The impact of temperature in aortic arch surgery patients receiving antegrade cerebral perfusion for >30 minutes: How relevant is it really?

OBJECTIVE: We examined the early outcomes and the long-term survival associated with different degrees of hypothermia in patients who received antegrade cerebral perfusion (ACP) for >30 minutes. METHODS: During a 10-year period, 544 consecutive patients underwent proximal and total aortic arch surgery and received ACP for >30 minutes and 1 of 3 levels of hypothermia: deep (14.1°C-20°C; n = 116 [21.3%]), low-moderate (20.1°C-23.9°C; n = 262 [48.2%]), and high-moderate (24°C-28°C; n = 166 [30.5%]). A variable called "predicted temperature" was used in propensity-score analysis. Multivariate analysis was done to evaluate the effect of actual temperature on outcomes. RESULTS: The operative mortality rate was 12.5% (n = 68) overall and was 15.5%, 11.8%, and 11.5% in the deep, low-moderate, and high-moderate hypothermia patients, respectively (P = .54). The persistent stroke rate was 6.6% overall and 12.2%, 4.6%, and 6.0% in these 3 groups, respectively (P = .024 on univariate analysis). On multivariate analysis, actual temperature was not associated with mortality, but lower temperatures predicted persistent stroke and reoperation for bleeding. In the propensity-matched subgroups, the patients with predicted deep hypothermia had (nonsignificantly) greater rates of persistent stroke (12.2% vs 4.9%; relative risk, 1.08; 95% CI, 0.87-1.15) and reoperation for bleeding (14.6% vs 2.4%; relative risk, 1.14; 95% CI, 0.87-1.15) than the patients with predicted moderate hypothermia. On long-term follow-up (mean duration, 5.12 years), 4- and 8-year survival rates were 62.3% and 55.7% in the deep hypothermia group and 75.4% and 74.2% in the moderate hypothermia group (P = .0015). CONCLUSIONS: In proximal and arch operations involving ACP for >30 minutes, greater actual temperatures were associated with less stroke and reoperation for bleeding. There were no significant differences among the predicted hypothermia levels, although a trend toward a higher rate of adverse events was noticed in the deep hypothermia group. Long-term survival was better in the moderate hypothermia group.

Moderate hypothermia ≥24 and ≤28°C with hypothermic circulatory arrest for proximal aortic operations in patients with previous cardiac surgery.

OBJECTIVES: To determine whether, in patients with previous cardiac operations, moderate hypothermia (between 24 and 28°C) for hypothermic circulatory arrest (HCA) during antegrade cerebral perfusion (ACP) is safe for use during surgery on the proximal aorta and transverse aortic arch. METHODS: Over a 7-year period, 118 patients underwent ascending aortic and hemiarch repair (n = 70; 59.3%), total arch replacement (n = 47; 39.8%) or ascending aortic replacement to treat porcelain aorta (n = 1; 0.9%). Simultaneous procedures included aortic root repair or replacement (n = 33; 28.0%) and coronary artery bypass grafting (n = 21; 17.8%). All patients had previously undergone cardiac operations via a median sternotomy. Eighteen patients (15.3%) had more than 1 previous sternotomy, and 24 patients (20.3%) required emergent/urgent operation. Median cardiopulmonary bypass, cardiac ischaemic, circulatory arrest and ACP times (min) were 136.0 [118-180 interquartile range (IQR)], 91.0 (68-119 IQR), 34.0 (21-59 IQR) and 33.5 (20-59 IQR), respectively. The median temperature when HCA was initiated was 24.2°C (24.1-24.8°C IQR). RESULTS: The operative mortality rate was 10.2% (n = 12). Six patients (5.1%) had a permanent stroke, and 16 patients (13.6%) had a composite adverse outcome (operative mortality and/or a permanent neurological event and/or permanent haemodialysis at discharge). Preoperative renal disease was significantly more prevalent (P= 0.020) and the median circulatory arrest time significantly longer (48.5 vs 33 min; P= 0.058) in patients with composite adverse outcomes. Multivariable analysis of the redo patients showed that age (P =0.025), preoperative renal disease (P =0.024) and ACP time (P =0.012) were independent risk factors for a new postoperative renal injury. CONCLUSIONS: Moderate hypothermia for HCA during ACP is being used with increasing frequency, but has not been thoroughly evaluated in patients undergoing cardiovascular reoperations. Our experience suggests that in patients with previous cardiac surgery who are undergoing hemiarch and total aortic arch operations, moderate hypothermia is safe and produces respectable results.