INTRODUCTION:Iatrogenic arteriovenous fistulae are a rare cause of pulmonary hypertension and high output heart failure. Adverse consequences of hemodynamic changes during operative repair have previously been reported, and uncertainty exists regarding long term effects on cardiac function following repair. We report a case of a young woman with a six-year history of pulmonary hypertension secondary to an arteriovenous (AV) fistula who underwent repair during an intensive care unit admission for severe high output heart failure.
CASE PRESENTATION:A 23 year old female presented with worsening shortness of breath. Her past medical history was significant for a laparoscopic appendectomy at age 17 complicated by mesenteric bleeding that resulted in laparotomy, multisystem organ failure, prolonged mechanical ventilation and placement of multiple central venous catheters. Over the following six years, she was noted to have pulmonary hypertension by echocardiograms and required repeated hospitalizations for heart failure. On her current admission, she was afebrile, tachycardic (100/min), hypertensive (159/73), and mildly tachypneic (18/min), with a loud murmur heard over her abdomen and right groin. Her chest x-ray showed bilateral infiltrates consistent with pulmonary edema. Initial echocardiography showed an estimated systolic pulmonary artery pressure of 88mmHg with a severely dilated right ventricle, enlarged right atrium, and preserved left ventricular size and function. She required intubation for increasing hypoxia and developed multiorgan failure. Doppler ultrasounds of both groin areas were negative for fistulae. However, concern for an AV fistula remained high. Therefore, the patient underwent angiography which demonstrated a large AV fistula from the right common iliac artery to the inferior vena cava. Right heart catheterization revealed a mean right atrial pressure of 15mmHg, a pulmonary artery pressure of 55/30mmHg (mean 38), and a wedge pressure of 18mmHg. Oximetry revealed a saturation of 91% in the inferior vena cava. She underwent stent graft placement of her right common iliac artery. This resulted in an immediate decrease in pulmonary arterial pressures, although wedge pressure and cardiac output did not change immediately. She did not decompensate clinically despite the sudden increase in afterload. Four hours postoperatively, the cardiac output decreased from 16 l/m to 11.8 l/m and the mean pulmonary artery pressure decreased to 29mmHg. Systemic vascular resistance increased from 174 to 400 d*s/cm5. On two month and twelve month follow-up appointments, her echocardiograms demonstrated complete resolution of the pulmonary hypertension and normalization of her right ventricular size and function.
DISCUSSIONS:Iatrogenic arteriovenous fistulae are a rare cause of pulmonary hypertension, and little is known regarding the short and long term cardiopulmonary consequences after repair. Concern exists regarding perioperative management of hemodynamic changes during closure of massive fistulae, as the sudden increase in left ventricular afterload can lead to acute cardiac decompensation. It is thought that the compensatory sustained volume overload and high cardiac output over time can lead to irreversible cardiac hypertrophy and ventricular dilatation. Furthermore, animal studies have suggested that pulmonary arterial remodeling occurs following creation of a systemic arteriovenous fistula, leading to flowinduced pulmonary hypertension. In our case, despite six years of documented pulmonary hypertension and multiple admissions for volume overload culminating in an episode of severe intractable heart failure, repair of a massive AV fistula did not lead to intraoperative decompensation. Long term follow-up revealed normalization of pulmonary pressures and ventricular size, indicating reversibility of the cardiopulmonary changes.
CONCLUSION:Iatrogenic systemic AV fistulae are a rare cause of secondary pulmonary hypertension and high output heart failure. Repair of massive AV fistulae may be well tolerated intraoperatively despite an acute afterload increase. A longstanding history should not preclude repair since symptomatic pulmonary hypertension or high output heart failure may be completely reversible.
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