Andersons pediatric cardiology 1864

measured, and if the transpulmonary gradient is greater than 10 mm Hg and no obstruction in the Fontan pathway is identified, inhaled nitric oxide should be considered If a fenestration was not part of the original procedure, strong consideration should be given to adding one Desaturation with a normal or low central venous pressure suggests a right-to-left shunt This might be intrapulmonary due to preexisting pulmonary malformations (AVMs) or, in the case of a lateral tunnel Fontan, the right-to-left shunting could be intracardiac due to a baffle leak Although pulmonary AVMs will likely improve following a completion Fontan, a significant baffle leak will require immediate repair Again, careful evaluation with transesophageal echo can identify both baffle obstruction and baffle leaks and is an essential part of completion of the surgery Meticulous hemostasis is important as ongoing transfusion will negatively impact hemodynamics and lung function It is prudent to place chest tubes in both pleural spaces as pleural effusions are the rule following the Fontan Placement of temporary pacing wires is essential, even if the initial rhythm is satisfactory Arrhythmias are common postoperatively Temporary sinus node dysfunction is common following a lateral tunnel Fontan and is reported with extracardiac Fontan as well Postoperative Considerations Following the Fontan Procedure In the current era, mortality following the Fontan procedure approaches 1% In the most recent Society of Thoracic Surgeons–Congenital Heart Disease database report, the median hospital stay following the Fontan was 14 days.228 In a large recent single-center experience, Ono and colleagues reported a median duration of mechanical ventilation of 9 hours, and chest tube duration was 4 days.286 Factors associated with longer length of stay in the CICU included a diagnosis of hypoplastic left heart syndrome, anomalies of systemic venous drainage, elevated preoperative transpulmonary gradient, and decreased preoperative arterial saturation In the Single Ventricle Reconstruction Trial, which included patients with dominant right ventricles, the mortality was less than 1%.287 The median hospital length of stay was 11 days for the right ventricle-to-pulmonary artery conduit and 10 days for the Blalock-Taussig shunt Risk factors for longer hospital length include longer hospital length of stay after SCPC and pre-Fontan complications Postoperative considerations following the Fontan procedure are summarized in Box 71.8 Box 71.8 Postoperative Considerations Following the Fontan ■ Bedside preparedness ■ Noninvasive and invasive monitoring ■ Bleeding ■ Effects of positive-pressure ventilation and early extubation ■ Low cardiac output ■ Rhythm disturbances ■ Effusions Bedside Preparedness and Monitoring The principles of bedside preparedness are similar to those outlined earlier and include communication with the operating room and anesthesia team regarding the intraoperative course, bleeding, vasoactive agents, and echocardiographic findings Specifically following the Fontan, there are physiologic benefits to early extubation, and these should be discussed between the team in the operating room and the team in the CICU to confirm plans, have the necessary equipment available, and provide closed-loop communication Effect of Positive-Pressure Ventilation on the Fontan Circulation The Fontan circulation can be considered a preload-deficient state resulting from multiple factors In contrast to the SCPC circulation, where the majority of systemic venous return drains “directly” into the systemic ventricle, the Fontan circulation depends primarily on the residual energy from the systemic blood flow to drive blood back from the systemic venous reservoirs to the central venous circulation and ultimately across the pulmonary circulation to a ventricle (see Fig 71.1) While on PPV, elevated ITP impedes systemic venous return, which is worsened during the inspiratory phase of the ventilator; multiple studies have shown retrograde flow in the inferior caval vein and hepatic veins during this phase It has been shown that PPV decreases pulmonary blood flow and cardiac output, and negative-pressure ventilation (spontaneous breathing or negative-pressure ventilators) significantly improve pulmonary blood flow and cardiac output.288–295 In two prospective studies using Doppler echocardiographic assessment of pulmonary blood flow in three patients (mean age, 9.6 years) with left atrial isomerism/interrupted inferior caval vein after SCPC and 16 patients (mean age, 9.9 years) after a Fontan procedure, an increase in pulmonary blood flow during spontaneous inspiration and a decrease in pulmonary blood flow during expiration or with a Valsalva maneuver was observed.288,292 In summary, achieving spontaneous breathing without positive pressure as rapidly as possible will increase cardiac output and reduce central venous pressure This is the guiding principle of optimizing the Fontan circulation (see Chapter 70) Evaluation and Management of Low Cardiac Output Early After Surgery The signs of low cardiac output following a Fontan procedure may be rapidly progressive or more insidious The usual clinical signs include tachycardia, poor distal perfusion, decreased urine output; if progressive, a lactic acidosis will develop There are multiple potential etiologies that can be divided into three categories, as shown in Table 71.10; in some patients there may be multiple causes Table 71.10 Diagnosis and Management of Low Cardiac Output Following the Fontan Procedure CVP: high Atrial pressure: high Cardiac tamponade Factors increasing atrial pressure with normal TPG ■ Increased end-diastolic pressure ■ Systemic atrioventricular valve stenosis and/or regurgitation ■ Systemic ventricular systolic dysfunction (contractility) ■ Systemic ventricular diastolic dysfunction (hypertrophy, ↓ preload) High mean airway pressure (on positive-pressure ventilation) CVP may be further increased by factors that elevate TPG (see below) CVP: high Atrial pressure: low Obstruction of anastomoses from inferior caval vein to pulmonary artery Hypoplastic pulmonary arteries