Asian Cardiovasc Thorac Ann 1998;6:150
© 1998 Asia Publishing EXchange Pte Ltd
Clinical Significance of Isolated Coronary Bridges
Aditya Kapoor, MD,
Satyendra Tewari, MD
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Department of Cardiology Sanjay Gandhi Post Graduate Institute of Medical Sciences Raebareli Road Lucknow 226014, India
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We read with interest the paper entitled Clinical Significance of Isolated Coronary Bridges by Gao and colleagues1 recently published in the Asian Annals. We would like to make some comments in this regard. We entirely agree with the authors that a myocardial bridge can no longer be considered a benign coronary anomaly. Angina, myocardial infarction, and even sudden death during exercise have been described in association with a myocardial bridge.2–4 The authors state that none of their patients had angiographic evidence of atherosclerosis in the bridged segment or the distal artery. Although several studies have reported the protective effect of the myocardial bridges on the distal artery, routine angiography may not detect an atherosclerotic lesion at the site or beyond a myocardial bridge. With the availability of intravascular ultrasound, a better insight may be provided in this regard.
The availability of Doppler flow studies offers a novel way to study the hemodynamics within a myocardial bridge.5 Within a myocardial bridge there is an abrupt early diastolic flow acceleration, rapid mid-diastolic deceleration, followed by a mid late diastolic plateau. In addition, there is retrograde systolic flow in the segment proximal to the most severe site of the bridge. This occurs because normally in early diastole there is a fall in peripheral coronary vascular resistance along with an increase in the coronary flow. Due to luminal narrowing in the myocardial bridge, this increased flow is associated with an early diastolic flow acceleration. The vessel relaxation and subsequent luminal gain then lead to a fall and plateau in later diastole. Furthermore, these abnormal hemodynamics are abolished after placement of an intracoronary stent within the myocardial bridge. Although the authors state that myotomy is now being reported as a definitive treatment for myocardial bridging, intracoronary stenting when indicated also offers a novel and efficacious modality for the treatment of such patients.5,6
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