Radionuclear measurement of peripheral hemodynamics in selection of vasodilators for treatment of heart failure.

In order to select the optimal vasodilator for the treatment of patients with congestive heart failure (CHF), the acute effects of three vasodilators (isosorbide dinitrate (ISDN) 5 mg, nifedipine 10 mg, and prazosin 1 mg) on peripheral capacitance and resistance vessels (CV and RV) were evaluated by a newly devised radionuclear technique (Study 1). Thirty-six patients with chronic CHF were divided into Group A (ejection fraction (EF) greater than or equal to 35%, n = 20, mean EF: 47.2 +/- 6.5%) and B (EF less than 35%, n = 16, mean EF: 24.8 +/- 7.1%). ISDN produced the strongest CV dilatation (25% in both groups). Nifedipine reduced RV tone in Groups A and B (14% and 27%, respectively), and CV tone in Group A (6%). Prazosin had the most prominent effects on both vessels in Group B. From these results, it appeared: (a) ISDN is indicated for the cases with increased CV tone, (b) nifedipine is suitable for those with increased RV tone, (c) in cases of increased tone in both vessels, nifedipine (when EF greater than or equal to 35%) or prazosin (when EF less than 35%) is optimal. To evaluate the validity of this assignment, 49 subjects with CHF were divided into Group 1 (n = 16, increased CV tone), Group 2 (n = 17, increased RV tone), and Group 3 (n = 16, increased CV and RV tone) in Study 2. In Group 1, the changes of all indexes were not significantly different between the subjects treated with optimal drug based on the assignment (subgroup P) and those with a non-optimal drug (subgroup N) after 2 wk of therapy. In Group 2, however, improvements of RV tone, EF, and exercise duration in subgroup P were greater than those in subgroup N (31 versus 10%, 21 versus 0%, 41 versus 14%, respectively). In Group 3, the results were the same as in Group 2 (34 versus 19%, 24 versus 8%, 26 versus 9%). These findings suggested that the selection of the optimal vasodilator based on peripheral hemodynamic evaluation with a newly devised radionuclear technique permits more effective treatment of chronic CHF.

[Comparison of two-dimensional echocardiography with 201T1-single photon emission computed tomography for evaluating the myocardial infarct zone].

The reliability of measuring the myocardial infarct zone by two-dimensional echocardiography (2 DE) was compared with that by regional myocardial blood flow as evaluated by single photon emission computed tomography (SPECT) in 47 patients with old myocardial infarction, with ventricular aneurysm (An group; n = 15), and without ventricular aneurysm (Non-An group; n = 32). Short-axis images of the left ventricle at the level of the mitral valve, the papillary muscles, and the apex were obtained both by 2DE and SPECT. The left ventricular wall was divided into 36 segments in 2DE and 40 segments in SPECT with reference points at the posterior end of the right side of the interventricular septum. The segments in which the radial shortening on 2DE and the 201Tl uptake index on SPECT were below one standard deviation from the means of 10 normal subjects were defined as those with abnormal wall motion and hypoperfused areas, respectively. The relationships between these findings were studied. The extent of apical movement was measured by left ventricular cineangiography in each case, and was compared between the An and Non-An groups. 1. Wall motion abnormalities on 2DE and hypoperfusion on SPECT showed a correspondence of 81% in the An group and 78% in the Non-An group at the level of the mitral valve, and 78% in the An group and 76% in the Non-An group at the papillary muscle level. However, a better correspondence was observed in the An group (84%) as compared to the Non-An group (64%) at the level of the apex. 2. Apical movement assessed by cineangiography showed more extensive changes in the Non-An group than in the An group (2.3 +/- 0.9 mm vs 4.1 +/- 1.7 mm in the RAO view, 2.4 +/- 1.9 mm vs 5.3 +/- 2.1 mm in the LAO view). From these observations, it was suspected that the cause of disparity between radial shortening and the 201Tl uptake index at the level of the apex is related to the cardiac movement of the apex toward the base during systole. 3. Since wall motion abnormalities demonstrated by radial shortening (2DE) and hypoperfusion indicated by the 201Tl uptake index (SPECT) generally corresponded well, 2DE was thought to be a useful method for evaluating myocardial infarct zone.

[Infarct size determined by emission computed tomography using 99mTc-PYP: effect of coronary thrombolysis].

Emission computed tomography with 99mTc-PYP was used to estimate infarct size in 38 patients with documented acute myocardial infarction. In the present study, the effect of thrombolysis with Urokinase on infarct size and on left ventricular function was assessed. Fourteen patients with acute myocardial infarction who underwent intracoronary thrombolysis within six hours after the onset of symptoms, and 24 patients who underwent conventional therapy were the subjects of this study. Infarct size was measured by drawing a region of interest around the myocardial pyrophosphate uptake for each tomographic slice. The boundary was then defined as 65% of the maximal count within the region of interest as determined by phantom volume studies. The total number of voxels was obtained by adding those in all slices and multiplying the sum by the voxel volume (0.205 ml per one voxel) to determine the infarct volume. Measurement of the 99mTc-PYP uptake on the tomographic image revealed an average infarct size of 100.1 +/- 36.0 ml (ranged 45 to 198). The calculated infarct volume correlated significantly with sigma CPK (p less than 0.01) and with left ventricular ejection fraction (p less than 0.01), but not with the peak CPK. In patients with acute inferior myocardial infarction, the mean infarct volume was 78.4 +/- 29.1 ml in the coronary thrombolysis group, and 105.1 +/- 33.7 ml in the conventional bypass graft treatment group (p less than 0.05). We concluded that successful intracoronary thrombolysis may reduce infarct size. ECT imaging with 99mTc-PYP to determine infarct size may be clinically applicable in patients with acute myocardial infarction.

