Myocardial bridge
Encyclopedia
A myocardial bridge occurs when one of the coronary arteries
tunnels through the myocardium
rather than resting on top of it. Typically, the arteries rest on top of the heart muscle and feed blood down into smaller vessels that populate throughout the myocardium. But if the muscle grows around one of the larger arteries, then a myocardial bridge is formed. As the heart squeezes to pump blood, the muscle exerts pressure across the bridge and constricts the artery. This defect is present from birth. It can lead to uncomfortable, powerful heartbeats and angina. The incidence of the condition in the general population is estimated at 5% based on autopsy
findings, but significance when found in association with other cardiac conditions is unknown.
The condition is diagnosed on a scaled based on what percentage of obstruction occurs. If there is less than 50% blockage, then the condition is probably benign. A result of at least 70% usually causes some pain. Small amounts of myocardial bridging often are undetectable, as the blood usually flows through the coronary while the heart is relaxing in diastole
.
This condition can cause complications such as vasospasm
, angina pectoris, arrhythmia, Vtach. Additionally many patients express discomfort in specific positions, (i.e. lying on the left side for a prolonged period of time).
Coronary circulation
Coronary circulation is the circulation of blood in the blood vessels of the heart muscle . The vessels that deliver oxygen-rich blood to the myocardium are known as coronary arteries...
tunnels through the myocardium
Cardiac muscle
Cardiac muscle is a type of involuntary striated muscle found in the walls and histologic foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle...
rather than resting on top of it. Typically, the arteries rest on top of the heart muscle and feed blood down into smaller vessels that populate throughout the myocardium. But if the muscle grows around one of the larger arteries, then a myocardial bridge is formed. As the heart squeezes to pump blood, the muscle exerts pressure across the bridge and constricts the artery. This defect is present from birth. It can lead to uncomfortable, powerful heartbeats and angina. The incidence of the condition in the general population is estimated at 5% based on autopsy
Autopsy
An autopsy—also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction—is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present...
findings, but significance when found in association with other cardiac conditions is unknown.
The condition is diagnosed on a scaled based on what percentage of obstruction occurs. If there is less than 50% blockage, then the condition is probably benign. A result of at least 70% usually causes some pain. Small amounts of myocardial bridging often are undetectable, as the blood usually flows through the coronary while the heart is relaxing in diastole
Diastole
Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
.
This condition can cause complications such as vasospasm
Vasospasm
Vasospasm refers to a condition in which blood vessels spasm, leading to vasoconstriction. This can lead to tissue ischemia and death . Cerebral vasospasm may arise in the context of subarachnoid hemorrhage. Symptomatic vasospasm or delayed cerebral ischemia is a major contributor to...
, angina pectoris, arrhythmia, Vtach. Additionally many patients express discomfort in specific positions, (i.e. lying on the left side for a prolonged period of time).
Case study
Figure 1 shows a series of angiographic images with a bridge on the left anterior descending coronary artery (LAD) in a male patient of 65 years.- A1) Right anterior oblique view taken at end systole. The compressed vessel segment is indicated by the two arrows.
- B1) Left anterior oblique view taken nearly at the same instant.
- A2) Same view as in A1, but taken 133 ms later. The tunneled segment is no longer compressed.
- B2) Same view as in B1 but 133 ms later.