the signal-averaged ECG was superior to that of the ejection fraction (40% versus 20%) in anterior wall myocardial infarction, whereas in patients with inferior wall infarction, the predictive values of the two tests were equivalent. The prognostic power of 27 clinical and noninvasive variables was determined with the Cox proportional hazards regression model.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

This study of biventricular segmental timing sequences compared patterns of the first-harmonic phase with those of multiharmonic Fourier-analysis-derived parameters to determine their suitability for the classification of patients using an automatic pattern recognition scheme. The study involved nine patients with normal ECGs, six with left bundle branch block, 4 with right bundle branch block, and 6 with right-ventricular pacemakers; all patients had normal left-ventricular function. The segmental sequence described by the time of end systole was similar to that described by the first-harmonic phase, with a lower correlation using the time of maximum filling rate, and a rather poor correlation of the time of maximum ejection rate with the other parameters. Thus, despite theoretical difficulties, timing patterns described by phase best agreed with those of the time of end systole. Intersegmental timing differences were used as criteria for discriminating between groups by means of a sequential logic tree. Using either phase, time of end systole or time of maximum ejection rate, all patients were correctly classified into the four ECG categories. More intersegmental timing differences were useful as criteria for phase (57) than for the time of end systole (45) or the time of maximum ejection rate (30). The first-harmonic phase was more efficient than the time of end systole for separating patient groups. Sequential biventricular timing disorders can be objectively classified using either first-harmonic or multiharmonic Fourier analysis, and their patterns can be automatically recognized and used for classification.

Although both time domain and frequency domain analysis of signal-averaged electrocardiograms (ECGs) may distinguish patients with and without sustained ventricular tachycardia, it remains unclear which method is superior. Both methods were assessed in 55 subjects comprising 26 patients with sustained ventricular tachycardia (Group I), 18 control patients with organic heart disease but without sustained ventricular tachycardia (Group II) and 11 normal volunteers (Group III). Time domain analysis was performed with high pass filtering of 25, 40 and 80 Hz and low pass filtering of 250 Hz. Frequency domain analysis was performed on the terminal 40 ms of the QRS complex, either alone or with 216 or 150 ms of the ST segment. Absolute summed energies of discrete frequency bands and band energy ratios were calculated. The effectiveness of discrimination between Groups I and II was evaluated in terms of group means, sensitivity, specificity and an information content index based on receiver operating characteristic curve analysis. Group I showed a uniform decrease in amplitude across all frequencies derived from the terminal 40 ms of the QRS complex (p less than 0.005). This was abolished by the inclusion of ST segment data in frequency domain analysis. No frequency band was unique for Group I. At a specificity of 78%, the best time domain sensitivity was 85%, and the best frequency domain sensitivity was 77%. The best time domain information content index was 0.156, the best index for frequency domain analysis was 0.077 using absolute band areas. It is concluded that patients with sustained ventricular tachycardia have decreased energy content across all frequencies in the terminal 40 ms of the QRS complex. Frequency domain analysis was not an improvement over time domain analysis in differentiating patients with ventricular tachycardia from those without.

Patients with coronary artery disease may have reversible abnormalities on a thallium myocardial perfusion study without simultaneous ischemic changes on the exercise electrocardiogram, but the mechanisms responsible for this disparity have not been fully elucidated. A group of 37 patients with angiographically demonstrated coronary artery disease and abnormal thallium perfusion imaging were divided into two groups on the basis of their exercise electrocardiographic ST segment response. Thirteen patients (Group A) had no significant electrocardiographic changes with exercise, while 24 patients (Group B) had ST changes consistent with ischemia during the test. There were no significant differences in clinical or angiographic characteristics between the two groups. Stress test results showed a similar mean duration of exercise in the two groups (6.2 +/- 1.8 versus 6.7 +/- 2.5 min, p = NS), but the patients in Group A achieved a significantly lower mean maximal heart rate (117 +/- 26 versus 132 +/- 21 beats/min, p less than 0.05) and mean maximal double product (19,650 +/- 5116 versus 22,650 +/- 4871, p less than 0.05). There was no consistent pattern of thallium perfusion abnormality noted in Group A to suggest that a particular region of electrically silent myocardium was responsible for ischemia in the absence of electrocardiographic changes. These results suggest that exercise thallium-electrocardiogram discordance is mediated by the level of myocardial workload achieved. An abnormal perfusion scan accompanying an exercise electrocardiogram which does not demonstrate any ischemic ST change may occur when there is sufficient increase in myocardial oxygen demand to result in differential augmentation of myocardial blood flow, but insufficient imbalance of supply and demand to result in signs of ischemia on the surface electrocardiogram.