[The hemodynamic effect of dobutamine stress on myocardial bridging-mural coronary artery].
OBJECTIVE
Patient with myocardial bridging (MB) usually has a benign prognosis, but some MB patients might experience myocardial ischemia, infarction and sudden cardiac death, especially during active physical activities. The purpose of the study was to study the stress-induced blood flow changes of the mural coronary artery in MB patients determined by intracoronary Doppler.


METHODS
In 8 patients with MB, the basic average peak velocity (bAPV), hyperemic average peak velocity (hAPV) of blood flow, coronary flow reverse (CFR) proximal and distal to the mural coronary artery were measured before and during intravenously dobutamine (10 microg kg-1 min-1, then add 10 microg kg-1 min-1 at 3 min interval till 40 microg kg-1 min-1) by intracoronary Doppler.


RESULTS
The baseline mural coronary diameter reduction was (51.7+/-21.4)% and significantly increased to (90.0+/-12.7)% (P<0.01) during dobutamine infusion. bAPV on the segments proximal and distal to the mural coronary artery significantly increased from (19.83+/-5.84) cm/s and (20.75+/-4.91) cm/s to (31.52+/-10.93) cm/s and (30.46+/-9.01) cm/s (all P<0.05 vs. baseline) respectively post dobutamine infusion. CFR measured at proximal and distal to myocardial bridging also significantly decreased from (2.91+/-0.62) and (2.46+/-0.82) to (2.17+/-0.66) and (1.83+/-0.51) (all P<0.01).


CONCLUSIONS
Stress can significantly increase the compression of intramural coronary artery and reduce CFR on coronary segments both proximal and distal to the MB. Thus, active exercise might induce myocardial ischemia in patients with myocardial bridging.
Zhang
Guo-hui
GH
Department of Cardiology, The First People's Hospital of Zhenjiang, Zhenjiang 212002, China.
Guo
Jun-fang
JF
Zhen
Ya
Y
Li
Wei-dong
WD
Bao
Zhong-hua
ZH
Jiang
Hong
H
Qian
Ju-ying
JY
Fan
Bing
B
Ge
Jun-bo
JB
D001783:Blood Flow Velocity; D002316:Cardiotonic Agents / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects*; D003330:Coronary Vessel Anomalies / Q000503:physiopathology*; D003331:Coronary Vessels / Q000187:drug effects; D004280:Dobutamine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
D002316:Cardiotonic Agents; D004280:Dobutamine