Ascending aortic dilatation (AoD) in patients with structurally normal hearts and congenital heart block (CHB) has been previously described. The cause and management of AoD are yet to be determined. The aim of this study was to test the hypothesis that AoD in children with CHB regresses after the implantation of cardiac dual-chamber pacemakers (PMs). The secondary hypothesis was an association between the presence of maternal antibodies (SS-A or SS-B) and the degree of aortic dilatation. Clinical data with echocardiographic correlates of patients with CHB followed at a single institution were retrospectively reviewed. Comparison of the target structures diameter was based on 3 different z-score equations, with AoD defined as a z score >2. Inclusion criteria were CHB diagnosis by 12-lead electrocardiography or Holter recording and benefit from a permanent dual-chamber PM. Excluded were patients with incomplete echocardiographic measurements, those with major structural heart defects, and those with syndromes or diseases known to be associated with AoD. There were 17 patients, diagnosed at a median age of 6 months (interquartile range 0 to 47.8). Maternal antibodies were positive in 6 patients and negative in 11. All patients underwent PM implantation at a median age of 4.5 years (interquartile range 1.4 to 7.9). AoD (z score >2.0 according to 3 different equations) was present in 35% to 59% of patients. There was a significant reduction of mean ascending aortic z score in patients with AoD from 4.66 to 3.67 (p = 0.06), from 4.82 to 2.95 (p = 0.002), and from 6.07 to 3.39 (p = 0.006) according to the various z-score equations. Most patients with positive serology had AoD, without reaching statistical significance. In conclusion, AoD is associated with CHB, more likely in infants exposed to maternal antibodies. AoD decreases after the implantation of a PM. This is probably related to the regularization of stroke volume.
Congenital heart block (CHB) in the absence of a structural cardiac anomaly affects 1 in 14,000 to 1 in 20,000 live births and can potentially be lethal for the fetus or newborn, warranting early recognition and intervention. Morbidity and mortality in CHB have been linked to heart failure, hydrops, low fetal and neonatal heart rate, and neonatal problems associated with prematurity or systemic lupus erythematosus. Late-onset cardiomyopathy, isolated endocardial fibroelastosis, and, recently, ascending aortic dilatation (AoD) have been associated with CHB. In a study by Jaeggi et al, 95% of cases had positive anti-Ro (SS-A) or anti-La (SS-B) maternal serology. In our experience, AoD is present in patients with CHB. Although this association has been described recently by other groups, the cause and management of AoD associated with CHB have yet to be determined. We hypothesized that AoD in patients with CHB could regress after the implantation of a permanent dual-chamber pacemaker (PM). Our primary objective was to calculate the extent of AoD in children with CHB and to validate whether AoD regresses after PM implantation. A secondary objective was to investigate the association between maternal antibodies and AoD in this population.
Methods
The institutional research ethics board approved this retrospective study. The clinical database of the Division of Pediatric Cardiology at our institution was reviewed to identify the target population. Three equations were used for z-score calculation of the ascending aorta to identify subtleties in the degree of aortic dilatation and as a matter of comparison with previously reported studies. The 3 sets of equations were those published by Sluysmans and Colan and used by Radbill et al in their first report of AoD in patients with CHB, referred to as equation A; by Gautier et al, which takes into account the effect of gender, referred to as equation B; and derived from our echocardiography laboratory at CHU Sainte-Justine, including >1,300 healthy subjects between birth and 18 years of age, referred to as equation C (unpublished). Equation C also takes into account the subject’s gender. Z-score calculation was normalized to body surface area (BSA) in all 3 equations. The Haycock formula was used for the calculation of BSA by equations A and C (BSA [m 2 ] = height [cm] 0.3964 × weight [kg] 0.5378 × 0.024265), which is reported to be the most accurate in children, whereas the Dubois formula was applied for equation B (BSA [m 2 ] = height [cm] 0.725 × weight [kg] 0.425 × 0.007184) to adhere to the method described in the source article. Left ventricular end-diastolic and end-systolic diameters were measured by M-mode echocardiography. The left ventricular ejection fraction (LVEF) and stroke volume were calculated using the end-diastolic and end-systolic volumes as calculated by the Teichholz formula. Stroke volume index (SVI) was calculated using BSA per the Haycock formula. Z scores for left ventricular end-diastolic diameter were calculated as previously described.
