Analysis of papillary muscle images on planar thallium-201 myocardial scintigrams in various heart diseases

Abstract

²⁰¹Tl myocardial imaging can, noninvasively, visualize the various cardiac structures; such as the left ventricle, right ventricle and, occasionally, the atrium. We have noted that certain patients exhibit a prominent appearance of the papillary muscle on a scintigram. Thus, we analyzed ²⁰¹Tl myocardial scintigrams for evidence of activity which corresponded to the anterolateral (A-PM) and posteromedial (P-PM) papillary muscles.

Twenty normal subjects, 81 patients with ischemic heart disease (IHD), 11 with hypertrophic cardiomyopathy (HCM) and 13 with dilated cardiomyopathy (DCM) were examined. Patients with DCM had rest imaging only, while the remaining ones performed exercise studies. The prevalence of a positive A-PM image was not high (9%–23%) and there was no significant difference among groups. The P-PM was seen in only 15% of the normal group and in 18% of the HCM group, while the prevalence was high in the IHD (34.6%) and DCM (53.8%) groups. In the IHD, the positive images of the P-PM were largely from the subgroup with single vessel left anterior descending (LAD) coronary artery disease (78.9%). However, even in the presence of a defect in the left ventricular wall supplied by the LAD coronary artery, the patients with multi-vessel coronary artery disease did not tend to disclose the P-PM on the scinti-gram (30.8%). Thus, we conclude that positive P-PM imaging on a planar ²⁰¹Tl myocardial scintigram is frequently observed under some cardiac states and seems to be related to reduced wall motion, sound blood supply to the P-PM and the existence of a defect in the anterior left ventricular wall overlapping the P-PM. When we analyze the planar ²⁰¹Tl myocardial scintigram, not only the left and right ventricles, but also the PM should be assessed.