Hybrid Repair of Aortic Aneurysms Involving the Visceral and Renal Vessels
Article Outline
Background
We sought to analyze our experience with hybrid treatment of aortic aneurysms involving the renal and visceral arteries.
Methods
We conducted a retrospective review of 36 consecutive patients who underwent renal/visceral bypasses followed by aortic endografting. Patient demographics, medical history, operations, complications, graft patency, and patient survival were recorded. Observational and comparative analyses were performed.
Results
Mean patient age was 71 years. Mean aneurysm diameter was 6.3 cm (range 4.1-9.4 cm). Crawford aneurysm types included 1 type I, 10 type II, 12 type III, 10 type IV, and 3 pararenal aneurysms. Four patients were symptomatic. One hundred twenty-three bypasses were performed (median of three per patient), including 62 renal, 32 superior mesenteric, and 29 celiac arteries. Retrograde inflow (using the iliac arteries, aorta, or a limb of an aortobifemoral graft) was obtained in 30 patients and antegrade inflow was performed in six (three from the supraceliac aorta and three celiac branch to renal bypasses). In-hospital mortality occurred in 3 patients (8.3%). Patient survival was 80% at a mean follow-up of 6 months. Major morbidity occurred in 17 patients (47%) and included need for dialysis (5), ischemic colitis (3), failure to thrive (5), temporary paraparesis (1), and need for reoperation (7). No patient sustained permanent paraplegia. Mean length of stay was 26 days (range 8-100 days). Primary renovisceral bypass graft patency rate at 8 months was 93%. During follow-up, 14 patients developed at least one endoleak, 2 patients required percutaneous intervention, and the rest remained under observation. At last follow-up, four type 2 endoleaks and one type 3 endoleak with stable or decreasing aneurysm size.
Conclusion
Hybrid repair of aortic aneurysms involving the renal and visceral arteries is feasible with a reasonable mortality and satisfactory short-term visceral graft patency rate. However, the morbidity of the debranching procedures is high. More stringent patient selection may improve these results.
Introduction
Surgical repair of aortic aneurysms involving the visceral arteries carries high perioperative mortality and morbidity rates,1, 2, 3 making open repair of these aneurysms a daunting task for both the patient and the surgeon. Yet the risk of rupture of large aneurysm in this location warrants treatment despite considerable risk.4
Thoracic and abdominal aortic aneurysms with suitable anatomy can be treated with endovascular grafts with decreased morbidity and mortality and similar midterm results compared with open repair.5, 6, 7 Hybrid procedures have evolved to extend the benefits of endovascular treatment to aneurysms that involve the visceral arteries. The hybrid approach entails surgical bypasses to maintain perfusion of the renal and visceral arteries while allowing adequate aortic landing zones for subsequent aortic endograft attachment. By eliminating aortic cross-clamping, avoiding a thoracoabdominal incision, and decreasing intraoperative ischemia, hybrid repair is thought to improve operative survival and reduce morbidity compared with conventional surgery.8, 9 This concept was supported by good results obtained in some initial reports of debranching cases.10, 11 We present here our initial experience with hybrid repair of aortic aneurysms involving the renal and visceral arteries.
Patients and Methods
From March 2007 to April 2009, we performed renal and/or visceral aortic debranching procedures on 36 patients followed by aortic endografting on 34 patients. Patient characteristics and comorbidities are summarized in Table I. Indications for surgery included degenerative aortic aneurysm (n = 33), aortic pseudoaneurysm (n = 2), and aneurysmal dilatation after aortic dissection (n = 1). Criteria for repair included absolute aneurysm diameter, rapid enlargement, or development of symptoms. Mean aneurysm diameter was 6.3 cm (range 4.1-9.4 cm). Aneurysm extension types are listed in Table II.
