OVERVIEW

What is a myocardial bridge?

A myocardial bridge, as the name suggests, is a "bridge" formed by heart muscle. However, what flows beneath it is not water but a coronary artery, through which blood circulates, resembling water flowing under a bridge.

In other words, a myocardial bridge refers to the heart muscle that spans over a coronary artery. The coronary artery beneath the myocardial bridge is called a "tunneled artery."

Normally, coronary arteries run along the surface of the heart muscle. When the myocardial bridge contracts, it compresses the coronary artery, affecting blood flow and, consequently, the heart's blood supply, leading to a range of symptoms.

What is a coronary artery?

The heart is an organ in the human body, and its function also requires a blood supply. The blood vessels supplying the heart resemble a "crown" covering the heart, hence they are called coronary arteries, or simply "coronaries."

Coronary arteries originate from the root of the aorta (the largest artery in the body) and run along the surface of the heart (beneath the epicardium and above the myocardium). They branch into smaller vessels to nourish the heart muscle, primarily dividing into major branches such as the left anterior descending artery, circumflex artery, and right coronary artery.

Is a myocardial bridge common?

Myocardial bridges are widespread in the population, though many people remain unaware of them and experience no symptoms. However, some may develop severe manifestations.

Most myocardial bridges can be considered a normal anatomical variation with no significant clinical implications.

Which coronary arteries are primarily affected by myocardial bridges?

Theoretically, myocardial bridges can involve any epicardial coronary artery, but they most commonly affect the left anterior descending artery.

Additionally, the length and severity of the affected vessel vary greatly among individuals. Some may involve a long segment of the coronary artery, while others affect only a short portion. In rare cases, even coronary branches may be involved, leading to diverse clinical presentations.

Which medical department should be consulted for a myocardial bridge?

Myocardial bridges fall under coronary artery diseases in cardiology. Therefore, patients should visit the cardiovascular medicine department (also called cardiology in some hospitals). If surgery is required, they may also consult the interventional radiology department.

SYMPTOMS

What are the symptoms of myocardial bridging?

Due to myocardial contraction, the coronary artery beneath the bridge is compressed, causing vascular narrowing and myocardial ischemia. This can lead to symptoms such as angina pectoris or even myocardial infarction. In rare cases, it may result in sudden death (often discovered during autopsy after death). However, a significant portion of individuals may remain asymptomatic, making the condition benign and non-threatening.

What severe consequences can myocardial bridging cause? Is it life-threatening?

Myocardial bridging compresses the underlying coronary artery, leading to ischemia in the distal myocardium and affecting blood flow. This also increases the likelihood of atherosclerosis in the proximal coronary artery. Severe cases may result in myocardial infarction or even sudden death, so myocardial bridging requires special attention.

However, most cases are asymptomatic and have a good prognosis, so there is no need for excessive concern.

CAUSES

What is the cause of myocardial bridging?

It is currently considered a congenital anatomical variation, meaning it is caused by developmental abnormalities.

Who is more likely to have myocardial bridging?

Myocardial bridging is generally common in the population.

Some small-scale studies have shown a very high incidence of myocardial bridging in children and adults with hypertrophic cardiomyopathy, but these studies also indicate that myocardial bridging does not increase the risk of sudden death.

Is myocardial bridging hereditary?

Although no specific genes have been found to be associated with myocardial bridging, the possibility of potential heredity cannot be ruled out.

DIAGNOSIS

What tests are needed to confirm the diagnosis of suspected myocardial bridging?

• For the diagnosis of myocardial bridging, symptoms are an important reference. For patients with angina attacks but without conventional risk factors for coronary artery disease (such as hypertension, hyperlipidemia, diabetes, etc.), especially young patients, the possibility of myocardial bridging should be considered.

• For the diagnosis of myocardial bridging, conventional tests such as electrocardiograms cannot confirm the diagnosis. Only coronary angiography can provide a definitive diagnosis, as it allows visualization of the dynamic compression of the coronary artery by the myocardial bridge—narrowing during myocardial contraction and restoration during myocardial relaxation.

