Effects of cardiopulmonary bypass surgery on coronary flow in children assessed with transthoracic Doppler echocardiography

Abstract

Aburawi EH, Berg A, Liuba P, Pesonen E. Effects of cardiopulmonary bypass surgery on coronary flow in children assessed with transthoracic Doppler echocardiography. Am J Physiol Heart Circ Physiol 293: H1138-H1143, 2007. First published May 4, 2007; doi:10.1152/ajpheart.00025.2007.-Perturbation of coronary blood flow (CF) is an important contributor to myocardium-related complications. The study was primarily designed to assess the impact of cardiopulmonary bypass (CPB) surgery on CF by aid of transthoracic Doppler echocardiography. Changes in CF after off-pump coarctation surgery were also studied. All ultrasounds were performed before and 5 Ϯ 1 days after surgery. Eighteen children underwent CPB surgery of ventricular left-to-right shunts at the mean age of 6 mo, while off-pump surgery (aortic coarctectomy) was undertaken at the mean age of 10 days in 12 children. After CPB surgery, both left anterior descending coronary artery mean diameter and basal CF increased from 1.7 Ϯ 0.3 to 2.1 Ϯ 0.4 mm (P ϭ 0.001) and 27 Ϯ 10 to 47 Ϯ 15 ml/min (P ϭ 0.0001), respectively. These two coronary variables decreased after off-pump coarctectomy: left anterior descending coronary artery mean diameter from 1.8 Ϯ 0.1 to 1.7 Ϯ 0.1 mm (P ϭ 0.06), and CF from 44 Ϯ 12 to 25 Ϯ 8 ml/min (P ϭ 0.001). The findings are in keeping with the hypothesis that the previously reported impairment of coronary flow reserve after CPB surgery could be due to increase in basal coronary flow after CPB. Off-pump coarctectomy seems to have little impact on CF, as the postsurgical decline in flow in these patients seems to relate to the reduction in cardiac pressure afterload. congenital heart disease; coronary blood flow; cardiopulmonary bypass surgery PERTURBATION OF CORONARY BLOOD flow (CF) is an important contributor to myocardium-related complications, such as contractile dysfunction and arrhythmias (14), which sometimes appear during the first week after cardiac surgery on cardiopulmonary bypass (CPB). Coronary flow reserve (CFR) after CPB surgery has been reported to be decreased (7), but the precise pathophysiology remains debatable.Congenital heart diseases cause several hemodynamic and functional changes that are likely to affect CF. Reduced arterial oxygen saturation, myocardial hypertrophy, increased heart rate, and volume and pressure overload contribute to myocardial oxygen deprivation and CF (8,17,18,22). Oxygen demand regulates coronary flow. The major determinants of the oxygen demand of the myocardium are heart rate, contractility, and wall stress. Wall stress is related to ventricular pressure, chamber diameter, and wall thickness (10). Myocardial oxygen demand is described as rate-pressure product (RPP), the product of heart rate and mean systolic blood pressure (2). The maximal ability of coronary circulation to increase in response to increased cardiac metabolic demand is referred to as CFR. CFR is commonly expressed as the ratio of maximal coronary flow (e.g., by adenosine infusion) to basal flow (5, 15, 16). CPB, together with ca...

Pathophysiology of coronary blood flow in congenital heart disease

“…Accuracy Endothelial vasoactivity has been shown to correlate inversely with CRP in patients with CRP levels up to 45 μg/ml (22). As we showed earlier, CF increases after cardiopulmonary bypass (14,23), but this increase is blunted when CRP is elevated, particularly among patients in whom aortic clamping lasted for more than 1 hour. A similar negative association was seen in CoA patients from this series (6).…”

Coronary flow before and after surgical versus device closure of atrial septal defect

“…Because arteries have a certain maximal dilatory state they can reach, the increased basal flow after surgery leads to the decrease of CFR as reported earlier [2]. Our earlier work [3] showing the increased coronary BF after surgery for ventricular septal defect and atrioventricular septal defect and decreased BF after coarctation of aorta operations can be criticized because the diagnostic groups as well as the age of the patients were not similar. In the present study these aspects are taken into account.…”

“…The reported decrease of coronary flow reserve (CFR) after surgery with cardiopulmonary bypass (CPB) [2] might be due to increased coronary flow after the surgery [2,3]. CFR reflects the ability of coronary circulation to increase in response to increased cardiac metabolic demand.…”

Coronary Blood Flow by Transthoracic Echocardiography in Children with Endomyocardial Fibrosis

“…Peak flow velocity in diastole (PFVd), velocity time integral in systole and diastole (VTIs+d) and CF were measured in both the left anterior descending (LAD) and posterior descending (PD) coronary arteries as previously described (1). CF was calculated as follows: CF (ml/min) = VTIs+d x Heart rate x π (coronary radius) 2 .…”