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AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Andrew N Pelech, MD, Professor, Department of Pediatrics, Medical College of Wisconsin; Director of Cardiac Catheterization Laboratory, Cardiology Research Focus and Cardiology Database, Director of Herma Heart Center Clinical Research, Children's Hospital of Wisconsin; Chairman of Wisconsin Pediatric Cardiac Registry
Andrew N Pelech is a member of the following medical societies: American College of Cardiology, Canadian Cardiovascular Society, Canadian Medical Association, Canadian Paediatric Society, and Royal College of Physicians and Surgeons of Canada
Editors: Juan Carlos Alejos, MD, Associate Clinical Professor, Department of Pediatrics, Division of Cardiology, University of California at Los Angeles; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Julian M Stewart, MD, PhD, Director of Center for Pediatric Hypotension, Professor, Departments of Pediatrics and Physiology, Division of Pediatric Cardiology, Westchester Medical Center and New York Medical College; Gilbert Herzberg, MD, Assistant Professor, Department of Pediatrics, Section of Pediatric Cardiology, New York Medical College; Steven R Neish, MD, SM, Director of Pediatric Cardiology Fellowship Program, Department of Pediatrics, Baylor College of Medicine
Author and Editor Disclosure
Synonyms and related keywords:
coronary artery fistula, CAF, coronary cameral fistula, coronary arteriovenous fistula, heart disease, coronary fistula, cardiac anomalies, cardiac fistula, cardiac disease, coronary artery anomaly, coronary arterial-venous fistula, CAVF, coronary-pulmonary artery fistula
Background
Within the context of coronary artery anomalies, coronary fistulae are classified as abnormalities of termination. A coronary artery fistula (CAF) involves a sizable communication between a coronary artery, bypasses the myocardial capillary bed, and enters either a chamber of the heart (coronary-cameral fistula) or any segment of the systemic or pulmonary circulation (coronary arteriovenous fistula). The pathophysiology of these lesions is identical, and they often are collectively termed coronary arterial-venous fistulae (CAVFs). A coronary artery connection to the pulmonary artery (coronary-pulmonary artery fistula) also may be considered under this grouping; however, if a named coronary artery arises directly from the pulmonary trunk with absence of a direct aortic connection, this is classified as an anomalous origin of the coronary artery from the pulmonary artery.
Maude Abbott published the first pathological account of this condition in 1908. The first successful surgical closure of a coronary fistula was performed in 1947 by Bjork and Crafoord in a patient with a preoperative diagnosis of patent ductus arteriosus.
Pathophysiology
The pathophysiologic mechanism of CAF is myocardial stealing or reduction in myocardial blood flow distal to the site of the CAF connection. The mechanism is related to the diastolic pressure gradient and runoff from the coronary vasculature to a low-pressure receiving cavity. If the fistula is large, the intracoronary diastolic perfusion pressure diminishes progressively.
The coronary vessel attempts to compensate by progressive enlargement of the ostia and feeding artery. Eventually, myocardium beyond the site of the fistula's origin is at risk for ischemia, which is most frequently evident in association with increased myocardial oxygen demand during exercise or activity. With time, the coronary artery leading to the fistulous tract dilates progressively, which, in turn, may progress to frank aneurysm formation, intimal ulceration, medial degeneration, intimal rupture, atherosclerotic deposition, calcification, side-branch obstruction, mural thrombosis, and, rarely, rupture.
The factors that determine the hemodynamic significance of the fistulous connection include the size of the communication, the resistance of the recipient chamber, and the potential for development of myocardial ischemia. Occasionally, high output congestive heart failure has been described.
Anatomy
Normally, 2 coronary arteries arise from the root of the aorta and taper progressively as they branch to supply the cardiac parenchyma. A fistula exists if a substantive communication arises that bypasses the myocardial capillary phase and communicates with a low-pressure cardiac cavity (atria or ventricle) or a branch of the systemic or pulmonary systems.
