[Evaluation of right ventricular wall contractility in ischemic heart disease by cardiac computed tomography].

One hundred and eight cases with ischemic heart disease except for acute myocardial infarction were examined by cardiac computed tomography with ECG-gated scanning. The right ventricular (RV) wall contractility was evaluated by the long-axial and short-axial CT images in terms of (a) contraction rate of the RV area, (b) shortening rate of the RV free wall and (c) changes in the thickness of the RV free wall in cardiac cycle. These parameters were compared to the findings of coronary angiography and left ventriculography. 1. There was no difference of the contraction rate of the RV area between the cases with severe (90-100%) right coronary (RCA) stenosis and those with mild (0-75%) stenosis, while the contraction rate of the RV area was markedly decreased in the former combined with the impaired contraction of the ventricular septum. Consequently, it was assumed that RV function is hardly damaged by RCA lesion alone, and that the contraction rate of the RV area is not a suitable parameter for the assessment of the severity of RCA stenosis. 2. The shortening rate of the RV free wall in the long-axial image in cases with severe RCA stenosis was significantly decreased (14.5 +/- 4.6%) compared with that of mild stenosis (27.8 +/- 5.0%). The changes in the thickness of the RV free wall were also impaired in severe RCA stenosis. Same tendency was observed in the short-axial image, while the correlation between RCA stenosis and impaired contraction of the RV free wall was much more evident in the long-axis image than in the short-axis image. As the result, reduced RV contraction due to RCA ischemia seems to exist not only in acute myocardial infarction but also in chronic stage of the ischemic heart. 3. CT method is suitable for the evaluation of RV ischemia due to RCA lesion because the contractility of the RV free wall can be assessed independently of ventricular septal contraction. In cases with reduction of the free wall shortening rate under 20% combined with poor change in the thickness of the RV free wall, severe stenosis of the RCA should be suspected.