Coronary Artery Fistula: Management and Intermediate-Term Outcome after Transcatheter Coil Occlusion

Abstract

During the last 2 decades, transcatheter occlusion of coronary artery fistulae has developed into a safe and effective therapy for children. This procedure avoids the need for open surgical repair and the attendant complications of cardiopulmonary bypass and median sternotomy. The long-term outcome in patients after transcatheter occlusion remains unknown. We describe the intermediate-term progress of 4 such patients after coil occlusion of coronary artery fistulae. Persistent coronary artery dilatation was present in all patients reviewed, as late as 4 years after occlusion.

Despite the relatively infrequent occurrence of coronary artery fistulae, they remain the most common hemodynamically significant congenital coronary anomaly. ¹ Surgical closure of coronary artery fistulae was initially reported in 1983 with low morbidity and mortality rates. ² Since then, investigators have reported successful transcatheter closure of congenital coronary artery fistulae in children using coils, ^3–7 detachable balloons, ^8–13 umbrellas, ¹⁴ poly-vinyl alcohol foam, ^15,16 and other occluding devices. ¹⁷ Transcatheter coil occlusion avoids the need for surgical intervention and cardiopulmonary bypass, as well as the attendant complications, and in many centers is the preferred therapeutic method. ¹⁸ Complications after coil occlusion are rare; coil embolization has been reported with little hemodynamic impact. ¹⁹ Little is known of the long-term outcome of the coronary artery after fistula coil occlusion. We describe management decisions and the intermediate-term follow-up of 4 patients after transcatheter coil occlusion of coronary artery fistulae.

Patient 1

An 18-month-old girl was referred to our institution for evaluation of a murmur. Physical examination revealed increased precordial activity, normal 1st and 2nd heart sounds, and a grade 3/6 continuous murmur, which was heard maximally at the left lower sternal border. The electrocardiogram was normal. The echocardiogram showed a dilated circumflex coronary artery with a fistula draining into the right ventricle. Cardiac catheterization and selective left coronary angiography revealed dilated left main and circumflex coronary arteries (each 9.5-mm diameter). The circumflex artery made four 180° curves in the atrioventricular groove and then entered the inferior aspect of the right ventricle beneath the posterior leaflet of the tricuspid valve (Fig. 1). The Qp:Qs = 1.5:1.0. Heparin (75 U/kg) was administered.

Fig. 1 Selective left coronary angiogram showing marked dilatation of the circumflex coronary artery, with a fistula arising from the distal circumflex coronary artery draining into the right ventricle directly beneath the tricuspid valve septal leaflet.

A 5-F Judkins left coronary catheter was placed in the proximal left coronary artery, through which a Tracker-18 Mx catheter (Target Therapeutics/Boston Scientific Corp.; Fremont, Calif) and a Dasher wire were manipulated through the fistula into the right ventricle. A 7- × 70-mm helical Target coil was deployed into the fistula at its most distal portion, just proximal to the right ventricle. After placement of two 7- × 70-mm coils and one 5- × 40-mm coil, a tiny residual fistula remained (Fig. 2). Repeat catheterization was performed 2 months later with deployment of 10 Target coils (4 × 40 mm), resulting in a minuscule residual leak. After coil occlusion, selective coronary angiography indicated improved filling of the left coronary and circumflex arteries. Post-catheterization cardiovascular examination was normal. Three years after coil implantation, cardiac catheterization and selective coronary angiography confirmed persistent circumflex dilatation (8.5 mm) despite complete fistula occlusion (Fig. 3). The patient remained asymptomatic 4 years after coronary artery fistula occlusion. Low-dose aspirin therapy was begun after the follow-up catheterization because of persistent coronary artery dilatation.

Fig. 2 Selective left coronary angiogram immediately after transcatheter coil occlusion of the circumflex coronary fistula (four 7- × 70-mm Target coils). A tiny residual leak and the proximal circumflex coronary dilatation are shown.

Fig. 3 Repeat selective left coronary angiogram 3 years after coil occlusion shows no residual fistula leak but persistent circumflex coronary artery dilatation, measuring up to 8.5 mm in diameter.

