Coronary Artery Fistula. Symptoms and Treatment

Coronary artery fistulas are the most common coronary artery anomalies that can change the blood flow in the heart and blood pressure.

A coronary artery fistula is an unusual connection between a coronary artery (an artery supplying blood to the heart muscle) and other areas of the circulatory system, such as one of the heart's chambers or another blood vessel.

Most of the time, these defects do not cause symptoms and may remain completely unnoticed, but in some situations, they can lead to severe, even life-threatening complications.

Coronary artery fistulas are rare and can either be congenital (present at birth) or acquired (developed over time).

Normal heart function

In a normal heart's structure, the coronary arteries are the first to branch off the aorta, the main blood vessel bringing blood to the body. They surround the outside of the heart and supply oxygen and nutrients to the heart muscle.

The defect

Coronary heart fistulas can fit into two general categories:

• Coronary-cameral fistulas are unusual connections between the coronary arteries and one of the four heart chambers (atria or ventricles).
• Coronary arteriovenous fistulas are unusual connections between the coronary arteries and other blood vessels.

The most common place for a coronary fistula to originate is in the right coronary artery. The most common insertion site is the right ventricle, followed by the right atrium and the pulmonary arteries.

Overall, the most common coronary artery fistula originates in the left coronary artery and ends in one of the pulmonary arteries (the arteries leading to the lungs).

Causes

Most coronary artery fistulas are present at birth, as the arteries supplying blood to the heart do not form correctly. This heart defect may be isolated or associated with other congenital heart defects.

Coronary artery fistulas can also occur after birth. The most common cause of acquired coronary artery fistulas is trauma, such as a stab wound, or a gunshot wound.

Acquired coronary artery fistulas can also begin after an infection weakens the heart or coronary artery or after cardiac procedures, such as a coronary artery bypass graph, heart valve replacements, or biopsies.

Symptoms

Symptoms start to develop when the hemodynamics (blood pressure and blood flow) in the body are affected enough to change the circulation of blood through the body.

The severity of symptoms depends on:

• The location of the fistula.
• The insertion site.
• The length.
• The amount of blood shunted (moved from where it should be to a different location).

Infants with a coronary artery fistula significant enough to cause symptoms usually have signs of congestive heart failure.

• Irritability.
• Tiring easily.
• Restlessness.
• Difficulty breathing.
• Excessive sweating.
• Tachypnea (rapid breathing).
• Continuous murmur heard through a stethoscope.
• Tachycardia or heart arrhythmias (fast heart rate or irregular heart rate).

Generally, symptoms that develop in adults don't appear until at least 20 years after the development of the fistula, and the possibility of symptoms and complications increases with age.

If symptoms do occur, they may include:

• Heart murmur.
• Chest pain.
• Shortness of breath.
• Dyspnea on exertion.
• Difficulty breathing while lying down.
• Swelling in the legs.
• Heart palpitations or heart arrythmias.
• Hypotension (low blood pressure).
• Jugular vein distention (distended neck veins).

Diagnosis

A doctor may notice a continuous heart murmur as the first symptom, but most are found incidentally during a coronary angiogram to assess a different medical issue.

If your doctor is concerned, they may order additional tests, including:

• Coronary computerized tomography angiography (CTA).
• Transthoracic echocardiogram (TTE).
• Cardiac catheterization.
• Ultrasound of the heart.
• Cardiac angiogram.
• Chest x-ray.
• MRI.
• EKG.

Treatment

Some coronary artery fistulas will close on their own.

Even if it does not close on its own, treatment is only needed if the left to right shunt is:

• Affecting blood pressure or blood flow in the hear.
• You are having symptoms of congestive heart failure.
• You have myocardial ischemia (heart muscle damage) due to the fistula.

Usually, the fistula is closed during a procedure called cardiac catheterization. A doctor will insert a catheter into the bloodstream, thread it up to the fistula origin site, place a detachable balloon or steel/platinum micro coils at the opening of the fistula, then remove the catheter.

Your doctor will probably recommend a coronary angiogram after the procedure to ensure success and check for more, smaller fistulas.

Your doctor will usually prescribe medication to prevent blood clots for at least six months after the procedure, and you will need regular follow-up appointments with your doctor.

Complications

Most cases of coronary artery fistula do not lead to symptoms or long-term problems.

In cases that do progress far enough to cause problems, the complications include:

• Congestive heart failure can result if too much blood shunts to one of the heart's chambers or arteries.
• Coronary "steal" syndrome occurs when blood that should be flowing to a particular part of the heart muscle is "stolen" by the fistula. Decreased blood flow and oxygen in the area causes ischemia (damage to the heart muscle resulting from lack of oxygen), which can cause chest pain and heart attack.
• A blood clot can form where the fistula begins and block blood flow, leading to cardiac ischemia and a heart attack.
• Aneurysms may form at the opening of the fistula.
• Too much blood shunted to one area of the circulatory system can lead to heart failure.
• Heart failure can cause a backup of blood flow, leading to dilated heart chambers. The irritation and damage can cause arrhythmias (irregular heart rhythms).
• Rupture of the fistula can lead to hemopericardium (blood in the sack around the heart).
• Hemopericardium can cause cardiac tamponade (the heart cannot pump effectively due to compression from the blood around the heart).
• Pulmonary hypertension (high blood pressure in the arteries leading to the lungs) can result if too much blood shunts into the right ventricle or the pulmonary arteries.