Abstract 126 Poster Session III, Monday, 5/3 (poster 132)

Pediatric cardiac surgery for congenital heart diseases may cause myocardial injury through 3 intraoperative mechanisms: 1.Ischemia during cardiopulmonary bypass (CPB) and cross-clamp (X-clamp), 2. Post-CPB reperfusion injury and 3. Myocardial incisions. Cardiac troponin 1 (cTnI), a subunit of troponin, is a specific and a sensitive marker for myocardial injury. The purpose of this study was to determine whether postoperative cTnI release is more reflective of direct myocardial injury through myomectomy/ventriculotomy (MYO) than through other types of myocardial injury.

METHODS: Twenty one consecutive patients ages 5.5 years ± 5.6 (mean ± SD) who consented to the study and underwent elective CPB formed the study cohort. Surgeries included Fontan (4), Bidirectional Glenn (1) and repair of atrial septal defect (4), ventricular septal defect (4), atrioventricular septal defect (3), tetralogy of Fallot (3), mitral and tricuspid valve (1).

6/21 patients had MYO. Blood was collected pre-CPB, immediately post-CPB and each post-op day (POD 1,2..). Serum levels of cTnI were measured by Microparticle Enzyme Immunoassay (MEIA) (Abbot, AxSYM system, IL, USA). RESULTS: The CPB 103 mins ± 63.4, X-Clamp 53.3 mins ± 45.5, CPB temperature (CPBT) 30.2 °C ± 3.8, ICU days 6.6 ± 4.1, and intubation days 1.14 ±0.6. The serum levels of cTnI in ng/mL were: pre-CPB= 0.19±0.2, post-CPB=50.5±62.5, POD 1= 28.3±31. The cTnI on POD 1(n=16) correlated with creatine kinase (r=0.7, p=.01), SGOT (r=0.8, p=.001), LDH (r=0.7, p=.01), ICU days (r=0.6, p=.02). In those with and without MYO, the cTnI post CPB and on POD 1 did not differ significantly. There was no difference in age, CPB, CPBT, X-Clamp or ICU days between those with and without MYO. In children ≤ 1 year age (5/21), the SGOT and post-CPB cTnI were higher (p=.05) than in older children, though there was no difference in CPB, X-Clamp, CPBT, or ICU days.

CONCLUSION: 1. The myocardial injury during cardiopulmonary bypass surgery seems to be independent of incisional injury to the ventricles 2. Myocardium of children ≤ 1 year maybe more vulnerable to damage from open heart surgery. 3. The greater the myocardial damage as reflected by cTnI levels, the longer the ICU stay.