Aortocaval fistula is a rare cause of clinically significant extracardiac left-to-right shunt. Up to 80 of cases described in the literature result from rupture of the aortic aneurysm, with 15 resulting from penetrating trauma.1 James Syme described this pathologic condition for the first time in 1831,2 Cooley conducted the first successful open-surgery repair in 1955,3 and the first stent-graft exclusion was made in 1998.4 We report a case of aortocaval fistula causing right-heart failure that was successfully treated with two-step endovascular embolization.
A 59-year-old male was admitted in our hospital for clinical evaluation and diagnostics. He had experienced symptoms of isolated right-sided heart failure for the last 10 yearsmainly dyspnea and fatigue during common physical activity and edema in the lower extremities. He also reported symptoms of pulsating abdominal formation over the past few years and had spontaneous audible pulsatile bruit around his body. His reported medical history was remarkable with right nephrectomy 25 years earlier due to benign tumor formation as well as controlled arterial hypertension and permanent atrial fibrillation.
During clinical examination, we observed a large palpable periumbilical abdominal formation, hepatomegaly, and pretibial edema. There was also an extremely loud abdominal systolicdiastolic murmur with maximum intensity at the right abdominal quadrant. An electrocardiogram showed normofrequent atrial fibrillation with an incomplete right bundle branch block and no repolarization abnormalities. Transthoracic echocardiography revealed normal left ventricular dimensions and left ventricular ejection fraction (62), biatrial dilatation more pronounced on the right side (left atrial area 28 cm2, right atrial area 35 cm2), and right ventricular dilatation and hypertrophy (basal diameter 51 mm, free wall thickness 8 mm). He had light mitral regurgitation and severe tricuspid regurgitation with an estimated right ventricular systolic pressure of 90 mm Hg. His inferior vena cava was extremely dilated (62 mm) in the whole abdominal segment, with Doppler characteristics of artery-like blood flow.
Contrast-enhanced CT aortography revealed a missing right kidney and an enlarged remnant of the right renal artery with an s-shaped course in the axial plan. There was also communication between the right renal artery and inferior vena cava (IVC). The IVC had a maximal width of 72 mm with dense contrasting of the vein in the arterial phase of the study and a high-flow left-to-right shunt (Figure 1).
Our multidisciplinary cardiovascular team discussed various treatment strategies in this case. Classic open surgery was deemed inappropriate due to extremely high perioperative predictive mortality, mostly because of the bleeding risk. Endovascular stent graft implantation was discussed as n option but was not covered by the patient's healthcare insurance. Another option was coil embolization.
The first reported endovascular treatment was performed by Cekirge et al. on a patient with an aortocaval fistula after nephrectomy in 1996, just 2 years before the first stent graft exclusion procedure.5 Cekirge's team used 39 coils followed by injection of rapid polymerizing glue. Based on the literature, we discussed a stepwise approach to avoid a sudden interruption of the left-to-right shunt, which carries the risk of extreme acute hypotension because of the acute decrease in venous return.
As a first step, we implanted two devicesa left atrial appendage (LAA) and patent ductus arteriosus (PDA) occluder (Occlutech International, AB)in the ostium of the right renal artery (Figure 2). This caused a moderate decrease of the fistula's flow. On contrast CT performed the next day, migration of the ostial device was established, and high-flow arteriovenous (AV) communication was restored with no significant difference in IVC contrast during the arterial phase (Figure 3). The two devices were stuck on the thinnest and most tortuous part of the AV communication, which allowed us to use them during a second procedure as an anchor for initial basket formation and packaging with coils.
Control computed tomography angiography (CTA) a day after the first endovascular procedure showed dislodgment and distal migration of the previously implanted PDA occluder caused by the high flow into the fistula. Note in Figure 2 that the arterial phase contrasting of the IVC is restored.
During a second endovascular procedure that was performed 1 month later, 13 embolization Penumbra Ruby coils (Penumbra, Inc.) were implanted using the conglomerate LAA/PDA occluder as anchoring and stabilization to avoid distal migration of the first several coils used to build the initial basket (Figure 4). We have used a 6F catheter with right radial vascular access (which is much more anatomically appropriate due to the acute angle at the target vessel's origin), a 6F multipurpose guiding catheter, and a Trailblazer microcatheter (Medtronic) for super-selective cannulation of the AV communication.
At the end of the procedure, there was a significant reduction in blood flow (Figure 4) and a 2-fold drop in pulmonary artery pressure (from 92 mm Hg to 50 mm Hg). One month after the second procedure, an echocardiogram showed a reduction in IVC size and a further reduction in tricuspid regurgitation (Figure 5).
The 2-year follow-up was uneventful, with the patient showing a complete lack of symptoms and complete resolution of the murmur compared to his NYHA functional class III at baseline. On physical examination, the palpable formation and systolicdiastolic murmur were not detectable, and his tricuspid regurgitation had improved from severe to trace. We also observed a significant rop in estimated pulmonary artery pressure, from 92 mm Hg at baseline to 40 mm Hg. Pleural effusion was completely resolved. The control CTA (Figure 6) showed complete isolation of the aortocaval fistula with no contrast in the IVC during the arterial phase. All aortic branches except the right renal artery were patent, and IVC size was reduced by half.
Aortocaval fistula is a rare, life-threatening, pathologic condition. An iatrogenic cause is extremely uncommon, with only a handful of successfully treated cases found in a literature search. Although surgical repair has been performed successfully, it is still associated with a high mortality rate. However, in select patients, endovascular treatment is an acceptable alternative.
Despite the lack of treatment guidelines for aortocaval fistula, stent-graft implantation has the most published experience. Unfortunately, it has been associated with late endoleak in some cases. Like the Cekirge case described in the literature, stepwise embolization for a high-flow AV fistula is a viable and efficient option. The upper (radial) remote vascular approach can be considered as a method of choice for the majority of elective visceral and renal endovascular interventions because of the acute angle of arterial origin. The applied strategy has the advantages of being a low-risk, minimally invasive approach with no need for general anesthesia and a short hospital stay.
Peripheral iatrogenic AV communication is a rare cause of pulmonary hypertension and right-sided heart failure. Endovascular treatment has become an effective alternative for treating high-flow AV communications in select patients. In the case described, a two-stage embolization procedure using an initial anchor with big occluder devices and additional filling coils resulted in a safe and efficient treatment.