At age 31 the aorta-PA graft was coil embolized in preparation for the Fontan: the PDA was ligated, the VSD closed, the ASD closed, a 6 mm fenestration was created, the RA appendage was connected by graft to the left PA, an opening between the RA and the SVC was slightly enlarged to allow some atrial return to the right lung. Due to cyanosis the ASD was closed with a clamshell occluder 2 months later (see transesophageal echo above).
Atrial arrhythmias began at age 25 and were medically treated. Atrial fibrillation recurred 6 years after the Fontan. Sinus rhythm was restored with amiodarone, digoxin, warfarin. An epicardial VVIR pacemaker was placed. VO2 was 14.5 ml/kg/min at baseline.
Clinical Course:
In clinic he felt fatigued. He was admitted to Yale-New Haven Hospital with HR 121 irregularly irregular, BP 123/60, O2 saturation on room air 89%. He had clubbing but no cyanosis. His chest had multiple scars. S1 was normal, a holosystolic 2/6 murmur was heard at the apex, S2 was single. INR 1.99, Hct 41, TSH<0.04.
Studies
CXR
ECG
Transesophageal echocardiogram
Hospital Course/Outcome
He admitted stopping amiodarone and digoxin months previously. Atrial fibrillation was rate controlled with a beta blocker and warfarin while his thyroiditis, presumed due to amiodarone, dissipated. He will return for treatment to restore sinus rhythm, perhaps requiring amiodarone.
Keys to clinical management:
1. Supraventricular tachyarrhythmias (SVT) may be fatal after the Fontan operation due to a critical decrease in cardiac output. Profound symptomatic hemodynamic deterioration is likely. Other causes of hemodynamic compromise after the Fontan operation can precipitate SVT. The Fontan circuit must be evaluated expeditiously with attention to obstruction, thrombus, systemic AV valve regurgitation, systemic ventricular function. The prevalence of SVT increased with time: for SVT occurring more than 30 days after the Fontan, the prevalence is 6% at 1 year, 12% at 3 years, and 17% at 5 years.
2. Amiodarone-induced thyroid abnormalities are more prevalent in patients with congenital heart disease compared to patients with aquired heart disease. Thirty-six percent of patients in one series developed thyroid dysfunction, roughly half hyperthyroid and half hypothyroid after approximately 3 years of amiodarone. Risk factors predicting thyroid dysfunction were Fontan-type surgery, cyanosis, and female gender. The imperative to restore sinus rhythm frequently necessitates amiodarone, increasing the complexity of thyroid management.
3. TEE may be the procedure of choice in assessing the Fontan circuit for thrombus and obstruction. TEE allows better 2-D and color Doppler evaluation of the LA, LAA, left AV valve, RA, RAA, the Fontan connection, shunts at the atrial level, the status of lateral tunnel or conduits, and possibly the SVC. TEE allows spectral Doppler evaluation of the Fontan circuit and pulmonary veins. TEE may obviate cardiac catheterization.
4. Systemic ventricular function may deteriorate as part of the natural history of single ventricle lesions including tricuspid atresia. The DDx of a decrease in systemic ventricular function s/p Fontan operation includes poor myocardial preservation intra-operatively, the effects of systemic AV valve regurgitation, myocardial venous congestion if the coronary sinus drains into the high pressure RA (controversial).
5. Exercise capacity after the Fontan operation is not normal. Exercise hemodynamic variables are typically 70% of age-predicted in stable Fontan patients. Maximum oxygen consumption (O2 ml/kg/min) is approximately 55% of predicted.
6. Oxygen saturation is less than normal after the Fontan operation in stable patients. This may be due to inter-cardiac communication such as a fenestration or a residual ASD, abnormal ventilation perfusion perhaps due to pulmonary AVMs, coronary sinus return to the left atrium. The incidence of pulmonary AVMs detected by pulmonary angiography is 20-25% after cavo-pulmonary anastomosis. Newer techniques such as bubble contrast echocardiography suggest the prevalence may be as high as 71%. Lung fields receiving no hepatic venous blood were more likely to develop pulmonary AVMs.
