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The value of right ventricular thallium-201 analysis in detecting proximal right coronary artery stenosis in exercise myocardial scintigraphy was analyzed in 52 patients, 27 with and 25 without proximal right coronary artery stenosis. For the detection of proximal right coronary artery stenosis, the sensitivity and specificity of thallium scintigraphic analysis were 59 and 88% for a right ventricular abnormality, 67 and 68% for a left ventricular inferior wall abnormality, and 93 and 56% for an abnormality of either. When both right and left ventricular thallium images were abnormal, all 9 patients had proximal right coronary artery stenoses, and when both were normal, 26 of 28 patients had a normal proximal right coronary artery. The sensitivity and specificity of blood pool scintigraphic variables during exercise (right ventricular ejection fraction and left ventricular inferior wall motion) were not significantly different for detection of proximal right coronary artery stenosis. Thus, the additional analysis of the right ventricle on thallium-201 stress scintigrams can improve the detection of proximal right coronary artery stenosis. When both right ventricular and left ventricular thallium scintigrams are abnormal (or normal), the ability to predict the presence (or absence) of proximal right coronary artery stenosis is very high.

Nonsurgical recanalization of the occluded coronary artery has been performed in patients with evolving myocardial infarction since the late 1970s by intracoronary administration of thrombolytic agents at the ostium of the occluded artery or directly to the site of occlusion. The authors review the basic concepts underlying intracoronary thrombolysis, the method applied at their institution and the clinical results. Reperfusion of totally occluded arteries or termination of the ischemic state in subtotally occluded arteries was achieved in 71 (87.7%) of 81 patients. Reocclusion occurred in four patients, in three of these at a time when anticoagulation became temporarily ineffective, emphasizing the need for uninterrupted anticoagulation with a partial thromboplastin time longer than 80 seconds. Thallium scintigraphic studies before and after reperfusion showed a decrease in defect, indicating myocardial salvage, in the successful cases but not in failures or untreated control subjects. A decrease in thallium-201 defect was followed by improvement of regional wall motion and usually also left ventricular ejection fraction. Three of the patients with an unsuccessful result and one patient with a successful result died. Bypass surgery was performed electively in 18 patients because of multiple vessel involvement. Intracoronary thrombolysis appears to be a relatively safe and promising procedure. A large controlled study will be needed for definitive assessment of its role in the management of acute myocardial infarction.

Upright and supine multiple gated cardiac blood pool scintigraphy was performed at rest and during maximum exercise in 37 patients, 15 with normal coronary arteriograms, 12 with coronary artery disease (CAD) without myocardial infarction (MI), and 10 with CAD and previous MI. Heart rate and systolic blood pressure were similar during upright and supine exercise in normal patients, but were significantly lower during supine exercise in both CAD groups. Left ventricular (LV) ejection fraction (EF), right ventricular (RV) EF, and LV segmental wall motion were similar in the upright and supine positions at rest or during maximum exercise within each group and showed high concordance of exercise responses. Although LV end-diastolic volume increased in all three groups during upright exercise and in both CAD groups when exercised supine, it did not change during supine exercise in patients without CAD. The fall of LV end-systolic volume in normals was greater during supine exercise than during upright exercise. LV end-systolic volume rose in the CAD patients in both positions. Therefore, although LVEF, RVEF, and LV segmental wall motion responses are similar in the upright and supine positions, LV end-systolic and LV end-diastolic volume changes are not. For detecting and evaluating CAD, the two different positions of exercise appear to have similar diagnostic content.

Despite high sensitivity and specificity for overall detection of coronary artery disease (CAD), planar stress-redistribution thallium-201 (Tl-201) scintigraphy remains suboptimal in localizing disease, because of overlap of myocardial segments. Single photon emission computerized tomography (SPECT), by providing three-dimensional representation of myocardial Tl-201, offers promise for improved localization of CAD. In 50 consecutive patients (22 normal and 28 with CAD), who underwent SPECT stress-redistribution Tl-201 imaging, we systemically developed visual interpretive criteria for perfusion abnormality on SPECT. For overall detection of disease, the best criterion for abnormality was greater than or equal to 8 sectors of moderately decreased Tl-201 uptake. With this criterion, the true positive and true negative rates for overall detection of disease were 96% and 91%, respectively. The best criterion for significant defect in the anterior or posterior coronary circulation was greater than or equal to 3 sectors of moderately decreased Tl-201 uptake. With this criterion, the true positive and true negative rates for anterior circulation disease were 71% and 100%, respectively. With respect to posterior circulation disease, the true positive and true negative rates were 100% and 50%, respectively. Regarding identification of dual circulation disease, the true positive and true negative rates were 71% and 82%, respectively.

