Alteration of left ventricular function with dobutamine challenge in patients with myocardial bridge.
OBJECTIVE
The aim of this study was to identify changes in left ventricular (LV) performance in patients with a myocardial bridge (MB) in the left anterior descending coronary artery during resting and in an inotropic state.


METHODS
Myocardial strain measurement by speckle-tracking echocardiography and conventional LV wall-motion scoring was performed in 18 patients with MB (mean age, 48.1 ± 1.7 years, eight female) during resting and intravenous dobutamine challenge (10 and 20 µg/kg/min).


RESULTS
Conventional LV wall-motion scoring was normal in all patients during resting and in an inotropic state. Peak regional circumferential strain increased dose dependently upon dobutamine challenge. Longitudinal strains of the anterior and anteroseptal segments were, however, reduced at 20 µg/kg/min and showed a dyssynchronous pattern at 20 µg/kg/min. Although there were no significant differences in radial strain and displacement of all segments at rest compared with under 10 µg/kg/min challenge, radial strain and displacement of anterior segments at 20 µg/kg/min were significantly reduced compared with posterior segments at the papillary muscle level (44.8 ± 14.9% vs. 78.4 ± 20.1% and 5.3 ± 2.3 mm vs. 8.5 ± 1.8 mm, respectively; all p < 0.001), and showed plateau (40%) or biphasic (62%) patterns.


CONCLUSIONS
Reduced LV strain of patients with MB after inotropic stimulation was identified. Speckle-tracking strain echocardiography identified a LV myocardial dyssynchrony that was not demonstrated by conventional echocardiography in patients with MB.
Division of Cardiology, Department of Internal Medicine, Maryknoll Medical Center, Busan, Korea.
Joon-Hyung
JH
Jhi
Kyoung-Im
KI
Cho
Jong-Kun
JK
Ha
Chan-Woo
CW
Jung
Bong-Jae
BJ
Kim
Seong-Oh
SO
Park
A-Ra
AR
Jo
Seong-Man
SM
Kim
Hyeon-Gook
HG
Lee
Tae-Ik
TI
Kim
D058665:Adrenergic beta-1 Receptor Agonists; D000328:Adult; D000368:Aged; D002637:Chest Pain; D017023:Coronary Angiography; D003971:Diastole; D004280:Dobutamine; D025401:Echocardiography, Stress / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009206:Myocardium; D005082:Physical Exertion; D013599:Systole; D018487:Ventricular Dysfunction, Left; D016277:Ventricular Function, Left / Q000187:drug effects*
D058665:Adrenergic beta-1 Receptor Agonists; D004280:Dobutamine