Biventricular function and dyssynchrony at rest and during exercise in children during the early years after tetralogy of Fallot repair

• Main Author: Roche, Susan Lucy
• Published: University of Newcastle Upon Tyne 2011
• Subjects: 618.921
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556124

Each year in the United Kingdom, approximately 250 babies are born with tetralogy of Fallot (TO F); a serious form of cyanotic congenital heart disease that is usually fatal if left untreated. Fortunately, as the result of pioneering work in the 1940s and 50s, the vast majority of infants born with this condition today survive corrective surgery and reach adulthood with a near normal quality of life. However, surgical repair of TOF is not a cure. A patient's residual anatomical, physiological and electrical abnormalities progress with time, causing vulnerability to late complications such as exercise intolerance, arrhythmia, heart failure and sudden cardiac death. The importance of a slowly evolving postoperative pathophysiology in patients with TOF was only recognised in the 1980s and 90s, as the patients who underwent the earliest repairs reached mid-adulthood. Since that time surgical strategies and techniques have changed and it remains unclear whether children who underwent TOF repair in the past two decades will have similar late outcomes to the adults repaired decades earlier. This thesis details an investigation of children during the early years after TOF repair. Two separate, but interlinked prospective studies were conducted, seeking early evidence of post-surgical pathophysiology that is now well recognised in adult patients. The first study looked for early indicators of biventricular compromise and the other for mechanistic connections that might lie behind between pathophysiological associations well documented in adults with repaired TOF. Children with TOF and age and sex- matched healthy controls were carefully studied by echocardiogram at rest and during exercise. Children with TOF were also studied by MRI and underwent cardiopulmonary exercise studies. The results of these investigations show that even while they remain asymptomatic, children with repaired TOF exhibit clear signs of biventricular compromise, electrical disturbance and mechanical dyssynchrony and that exercise both provokes and augments these abnormalities. The work described in this thesis suggests a new hypothesis to explain the intimate connection between mechanical and electrical disturbance after TOF repair. In addition, the early hallmarks of ventricular compromise identified by these investigations may make useful a contribution to the long-term follow- up and clinical management of these patients.