Unlabelled: While exercise-induced segmental left ventricular wall motion abnormalities are well described, the phenomenon of improvement in certain asynergic segments during exercise in some patients remains a curiosity. To assess this unexpected finding, results were analyzed in 85 patients with wall motion abnormalities at rest who underwent two view (45 degrees left anterior oblique and anterior) exercise radionuclide ventriculography and exercise thallium-201 myocardial perfusion imaging. Wall motion was scored with a 5 point system (from 3 [normal] to - 1 [dyskinesia]); normalization or increase of 2 or more points with exercise signified improvement. Forty-eight patients (56%) had no change or further deterioration of wall motion at peak exercise, 15 (18%) showed both improvement of wall motion and deterioration and 22 (26%) showed only improvement of wall motion. Wall motion improvement during exercise was found in 57 (20%) of 279 segments with asynergy at rest. Of these 57 segments improving with exercise, 45 (79%) showed mild and 12 (21%) showed severe asynergy at rest. Only seven segments (12%) were associated with pathologic Q waves. Thallium-201 perfusion was normal in 44 segments (77%) while only 6 segments (11%) had reversible and only 7 (12%) had nonreversible thallium-201 defects., In Conclusion: 1) wall motion that is abnormal at rest can sometimes improve with exercise; 2) this phenomenon generally occurs in zones without a Q wave or nonreversible thallium-201 defect. Hence, segments with abnormal wall motion at rest that show improvement with exercise appear to represent viable nonischemic segments.

Since coronary artery disease often first manifests as sudden death or myocardial infarction before symptoms develop, the early detection of disease may identify patients at risk for an acute event. Stress redistribution thallium-201 scintigraphy provides a useful, noninvasive method for assessing the presence of CAD as well as for evaluating the extent of disease. The principles and methods of thallium scintigraphy are described herein in addition to its clinical application. The availability of noninvasive thallium-201 scintigraphy has added to the physician's ability to accurately diagnose CAD, to objectively evaluate the effects of coronary artery bypass surgery, and to assess patients with acute myocardial infarction.

To investigate the myocardial perfusion correlates of precordial ST segment depression during acute inferior myocardial infarction, a rest thallium-201 scintigram and a closely timed 12 lead electrocardiogram were obtained within 6 hours of the onset of infarction in 44 patients admitted with their first acute inferior myocardial infarction. Thirty-six patients demonstrated precordial ST segment depression (group 1) and eight did not (group 2). A perfusion defect involving the inferior wall was present in all 44 patients. Additional perfusion defects of the adjacent posterolateral wall (n = 20), the ventricular septum (n = 9) or both (n = 6) were present in 35 of 36 patients from group 1 compared with only 1 of 8 patients from group 2 (p less than 0.001). There was no significant difference in the frequency of multivessel coronary artery disease or disease of the left anterior descending artery between group 1 and group 2 or between patients with and those without a thallium-201 perfusion defect involving the ventricular septum. Thus, precordial ST segment depression during an acute inferior myocardial infarction is associated with thallium-201 scintigraphic evidence of more extensive involvement of the adjacent posterolateral or inferoseptal myocardial segments, which probably reflects the extent and pattern of distribution of the artery of infarction, rather than the presence of coexistent multivessel coronary artery disease or disease of the left anterior descending artery.

On exercise thallium-201 scintigraphy, it has been noted that the size of the left ventricle is sometimes larger on the immediate poststress image than on the 4 hour redistribution image; this phenomenon has been termed transient ischemic dilation of the left ventricle. The angiographic correlates of this finding were assessed in 89 consecutive patients who underwent both stress-redistribution thallium-201 scintigraphy and coronary arteriography. A transient dilation ratio was determined by dividing the computer-derived left ventricular area of the immediate postexercise anterior image by the area of the 4 hour redistribution image. In patients with a normal coronary arteriogram or nonsignificant coronary stenoses (less than 50%), the transient dilation ratio was 1.02 +/- 0.05 and, therefore, an abnormal transient dilation ratio was defined as greater than 1.12 (mean + 2SD). The transient dilation ratio was insignificantly elevated in patients with noncritical coronary artery disease (50 to 89% stenosis) (1.05 +/- 0.05) and in patients with critical stenosis (greater than or equal to 90%) of only one coronary artery (1.05 +/- 0.05). In contrast, in patients with critical stenoses in two or three vessels, the transient dilation ratio was significantly elevated (1.12 +/- 0.08 and 1.17 +/- 0.09, respectively; p less than 0.05 compared with all other patient groups). An abnormal transient dilation ratio had a sensitivity of 60% and a specificity of 95% for identifying patients with multivessel critical stenosis and was more specific (p less than 0.05) than were other known markers of severe and extensive coronary artery disease, such as the presence of multiple perfusion defects or washout abnormalities, or both.(ABSTRACT TRUNCATED AT 250 WORDS)

