Thallium-201 myocardial perfusion scintigraphy to evaluate patients after coronary bypass surgery.

To determine the utility of thallium-201 stress scintigraphy in assessing the results of coronary bypass surgery, chest pain, stress electrocardiograms and scintigrams were evaluated in 27 patients postoperatively. These findings were compared with coronary angiographic data in which a significant postoperative lesion was defined as 75 percent or more stenosis in a graft, its distal vessel or in an ungrafted native vessel. As an indicator of postoperative coronary lesions, chest pain lacked sensitivity (60 percent) and was nonspecific (20 percent). The stress electrocardiogram had poor sensitivity (60 percent) and good specificity (86 percent) but was not helpful in six patients who had equivocal or suboptimal tests. The scintigram had good sensitivity (77 percent) and was highly specific for the diagnosis of coronary stenosis. It was significantly more specific than chest pain (P less than 0.01), gave excellent localizing information and added to the accuracy of both conclusive and inconclusive stress tests. In nine patients with preoperative stress scintigrams, comparison of pre- and postoperative studies reflected the éffects of bypass surgery on coronary perfusion. Scintigraphy is a useful technique for the noninvasive evaluation of the patient after coronary bypass surgery, and postoperative scintigraphy alone is of great value in documenting surgical results.     

Late prognostic value of scintigraphic parameters of acute myocardial infarction size in complicated myocardial infarction without heart failure

Perfusion scintigraphy with thallium-201, infarct scintigraphy with technetium-99m pyrophosphate (TcPYP), and equilibrium blood pool scintigraphy were performed during the initial hospitalization for acute myocardial infarction (MI) in 25 patients without evidence of heart failure who presented with advanced electrocardiographic rhythm and conduction disturbances requiring treatment. Scintigraphic findings during short-term hospitalization were related to the late clinical follow-up performed an average of 14 months later, where patients were grouped as asymptomatic, 8 patients; symptomatic, 9 patients; and deceased, 8 patients. Quantitation of perfusion abnormalities, TcPYP image abnormalities, and left ventricular ejection fraction (EF) revealed that the deceased group had significantly larger TcPYP abnormalities (36 +/- 20 cm2), absolute perfusion abnormalities (32 +/- 16 cm2), and perfusion abnormalities expressed as a percentage of the projected left ventricular area (42 +/- 8%) than the asymptomatic group (13 +/- 8 cm2, 14 +/- 6 cm2, and 20 +/- 9%; p less than 0.05, p greater than 0.05, and p less than 0.01, respectively). The percent perfusion abnormality was significantly larger in the deceased group (42 +/- 8%, p less than 0.01) than in either the symptomatic group (35 +/- 13%, p less than 0.01) or the asymptomatic group (20 +/- 9%), and this parameter in the symptomatic group also differed from that in the asymptomatic group (p less than 0.01). The study indicates that patients with rhythm and conduction disturbances and without congestive heart failure during acute MI may follow an uncomplicated or a complicated late clinical course. Early scintigraphic measurements of MI and perfusion correlate well with this outcome; however, EF could not differentiate among prognostic subgroups.     

Value of noninvasive assessment of patients with atypical chest pain and suspected coronary spasm using ergonovine infusion and thallium-201 scintigraphy

Twenty-six patients with known benign coronary anatomic characteristics and atypical chest pain syndromes were evaluated for the possibility of coronary spasm. Incremental intravenous ergonovine maleate infusions were administered, and thallium-201 scintigraphy was performed at the peak dosage and during recovery in the coronary care unit. With ergonovine therapy, 4 patients (16%) had chest pain associated with electrocardiographic (ECG) or scintigraphic changes. Nine patients (35%) had chest pain without associated ECG or scintigraphic changes, and 13 patients did not have chest pain in response to ergonovine administration, although 2 (8%) had ergonovine-induced scintigraphic defects. All 4 patients with ergonovine-induced chest pain and associated ECG or scintigraphic abnormalities had resolution or reduction of chest pain after medical treatment. However, 7 of the 9 patients with ergonovine-induced chest pain in the absence of ECG or scintigraphic abnormalities continued to have symptoms despite medical treatment a mean of 18 months later. In this limited study of a select group, bedside ergonovine provocation appeared safe. Many patients had chest pain, but few showed ECG or scintigraphic evidence of ischemia. Perfusion scintigraphy appears to have potential complementary value for the identification of an ischemic cardiac cause of atypical chest pain and provides a rationale for appropriate therapy.     

