Question of the Week 344
Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease. It is characterized by four distinct anatomic features described by Etienne Fallot in 1888 including the following: 1) anterior malalignment ventricular septal defect, 2) right ventricular outflow tract obstruction, 3) overriding aorta, and 4) right ventricular hypertrophy. The anterior malalignment of the conoventricular septum produces the spectrum of disease which can range in severity from an asymptomatic neonate to one that is severely cyanotic and has ductal-dependent physiology. The severity of the right ventricular outflow tract obstruction (RVOTO) determines the degree of cyanosis. Most commonly, cyanosis is mild at birth and gradually progresses with age as there is an increase in infundibular hypertrophy. By six to twelve months of life, the cyanosis tends to be significant. A smaller percentage of patients with TOF and pulmonary stenosis (PS) have marked cyanosis soon after birth. In this population, the RVOTO is often secondary to a hypoplastic pulmonary valve annulus and the cyanosis is constant because of the fixed nature of the obstruction to pulmonary blood flow.
Traditionally, there have been two surgical approaches to Tetralogy of Fallot with pulmonary stenosis including primary complete repair versus a two-stage repair with an aortopulmonary shunt followed by a complete repair either with a transannular patch or a valve sparing procedure. At present, the ideal age for complete correction of TOF remains elusive and is highly institution dependent. Historically, the approach to a neonate or infant with TOF has been to wait for surgical repair until symptoms develop or until the infant was older. The morbidity and mortality of the operation was thought to be less in an older patient.
An early primary repair restores a normal circulation, which can diminish the deleterious physiologic effects of TOF to the heart, lungs, brain and other organ systems. Studies have shown that normalizing pulmonary arterial flow early optimizes pulmonary angiogenesis and alveolar development. Additionally, due to the unrestrictive anterior malalignment VSD, the right ventricle is exposed to systemic pressure resulting in right ventricular hypertrophy and decreased compliance. There is some evidence that left ventricular function is compromised as well when repair is delayed. There is a lower incidence of ventricular arrhythmias among children repaired at younger ages. An additional benefit of primary repair is the avoidance of aortopulmonary shunt related complications such as pulmonary artery distortion, shunt thrombosis, congestive heart failure, and/or pulmonary vascular disease. Thus, answer choice B and D are incorrect. At present, there is essentially no contraindication to early primary repair. Historically, indications for delayed repair include an anomalous coronary artery crossing the right ventricular outflow tract, hypoplastic or discontinuous pulmonary arteries, and multiple VSDs.
Despite success with early primary surgical repair of TOF, a two-stage repair remains favored at many institutions. Thus, answer choice C is correct. This is primarily the result of institutional culture, experience, and outcomes. An additional reason to delay complete repair in favor of two-stage repair revolves around the physiologic sequelae of a transannular patch over time, which includes increased ventricular dimensions, decreased ventricular function, decreased exercise capacity, arrhythmias, heart failure, and sudden cardiac death. However, there is insufficient evidence to support the idea that a two-stage repair decreases the risk of later pulmonary valve replacement. The largest published series describing late-phase events in adults with repaired TOF demonstrated that the risk of later reoperation is independent of the type of initial repair. Likewise, there is no evidence to suggest that initial palliation with an aortopulmonary shunt results in a decreased incidence of later complete repair with a transannular patch. Thus, answer choice A is incorrect.
Al Habib et al. analyzed contemporary patterns of management of TOF/PS using The Society of Thoracic Surgeons database and demonstrated that procedure type in neonates was equally divided between primary repair and a two-stage approach. In addition, use of a transannular patch was the most prevalent surgical technique for both primary repair and for a 2-stage repair. The discharge mortality from TOF repair in neonates was not significantly different between palliation (6.2%) and primary repair (7.8%). Thus, answer choice B is incorrect. Kanter et al. examined outcomes in neonates with symptomatic TOF who underwent either a primary repair or a two-stage repair and found equivalent mortality rates. Additionally, the study demonstrated that shunted patients had fewer transannular patch repairs but this has not been a consistent finding across studies. Antegrade pulmonary blood flow is the primary stimulus for growth of right ventricular outflow tract structures and thus a palliative aortopulmonary shunt would perpetuate reduced pulmonary flow. Thus, the expectation would be that the pulmonary valve would become smaller with time in patients with an aortopulmonary shunt and increase the need for a transannular patch. Nonetheless, the debate about the effect of early primary repair with a transannular patch on the growth of the pulmonary valve annulus remains a hot topic.
