William L. Ashburn

Temporal response of left ventricular performance to mitral valve surgery.

We separated MR patients into two subgroups. In 12 subjects (group 1) with preoperative EDD = 5.94 0.42 cm, ESD = 3.55 ± 0.43 cm, and EF = 0.70 ± 0.05, EF fell slightly by 6 months after surgery to 0.59 ± 0.10 (p < 0.01), but remained within the normal range. Concomitantly, left ventricular hypertrophy regressed, as CSA was 24.2 6.5 cm2 before and 18.6 ± 2.4 cm2 after surgery (p < 0.01). contrast, in four subjects (group 2) with preoperative EDD = 8.07 ± 0.35 cm, ESD = 5.69 ± 0.70 cm, and EF = 0.57 ± 0.05, left ventricular function progressively deteriorated after surgery, with EF falling 0.26 ± 0.06 (p < 0.01). In the latter group left ventricular hypertrophy did not regress (CSA = 31.5 ± 4.5 cm2 before and 31.9 ± 3.4 cm2 after surgery, NS). Techniques for myocardial preservation during mitral valve surgery did not differ between the MR and MS groups. In group 2 MR subjects, there was no evidence of intraoperative myocardial infarction.

Myocardial imaging with thallium-201: A multicenter study in patients with angina pectoris or acute myocardial infarction

A multicenter study of rest and exercise thallium-201 myocardial imaging in 190 patients from five centers was performed. Exercise images were obtained after graded treadmill or bicycle stress with use of five different gamma camera models and were interpreted by the originating investigator without knowledge of other clinical data. Of 42 patients with less than 50 percent coronary stenosis, 4 (10 percent) had a resting image defect, 1 (2 percent) a new exercise defect and 5 (12 percent) either a resting or an exercise image defect, or both. Of 148 patients with coronary stenosis of 50 percent or greater, 64, (45 percent) had an image defect in the study at rest, 90 (61 percent) had new or increased defects after exercise, and 115 (78 percent) had resting or exercise defects, or both. New exercise image defects were more common than exercise S-T depression (90 of 148 [61 percent] versus 62 of 148[42 percent]; P less than 0.01). In a second group of 111 patients with acute myocardial infarction studied at three centers, 90 patients (81 percent) had image defects compared with 71 (64 percent) two had new electrocardiographic Q waves (P less than 0.01). Smaller infractions, as assessed with serum enzyme values, and diaphragmatic infarctions were less commonly detected than larger or anterior infarctions. These findings suggest that myocardial imaging complements the electrocardiographic identification of acute myocardial infarction of exericse-induced myocardial ischemia.

Left ventricular volumes by gated equilibrium radionuclide angiography: a new method.

To compare radionuclide end-diastolic (EDV) and end-systolic (ESV) volumes with angiographic volume, we studied 52 patients with equilibrium radionuclide angiography using 99mTc-human serum albumin within 48 hours of contrast angiography. Each RR interval was divided into 20–28 equally timed frames and a time-activity curve generated. End-diastolic counts were taken at the early peak of the curve and end-systolic counts at its nadir. Counts were divided by the total number of processed heart beats and normalized for: 1) dose per body surface area; 2) plasma volume; and 3) counts/ml of plasma. A cardiac phantom was developed and serial volumes were studied using a normalization factor. Radionuclide values were expressed as dimensionless units and compared with either biplane angiographic volumes (in the patient studies) or known phantom volumes. Good correlations were obtained with methods 1 and 2 in 35 patients (r > 0.84), but the best correlation was obtained in 17 patients when normalization for counts/ml of plasma was used (r = 0.98; y = 0.255 x −0.121). The standard error of the estimate (SEE) was ± 11.5 ml for EDV and ± 7.3 ml for ESV. The phantom study also showed an excellent correlation (r = 0.99), with a SEE of ± 6.5 ml. We conclude that a radionuclide method independent of geometric assumptions can be used to estimate left ventricular volume in man.

Nontraumatic determination of left ventricular ejection fraction by radionuclide angiocardiography.

