Myocardial perfusion abnormality induced by right ventricular pacing: real-time myocardial contrast echocardiography study
Taniguchi, A.; Masuda, K.; Uranishi, A.; Asanuma, T.; Ishikura, F.; Beppu, S.
Journal of Cardiology 50(3): 183-191
2007
ISSN/ISBN: 0914-5087 PMID: 17941194 Document Number: 608985
False positive findings of coronary stenosis are frequently detected by exercise stress myocardial scintigraphy in patients with left bundle branch block (LBBB). We investigated the relationship between regional wall motion abnormality and myocardial perfusion abnormality at high right ventricular (RV) pacing rate in the region of the RV pacing (the ventricular septum) and the control region (the lateral wall) assuming exercise stress in patients with LBBB. RV pacing was performed in 7 open chest canines. Real time myocardial contrast echocardiography of the left right ventricular short-axis view was examined by Toshiba Aplio during infusion of the ultrasound contrast agent (Definity). The examination was performed at baseline without pacing and at high RV pacing. Replenishment curve of the myocardial opacification was obtained and fit to the equation of y = A (1 - e (-betat)) in the regions of the ventricular septum and the lateral wall. Wall thickening ratio (%WT) was calculated in both regions. Dyssynchronous motion was observed during high RV pacing, but no wall motion abnormality was seen in control conditions. Although %WT, A-value and beta-value were almost identical between both regions at baseline, %WT and beta decreased in the ventricular septum at high RV pacing. The value did not differ between two regions. We concluded that perfusion abnormality occurs with regional wall motion abnormality at high RV pacing based on real time myocardial contrast echocardiography.