Outcome after celiac artery coverage during endovascular thoracic aortic aneurysm repair: Preliminary results
Article Outline
Background
Endovascular repair of descending thoracic aortic aneurysms has emerged as an alternative to open repair. Coverage of the left subclavian origin has been reported to expand the proximal sealing zone. We report the planned coverage of the celiac artery origin with a thoracic stent graft to achieve an adequate distal sealing zone.
Methods
All patients undergoing endovascular aneurysm repair are prospectively entered into a computerized database. All patients who underwent thoracic endovascular aneurysm repair with coverage of the celiac artery origin were identified and retrospectively analyzed. End points for evaluation included indications for covering the celiac artery, anatomic features of the distal landing zone, demonstration of collateral circulation between the celiac artery and the superior mesenteric artery, technical success of the procedure, and presence of clinical ischemic symptoms after the procedure.
Results
Between March 2005 and May 2006, 46 patients underwent endovascular repair of descending thoracic aortic aneurysms. Seven patients had planned celiac artery coverage with a thoracic stent graft to secure an adequate distal sealing zone. Six patients demonstrated collateral circulation through the gastroduodenal artery between the celiac and superior mesenteric arteries before deployment of the stent graft. One patient had a distal type I endoleak at the conclusion of the procedure related to inadequate sealing at the superior mesenteric artery origin. No type II endoleaks were evident at the final intraoperative angiogram or 30-day computed tomography scan. There were no postoperative deaths, no ischemic abdominal complications, and no clinical spinal cord ischemia. Short-term follow-up (1 to 10 months) has demonstrated no additional endoleaks (type I not fully assessed), no aneurysm growth, and no aneurysm ruptures.
Conclusion
This limited series supports the suitability, in selected patients, of covering the celiac artery origin for a distal landing zone when the distal sealing zone proximal to the celiac artery is inadequate. We recommend the angiographic evaluation of the collateral circulation between the celiac and superior mesenteric arteries when covering the celiac artery origin is being considered.
Endovascular repair of descending thoracic aortic aneurysms (DTA) has emerged as an alternative to open repair in selected patients. Early reports of stent graft repair of DTA suggest that it is a less invasive option, with decreased perioperative mortality and morbidity rates compared with an open thoracic or thoracoabdominal approach.1, 2, 3
Inclusion criteria for thoracic stent graft placement consists of a proximal sealing zone 20 mm distal to the left common carotid artery and a distal sealing zone 20 mm proximal to the celiac axis. As with infrarenal graft repair of abdominal aortic aneurysm (AAA), inadequate proximal and distal sealing zones are limiting factors for endovascular treatment of DTA. Coverage of the left subclavian origin without carotid-to-subclavian revascularization in symptomatic patients has been reported to extend the proximal sealing zone and is generally well tolerated when the right vertebral artery is of normal size.4, 5
When the distal landing zone proximal to celiac artery is inadequate, either a thoracoabdominal approach or debranching of visceral vessels is required, followed by thoracic stent grafting. Another alternative includes extending the distal landing zone by covering the celiac artery origin. The feasibility of covering the celiac artery and associated clinical implications and outcomes has, to our knowledge, not been reported. We report the planned coverage of the celiac artery origin to increase the length of the distal sealing zone for endovascular treatment of DTA.
Methods
After our initial experience with thoracic stent grafting for DTA, we sought to extend the application of this procedure in high-risk patients with an inadequate distal sealing zone. These patients’ computed tomography angiograms (CTA) of the chest and abdomen were analyzed, and celiac and superior mesenteric artery (SMA) origins were assessed for ostial narrowing or occlusion. Mesenteric circulation was evaluated by selective mesenteric angiography as part of the preoperative evaluation or during the index thoracic stent grafting procedure.
Patients who underwent endovascular repair of descending thoracic aortic aneurysms with coverage of the celiac artery were prospectively identified and their data maintained in a computerized vascular surgery database. A retrospective analyses was done of the anatomic features of the distal landing zone, flow pattern of the mesenteric circulation, including demonstration of collateral circulation between the celiac artery and the SMA, and technical success of the procedure. Clinical charts were reviewed for the presence of chemical markers for visceral ischemia or malperfusion.
A selective mesenteric angiogram was performed preoperatively or at the index operation to assess collateral circulation between the celiac artery and the SMA as well as the additional sealing zone gained from celiac artery coverage. The initial aortogram was performed in a lateral projection to visualize the origins of the celiac artery and SMA with selective mesenteric injections to assess collaterals. Temporary mesenteric artery occlusion was not used during this evaluation.
Operative procedures were performed using general anesthesia. All implanted devices were TAG thoracic endoprosthesis (W.L. Gore and Associates, Flagstaff, Ariz) with one exception in which a Gore Excluder aortic cuff was used as an additional distal component.
Patients were assessed during the immediate postoperative period for the presence of visceral ischemia, including pain, acidosis, leukocytosis, or fever. During follow-up, CT scans and physical examinations were performed at 1 and 6 months. Imaging studies were reviewed for device migration, sac size, and endoleaks.
