Endovascular approach in isolated abdominal aortic dissections

Abstract

Background

Here, we report the mid-term results of endovascular treatment of isolated dissection of the abdominal aorta, which is a very rare pathology.

Materials and methods

A total of 11 patients (4 males (36.3%) and 7 females (63.6%)) aged 42–72 (mean, 60.3 ± 10.45) years with isolated dissection of the abdominal aorta underwent endovascular stent-graft treatment at our institution between August 2010 and September 2015. Eight patients were symptomatic, and the remaining three were asymptomatic. The asymptomatic patients had aortic aneurysms coexisting with dissection. Eight patients without aneurysm had spontaneous dissections, and the most common symptom was unresponsive abdominal pain.

Results

The mean abdominal aorta diameter was 46.7 ± 20.6 (range, 31.2–100.9) mm and the mean dissection length was 71.1 ± 47.3 (range, 17–162) mm. Aorto-bi-iliac stent grafts were used in all patients, and were placed successfully under spinal anesthesia in all but one (90.9%) patient. Occlusion developed in one patient due to compression of the aorto-bi-iliac graft. Right–left femoral–femoral bypass was performed in this patient, who could not be placed on the opposite side. In addition, the graft was placed in one patient using the left renal artery chimney technique. No intraoperative mortality occurred, and open surgery was not required. In addition, no death occurred and no additional intervention was required during the mean follow-up period of 25.5 ± 17.1 (range, 6–60) months.

Conclusion

Limited data regarding endovascular treatment of isolated dissection of the abdominal aorta are available in the literature. Based on data obtained in a limited number of patients, we consider endovascular aortic repair to be a good alternative to surgery due to its low morbidity and mortality rates.

Keywords

Abdominal aortic dissection endovascular repair

Isolated dissection of the infrarenal abdominal aorta is a rare condition in the absence of trauma or coexisting aneurysm. The male/female ratio for dissection ranges from 2:1 to 5:1.¹ Isolated dissection of the abdominal aorta (IDAA) was reported in only 1% of an autopsy series of 182 aortic dissection cases.² This condition is usually diagnosed incidentally by computed tomography (CT) performed for other reasons in asymptomatic patients.

The mortality rate is usually high during medical follow-up and treatment of IDAA. Therefore, surgical or endovascular methods are recommended in such cases.³ Endovascular treatment is increasingly being adopted for this rare clinical condition, as for other aortic pathologies. A limited number of reports regarding IDAA are available in the literature.³ Here, we report the mid-term results in patients with IDAA treated using the endovascular method.

Materials and methods

Endovascular treatment was applied in 313 patients due to thoracic and abdominal aortic pathologies between August 2010 and September 2015 in our hospital, which is a reference hospital for aortic aneurysms and dissection in our region. Data from 11 (3.5%) patients with IDAA who were treated using endovascular methods and followed were evaluated retrospectively in this study. Three patients with no aneurysmal dilatation or pain (aortic diameters: 25, 26, and 28 mm) who were considered to have chronic dissection were not included in the study. All radiological images and preoperative, perioperative, and postoperative data were analyzed and recorded.

Three of 11 (27.2%) patients were asymptomatic, with dissection detected incidentally. The remaining eight (72.7%) patients were symptomatic, with sudden, sharp abdominal and inguinal pain as the most common symptom. They had aortic diameters that exceeded the normal value of 3 cm, together with abdominal pain that did not resolve despite kidney ischemia and medical treatment. Eight symptomatic patients had spontaneous dissection with no underlying iatrogenic cause. And no dissection were present in the internal or external iliac artery of the patients.

All patients had at least one comorbidity and risk factor. The demographic characteristics of the patients are presented in Table 1.

Table 1.

Demographic characteristics of the patients.

Variables	N	%
Hypertension	11	100
Diabetes	3	27.7
Active smoking	8	72.7
COPD	2	18.1
Asymptomatic	3	27.7
Symptomatic	8	72.7
Left iliac dissection	3	27.7
Right iliac dissection	4	36.3

COPD: chronic obstructive pulmonary disease.

All patients underwent CT angiography to investigate the anatomical appropriateness for endovascular repair. Grafts with the appropriate diameters and lengths were selected based on CT angiography findings.

The indications for treatment included aortic rupture, abdominal pain that was unresponsive to medical treatment, risk of renal malperfusion, and aortic diameter >3 cm, together with dissection (Table 2).

Table 2.

Summary of all patients who underwent endovascular surgery.