[Right ventricular ejection and regional wall motion evaluated by cardiac blood pool emission computed tomography].

Calculating right ventricular (RV) ejection fraction (EF) is difficult because of geometrical problems such as irregular trabeculations, a separate infundibulum, and variations in the right ventricular shape. We performed 99mTc ECG-(dual)gated cardiac blood pool emission computed tomography (ECT) in 10 patients with ischemic heart disease, three patients with dilated cardiomyopathy (DCM), and eight normal subjects as controls, and RVEF and % shortening of the RV were calculated to evaluate right ventricular function. Methods were as follows: 1) RVEF: The region of interest (ROI) of the RV was determined on reconstructed short-axial images, and then the RV counts in the ROI were summed from the apical slice to the RA-RV boundary slice. (Formula: see text) 2) % shortening of the RV: At the RV mid-portion, the contour from the short-axial image was obtained using the threshold method; the end-diastolic contour was superimposed on the end-systolic contour, and then shortenings in the RV free wall and septum respectively, were calculated. To evaluate reliability of RVEF obtained by this method, left ventricular ejection fraction (LVEF) calculated using the same method was compared with results obtained by the previously validated method: There were significant correlations with contrast cineangiography (r = 0.69) and the conventional multigated method (r = 0.90), respectively. Cases with decreased RVEF showed a variety of right ventricular abnormal findings, including positive uptake on 99mTc-PYP scintigraphy, occlusion of the right coronary artery, RV dilatation on echocardiography. The mean RV free wall shortening in the decreased RVEF group was lower than that of the normal group (p less than 0.01), whereas there was no significant difference in the decreased LVEF group.(ABSTRACT TRUNCATED AT 250 WORDS)

[Left ventricular asynergy detected by cardiac blood pool emission computed tomography using the subtraction method].

To evaluate left ventricular regional wall motion, ECG dual-gated cardiac blood pool ECT was performed for 25 patients with ischemic heart disease, including 19 cases of myocardial infarction, five cases of angina pectoris, and one case of post A-C bypass surgery. There were six normal controls. Following SPECT obtained using 32 views (180 degrees), the vertical and horizontal long axes were reconstructed from transaxial images. Then, regional wall motion was evaluated from subtraction images; (end-diastolic)-(end-systolic) and (end-systolic)-(end-diastolic) images. SPECT images were compared with left ventriculography (LVG); vertical long-axial ECT images with segments 1-5 of LVG by the AHA classification, and horizontal ECT long-axial images with segments 6 and 7 of LVG, respectively. The subtraction images from ECG dual-gated cardiac blood pool ECT corresponded with left ventriculography in 79.4% of 175 segments in 25 patients with ischemic heart disease (sensitivity 92.6%, specificity 68.0%, and accuracy 79.4%). When wall motion was classified as normal, hypokinesis, akinesis, and aneurysmal, good agreement was observed between the two methods in 68% of these segments. The locations of asynergy as obtained by this method were closely in accord with those of perfusion defects by Tl-201 myocardial SPECT in 74.4% of segments. Left ventricular aneurysms were detected using subtraction image; (end-systolic)-(end-diastolic). We conclude that this subtraction method is useful for evaluating left ventricular asynergy.

[Scintigraphic detection of thrombi using indium-111-labeled autologous platelets].

Intracardiac and arterial thrombi were examined by scintigraphy using In-111-oxine labeled autologous platelets. In 22 cases of myocardial infarction including six with ventricular aneurysms, four had positive findings of thrombi on imaging and detected also by echocardiography. All four had ventricular aneurysms. The so-called "moya-moya" echoes (fuzzy echoes) were demonstrated in two of these four cases. We encountered two cases with positive findings on imaging in 13 with mitral valve disease. These two had systemic embolic episodes after scintigraphic examination. "Moya-moya" echoes were detected in the left atrial cavity in four with negative findings on imaging. Positive images were obtained in two of three with acute arterial occlusive disease, and in both cases platelet deposition was observed in the proximal site of obstruction. Though thrombectomy was performed for one of these two cases, no thrombus was detected at the site of platelet deposition. After one month, re-examination revealed only negative findings in all sites in both these patients. In the six cases of aortic aneurysm, three had platelet deposition within their aneurysms, and surgery was performed for these positive cases, but one of them had no thrombus. Positive images were obtained in only one of seven patients with chronic arterial occlusive disease. Coagulation tests and platelet studies were investigated for patients with positive or negative platelet scans. Only the data of the thrombo-test showed a significant difference (97 +/- 9% vs 23 +/- 7%, p less than 0.001). Three cases of positive imaging became negative after anticoagulant therapy. We tried ECT for eight cases 24 hours after injection of In-111-oxine labeled platelets. Three cases showed clear images of thrombi, while the planar images could not detect them at an early stage. Therefore, we propose that ECT can be a useful technique for diagnosing intracardiac thrombi in early stage.