THERAPY AND PREVENTION SURGERY Dynamics of right heart flow in patients after Fontan procedure

In seven patients who underwent Fontan procedures but in whom no valves were inserted, dynamics of right heart flow were evaluated with the use of a catheter-tipped velocity transducer, pulsed Doppler echocardiography, and angiocardiography. Right atrial (RA) contraction caused a forward flow to the pulmonary artery (PA) and a backward flow to the inferior vena cava (IVC). Backward flow to the superior vena cava (SVC) was minimal. As the right atrium relaxed, a rapid forward flow occurred at the IVC and SVC that filled the atrium and a small amount of pulmonary regurgitant flow was observed. Subsequently, a forward flow was observed at the IVC, SVC, and PA during RA diastole. Angiographically determined RA stroke volume (SV) was less than 40% of the left ventricular (LV) SV in three patients in whom the postoperative increase in atrial "a" wave pressure (Ap) was greater than 8 mm Hg, while it was similar to or greater than LVSV in four patients in whom Ap was 6 mm Hg or less. In all patients LV end-diastolic volume was 107 27(SD)% of normal but LV ejection fraction was 0.53 + 0.07, resulting in the reduced cardiac output (2.8 + 0.7 1/min/m2). There was no correlation between the RASV or RA ejection fraction and cardiac output. These data show that the RA contraction causes a forward flow to the PA and that pulmonary regurgitation is not significant after Fontan procedure even when valves are not inserted. Also, the postoperative increase in the RA afterload may depress RA function. The contribution of atrial contraction to output of the right heart may not be a major determinant of cardiac output. Circulation 69, No. 2, 306-312, 1984. SINCE Fontan et al. ' and Kreutzer et al.2 reported the surgical procedure of physiologic correction of tricuspid atresia, this type of operation has been successfully applied to various congenital heart diseases.'-' Postoperative hemodynamic studies6'2 have revealed that right atrial (RA) pressure is increased, especially in the "a" wave, which is transmitted to the pulmonary artery (PA), and that the pulmonary valve is found to open at the time of atrial contraction. Although these observations imply that RA contraction may play an important role in postoperative hemodynamics in these patients, dynamics of right heart flow have not been studied in depth. This study was undertaken to determine dynamics of right heart flow as well as RA and left ventricular (LV) volume characteristics in patients who have undergone Fontan procedure. Data were obtained with a catheter-tipped velocity transducer and From the Department of Pediatric Cardiology and Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical College, Tokyo. Address for correspondence: Makoto Nakazawa, M.D., Department of Pediatric Cardiology, The Heart Institute of Japan, Tokyo Women's Medical College, 10 Kawada-cho, Shinjuku-ku, Tokyo 162, Japan. Received July 5, 1983; revision accepted Oct. 6, 1983. by pulsed Doppler echocardiography and angiocardiography. Subjects and methods Seven patients who had undergone a modified Fontan procedure were studied during a period of from 4 weeks to 4 years after the operation. Their ages at the time of surgery ranged from 2 to 19 years. The diagnoses and surgical procedures for each patient are summarized in table 1. Valves were not inserted in any of the patients. The preoperative hemodynamic data are also presented in table 2. Right and left heart catheterizations were performed after patients were premedicated with 2 mg/kg meperidine and 1 mg/ kg hydroxyzine pamoate. Cineangiograms were recorded after injection of contrast medium into the inferior vena cava (IVC) and the main PA. The cine records served to determine the RA and LV volumes .Both volumes were calculated by the methods reported by Graham et al.'13 14 RA and LV ejection fractions (EFs) were obtained with the equation: (maximum volume minimum volume) . maximum volume. The maximum RA and LV end-diastolic volumes (EDVs) observed were compared with the expected normal values (RA volume = 54.6 x body surface area [BSA]I23,'3 LVEDV = 72.5 x BSA'43 15) and were expressed as a percentage of normal. Cardiac output was determined by the thermodilution method. In six of the seven patients, a catheter-tipped velocity transducer (Miller, Model VPC-663A) was introduced into the right side of the heart. Blood flow velocity was measured with an CIRCULATION 306 by gest on A ril 6, 2017 http://ciajournals.org/ D ow nladed from THERAPY AND PREVENTION-sURGERY TABLE 1 Patient characteristics Patient Previous Age at Interval after No. Diagnosis palliation Surgical procedure the surgery the surgery 1 TA lb BT at 2 yr RA-PA anastomosis 8 yr I mo 2 TA lIb BT at 1 yr RA-PA anastomosis 6 yr 1 yr 3 TA lb BT at 5 yr RA-PA anastomosis 10 yr I mo 4 TAl Ta r RA-RVO anastomosis 19 yr 4 yr TA lb BT at 8 yr VSD closure RA-PA anastomosis9yr1m 5 HPRV, DORV, PS none 9 yr i mo T valve closure 6 TA Ila none RA-PA anastomosis 9 yr 1 mo 7 TA Ib Potts at 1 yr RA-PA anastomosis 2 yr I mo TA = tricuspid atresia (classification: Edwards and Burchell; Keith); HPRV = hypoplastic right ventricle; DORV = double outlet RV; PS = pulmonary stenosis; BT = Blalock-Taussig shunt; RVO = RV outflow tract; T valve = tricuspid valve. electromagnetic flowmeter (Narco, Model RT-500) with a 30 Hz filter before angiographic examination. In all patients, pulsed Doppler echocardiography was performed to determine blood flow patterns at the IVC, hepatic vein, superior vena cava (SVC), and right and left PAs. The system used was a Toshiba SSH-l1A combined with an SDSlOA. The high-pass filter of the pulsed Doppler instrument was set at 200 or 400 Hz. The measurements were made at the end of expiration while patients were in the supine position. The transducer was placed in the subxyphoid region to obtain the flow pattern at the IVC and hepatic vein, the SVC flow pattern was recorded from the suprasternal approach, and the pulmonary flow pattern was obtained from the third left intercostal space. The effect of deep inspiration was studied in five patients by recording the flow pattern at the point of maximum inspiration.