Patient	Age	AA diameter (mm)	Symptom	İndication	Dissection length (mm)
1	47	38	Abdominal pain	Irresponsive pain + Aortic diameter >3 cm	138
2	64	67	Asymptomatic	Aortic diameter >3 cm	99
3	52	31	Abdominal pain	Irresponsive pain + aortic diameter >3 cm	66
4	42	32	Abdominal pain	Irresponsive pain + aortic diameter >3 cm	55
5	72	60	Asymptomatic	Aortic diameter > 3 cm	162
6	63	41	Abdominal pain	Irresponsive pain + aortic diameter >3 cm	42
7	72	43	Abdominal pain	Irresponsive pain + aortic diameter >3 cm	33
8	62	31	Abdominal pain	Irresponsive pain + aortic diameter >3 cm	114
9	53	33	Abdominal pain	Irresponsive pain + aortic diameter >3 cm	21
10	72	33	Abdominal pain	Irresponsive pain + aortic diameter >3 cm	17
11	65	100	Asymptomatic	Aortic diameter >3 cm	36

AA: abdominal aorta.

Medical treatment was applied in patients with abdominal pain to provide analgesia and arterial systolic pressure control (≤120 mmHg) for 48 h. Patients who did not respond to medical treatment were prepared for the endovascular procedure. Written informed consent was obtained from all patients prior to the procedure.

Procedure

Polytetrafluoroethylene (PTFE)-coated stent grafts (Gore-Excluder®, Gore-Tex; W.L. Gore & Associates, Flagstaff, AZ) was used in all patients. Stent graft selection was performed as follows: when dissection extended to the neck of the aorta into which the stent graft would be inserted, a diameter 10–15% larger was selected; when the dissection did not extend to the neck, a diameter 10–30% larger was selected. Stent grafts with diameters 10–20% larger than the distal iliac artery diameter were used. A cardiovascular surgeon, an interventional radiologist, and an anesthesiologist performed the procedures under sterile conditions in the angiography laboratory. The procedure was performed under spinal anesthesia in all patients. Both femoral arteries were opened surgically and the aorto-iliac grafts were inserted. The stent grafts were positioned so as to begin from below the renal arteries. Control angiography was performed from the diagnostic catheter after graft insertion, and graft patency and potential leakage were evaluated. Aortic balloon dilatation was performed for distal and proximal leakage in appropriate patients. Revascularization procedures were performed using the chimney graft method in proximal renal arteries and the femoral–femoral bypass method in distal arteries when needed. Arteriotomies were closed surgically at the end of the procedure and the patients were transferred to the floor for follow-up.

Endovascular treatment using fenestrated and branched stent grafts is not performed in our hospital, as the use of such grafts is limited to research and training hospitals and university hospitals in accordance with the policies of our country’s Ministry of Health. Therefore, we did not use a fenestrated or branched graft in any patient.

Follow-up

All patients were followed, with CT angiography conducted at one, six, and 12 months and annually thereafter. Patients’ creatinine values were checked before and after the procedure.

Results

The mean age of the patients who underwent endovascular repair due to IDAA was 60.3 ± 9.9 (range, 42–72) years. All patients had histories of hypertension and had been receiving at least two antihypertensive drugs. Eight patients were active smokers. The mean diameter of the abdominal aorta was 46.7 ± 20.6 (range, 31.2–100.9) mm, the mean aortic neck diameter was 23.3 ± 3.5 (range, 19.2–30.2) mm, the mean diameter of the right common iliac artery was 13.8 ± 2.2 (range, 11.4–17.7) mm, and the mean diameter of the left common iliac artery was 15.1 ± 2.8 (range, 10.7–19.1) mm.

The dissection flap extended to the proximal aortic neck in two (18.1%) patients, and the left renal artery was at risk in one of these patients. Distally, abdominal dissection was associated with the right iliac artery in four (36.3%) patients and with the left iliac artery in three (27.2%) patients. The dissection did not extend to the external iliac artery in any patient.

The mean length of dissection was 71.1 ± 47.3 (range, 17–162) mm in patients who had undergone endovascular treatment. The dissection extended over the renal arteries in one patient and up to the level of the renal artery in two patients. In the remaining eight patients, the dissection began inferior to the renal arteries. The mean distance between the lowest renal artery and the dissection was 50.4 ± 25.2 (range, 15–99) mm in cases in which the dissection began inferior to the renal artery.

Early period

Aorto-iliac stent graft implantation was performed successfully in all but one (90.9%) patient. No tubular stent graft was inserted in any patient, as dissections extended to the terminal aorta level in all patients. Compression-related total occlusion occurred in the contralateral stump of the aorto-iliac stent graft due to 120° angulation in the neck region of the aorta in one patient (Figure 1).

Figure 1.

Scattered preoperative axial computed tomography angiography images obtained at above coeliac artery level (a), renal arteries level (b), and infrarenal level (c) show isolated abdominal aortic dissection flap as well as infrarenal abdominal aortic aneurysm. Multiplanar reformatted image (d) shows high aortic neck angulation (arrow).

