PATHOPHYSIOLOGY AND NATURAL HISTORY CONGENITAL HEART DISEASE Flow dynamics in the main pulmonary artery after the Fontan procedure in patients with tricuspid atresia or single ventricle

We analyzed the flow velocity pattern in the main pulmonary artery after Fontan operation in patients with tricuspid atresia (n = 10) or with single ventricle (n = 10) by means of a catheter-mounted velocity probe. The area underneath the velocity signal of the forward flow was integrated, and ratios of the portions during atrial systole and during the diastolic phase to the total area (Fa and Fd) were calculated. The Fa was 0.54 + 0.09 in patients with tricuspid atresia and 0.45 + 0.05 in those with single ventricle (p < .01). Cardiac output, obtained by the thermodilution method, was 2.45 ± 0.48 liters/min/m2 in patients with tricuspid atresia and 2.75 ± 0.72 liters/min/m2 in those with single ventricle. The forward flow during atrial contraction, calculated by multiplying Fa by cardiac output, was 1.32 + 0.35 liters/min/m2 in patients with tricuspid atresia and 1.23 ± 0.33 liters/min/m2 in those with single ventricle. The diastolic forward flow, calculated from Fd and cardiac output, was 0.99 ± 0.25 liter/min/m2 in patients with tricuspid atresia and 1.52 ± 0.45 liters/min/m2 in those with single ventricle (p < 0.005). The sum of cross-sectional areas of the right and left pulmonary arteries normalized by body surface area (PA index) was 282 ± 85 cm2/m2 in patients with tricuspid atresia and 462 ± 65 cm2/m2 in those with single ventricle (p < .005). The Fa was inversely correlated with the PA index in the whole group (r = .69) and also in the tricuspid atresia group alone (r = .87). Postoperative right atrial and pulmonary arterial pressures were 16 ± 3 and 16 ± 4 mm Hg in patients with tricuspid atresia and 15 ± 3 and 13 ± 3 mm Hg in those with single ventricle. Right atrial maximum volume, determined angiographically, was 169 ± 87% of normal in patients with tricuspid atresia and 105 ± 32% of normal in those with single ventricle (p < .01), but the ejection fraction was similar in the two groups (0. 30 ± 0.08 vs 0.29 ± 0.06). The data indicate that the relative role of right atrial contraction may become more important in patients with a smaller PA index, right atrial output is constant regardless of the PA index or the type of anomalies, and the amount of diastolic forward flow is influenced by the PA index. Thus the preoperative PA index is an important determinant of postoperative hemodynamics. Circulation 75, No. 6, 1117-1123, 1987. SEVERAL INVESTIGATORS have demonstrated a flow velocity pattern in the right heart in resting patients who have undergone the Fontan operation. 3̀ In the main pulmonary artery, two peaks of forward flow were recorded; one was during right atrial contraction and the other during the diastolic phase. These findings were analyzed qualitatively, but it has yet to be clarified whether there are any factors that quantitatively determine the forward flow of the right heart. From the Departments of Pediatric Cardiology and Pediatric Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical College, Tokyo, Japan. Address for correspondence: Makoto Nakazawa, M.D., Department of Pediatric Cardiology, The Heart Institute of Japan, Tokyo Women's Medical College, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162, Japan. Received Sept. 22, 1986; revision accepted Jan. 22, 1987. Vol. 75, No. 6, June 1987 We have observed that patients with a large pulmonary artery do better after the Fontan procedure than those with a small pulmonary artery, when the other criteria for the procedure are similar. Likewise, patients with tricuspid atresia do better than those with single ventricle after the operation. One would expect that these differences influence the postoperative hemodynamics. Of the different variables, we focused our attention on blood flow in the pulmonary artery in the present study. For that purpose, we quantitatively analyzed the blood flow in the main pulmonary artery in resting patients with tricuspid atresia and single ventricle after the Fontan operation by means of a cathetermounted velocity probe. We related the blood flow especially to the type of cardiac anomaly and the sum 1117 by gest on Sptem er 1, 2017 http://ciajournals.org/ D ow nladed from