1. Department of Pediatrics and Child Health, Red Cross War Memorial Children's Hospital, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
2. Division of Pediatric Cardiology, Department of Pediatrics and Child Health, Red Cross War Memorial Children's Hospital, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, South Africa
3. School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, South Africa
4. Burden of Disease Research Unit, South African Medical Research Council Francie Van Zijl Drive, Cape Town, South Africa
5. Division of Pediatric Cardiology, Department of Pediatrics and Child Health, University of Stellenbosch, Cape Town, South Africa
6. Chris Barnard Division of Cardiothoracic Surgery, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, South Africa
7. Division of Cardiology, Department of Medicine, Groote Schuur Hospital, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, South Africa
8. South African Medical Research Council Francie Van Zijl Drive, Cape Town, South Africa