Endovascular Treatment of Ruptured Infrarenal Aortic Aneurysms

Theoretical Considerations

EVAR has been used increasingly to treat rAAA and offers many theoretical advantages over open AAA repair. It is less invasive, eliminates damage to periaortic and abdominal structures (especially large adjacent veins), decreases bleeding from surgical dissection, minimizes hypothermia, and lessens the requirement for deep anesthesia. Because of these potential advantages, together with the reports of lower procedural mortality in case series, EVAR has been deemed superior to open repair for the treatment of rAAA.

A Single Center Experience

Between April 22, 1994, and January 15, 2008, 57 patients with rAAAs were treated at Montefiore Medical Center in New York. Briefly, after an initial experience of EVAR in 12 patients with rAAA who were deemed unsuitable for open surgical repair (17% 30-day mortality), the policy adopted was to use EVAR for all patients with suitable anatomy if appropriate staffing and endografts were available. A total of 45 patients were treated with endografts and 12 with open repair. In the patients who underwent EVAR, 25 received surgeon-made endografts and 20 received industry-made modular endografts. The surgeon-made endografts were constructed from a large balloon-expandable stent and a tulip-shaped polytetrafluoroethylene (PTFE) graft placed in an aortounifemoral position with contralateral iliac artery occlusion and a femorofemoral bypass. Twelve of the 57 patients with rAAA underwent open repair: 10 because their anatomy was unsuitable for EVAR and two because staff or grafts were not available. Many of the patients treated with EVAR were prohibitive risks for open repair, yet many of these survived EVAR.

EVAR was performed without a preprocedural computed tomography (CT) scan in 17 patients. In these patients, intraoperative arteriography using calibrated catheters was used to determine suitability for EVAR and to make measurements for graft sizing. A preprocedural CT scan was obtained in the other 28 patients owing to uncertainty in the diagnosis or because the patient was initially admitted to another hospital or service. No differences in outcomes were observed between these two small groups.

Fluids were aggressively restricted and the patient’s blood pressure was allowed to fall to 50 mm Hg without fluid administration, or lower if the patient was moving or talking. Although local anesthesia was used in the early phases of most EVAR procedures (placement of catheters, guidewires, and sheaths), general anesthesia was used to prevent motion in order to optimize imaging and allow precise endograft deployment.

Large sheath placement and balloon occlusion were used only in the case of complete cardiovascular collapse and were required in 10 of 45 patients undergoing EVAR and three of 12 undergoing open repair. The technique for continuous balloon control of the aorta while deploying a modular endograft has been described by several groups including our own. This technique is somewhat complex and must be carried out properly to achieve the optimal results. It is important that large sheath and balloon placement only be used when it is clearly needed, that aortic control not be lost until the rupture site has been excluded, and that the large sheath for the balloon placement be fixed in place to support the balloon and to permit its withdrawal from above the deployed endograft.

Abdominal compartment syndrome was detected in only three of the 45 patients undergoing EVAR when they became hypotensive and difficult to ventilate. Laparotomy and evacuation of the hematoma relieved the problem. However, unrecognized compartment syndrome probably contributed to fatal multiorgan failure in some patients. Six of the 45 patients treated by EVAR and one of the 12 patients treated by open repair died within 30 days.

Collected World Experience

Data from 49 centers around the world performing EVAR for rAAAs were collected between July 1, 2002, and January 15, 2009. Data from the 13 centers that were committed to EVAR and performed this procedure on all or almost all patients with rAAA who had suitable aortic neck and iliac artery anatomy were updated to January 15, 2009. These updated data, as well as all the data from the other centers, were reported by us in the Annals of Surgery in November 2009.

Data from 1037 patients with a rAAA or a ruptured aortoiliac aneurysm treated with EVAR show an overall 30-day mortality of 21.2%, which is clearly lower than the rates of 35% to 55% with open repair for rAAAs reported in multiple studies. However, many of the centers in the collected experience had limited the use of EVAR to stable patients with a rAAA or even those with contained ruptures. Because hemodynamic instability is associated with a higher risk of procedural mortality after open repair, it is invalid to compare procedural mortality with EVAR and open repair in this way.

Because of this, the updated outcomes for EVAR were examined in the selected group of patients from 13 centers that were committed to performing EVAR to treat rAAAs in all patients with anatomy suitable for endograft treatment, including those who were hemodynamically unstable and those in profound shock. These centers were usually the ones with the greatest experience in treating rAAAs. Although there was some variability in the approach used in these centers to the treatment of patients with rAAAs, most had some degree of standardization and many had a defined protocol. All were experienced in the use of EVAR and endovascular adjuncts for elective treatment of abdominal aneurysm, and all had dedicated endovascular facilities and imaging equipment. The use of EVAR to treat almost all patients having a rAAA with suitable anatomy was associated with a favorable 30-day mortality of 19.7% in 680 patients (range, 0% to 32%). During this period, these 13 centers performed open repair for rAAAs in 763 patients whose anatomy was unsuitable for EVAR. The 30-day mortality for open repair was 36.3% (range, 8% to 49%; p <.0001 for EVAR vs. open repair).

These updated comparative outcome results (30-day mortality of 19.7% for EVAR vs. 36.3% for open repair from the 13 centers committed to EVAR of as many rAAAs as possible) strongly suggest that EVAR is a superior way to treat rAAAs in patients whose aortic neck and iliac anatomy are suitable for endovascular graft treatment. Additional proof that EVAR is a better treatment for some patients with rAAA is that many patients who were categorically unsuitable or prohibitively high risk for open repair in this collected experience survived for many years after EVAR.

Why are results variable?

Several possible reasons might explain the discordant results reported by different authors for treatment of rAAAs by EVAR. These include strategies, adjuncts, and technical factors that are thought to influence the outcome of EVAR for rAAAs and that probably account for the favorable outcomes with EVAR in the 13 centers in the collected experience. Some of the key reasons are described here.