We attempted to proceed past the contralateral stump occlusion from the femoral and brachial arteries using diagnostic catheters with different end structures; however, this could not be achieved. Hence, an iliac extension, the distal end of which was 12 mm in diameter, was inserted into the left common iliac artery (diameter, 18 mm) in which the contralateral leg would be placed. An Amplatzer vascular plug (AGA Medical, Golden Valley, MN) with a diameter of 16 mm was then inserted. Thus, filling of the dissecting aortic aneurysm from the contralateral iliac artery was hindered. This patient underwent femoral–femoral bypass with an 8-mm ring and vascular PTFE graft in the same session. The dissection flap extended to the aortic neck region in the same patient. The 18-mm Amplatzer vascular plug (AGA Medical) that had been inserted into the false lumen of the aortic neck hindered compression of the stent graft onto the false lumen and supported the false lumen. In addition, this plug prevented potential filling of the false lumen from proximal leakage in the dissection flap, which could not be visualized.

No complication, such as mortality or rupture, was observed during the procedures and no open surgery was required. Proximal type-1 leakage was observed in four patients for whom control angiography was performed following stent graft insertion, and aortic balloon dilatation was applied in these patients, as the dissection did not extend to the neck part of the flap. Leakage was prevented with balloon dilatation in three patients in whom the main body could be placed correctly just inferior to the renal arteries. Proximal leakage was prevented using an aortic extension, as leakage continued in one patient in whom the main body could not be placed close to the renal arteries during the procedure. Thus, no angiographic leakage was occurring in any patient at the end of the procedure. Tomographic angiography also showed no abnormal or false lumen filling in any patient.

In one patient in whom the dissection flap extended to the left renal artery, the stent graft was placed such that it began just above the left renal artery to preserve it, and the chimney technique was applied to the left renal artery concurrently by placement of a coated stent (Viabahn; W.L. Gore & Associates) measuring 6 × 50 mm. No leakage was detected on diagnostic angiography following the procedure in this patient.

No patient required blood transfusion, and no case of contrast medium toxicity or renal dysfunction occurred. All patients were followed at the cardiovascular surgery clinic, with no need for follow-up in the intensive care unit. No systemic complication was observed in patients who underwent the procedure.

Late period

The mean duration of follow-up was 25.5 ± 17.1 (range, 6–60) months in patients who underwent endovascular surgery. Four (36.3%) patients could be reached for follow-up at two years or longer after the procedure and five (45.4%) patients could be reached at one year or longer; complications such as leakage and graft thrombosis were detected. On follow-up, the grafts of patients who had undergone graft placement using the chimney technique and femoral–femoral bypass were found to be patent. No filling was detected in stump-related aneurysms on control CT angiography performed six months after the procedure in the patient whose contralateral leg stump was obliterated due to compression (Figure 2).

Figure 2.

Three-dimensional volume-rendered reformatted images (a, b) obtained at the postoperative sixth month show occlusion of the contralateral stump of the bifurcated aortic body due to high aortic angulation (a; arrow), iliac occlusion by using iliac tubular stent-graft and amplatzer vascular plug (a and b; arrowhead) to hamper type-II endoleak, and right-to-left femoral bypass graft (a; curved arrow) to maintain left leg arterial supply. Also, an amplatzer vascular plug (b; arrow) shows outside the true lumen, within the false lumen at the level of the aortic neck.

This patient is being closely monitored for leakage with Doppler ultrasonography every three months.

Discussion

Aortic dissection involves dehiscence of the layers of the aortic wall. Dissection affects blood flow in the true aortic lumen and branching collaterals, and may lead to malperfusion and ischemia in vital organs or the extremities due to reduced blood flow.⁴ Aortic rupture is a fatal complication of aortic dissection.⁵ Hypertension was determined to coexist in 80% of patients who had undergone surgery due to aortic dissection.⁶ All patients in the present study had hypertension.

IDAA is the rarest type of dissection; it was detected in only 10 of 398 (2.5%) patients in a previous study.⁷ In our study, the rate of IDAA among treated aortic pathologies was 3.5%. As in our study, abdominal pain is the most commonly reported symptom of abdominal dissection. However, patients may present with visceral or lower extremity ischemia or acute renal failure.⁸ Aortic rupture was reported in 28% of patients with IDAA, and a risk of mortality was reported in 90%.⁷ Contrast-mediated abdominal CT is the most important diagnostic tool for evaluation of this condition. The left iliac artery is more commonly affected than the right iliac artery, as the false lumen usually descends from left of the aorta in the dissection. The left renal artery is usually located in the false lumen, and it may consequently narrow or become completely occluded.⁹ In the present study, abdominal aorta dissection affected the right iliac artery in four patients and the left iliac artery in three patients. The left renal artery was compressed by the false lumen in one patient. The dissection extensions were treated completely in all patients.