Normal thin-walled vessels exist at the arteriolar level that may drain into the cardiac cavity (arteriosinusoidal vessels) and venous communications (thebesian veins) to the right atrium. These small vessels do not steal significant nutrient flow and do not constitute fistulous connections. Fistulae usually are large (>250 mm) and dilated or ectatic, and they tend to enlarge over time. Often, the limits of what constitutes a fistula and what constitutes a normal vessel are debated.
Most fistulae arise from the right coronary artery (60%) and terminate in the right side of the heart (90%). The most frequent sites of termination, in descending order, are the right ventricle, right atrium, coronary sinus, and pulmonary vasculature. Coronary fistula communications may appear in the context of other congenital cardiac anomalies, most frequently in critical pulmonary stenosis or atresia with an intact interventricular septum and in pulmonary artery branch stenosis, coarctation of the aorta, and aortic atresia. In the setting of cardiac outflow obstruction, the term coronary-sinusoidal connections is used. Although most often congenital, a coronary fistula rarely may arise as a consequence of surgical resection of obstructing right ventricular muscle bundles (as in tetralogy of Fallot), endomyocardial biopsy, or penetrating or blunt trauma.
Embryology
CAF are thought to arise as a persistence of sinusoidal connections between the lumens of the primitive tubular heart that supply myocardial blood flow in the early embryologic period. CAF occur in the absence of obstruction. Another explanation may be faulty development of the distal branches of the coronary artery rectiform vascular network.
When these channels persist in association with outflow obstruction (eg, pulmonary atresia), they are a variant form of fistulae termed coronary-sinusoidal connections. Associated syndromes most often associated with coronary-sinusoidal connections include pulmonary atresia or stenosis with an intact ventricular septum. In this setting, epicardial coronary blood may flow to and fro during the cardiac cycle.
In systole, right ventricular flow decompresses via coronary-sinusoidal connections to the aorta in a reverse direction, while in diastole, the aorta perfuses the coronary artery in a normal antegrade fashion. This contrasts with coronary arteriovenous fistulae in the absence of outflow obstruction, in which coronary steal is the primary pathophysiologic problem. In pulmonary atresia and coronary-sinusoidal connections, myocardial ischemia, necrosis, fibrosis, and systemic desaturation may occur. Areas of coronary stenosis and/or interruption of the coronary system may complicate this abnormality. No associated noncardiac conditions exist.
Frequency
United States
CAF accounts for 0.2-0.4% of congenital cardiac anomalies. Approximately 50% of pediatric coronary vasculature anomalies are CAFs.
Mortality/Morbidity
- Fistula-related complications are present in 11% of patients younger than 20 years and in 35% of patients older than 20 years. Larger fistulae progressively enlarge over time, and complications, such as congestive heart failure (CHF), myocardial infarction, arrhythmias, infectious endocarditis, aneurysm formation, rupture, and death, are more likely to arise in older patients. Spontaneous closure has been rarely reported.
- Surgery-related complications: The mortality rate related to surgical repair of CAF typically ranges from 0-4%. Variations that may increase surgical risk include the presence of giant aneurysms and a right coronary artery–to–left ventricle fistula. Complications of surgery include myocardial ischemia and/or infarction (reported in 3% of patients) and CAF recurrence (4% of patients).
Race
No race predilection exists.
Sex
No sex predilection exists.
Age
CAF may present in patients at any age but is usually suspected early in childhood when a murmur is detected in an asymptomatic child. Older children with murmurs may present with symptoms of coronary insufficiency. In a multicenter review, appreciably more problems related to operative risks and postoperative complications occurred after the age of 20 years (Liberthson RR, 1979).
History
Most children with coronary fistulae are asymptomatic, and continuous murmur may be audible on routine examinations. In older patients, symptoms may include the following:
- Dyspnea on exertion
- Angina
- Fatigue
- Palpitations
- Patients with large fistulae may present with high-output CHF, although rarely.
