[Cardiac troponin I after heart surgery corrective operation in infancy and childhood]

Perioperative myocardial damage is an important determinant for postoperative cardiac function and recovery. Cardiac troponin I (cTNI) is a specific marker for myocardial damage. The aim of our study was to evaluate pre- and postoperative cTNI levels, the pattern of elevation in the first four postoperative days and the prognostic value after pediatric cardiac operation.

Cardiac troponin I levels were measured in 115 children mean age 36 +/- 45 months (range 4 days to 189 months) undergoing elective operation of a congenital heart defect. Routine measurements were made preoperatively, immediately after cardiopulmonary bypass and serially 8, 18, 42, 90, 138 hours thereafter. Data from 13 patients undergoing surgery without cardiopulmonary bypass served as controls. Postoperative cTNI levels were correlated with intra- and postoperative parameters (such as duration of aortic crossclamping, cardiopulmonary bypass time and need for postoperative inotropic support).

All preoperative cTNI levels were in the normal range. Postoperatively, the highest median cTNI levels were found in patients after repair of tetralogy of Fallot (TOF), atrioventricular septal defect (AVSD) and implantation of a homo- or xenograft. Postoperative cTNI levels correlated significantly with duration of cardiopulmonary bypass and aortic crossclamping, operative approach (ventriculotomy versus atriotomy) and inotropic support (p < 0.0001). Peak cTNI levels were found immediately after surgery in 77.4% of our patients, 8 hours postoperative in 13.9% and at 18 hours after the surgery in 5.2% of the patients. In three children cTNI continued to increase; a secondary increase was found in one patient. Two of these children died, two had a prolonged postoperative recovery.

The postoperative level of cardiac troponin I could be used as a marker of perioperative myocardial injury caused by ischemia and operative trauma. Peak levels usually could be obtained immediately after surgery, but a further increase of cTNI during the following 18 hours may occur and is not necessarily related to impaired recovery. However still increasing cTNI levels after 18 hours postoperatively and a secondary increase as well may be used as indicators of poor outcome.