Internal medicine guidance: What examination should be made for myocardial bridge?

1. If coronary angiography finds coronary artery systolic stenosis or diastolic delay, it indicates the existence of myocardial bridge. However, coronary angiography can only detect those myocardial bridges that have a significant impact on coronary blood flow. The detection of myocardial bridge is related to its length, the direction of muscle bridge fibers and the tissue between myocardial bridge and related arteries. Some myocardial bridges are difficult to find by angiography because of the almost complete occlusion of the proximal coronary artery or the fixed stenosis caused by atherosclerosis, or because of the existence of vasospasm, thus covering up their systolic stenosis. Coronary angiography often fails to find atherosclerotic stenosis at myocardial bridge.

2. Doppler examination in coronary artery showed that the coronary blood flow velocity of myocardial bridge increased obviously in the early diastolic period, reaching a peak value, then decreased rapidly, then showed a plateau period, and then decreased again in systolic period. The peak value is due to the existence of perfusion pressure in coronary artery, and the corresponding vascular area is decreasing, resulting in obvious pressure gradient between the two ends of myocardial bridge. When the myocardial bridge relaxes, the pressure gradient at both ends disappears, the blood vessel area expands rapidly and the blood flow velocity decreases rapidly.

3. Intravascular ultrasound can find that atherosclerosis often forms in coronary artery near myocardial bridge. The decrease of coronary blood flow reserve was detected by intracoronary Doppler.