Results
Between March 2005 and May 2006, 46 patients underwent endovascular repair of DTA. Seven (15%) had planned celiac artery coverage with a thoracic stent graft to achieve an adequate distal sealing zone. The mean patient age was 74 years, and the mean aneurysm size was 71 mm (Table). Endovascular reconstruction with coverage of the celiac origin was advised for patients who were considered high risk for open thoracoabdominal reconstruction. All procedures were elective, and none of the aneurysms were leaking.
Table. Patient demographics, aneurysm features, and celiac artery status before and after treatment
| Patient | Age (years) | Gender | Indication | High risk status | Additional sealing distance gained by covering celiac origin | Celiac artery status | |
|---|---|---|---|---|---|---|---|
| Pre-op | Post-op | ||||||
| 1 | 71 | M | 7-cm TAA | COPD | 20 mm | Normal | Patent by collaterals |
| 2 | 74 | F | 6-cm TAAA; 5-cm AAA (hybrid)⁎ | COPD | 9mm† | Plaque with stenosis | Patent by collaterals |
| 3 | 72 | M | Distal type I endoleak‡ | Prior open and TEVAR | 14mm | Normal | Patent by collaterals |
| 4 | 66 | M | 7-cm TAAA | Recent CABG, COPD | 25mm | Normal | No contrast imaging |
| 5 | 86 | M | Distal type I endoleak‡ | Age | 21mm | Stenotic from ligament compression | Patent by collaterals |
| 6 | 74 | F | 8.1-cm TAA | Renal insufficiency | 15mm | Plaque with stenosis | Patent by collaterals |
| 7 | 74 | M | 7.5-cm TAA | Prior TAA repair ×2 | 14mm | Normal | Patent by collaterals |
⁎Underwent infra-renal Dacron graft repair with debranching of both renal and superior mesenteric artery with stent graft repair of TAAA. |
†Additional “debranching” with bypass of superior mesenteric artery to provide longer sealing zone for distal site. |
‡Previous endovascular thoracic aortic aneurysm repair. |
Five patients had a short distal neck (<20 mm) proximal to the celiac artery with aortic diameters >37 mm. In two patients, a prior endograft had been placed, but a late distal type I endoleak developed. By covering the celiac origin, a mean of 16.9 mm (range, 9 to 25 mm) of additional sealing zone was obtained. All celiac origins were patent on preoperative imaging, but three of seven patients had obstructive lesions at the ostium.
Intraoperative
Our first patient had both thoracoabdominal and infrarenal aneurysms, with a short infrarenal neck. She underwent a hybrid procedure with open infrarenal aneurysm repair, including visceral vessel bypass grafting and a subsequent thoracic stent graft covering the celiac artery, which was not bypassed but had moderate proximal stenosis. Her completion intraoperative angiogram showed good collateral flow to the celiac branches. She recovered on an expected course without visceral ischemic symptoms. Later patients underwent more extensive perioperative selective visceral angiography to document collateral circulation between the celiac artery and the SMA through the gastroduodenal artery.
We were not able to demonstrate communication via the gastroduodenal artery preoperatively in only one patient, but celiac coverage was later undertaken, with a postdeployment angiogram that showed collateral flow to the celiac branches. She reported abdominal pain on the first postoperative day. This was investigated with ultrasound imaging that showed retrograde hepatic flow filling antegrade into the splenic artery. The symptoms resolved, and the patient recovered without further clinical sequelae.
No suspicious symptoms developed in the other patients, and no postoperative pyrexia developed. One patient developed a leukocytosis of 16,300 × 103/μL (normal, 4000 to 11,000 × 103/μL) but remained without fever or symptoms. All other patients had first day postoperative white blood cell count of ≤11,200 × 103/μL. Lactate, amylase, and synthetic liver function were variably evaluated and were not significantly elevated. There were no demonstrable type II endoleaks and no clinical evidence of spinal cord ischemia. No patients died perioperatively (≤30 days).
In two patients with previous thoracic stent grafts, distal type I endoleak developed that required distal extension covering the celiac origin as a second procedure. One of these patient’s distal type I endoleak was related to proximal migration of the stent graft secondary to severe angulation of the descending thoracic aorta immediately above the diaphragm. Both were treated with distal extension of the stent graft covering the celiac artery. One patient remained with a distal type I endoleak related to inadequate sealing at the SMA origin despite celiac origin coverage.
Imaging surveillance
Two patients were evaluated with additional imaging before discharge after the index operation. In one patient (already mentioned), an ultrasound study demonstrated retrograde flow from the hepatic artery with antegrade flow in the splenic artery. CTA in the second patient showed filling of the branches of the celiac artery with occlusion of the celiac origin but no endoleak.
In the remaining five patients, CT imaging was done 1 month after the procedure (one without contrast). All contrast imaging showed that the celiac origins were covered with short segment occlusions, but the hepatic and splenic branches remained patent (Fig 1). No type II endoleaks were evident. The single noncontrast CT showed stable position of the stent graft. Ultrasound scanning was not undertaken. Two patients have had a 6-month contrast CT without change in celiac findings, no additional endoleaks, no aneurysm growth, and no aneurysm ruptures. One patient died from a cardiac event 4 months after the index procedure.
