Fontan Circulation

Fontan Circulation

Fontan repair of tricuspid atresia was initiated in late 1960s. Francis Fontan et al reported that surgical repair was carried out in three patients with tricuspid atresia of which two were successful [1]. Inferior venacaval blood was directed to the left lung and the right pulmonary artery received the superior venacaval blood through a cavopulmonary anastomosis. They mentioned that the size of the pulmonary arteries must be large enough and at sufficiently low pressure to allow flow in a cavopulmonary anastomosis.

The first step was a Glenn procedure in which distal end of right pulmonary artery was anastomosed to the superior vena cava. Proximal end of the right pulmonary artery was anastomosed to the right atrium so that after closure of the atrial septal defect, inferior vena caval blood is directed to the left pulmonary artery. The main pulmonary artery was ligated at its exit from the hypoplastic right ventricle. Two aortic or pulmonary valve homografts were used to propel inferior vena caval blood to left lung. One was at the junction of inferior vena cava and right atrium to prevent back flow of blood during atrial systole. The other was at the anastomosis of right atrial appendage to the proximal end of the right pulmonary artery, to prevent reflux from left pulmonary artery to right atrium during atrial diastole [1].

Various modifications for Fontan procedure have since been introduced. Total cavopulmonary connection (TCPC) by Marc de Leval et was published in 1988 [2]. The procedure consisted of three parts: end to side anastomosis of superior vena cava to the undivided right pulmonary artery; creation of a composite intra atrial tunnel using the posterior wall of the right atrium and a prosthetic patch to channel inferior vena cava blood to the enlarged orifice of the transected superior vena cava that is anastomosed to the main pulmonary artery. Other variations of the procedure have used intracardiac and extracardiac conduits. Indications were expanded to include right or left atrioventricular valve atresia, abnormalities of pulmonary venous connection and even hypoplastic left heart syndrome. Operative and short term mortality of these patients were more than most other surgeries for congenital heart disease and hence careful patient selection was needed while planning to create a Fontan circulation [3].

The concept of two stage repair – initial hemi-Fontan in which superior vena cava was anastomosed with branch pulmonary artery followed a few months later by completion Fontan connecting inferior vena cava to branch pulmonary arteries, was introduced by Norwood WI et al [4].

Long term follow up after Fontan operation has been published from Mayo Clinic [5]. They reviewed the outcome of all patients who had undergone modified Fontan operation between 1973 and 2012. 10 year survival for the 1052 patients in the database was 74%. 20 year survival was 61% and 30 year survival 43%. Factors associated with decreased survival were pre-operative diuretic use, longer cardiopulmonary bypass time, surgery prior to 1991, atrioventricular valve replacement at the time of Fontan procedure, elevated post-bypass Fontan (>20 mm Hg) or left atrial pressures (>13 mm Hg), prolonged chest tube drainage beyond 21 days, post operative arrhythmias, renal insufficiency and development of protein losing enteropathy. Sinus rhythm was associated with improved survival. Most common reoperations were pacemaker insertion/revision, Fontan revision/conversion and atrioventricular valve replacement. Clinically significant late arrhythmias occurred in 44%. Protein losing enteropathy developed in 9% of patients. Protein losing enteropathy markedly reduced survival. Ten year survival came down to 35% and 20 year survival to just 19%. 

Twenty year survival of 84% after modified Fontan procedure has been reported in another series of 305 patients operated between 1980 and 2000 [6]. They noted better survival with improved techniques. 15 year survival was 81% after atriopulmonary connection versus 94% for lateral tunnel.

Fontan circulation is basically a single ventricle heart with the dominant ventricle supporting the systemic circulation and passive flow into the pulmonary circulation through cavopulmonary connection. Heart failure was the mode of death in 34% in a series of 600 adult Fontan survivors. Arrhythmia or sudden death was the reason in 24% [7]. Atrioventricular valve regurgitation is often associated with ventricular failure and it can be progressive. Pleural effusion, chylothorax and plastic bronchitis are important pulmonary complications associated with Fontan circulation. Predisposition to thrombosis and thromboembolism are also well known. It contributed to 7.9% of the late deaths in one study [8].

References

1. Fontan F, Baudet E. Surgical repair of tricuspid atresia. Thorax. 1971 May;26(3):240-8. 
2. de Leval MR, Kilner P, Gewillig M, Bull C. Total cavopulmonary connection: a logical alternative to atriopulmonary connection for complex Fontan operations. Experimental studies and early clinical experience. J Thorac Cardiovasc Surg. 1988 Nov;96(5):682-95.
3. Kutty S, Jacobs ML, Thompson WR, Danford DA. Fontan Circulation of the Next Generation: Why It’s Necessary, What it Might Look Like. J Am Heart Assoc. 2020 Jan 7;9(1):e013691.
4. Norwood WI, Jacobs ML. Fontan’s procedure in two stages. Am J Surg. 1993 Nov;166(5):548-51. 
5. Pundi KN, Johnson JN, Dearani JA, Pundi KN, Li Z, Hinck CA, Dahl SH, Cannon BC, O’Leary PW, Driscoll DJ, Cetta F. 40-Year Follow-Up After the Fontan Operation: Long-Term Outcomes of 1,052 Patients. J Am Coll Cardiol. 2015 Oct 13;66(15):1700-10. 
6. d’Udekem Y, Iyengar AJ, Cochrane AD, Grigg LE, Ramsay JM, Wheaton GR, Penny DJ, Brizard CP. The Fontan procedure: contemporary techniques have improved long-term outcomes. Circulation. 2007 Sep 11;116(11 Suppl):I157-64. 
7. Ohuchi H, Inai K, Nakamura M, Park IS, Watanabe M, Hiroshi O, Kim KS, Sakazaki H, Waki K, Yamagishi H, Yamamura K, Kuraishi K, Miura M, Nakai M, Nishimura K, Niwa K; JSACHD Fontan Investigators. Mode of death and predictors of mortality in adult Fontan survivors: A Japanese multicenter observational study. Int J Cardiol. 2019 Feb 1;276:74-80. 
8. Khairy P, Fernandes SM, Mayer JE Jr, Triedman JK, Walsh EP, Lock JE, Landzberg MJ. Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery. Circulation. 2008 Jan 1;117(1):85-92.