Surgical management of hearts with isomeric atrial appendages.

BACKGROUND AND AIM: On the basis of previously published accounts, coupled with our own experience, we have assessed the surgical approaches to patients with isomeric atrial appendages. METHODS: We reviewed pertinent published studies on surgical treatment of individuals with isomeric atrial appendages, with the pertinent surgical details provided by most of the manuscripts. RESULTS: Half of patients with right isomerism, and two-thirds of those with left isomerism have bilateral superior caval veins. Azygos extension of the inferior caval vein is reported in three-quarters of those with left isomerism. The coronary sinus is universally absent in right isomerism, along with totally anomalous pulmonary venous connection, and is absent in two-fifths of those with left isomerism. Univentricular atrioventricular connections are expected in up to three-quarters of those with right isomerism. Atrioventricular septal defect is reported in up to four-fifths, more frequently in right isomerism, with such patients typically having discordant ventriculoatrial connections or double outlet right ventricle. Reported mortalities extend to 85% for those with right, and 50% for those with left isomerism. In right isomerism, mortality is up to 54% for systemic-to-pulmonary arterial shunting, up to 75% for univentricular repair, and up to 95% for repair of totally anomalous pulmonary venous connection itself. No more than one-quarter had undergone Fontan completion, with reported mortalities of 21%. CONCLUSION: Early surgical results are satisfactory in patients with left isomerism, but disappointing for those with right. Recent advances in cardiac and liver transplantation may offer improved survival.

Invited commentary: left isomerism or "isolated atrial inversion"?

In the accompanying article, Chenu and colleagues describe "an uncommon course of the right superior vena cava in a patient with heterotaxy syndrome." In their discussion, they pose the question, "Is this an isolated atrial inversion, or a case of left isomerism?" They proceed to comment "this remains a debate among cardiac morphologists." I can agree with them on their first description, since although I have previously examined many hearts from patients with isomerism of the left atrial appendages, or "polysplenia syndrome," I had not noticed the unusual feature they have emphasized in their case report; although, as I will show, the evidence was there for me to observe their feature of emphasis. They deserve great credit, therefore, for bringing this feature to our attention. I also agree with their first statement, namely that their patient has the left isomeric variant of the so-called visceral heterotaxy, but I must question their suggestion that the patient may exhibit mirror-imaged arrangement of the atrial chambers or "atrial situs inversus." I would question even more strongly their comment that the distinction remains "a debate among cardiac morphologists." As I will further show, the distinction has major clinical implications, not only for pediatric cardiac surgeons but also for those involved with genetic counseling.

Anatomy of common atrioventricular junction with complex associated lesions.

The essence of the lesion increasingly described as atrioventricular septal defect is the presence of a common atrioventricular junction. In most instances, the common junction is itself shared in more or less equal fashion between the cardiac chambers, producing the so-called balanced arrangement, which can be considered the default option. Complexity can be produced at various levels within this standard lesion. The most complex malformations are seen in the setting of visceral heterotaxy. Greatest complexity is seen with right isomerism. This always includes totally anomalous pulmonary venous connection, even when the pulmonary veins return to the heart. Still further complexity is often added by the presence of pulmonary stenosis or atresia. Imbalance can involve either the atrial or ventricular chambers. Imbalance at atrial level produces one form of double outlet atrium, but typically with balanced ventricles. Ventricular imbalance represents spectrums extending either to double inlet left or right ventricle through a common atrioventricular valve. Complexity at the level of the ventriculoarterial junctions is seen in the form of abnormal ventriculoarterial connections, notably tetralogy of Fallot or double outlet right ventricle. In these settings, the superior bridging leaflet is free-floating. Hypoplasia of the left atrioventricular valve is part of right ventricular dominance and is often associated with the so-called parachute malformation. Dual orifice is also a problem. In both these lesions, the zone of apposition between the bridging leaflets is the effective inlet to the left ventricle.