Iatrogenic Fistula between the Left Anterior Descending Coronary
Artery and Anterior Interventricular Vein following Stenting

Coronary artery fistulae are uncommon vascular anomalies. The incidence of these anomalies is low, ranging from 0.2 to 0.25%.¹ The fistulae frequently drain into one of the ventricles, the pulmonary arteries, the coronary sinus and the superior vena cava or pulmonary veins. The etiology of fistulae is mostly congenital,² however, fistulae may occur secondary to other conditions such as cardiac trauma,³ coronary angioplasty,^4–6 repeated endomyocardial biopsies after heart transplantation,⁷ and following aortic valve replacement.⁸

We report a case of an iatrogenic arteriovenous (AV) fistula between the left anterior descending coronary artery (LAD) and the anterior interventricular vein (AIV) that occurred after stenting of the LAD. To the best of our knowledge, this is the first case of iatrogenic AV fistula between the LAD and AIV that occurred following stenting of the LAD.

Case Report. A 61-year-old African- American male was admitted with an acute myocardial infraction. Electrocardiography demonstrated ST-segment elevation in the lateral leads and nonspecific ST-segment changes in the anterior leads. Coronary angiography demonstrated 100% occlusion of the left circumflex artery (LCx) and an 80% stenosis in the LAD. The patient underwent successful stenting of the left circumflex artery (LCx). Two days later, the patient developed recurrence of angina and was brought back to the cardiac catheterization laboratory. Repeat angiography demonstrated that the stent in the marginal branch was patent; percutaneous coronary intervention of the LAD and diagonal branch was attempted.

A Balanced Middle Weight (BMW) wire and a Whisper wire (Guidant Corp., Indianapolis, Indiana) were advanced and positioned in the LAD and diagonal branch, respectively. The LAD was predilated with a 2.5 x 20 mm balloon, and then intravascular ultrasound (IVUS) was performed using a 2.6 Fr40 MHz Atlantis catheter (Boston Scientific Corp., Natick, Massachusetts).

IVUS showed a high-grade, moderately fibrocalcific lesion. In addition, it was noted that the middle segment of the stenotic lesion in the LAD was attached to an unusually large anterior interventricular vein (AIV) (Figure 1). IVUS also demonstrated that the average proximal and distal reference diameters were 3.6 and 3.9 mm, respectively; the lesion length was 28 mm.

Subsequently, a 3.5 x 28 mm Taxus^® stent (Boston Scientific) was deployed. After stent deployment, a well-demarcated atriovenous (AV) fistula was noted in the mid-portion of the stent (Figure 2A). In order to seal off the fistula, the stent-balloon was advanced inside the stent, and several short balloon inflations were performed. Coronary angiography demonstrated that the fistula had sealed, but there was a persistent stump in the mid-portion of the stent (Figure 2B). In order to completely seal the stump, a 3.5 x 12 mm polytetrafluoroetylene (PTFE)-covered stent (Grafmaster, Abbott Vascular, Inc., Redwood City, California) was advanced and positioned in the mid-portion of previous stent and inflated to 16 atm. Subsequently, a 3.5 x 15 mm Quantum Mavrick balloon (Boston Scientific) was positioned inside the covered stent and inflated to 20 atm.

Repeat angiography demonstrated that the fistula was completely sealed. Final IVUS study confirmed that the covered stent had separated the LAD from the AIV; after saline injection, no evidence of the fistula was noted (Figure 3). The patient remained stable hemodynamically throughout the procedure. Echocardiography in the catheterization laboratory and 24 hours later showed no pericardial effusion. The patient remained stable and was discharged on the next day. Follow-up coronary angiography at 6 months demonstrated no evidence of recurrence of the fistula or restenosis.

Discussion

To the best of our knowledge, this is the first reported case of a LAD-to-AIV fistula formation following stenting of the LAD,which was treated successfully with a PTFE-covered stent. As it is shown in Figure 1, IVUS, prior to stent deployment, demonstrates a thin membrane separating the LAD from its adjacent AIV. In this context, it appeared that after expansion of the stent, a tear occurred in the membrane that led to the subsequent AV fistula. After insertion of a PTFE-covered stent, the covered stent separated the LAD from the AIV, resulting in closure of the fistula (Figure 3). Since we were concerned that the fistula as such could have led to ischemia as a result of steal phenomenon or possible stent thrombosis, we used a covered stent, which successfully sealed the AV fistula.

