Treatment of Large Arteriovenous Malformation in Right Lower Limb
A 10-year-old boy (height, 120 cm; weight, 20 kg) presented with an 8-year history of arteriovenous malformation (AVM) involving the right lower limb. He had been started on sclerotherapy 4 years earlier because of leg length discrepancy causing gait disturbance. However, this treatment was stopped because there was no remarkable improvement. A year before presentation, the AVM had undergone rapid expansion causing significant pain and high-output cardiac failure. Therefore, an amputation of the affected lower limb was recommended at the other hospital.\nOn admission to Kyungpook National University Hospital, an examination revealed that AVM with soft tissue hypertrophy had spread all over the right leg (). A chest X-ray showed marked cardiomegaly with increased pulmonary vascularities (). Electrocardiography showed normal sinus rhythm with right ventricular hypertrophy. Two-dimensional echocardiography showed an enlarged right atrium, right ventricle, and left ventricle, but relatively good left ventricular contractility. The pulmonary artery was also enlarged, but there was no pulmonary edema. Computed tomographic (CT) angiography of the right lower extremity revealed extensive AVM with feeding arteries from the branches of the right profunda femoris and superficial femoral arteries. The venous drainage was through the superficial femoral and deep femoral veins, and there was a marked dilatation of the pelvic vein and inferior vena cava (). The blood investigations were found to be normal.\nOne week before surgery, the patient was scheduled to receive preoperative selective embolization to reduce the size of the AVM and minimize the risk of uncontrolled intraoperative bleeding. For embolization, the radiologist performed catheterization through the left common femoral artery and installed a tourniquet over the right proximal thigh. Soon after, remarkable bradycardia developed due to a baroreceptor reflex-induced abrupt increase in the systemic vascular resistance (SVR), and this procedure was cancelled. After a thorough discussion with the plastic surgeons, orthopedic surgeons, and vascular surgeons, right hip disarticulation was considered to be the best option for improving the patient's quality of life. It was anticipated that the large feeding vessel branches of the right profunda femoris artery, superficial femoral artery, and the large veins draining the limb would be difficult to control during a hip disarticulation. To minimize the chances of torrential hemorrhage, a disarticulation was planned under cardiopulmonary bypass.\nAfter anesthetic induction, an intra-arterial catheter 22G was inserted into the left radial artery to check the invasive arterial pressure and cardiac output by using an arterial pressure waveform-derived cardiac index sensor (FloTrac; Edward Lifesciences LLC, Irvine, CA, USA) and monitor (Vigileo, Edward Lifesciences LLC). Further, a central venous catheter was positioned into the left subclavian vein.\nAfter induction, the mean arterial pressure was maintained between 60 and 80 mmHg. The cardiac index (CI) and the central venous pressure (CVP) were recorded at 10 and 18, respectively, which were considered to be high.\nAfter heparinization, the right iliac artery was cannulated using an 18 French (Fr) cannula, and a 24 Fr venous cannula was placed through the right iliac vein. Partial cardiopulmonary bypass (CPB) was commenced at a flow rate of 1,200 mL/m2/min. The patient's body was maintained at a normal temperature, and the activated clotting time was greater than 400 seconds throughout the CPB. During a partial CPB, a continuous intravenous infusion of milrinone 0.5 µg/kg/min was used to improve the right ventricle function by decreasing the pulmonary vascular resistance. After the initiation of CPB, the CI and CVP were lowered to 2.5 and 3, respectively. The amputation was performed at the level of the proximal one-third of the right femur. The CPB time was 180 minutes. After heparin neutralization using protamine, the patient was weaned off of the bypass with 0.1 µg/kg/min of norepinephrine and 0.5 µg/kg/min of milrinone. Despite the use of CPB, the blood loss was extensive, and a transfusion of 8 units of packed red cells, 6 units of fresh frozen plasma, and 5 units of cryoprecipitate was required.\nHe was extubated on the following day. The postoperative period was uneventful, and he recovered fully with no neurologic deficit. A two-dimensional echocardiography, which was performed a week after surgery, showed a significantly smaller cardiac chamber. Two months after surgery, no residual lesion was observed in a CT angiography (), and a chest X-ray was unremarkable without cardiomegaly ().