Neurologic sequelae of deep hypothermic circulatory arrest in cardiac transplant infants

Background. 1. Considerable controversy exists experimentally and clinically regarding adverse neurologic effects that may follow deep hypothermic circulatory arrest. Moreover, the techniques of DHCA have never been standardized. Methods. We prospectively studied the neurodevelopmental outcome in 38 infants undergoing cardiac transplantation using DHCA before the age of 4 months (mean age, 37.0 days). Neurodevelopmental outcome in the 22 boys and 16 girls was tested up to 2.5 years after transplantation using the Bayley scales of infant development. Bayley scores were compared with the rate of core cooling and the length of DHCA in all patients. Deep hypothermic circulatory arrest was accomplished using an asanguineous prime resulting in hematocrits of 5% ± 5% and ionized Ca²⁺, 0.4 ± 0.1 mmol/L. No surface precooling was used, but the head was packed in ice. Mean core cooling time was 14.0 ± 3.5 minutes, resulting in rectal temperatures of 18° ± 2.5°C. Duration of DHCA ranged from 42 to 70 minutes (mean duration, 56.0 ± 6.6 minutes). Results. Postoperatively, the mean Bayley psychomotor development index was 91 (range, 50 to 130) and mental developmental index was 88 (range, 50 to 130). No relationship was found between either the rate of cooling or the duration of DHCA and the Bayley scores (r = 0.227 and r = 0.322, respectively). Conclusions. These data suggest that neither the rate of cooling nor DHCA times between 42 and 70 minutes using profoundly low hematocrits and low ionized calcium levels has any measurable effect on neurologic outcome up to 2.5 years postoperatively. It is possible that adverse neurologic outcomes from DHCA reflect particular methods of achieving DHCA.