Table I. Patient Characteristics and Medical Comorbidities
| Demographics | |
 Mean age (yr) | 71 (range 49-85) |
| Male | 16 (44%) |
| White | 30 (83%) |
| African American | 5 (14%) |
| Hispanic | 1 (3%) |
| Comorbidities | |
| Cardiac disease | 14 (38%) |
| Hypertension | 29 (80%) |
| Cerebrovascular disease | 15 (42%) |
| Hyperlipidemia | 19 (52%) |
| Tobacco use | 31 (86%) |
| Renal disease (GFR < 60) | 15 (41%) |
| COPD | 16 (44%) |
| DM | 6 (16%) |
| Mean ASA score | 3.4 |
Table II. Aneurysm Classification and Sizes
| Aneurysm Type | No. of Patients |
|---|---|
| Crawford type 1 | 1 (3%) |
| Crawford type 2 | 10 (28%) |
| Crawford type 3 | 12 (33%) |
| Crawford type 4 | 10 (28%) |
| Pararenal | 3 (8%) |
| Mean aneurysm size | 6.3 cm |
| Aneurysm size range | 4.1-9.4 cm |
All patients underwent debranching procedures via laparotomy. Thirty-two patients had at least one bifurcated graft placed. Straight or hand sutured branched grafts were implanted using 6-, 7-, and 8-mm-diameter, ring-reinforced, thin-walled PTFE (W. L. Gore and Associates, Flagstaff, AZ) in 24 patients (75%) (Fig. 1), while 8 patients (22%) had a Hemashield Platinum bifurcated graft (Boston Scientific, Natick, MA) placed (Fig. 2). One patient had a single visceral bypass and three patients underwent extra-anatomical hepatorenal and splenorenal bypasses (Fig. 3).
Fig. 1
Type III thoracoabdominal aneurysm repaired with retrograde debranching from both common iliac arteries followed by aortoaortic endografting. Hand-sewn bifurcated PTFE grafts anastomosed to the right common iliac artery to the superior mesenteric artery and right renal and from the left common iliac artery to the celiac and left renal. All distal anastomoses are end-to-end.
Fig. 2
Kaplan-Meier patient survival curve. At 6-month follow-up, survival was 80% with a standard deviation of 0.07.
Fig. 3
Visceral and renal artery bypass graft primary patency rate calculated with Kaplan-Meier curve. The 8-month primary graft patency rate was 96% with a standard deviation of 0.027.
The inflow site for visceral artery bypass grafting was determined individually based on the extent of the aneurysm and the quality of the iliac arteries. Retrograde inflow was obtained in 30 patients (infrarenal aorta in 3, iliac arteries in 23, and off a preexisting aortobifemoral graft limb in 4), while antegrade inflow was obtained in 6 patients (supraceliac aorta in 3 and hepatorenal or splenorenal bypasses in 3). A separate iliac conduit was created for later endografting in 7 patients. The proximal visceral artery was ligated at the time of debranching in all but two cases. In those two arteries, an Amplatzer plug (AGA Medical, Plymouth, MN) was transluminally placed during the endograft placement. Median operative time for the debranching operation was 7 hours (range 4-12½ hours). Median estimated blood loss (EBL) was 1.2 L (range 250 mL to 11 L; the 11-L blood loss occurred in a patient in whom the celiac artery stump ligature blew off while working on a renal artery anastomosis).
The aortic endografting was conducted as a separate staged procedure in 31 patients and was done simultaneously with the debranching in 3 emergent cases. Two patients did not undergo aortic endograft placement because of complications from the debranching procedure. Mean time between procedures was 39 days (median 29 days, range 0-142 days). An adequate landing zone was defined as a 20-mm length or greater of suitable aorta, iliac arteries, or preexisting aortoiliac Dacron graft. Spinal fluid drain catheters were placed in 25 patients before the endograft procedure: in 5 Crawford type IV, in 11 Crawford type III, and in all Crawford type I and II patients.
Mean operative time for the endograft procedures was 3 hours (range 1¾-5½ hours) with a mean EBL of 560 mL (range 150 mL to 3 L). A total of 100 stent-grafts were placed with a mean of 3 endografts per patient (range 1-7 stents). The types and number of grafts used are shown in Table III.
Table III. Types and Number of Grafts Used
| Type of Graft Used | No. of Grafts Used |
|---|---|
| Gore TAG | 53 |
| Cuff of the AneuRx Advantage Stent Graft | 19 |
| Cook Zenith endovascular Graftt | 9 |
| Cook Zenith TX2 endovascular graft | 11 |
| Talent | 3 |
| Other | 4 |
| Total | 99 |
This study was approved by the University of Michigan Institutional Review Board (IRB No. HUM00023437).