The significance of nitroglycerin-induced changes in ventricular function after acute myocardial infarction

The potential of nitroglycerin for improving global and regional ventricular function after acute myocardial infarction and predicting serial change in ventricular function at the time of hospital discharge was investigated. Equilibrium multiple gated blood pool scintigrams were performed at rest before and after sublingual administration of nitroglycerin in 18 patients an average of 36 hours after infarction and again at discharge. Global right and left ventricular function and regional left ventricular function of infarct and noninfarct zones were determined scintigraphically.In the early study nitroglycerin increased both mean (± standard deviation) left ventricular ejection fraction (0.51 ± 0.15 to 0.55 ± 0.15; p < 0.02) and mean right ventricular ejection fraction (0.42 ± 0.14 to 0.47 ± 0.13; p < 0.05). Left ventricular ejection fraction significantly increased in 5 of the 18 patients. It Increased late in five of the six patients who exhibited an increase early after nitroglycerin but in only 2 of the 12 patients who did not exhibit an early increase (p < 0.06). Regional ejection fraction in the infarct zone increased late in 7 of the 12 patients who exhibited an early increase after nitroglycerin and in none of the 6 who did not exhibit an early increase (p < 0.05). Both right and left ventricular global ejection fraction and regional ejection fraction showed little late responsiveness to nitroglycerin.Early after infarction, sublingual nitroglycerin improved left, right and regional ejection fraction at the infarct site in some patients. These nitroglycerin-induced changes predicted those patients whose global ventricular function and regional left ventricular function at the infarct site improved late.     

An accurate means of detecting and characterizing abnormal patterns of ventricular activation by phase image analysis

The ability of scintigraphic phase image analysis to characterize patterns of abnormal ventricular activation was investigated. The pattern of phase distribution and sequential phase changes over both right and left ventricular regions of interest were evaluated in 16 patients with normal electrical activation and wall motion and compared with those in 8 patients with an artificial pacemaker and 4 patients with sinus rhythm with the Wolff-Parkinson-White syndrome and delta waves. Normally, the site of earliest phase angle was seen at the base of the interventricular septum, with sequential change affecting the body of the septum and the cardiac apex and then spreading laterally to involve the body of both ventricles. The site of earliest phase angle was located at the apex of the right ventricle in seven patients with a right ventricular endocardial pacemaker and on the lateral left ventricular wall in one patient with a left ventricular epicardial pacemaker. In each case the site corresponded exactly to the position of the pacing electrode as seen on posteroanterior and left lateral chest X-ray films, and sequential phase changes spread from the initial focus to affect both ventricles. In each of the patients with the Wolff-Parkinson-White syndrome, the site of earliest ventricular phase angle was located, and it corresponded exactly to the site of the bypass tract as determined by endocardial mapping. In this way, four bypass pathways, two posterior left paraseptal, one left lateral and one right lateral, were correctly localized scintigraphically. On the basis of the sequence of mechanical contraction, phase image analysis provides an accurate noninvasive method of detecting abnormal foci of ventricular activation.     

Noninvasive diagnosis of a false left ventricular aneurysm with radioisotope gated cardiac blood pool imaging: Differentiation from true aneurysm

Unlike the true left ventricular aneurysm, false aneurysms have recently been shown to be subject to late rupture. Rarely diagnosed before surgery or autopsy, the false aneurysm has never been identified by noninvasive techniques. We report the first such noninvasive diagnosis employing radioisotope gated cardiac blood pool imaging. Due to the unique and possibly life-threatening clinical course and potential for surgical cure of false left ventricular aneurysm, early noninvasive diagnosis by imaging techniques may be critical. The methods shown here are generally applicable, becoming widely available and may help in evaluation of false left ventricular aneurysm as a cause of sudden death.     

