HYPOTHERMIC BYPASS AND CIRCULATORY ARREST FOR OPERATIONS ON THE DESCENDING THORACIC AND THORACOABDOMINAL AORTA

Background. Hypothermic cardiopulmonary bypass with intervals of circu latory arrest is a useful adjunct during operations on the descending thoracic aorta and distal aortic arch when severe aortic disease precl udes placement of clamps on the aorta. Hypothermia also has a marked p rotective effect on spinal cord function during periods of aortic occl usion. Methods. Fifty-one patients (age range, 22 to 79 years) with de scending thoracic or thoracoabdominal aortic disease had resection and graft replacement of the diseased aortic segments using hypothermic c ardiopulmonary bypass and intervals of circulatory arrest in situation s where the location, extent, or severity of disease precluded placeme nt of clamps on the proximal aorta (8 patients) or (in 43 patients) wh en extensive thoracic (11) or thoracoabdominal (32) aortic disease was present and the risk for development of spinal cord ischemic injury a nd renal failure was judged to be increased. Patent intercostal (below T-6) and upper lumbar arteries were attached to the graft whenever po ssible. Results. Thirty-day mortality was 9.8% (5 patients). Paraplegi a occurred in 2 and paraparesis in 1 of the 46 30-day survivors (6.5%) . Among the 27 operative survivors with thoracoabdominal aneurysms, pa raplegia occurred in 1 of 12 with Crawford type I (8%), 0 of 10 with t ype II, and 1 of 5 with type III aneurysms (20%). Paraplegia occurred in none of the 12 patients with aortic dissection and in 2 of the 15 p atients with degenerative aneurysms. Renal failure requiring dialysis occurred in 1 (2.2%) of the 46 30-day survivors. Conclusions. Hypother mic circulatory arrest is a valuable adjunct for the treatment of comp lex aortic disease involving the aortic arch and thoracoabdominal aort a. In patients with thoracoabdominal aneurysms, its use has been assoc iated with a low incidence of renal failure and an incidence of parapl egia/paraparesis in traditionally high-risk subsets (type I and II ane urysms, aortic dissection), which may be less than that observed with other surgical techniques.