Invited Commentary

Abstract

The unique pulmonary vascular resistance (PVR) characteristics of children born with Down syndrome (DS) have been well documented. The combination of functional upper airway obstruction and chronic hypoventilation creates a predisposition to increased PVR in DS patients. When single ventricle palliation (SVP) offers the only chance for long-term survival in DS, the treatment team faces a great challenge. Historically, SVP in DS has been considered high risk, with very few patients offered staged palliation and even fewer patients achieving modified Fontan status. It has been known since 1997 that early and aggressive control of pulmonary blood flow in DS patients allows them to achieve Fontan completion [1Spicer R. Uzark K. Cocalis M. Moore J. Mainwaring R. Lamberti J. Down syndrome and functional single ventricle: the Fontan approach.in: Imai Y. Momma K. Proceedings of the Second World Congress of Pediatric Cardiology and Cardiac Surgery. Futura, Armonk NY1997: 818-820Google Scholar]. In our series, both patients who achieved Fontan completion enjoy greater than 15-year survival [1Spicer R. Uzark K. Cocalis M. Moore J. Mainwaring R. Lamberti J. Down syndrome and functional single ventricle: the Fontan approach.in: Imai Y. Momma K. Proceedings of the Second World Congress of Pediatric Cardiology and Cardiac Surgery. Futura, Armonk NY1997: 818-820Google Scholar]. Colquitt and colleagues [2Colquitt J.L. Morris S.A. Denfield S.W. Fraser C.D. Wang Y. Kyle W.B. Survival in children with Down syndrome undergoing single-ventricle palliation.Ann Thorac Surg. 2016; 101: 1834-1841Abstract Full Text Full Text PDF Scopus (18) Google Scholar] reviewed a cohort of DS patients treated by SVP between 1992 and 2014 (28 patients). They compare this group of DS patients with a group of non-DS patients born with unbalanced atrioventricular septal defect (AVSD) unsuitable for septation (30 patients). The predominant lesion type in the DS group was unbalanced AVSD. The striking differences between the 2 groups were older age at superior cavopulmonary connection (SCPC), higher pre-SCPC PVR and higher pre-SCPC mean pulmonary artery pressure in the DS group. The majority of the DS group was palliated by pulmonary artery banding (79%). The overall 1- and 5-year survival in the DS group was 75% and 61% with the non-DS group achieving 93% and 85% survival, respectively. Univariate analyses show that PVR greater than or equal to 3 WUm2 in the first year of life was a significant predictor of mortality (hazard ratio, 10.6). Interestingly, PVR data was unavailable in 53% of patients without DS and 43% of patients with DS. Kaplan-Meyer survival analyses show better survival in the non-DS group. Of note, patients with DS and PVR less than 3 WUm2 had 100% survival. Early control of pulmonary blood flow in the subgroup of patients (DS) who are at higher risk for the development of elevated PVR may be the most modifiable factor in achieving successful palliation. At our institution, we have established an aggressive treatment plan for unbalanced AVSD in DS that enables SVP while permitting later conversion to 1.5 or biventricular repair, if feasible. Aggressive pursuit may require early pulmonary artery banding using the technique of an adjustable band [3El-Said H. Hamzeh R. Lamberti J. Moore J. Catheter balloon adjustment of the pulmonary artery band: feasibility and safety.Pediatr Cardiol. 2011; 32: 8-16Crossref PubMed Scopus (6) Google Scholar]. The authors correctly state that their study has many limitations. Medical management in patients with SVP has evolved considerably during the last 25 years, therefore the “era effect” may play a role in the improved outcomes noted in this report. Whatever deficiencies exist in this retrospective study, the outcomes demonstrated clearly illustrate that SVP can be achieved in many DS patients. The report provides a framework for creating a treatment plan for many DS patients requiring SVP. Finally, not all SV patients, whether DS or non-DS, will be candidates for SVP. Our role as surgeons and cardiologists will be to identify the patients that will most benefit from palliation to the modified Fontan procedure, while recognizing that some patients may be well served by other forms of palliation. Survival in Children With Down Syndrome Undergoing Single-Ventricle PalliationThe Annals of Thoracic SurgeryVol. 101Issue 5PreviewWe describe survival in patients with Down syndrome (DS) with single-ventricle anatomy and palliation and characterize risk factors associated with mortality. Full-Text PDF