Introduction

Congenital aortoiliac stenosis/occlusion or SAS was shown to induce peripheral obliterating arterial disease. Although it remains unclear whether SAS represents a separate entity, the small size of the distal aorta increases the risk for aortoiliac occlusive disease₁₂. The syndrome was characterized by infrarenal aortic diameter measuring less than 13.2 mm just below renal arteries, or an infrarenal aorta smaller than 10.3 mm just above the aortic bifurcation₃. Iliac and femoral vessels are typically correspondingly small in these patients, atherosclerotic changes occur in the lower aorta but the vessels below the iliac level, apart from being narrow, are relatively disease free. It has been described in females with a relatively early age of onset who are below average height and have smoked an average of 20 cigarettes per day for 20 years or more₄. The typical clinical presentation of this syndrome has been with bilateral buttock, thigh and calf claudication. Surgical treatment of these cases is challenging to surgeon and the preferred surgical method for reconstruction of the small aorta in symptomatic cases are still a debated issue. In this paper, we reported a case of SAS associated with occlusion of the lower part of the abdominal aorta and discussed the current literature knowledge about the etiology, the diagnosis and surgical management of this rare entity.

Case report

A 51-year-old woman presented with complaints of severe low back pain and pain radiating down the back of the legs into the soles of her feet after walking around distance of 100 meters. She had no history of ischemic rest pain in the past medical history and had smoked 20 cigarettes per day for 31 years. Physical examination revealed 160 cm slim lady who had a blood pressure of 140/85 mmHg. A systolic bruit was heard over the distal abdominal aorta. Both femoral pulses were poorly palpable with no pulses below. Heart sounds, respiratory sounds or neurological system were normal. The electrocardiogram and the chest roentgenogram did not demonstrate any sign of abnormality. Complete blood count, biochemical tests including electrolytes, liver function tests, creatinine and blood urea were all normal. Doppler studies showed bilateral ankle pressures of 70 mmHg with a brachial pressure of 140 mmHg (Ankle-brachial index: 0.5) and both femoral artery waveforms were markedly damped. Arteriography showed tapering of the lower abdominal aorta with a 90% stenosis just proximal to the bifurcation. Furthermore a gradual narrowing of the common iliac and femoral arteries was present (Figure 1).

Figure 1

Figure 1: Angiogram of case demonstrating the infrarenal aorta tapering in size with a 90% stenosis just proximal to the aortic bifurcation

There were neither thrombotic occlusions nor any atherosclerotic changes in the artery wall. These findings were compatible with the features of SAS. After all of these findings, operative treatment was planned for the patient.

The patient was placed under general anesthesia with arterial and central venous monitoring. After median laparatomy distal abdominal aorta was explored and encircled with silastic vessel loops. Before aortic cross clamping, the patient received systemic heparinization (100IU/kg) and intravenous mannitol to promote urinary diuresis. During the operation, the aorta was seen to taper down in size from the level of the renal arteries to the iliac bifurcation. Just proximal to the iliac bifurcation, there was marked localised stenosing arterial disease. The surgical procedure involved a local endarterectomy and the insertion of a Dacron patch (Hemashield, Meadox, Inc. Oakland, NJ) fashioned in the shape of an inverted “Y” (Figure 2). Early postoperative course was uneventful and the patient was discharged on the 7th postoperative day. After the operation, the resting doppler pressures in both ankles were normal and she was completely symptom free 6 months after surgery.

Figure 2

Figure 2: Postoperative Magnetic Resonance (MR) Angiography showing inverted “Y” dacron patchplasty of the aortic bifurcation.