Included in this study were children with CHB or childhood heart block on the basis of 12-lead electrocardiography or Holter recordings who were followed at our institution from 1984 to 2012 and who required PM implantation. The exclusion criteria were the absence of available echocardiographic measurements of the aorta before and/or after implantation of the PM, structural heart defects, syndromes or diseases known to be associated with aortic dilatation, myocarditis, neuromuscular disorders, and postoperative or postcatheterization heart block.
AoD was defined as a z score >2.0 according to the aforementioned equations. Baseline values were those recorded shortly before PM implantation. Follow-up values represent the last available data. Data included demographic information (weight, height, and ages at various stages of the assessment), history of presentation, physical exam and clinical evolution, presence of maternal antibodies, Holter recordings, and echocardiographic parameters (sizes of the aortic valve annulus, the aortic root, and the ascending aorta; the ejection fraction; and the shortening fraction).
Data are expressed as mean ± SD or median (interquartile range [IQR]). Paired Student’s t tests were performed to compare patients’ z-score status before and after PM implantation in case of a normal distribution. Otherwise, Wilcoxon’s signed-rank test was applied. McNemar’s test was used to compare proportions of AoD before and after PM implantation. Subanalysis was performed to compare the progress of ascending aortic z scores in patients with and those without AoD. Fisher’s exact test was used to validate potential categorical associations. Statistical significance was determined as a p value <0.05. Analysis was performed using SigmaStat version 3.5 statistical software (wpcubed GmbH, Munich, Germany).
Results
Thirty-one patients with CHB were identified, of whom 17 (55%) met the inclusion criteria, and 14 were excluded because of missing measurable echocardiographic studies. The median age at diagnosis of CHB was 6.0 months (IQR 0.0 to 47.8). PM implantation was performed at a median of 4.5 years (IQR 1.4 to 7.9) years, and the last follow-up was performed at a median of 5.8 years (IQR 3.3 to 8.7) ( Table 1 ).
| Ab | Gender | Age Diagnosis (months) | Age Pre-Implant (months) | Age at Implant (months) | Age at Last f/u (months) | Pre-Implant Values | Post-Implant Values | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Z-scores | SVI | LVEF | Z-Score | Z-Scores | SVI | LVEF | Z-Score | |||||||||||
