MCQ 22: Fontan procedure 3 (32)

Q. True regarding Fontan surgery?

A. Bidirectional glenn shunt is usually done within 1 week of birth

B. PA banding may be required in patients with significant pulmonary stenosis prior to glenn surgery

C. Fenestration decreases post-op pleural effusion

D. Peri-operative mortality is around 20%

Answer: C. Fenestration decreased post-op pleural effusion

Explanation:

Fontan surgery is type of single ventricular repair required for some complex congenital heart diseases. It is a multistaged procedure.

Also known as Total cavopulmonary connection (TCPC).

It separates systemic and pulmonary circulation.

1^st stage procedure is done to normalize pulmonary blood flow (BT shunt in case of decreased pulmonary blood flow situations like PS and PA band in case of increased pulmonary blood flow situations). 2^nd stage is called bidirectional glenn shunt (BDG) or Hemifontan which is done at the age of 4-6 months and final stage is completion of Fontan

Advantages:

Near normalization of systemic saturation

Abolishment of chronic volume overload on single ventricle

Disadvantages:

Chronic systemic venous hypertension and congestion

Cardiac output is no longer determined by heart, but by transpulmonary flow (in turn regulated by PVR)-> leads to decreased cardiac output both at rest and during exercise

Indications:

—  Cardiac malformation and a single functional ventricle resulting from

◦      dysfunctional heart valve

◦      absent or inadequate pumping chamber

—  Most common CHDs palliated with fontan circulation :

◦      Tricuspid atresia

◦      Pulmonary atresia with intact ventricular septum

◦      Hypoplastic left heart syndrome

◦      Double-inlet ventricle

Perioperative mortality now is less than 5% and survival at 10 years has been shown to be around 80-85%.

Original Ten commandments by Fontan (Ideal candidate for surgery)

1. Age > 4 and < 15 years
2. Normal sinus rhythm
3. Normal systemic venous connections
4. Normal right atrial volume
5. Mean PA pressure ≤ 15 mmHg
6. Pulmonary vascular resistance < 4 Woods units/m²
7. Adequate-sized PA (PA to aortic diameter ratio ≥ 0.75)
8. Left ventricular ejection fraction ≥ 60%
9. Competent mitral valve (absence of mitral valve insufficiency)
10. Absence of PA distortion

Fontan Fenestration:

Small opening or fenestration may be created between the conduit and the right atrium at the time of surgery.

It improves cardiac output and decreased venous congestion. Fenestration decreased post operative pleural effusion. But, it comes at the cost of arterial desaturation.

Complications of Fontan: