Coronary-Pulmonary Artery Fistulae

Keywords: sinus node artery; atrioventricular node artery; variation; common origin.
Abbreviations: RCA – right coronary artery, RAO – right anterior oblique, LAO – left anterior oblique.

Abstract
Coronary artery fistulae are rare but bicoronary-pulmonary artery fistulae are even rarer. We describe a 64yr old male who presented with retinal artery occlusion and chest pain. Trans esophageal echocardiography demonstrated an intra-atrial septal aneurysm and a small patent foramen ovale. His stress test was positive for ischemia with 1-2mm ST depression in the inferolateral leads. Coronary angiography revealed bilateral coronary –pulmonary artery fistulae arising from RCA and L CX, and no obstructive coronary artery disease.

Introduction
Coronary artery fistulae were first described by Krause in 1865, and are present in 1 of 50,000 live births (.002% of the general population). They may be associated with other congenital heart disease in 20-45% or may be isolated in 55-86% of cases (1). Coronary-pulmonary fistulae account for 15% of all coronary-cardiac fistulae. Bicoronary-pulmonary artery fistulae are rare with an incidence of .004% to .01% (2).

We present a patient with angina, an intra-atrial septal aneurysm with a PFO and bicoronary-pulmonary artery fistulae without obstructive coronary artery disease.

Case Report
The patient is a 64 yr. old male with a past medical history significant for asthma, hyperlipidemia and GERD who presented with retinal artery occlusion. He subsequently underwent a TEE to evaluate the presence of an intracardia source of emboli. The TEE revealed intra-atrial septal aneurysm, small PFO, mild MR/TR/AI and an EF of 65%. Upon further evaluation, he reported having had exertional dyspnea and chest pain.

The patient had a treadmill stress test, exercising for 11 minutes without symptoms; but developed 1-2-mm horizontal ST depressions in the inferolateral leads at peak exercise (Fig 1 & 2).

It was decided to follow the patient clinically without any intervention on anti-platelet agents.

He was doing well clinically for nine months until he was hiking in Canada when he developed SOB and chest pain. While in Canada he had went to a local ER where he had an EKG and cardiac enzymes, which were negative for myocardial ischemia; V/Q scan and dopplers were also done and were negative. When he returned to the US he had another stress test, exercising for 11 min 31 sec with SOB and chest pain; 5mm ST depressions in the inferior leads and 3mm ST depressions in lead V5 & V6 which persisted 7 minutes into recovery. It was decided to repeat the stress test with nuclear imaging, again the EKG portion of the stress test was positive, however nuclear imaging did not reveal perfusion abnormality and gated SPECT did not reveal any wall motion abnormality with an EF of 64%.

The patient subsequently had bilateral coronary angiography to assess the hemodynamic significance of his coronary fistulae. His Pulmonary artery pressure was 25/5 mm Hg, no -step up in arterial saturation was appreciated and a shunt fraction of 1.0.
Bilateral coronary –pulmonary artery fistulae were again seen without evidence of obstructive coronary artery disease.

Clinical follow up was again recommended.

Discussion
Coronary-pulmonary artery fistulae comprise half of all coronary artery anomalies and are the most hemodynamically significant lesions. Most common are single fistulae in 74-90%; multiple fistulae are present in 10.7-16% with fistulae originating from both coronaries in 4-18% of cases (3).

Multiple coronary-pulmonary artery fistulae have been reported, Gupte et al reported two patients. One patient had fistulae from RCA and LAD terminating into the main pulmonary artery without obstructive coronary artery disease; second patient had fistulae from all 3 coronary arteries and sinus venosus ASD that was repaired (4). Abhyankar et al reported a case of a patient with non-exertional chest pain with a normal nuclear stress test with 3 coronary artery fistulae arising from LAD, 2 from LCX and 2 from RCA, all of which drained into the main pulmonary artery, without concomitant coronary artery disease. The patient did not have corrective surgery and continued to atypical chest pain (5). Chin et al. presented a patient with acute inferior wall myocardial infarction and cardiac arrest with fistulae arising from the RCA and LAD draining into the main pulmonary artery and occlusive coronary artery disease (6).

Ashraf et al reported a case with biventricular failure and angina in a pt with coronary-pulmonary fistulae arising from LAD without obstructive coronary disease, severe MR with mitral valve prolapse (2). Chang et al reported three patients who had presented with chest pain and fistulae between the LAD and pulmonary artery. Two of the patients had concomitant coronary disease, one of which had another fistulae arising from LCX (7).

If there are no symptoms of ischemia due to coronary steal, indication for surgery will depend on the magnitude of the shunt (8). Patients without symptoms with a shunt less than 1.4:1 can be observed but some feel that even these fistulae should be ligated since the risk of operative intervention is low. Repair of fistulae with large left to right shunts should be done before the development of pulmonary hypertension in order to improve symptoms (2).

From the cases reviewed in the literature the patients without CAD had no evidence of ischemia to support coronary steal as the mechanism for chest pain in this patient population. Our patient had several positive stress tests for ischemia by EKG criteria however his nuclear scan showed no perfusion abnormality. It is possible that the inducible ischemia is subendocardial and diffuse.

Our patients’ symptoms worsened when he was climbing high altitudes in Canada; there may have been an increase in shunting because of the shift in the oxygen dissociation curve.