Fig 1.
A computed tomography angiogram shows the collateral circulation between the celiac artery and the superior mesenteric artery after deployment of the endograft.
Discussion
Although endovascular treatment of thoracic aortic aneurysm was evaluated in 1994,6 commercial availability and United States Food and Drug Administration approval of a thoracic endograft for treatment of DTA took more than a decade. Endovascular DTA repair has been demonstrated to be a safe alternative to open repair with low mortality, morbidity, and intermediate results.2, 3, 7, 8 Similar to endovascular repair of AAA, inadequate proximal and distal sealing zones are common limiting factors for the placement of thoracic stent grafts.
Coverage of the left subclavian artery with the stent graft to achieve a proximal sealing zone has been reported and is well tolerated in selected cases.4, 5 Thoracic aortic aneurysms with an inadequate distal landing zone proximal to celiac artery are difficult to successfully treat without adjunctive procedures. Debranching with visceral vessel relocation to lengthen the distal landing zone for the thoracic stent graft is a surgical option in patients with aneurysms involving the visceral vessels9, 10, 11; however, these patients require a laparotomy for visceral bypass. Considering this extra operative time, expense, and added morbidity, covering the celiac artery with the stent graft may provide a better alternative.
Mesenteric ischemia and associated complications related to embolic phenomena have been reported after thoracic aortic stent grafting.12, 13 In one report, this complication was attributed to compressed iliac limb proximal to the inflow of the mesenteric bypass graft. Grabenwoger et al12 attributed mesenteric ischemia secondary to partial coverage of the celiac artery as the possible cause for multiorgan failure for a single patient in their series of thoracic stent graft procedures.12 Sunder-Plassman et al14 discussed the possibility of covering the celiac artery to extend the distal landing zone in presence of collaterals from the SMA for the treatment of distal type I endoleak after thoracic stent graft placement.
Considering all of our patients underwent calculated coverage of the celiac origin, we may have prevented visceral embolization from a partial coverage of the celiac origin. The short main trunk of the celiac artery combined with the rich collateral network feeding the hepatic and splenic branches likely provides the continued patency of these branch vessels. In addition, the complete coverage of the celiac origin prevented retrograde filling into the aneurysm sac (type II endoleak). The absence of type II endoleaks could also be related to the proximal occlusive disease at the celiac artery that was present in three patients.
Significant stenosis of the celiac artery secondary to atherosclerosis and median arcuate ligament compression has been reported in asymptomatic patients.15 Isolated critical stenosis or occlusion of celiac artery rarely causes symptomatic mesenteric ischemia because of the temporal development of rich collateral vessels from the SMA.16, 17 Pancreaticoduodenal arcades and the dorsal pancreatic arteries are the most commonly noted collateral pathways.18 Branches of the gastroduodenal artery and inferior pancreaticoduodenal arteries (arising from SMA) communicate to form the anterior and posterior pancreaticoduodenal arcades. The dorsal pancreatic artery, usually the first large pancreatic branch of the splenic artery, communicates with the pancreaticoduodenal arcades; and the SMA, or one of its branches, forms another collateral pathway between celiac artery and SMA. These multiple collateral pathways allow increased flow from the SMA to branches of the celiac artery after covering the celiac origin. In our study, all patients demonstrated collateral circulation between the SMA and celiac artery after the celiac artery was covered with the stent graft (Fig 2).
Fig 2.
Angiogram demonstrating (left) TAG device before deployment covering the celiac artery and (right) filling of celiac artery branches after covering the celiac artery. (SMA, Superior mesenteric artery.)
This small series, with only short-term surveillance, had limitations. Patients were evaluated postoperatively for clinical signs of visceral ischemia. Considering that clinical evaluation is subjective and laboratory findings may not show any significant changes before critical ischemia, immediate intervention was considered for patients if symptoms developed. Although no patients showed these definite signs of ischemic foregut, subclinical ischemia of dysmotility and delayed organ dysfunction could remain undiagnosed, however. Gastric exercise tonometry has recently been reported as method of evaluating foregut ischemia in patients with celiac artery occlusive disease.19 We did not undertake tonometric evaluation in our series. Longer follow-up scans might also show signs of splenic or hepatic infarction if embolization does appear in the delayed setting. In addition, we did not undertake endoscopy and formal motility studies that might demonstrate ischemic mucosal changes or functional problems in the foregut.
Conclusion
Coverage of the celiac artery may be an acceptable endovascular approach in treating selected patients with descending thoracic aneurysm repair. Owing to the presence of extensive collateral circulation between the celiac and superior mesenteric arteries, mesenteric ischemic symptoms appear uncommon after covering the celiac artery during endovascular repair of the descending thoracic aorta. Angiography is recommended to assess the collateral circulation before the planned coverage of the celiac artery. Further study of celiac artery coverage is also recommended before widespread application for treating aneurysm patients with limited distal anatomic landing zones.
Author contributions
References
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Competition of interest: none.
PII: S0741-5214(06)02096-9
doi:10.1016/j.jvs.2006.11.040
© 2007 The Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
