Clinical significance of the right ventricular free wall appearance on stress Tl-201 myocardial images in ischemic heart disease.
In order to evaluate the clinical significance of thallium (Tl)-201 myocardial imaging for diagnosing the right ventricular (RV) ischemia, we studied the relationship of right ventricular free wall (RVFW) appearance on myocardial images to coronary arteriographic findings. Patients were divided into 3 groups as follows: 1) normal control (NC) group (19 cases) without angiographically documented coronary artery disease; 2) non-RCA group (18 cases) with significant coronary artery lesion restricted to the left coronary artery (LCA); and 3) RCA group (36 cases) with significant right coronary artery (RCA) stenosis regardless of underlying LCA disease. After the patients had exercised up to 80-85% of the predicted maximal heart rate, immediate and 3-4 hour delayed myocardial images were obtained. As for presence or absence of the RV ischemia on images, the RVFW appearance in 30 degrees and 60 degrees left anterior oblique (LAO) views were assessed carefully. On the immediate images, all patients except one in the NC group and all except 3 in the non-RCA group demonstrated 'continuous visualization' of the RVFW in both views. In the RCA group, 6 showed 'non-visualization' and 11 'defective visualization' of the RVFW in 30 degrees LAO view. In 60 degrees LAO view, 6 presented 'non-visualization' and other 6 'defective visualization' of the RVFW. On the delayed images, although none of the patients in the groups NC and non-RCA demonstrated redistribution phenomenon of the RVFW, 4 patients in the RCA group showed redistribution of Tl-201 into the RVFW. Non- and defective visualization of the RVFW on the immediate images were related to the proximally located RCA lesion, previous history of inferior myocardial infarction and high grade RCA stenosis. Collateral vessels seemed to protect the RVFW against the development of exercise induced ischemia and affect the occurrence of redistribution of Tl-201 into the RVFW. In conclusion, stress Tl-201 myocardial imaging enables us to estimate the myocardial blood flow of the RV and is a useful non-invasive method in the evaluation of RV ischemia.
D000328:Adult; D000368:Aged; D003097:Collateral Circulation; D017023:Coronary Angiography; D003326:Coronary Circulation; D003327:Coronary Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006352:Heart Ventricles; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications; D011868:Radioisotopes; D011877:Radionuclide Imaging; D013793:Thallium
D011868:Radioisotopes; D013793:Thallium