Physical
Most patients are asymptomatic, and CAF is suspected following detection of a continuous murmur on routine examination. On clinical examination, the murmur is suggestive of patent ductus arteriosus (PDA) but is heard lower on the sternal border than usual; thus, the location often is atypical for a PDA. In addition, the murmur may have an unusual diastolic accentuation, and the continuous murmur of a CAF often peaks in mid-to-late diastole, which is uncharacteristic of the systolic accentuation in a patient with PDA. If the fistula connects to the left ventricle, only an early diastolic murmur may be heard, as little coronary flow is evident during the period of systole. Some patients with fistulae with a large shunt may present with signs of CHF and angina.
Causes
- Most CAF are congenital and may be found in patients with structurally normal hearts. A specific variant form of CAFs (coronary-sinusoidal connection) that occur in association with congenital heart disease arise most often in association with severe right or left ventricular outflow obstruction, such as pulmonary atresia with intact ventricular septum or aortic atresia with hypoplastic left heart syndrome. In outflow obstructions, the fistula serve to decompresses the ventricle in a retrograde flow fashion.
- Rarely, acquired forms of CAF may occur as a result of septal myectomy in association with hypertrophic cardiomyopathy, muscle bundle resection in operative repair of tetralogy of Fallot, as a complication of radiofrequency ablation of accessory pathways, penetrating or nonpenetrating trauma, endomyocardial biopsy, permanent pacemaker implantation, or as a complication of coronary arterial procedures.
Arteriovenous Fistulae, Pulmonary
Patent Ductus Arteriosus
Sinus of Valsalva Aneurysm
Other Problems to be Considered
Ruptured sinus of Valsalva aneurysm
Ventricular septal defect with aortic insufficiency
Venous hums
Intrathoracic systemic fistulae
Imaging Studies
- Echocardiogram: Two-dimensional echocardiograms may reveal left atrial and left ventricular enlargement as a consequence of significant shunt flow or decreased regional or global dysfunction as a consequence of myocardial ischemia. The feeding coronary artery often appears enlarged, ectatic, and tortuous. High-volume flow may be detected by color-flow imaging at the origin or along the length of the vessel. Carefully seek the site of drainage; often, it is evident as a disturbed flow signal, most frequently within the right ventricle.
- Cardiac catheterization remains the modality of choice for defining coronary artery patterns of structure and flow. Most frequently, intracardiac pressures are normal and shunt flow is modest. Aortography (see Image 1) or selective coronary arteriography (see Image 2) supplies the information required to manage the condition. In addition, therapeutic embolization using occlusive coils or devices may be performed via catheterization.
- Reliable, complete, noninvasive 3-dimensional imaging of the coronary vasculature is advantageous. Traditionally, MRI has been a good alternative for imaging proximal coronary abnormalities, and newer imaging sequences have provided improved anatomic imaging as well as indices of coronary flow and function. Spatial resolution is often limiting, and the distal course and insertion of the fistulous connection may not be well imaged.
- Recently, multidetector row computed tomography (MDCT) cardiac imaging has provided excellent distal coronary artery and side branch imaging. Imaging of an entire 3-dimensional volume and the heart can be acquired within 20 seconds, with better temporal and spatial resolution than MR. Several authors now advocate consideration of MDCT in imaging of coronary anomalies (see Image 3).
- Stress thallium studies may be used to document areas of myocardial ischemia before and after operative repair.
Other Tests
- ECG may demonstrate the effects of volume load on the left ventricle and left atrium. Rarely, in the presence of coronary steal, ischemic changes and/or arrhythmias may be evident.
- Chest radiograph findings are generally normal, except in the presence of significant shunt flow, at which time cardiomegaly may be evident.
