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  1. Marc Gewillig
  1. Correspondence to:
    Professor Marc Gewillig
    Pediatric Cardiology, Gasthuisberg University Hospital, B - 3000 Leuven, Belgium;

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A normal mammal cardiovascular system consists postnatally of a double—pulmonary and systemic—circuit, connected in series, powered by a double pump—the “right” and “left” heart.

Many complex cardiac malformations are characterised by the existence of only one functional ventricle. This “single” ventricle then has to maintain both the systemic and the pulmonary blood circulation, which are not connected in series but in parallel (fig 1A, B). Such a circuit has two major disadvantages: arterial desaturation, both at rest and increasing during exercise, and a chronic volume overload to the single ventricle. Chronic volume overload will in time impair ventricular function, causing from the third decade on a gradual attrition due to congestive heart failure, with few survivors beyond the fourth decade.

Figure 1

 (A) The normal cardiovascular circulation. The pulmonary circulation (P) is connected in series with the systemic circulation (S). The right ventricle maintains the right atrial pressure lower than the left atrial pressure, and provides enough energy to the blood to pass the pulmonary resistance. (B) The patient with a univentricular heart. The systemic and pulmonary circuits are connected in parallel, with a considerable volume overload to the single ventricle (V). The width of the line reflects the degree of volume load. There is complete admixture of systemic and pulmonary venous blood, causing arterial oxygen desaturation. (C) The Fontan circulation. The systemic and pulmonary circulations are connected in series. The right atrium (RA) or systemic veins are connected to the pulmonary artery (PA). The volume overload to the single ventricle is now less than expected for body surface area. In the absence of fenestration, there is no more admixture of systemic and pulmonary venous blood, but the systemic venous pressure is notably elevated. Ao; aorta; LA, left atrium; LV, left ventricle, RV, right ventricle.

In 1971 Francis Fontan1 from Bordeaux, …

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