| Eq-A | Eq-B | Eq-C | LVEDD | Eq-A | Eq-B | Eq-C | LVEDD | |||||||||||
| 1 | − | M | 0 | 114 | 115 | 219 | 12,24 | 6,70 | 11,25 | 59,81 | 69,96 | 1,74 | 8,43 | 4,15 | 5,70 | 46,31 | 59,58 | 1,63 |
| 2 | − | M | 1 | 88 | 88 | 201 | 2,82 | 1,70 | 1,83 | 76,76 | 69,62 | 2,92 | 1,82 | 0,63 | 0,34 | 61,99 | 67,82 | 3,00 |
| 3 | − | F | 3 | 17 | 18 | 212 | 3,70 | 3,32 | 4,36 | 69,87 | 77,88 | 1,89 | 2,77 | 1,47 | 1,07 | 49,85 | 64,45 | 2,38 |
| 4 | − | F | 6 | 35 | 38 | 98 | 1,33 | 0,75 | 0,76 | 95,79 | 81,42 | 3,25 | 2,07 | 1,13 | 1,16 | 70,16 | 69,50 | 2,38 |
| 5 | − | F | 9 | 19 | 21 | 91 | 0,73 | 0,17 | 0,18 | 92,27 | 72,85 | 6,50 | 0,89 | 0,21 | 0,02 | 53,33 | 66,98 | 1,29 |
| 6 | − | F | 12 | 54 | 54 | 153 | 1,11 | 0,36 | 0,42 | 106,12 | 84,42 | 3.17 | 0,15 | −0,57 | −0,92 | 55,60 | 65,96 | 1,97 |
| 7 | − | M | 44 | 187 | 187 | 188 | 2,39 | 1,07 | 0,77 | 32,83 | 58,24 | −0,04 | 0,19 | −0,14 | −0,87 | 49,30 | 73,36 | 1,15 |
| 8 | − | F | 48 | 92 | 92 | 104 | 1,61 | 0,79 | 0,58 | 45,34 | 70,60 | 0,44 | 0,53 | −0,17 | −0,54 | 50,59 | 69,93 | 1,01 |
| 9 | − | F | 58 | 75 | 89 | 105 | 2,60 | 1,82 | 2,32 | 61,74 | 68,33 | 1,29 | 2,50 | 1,57 | 1,96 | 68,39 | 58,88 | 3,00 |
| 10 | − | M | 77 | 92 | 94 | 218 | 1,32 | 0,45 | 0,03 | 52,74 | 77,61 | 0,62 | 2,01 | 0,74 | 0,48 | 36,90 | 65,88 | 0,23 |
| 11 | − | M | 186 | 186 | 187 | 227 | −0,27 | −0,41 | −1,08 | 93,81 | 82,90 | 3,60 | −1,01 | −0,68 | −1,31 | 49,04 | 64,88 | 3,70 |
| 12 | + | F | 0 | 0 | 15 | 18 | −0,53 | −2,28 | −1,86 | 29,80 | 61,72 | −0,32 | 4,80 | 4,60 | 6,56 | 68,97 | 61,90 | 3,40 |
| 13 | + | M | 0 | 0 | 0 | 129 | 5,68 | 6,67 | 8,44 | 73,73 | 68,66 | 3,67 | 6,11 | 3,82 | 5,24 | 22,04 | 47,29 | 1,58 |
| 14 | + | M | 0 | 0 | 0 | 105 | 2,97 | 3,58 | 4,19 | 42,68 | 64,57 | 1,47 | 4,63 | 2,76 | 3,32 | 62,84 | 71,28 | 1,65 |
| 15 | + | M | 0 | 11 | 13 | 83 | 2,08 | 1,85 | 1,92 | 58,73 | 76,16 | 2,56 | 1,09 | 0,26 | −0,09 | 49,75 | 73,18 | 0,00 |
| 16 | + | M | 0 | 43 | 45 | 135 | 6,51 | 4,70 | 6,35 | 64,95 | 66,66 | 2,50 | 4,83 | 2,86 | 3,28 | 57,57 | 71,42 | 1,59 |
| 17 | + | F | 91 | 97 | 99 | 156 | 5,62 | 3,98 | 5,61 | 65,36 | 69,82 | 1,94 | 4,34 | 2,62 | 3,14 | 45,80 | 58,34 | 1,16 |
| Mean | 31 | 65 | 68 | 144 | 3,05 | 2,07 | 2,71 | 66,02 | 71,85 | 2,13 | 2,71 | 1,48 | 1,68 | 52,85 | 65,33 | 1,83 | ||
| SD | 50 | 60 | 59 | 60 | 3,09 | 2,45 | 3,54 | 22,11 | 7,35 | 1,69 | 2,48 | 1,69 | 2,46 | 12,15 | 6,66 | 1,04 | ||
| Median | 6 | 54 | 54 | 135 | 2,39 | 1,70 | 1,83 | 64,95 | 69,96 | 1,92 | 2,07 | 1,13 | 1,07 | 50,59 | 65,96 | 1,63 | ||
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