Fontan Failure - Professor Richard Kirk 2023

Heart Failure
Introduction	Assessment	Investigations	Management	Myocarditis \| Fontan Failure		AHA Guidelines

Fontan Failure

Fontan physiology is such that most circulations will eventually fail. There are 3 main modes of failure: ventricular, systemic venous and lymphatic although they are not mutually exclusive. Investigation is always necessary to determine if there is an anatomic substrate as the mechanism of failure.

Ventricular Failure

The systemic ventricle provides the output for both systemic and venous circulations and thus has a very abnormal workload. Ventricular failure (systolic ± diastolic) or significant AV valve regurgitation will reduce cardiac output and lead to a high left atrial pressure, raising the systemic venous pressure causing congestion and impaired lymphatic drainage. However the management is similar to that of heart failure in a biventricular circulation. This type of failure is amenable to mechanical support if necessary.

Systemic Venous Failure

Fontan physiology inevitable leads to abnormally high systemic venous pressures. This causes venous congestion in various organs including the liver and intestines. Peripheral edema and ascites are common. The high venous pressure may also lead to collateral channels developing, allowing de-oxygenated blood into the left side and causing desaturation. Pulmonary arterial-venous malformations are not uncommon (PAVMs) and lack of a "liver factor" has been postulated as a cause. The management is primarily that of decongestion combined with therapy to decrease pulmonary vascular resistance. When desaturation is severe then occlusion of the collaterals may be necessary. Fontan Associated Liver Disease (FALD) may occur with liver fibrosis and focal nodular hyperplasia leading to cirrhosis and hepatocellular carcinoma in some patients - surveillance is thus necessary and detailed investigation necessary if transplantation is considered.

Lymphatic Failure

From elegant work by Dori et al in Philadelphia the effect of raised systemic venous pressure on the lymphatic system draining is becoming clearer. Impaired lymph drainage from the thoracic duct into the venous system leads to the development of channels into the lungs, intestines or peritoneum. Loss of lymph causes protein and electrolytes disturbances. In the lungs casts are formed (plastic bronchitis) which may be life threatening, in the intestines protein losing enteropathy develops and in peritoneum, ascites. A major constituent of lymph is interstitial fluid. Raised lymphatic pressure thus reduces the return of interstitial fluid to the venous system further compounding the effects of low plasma proteins and exacerbating edema.

Medical management consists of addressing any anatomic issues and maximizing heart failure treatment.

Plastic bronchitis treatment options include inhaled or systemic steroids, aerosolized mucolytics, and aerosolized fibrinolytics such as tissue plasminogen activator
Protein losing enteropathy treatment options have include heparin, octreotide, prednisone and budesonide along with supportive treatment of plasma and immunoglobulin infusions - all with limited success

More recently transcatheter approaches have been developed with resolution of symptoms in suitable patients in the short to medium term.