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Interact CardioVasc Thorac Surg 2009;9:802-806. doi:10.1510/icvts.2009.210039 © 2009 European Association of Cardio-Thoracic Surgery
Elective infrarenal abdominal aortic aneurysm repair – transperitoneal, retroperitoneal, endovascular?Department of Thoracic and Vascular Surgery, University of Ulm, Steinhövelstrasse 9, 89075 Ulm, Germany Received 20 April 2009; received in revised form 17 July 2009; accepted 20 July 2009
*Corresponding author. Tel.: +49-731-500-54044; fax: +49-731-500-26705.
We retrospectively analyzed the peri-operative outcome of 210 consecutive patients undergoing elective infrarenal abdominal aortic aneurysm (AAA) repair according to the surgical approach: transperitoneal (TP; 63 patients), retroperitoneal (RP; 81 patients) and endovascular (EV; 66 patients) repair. Concerning gender, AAA diameter and classification of the American Society of Anesthesiologists (ASA score) all groups were comparable; the median age in the EV group was significantly higher (78 years vs. 68 years and 67 years, respectively, P=0.001). Mortality rates were 0% for TP, 1.2% for RP and 3% for EV repair (n.s.). Morbidity rates did not significantly differ between the groups. In specialized centres mortality rates of elective infrarenal aneurysm repair are low – regardless of the surgical approach. In such centres the best treatment options for each patient as to the surgical approach as well as peri-operative management can be provided individually.
Key Words: Aortic aneurysm; Elective repair; Transperitoneal; Retroperitoneal; Endovascular
Elective surgery of infrarenal abdominal aortic aneurysms (AAA) includes transperitoneal (TP), retroperitoneal (RP) and endovascular (EV) repair. The TP approach is considered the standard approach. The RP technique may be associated with fewer complications and offers advantages in case of hostile abdomen, horseshoe kidney and aneurysms with complex neck that may require suprarenal clamping, although prospective randomized trials revealed contradictory results [1–3]. As for EV aneurysm repair (EVAR) randomized trials have documented lower morbidity and mortality rates as compared to open surgery [4, 5]; yet these results were obtained in carefully selected patients that were suitable for both – open and EV repair. In the mid- and long-term re-interventions after EV, repairs are common and lead to considerable morbidity rates not different from open repair [6]. Due to the minimal invasive nature of EV repair this technique is favoured in older and high-risk patients unfit for open surgery. Although the EVAR-2 trial did not demonstrate long-term benefit of EVAR for that group of patients, it is offered if patients fall between the EVAR-1 and EVAR-2 criteria [7]. In our institution of a high volume (>60 AAA repairs per year) all three techniques – TP, RP and EV repair – are well established and we analyzed the peri-operative outcome of 210 consecutive patients undergoing elective AAA repair according to the method of aneurysmectomy: TP – RP – EV.
2.1. Data analysis We retrospectively analyzed a prospective database of 210 consecutive patients undergoing elective AAA repair (63 patients TP, 81 patients RP and 66 patients EV) at the Department of Thoracic and Vascular Surgery at the University Hospital of Ulm between August 2005 and October 2008. Each group was compared for demographic data and peri-operative outcome including hospital mortality, need for assisted mechanical ventilation (AMV), length of stay (LOS) on intensive care unit (ICU), blood units transfused, day of discharge and surgical and medical complications according to the defined variables (Table 1). After EV repair the type and frequency of endoleakage was documented.
