Daniel R. Biello

Left ventricular diastolic filling and its association with age

Thirty normal subjects, aged 22 to 80 years, were studied by radionuclide ventriculography to determine the age dependence of cardiac ventricular diastolic function and to evaluate the association of other factors with ventricular diastolic performance. A strong negative correlation was found between peak diastolic filling rate and age (r = -0.82, p less than 0.0001). Partial correlation analysis was used to factor out the strong age dependence and yielded additional significant correlations of peak filling rate with heart rate (r = 0.48, p less than 0.01) and time to peak filling rate (r = -0.48, p less than 0.01). Time to peak filling rate is also correlated with heart rate but not definitely with age. Analysis by multiple linear regression yields an equation predicting peak filling rate from age and heart rate. Thus, the rate of rapid diastolic filling declines markedly with age in normal subjects. The association of peak filling rate with age and with other factors indicates the need for careful consideration of these factors in the interpretation of scintigraphic findings in patients with heart disease.

Interpretation of Indeterminate Lung Scintigrams

Lung scintigrams and pulmonary angiograms of 111 patients with suspected pulmonary embolism who had matching perfusion defects and radiographic abnormalities (infiltrate, atelectasis, or effusion) were reviewed. In 14 patients perfusion defects were substantially smaller than the corresponding radiographic opacity; only 1 (7%) had pulmonary embolism. In 77 the opacities and perfusion defects were of similar size; the abnormality was due to embolism in 20 (26%). In 18 patients perfusion defects were substantially larger than the radiographic opacities and were not associated with matching ventilation abnormalities; of these, 16 (89%) had pulmonary embolism. Evaluation of the relative size of perfusion defects and radiographic abnormalities occurring in the same region improves the ability of lung scintigrams to predict pulmonary emboli.

Computed tomography and radionuclide imaging of the liver: a comparative evaluation.

The authors retrospectively analyzed the results of radionuclide imaging (RI) and computed tomography (CT) of the liver in 174 patients. RI correctly identified 90% of patients with focal hepatic lesions while CT identified 85%. CT was capable of differentiating tumor, abscess/hematoma, and cyst while RI was more sensitive in the detection of hepatocellular disease. CT distinguished regenerating nodules from other focal lesions. Radionuclide imaging remains the preferred initial screening examination in patients with suspected focal liver disease, while CT is the examination of choice to distinguish obstructive from nonobstructive jaundice.

The roles of gallium-67 scintigraphy, ultrasonography, and computed tomography in the detection of abdominal abscesses

The evaluation of patients with suspected abdominal abscesses begins with a history and careful physical examination. Gallium-67 (67Ga) scintigraphy, ultrasonography (US), and computed tomography (CT) are utilized only after other routine investigations have failed to localize the abscess. All three modalities are reliable for the detection of abdominal abscesses. The decision regarding which of these three diagnostic tests to use in a particular patient rests upon clinical considerations. If the patient has acute localizing signs and symptoms, 67Ga should not be used initially. In this type of patient, rapid diagnosis is best provided by either US or CT. Further radiologic investigation may be terminated if the CT or US findings are characteristic of an abscess. A 67Ga scan should be performed in a patient with acute localizing signs and symptoms if the initial CT or US is negative. In a patient with nonlocalizing signs and symptoms, 67Ga imaging should be employed as the first procedure since the entire body is easily surveyed. If the 67Ga images are abnormal, then CT or US should be utilized for further lesion characterization. This diagnostic approach will optimize the rapidity of patient evaluation and will minimize diagnostic errors.

Laboratory and initial clinical studies of nifedipine, a calcium antagonist for improved myocardial preservation.

This report summarizes five years of laboratory investigations and the initial six-month clinical experience with a calcium antagonist, nifedipine, added to a cold hyperkalcmic cardio-plcgic solution for enhancement of myocardial protection. Regional ischemia was created in 112 dogs and global ischemia in 98 dogs, under normothermic and two hypothermic states. Control solutions, two clinical cardioplegic solutions, and nifedipine solutions were compared. Infusion of nifedipine during regional ischemia and repcrfusion intervals resulted in a two-to-thrccfold reduction in injury volume and maintenance of normal left ventricular function in contrast to infusion of nitroprusside. Nifedipine solutions (0.2 μ/ml) provided superior preservation of left ventricular function in comparison to the two cardioplegic solutions after one hour of global ischemia at 37 C and two hours at 18 C. In a clinical trial of nifedipine in cold potassium cardioplegia, 38 high risk patients with poor ventricular function have been treated; 22 of which were intensively studied serially with radionuclide ventriculography and pyrophosphate scans, myocardial isoenzyme determinations, 24 hour EKG recordings and intra-and postoperative hemodynamic studies. Of the 35 patients admitted to the intensive care unit (ICU), 33 have survived. Stroke work and cardiac indices return promptly to near normal levels after operation. The time-isoenzyme activity curves are low and radionuclide determined ejection fractions show no change for the study group. Death from acute postischemic cardiac failure did not occur in treated patients and the usage of intra-aortic balloon pump (IABP) has decreased threefold in comparison with 40 similar high risk patients treated concurrently with cardioplegic solution alone. It is concluded that nifedipine is a potent adjunct to cold hyper-kalemic cardioplegic solution in high risk patients.

Chest pain after nontransmural infarction: the absence of remediable coronary vasospasm.

