Paralysis of the phrenic nerve as a risk factor for suboptimal Fontan hemodynamics

The introduction of the Fontan operation for single ventricle physiology was based on the dual principle of the pulmonary blood flow. It is postulated that normal breathing movements are necessary for passive blood flow into the lungs. We compared patients with and without palsy of the phrenic nerve regarding the sufficiency of Fontan hemodynamics.

We analyzed 85 consecutive patients, who were available for follow-up after completion of their total cavopulmonary connection (TCPC) between February 1992 and February 2003. The median age at TCPC completion was 4.3 (range 1.3-37) years. Sixty were operated on with an extracardiac conduit and 25 with a lateral tunnel. Fifty patients underwent postoperative heart catheterization with contrast angiography. The diagnosis of diaphragm paralysis was made using echocardiography, fluoroscopy and X-ray examination. Surgical diaphragm plication was performed in 13 patients (Four before and nine after Fontan operation) at a median of 2.2 years after the diagnosis.

Twenty-one patients developed fixed palsy of the phrenic nerve during a total of 225 operations before and including completion of TCPC. There were no differences in the incidence of phrenic nerve paralysis between small children (aged <3 years) and older patients or between patients with the extracardiac and intracardiac Fontan procedures. There were no differences in the duration of mechanical ventilation. However, prolonged pleural effusions and a hospital stay of longer than 2 weeks were noted more frequently in patients with palsy (P<0.05). During the median follow-up of 4.6 (range: 0.7-11.4) years significantly more patients with phrenic nerve palsy developed chronic ascites compared to those without palsy (8 of 20 vs. 2 of 65; P<0.001).

Phrenic nerve palsy was recognized as a risk factor for suboptimal Fontan hemodynamics due to the hindrance of passive venous blood flow. Patients with phrenic nerve palsy have a longer hospital stay and a higher incidence of prolonged pleural effusions and of chronic ascites, than those without. Early diaphragm plication may be favorable to optimize the Fontan circuit in these patients. Completion of the TCPC in patients with diaphragm paralysis should be viewed critically.