Managing Post-CABG iatrogenic aortocoronary arteriovenous fistula- A case report

Even though they are uncommon, problems after heart surgery often go undetected for a while and are only identified after a thorough examination and a high degree of suspicion. One such side effect occurs when a coronary graft is inadvertently anastomosed to an epicardial vein rather than the planned arterial target. This condition is known as an iatrogenic aortocoronary arteriovenous fistula (ACAVF). To properly treat a patient for repeat heart surgery, a complete knowledge of the aberrant anatomy is essential. Recently published case report described a case of re-doing cardiac surgery for an iatrogenic ACAVF that was managed intraoperatively and validated perioperatively using numerous modalities.

The mid ascending aorta of a 74-year-old lady was found to have a worrying limited rupture as opposed to a localised dissection that extended into the proximal arch. Less than a year before, she had coronary artery bypass grafting (CABG) performed with a pedicled left internal mammary artery (LIMA) to the left anterior descending (LAD) and a reverse saphenous vein graft (SVG) to a circumflex branch. A drug-eluting stent had been implanted in the proximal circumflex before to the surgical revascularization, however the ostial left main lesion could not be treated with catheter-based techniques. She had a routine early postoperative course after CABG and was asymptomatic without exertional dyspnea at her three-month follow-up, when a continuous murmur was discovered on physical examination for the first time. The aortic pseudoaneurysm/localized dissection was then seen on a computed tomography angiography (CTA) that was taken near the origin of the SVG. She was then recommended to our facility for surgical care. An echocardiography performed prior to surgery revealed healthy biventricular function without valvopathy. In addition to chronic ostial left main stenosis, a nearly occluded LIMA to the LAD, and a broadly patent circumflex system, preoperative coronary angiography revealed a left to right shunt consistent with an aortic to coronary sinus saphenous vein graft . The patient went into surgery to treat the anomalous ascending aorta and the lingering ostial left coronary stenosis. A Swan-Ganz catheter was inserted for monitoring while radial and femoral arterial lines were put on the patient during an induction under general anaesthesia. A considerable reduction in pulsatility and turbulent flow was seen in the coronary sinus during real-time transesophageal echocardiography after the vein graft was clamped. When a retrograde cardioplegia catheter was inserted into the coronary sinus and transduced, it once again showed strong pulsatility and pressures that were very close to those of the aorta. The coronary sinus catheter was also exposed to air pressure and visually inspected. Bright red, pulsating arterial blood was seen ejecting from the catheter into the surgical area when the vein graft was unclamped; however, when the vein graft was occluded, the flow was greatly reduced and the blood colour darkened to seem venous.

An old SVG graft was removed during surgery close to the distal anastomosis to a distal cardiac vein, and a fresh SVG graft was then implanted to the mid LAD. Additionally, the sino-tubular junction level was reached with the proximal debridement of the aberrant proximal ascending aorta. The remaining distal ascending aorta and the proximal arch were removed, and they were subsequently replaced with a 30 mm Dacron graft, with flat-line EEG having been seen for more than 5 minutes at a temperature of about 20 degrees C. While the LIMA to LAD graft was kept in situ in spite of indications of negligible flows, the SVG to the LAD was attached closely to the ascending Dacron graft.

Less than 40 cases of iatrogenic aortocoronary arteriovenous fistulae after coronary artery bypass grafting have been documented. This happens when a graft is inadvertently anastomosed to an epicardial vein rather than its target artery, most often to the great cardiac vein. This case demonstrates the need of careful preoperative imaging and planning prior to surgical intervention as well as the advantages of using a variety of investigative approaches to support an unusual discovery. After surgical intervention, understanding the patient's coronary architecture might be crucial for a successful reoperation, particularly if there is an unexpected complication.

Reference –

Klompas AM, Kawajiri H, Sinak LJ, Pochettino A. Resisting arrest: Perioperative confirmation and management of an iatrogenic aortocoronary arteriovenous fistula after coronary artery bypass grafting for redo cardiac surgery. Ann Card Anaesth 2023;26:83-5