Results
Technical success, defined as aortic debranching followed by successful endograft deployment, was achieved in 34 patients (94%). There were three in-hospital deaths (in-hospital mortality of 8.3%). One patient died on postoperative day (POD) 6 from ischemic gut, a second patient died on POD 31 from sepsis, and a third patient died on POD 35 from pancreatitis followed by multiorgan failure.
One hundred twenty-three bypasses were performed in 36 patients (median of 4 per patient), including 62 renal, 32 superior mesenteric, and 29 celiac artery bypasses. Thirty-four patients had the aortic endograft procedure completed. Two patients did not undergo aortic endografting; one patient died from operative complications before debranching, and one patient is awaiting recovery after a prolonged hospital course following debranching. Four patients presented with symptomatic aneurysms (two with abdominal pain and an enlarging aneurysm, one with an aortobronchial fistula, and one with an aortoesophageal fistula). Three of these patients underwent emergent debranching with stent-grafting during the same operation. One of these three emergently operated patients died (33% mortality) in the postoperative period.
Following endograft placement, six patients had endoleaks on completion angiogram (five type 2 and four minor type 1 endoleaks). All type 1 endoleaks disappeared on initial follow-up CT scan.
Seventeen patients had at least one complication (47%) in the postoperative period. Table IV lists the most significant postoperative complications. One patient had transient lower extremity weakness that completely resolved before discharge. There were no strokes or permanent paraplegia cases.
Table IV. Major Postoperative Complications
| Complication | No. of Patients |
|---|---|
| Renal dysfunction | 6 |
| Need for hemodialysis | 4 |
| Re-operation | 6 |
| Myocardial infarction | 0 |
| ischemic gut | 3 |
| Late graft infection (after 30 days) | 2 |
| Prolonged respiratory failure requiring tracheostomy | 3 |
| Pulmonary embolism | 1 |
| Transient paraplegia | 1 |
| Failure to thrive | 5 |
Median hospital length of stay (LOS) for the debranching procedures was 10 days and 6 days for endograft placement, with a combined median LOS of 19 days. Twelve patients underwent both procedures during the same hospital stay. After debranching, 21 patients (60%) were discharged to home, while after endograft placement, 25 patients (81%) were discharged to home (Table V).
Table V. Discharge Status After Debranching and Endografting
| Discharge Disposition | After Debranching | After Endograft |
|---|---|---|
| Home | 21 (60%) | 25 (80%) |
| Nursing home | 2 (6%) | 6 (20%) |
| Both procedures in one admission | 12 (34%) | |
| Died | 1 | 2 |
Three patients underwent antegrade supraceliac aorticrenovisceral bypasses. Compared with the rest, this group fared worse. During debranching, they had a higher intraoperative blood loss (6.6 vs. 1.8 L, p = 0.019) and longer operative time (10:20 vs. 6:50 hours, p = 0.006), and postoperatively they had a longer LOS (mean 57 vs. 22 days, p = 0.002).
At 6 months of follow-up, the Kaplan-Meier patient survival rate was 80% (SE 0.073). Three patients died following discharge from the hospital. Two died suddenly at home after successful endograft placement on POD 7 and 52, respectively. No autopsies are available. A third patient who went into renal failure after the debranching procedure died 6 months later while receiving lytic therapy for a thrombosed hemodialysis graft.
Primary renal-visceral bypass graft patency rate at 8 months was 93% (SE 0.027). Six bypass grafts occluded during follow-up in 5 patients (five renal grafts and one superior mesenteric artery graft). One patient had bilateral renal bypass failure following severe hypotension and died in the hospital, one patient with preexisting renal insufficiency required dialysis for 4 months and then came off dialysis with a current creatinine level of 2.4 mg/dL, and a two other patients had stable renal dysfunction with an increase in creatinine level from 1.8 to 2.1 mg/dL and from 1.7 to 2.1 mg/dL, respectively. The patient with superior mesenteric artery bypass graft thrombosis had no sequelae and is tolerating a regular diet without weight loss.
During follow-up, 10 additional endoleaks were detected, in 9 patients, including nine type 2 and one type 3 endoleaks. Two endoleaks were treated percutaneously (one type 2 and one type 3). At last follow-up, only five patients remained with endoleaks, four type 2 and one small type 3 (all with stable aneurysms).
Twenty-three patients had CT angiography at least 4 months after the procedure. Seven aneurysms were stable in size and 16 aneurysms (64%) had decreased in size (mean size decrease was 1.3 ± 0.7 cm).
