Pathophysiology of coronary blood flow in congenital heart disease

Objectives: The aim was to investigate the effects of volume and pressure overload and increased coronary perfusion pressure on coronary flow (CF) in congenital heart disease (CHD) patients. Background: The effects of CHD on CF are poorly mapped. Methods: A total of 65 patients with acyanotic CHD and 49 age-matched healthy controls were examined by transthoracic Doppler echocardiography. Posterior descending artery flow was measured in patients with pulmonary valve stenosis (PS) and atrial septal defects (ASDs) i.e. in lesions with right ventricular pressure or volume overload, and left anterior descending artery flow in patients with coarctation of the aorta (CoA) and ventricular septal defect (VSD), in lesions with left ventricular pressure or volume overload. The CF data in each patient group were expressed as the percent of the median for healthy controls from the same age group. Results: The CF values were in VSD 172%, ASD 185%, PS 233%, and CoA 773% patients. In CoA patients body surface area (r = 0.90, p < 0.0001), systolic blood pressure (r = 0.72, p < 0.0001), diastolic blood pressure (r = 0.77, p < 0.0001), systolic wall tension (r = -0.77, p = 0.004), and signs of inflammation (log CRP, r = -0.75, p = 0.007) correlated with CF. Conclusions: The increase in CF and velocity was most significant in patients with CoA. In newborns, increased coronary perfusion pressure seems to be the most important factor for increased CF, even if the pressure is not assumed to cause a significant increase in flow over the auto-regulatory range of 70-130 mm Hg. We also showed that inflammation decreases CF.