Coronary blood flow assessed by transthoracic echocardiography in neonates

Coronary flow measurement has provided useful clinical and physiologic information. However, there is little information about values for coronary flow in normal neonates, much less neonates with congenital heart disease. The aim of this study was to assess coronary blood flow in normal neonates and to compare the results with those in infants with ventricular septal defect. The study groups consisted of 12 normal neonates and 9 infants with simple ventricular septal defect associated with pulmonary hypertension. Left ventricular dimension, left ventricular mass, and the diameter of the coronary vessel were measured by standard M-mode and two-dimensional echocardiography. Peak flow velocities, flow velocity integrals, and flow volumes in the left anterior descending and circumflex coronary arteries were measured. The flow signals from the left anterior descending and circumflex coronary arteries were recorded in 84% (10/12) and 17% (2/12), respectively, in the normal neonates and 78% (7/9) and 11% (1/9), respectively, in the patients. The left ventricular end diastolic diameter and mass were significantly lower in normal infants than in the infants with ventricular septal defect (1.56 +/- 0.11 vs 1.84 +/- 0.09 cm and 5.4 +/- 1.6 vs 8.8 +/- 0.8 g, respectively, p < 0.01). The mean peak diastolic velocity and the flow velocity time integral in the left anterior descending coronary artery were significantly lower in the normal neonates than in the patients (15 +/- 4 vs 28 +/- 6 cm/sec and 2.3 +/- 0.6 vs 5.9 +/- 1.5 cm, respectively, p < 0.01). The coronary flow volume was significantly lower in the normal neonates than in the patients (3.1 +/- 1.4 vs 7.9 +/- 4.7 ml/min, p < 0.05). However, the flow volume of the left anterior descending coronary artery/left ventricular mass did not show any significant difference between the two groups. Our study demonstrated in neonates that it is feasible to detect noninvasively and to evaluate the flow of the left anterior descending coronary artery under physiologic conditions and abnormal hemodynamic situations. Increased flow volume in the left anterior descending coronary artery in patients with ventricular septal defect may be a compensated mechanism for the increase in oxygen demand of hypertrophic myocardium of the left ventricle.