Discussion
Hybrid treatment of aortic aneurysms involving the visceral arteries expands the application of endovascular grafting to patients at high risk for open surgery. However, recent results with this approach suggested a disappointingly high mortality rate, produced mainly by the renovisceral debranching stage of the operation.12
The results achieved with open repair of complex thoracoabdominal aortic aneurysms in centers of excellence still carry an in-hospital mortality of 10%, a paraplegia/paraparesis rate of 16%, and a renal dysfunction rate of 17% with a 9% rate of dialysis.13 But it is well known that these excellent results are rarely obtained in all institutions.3
Persuaded by the belief that thoracoabdominal aortic aneurysms involving the visceral and renal arteries can be repaired with lower mortality and morbidity rates with a hybrid approach, compared with open thoracoabdominal surgery, during the last 2 years we have favored the hybrid approach when treating these aneurysms.
Unquestionably, branched and fenestrated endografts will play a major role in the treatment of thoracoabdominal aortic aneurysms. Currently, this technology, however, is only applicable to patients with favorable anatomy in selected centers.14, 15 Therefore, currently and perhaps in the foreseeable future, hybrid procedures may be a good alternative for some patients with high risk for thoracoabdominal surgery or with unfavorable anatomy for fenestrated and/or branched endografts.
Technical success of our hybrid approach occurred in 34 of 36 patients (94%) with mostly unfavorable anatomy for fenestrated or branched endografts because of the presence of tortuosity, occlusive disease, abundant mural thrombus, dissection, and small vessel diameter. This may compare favorably with the technical success of branched endografts, which are done only in carefully selected patients.16
The mortality and morbidity rates of hybrid procedures in our experience compare favorably with the national average for thoracoabdominal aortic aneurysm open surgery.3, 17
Our high complication rate was almost exclusively derived from the debranching procedures; however, our renal complication rate may be comparable if not better than that of fenestrated endografts.18 The reported 30-day mortality for fenestrated stent-grafts in highly selected patients is not necessarily lower than that of our experience with hybrid repair and has ranged from 0.8% to 25%.19, 20 In regard to the potential reduction of morbidity with endoluminal therapy, the Cleveland Clinic experience with endoluminal thoracoabdominal aneurysm repair carried a 47% complication rate, similar to that of our hybrid procedures. In the aforementioned reports of fenestrated and branched endografting, the reintervention rates ranged between 10% and 24%, and the endoleak rates between 10% and 19%, similar to that of our hybrid repair experience.
Although the initial sizable series of hybrid procedures reported by Lee presented a 24% mortality rate, more recent reports have documented significantly lower mortality rates, in line with our own experience.8, 21 However, the very low complication rates reported in these last two publications are in contrast with our experience, most likely the product of different methodology and patient selection. Hughes et al.’s22 recent report on six patients undergoing hybrid repair of thoracoabdominal aneurysms had no mortality and a 15% complication rate.
Our visceral bypass patency rate was 93%, with all but one graft failure occurring in renal bypass grafts. This patency rate is comparable to that of fenestrated grafts with patency rates ranging from 90% to 97%.23, 24 Roselli et al. reported a 100% visceral graft patency for branched endografts.23, 25 However, the results of branched endografting are difficult to discern because they are lumped with those of fenestrated endografts in most publications.
It is particularly encouraging the low incidence of paraplegia among our patients since we only had one case of transient paraparesis, and no cases of permanent lower extremity paralysis. It is possible that hybrid repair of aneurysms involving the visceral arteries may have an even lower paraplegia rate than that of purely endoluminal surgery, which currently carries a 4% to 13% rate of lower extremity paralysis.15, 26
Conclusion
Hybrid repair of aneurysms involving the visceral and renal vessels can be performed with reasonable morbidity and mortality rates. Our results compare favorably with those of open repair and may be similar to those of the early reports with fenestrated and branched endografts. Greater experience and better patient selection may further reduce the mortality and morbidity associated with hybrid interventions. Despite future improvement in purely endoluminal treatment of these aneurysms, it is very likely that hybrid procedures will remain very applicable and effective for the treatment of complex thoracoabdominal aneurysms.
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PII: S0890-5096(09)00228-3
doi:10.1016/j.avsg.2009.08.007
© 2009 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.