Patient 2

A 2-year-old boy was referred for evaluation of a murmur. Physical examination revealed an active precordium, bounding pulses, and a 3/6 continuous murmur heard throughout the right precordium. The electrocardiogram was normal. Transthoracic echocardiography showed a markedly dilated proximal right coronary artery with a dilated branch coursing posteriorly through the right atrium. Selective coronary angiography also showed a markedly dilated right coronary artery (8.8 mm in diameter). The artery supplied a large fistula (20 mm in diameter) located on the atrial septum. The fistula tapered to 6 mm and entered the posterior aspect of the right atrium just inferior to the entrance of the superior vena cava. It tapered to 3.9 mm as it entered the right atrium. Heparin (75 U/kg) was administered.

A 5-F Judkins right coronary catheter was placed in the right coronary artery just proximal to the fistula entry point into the right atrium. Two Gianturco coils (0.038″−5 cm−5 mm; Cook, Inc.; Bloomington, Ind) were implanted near the fistula entrance into the right atrium. After the procedure, angiography showed complete fistula occlusion. Repeat catheterization 18 months later revealed a markedly dilated proximal right coronary artery (8.8 mm) that narrowed to a normal caliber 2 cm from the sinus. The proximal coronary artery fistula was patent, with a diameter of 5.2 mm on its course along the atrial septum. The middle segment of the fistula remained aneurysmal (18-mm diameter). Distal to the aneurysmal dilatation, the fistula was completely occluded.

At the follow-up evaluation 3 years after coil occlusion, the boy was asymptomatic. Echocardiography indicated persistent proximal right coronary dilatation (6.6 to 7.7 mm in diameter) with normal left ventricular end-diastolic dimensions. He remains on low-dose aspirin therapy (81 mg/day).

Patient 3

A 2-year-old boy was referred for evaluation of a murmur. Transthoracic echocardiography showed moderate dilatation of the left main and anterior descending coronary arteries (3.8- and 3.5-mm diameters, respectively), with a fistula draining into the right ventricle. At 4 years of age, the boy underwent cardiac catheterization. Selective left coronary angiography showed moderate dilatation of the left main and left anterior descending coronary arteries (3.8 mm). The left anterior descending coronary artery coursed to the apex of the heart; in the posterior interventricular groove, it ended in a fistulous connection to the right ventricle. The left anterior descending coronary artery was tortuous; there was a stenotic segment in the mid-portion of the fistula 2 cm before the vessel entered the right ventricle. The Qp:Qs = 1.3:1.0.

The distal left coronary artery was accessed with a Judkins left coronary catheter, which was exchanged over a Microvena wire (Microvena Corp.; White Bear Lake, Minn) for a 4-F snare catheter. A Gianturco embolization coil (0.038″−5 cm−5 mm) was delivered through the snare catheter and implanted at the distal end of the fistula. Angiography revealed a small fistula leak; therefore, a 2nd Gianturco coil was implanted in the distal fistula segment. Post-occlusion angiography showed no residual leak but did indicate minimal filling of the fistulous tract from a 2nd, much smaller vessel, which originated in the mid-portion of the left anterior descending coronary artery. The procedure was uncomplicated.

Six months after coil occlusion, a follow-up echocardiogram revealed persistent left main coronary and left anterior descending coronary artery dilatation (3-mm diameter) with a persistent small fistulous connection arising from the mid-portion of the left anterior descending coronary artery. Low-dose daily aspirin therapy (81 mg/day) was begun after echocardiography demonstrated coronary artery dilatation.

Patient 4

A 3-year old boy presented for evaluation of a murmur. Physical examination revealed normal pulses, a quiet precordium, and a 2/6 low-frequency continuous murmur. The electrocardiogram indicated left ventricular hypertrophy. The echocardiogram showed a markedly dilated right coronary artery (8 mm in diameter), which coursed along the right atrioventricular groove and drained posteriorly into the right ventricle below the tricuspid valve. At catheterization, the Qp:Qs = 1.4:1.0. Selective right coronary angiography revealed a fusiform dilatation of the right coronary artery (8 mm) to the level of a large saccular aneurysm.

A 5-F coil catheter (Cook, Inc.) was used to implant twenty 0.038″ coils (four 5 cm−5 mm, eight 12 cm−10 mm, and eight 8 cm−5 mm) into the saccular aspect of the fistula. After implantation, angiography revealed a substantial reduction in flow through the fistula with a small residual leak, and no obstruction of flow in the posterior descending coronary artery. Over the next 48 hours, the patient developed hemolysis. Echocardiography after the catheterization showed a persistent shunt with multiple exit points. The hemolysis resolved after 6 months.

