All patients with abdominal or thoraco-abdominal aneurysms treated at the Vascular Service of the University of Natal were reviewed. Aneurysms extended above the renal arteries in 15 % of patients (140 patients), of these 71 originated in the thoracic aorta. The aneurysms were resected or excluded and the diseased aorta and major branches reconstituted with prosthetic grafts, through bilateral subcostal or eighth interspace thoraco-abdominal incisions. Local 4ï¿½C hypothermic Ringer's lactate infusions into the renal, coeliac and superior mesenteric arteries were used for visceral organ protection. In addition, intravascular mannitol, calcium channel blockers, steroids, anti-endotoxin serum and intrathecal papaverine with cerebrospinal fluid drainage were introduced during the period of review.
Between January 1980 and July 1993, 59 patients aged 8 - 66 years were treated for isolated aortic root and ascending aorta disease. The main indications for treatment were ascending aorta aneurysm (14 patients), ascending aortic dissection (7 patients), annulo-aortic ectasia (15 patients), combined ascending aorta and aortic valve disease (11 patients), congenital hypoplastic aortic root (4 patients), infected aortic root (3 patients) and calcified aortic root (5 patients). One patient (1,63%) had previous ventricular septal defect closure and aortic valvotomy. Concomitant cardiac procedures were performed in 14 patients (23,73%).
Descending thoracic aortic surgery is invariably associated with a risk of paraplegia. Spinal cord ischaemia occurs as a result of intra-operative systemic hypotension, occlusion or hypoperfusion of a major radicular artery or from increased cerebrospinal fluid pressure. The risk of causing spinal cord ischaemia is modified by the underlying pathological process. Hence, the incidence of paraplegia complicating surgery varies from 0,4% after aortic coarctation repair to 30% after aortic replacement for type II thoraco-abdominal aneurysm. Various peri-operative techniques can be used to diminish the risk of paraplegia in identifiable high-risk patients or groups.
Neurological injury is the most feared complication of thoracic aortic surgery and is devastating in its consequences. There can be little doubt that over the last 10 years there has been a dramatic reduction in risk of brain damage because of refinement in technique and protective measures. Unfortunately, this complication still occurs sporadically and often unpredictably and continues to cause death and serious disability. A comprehensive review of all aetiological and protective aspects is outside the scope of the present review. The following distinct aspects merit discussion.