Spontaneous infrarenal abdominal aortic dissection: case report and literature review
(Portuguese PDF version)

Newton de Barros Jr.,1Jorge Eduardo de Amorim,1 Maria del Carmen Janeiro Perez,1 Fausto Miranda Jr.2

1. Ph.D. Adjunct professor. Vascular Surgery Discipline, Department of Surgery, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP-EPM), São Paulo, Brazil.
2. Associate professor and chief of the discipline of Vascular Surgery, Department of Surgery, UNIFESP-EPM, São Paulo, Brazil.

Correspondence:
Newton de Barros Jr.
Rua Coronel Lisboa, 690, Vila Clementino
CEP 04020-041 - São Paulo, SP, Brazil
Phone: +55 (11) 5572.4429
Fax: +55 (11) 5579.9814
E-mail: nbarrosj@uol.com.br

ABSTRACT

Spontaneous infrarenal abdominal aortic dissection is a rare disease that may present with abdominal or back pain, sometimes causing lower extremity ischemia, nevertheless, it can also be asymptomatic. We describe a case of a hypertensive, 47 year-old female with acute onset of back, groin and abdominal pain, lasting two months. At the beginning of symptoms, spontaneous infrarenal abdominal aortic dissection was detected by ultrasound and computerized tomography. There were no associated leg ischemia or rupture signs. We compare the clinical features with the literature.

Key-words: aorta, dissection, aneurysm.

J Vasc Br 2004;3(4):379-82

Spontaneous infrarenal abdominal aortic dissection (SIAAD) is rare as compared to the frequency of thoracic aortic dissections.¹ A review of the English literature found 52 published cases between 1953 and 2003.² Causes can be iatrogenic, traumatic and spontaneous. The most common symptoms are abdominal pain or lower limb ischemia, and only a small portion of patients remains asymptomatic.

CASE REPORTS

A 47-year-old smoker with mild hypertension presented in another healthcare service with sudden acute pain in the groin radiating to the left and right loins. After 6 hours of the symptoms onset, the pain radiated to the right portion of the abdomen and the patient developed nausea and an intense discomfort. An upper digestive endoscopy revealed peptic ulcers (two) in the duodenum, and the abdominal ultrasound detected chronic acalculous cholecystopathy and double lumen of the abdominal aorta (Figure 1). Arterial pressure was 180 x 120 mmHg. The patient was submitted to computed tomographic scans of thorax, abdomen and pelvis, which confirmed the dissection of the infrarenal abdominal aorta with false lumen in the right common iliac artery, with no signs of hematoma or mural thrombi (Figure 2). The patient was discharged after 2 days with intermittent abdominal pain, intense meteorism and constipation. She decided then to look for another medical service.

Figure 1 - Ultrasound image of the double aortic lumen. Longitudinal section (on the left) and transversal section (on the right).

Figure 2 - Abdominal computed tomography scan showing the infrarenal abdominal aortic dissection.

After 40 days of the symptoms onset, the patient presented the same diffuse and intermittent abdominal pain, meteorism and constipation. The physical examination did not reveal pulsatile masses or abdominal murmurs. Arterial pulses were present and normal from the aorta to the distal arteries. The brachial-ankle index was normal in both lower limbs. Another computed tomographic scan was required, which revealed the absence of aortic dissection and aneurysmal vessels with false lumen thrombosis (Figure 3). It was possible to see the image of a small ulcerous portion in the right common iliac artery (Figure 4).

Figure 3 - Tomographic control performed 42 days after the previous tomographic scan at the same section, but without the presence of the false

Figure 4 - Tomographic image showing the abdominal aorta with normal caliber, without the false lumen, assembled with the image of a small indentation originated in the left common iliac artery.

The patient is currently found with no abdominal or back pain, although she is still with meteorism and light constipation. Hypertension is under control with the administration of low dose betablockers (atenolol). The peptic disease is being treated with specific drugs (pantoprazole).

DISCUSSION

In most of cases, the abdominal aortic dissection occurs as a consequence of the extension of thoracic aortic dissections.^3,4 The SIAAD is a rare disease. So far, only 52 cases have been reported in the English literature.²

Thoracic aortic dissection may be caused by trauma, pregnancy, hereditary connective-tissue disorders (Marfan's Syndrome and Ehler-Danlos Syndrome) and lack of alpha-1-antitrypsin;⁵ however, The etiology of abdominal aortic dissection is still unclear, but it can be classified as traumatic (blunt abdominal trauma), iatrogenic and spontaneous.^1,2 Atheromatosis of abdominal aorta has been frequently observed in surgeries of spontaneous dissection of the infrarenal abdominal aorta, but its role in the event of dissection is controversial. There are reports of the presence of Takayasu arteritis and even infection by the virus of hepatitis C in excised tissues. The association of these diseases with dissection, however, is not proved to be true.⁶

Systemic arterial hypertension seems to be associated mainly with the thoracic aortic dissection (60-70% of cases) as compared to the abdominal aortic dissection (50% of cases).