Twelve months later, a persistent fistula was found. Surgical occlusion was performed, because further coil implantation was not deemed feasible without compromising myocardial perfusion.

One year after surgery, the patient was asymptomatic. An echocardiogram indicated no residual fistula leak. The right coronary artery, however, remained dilated to a diameter of 4.3 mm. Low-dose aspirin (81 mg/day) was started.

Discussion

Although coronary artery fistulae are a relatively rare entity, they may give rise to such complications as cardiac failure, ischemia, thrombosis, arrhythmia, endocarditis, and even rupture. ^20–26 Surgical closure has been reported, either by external ligation of the fistula or by internal patching of the orifice. ²⁷ However, surgery entails the risks attendant upon cardiopulmonary bypass and median sternotomy. ^28,29

The 1st successful fistula occlusion was reported by Reidy and colleagues ¹² in 1983. Since then, transcatheter coil occlusion of coronary artery fistulae in children has evolved as the preferred therapy. Mavroudis and coauthors ³⁰ recommend elective coil occlusion in patients who satisfy the following criteria: absence of multiple fistulae, a single narrow drainage site, absence of large branch vessels, and safe accessibility to the coronary artery supplying the fistula. Although successful fistula occlusion has been reported with inflatable balloons, ^8–13 polyvinyl alcohol foam, ^15,16 and umbrellas, ¹⁴ the use of implantable coils is currently considered the best method, ¹⁸ due to improved control and delivery techniques. The risks of transcatheter coil occlusion are low, and there have been no reports of death in children. One fatality in an adult patient has been reported. ³¹ In children who are asymptomatic, we perform catheterization when the femoral artery has grown enough to avoid complications. ³² Developments in catheter and coil technology have made it possible to use 4- or 5-F catheters safely in infants. In addition, the fistula may be entered from the right atrium or ventricle; generally, this requires placing a wire through the fistula from the coronary artery. ³³

Little has been reported about the intermediate- to long-term results following transcatheter closure of coronary artery fistulae in children. Immediately after occlusion, we perform chest radiography, electrocardiography, echocardiography, and Holter monitoring. We also evaluate patients at 2, 6, and 12 months after coil occlusion. We often perform Holter monitoring again at 12 months to evaluate the possibility of vascular compromise to the sinoatrial or atrioventricular node and associated rhythm disturbance. Echocardiography is an excellent method for evaluating ventricular dimensions, ventricular function, coronary artery dimensions, and fistula leakage. ³⁴ We obtain echocardiograms at 6, 12, and 24 months after coil occlusion, especially in infants who have moderate-to-severe coronary dilatation. Cardiac catheterization and selective coronary angiography may be performed 12 to 24 months after coil occlusion to evaluate coronary artery dimensions and fistula persistence, particularly in those children who have limited echocardiographic windows.

The persistence of fistula leakage after coil occlusion is problematic. Given the risk of bacterial endocarditis and the presence of a foreign body (the coil), we recommend repeat catheterization and coil occlusion after 3 to 6 months. Placement of additional coils appears to be efficacious in abolishing persistent fistula leaks. ³⁵

Following coronary artery fistula occlusion, several children have demonstrated persistent coronary artery dilatation as late as 4 years, which is the duration of our follow-up. These children pose a therapeutic dilemma. Should antiplatelet therapy or anticoagulation be prescribed? If so, what form and dosage are appropriate? We administer low-dose aspirin therapy (3 to 5 mg/kg per day) until coronary normalization occurs. Severe coronary artery dilatation (>10 mm) may warrant anticoagulation with warfarin, especially in patients with sluggish coronary flow, although there is little information available concerning the risk of coronary thrombosis in this group. We continue subacute bacterial endocarditis prophylaxis for at least 1 year after complete fistula occlusion and coronary artery normalization.

Conclusion

Transcatheter coil occlusion of coronary artery fistulae is a safe and effective procedure in children. We recommend that children undergo this procedure in centers where experienced anesthesiologists and excellent pediatric and intensive care facilities are available, in order to minimize complications and expedite recovery. The long-term patient outcome after fistula occlusion remains unknown, but intermediate-term results reveal persistent coronary artery dilatation in many of these patients. Therefore, patients who have undergone coil occlusion of coronary fistulae require close follow-up; and, in certain cases, the use of antiplatelet therapy or low-dose anticoagulation may be warranted.

Acknowledgment

We are grateful to Ms Donna Poole for her assistance in the preparation of this manuscript.