What is myocardial bridge

We don’t often see the name myocardial bridge in our lives because myocardial bridge is a disease that has a huge impact on human health. This disease is likely to cause vascular compression in patients, and in severe cases it may even put the patient’s life in danger. When a friend around you suffers from this disease, you must go to the hospital for examination in time and actively cooperate with the doctor's treatment.

1. Inspection

1. Coronary angiography

If coronary artery systolic stenosis or delayed diastolic relaxation is found, it indicates the presence of myocardial bridge. However, coronary angiography can only detect myocardial bridges that significantly affect coronary blood flow. The detection of myocardial bridge is related to its length, the direction of the bridge fibers, and the tissue between the bridge and the related artery. Some myocardial bridges are difficult to detect by angiography because their proximal coronary arteries are almost completely occluded or fixed stenosis caused by atherosclerosis limits coronary blood perfusion and masks their systolic stenosis, or because of the presence of vasospasm. Coronary angiography often fails to reveal atherosclerotic stenosis at the myocardial bridge.

2. Intracoronary Doppler examination

It was found that the coronary blood flow velocity in the myocardial bridge part increased significantly in the early diastole, forming a peak value, then quickly decreased, followed by a platform, until it decreased again in the systole. The peak value appears due to the existence of maximum perfusion pressure in the coronary artery and the corresponding continuous decrease in vascular area, which leads to a significant pressure gradient at both ends of the myocardial bridge. When the myocardial bridge relaxes during diastole, the pressure gradient at both ends disappears, the vascular area expands rapidly, and the blood flow velocity also decreases rapidly.

3. Intravascular Ultrasound

It can be found that atherosclerosis is often found in the coronary artery proximal to the myocardial bridge. Intracoronary Doppler ultrasound revealed a decrease in intracoronary blood flow reserve.

2. Diagnosis

In addition to clinical symptoms and corresponding electrocardiogram changes, the diagnosis of myocardial bridge still depends on coronary angiography, intracoronary Doppler and ultrasound examinations. The superficial type is difficult to diagnose because it is asymptomatic or has mild symptoms. Even coronary angiography can only detect deep myocardial bridges.

Treatment

The principle of treatment for myocardial bridge is to relieve the compression of the coronary artery below the myocardial bridge. Drug or surgical treatment can be used for patients with symptomatic myocardial bridge and atherosclerotic plaques at the myocardial bridge.

1. Medication

Angina caused by systolic coronary artery compression responds to beta-blockers, calcium antagonists (eg, verapamil and diltiazem), and antiplatelet drugs.

2. Surgery

Those who are difficult to control with drug therapy should undergo surgical treatment. There are two surgical procedures: myocardial resection and coronary artery bypass grafting.

(1) Myocardial bridge resection is suitable for superficial types. Under normal temperature general anesthesia, the myocardial bridge is found and removed to completely relieve the pressure on the coronary artery and restore its distal blood flow. Simple myocardial resection is rarely performed simultaneously with coronary artery bypass grafting.

(2) Coronary artery bypass grafting is suitable for patients with deep or combined arteriosclerotic stenosis. Coronary artery bypass grafting can be performed under normothermic general anesthesia, normothermic extracorporeal circulation, or hypothermic extracorporeal circulation. The graft material can be autologous great saphenous vein or internal mammary artery.