Author + information
- Received August 21, 1996
- Revision received February 10, 1997
- Accepted February 21, 1997
- Published online June 1, 1997.
- Shintaro Beppu, MD, FACCA,* (, )
- Hisao Matsuda, MDB,
- Toshiaki Shishido, MDB and
- Kunio Miyatake, MD, FACCB
- ↵*Dr. Shintaro Beppu, Osaka University Faculty of Medicine, School of Allied Health Sciences, 2-2, Yamadaoka, Suita, Osaka 565, Japan.
Objectives. The aim of this study was to clarify how myocardial perfusion is impaired by asynchronous contraction.
Background. False septal hypoperfusion is noted in some patients with left bundle branch block.
Methods. Eight dogs were examined with epicardial pacing at the left ventricular posterior wall, the right ventricular anterior wall and, as a control, the right atrial appendage. The pacing rate was 80, 110 and 150 beats/min (bpm). Myocardial perfusion was assessed by contrast echocardiography.
Results. Left ventricular pacing at 80 and 110 bpm did not change systolic wall thickening or contrast intensity at the pacing site, although an early excitation notch was noted at the pacing site. However, at 150 bpm, systolic thickening was impaired (23.3 ± 4.2% vs. 37.0 ± 2.6% during atrial pacing, p < 0.05), and the peak intensity ratio of the pacing site to the ventricular septum was significantly decreased (24.1 ± 5.7% vs. 37.0 ± 2.8% at a pacing rate of 80 bpm, p < 0.01). The peak intensity ratio correlated with systolic wall thickening at the pacing site (y = 0.413 × −0.028, r = 0.81, p < 0.0001). However, right ventricular pacing did not change either systolic thickening or the peak intensity ratio at any pacing rate, although an early excitation notch was noted on the ventricular septum.
Conclusions. Wall motion abnormalities after early excitation vary depending on the pacing mode. When tachycardia induces regional wall motion abnormalities, the ventricular wall of the pacing site is functionally hypoperfused.
(J Am Coll Cardiol 1997;29:1632–8)
☆ This study was supported in part by “Grant in Aid for Scientific Research (A) 07557344 from the Ministry of Education, Science, Sports and Culture of Japan, Tokyo, Japan.
- Received August 21, 1996.
- Revision received February 10, 1997.
- Accepted February 21, 1997.
- The American College of Cardiology