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Cardiac Stress Test Induced by Dobutamine and Monitored by Cardiac Catheterization in Mice
Published on: February 10, 2013
[The hemodynamic effect of dobutamine stress on myocardial bridging-mural coronary artery]
Guo-hui Zhang1, Jun-fang Guo, Ya Zhen
1Department of Cardiology, The First People's Hospital of Zhenjiang, Zhenjiang 212002, China.
Insights
Stress significantly increases intramural coronary artery compression and reduces coronary flow reserve (CFR) in patients with myocardial bridging (MB). This suggests that physical activity may induce myocardial ischemia in individuals with MB.
Area of Science:
- Cardiology
- Physiology
- Diagnostic Imaging
Context:
- Myocardial bridging (MB) is a congenital anomaly where a segment of a coronary artery tunneled through heart muscle.
- While often benign, MB can lead to myocardial ischemia, infarction, and sudden cardiac death, particularly during physical exertion.
- Intracoronary Doppler is a valuable tool for assessing coronary blood flow dynamics.
Purpose:
- To investigate the impact of stress on blood flow within the mural coronary artery of MB patients.
- To quantify changes in coronary artery diameter and flow velocity under dobutamine-induced stress.
- To evaluate the coronary flow reserve (CFR) proximal and distal to the myocardial bridge during stress.
Summary:
- The study assessed 8 MB patients using intracoronary Doppler during dobutamine infusion.
- Dobutamine significantly increased mural coronary artery compression (from 51.7% to 90.0%) and peak blood flow velocities.
- Coronary flow reserve (CFR) significantly decreased both proximal and distal to the MB during stress.
Impact:
- Stress significantly exacerbates coronary artery compression and impairs CFR in MB patients.
- These findings highlight the potential for exercise-induced myocardial ischemia in individuals with myocardial bridging.
- The study underscores the importance of evaluating coronary hemodynamics under stress in MB patients.
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).
Conclusion:
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.
