The first patient was a four years old girl with hypoplastic left heart syndrome. She previously had undergone neonatal Norwood-Sano palliation and bidirectional cavo-pulmonary connection at the age of three months. Due to progressive cyanosis the patient was scheduled for tricuspid valve repair and TCPC. Preoperatively the patient had a well-tolerated junctional rhythm with constant retroconduction with preserved heart rate excursions.
Weaning from bypass was uneventful and the patient was successfully extubated after 12 hours.
During the first postoperative week abdominal congestion, right pleural effusion (Fig 1A) and progressive desaturation were observed. Blood chemistry disclosed increased liver enzymes and low albumin. Transthoracic echocardiogram showed normal ventricular function and mild AV valve regurgitation. Color-Doppler interrogation of the Fontan conduit and sovrahepatic veins, disclosed phasic hepatopetal signal consistent with a reversal flow through the fenestration on time with atrial retroconduction (Fig 2). This observation was consistent with the evidence of giant ‘atrial’ wave one the jugular venous pressure tracing. Upon atrial pacing the reverse component of flow disappeared with a slight increase in aortic velocity time integral (VTI).
Clinically, these echocardiographic changes were accompanied by resolution of pleural effusion and progressive increase of oxygen saturation and albumin normalization during the following days (Fig 1B). Based on this findings she was scheduled for permanent atrial pacing owing to persisting junctional rhythm.
The second patient was a five years old child who had undergone neonatal systemic to pulmonary shunt and cavo-pulmonary connection at the age of 9 months, due to severe symptomatic Ebstein anomaly. TCPC was planned because of progressive desaturation and effort intolerance. Few hours after cardiopulmonary bypass weaning he developed hypotension and low cardiac output syndrome requiring inotropic and vasopressor support. ECG disclosed competitive retroconduted junctional rhythm. Function of systemic ventricle and atrioventricular valve were normal. Similarly to the first case there was phasic reversal flow through the fenestration that was no longer detected during atrial pacing . Theses flow pattern changes translated into VTI increase and resolution of lactacidemia, in the following 24 hours, consistently with stroke volume and peripheral perfusion improvement. Permanent pacemaker implantation was not needed as sinus rhythm recovered after 72 hours.