Oesterle et al⁹ reported percutaneous in situ venous arterialization- PICVA (percutaneous in situ coronary venous arterialization) with the use of a novel catheter-based system in a patient who had chronic total occlusion of the LAD. In this patient, a fistula was created between the LAD and AIV using a self-expanding connecter. Furthermore, Oesterle et al¹⁰ reported the phase 1 feasibility study of PICVA in 11 patients who had angina and had no option for either angioplasty or surgical revascularization. In their courageous study,¹⁰ the adjacent vein could not be identified in 6 patients; PICVA was successfully completed in 5 patients, however, 2 of the 5 patients had catastrophic complications and died within 48 hours of the procedure.

The AIV runs parallel to the LAD or crosses the artery. As shown in Figure 1, IVUS demonstrates that the LAD and AIV are attached to one another by a thin membrane at one point along the LAD. Consequently, we speculate that in the present case report, a fistula developed after stenting when the membrane was ruptured as a result of stent expansion. Our case may have a future therapeutic implication that a fistula may be created between the LAD and AIV at the crossing point by the use of IVUS. In contrast to the study of Oesterli et al,¹⁰ in which the fistula was induced in an area of the LAD where the LAD and AIV are parallel, our case report shows that the fistula was at the crossing point of the LAD and AIV. Thus, after localization of the proximity between the LAD and AIV by IVUS, a 3-dimensional guided TransAcces catheter (TransVascular, Inc., Menlo Park, California) can be advanced to the artery and oriented toward the AIV. After advancing the needle of the TransAccess catheter from the LAD to the AIV, a fistula can be created by advancing a 0.014 inch guidewire and an angioplasty balloon. The above technique would perhaps offer a therapeutic approach to patients with chronic total occlusion of the LAD who are not amenable to PCI or surgery.

There are a few published series of arteriovenous fistulae to the cardiac chambers or to the great cardiac vein that developed following PCI or aortic valve replacement. In this context, Leor et al⁴ reported a case of arteriovenous fistula from the LCx to the great cardiac vein after an attempted angioplasty of the LCx. The patient was initially treated medically. However, shortly after discharge, the patient presented with symptoms of congestive heart failure, which did not respond to medical therapy; repeat angiography revealed that the fistula had increased in size and the patient ultimately underwent surgery. Korpas et al⁵ described a fistula between the LAD and the right ventricle (RV) after stenting of a chronic total occlusion of the LAD. Since the patient was hemodynamically stable, medical therapy was continued; angiography after 6 months showed evidence of in-stent restenosis and disappearance of the fistula. In this case, it appeared that oversizing of the stent was a contributing factor to the development of a fistula. Similarly, Chen et al⁶ described a case of perforation of the LAD after rotational atherectomy and stent implantation, leading to both cardiac tamponade and a fistula to the RV. During surgery, it was noted that the patient had also succumbed to free LV wall rupture; despite closure of the fistula and repair of the LV free wall rupture, the patient had a fatal outcome. Fistulae have also been described following surgery. Lopez-Candales et al⁷ reported a case of coronary artery-to-left ventricular fistula following aortic valve replacement; the patient was treated medically and remained stable during follow up.

Accumulating evidence suggests that as a result of slow progressive enlargement of a fistula or shunt augmentation, the majority of patients do become symptomatic with advancing age, usually during the fifth or sixth decade of life.¹¹ Complications of coronary fistulae include myocardial ischemia,¹² pulmonary artery hypertension¹³ and congestive heart failure owing to the left-to-right shunt.¹⁴ Other complications are rare, and include various arrhythmias,¹⁵ infectious endocarditis¹⁶ and cardiac tamponade secondary to the rupture of the fistula.¹⁵ The main indications for the treatment of coronary fistula include the occurrence of symptoms such as ischemia, heart failure or pulmonary hypertension.¹⁷ Controversy still exists concerning the closure of fistulae in asymptomatic patients.¹⁷ The methods of closure of fistulae include catheter-based interventions and surgery. Surgery has the inherent risk of preoperative mortality and myocardial infarction.¹⁷ An array of catheter-based interventions is available, including detachable balloons, stainless steel and platinum coils or different chemicals, such as pure alcohol.^18–20

In conclusion, this is the first described case report of an AV fistula between the LAD and AIV that occurred after stenting of the LAD, which was successfully sealed by deploying a covered stent. During follow up, the patient remained clinically stable, and no evidence of stent thrombosis or recurrence of fistula was noted. The pursuit of arterialization of the AIV, by virtue of the fistula creation between the LAD and AIV in patients with chronic total occlusion of the LAD that is not amenable to percutaneous or surgical revscularization, lies in the success of future investigations.

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