Tain-Yen Hsia1, Sachin Khambadkone2, Scott M. Bradley1, Marc de Leval2; 1Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC; 2Great Ormond Street Hospital for Children, NHS Trust, London, United Kingdom
Objective: We have shown failing Fontan patients have poor subdiaphragmatic venous hemodynamics. Phrenic nerve paralysis, which may occur prior to or during Fontan completion, increases incidences of ascites and pleural effusion. Diaphragm plication has been suggested to correct these morbidities. This study aims to find out if diaphragm plication can restore the fluid dynamics to that of well-functioning Fontan patients with normal respiratory mechanics.Methods: IVC, hepatic (HV), and portal (PV) venous flows were studied in 19 normal volunteers (Nml), 9 patients with biventricular circulation post diaphragm plication (Nml-DP), 17 with total cavopulmonary connection (TCPC), and 7 with TCPC post diaphragm plication (TCPC-DP). Volumetric flow rates were measured with Doppler under dynamic respiratory monitoring. Effect of respiration is expressed as the ratio of inspiratory/expiratory flow, evaluated in both supine (sup) and upright (up) positions. Effect of gravity is expressed as the ratio of Up/Sup flow.
Results: Shown in tables. * P = 0.05.
Conclusion: Even in biventricular circulation, diaphragm plication does not completely restore normal splanchnic venous fluid dynamics. In Fontan patients, IVC and HV flow are driven by respiration. Following diaphragm plication, portal venous flow loses the normal expiratory augmentation; and additionally, the inspiratory drive of HV flow is suppressed in both supine and upright positions. These observations are similar to previously reported flow dynamics in failing Fontan patients. This suboptimal splanchnic circulation may not only contribute to early problems of prolonged pleural effusion and ascites, but can potentially increase the risks for late Fontan failure. Phrenic nerve injury should consequently be avoided at all costs prior to or at the time of the Fontan operation.
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