Spontaneous aortic rupture due to human immunodeficiency virus-associated vasculitis: A lesson learnt

Case description

We report a case of a 67-year-old male admitted to our services with a spontaneous contained rupture of the suprarenal abdominal aorta. Four months prior to his presentation to the vascular services, this gentleman was diagnosed with HIV and was subsequently reviewed by the infectious disease physicians. His CD4 count at that time was 128 (7.4%) and it was noted that he had had a reactivation of Herpes zoster suggestive of immunosuppression. It was thus decided to start him on highly active antiretroviral therapy (HAART) commencing with Combivir (lamivudine and zidovudine) and efavirenz. On routine screening, he was negative for both Hepatitis B and C; however, his venereal disease research laboratory serology test was positive, a diagnosis of latent syphilis was made and a course of benzylpenicillin was commenced.

Four months post-HIV diagnosis, he presented as an emergency admission with right upper and lower limb weakness, slurred speech and right facial droop. In the first week of that admission, he developed sudden severe lower back pain and worsening of his lower limb weakness. An MRI scan was performed demonstrating an infiltrating mass at the level of the juxtarenal aorta and thought initially to be consistent with an infiltrating Kaposi’s sarcoma. A CT angiogram was obtained and this confirmed the mass to be a suprarenal aortic haematoma with the aortic rupture site located immediately below the origin of the superior mesenteric artery and involving the aorta at the level of the right renal artery (Figure 1). OPEN IN VIEWER

He underwent an endovascular repair using a right renal chimney graft to extend the landing zone for an aortic exclusion graft. The aortic main body graft comprised a Talent™ (Medtronic, Santa Rosa, CA, USA) aortic extension graft (AXF3030W28AX: 30 mm × 28 mm). The right renal artery ‘chimney graft’ was a Viabahn™ (Gore Medical, Flagstaff, AZ, USA) endoprosthesis (PAH080502: 8 mm × 50 mm × 120 mm) deployed via the left brachial artery. The patient recovered well in the immediate post-operative period and was recommenced on antiretroviral therapy on the first post-operative day. Follow-up CT scan demonstrated that the aortic stent was in a good position with complete patency of the right renal artery stent (Figure 2). OPEN IN VIEWER

Two months later, he represented with pallor, diaphoresis and hypotension. CT angiogram confirmed aortic rupture below the previous stent. He underwent endovascular intervention, involving placement of two Powerlink (Endologix, Irvine, CA, USA) infrarenal aortic extension endografts (25-25-55 L: 25 mm × 25 mm × 55 mm and 34-34-80 L: 34 × 34 × 80 mm) overlapping with the previous stent. He recovered well from this procedure and his post-operative duplex scan on third post-operative day did not show any endoleak. On day 5 postoperatively, however, he had a further hypotensive episode and following discussion with the patient and his partner the decision was made that he would not be for further intervention. He passed away two days later.

Discussion

Vasculitis is an uncommon complication of HIV infection with an incidence of <1%. ¹ HIV is associated with a wide range of vasculitides; however, these predominantly involve the small- and medium-sized vessels. Large vessel involvement is extremely rare but cases of arteritis involving the common carotid artery, the aorta, the common iliac arteries and the femoral and popliteal arteries have been reported. ² In the case of our patient, the clinical picture is further complicated by a recent diagnosis of syphilis, which the infectious disease physicians had determined to be of a latent variety and had therefore left untreated. The characteristic histological appearance of vasculitis in HIV is of a leucocytoclastic vasculitis involving the vasa vasorum and the periadventitial vessels, although this appearance is not always present. ³ The mechanisms implicated in the pathogenesis of HIV-associated vasculitis include cell-mediated inflammation, immune complex-mediated inflammation and antibody-mediated inflammation. ⁴

Infective vasculitides in HIV are most commonly due to opportunistic infections such as Cytomegalovirus, Varicella zoster, Toxoplasma and Mycobacterium tuberculosis. These agents may cause vasculitis either due to direct microbial invasion or as a result of immune-mediated injury, as is seen in hypersensitivity vasculitis such as Henoch-Schonlein purpura and cryoglobulinaemia. ³ Hypersensitivity vasculitis can also be drug related with several antiretroviral agents implicated including zidovudine and didanosine. ⁵

One case reported in the literature was of a young HIV-positive male who died of an acute myocardial infarction in the absence of atherosclerotic disease. Immunohistochemistry of the affected arteries demonstrated changes consistent with Kawasaki-like syndrome. ⁶ Primary angitis of the central nervous system is a rare condition in HIV but with significant associated mortality. ^7,8 There is controversy regarding the relationship of HIV infection and stroke in young patients; however, a case control study by Qureshi et al. ⁹ found a statistically significant increase in the incidence of cerebral infarction in HIV-infected patients when compared with seronegative patients. They suggested that contributory aetiologies include increased susceptibility to meningitis and protein S deficiency.

A study of HIV-positive patients with large vessel disease by Chetty et al. ² identified a cohort of patients with large vessel disease in whom there was no evidence of atherosclerosis or thrombus and microbiological cultures of blood and vessel tissue were negative. Several of these patients did, however, show the characteristic leucocytoclastic vasculitis of the vasa vasoraand periadventitial vessels associated with HIV.

In addition to the specific cardiovascular sequelae of HIV infection, HAART itself has been associated with dyslipidaemia and premature atherogenesis. ¹⁰ Protease inhibitors in particular have been shown to cause dyslipidaemia and thereby promote atherosclerosis. The underlying mechanism by which this occurs has been related to increased CD36-dependent cholesteryl ester accumulation in macrophages. ¹¹ In a study by Maggi et al. ¹² , for example, an increased incidence in premature carotid lesions was demonstrated in patients treated with protease inhibitors. HAART has also been implicated in vasculitis as demonstrated by Domingo and Barcelo ¹³ relating efavirenz use to the development of a leucocytoclastic Vasculitis.

With improvements in antiretroviral therapy, the management of HIV-associated vascular disease will present novel challenges and it is also evident that further consideration needs to be given to the long-term sequelae of antiretroviral therapy and in particular to the atherogenic effects of protease inhibitors.