Previous reports have suggested that left ventricular ejection fraction can be assessed by recording the passage of peripherally administered radioactive bolus through the heart. The accuracy and validity of this technique were examined in 20 patients undergoing diagnostic cardiac catheterization. 99m-Tc-human serum albumin was injected via a central venous catheter into the superior vena cava and precordial activity recorded with a gamma scintillation camera interfaced to a small digital computer. A computer program was designed to generate time-activity curves from the left ventricular blood pool and to calculate left ventricular ejection fractions from the cyclic fluctuations of the left ventricular time-activity curve which correspond to left ventricular volume changes during each cardiac cycle. The results correlated well with those obtained by biplane cineangiocardiography (r equals 0.94) and indicated that the technique should allow accurate and reproducible determination of left ventricular ejection fraction. The findings, however, demonstrated that the time-activity curve must be generated from a region-of-interest which fits the left ventricular blood pool precisely and must be corrected for contributions arising from noncardiac background structures. This nontraumatic and potentially noninvasive technique appears particularly useful for serial evaluation of the acutely ill patient and for follow-up studies in nonhospitalized patients.

Right ventricular ejection fraction in patients with acute anterior and inferior myocardial infarction assessed by radionuclide angiography.

SUMMARYWe measured right and left ventricular ejection fraction (EF) from high frequency time-activity curves obtained during the initial passage of an intravenous bolus of 99mTc (Sn) pyrophosphate. In 22 normal controls right ventricular EF averaged 0.52 ± 0.04 (SD). In 24 acute anterior or lateral infarction patients right ventricular EF was normal (0.56 ± 0.10), while left ventricular EF was reduced (0.45 ± 0.10, P < 0.001 vs controls). In 19 acute inferior infarction patients left ventricular EF also was depressed (0.51 ± 0.09, P < 0.001 vs controls). Among 7 of 19 inferior infarc- tion patients with right ventricular infarction by scintigraphy, right ventricular EF was reduced (0.39 ± 0.05; P < 0.001 vs normals; P < 0.01 vs inferior infarction patients without right ventricular involvement). In the latter group right ventricular EF averaged 0.51 ± 0.10 (NS vs normals). We conclude 1) a single injection of 19mTc (Sn) pyrophosphate can identify right and left ventricular dysfunction and infarct location in acute myocardial infarction, 2) right ventricular EF is well-preserved except when inferior infarction involves the right ventricle.

Serial measurements of left ventricular ejection fraction by radionuclide angiography early and late after myocardial infarction

The left ventricular ejection fraction was determined serially with radioisotope angiography in 63 patients with acute myocardial infarction. After the peripheral injection of a bolus of technetium-99m, precordial radioactivity was recorded with a gamma scintillation camera and the ejection fraction calculated from the high frequency left ventricular time-activity curve. Since this technique requires no assumptions with respect to left ventricular geometry, it is particularly useful in patients with segmental left ventricular dysfunction. Serial measurements during the first 5 days after hospital admission were made in 50 patients, 30 of whom were studied during the subsequent 2 to 39 months (mean 19.9 months). Late follow-up serial studies were also performed in an additional 13 patients who had only one measurement of the left ventricular ejection fraction during the early postinfarction period. Early after infarction, the left ventricular ejection fraction was normal (more than 0.52) in only 15 of the 63 patients, and averaged 0.52 +/- 0.05 (standard deviation) in the 27 patients with an uncomplicated infarct. The ejection fraction was reduced in 24 patients with mild to moderate left ventricular failure (0.40 +/- 0.05, P less than 0.0001) and in the 12 patients with overt pulmonary edema (0.33 +/- 0.07, P less than 0.0001). In 35 patients the ejection fraction correlated with the mean pulmonary arterial wedge pressure (r = 0.72). In 15 patients with normal left ventricular wall motion by heart motion videotracking, the ejection fraction was significantly higher (0.53 +/- 0.08) than in the 26 patients with regional left ventricular dysfunction (0.41 +/- 0.10, P less than 0.0001). During the early postinfarction period, the left ventricular ejection fraction improved in 55 percent of patients and remained unchanged or decreased in 45 percent. A further increase in the ejection fraction was noted in 61 percent of patients during the late follow-up period. Patients with an initially low or decreasing ejection fraction had a significantly greater incidence of early mortality and left ventricular dysfunction (P less than 0.02) than those whose ejection fraction was normal or improved to normal early after infarction. These data indicate that the ejection fraction is a sensitive indicator of left ventricular function after acute myocardial infarction and that serial measurements are helpful in predicting early mortality and morbidity.

