# Echocardiography in the Diagnosis and Management of Tricuspid Atresia
## 5 Echo-Doppler Studies Following Palliative/Corrective Interventions
### Echocardiographic Evaluation Following Completion of Fontan  
Subsequent to completion of Fontan procedure, periodic clinical follow up along with echo-Doppler studies is generally recommended at 1, 6, and 12 months after the procedure and yearly thereafter [36; 37; 38]. The LV is usually normal in size with normal LV systolic function (Figure 38) because the pulmonary and systemic circulations are completely separated during the final phase of Fontan. However, some patients may have dilatation of the LV with or without diminished LV systolic function, secondary to prolonged exposure to volume overloading, significant mitral insufficiency, previously undetected myocardial damage due to multiple surgical procedures under cardio-pulmonary bypass, or a combination thereof. Post-Fontan echocardiographic anatomy is best displayed in apical four chamber views, as demonstrated in Figures 38-40. The remnants of the RA and the LA are seen (Figures 38-40). The remnants of atrial septum are not usually seen since the atrial septum is completely removed either during bidirectional Glenn or Fontan surgery. Unobstructed pathway allowing emptying of blood flow from the coronary sinus and thebeesian veins is usually seen in an apical four chamber view (Figure 40). The LA is usually normal in size (Figures 38-40) and empties into the LV; laminar flow across the mitral valve (Figure 41A) can be seen. Drainage of all four pulmonary veins into the LA may be demonstrated by color flow mapping in multiple echocardiographic views. The LV is either normal in size or slightly dilated. In type I patients with normally related great arteries, the LV outflow into the aorta is demonstrable on echo-Doppler with laminar, unobstructed flow with near normal (\(\sim\)1.0 m/s) Doppler flow velocity (Figures 41B and 42). The RV is small and hypoplastic (Figures 39 and 40). If the VSD has already spontaneously closed (Figure 40), the RV has no communication with any other structures since the connection with the PAs has been severed during bidirectional Glenn or Fontan procedures. If the VSD did not undergo spontaneous closure, the RV forms a cul-de-sac connection with the LV (Figures 39 and 43). In Type I patients with atresia of both tricuspid and pulmonary  
Figure 38: Selected video frames showing left ventricle (LV) in diastole (LVD) (**A**) and in systole (LVS) (**B**) demonstrating normal ejection fraction (EF) of 63.4%. C, conduit; LA, left atrium. values (Type Ia), the hypertrophied RV may protrude into the LV outflow region (Figure 44). However, there is usually no evidence for obstruction across this region (Figure 45). Figure 40: Selected video frames from apical four-chamber views demonstrating unobstructed pathway (UOP) (long arrow) between the right and left (LA) atria; the mitral valve is closed in (**A**) while it is open in (**B**). ATV, atretic tricuspid valve; C, conduit; HRV, hypoplastic right ventricle; LV, left ventricle. Figure 39: Selected video frame from an apical four-chamber view demonstrating the left ventricle (LV), hypoplastic right ventricle (HRV) with an atretic tricuspid valve (ATV) in a patient who had Fontan procedure. Cross-sectional view of the conduit (COND) is also shown. Note small ventricular septal defect (VSD) (long arrow). Figure 41: Selected video frames from an apical views demonstrating laminar flow from the left atrium (LA) to the left ventricle (LV) (**A**) and from the LV to aorta (Ao) (**B**). Note laminar flow in the LV outflow tract (LVOT) (**B**). Medial portion of the conduit (C) is seen in (**A**). Figure 42: Selected video frames from an apical view demonstrating laminar flow from the left ventricle into the aorta (Ao). Note laminar flow in the LV outflow tract (LVOT) and low Doppler flow velocity (\(\sim\)0.8 m/s). In Type II patients with transposition of the great arteries, the LV outflow into the aorta is via the VSD and RV. If the VSD is large, the LV outflow is unobstructed (Figures 12 and 15).