Interaction of "supplementary" scintigraphic indicators of ischemia and stress electrocardiography in the diagnosis of multivessel coronary disease

Lung uptake, ventricular cavitary dilation and basal myocardial uptake represent abnormalities that have been associated with myocardial ischemia on stress thallium-201 images, but that are supplementary to the conventional assessment of perfusion distribution. These "supplementary" indicators of ischemia were related to the coronary distribution of perfusion abnormalities, the results of electrocardiographic stress testing and to the findings on coronary angiography in 73 patients. Forty patients had multivessel coronary disease; 19 of these had three vessel disease. Perfusion abnormalities were seen in 39 of these 40 patients but were indicative of multivessel coronary disease in only 28 and of three vessel disease in only 6. However, supplementary indicators were present in 33 of 40 patients with multivessel disease and in 15 of 19 with three vessel disease. Furthermore, they were seen in 16 of 22 patients with multivessel disease in whom conventional perfusion abnormalities underestimated the extent of disease, but in only 4 of 12 patients in whom the extent of disease was overestimated. The presence of either perfusion abnormalities in a multivessel distribution or supplementary indicators identified 38 (95%) of 40 patients with multivessel disease. A markedly positive electrocardiographic treadmill test was a less sensitive indicator of multivessel disease, appearing in only 15 of 40 patients. However, it was present in only 4 of 33 patients without multivessel coronary disease and was more specific for that diagnosis than were supplementary scintigraphic indicators (88 versus 67%, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Phase image characterization of ventricular contraction in left and right bundle branch block

The phase image is a computer-derived functional image, based on the analysis of the time versus radioactivity curve in each pixel location of the multiple gated blood pool scintigram. Within the ventricular regions of interest, the phase angle is roughly equivalent to the time of onset of counts reduction or to the time of onset of ventricular contraction and is expressed in degrees from 0 to 360 °. A gray scale-coded image of such a regional phase angle, the phase image, can be looked on as a map of sequential contraction. This method was applied in 33 patients without severe contraction abnormality including 16 patients with normal conduction, 9 with right bundle branch block and 8 with left bundle branch block. In patients with normal conduction the pattern of phase angle distribution, representing the pattern of ventricular contraction, was homogeneous and symmetric in both the left and right ventricles. Analysis in this normal group indicated a slight but significant difference between the mean (± standard deviation) phase angle of the left ventricle (8.5 ± 11.8 °) and that of the right ventricle (13.6 ± 12.9 °, p = 0.01). There was a slight, but nonsignificant difference between mean intrapatient left and right ventricular phase angle onset (1.9 ± 6.5 °).The mean phase angle of the right ventricle in patients with right bundle branch block (27.6 ± 14.2 °) and of the left ventricle in those with left bundle branch block (21.9 ± 14.0 °) was delayed compared with that in patients with normal conduction (p < 0.05 for both). The mean intrapatient difference between left and right ventricular mean phase angles in patients with normal conduction (?5.2 ± 6.8 °) was significantly different from that in patients with right (?21.8 ± 10.3 °, p < 0.001) or left (21.8 ± 6.8 °, p < 0.001) bundle branch block. The mean intrapatient difference between onset of left and right ventricular phase angles was also significantly different from normal in patients with right (?10.6 ± 7.5 °, p < 0.005) or left (18.7 ± 8.3 °, p = 0.01) bundle branch block.Although phase imaging is not without artifactual error, this study demonstrates that the phase image can characterize familiar conduction abnormalities. It presents the potential for application as a general noninvasive tool in the investigation of the timing and sequence of ventricular contraction in patients with normal or abnormal ventricular activation.     

Mechanism of protection from atherosclerosis by verapamil in the cholesterol-fed rabbit

Seventy-two rabbits were separated into groups to receive no drug, subcutaneous verapamil, metoprolol, hydralazine, metoprolol and hydralazine, or oral verapamil in 1 of 3 doses daily for 10 weeks. They also received a high-cholesterol diet and had serum triglyceride, cholesterol, and verapamil levels measured twice during the study. Blood pressure (BP), heart rate and weight were measured every 10 days. Approximately 60% of the rabbits given verapamil had detectable levels of the drug in their serum. This group had significantly less severe atherosclerosis in their aortas at the time they were killed, even though they had significantly higher cholesterol levels than the other groups. This group also did not have different BP than the other groups (except for the subcutaneous verapamil group). Thus, protection from atherosclerosis by verapamil in the cholesterol-fed rabbit is not the result of lowering of BP.