Discussion

In 1969, Johnson suggested the term “Small Blood Vessel Syndrome” for young females presenting with symptomatic occlusive aorto-iliac disease₅. He noted that they were below average height, had mild truncal obesity, and had significant tapering of the infra-renal terminal aorta demonstrated by angiography. Greenhalgh and Taylor described a group of 27 females with an arterial disease confined to the terminal abdominal aorta, which tapered down in size to its bifurcation₆. They called these “little women with blocked aortas”, but later Greenhalgh adopted the term “Small Aorta syndrome”₄. Females in this group were young (mean age 49 years old) and normal endocrinologically and were noted to be below average height. In Johnson's series seventy eight percent had abnormal lipoprotein patterns with 70% having elevated serum cholesterol levels. He drew attention to the curious arteriographic finding of localised disease only at one site in the descending arterial tree. The peripheral arteries were in small size at whole budy completely disease free in other sites, although 30% had already had a myocardial infarction even at that early age₅.

Blood flow is an important determinant of hemostatic control; its relative deficiency may lead to local disruption of the integrity of the blood vessel and may underlie the tendency for thrombi to develop in restricted sites of the vasculature. For example, in this case SAS may have an important effect on vasculature of the lower limbs. SAS have been linked to a strong tendency toward arterial thrombosis and in this syndrome thromboses tend to recur. Surgical therapy is required, even if the duration and intensity of treatment remain controversial₅₆. Particularly, in a patient such as “in our case” the risk of recurrent thrombosis is higher and benefits of this therapy are greater than the risks.

Symptomatic peripheral vascular disease predominantly affects the male population. The incidence of peripheral vascular disease in young females is particularly low and may result from hormonal protection. In recent years a group of females who present at an early age with symptomatic aorto-iliac disease have been described₇. There are several risk factors that lead to the development of arterial disease in young women. Arnot and Louw suggest that a smaller diameter lower abdominal aorta is due to a congenital defect in which there is excessive fusion of the embryonic dorsal aortas around the 25[[[th]]] day of intrauterine life₈. Females in whom this occurs appear to have a higher risk of developing lower aortic occlusive disease. In addition, if they are small in stature, smoke for many years and suffer from a hyperlipidemic state, they are likely to develop symptomatic occlusive aorto-iliac disease at an early age.

In approximately 5% of patients with SAS, the infrarenal aorta, iliac, and femoral vessels are extremely small or hypoplastic, which causes aortic reconstruction technically difficult₉. Preferred surgical methods for reconstruction in patients with small vessels remain somewhat controversial; some authorities think the small size of the aorta and iliac vessels makes endarterectomy unsuitable, while others favoring bypass techniques advocate the use of end-to-side proximal aortic anastomosis to avoid size discrepancies with the usual prosthetic grafts₁₀. In our opinion because the disease in such patients is frequently localized, aortoiliac endarterectomy may often still be utilized. Although the small size of the vessels demands more care and occasionally requires the use of patch closures.

In this case, we performed an endarterectomy followed by dacron patch closure, which was fashioned in the shape of an inverted “Y”. A bifurcated dacron graft is sutured to both of the external iliac arteries when iliac arteries are involved in the disease proces. Many surgeons prefer end-to-side anastomosis technique to overcome size incompatibility between the graft and the native aorta. It is wise to choose a smaller sized graft to avoid the consequences of an oversized graft. Endarterectomy and patching with an appropriately sized inverted prostetic “Y”graft has become the procedure of our choice considering the aorto-iliac stenosis associated with intermittan claudication.

Conclusion

Overall, females with small aortic syndrome have higher risk of developing aortic occlusive disease. In addition, if they are small in stature, smoke for many years and suffer from a hyperlipidemic state, they are likely to develop symptomatic occlusive aorto-iliac disease at an early age. Patients, especially females, presenting in this way, require careful assessment of their vascular tree and may ultimately require the same arterial reconstruction used for those cases presenting with, thigh and calf claudication.

Correspondence to

Mert Dumantepe Address: Atıf bey sokak, Derya 85 sitesi 2. Kısım A blok, Kat: 3, D: 11, Acıbadem, 34660, ISTANBUL Tel: +90 216 5452858 Mob: +90 532 3771872 E-mail address: mdumantepe@gmail.com