We report a rare variation in the pattern of totally anomalous pulmonary venous connection in that two vertical veins drained into the left brachiocephalic vein from a common pulmonary venous confluence. The child had associated right isomerism and functionally univentricular heart. Awareness of this possibility may avoid a reoperation or even death.

The surgical strategy for patients having a functionally single ventricle associated with totally anomalous pulmonary venous connection and pulmonary atresia with non-confluent pulmonary artery has yet to be agreed. We created an intraatrial tunnel to produce a total cavo-pulmonary connection in such a patient, also creating a confluence for the pulmonary arteries. By minimizing the use of the GoreTex patch, the patient was able to discontinue the use of warfarin.

Although patients undergoing surgery with the Fontan procedure or its modifications are increasingly recognised to be at risk for thromboembolism, further knowledge is needed to minimise this complication and its sequels. To address this issue, we reviewed 100 patients operated with the Fontan procedure, the bidirectional Glenn anastomosis and/or the total cavopulmonary connection to describe our incidence and clinical characteristics of postoperative formation of thrombus. Symptomatic thrombosis or cerebrovascular accidents were found in 5 patients. Asymptomatic thrombus were found in another 5 patients. Three patients had venous thrombi. In 6 patients the thrombosis was found on the arterial side. In all these cases, the thrombus was located in the stump of the divided pulmonary trunk. In 3 of these patients, sudden onset of hemiparesis preceded the diagnosis of the thrombus while the remaining 3 patients were asymptomatic. In 3 cases, the formation of thrombus in the stump of the divided pulmonary trunk occurred after a bidirectional Glenn anastomosis. One patient developed severe neurological symptoms 2 months after a total cavopulmonary connection. No thrombus was found, but the patient had a small right-to-left shunt and embolization could not be excluded. The incidence of thrombosis after Fontan-type surgery in this study is 10%. Although not all episodes of thrombosis are symptomatic, there is a significant risk of severe sequels due to embolization to the pulmonary or cerebral circulations. The stump of the divided pulmonary trunk is one of the main sites for intracardiac formation of thrombus, even after a bidirectional Glenn anastomosis.

It has long been known that the most complex combinations of cardiac malformations are those found in the setting of the so-called “splenic syndromes”.1 Many aspects of these syndromes have been controversial over recent years, not least the presence or absence of features of isomerism within the heart.2,3 Recent experience with genetic manipulation of mice, nonetheless, has now shown that it is possible to generate unequivocal evidence of cardiac isomerism, particularly in those animals which show features of right isomerism when the genes responsible for morphologically leftness are knocked out.4 Furthermore, when the crucial philosophical principle known as the “morphological method”5 is applied to the hearts of patients known to have visceral heterotaxy, it is equally clear that patients falling within these groups, when judged on the extent of the pectinate muscles relative to the atrioventricular junctions, exhibit isomerism of either the morphologically right or left atrial appendages.3

Hearts which, at first sight, seem to have a solitary chamber within their ventricular mass have long been the subject of controversy. As difficult as it is to manage these cardiac malformations medically and surgically, it has been at least as challenging, to date, merely to describe and classify them. Even the most commonly used terms, “single ventricle” and “univentricular heart”, spark heated debate. In distant times, when congenitally malformed hearts were pathological curiosities, these entities were described as “cor triloculare biatriale”. Therein lies the beginning of the problem, since when hearts of this type were examined by more enlightened pathologists, such as the great Maude Abbott,1 it became plain that the apparently solitary ventricular mass in reality possessed a second, albeit much smaller, chamber. Abbott described this second structure as the “outlet chamber”. This convention of describing a “single ventricle”, albeit with a co-existing “outlet chamber”, that presumably lacked ventricular status, continued throughout the first half of the twentieth century, although it had been recognised by then that hearts could rarely be found with truly solitary ventricles, and these were typically deemed to be common structures. Van Praagh et al.2 neatly summarised the problem with this approach when they pointed out that the so-called “single ventricle” possessed two ventricular chambers, whilst the “common ventricle” described the truly solitary arrangement. In their seminal investigation of 1964, Van Praagh et al.2 analysed only those hearts unified because of double inlet atrioventricular connection, or alignment. They excluded arbitrarily from their investigation all hearts with atrioventricular valvar atresia, despite the similarity in morphology between many of these latter lesions and the hearts with double inlet.3

The recent significant reduction in operative mortality associated with surgical completion of the Fontan circulation is clearly multi-factorial. Better understanding of the fundamental physiological and anatomical issues have led to refinements in operative technique, early neutralization of potential risk factors, widespread use of a staged approach, and selective application of the concept of fenestration or incomplete partitioning. While further reduction of operative mortality is important, and may be anticipated in the future, major emphasis now must be placed on optimizing functional outcome, and understanding and managing the late complications associated with the unique physiology produced by the Fontan circulation.

The nomenclature and classification of patients with a functionally univentricular heart has been debated for decades. We review here the approach taken for dealing with this group of patients by the International Working Group for Mapping and Coding of Nomenclatures for Paediatric and Congenital Cardiac Disease. We discuss the approach of this Nomenclature Working Group in the context of other historical and contemporary ideas about this topic.

It was in 1971, Fontan and Baudet1 published their experience using a surgical procedure to restore a physiologic circulation in three patients with tricuspid atresia. Of the three patients, two survived, thus ushering a new era in the treatment of children with complex forms of congenital cardiac disease. This operation itself, however, was the culmination of a series of experimental and clinical observations that underlined the clinical possibility totally to bypass the right side of the heart.

Many patients with a functional univentricular heart were treated in the 1970s and 1980s, using an atriopulmonary connection to create the Fontan circulation.1–3 Although this procedure, in many patients, was initially successful, and provided arterial saturations of oxygen close to normal, as these patients were followed over the years, in some cases they developed significant complications. One complication of the atriopulmonary connection is progressive right atrial dilation, which leads to atrial arrhythmias, such as atrial flutter or fibrillation.4,5 The combination of these two problems leads to low cardiac output, diminished quality of life, and poor categorization within the classification of the New York Heart Association. This, and other issues, has led most centres to abandon the atriopulmonary connection as a means of creating the Fontan circulation in favour of the lateral tunnel with cavopulmonary connections,6 or the extracardiac conduit.7

Patients with a functionally univentricular circulation represent a challenge for both surgeons and cardiologists. In this introductory paper, we aim to describe the variability in cardiac phenotype amongst these patients, and to review how function might relate to anatomy.

Whatever the specific anatomy, the Fontan circulation, be it created directly or subsequent to a bi-directional cavopulmonary anastomosis, transforms completely the pattern of circulation of the blood. In essence, it converts a network of circulations in parallel into one in series. The haemodynamic consequences are numerous. The most important and direct among them is, perhaps, the increase in afterload, as well as the reduction in preload, for the systemic ventricle. From the clinical point of view, the most immediate and relevant implication is the amelioration of cyanosis, this being the consequence of removing the common mixing of systemic and pulmonary venous blood within the heart.