Discussion

In 1824, Andrew HolmesReference Holmes¹ described the index case of a double inlet left ventricle with concordant ventriculoarterial connections. The case achieved much notoriety when it was re-published some 80 years later by Maude AbbottReference Abbott² at the behest of William Osler. For many, it heralded the arrival of congenital cardiac disease as a speciality in its own right. In the original description, Holmes described the condition as an intermediate between a true single ventricle and the normal heart^. Nowhere is this description better realised than in the present case in which the second chamber is quite clearly a morphological right ventricle.

Our patient unequivocally has the anatomy of the “Holmes’ heart”; however, her heart is distinguished by the straddling right atrioventricular valve that is firmly attached to the crest of the malaligned ventricular septum. The ventricular septal defect, which had been present, is thus closed by a connecting tongue of valvar tissue, analogous to the situation seen in the “ostium primum” defect with a common atrioventricular junction. In addition, the straddling of the right atrioventricular valve results in a valve with two orifices. In this respect, the heart functionally represents a variant of a “double outlet right atrium”, though admittedly it is the ventricular septum rather than the atrial septum that is deviated. Achieving a diagnosis by echocardiography was possible only by using the sequential segmental approach to interpret these connections.Reference Anderson, Becker and Freedom³

In 1951, Lambert first described the straddling of the tricuspid valve in a patient with double inlet left ventricle, a large ventricular septal defect, and ventriculoarterial discordance.Reference Lambert⁴ Milo et alReference Milo, Ho and Macartney⁵ later published the largest series of these cases in which they described several sub-types and commented on the disposition of the conducting system. Only once has a straddling tricuspid valve been reported without a ventricular septal defect: in a 4-year-old with pulmonary atresia and intact ventricular septum.Reference Isomatsu, Kurosawa and Imai⁶ Prolongation of the PR interval in our case supports the supposition, as is usual in the double inlet left ventricle, that there is likely to be an anomalous atrioventricular node located anterolaterally around the right atrioventricular orifice.

Most variants of the double inlet left ventricle present prenatally or in early infancy. Prognosis is poor and not improved by neonatal surgery.Reference Tham, Wald and McElhinney⁷ The anatomical arrangement described here is of interest because of the patient’s relative lack of symptoms, two normal pregnancies, and late survival. In the absence of a ventricular septal defect, she was not exposed to the damaging effects of cyanosis or the consequences of elevated pulmonary pressures. Despite less than half of the right atrioventricular junction being connected to the hypoplastic right ventricle, it clearly receives almost all right atrial output. This is relevant to the debate regarding indications for one and a-half ventricular repair as it highlights the fact that size alone does not predict a ventricle’s ability to successfully support the pulmonary circulation.Reference Hanley⁸

In our patient, as is frequent in adults with congenital cardiac disease, clinical deterioration accompanied the onset of atrial arrhythmia almost certainly resulting from chronically elevated right atrial pressure. The presence of the pericardial effusion may be attributable to the haemodynamic situation; however, other aetiologies such as malignancy should also be considered. By virtue of selection, this patient’s greatest future risk remains acquired and not congenital cardiac disease. Occasionally, complex congenital cardiac disease presents at unexpected moments. Such cases can provide fascinating morphological insights and may cause us to re-evaluate conventional understanding of certain conditions and their treatment.