• Non-invasive tests such as coronary CTA can also be used for evaluation, but the detection rate is lower than that of coronary angiography, and it is more difficult to observe the dynamic compression of the coronary artery by the myocardial bridge.

• For patients with a high suspicion of myocardial bridging, coronary CTA can be used for initial screening. If no organic coronary stenosis or complicating myocardial bridging is found, it can generally be concluded that the symptoms are likely caused by myocardial bridging. If other coronary stenoses are present, coronary angiography is then required for clarification.

What precautions should be taken for myocardial bridging-related tests?

Coronary CTA can be performed on an outpatient basis. Before the test, a routine electrocardiogram is required, but fasting is not necessary—it can be done at any time. Coronary angiography requires hospitalization and preoperative preparation before it can be performed.

Which diseases is myocardial bridging easily confused with? How can they be distinguished?

The most important distinction is between angina caused by primary coronary artery disease (leading to coronary stenosis) and angina caused by myocardial bridging. Coronary angiography is needed for differentiation.

If coronary angiography shows dynamic changes in coronary stenosis corresponding to myocardial contraction and relaxation, it indicates myocardial bridging. If the coronary stenosis is fixed and unchanging, it suggests primary coronary artery disease.

If typical angina or other discomfort occurs, medical attention should be sought, and coronary angiography may be necessary for a definitive diagnosis.

TREATMENT

When does myocardial bridging require treatment?

• For most people, if there are no symptoms and no other risk factors, no treatment is necessary;

• If myocardial bridging causes frequent angina, significant symptoms, or if there is a clear pre-existing heart condition, immediate consultation with a specialist is required, and hospitalization may be necessary. Of course, whether treatment is needed should be evaluated by a doctor.

What medications can treat myocardial bridging if treatment is needed?

If angina occurs, symptoms are primarily relieved through medication, with beta-blockers such as metoprolol being the first choice. Non-dihydropyridine calcium channel blockers, such as diltiazem, can also be used. These medications reduce heart rate and suppress myocardial contraction, thereby alleviating angina symptoms.

Although myocardial bridging also involves vascular narrowing, this narrowing is caused by compression from the myocardial bridge. Common nitrate medications, such as nitroglycerin, are contraindicated because they increase myocardial contractility and may worsen angina symptoms.

Does myocardial bridging require long-term medication? Are there side effects?

Generally, symptomatic patients require long-term medication.

Medications have therapeutic effects but often come with side effects. Both metoprolol and diltiazem can slow heart rate and suppress myocardial contraction. The main side effect is potential bradycardia, requiring heart rate monitoring to adjust dosage.

Medication should only be used after a doctor's evaluation confirms it is necessary and the benefits outweigh the side effects.

Can myocardial bridging be treated with surgery?

Surgical treatments mainly include minimally invasive stent placement and open surgery.

• Although coronary stent implantation can restore blood flow and improve clinical symptoms, current research shows that stents placed in the tunneled coronary artery under the myocardial bridge are prone to restenosis, often requiring repeat surgery with limited effectiveness and a risk of coronary rupture. Therefore, stent therapy is not currently recommended.

• Open surgery involves directly cutting the myocardial bridge to free the underlying coronary artery, relieving compression. However, this approach is only suitable for patients with persistent symptoms, myocardial ischemia, high-risk factors for sudden death (such as malignant arrhythmias), and ineffective medical treatment. This procedure is relatively rare, and its effectiveness and prognosis require further study.

What are the common risks of surgical treatment for myocardial bridging?

Potential risks include bleeding, vascular rupture, cardiac rupture, thrombosis, cardiac tamponade, arrhythmia, heart failure, and sudden death. For minimally invasive surgery, the main long-term risk is a high rate of stent restenosis.

Does myocardial bridging require regular follow-up?

• For most asymptomatic individuals, routine physical examinations are sufficient, with no need for special tests targeting myocardial bridging.

• For patients with significant angina symptoms on long-term medication, regular follow-ups are necessary for professional evaluation and treatment adjustments. Additionally, myocardial bridging patients have a higher risk of coronary artery disease. If medication is ineffective, the possibility of coexisting coronary artery disease should be considered, and coronary angiography may be required.

