Direct optical measurement of intraoperative myocardial oxygenation during congenital heart surgery.

This study demonstrates use of novel technology to measure cellular oxygenation during corrective congenital heart surgery. Cellular oxygenation was measured using a custom-designed optical probe placed on the free wall of the right ventricle. Cellular oxygenation, determined from myoglobin saturation, was calculated using multiwavelength analysis. Timing of bypass, aortic cross-clamp, infusion of cardioplegic solution, and length of intensive care unit (ICU) stay were recorded. Baseline cellular oxygenation was approximately 50% just before aortic cross-clamp and decreased to approximately 20% during cardioplegia. Cellular oxygenation remained low throughout cardioplegia and returned toward baseline after bypass. In four cases, cellular oxygenation did not return as quickly to baseline as in the other three cases. Among the four patients demonstrating slow recovery, the average ICU length of stay was 2.25 days compared with an average stay of 1.33 days for those patients exhibiting rapid cellular oxygenation recovery (p = 0.06). The slow recovery group had an average cross-clamp time of 40.1 ± 28.4 minutes, compared with 26.0 ± 8.5 minutes for the fast recovery group (p = 0.34). This study demonstrates for the first time that myocyte cellular oxygenation can be measured intraoperatively during cardiac surgery. Measurement of cellular oxygenation may be useful for improving myocardial preservation techniques.

Minimizing bleeding associated with mechanical circulatory support following pediatric heart surgery.

OBJECTIVE: The use of extracorporeal membrane oxygenation (ECMO) to support patients with early postcardiotomy heart failure may be associated with catastrophic bleeding, making its use undesirable. However, postcardiotomy mechanical circulatory assistance is necessary in some patients to allow for myocardial recovery. We have assembled a centrifugal pump system (CPS) that does not require early systemic anticoagulation. This study compares postoperative bleeding in pediatric patients placed on standard ECMO versus CPS within 24h of cardiotomy. METHODS: Between November 2002 and February 2007, 25 patients (age 0 days-1.72 years) received postcardiotomy mechanical support. Fourteen patients were placed on ECMO and 11 patients were placed on CPS within 24h of surgical repair. Retrospective analysis was performed of chest-tube drainage at multiple time points following initiation of mechanical support. Additional variables, including Risk Adjustment for Congenital Heart Surgery-1 (RACHS-1) score, total time on mechanical support, 30-day mortality, activated clotting time, blood-product administration, circuit-related complications, and circuit changes were also analyzed. RESULTS: Patients on ECMO (0.30 ± 0.39 years) and CPS (0.40 ± 0.56 years) were of similar age (p = 0.64). Patients on ECMO (0.3 ± 0.1m(2)) and CPS (0.3 ± 0.1m(2)) had similar body surface areas (p = 0.46). Patients placed on CPS had significantly less chest-tube drainage during the first 4h of support. Activated clotting times appeared to be higher during the first 12h of ECMO versus CPS. There was no statistical difference between ECMO and CPS with respect to the following variables: RACHS-1 score, time on support, 30-day mortality, circuit-related complications, and circuit changes. Blood-product administration at 24h of support was significantly less (p = 0.04) for patients on CPS versus ECMO. CONCLUSIONS: Mechanical circulatory support can be provided without the complication of clinically significant bleeding if a specialized circuit is used. This has important implications for the decision to use mechanical support in the immediate postoperative period in the face of ventricular failure. In addition, early mechanical support can be used with a low incidence of circuit-related complications.