To compare stress/rest technetium 99m methoxy isobutyl isonitrile (Tc-MIBI) with stress redistribution thallium 201(T1-201) myocardial perfusion imaging, 36 patients were studied by single photon emission computerized tomography (SPECT) and planar methods. For SPECT, overall sensitivities for identification of patients with coronary artery disease were 93% (14/15) by Tc-MIBI and 80% (12/15) by TI-201 (p = NS). For planar methods, overall sensitivities were 73% (11/15) by both TI-201 and Tc-MIBI. Overall specificity was 75% (3/4 patients with normal coronary arteries) for both tracers with SPECT and Tc-MIBI by planar imaging and was 50% for planar TI-201 (p = NS). The normalcy rates for overall identification of coronary artery disease were determined in 17 patients with a low likelihood of disease. For SPECT, normalcy rates were 100% by Tc-MIBI and 77% by TI-201 (p = NS). For planar, they were 94% by Tc-MIBI and 88% by TI-201 (p = NS). Vessel sensitivities in the 35 stenosed coronary arteries (greater than or equal to 50% stenosis) for SPECT were 87% by Tc-MIBI and 77% by TI-201 (p = NS). For planar, the vessel sensitivities were 60% by Tc-MIBI and 54% by TI-201 (p = NS). For both tracers, the SPECT vessel sensitivities were significantly higher (p less than 0.005) than planar vessel sensitivities. The vessel specificities in 22 coronary vessels with less than 50% stenosis were 86% by SPECT Tc-MIBI and TI-201, 80% by planar Tc-MIBI and 73% by planar TI-201 (p = NS, SPECT vs planar, Tc-MIBI vs TI-201). Regarding myocardial segmental agreement, for the presence of stress defects the agreement was 91% for the 720 SPECT segments and 95% for the 540 planar segments. For severity of stress defects based on semiquantitative visual scoring, the exact agreement was 87% for SPECT and 80% for planar. For the pattern of reversibility in myocardial segments with stress defects, the agreement was 97% for SPECT and 91% for planar. This study demonstrated that Tc-MIBI and TI-201 correlate well on both planar and SPECT images with respect to the identification of patients with coronary artery disease, identification of disease in individual coronary arteries, the presence and severity of perfusion defects, and the assessment of defect reversibility. Furthermore, SPECT Tc-MIBI was shown to be superior to planar Tc-MIBI for the identification of individual diseased vessels.

In 5 of 69 patients (7%) undergoing intracoronary or intravenous streptokinase treatment, the ST-segment elevations in leads V1 to V5 were caused by occlusion of the right rather than the left anterior descending coronary artery and by myocardial infarction (MI) of the right ventricular (RV) wall rather than the anterior left ventricular (LV) wall or the ventricular septum. RV involvement was documented by technetium pyrophosphate uptake, hypokinesia, dilatation and depressed RV ejection fraction. The left anterior descending artery was patent and the anterior LV wall had normal thallium-201 uptake, no technetium uptake and normal wall motion. ST-segment elevation was highest in lead V1 or V2 and decreased toward lead V5; in patients with anterior LV MI, the ST-segment elevations are usually lowest in lead V1 and increase toward the V5 lead. In contrast to anterior LV infarcts, the R waves in leads V1 to V5 did not decrease and Q waves did not evolve with progression of the MI. The ST-segment elevations in leads V1 to V5 in our patients were associated with small or absent ST-segment elevations in leads, II, III and aVF, suggesting that in other cases of RV infarction, the appearance of ST-segment elevations in leads V1 to V5 is blocked by the dominant electrical forces of the LV inferior MI. This suggestion was confirmed in a canine model. Recognition of the presence of RV infarction may be therapeutically important.

An abnormal increase in pulmonary thallium activity may be visualized on post-stress thallium images in patients with coronary artery disease. Because this increased pulmonary thallium activity usually disappears by the time of redistribution imaging, this study was designed to assess whether measurement of the degree of pulmonary thallium washout between stress and redistribution might improve the detection of increased pulmonary thallium activity in patients with coronary artery disease. Quantitative analysis revealed abnormal (that is, greater than 2 standard deviations of normal values) pulmonary thallium washouts in 59 (64%) of 92 patients with coronary artery disease, but in only 2 (25%) of 8 subjects with angiographically normal arteries (p less than 0.06). By comparison, the visual analysis of pulmonary thallium washout and use of initial pulmonary to myocardial thallium ratio were significantly (p less than 0.05) less sensitive in detecting abnormality in patients with coronary artery disease. Abnormal pulmonary thallium washout was related to both the anatomic extent and functional severity of disease: it occurred with greatest frequency in patients with multivessel disease and in those with exercise-induced left ventricular dysfunction (p less than 0.005). When added to the quantitative analysis of myocardial scintigraphy, the analysis of pulmonary thallium washout increased the detection of coronary artery disease from 84 to 93% (p less than 0.05), but the sample size was too small to assess specificity. Thus, the analysis of pulmonary thallium washout is a useful diagnostic variable because it: 1) provides an objective measurement of abnormal pulmonary thallium activity and is more sensitive than other methods; 2) correlates with both the extent of coronary artery disease and the degree of exercise-induced left ventricular dysfunction, and 3) improves the sensitivity of quantitative myocardial thallium scintigraphy to detect the presence of coronary artery disease.