A transthoracic Doppler echocardiography study of C-reactive protein and coronary microcirculation in children after open heart surgery

Background: Systemic inflammation has been suggested to underlie in part the elevated risk of arrhythmias and myocardial dysfunction during the first weeks after cardiac surgery. Recent transthoracic Doppler studies from our centre indicated increased basal coronary arterial flow in children 5 days after cardiopulmonary bypass surgery. In these children, we investigated whether the inflammatory mediator, C-reactive protein, could influence this association. Methods: The peak flow velocity, velocity time-integral in diastole and systole, and basal blood flow in the proximal part of the left anterior descending artery, were assessed by transthoracic Doppler echocardiography 1 day before, and 5 days after, cardiac surgery in 17 children with ventricular and atrioventricular septal defects whose mean age at surgery was 6 months. Levels of C-reactive protein in the plasma were measured at both time-points. Results: Prior to surgery, all children had levels of C-reactive protein under the limit for detection, that is less than 0.8 milligrams per litre. The levels of the protein had increased significantly by the second day, when the median value was 25, and the range from 20 to 142 milligrams per litre. They remained elevated on the fifth day after surgery, when the median was 11, and the range from 3 to 20 milligrams per litre. On the fifth day, the percentage increase in velocity time integral corrected for left ventricular mass was significantly lower in those patients with C-reactive protein greater than or equal to 10 milligrams per litre than in the remaining patients. Also, both the velocity time integral and the velocity of diastolic peak flow correlated inversely with log C-reactive protein, r being equal to -0.54 and p less than 0.02 and r equal to -0.74 and p less than 0.01, respectively, particularly among those patients in whom clamping of the aorta lasted for more than I hour, r for this statistic being equal to -0.8. Conclusion: The postsurgical increase in the velocity of coronary arterial flow in children is inversely associated with rising levels of C-reactive protein. The duration of the aortic cross-clamping during surgery strengthens the association between levels of C-reactive protein and the microcirculatory changes.