Medical Care
In childhood, most patients are asymptomatic; however, some patients may present with symptoms of dyspnea on exertion, increased fatigability, and, possibly, signs of high-output CHF. Rarely, patients may present with angina, palpitations, or signs of exercise-related coronary insufficiency. Direct medical treatment for symptomatic relief can be used until investigations and operative repair can be performed. Spontaneous closure is rare but may occur in small fistulae. Small fistulous connections in the asymptomatic patient may be monitored. Most lesions enlarge progressively and warrant operative repair, either by transcatheter or surgical techniques. Provide endocarditis prophylaxis in all patients. Diagnostic cardiac catheterization should be performed initially with or without additional therapeutic intervention. Initial diagnostic catheterization should both define hemodynamic significance of the lesion and provide detailed angiographic assessment of the anatomy of the abnormality, in particular, the origin, course, regional narrowings, and the nature of the insertion. Procedural options can be optimized by careful identification of the number of fistulous connections, nature of feeding vessel or vessels, sites of drainage, and quantification of myocardium at risk for injury or loss. The goal of treatment is the obliteration of fistula, while preserving normal coronary blood flow. Therapeutic transcatheter embolization is described as follows:
- Indications: In view of the natural progression in larger fistulae to dilate over time, with progressively increasing risk of thrombosis, endocarditis, or rupture, the general advice is to close all but the small fistulous connections. In borderline situations, provide close echocardiographic or angiographic follow-up imaging to identify enlargement of feeding vessel in asymptomatic patients. Patients with large fistulae, multiple openings, or significantly aneurysmal dilatation may not be optimal candidates for transcatheter closure.
- Technique
- Transcatheter embolization techniques using coils (see Image 4), bags, or other devices can be performed on an outpatient basis at the time of diagnostic studies or later, and may obviate the need for cardiac surgical intervention.
- Generally, the course of the fistulous tract is delineated angiographically, selectively catheterized, and wired along its entire length. A delivery catheter or sheath is then positioned antegradely or retrogradely along the stabilizing wire for delivery of a suitable occlusive coil or device. The occlusive device is positioned so as to minimize myocardial muscle loss or injury. Often multiple devices or coils may be required for effective occlusion.
- The transcatheter approach is, frequently, a fairly complicated intervention and requires an experienced operator and interventional specialist with expertise in both coronary arteriography and embolization techniques. Embolization often requires complicated catheter manipulation, as well as selection of various catheters and wires.
- Results: To date, the literature has primarily provided only case reports and reports of small series. Results have been comparable to surgery without associated morbidities of cardiopulmonary bypass and/or sternotomy.
Surgical Care
Cardiac surgical intervention is described as follows:
- Indications: Indications for surgical intervention are the same as in embolization (see above). Some fistulae are unsuitable for the transcatheter approach and preferably are addressed surgically. These CAFs may include fistulae with multiple connections, circuitous routes, and acute angulations that make catheter positioning difficult or impossible.
- Techniques: Surgical repair usually is approached via a median sternotomy and cardiopulmonary bypass. Identify the feeding vessel and delineate its course and site of insertion. Identify the site of presumed fistulous drainage prior to institution of the cardiopulmonary bypass. Transesophageal echocardiographic imaging has been very useful in assisting in the location of fistulous tract insertion. A typical procedure includes opening the chamber into which the fistula drains, identifying the fistula, and closing the site of drainage with a patch or suture. If the fistula enters the ventricle or if the feeding vessel is large, the coronary artery is opened, and the opening to the fistula is closed with a running suture. The arteriotomy is closed. Large aneurysms may require excision. Rarely, when the fistula is an end artery, it may be ligated with or without bypass.
Activity
Most patients should anticipate no restrictions on activity; however, patients who wish to compete in athletic endeavors should undergo stress testing and may be at marginally increased risk for dysrhythmias and sudden death.
The primary therapeutic approach to this anatomic abnormality is interventional catheterization or surgery. Although medical therapy is seldom indicated, patients may require symptomatic treatment of CHF and/or coronary insufficiency until definitive treatment can be performed.
