Ascending aortic dilation in patients with congenital complete heart block

The clinical spectrum and underlying pathophysiology of isolated congenital complete heart block (CCHB) remain incompletely understood. Aortic dilation has been anecdotally observed in some children with CCHB, but detailed reports are lacking.

This study sought to systematically describe aortic size in children with CCHB and to investigate predictor variables associated with aortic dilation.

A retrospective review of clinical features and echocardiograms was performed for all patients with CCHB and a structurally normal heart or simple anatomic lesions seen at our center over 22 years. Echocardiographic measurements were assigned z-scores using validated norms.

Sixty subjects met inclusion criteria. The median ascending aorta (AsAo) z-score was 2.2 (range -0.6 to 7.2) at first echocardiogram, with 30 of 58 (52%) having a z-score >2 (P <.0001) and 11 of 58 (19%) having a z-score >4. The distribution of aortic root dimensions was nearly normal with a median z-score of 0.4 (range -1.3 to 3.2). Although the AsAo remained dilated at the last echocardiogram (median z = 1.7, range -0.9 to 6.3), the trend toward normalization was significant (P = .002). Maternal autoantibody seropositivity and decreased left ventricular function were associated with AsAo dilation at initial echocardiogram in a multiple logistic regression model controlling for heart rate and indexed stroke volume (odds ratio 15, P = .03, and odds ratio 0.8, P = .02, respectively).

Potentially clinically significant AsAo dilation, but not aortic root dilation, is present in a large proportion of pediatric patients with isolated CCHB. Maternal autoantibody seropositivity and decreased left ventricular function at initial echocardiogram correlate with this previously unreported finding. This observation may indicate a previously unrecognized consequence of fetal exposure to these autoantibodies.