Resumen de Endovascular evaluation and treatment of intrahepatic portosystemic shunts in dogs: 100 cases (2001�2011)
Objective�To evaluate short- and long-term outcome following endovascular treatment of intrahepatic portosystemic shunts in dogs.
Design�Retrospective case series.
Animals�100 dogs.
Procedures�All patients had angiographic evaluation with or without endovascular shunt attenuation. The medical records were reviewed for pertinent data, complications, outcome, and survival time.
Results�95 dogs with congenital intrahepatic portosystemic shunts received 111 procedures (83% [79/95] had 1 treatment, and 17% [16/95] had > 1 treatment; 5 dogs had no treatment because of excessive portal venous pressure�central venous pressure gradients). Angiography identified 38 right, 33 left, and 19 central divisional single shunts (n = 90) and 10 complex or multiple shunts. Partial shunt attenuation was performed in 92 dogs by means of caval stent placement and insertion of thrombogenic coils within the shunt, and 3 had complete acute shunt occlusion. Major intraoperative complications (3/111 [3%]) included temporary severe portal hypertension in 2 dogs and gastrointestinal hemorrhage in 1 dog. Major postoperative (< 1 week after surgery) complications (14/111 [13%]) included seizures or hepatoencephalopathy (7/111 [6%]), cardiac arrest (2/111 [2%]), jugular site bleeding (2/111 [2%]), pneumonia (1/111 [1%]), suspected portal hypertension (1/111 [1%]), and acute death (1/111 [1%]). Median follow-up time was 958 days (range, 0 to 3,411 days). Median survival time for treated dogs was 2,204 days (range, 0 to 3,411 days). Outcome was considered excellent (57/86 [66%]) or fair (13/86 [15%]) in 70 of 86 (81%) treated dogs.
Conclusions and Clinical Relevance�Results suggested that endovascular treatment of intrahepatic shunts in dogs may result in lower morbidity and mortality rates, with similar success rates, compared with previously reported outcomes for open surgical procedures. Gastrointestinal ulceration was a common finding among this population of dogs, and lifelong gastroprotectant medications are now recommended.
Portosystemic shunts are vascular anomalies connecting the portal and systemic venous systems that result in varying degrees of biochemical and clinical abnormalities. The goal of surgery is to attenuate the abnormal vessel to restore or improve portal perfusion and ultimately maximize hepatic function. Unfortunately, only a minority of intrahepatic PSSs can be completely occluded acutely without resulting in life-threatening portal hypertension.1�10 These unfavorable circumstances have led to the development of a number of surgical techniques designed to provide progressive shunt attenuation that will ultimately restore portal perfusion yet minimize the risk of acute portal hypertension.3�6 Although animals with congenital extrahepatic PSSs can respond well to fairly uncomplicated progressive shunt attenuation performed surgically, IHPSSs are often much more difficult to isolate and attenuate surgically. Not surprisingly, surgical approaches for IHPSSs have been associated with complication rates as high as 77%,9 perioperative mortality rates up to 28%,4,7�9 and overall mortality rates as high as 64%.4,8�10 In addition, some techniques designed to achieve progressive attenuation have been shown to perform unpredictably, either resulting in premature vascular occlusion (and development of multiple acquired shunts) or ultimately not achieving complete occlusion.1,11�13 A recent retrospective study12 found similar complication rates between partial suture ligation and ameroid constrictor placement for left divisional IHPSSs and better outcomes with the partial ligation technique, even though, ultimately, complete shunt attenuation was unlikely. Cellophane banding has been demonstrated to provide progressive vascular attenuation; however, it remains unclear whether complete attenuation is ultimately achievable in patients with larger IHPSSs, and the use of cellophane in patients with IHPSSs has a reported 27% mortality rate and 55% complication rate.4 Hydraulic occluders were demonstrated to achieve predictable, controlled vascular occlusion, and if portal hypertension developed, the occlusion could theoretically be reduced relatively simply with access via the subcutaneous injection port and withdrawal of saline.5 There were a number of technical complications encountered with this technique, but these were considered minor by the authors and reportedly addressed.5 This technique has similar drawbacks in that substantial shunt dissection and isolation are still required owing to the relatively large device size.5,14 In addition, these devices likely provide more of a stepwise attenuation, rather than a gradual progressive attenuation.
In light of the morbidity9 and mortality rates4,7�10 encountered when attempting to achieve complete PSS occlusion via invasive surgery and the arguably satisfactory results achieved with partial shunt attenuation,12 we chose to use minimally invasive endovascular techniques to partially attenuate IHPSS in dogs when complete attenuation was not tolerated. If complete occlusion could be tolerated, it was also performed by means of endovascular techniques. Our hypothesis was that partial or complete endovascular attenuation of IHPSS in dogs would achieve similar clinical outcomes, fewer perioperative complications, and lower mortality rates, compared with outcomes reported4,7�10 following traditional open surgery.