Antibiotics for endocarditis prophylaxis are required before performing procedures that may cause bacteremia. For more information, see Antibiotic Prophylactic Regimens for Endocarditis.
Further Outpatient Care
- Provide follow-up care after hospital discharge to check for evidence of ischemia or recurrence of fistulae. Individuals who have undergone coronary surgical interventions and, particularly, patients who have sustained cardiac muscle loss should have ongoing cardiac follow-up monitoring that may include stress studies and repeat angiography as needed.
- Patients treated surgically and with transcatheter techniques should receive maintenance doses of antiplatelet agents and, perhaps, an anticoagulant regime for the first 6 months postoperatively, until the operative surface has undergone endothelialization. Patients with persisting aneurysmal dilatations may benefit from prolonged antiplatelet agents.
- Patients remain at risk for development of endocarditis until the flow is stopped and should receive antibiotic prophylaxis for any dental, gastrointestinal tract, and urologic procedures.
Complications
- Complications of surgery include myocardial ischemia and/or infarction (reported in 3% of patients) and recurrence of the fistula (4% of patients).
- Major complications associated with transcatheter embolization relate to manipulation of stabilizing catheters and wires in the coronary vasculature and may include coronary artery spasm, ventricular dysrhythmias, and perforation. Inappropriate positioning or proximal extension of occlusive coils or devices may result in obstruction of side branches and muscle loss. Intimal dissection of the coronary artery or thrombosis also may occur. However, morbidity and mortality rates generally are considered to be low.
Prognosis
- Recent results of both transcatheter and surgical approaches indicate a good prognosis. Approximately 4% of patients may require additional surgery for recurrence. Life expectancy is considered normal. However, risk of degenerative atherosclerotic disease may be higher if ectasia and dilatation of the coronary artery persist or progress. In young surgical patients, anticipate the involution of the dilated segment of the feeding vessel; this is not the case in adults.
Medical/Legal Pitfalls
- Failure to make the diagnosis of CAF
- Failure to realize that since spontaneous closure occurs in 23% of small fistulae, primarily those arising from the left coronary system, conservative management may be appropriate in some patients
- Failure to advise patients that they should receive appropriate antibiotics for any dental, oropharyngeal, gastrointestinal tract, or urologic surgical procedures
| Media file 1:
Coronary artery fistula. Selective LCA injection demonstrating a markedly enlarged left main (*) with normal size circumflex (CX) and left anterior descending (LAD) branches. The fistula continues across the RV free wall to the atrioventricular groove where it terminates at the crux of the heart in the right atrium (straight arrow) (Reproduced from Congenital Heart Disease, Textbook of Angiocardiography, Freedom RF, et al.) |
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Media type: X-RAY
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| Media file 2:
Retrograde aortic root injection, dilated left main (LCA) and circumflex (CX) vessels with the fistulous connection to the RV (arrow) (Reproduced from Congenital Heart Disease, Textbook of Angiocardiography, Freedom RF, et al). |
 | View Full Size Image | |
Media type: X-RAY
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| Media file 3:
Three-dimensional multidetector row computed tomographic image showing a circumflex artery fistula. The left main stem is greatly dilated (arrow) and a dilated, tortuous circumflex artery becomes aneurysmal (An) before draining into the coronary sinus. Note also the left anterior descending (LAD) branches arising from this dilated vessel (arrowhead). Image courtesy of BMJ Publishing Group (Reproduced from Manghat, 2005). |
 | View Full Size Image | |
Media type: Image
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| Media file 4:
Selective left coronary angiogram immediately after transcatheter coil occlusion of the circumflex coronary fistula (4 7- x 70-mm target coils). A tiny residual leak and the proximal circumflex coronary dilatation are shown. Image courtesy of Texas Heart Institute (Reproduced from McMahon, 2001). |
 | View Full Size Image | |
Media type: X-RAY
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Coronary Artery Fistula excerpt Article Last Updated: Jul 17, 2006
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