The indications for treatment include unresponsive pain, lower extremity ischemia, aneurysm (>3 cm), visceral malperfusion, and rupture.⁷ Considering the high risk of rupture due to dissection, aortic repair is recommended in all patients with aortic diameters > 3 cm.⁷

In symptomatic patients without coexisting aortic aneurysm, pain should be treated with analgesics and arterial hypertension should be treated with antihypertensive drugs. However, early invasive treatment is recommended in the presence of coexisting abdominal aortic aneurysm, even in cases in which the IDAA diameter is <5 cm.¹⁰ In the present study, the aortic diameter was 3 cm in all patients with abdominal pain, and these patients were resistant to treatment. Although data on the occurrence of aortic dilation as a result of dissection are lacking, the coexistence of abdominal dissection and dilatation is a risk factor for rupture and an indication for treatment.^7,11

Surgical treatment of IDAA is accompanied by significant rates of in-hospital mortality (4%) and complications (9%).³ As for other aortic pathologies, endovascular aortic repair has been performed more frequently than surgery in recent years. However, endovascular aortic stent-graft procedures should be performed meticulously due to the fragility of the vessel wall. The most critical point of the procedure is discrimination of the true lumen. Due to the rarity of IDAA, data regarding the optimal approach to the disease are scarce. In a meta-analysis of 92 patients with abdominal aorta dissection, Jonker et al.³ reported that endovascular treatment was associated with lower mortality and major complication rates than were surgical and conservative treatments.

Kouvelos et al.¹² reported on endovascular treatment outcomes in 14 patients with IDAA; the success rate was 90.9% after 32.5 months of follow-up. Jawadi et al.¹⁰ reported a success rate of 95% after a mean follow-up period of 67 months in 21 patients with IDAA who had undergone endovascular aortic repair. The chimney method, in which the stent is also inserted into the renal arteries in renal artery–related dissection, is a less complicated procedure than surgery. We successfully inserted a coated stent into the left renal artery using the chimney method in one patient whose left renal artery had narrowed due to the dissection flap.

Conclusion

Based on the data reported here, we consider that IDAA is a condition requiring intervention at an early stage, rather than follow-up, considering the more serious problems that could develop in the future. Endovascular intervention is preferable to surgery due to the low mortality and morbidity risks. Our results support those of the few previous reports regarding this condition in the literature.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

References

Shennan

Dissecting aneurysm. Medical Research Council Special Report, Series No. 193, 2nd ed. His Majesty's Stationery Office, London, 1934.

Robberts

and Roberts

WC.

Aortic dissection with the entrance tear in the abdominal aorta. Am Heart J 1991; 121: 1834.

Jonker

Schlösser

Moll

et al . Dissection of the abdominal aorta. Current evidence and implications for treatment strategies a rewiew and meta-analysis of 92 patients. J Endovasc Ther 2009; 16: 71–80.

Robbins

Mc Manus

Mitchell

et al.

Management of patients with intramural hematoma of the thoracic aorta. Circulation 1993; 88: 1.

Peter

Hagan

Christoph

et al . The International Registry of Acute Aortic Dissection (IRAD) new insights into an old disease. JAMA 2000; 283: 897–903.

Bakey

Mc Collum

Crawford

et al.

Dissection and dissecting aneurysms of the aorta: twenty-year follow-up of five hundred twenty-seven patients treated surgically. Surgery 1982; 92: 1118.

Farber

Wagner

Cosmann

et al . Isolated dissection of the abdominal aorta: clinical presentation and therapeutic options. J Vasc Surg 2002; 36: 205–210.

Trimarchi

Tsai

Eagle

et al . Acute abdominal aortic dissection: insight from the ınternational registry of acute aortic dissection (IRAD). J Vasc Surg 2007; 45: 1087.

Buket

Atay

Calkavur

et al.

Aortic dissections. Aortic Surg 2003;

: 199.

10.

Jawadi

Bisdas

Torsello

et al . Endovascular treatment of ısolated abdominal aortic dissection: long-term results. J Endovasc Ther 2014; 21: 324–328.

11.

Graham

Alexander

Franceschi

et al . The management of localized abdominal aortic dissections. J Vasc Surg 1988; 8: 582–591.

12.

Kouvelos

Vourliotakis

Arnaoutoglou

et al . Endovascular treatment for isolated acute abdominal aortic dissection. J Vasc Surg 2013; 58: 1505–1511.