To assess the contribution of coronary vasospasm to chest pain in patients with nontransmural myocardial infarction, we performed a controlled trial of prophylactic antivasospastic therapy. Fifty patients with nontransmural infarction received either nifedipine or placebo in a double-blind randomized trial. Chest pain occurred in 52% of treated patients (38 episodes on 35 days) compared to 48% of control patients (42 episodes on 33 days). Concurrent therapy was comparable in the two groups. Recurrent infarction occurred in 12% and was comparable between groups. Ejection fraction was similar and was unchanged throughout the study in both groups. Logistic regression failed to identify predictors for recurrent chest discomfort. These data indicate that potent antivasospastic therapy does not reduce the incidence of recurrent chest pain or infarction. Thus, remediable coronary vasospasm is not likely to be a major cause of post infarction ischemia in patients with nontransmural infarction.

Gated cardiac blood pool imaging and thallium-201 myocardial scintigraphy for detection of remote myocardial infarction

Abstract The primary goal of this study was to assess the frequency of persistent regional wall motion abnormalities and myocardial perfusion defects detectable late after myocardial infarction with radionuclide ventriculography and thallium-201 imaging, respectively. The study was performed prospectively in 32 patients in whom infarct size was estimated enzymatically at the time of the acute episode and in 10 patients without infarction. Thallium-201 imaging and radionuclide ventriculography were performed with the patient at rest an average of 11 months after infarction (range 6 to 20 months) and analyzed independently by two observers who were unaware of results of other clinical and laboratory data. Perfusion defects were detected in 94 percent (30 of 32) by observer I and in 91 percent (29 of 32) by observer II. Wall motion abnormalities were detected in 78 percent (25 of 32) and 75 percent (24 of 32) by observers I and II, respectively, but in 10 of the patients with an infarct size less than 20 creatine kinase-gram-equivalents (CK-g-eq), wall motion abnormalities were found in only 50 and 40 percent, respectively, by these observers (p

Impaired Left Ventricular Function during Exercise in Coronary Artery Disease and Exertional Hypotension

To characterize the hemodynamic abnormalities responsible for exertional hypotension coronary artery disease, we studied 11 patients with exertional hypotension during supine cycle ergometer exercise, defined as greater than 10 mm Hg decrease in systolic blood pressure during exercise, and 11 patients without exertional hypotension (controls). Patients were similar with respect to age, left ventricular ejection fraction at rest, and the intensity of exercise relative to maximal treadmill exercise capacity. Peak exercise ejection fraction, determined by radionuclide ventriculography, was significantly lower in patients with, than in those without exertional hypotension (50 +/- 3 vs. 56 +/- 3%; p less than 0.025). Ejection fraction and stroke volume decreased with exercise in patients with exertional hypotension but not in the controls even though changes in end-diastolic volume and mean blood pressure were similar in both groups. Peak exercise systolic blood pressure and rate pressure product were significantly lower in the patients with exertional hypotension than those without. The exercise-induced regional left ventricular contraction abnormalities were more prominent, extensive and frequent in patients with exertional hypotension than controls. Impairment of left ventricular contractile function was further evident by an abnormal end-systolic volume-systolic blood pressure relation in patients with exertional hypotension. These patients attained a much smaller increase in systolic blood pressure compared with controls despite no statistically significant differences in end-systolic volume response to exercise. These findings suggest that exertional hypotension in patients with ischemic heart disease is associated with exercise-induced left ventricular systolic dysfunction secondary to extensive myocardial ischemia.

Symmetrical perfusion defects without pulmonary embolism

We report two patients with ventilation-perfusion (V-P) images that demonstrate large symmetric perfusion defects with normal chest radiographs and ventilation images who did not have pulmonary embolism (PE) by angiography. This experience suggests that patients with symmetrical V-P mismatches should not be assumed to have PE. The need for pulmonary angiography in such patients should be carefully considered.

The (F)utility of the thallium-201 quantitative lung/myocardial ratio in the detection of coronary artery disease

Exercise-induced increases in pulmonary uptake of thallium-201 (201Tl) have been associated with exercise-induced myocardial dysfunction. To evaluate this phenomenon more replicably, a quantitative semi-automated computer program was used to generate, from anterior exercise and delayed views, lung-myocardial ratios (LMR) of201Tl uptake in 78 patients [40 normal, 38 with coronary artery disease (CAD)]. Patients with CAD had a significantly higher mean exercise lung myocardial ratio (EXLMR) than normals (30.8 vs. 27.3;P < 0.003). In patients with adequate exercise (≥85% of an age-adjusted maximal heart rate), the EXLMRs of CAD patients were significantly higher than those of normals (29.7 vs. 25.5;P=0.003). However, this difference between CAD and normal patients was not apparent in a patient subgroup with submaximal exercise levels (< 85% of an age-adjusted maximal heart rate). In both normal and CAD patients, EXLMR decreased with increasing exercise levels (r=-0.555;P=0.007). In patients with201Tl scans lacking visually defined perfusion defects (visually normal), an elevated LMR detected 60% of CAD cases with 81% specificity. A considerably elevated EXLMR in patients achieving adequate exercise should suggest the presence of CAD, even if there are no visually apparent cardiac perfusion defects. With submaximal exercise, however, the EXLMR is not a useful discriminator between CAD patients and normals.