2.2. Statistical analysis For discrete variables absolute and relative frequencies are given. For continuous frequencies median values and range are applied. To calculate significance of morbidity/mortality in the treatment groups,  2-test was used; P<0.05 were regarded to be significant. To calculate significance concerning total operative time, duration of ICU treatment, blood units transfused and day of discharge, Kruskal–Wallis ANOVA on ranks was applied. Statistical analysis was performed in collaboration with the Department of Biometry using the computer program SigmaStat. 2.3. Peri-operative management Elective aneurysm repair in our institution is performed under general anesthesia in part with supplementation of epidural anesthesia (EDA) and under a single shot antibiotic therapy with cefuroxime (1.5 g). All patients are extubated immediately if they fulfil the following criteria: core temperature >36 °C, hemodynamic stability without need for catecholamine therapy and exclusion of residual paralysis. After AAA repair patients are routinely transferred to the ICU for overnight observation and transferred to the surgical floor on postoperative day #1 if they fulfil the following criteria: stable hemodynamic parameters, no clinical signs of organ failure and stable laboratory tests (e.g. hemoglobin).2.4. Patient selection and surgical technique The TP approach is preferred in patients with concomitant iliac aneurysms and achieved via a midline incision; the RP incision with posterolateral approach to the aorta as supposed by Willliams et al. [3] is preferred in patients with hostile abdomen, horseshoe kidney or anatomically complex neck that may require suprarenal clamping. All grafts used were made of Dacron and either tube of bifurcated grafts depending on the presence or absence of iliac aneurysms. EVAR is predominantly considered in patients regarded to be at high risk on the basis of clinical, functional and laboratory criteria. Reasons for EV repair in our series were severe chronic obstructive pulmonary disease (COPD) (30%), history of myocardial infarction/coronary heart disease (29%), congestive heart failure (18%), hostile abdomen (6%) and morbid obesity (4.5%). Morphological criteria for EV repair are minimal neck of 1.5 cm without thrombus, angulation of the iliac vessels <90° and femoral arteries suitable for the approach. In patients that do not meet these criteria aorto-uni-iliac (AUI) stentgrafts in combination with femoro-femoral cross-over bypass may be implanted. Endografts used were from COOK, Medtronic and Gore.
3.1. Demographic data Table 2 gives an overview over demographic data of the analyzed patients. Concerning gender, aneurysm diameter, classification of the American Society of Anesthesiologists (ASA score), preoperative hemoglobin and baseline creatinine in all three groups were comparable; as for patient age, the EV group was significantly older than were patients who underwent open repair. As for implanted grafts in the open groups, there were significantly more tube grafts implanted in the RP group (73 vs. 30, P<0.05). In the EV group the majority received bifurcated grafts, 10 patients had AUI grafts combined with femoro-femoral cross-over bypass. In two patients conversion to open repair was necessary due to intra-operative stentgraft dislocation. In the open groups, 47% (TP) and 56% (RP), respectively, were supplemented with EDA.
3.2. AMV, ICU, blood units transfused, day of discharge, in-hospital mortality The peri-operative outcome measurements are depicted in Table 3. EV repair had significantly shorter total operative time and significant decreased need for postoperative AMV as compared to the TP group (3% vs. 20.6%, P=0.004). The transfusion of banked blood was significantly lower in the EV group as compared to the RP group (median 0 vs. 2; P=0.001). Duration of ICU treatment and day of discharge did not significantly differ between the groups. In hospital three patients died during our observation period: one patient in the RP group and two patients in the EV group due to secondary rupture and mesenteric infarction, respectively, resulting in an in-hospital mortality of 0% (TP), 1.2% (RP) and 3% (EV) (n.s.).
3.3. Surgical complications Detailed overview over surgical complications and frequency of re-operation is given in Table 4. Peripheral ischemia with the need for embolectomy occurred in three (TP), four (RP) and two (EV) patients, respectively. Ischemic colitis requiring re-operation and bowel resection occurred in two patients in the RP and in three patients in the EV group. Spleen rupture and ureter lesion occurred in three patients in the RP group. Other surgical complications included graft occlusion, ileus requiring a stoma and incisional hernia in the TP group; in summary the frequency of re-operation in the groups was 12% (TP), 11% (RP) and 7.5% (EV).
3.4. Endoleaks after EV repair Before discharge, EV patients undergo routine CT control. In four patients no postoperative control was undertaken – two patients that were converted to open repair and two patients that died within two days postoperatively. In 24 of the remaining 62 patients endoleaks could be detected (38.7%), the majority being type II leaks: 19/62 (30%); in five cases type I and type III leaks were suspected. These patients underwent short-term follow-up (after three months) with no secondary intervention and the suspected leaks resolved over time with regression of the aneurysm sac (Table 5).