Patients with infrarenal abdominal aortic dissections are classified intro three groups: asymptomatic - diagnose performed with imaging tests, they account for 25% of cases; with pain (almost 60% of cases) - developing abdominal or back pain; and ischemic - developing lower limb ischemia as a result of acute arterial occlusion or intermittent claudication (15% of cases).

In the last review of the most comprehensive series already published,² the disease was most frequent in men (66% of cases) than in women, and the mean age was 60 years. Half of them presented arterial hypertension and had the dissection process extended into the lower limb arteries. Rupture is very frequent. It was present in 17% of patients (nine), and the hemorrhagic shock was the most frequent sign (66.6%). Four deaths were associated with the dissection rupture (7.7%) and two had no association. Thirty-eight patients were treated with classical surgery, three with endovascular surgery and nine with clinical observation alone.

Intermittent claudication of lower limbs is more frequent in thoracic aortic dissections, especially DeBakey type III³ and Stanford type B.⁷ This finding is rare in SIAAD; only five cases presented with this symptom.

The most frequent location of SIAAD is between the renal artery and the inferior mesentery artery.⁸ In around 50% of cases, the distal extension of the dissection is constrained to the aortic segment. The other 50% are affected in the iliac-femoral segment, developing distal acute ischemia resultant from mechanical obstruction of the lower extremities perfusion.

The SIAAD is responsible for aneurysms formation in a significant number of patients (40%). The same way as it happens in the thoracic aortic dissection, the chronic dissection may evolve to aneurysmal degeneration³ because the aortic wall becomes weaker, increasing the risk of rupture. In general, rupture takes place at the point where dissection joins the normal aortic wall, and during these events, the risk of death is increased, reaching 90%.²

In the case reported here, there was no aneurysmal formation, rupture or hematoma, probably because of the short time of evolution. A long-term follow-up is required for the identification of any abnormal behavior.

Our patients were approached with the conventional surgical treatment.² Most of them had their aorta and/or iliac segment replaced by a tubular or bifurcated Dacron prosthesis, although there are cases of patients managed successfully with endovascular surgery.^2,9

Treatment of acute thoracic aortic dissections with covered stents has presented good technical and clinical outcomes, especially in type B dissections.^7,8 In SIAADs, the endovascular treatment have been used in isolated cases,^1,8,10,11 and, sometimes, guided by intravascular ultrasound.¹¹ This type of approach remains a challenge in acute cases, because of the abdominal aortic caliber, the dissection extension toward the iliac arteries and the compression of the true lumen by the false lumen.

The classic indications for surgical treatment are aortic rupture, lower limb ischemia, untreatable pain, development of aneurysm and degeneration of the false lumen.² The rupture of the dissection must be approached urgently.

Patients with abdominal pain should be examined carefully, so that other diseases can be ruled out. If no other cause of symptoms was found and pain persists, the aorta should be repaired. In our case, the initial symptoms could be associated with dissection, however, the development of abdominal pain, meteorism and constipation were probably associated with gastric and biliary pathologies, as the visceral arteries were not involved in dissection and there was no symptom of mesenteric ischemia or retroperitoneal hematoma.

Patients with extremities ischemia should be managed with open or endovascular surgery, and this decision should be based on the operative risk, size and morphology of arteries. The patients who develop aneurysms should be operated because of the risk of rupture.

Eventually, asymptomatic patients should be treated with anti-hypertensive drugs and monitored periodically with tomographic scans or magnetic resonance.

In the case reported here, the abdominal pain was controlled; dissection remission was spontaneous and only a failure in the vessel filling remained in the origin of the right iliac artery. This patient will be submitted to repeated imaging studies to follow the progression or mural degeneration of the abdominal aorta. Different from the abdominal aortic atherosclerotic aneurysm, the maximum diameter of the aneurysm that would be indicated for surgical treatment was not established for the infrarenal aorta.

As a conclusion, we may say that the SIAAD is a rare disease that is found in multiple ways. In the case reported here, the dissection decreased spontaneously and pain relieved. Further assessment should be performed in the future in order to determine what the natural development of the disease is.

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