Introduction
In the coronary circulation system, coronary artery fistulas are rare defects that can be congenital or acquired malformations in the assembly and circulation of coronary arteries. Coronary artery fistulas occur when there is an abnormal connection between coronary arteries and any of the heart chambers and can be grouped into two broad categories. The abnormal connections are coronary arteriovenous malformations between coronary arteries and parts of systemic or pulmonary circulatory vessels. Coronary artery fistula is diagnosed by the majority incidentally on coronary catheterization, and sometimes, patients with this disease are also diagnosed with signs and symptoms of myocardial infarction, congestive heart failure, pulmonary hypertension, and other cardiopulmonary functional abnormalities. Highly reliable diagnostic tools for coronary artery fistulas are coronary angiography and coronary computerized tomography angiography (CTA); the main treatment modality is catheterized closure.
What Is a Coronary Artery Fistula?
Coronary artery fistula is a rare condition that occurs when there is an abnormal connection between one of the coronary arteries and another heart chamber or blood vessel. Usually, the blood is supplied to the heart by the coronary artery, and the blood flow can be affected due to coronary artery fistula to the heart and lead to the dilation of the coronary artery. Sometimes, infants who are born with this condition may also have other heart defects.
What Is the Etiology of Coronary Artery Fistula?
The causes of coronary artery fistula due to three major reasons: it arises congenitally as a result of abnormal embryonic development acquired coronary artery fistulas that result from trauma that includes gunshot wounds or stab injuries, and another cause of coronary artery fistula is due to iatrogenic. These iatrogenic causes include interventional cardiac procedures such as cardiac angiography, coronary artery bypass grafting, device implantations, valve replacements, or biopsies.
What Is the Pathophysiology of Coronary Artery Fistula?
The pathophysiology of coronary artery fistula can lead to several cardiopulmonary functional abnormalities. Depending on the origin, site of insertion, length of the fistula, and volume of the blood that is shunted, the severity of presenting symptoms will depend. The most common site of origin is the right coronary artery, followed by the left coronary artery. The most common to least common insertion sites are the right ventricle, right atrium, and pulmonary arteries. The pathophysiology of coronary artery fistula is that these aberrant coronary arteries have thicker tunica intima and thicker tunica media tightly packed with smooth muscle cells.
How Is Coronary Artery Fistula Evaluated?
The coronary artery fistula can be evaluated by beginning with the auscultation of the continuous murmur over the lower precordium. Chest radiography and electrocardiography are the initial diagnostic examinations. These modalities can uncover any ensuing complications, though they do not yield a sufficient diagnosis. Studies show that significant coronary artery fistulas are visualized hemodynamically with trans thoracic electrocardiogram and are sufficient to diagnose this disease in children but do not help determine sites of origin and termination. The dilated or tortuous arteries can be pinpointed with the help of electrocardiography and are also helpful in mapping out the blood flow. The gold standard tools for diagnosing coronary artery fistulas are coronary catheterization and subsequent coronary angiography.
What Are the Symptoms of Coronary Artery Fistula?
Usually, the symptoms of coronary artery fistula in children are asymptomatic, but if the symptoms are present, it include chest pain, slow growth, fast or irregular heartbeat, failure to thrive, easy fatigue, heart murmur, and shortness of breath.
What Is the Treatment for Coronary Artery Fistula?
Coronary artery fistula can be further managed and treated only in patients with myocardial ischemia, hemodynamically significant left to right shunt, and congestive heart failure with either left ventricular dysfunction or left ventricular volume overload.
The coronary artery can be repaired surgically, but the best treatment of choice is catheterized closure. In catheterized closure, the artery is embolized at the most distal aspect at the fistula, which is the objective closest to the termination site. The rationale is to ensure that the tissues supplied by the aberrant artery are still perfused and decrease blood shunting through the fistula. The embolization can be achieved using detachable balloons or steel or platinum micro-coils. A post-procedure coronary angioplasty is performed after the embolization to ensure the embolization is successful and to visualize small fistulas or branches from the fistula. Though surgical repairs were used in the past, it had a higher level of fistula recurrence, and therefore, catheterized closure is preferred.
What Is the Differential Diagnosis of Coronary Artery Fistula?
The differential diagnosis of coronary artery fistula in patients presenting with signs and symptoms are arrhythmia, cardiac tamponade, congestive heart failure, acute myocardial infarction, and patent ductus arteries. The presenting signs of a hemodynamically stable coronary artery fistula could have these few conditions. Still, it is essential to exclude other more serious underlying etiologies such as secondary to thrombosis, myocardial infarction, and primary ventricular arrhythmias.
What Are the Complications of Coronary Artery Fistula?
Complications due to coronary artery fistula are usually asymptomatic, and patients with coronary artery fistula are secondary to complications. The complications that are seen due to coronary artery fistulas are thrombosis or embolism that will lead to myocardial infarction, volume overload that will lead to cardiac failure, arrhythmias, a rupture that will lead to hemopericardium and cardiac tamponade, endocarditis, and steal syndrome. In this syndrome, the blood is shunted away through the fistula, where the distal blood flow is decreased to the distal part of the original artery, leading to myocardial infarction.
What Is the Life Expectancy of Coronary Artery Fistula?
There are no symptoms in many individuals with coronary artery fistula, and this makes it difficult for doctors to detect the condition early. The accurate life expectancy of the individual with this condition is also difficult to estimate. Sometimes, the coronary artery fistula can lead to heart attacks and congestive heart failure. This disease is often benign in many individuals.
Conclusion
Coronary artery fistula is a rare condition which is the irregular connections between the coronary arteries and other parts of the circulatory system. In the majority of individuals, this fistula is asymptomatic for many years, but in some cases, the coronary artery fistula can sometimes lead to health issues, such as heart attack and congestive heart failure.