3.5. Medical complications Medical complications according to the defined variables were documented during the postoperative course as follows (Table 6): cardio-pulmonary complications in seven (TP), six (RP) and six (EV) patients in the groups; acute renal failure (ARF) was in five (TP), nine (RP) and eight (EV); one patient each in the TP and RP group and two patients in EV group required postoperative dialysis; as for gastrointestinal complications, we had the highest rate of subileus after TP (14%) repair. Altogether, the RP group showed the lowest rate of medical complications (28.3%); the EV group had the highest rate with 39.3%. TP group had 30.1% (n.s.).
Contemporary treatment of elective AAA repair includes open repair via either TP or RP approach and minimal invasive EV repair via access through the femoral arteries. As for open repair, some authors have claimed advantages of the RP over the TP approach although prospective randomized trials revealed contradictory results [1, 2]. As for EVAR, large multicentric trials have demonstrated advantages concerning blood loss, length of stay on ICU and overall morbidity and mortality in patients that are suitable for both approaches: open and EV [4, 5]; yet these advantages may be counterbalanced in the long-term by the rate of reinterventions: 9% in the fourth year including both major reinterventions (e.g. open repair with in-line or extra-anatomical bypass, conversion to open repair) and minor reinterventions whereby the majority are minor reinterventions [6]. On the other hand, open repair is accompanied by higher peri-operative morbidity and mortality rates. EV repair as a minimal invasive procedure appears to be attractive in patients deemed unfit for open aneurysm exclusion [7]. Analysis of our data according to the surgical approach revealed that the median age in EV patients was significantly higher (78 years) than in patients undergoing TP (68 years) or RP (67 years) repair. Other demographic data (ASA classification, gender, AAA diameter, preoperative hemoglobin and baseline creatinine) were comparable. Intra- and postoperative data showed no significant differences between the RP and TP approach, but demonstrated clear advantages of EV in terms of need for AMV, blood units transfused and total operative time. The in-hospital mortality was comparable in all groups and ranged from 0 to 3%, rates that are in line with the results of other investigators who describe mortality rates of 3.5% for open and 2.7% for EV repair [8]. The reason for the lack of difference between TP, RP and EVAR may be the older age of EV patients on the one hand and, on the other hand, the fact that in institutions where EV and open techniques are well established, mortality rates of open repair are also low [9]. A systematic review in older aged patients has described a pooled mortality rate of 4.6% in this high-risk group [10]. Duration of ICU treatment was similar in all groups as in our institution all patients are routinely transferred to the ICU for one night. ICU stay in other centres where open as well as EV repair is performed is up to four days [11]. The frequency of re-operation ranged from 7.5% to 12% in the groups with no significant difference; specific surgical complications in the RP group that must be attributed to the approach were spleen rupture and ureter lesion – complications that have already been described [12]. Ischemic colitis and mesenteric infarction developed in 2.4% in the RP group and in 4.5% in the EV group – a complication that occurs in 1–6% after open as well as after EV aneurysm exclusion [13]. A specific feature which is unique to EV repair is the occurrence of endoleaks whose frequency ranges from 24% to 39% [14]; in our series in 38.7% endoleaks were documented, the majority being type II leaks with no need for immediate intervention. Other types of leakage resolved over time without secondary intervention. One patient died due to secondary rupture postoperatively, a rare condition in the early postoperative period, but a late complication of EVAR which must be attributed to incomplete aneurysm exclusion [15]. Surprisingly, overall morbidity showed the highest rate after EV with 39.9%, followed by TP (30.1%) and RP repair (28.3%). This observation may be attributed to two issues: First, the EV patients had significantly older age. Second, in high volume centres where open as well as EV repair is well established complication rates for open repair are also low [9]. In summary, our analysis documented advantages for the EV technique in elective infrarenal aneurysm repair concerning blood transfusion, operative time and need for AMV. Nonetheless, application of EV is not without significant morbidity if used predominantly in older patients. In this high-risk group organ failure due to pre-existing co-morbidities eliminates the advantages of the minimal invasive approach. We feel that patients with AAA should be referred to high volume centres where open as well as EV repair is well established and the best treatment options regarding the surgical approach and peri-operative management can be provided for each patient individually.
We would like to thank Gisela Bischoff, Gunter Lang, Jochen Kick and Hubert Schelzig who have substantially contributed to the acquisition of data.
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Abstract
1. Introduction