• For the rare cases treated surgically, regular follow-ups are essential to assess surgical outcomes (with immediate medical attention for any discomfort). Typically, follow-ups are scheduled at 1 month, 3 months, and 6 months post-surgery, followed by annual check-ups.

Can myocardial bridging be completely cured?

Currently, myocardial bridging is difficult to cure completely, but medications can control symptoms and improve quality of life.

• Medications primarily relieve angina symptoms but do not provide a cure.

• Surgical treatments, such as stent placement, only expand the coronary artery and are not curative.

• Open surgery directly relieves compression but is rarely performed due to significant side effects and potential recurrence.

DIET & LIFESTYLE

What should patients with myocardial bridging pay attention to in their diet?

There are no specific dietary requirements for myocardial bridging itself. However, it is currently believed that patients with myocardial bridging are more prone to developing atherosclerosis in proximal blood vessels, meaning they have a higher incidence of coronary heart disease. Therefore, the focus should be on maintaining a healthy diet to reduce atherosclerosis. Specific examples include:

• Limit alcohol consumption and avoid coffee, strong tea, and sugary beverages.

• Adopt a low-salt, low-fat diet with less greasy food. Choose lean meats, especially white meats like chicken and fish.

• Increase the proportion of fruits, vegetables, whole grains, and nuts in the diet.

• Control food intake to avoid obesity.

What should patients with myocardial bridging pay attention to in daily life?

The fundamental mechanism of myocardial bridging involves myocardial compression of the coronary arteries. Therefore, in addition to dietary considerations, patients should avoid factors that intensify myocardial contraction. Key aspects include:

• Take prescribed medications as directed, attend regular follow-ups, and avoid adjusting medications or dosages without medical advice. Nitrate medications are strictly prohibited. Do not take other drugs casually or trust unverified advertisements. Seek medical attention promptly if symptoms change.

• Avoid lifestyle factors that may worsen the condition, such as smoking, alcohol, lack of rest, and overexertion.

• Avoid emotional agitation in daily life. Moderate exercise is acceptable, but strenuous activities should be avoided.

• Since myocardial bridging increases the risk of coronary heart disease, manage risk factors like high blood pressure, cholesterol, and blood sugar.

Can patients with myocardial bridging have children?

Myocardial bridging itself does not directly affect fertility but may impact a woman's ability to tolerate pregnancy. Patients with frequent angina episodes may struggle to endure pregnancy and should postpone childbearing until symptoms are well-controlled. If asymptomatic, myocardial bridging generally does not affect fertility.

Can patients with myocardial bridging fly, engage in strenuous exercise, or travel to high-altitude areas?

• If the condition is stable and asymptomatic, flying is generally permissible.

• Once symptoms are controlled, moderate exercise is tolerable. However, strenuous exercise, including competitive sports, should be avoided as it may trigger angina.

• Individuals with pre-existing heart conditions are advised against traveling to high-altitude areas due to hypoxia, which may induce or worsen heart disease.

• Young, otherwise healthy patients with well-controlled angina may travel to high-altitude areas but should take precautions against altitude sickness.

Does myocardial bridging affect normal study or work?

Some patients experience typical angina or even arrhythmias and coronary heart disease, requiring proper treatment. With effective medication, such individuals can study and work normally but should avoid excessive fatigue or high-intensity activities, which may worsen cardiac ischemia.

Whether myocardial bridging affects study or work depends on symptom presence and medication efficacy. Stable patients can generally maintain normal routines.

PREVENTION

Can Myocardial Bridging Be Prevented? How to Prevent It?

Myocardial bridging is primarily caused by congenital factors and is considered a congenital variation. Prevention can begin during the parents' reproductive stage, including: undergoing routine prenatal and premarital checkups; avoiding alcohol, tobacco, radiation, and medications during the conception period; and during pregnancy, avoiding factors that may affect the fetus, such as certain medications, radiation, alcohol, tobacco, and unclean food.

These measures aim to reduce the birth rate of unhealthy infants. If these risks are minimized, the incidence of myocardial bridging may also decrease.