A Randomized Trial of Exercise Training in Patients With Coronary Heart Disease

In order to determine whether or not regular exercise could alter myocardial perfusion or function, we randomized 146 male volunteers with stable coronary heart disease to either a supervised exercise program (n = 72) or to a usual care program (n = 74). Subjects underwent exercise tests initially and one year later. Significant differences between the two groups included improved aerobic capacity, thallium ischemia scores, and ventricular function in the exercise intervention group. It was not possible to classify the conditions of patients as to the likelihood of improvement or deterioration. This study demonstrated changes in myocardial perfusion and function in a select group of middle-aged men with coronary heart disease who underwent a medically appropriate exercise program lasting one year, but these changes were relatively modest.

Gallium-67 for Localization of Septic Lesions

Abstract Gallium-67 citrate was administered intravenously to 12 septic patients. Gamma camera scintiphotos and rectilinear scans showed focal accumulation of the gallium in 11 of the patients. In ...

Assessment of right ventricular function at rest and during exercise in patients with coronary heart disease: A new approach using equilibrium radionuclide angiography

Abstract To evaluate a new method of calculating right ventricular ejection fraction by equilibrium radionuclide angiography and to assess its response during supine bicycle exercise, 20 normal persons and 50 patients with angiographically documented coronary artery disease were studied. Each subject underwent a resting equilibrium and first pass right ventricular study as well as symptom-limited graded bicycle exercise while supine. The correlation between the two methods in all 70 cases was good (r = 0.81). Inter- and intraobserver variability was small (3.9 ejection fraction units or less) and serial reproducibility (two studies performed 2 weeks apart) was also good (4 ejection fraction units or less). There was no difference in the right ventricular ejection fraction at rest when normal subjects and patients with coronary disease were compared (0.49 ± 0.10 versus 0.46 ± 0.08). Ejection fraction increased with exercise in normal subjects (0.49 ± 0.10 to 0.64 ± 0.12, p

Relationship of QRS amplitude changes during exercise to left ventricular function and volumes and the diagnosis of coronary artery disease.

Preliminary studies have suggested that QRS-amplitude changes due to exercise-induced alterations in ventricular volume and function can improve the diagnostic value of the exercise test. To evaluate this, electrocardiographic data and equilibrium radionuclide angiographic images were recorded simultaneously in 18 normal subjects and 60 coronary artery disease patients at rest and during supine bicycle exercise. In 24 of the 60 coronary artery disease patients, left ventricular volumes were also calculated. The measured QRS amplitudes were the R waves in V5, X, Y and Z, the Q wave in Z and the sum of amplitudes of R waves in X and Y and the Q wave in Z (2iR). The mean left ventricular ejection fraction increased significantly from rest to peak exercise in the normal subjects; however, the mean left ventricular ejection fraction and mean volumes did not change significantly in the coronary patients. There was no significant difference in the mean QRS-amplitude changes during exercise between the coronary artery disease patients and the normal subjects in any of the measured leads. The sensitivity and specificity of exercise-induced QRS-amplitude changes for coronary disease were lower than ST-segment changes. For ST-segment changes, the sensitivity was 57% and specificity was 100%; the best sensitivity and specificity for QRS amplitude occurred in RZ, 48% and 67%, respectively. When ejection fraction was related to 2R at rest and peak exercise for both normal subjects and coronary patients the correlations were fair (0.50, 0.51 respectively); however, the correlation between the magnitude of 2R and ejection fraction change from rest to peak exercise was poor and did not improve with any other measured QRS amplitudes or by separating normal subjects from coronary patients with and without previous myocardial infarction. There were also poor correlations between end-diastolic and endsystolic volumes to QRS amplitudes at rest, peak exercise and their magnitude of change from rest to peak exercise. Thus, R-wave amplitude changes during exercise testing have little diagnostic value and are not related to exercise-induced changes in left ventricular function or volumes.