References
1. Barratt-Boyes BG, Neutze JM. Primary repair of Tetralogy of Fallot in infancy using profound hypothermia with circulatory arrest and limited cardiopulmonary bypass: a comparison with conventional two stage management. Ann Surg. 1973; 178: 406–411.
2. Castaneda AR, Freed MD, Williams RG, Norwood WI. Repair of Tetralogy of Fallot in infancy: early and late results. J Thorac Cardiovasc Surg. 1977; 74: 372–381.
3. Di Donato RM, Jonas RA, Lang P, Rome JJ, Mayer JE Jr, Castaneda AR. Neonatal repair of tetralogy of Fallot with and without pulmonary atresia. J Thorac Cardiovasc Surg. 1991; 101(1):126-137. PMID: 1986154.
4. Sullivan ID, Presbitero P, Gooch VM, Arura E, Deanfield JE. Is ventricular arrhythmia in repaired tetralogy of Fallot an effect of operation or a consequence of the course of the disease? A prospective study. Br Heart J. 1987; 58: 40–44.
5. Hegerty A, Anderson RH, Deanfield JE. Myocardial fibrosis in tetralogy of Fallot: effect of surgery or part of the natural history? Br Heart J. 1988; 59: 123.
6. Jonas RA. Early primary repair of tetralogy of Fallot. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2009: 39-47.
7. Parry AJ, McElhinney DB, Kung GC, Reddy M, Brook MM, Hanley FL. Elective Primary Repair of Acyanotic Tetralogy of Fallot in Early Infancy: Overall Outcome and Impact on the Pulmonary Valve. J Am Coll Cardiol. 2000; 36: 2279–2283.
8. Kirklin JW, Blackstone EH, Pacifico AD, Brown RN, Bargeron LM Jr. Routine primary repair vs two stage repair of tetralogy of Fallot. Circulation. 1979; 60: 373–386.
9. Vobecky SJ, Williams WG, Trusler GA, et al. Survival analysis of infants under age 18 months presenting with tetralogy of Fallot. Ann Thorac Surg. 1993; 56: 944–949.
10. Van Arsdell GS, Maharaj GS, Tom J et al. What is the Optimal Age for Repair of Tetralogy of Fallot? Circulation. 2000;102:Iii-123–129.
11. Gladman G, McCrindle BW, Williams WG, et al. The modified Blalock-Taussig shunt: clinical impact and morbidity in Fallot’s tetralogy in the current era. J Thorac Cardiovasc Surg. 1997; 114: 25–30.
12. Uva MS, Chardigny C, Galetti L, et al. Surgery for tetralogy of Fallot at less than six months of age. Is palliation "old-fashioned”? Eur J Cardiothorac Surg. 1995; 9(8): 453–460.
13. Lee CH, Kwak JG, Lee C. Primary repair of symptomatic neonates with tetralogy of Fallot with or without pulmonary atresia. Korean J Pediatr. 2014; 57(1): 19-25. doi: 10.3345/kjp.2014.57.1.19.
14. Al Habib HF, Jacobs JP, Mavroudis C, et al. Contemporary patterns of management of tetralogy of Fallot: data from the Society of Thoracic Surgeons Database. Ann Thorac Surg. 2010; 90(3): 813-819.
15. Kanter KR, Kogon BE, Kirshbom PM, Carlock PR. Symptomatic neonatal tetralogy of Fallot: repair or shunt? Ann Thorac Surg. 2010; 89(3): 858-863.
16. Guyton RA, Owens JE, Waumett JD, Dooley KJ, Hatcher CR Jr, Williams WH. The Blalock-Taussig shunt. Low risk, effective palliation, and pulmonary artery growth. J Thorac Cardiovasc Surg. 1983; 85(6): 917-922.
17. Pigula FA, Khalil PN, Mayer JE, del Nido PJ, Jonas RA. Repair of Tetralogy of Fallot in Neonates and Young Infants. Circulation. 1999; 100: II-157–161.
Traditionally, there have been two surgical approaches to Tetralogy of Fallot with pulmonary stenosis including primary complete repair versus a two-stage repair with an aortopulmonary shunt followed by a complete repair either with a transannular patch or a valve sparing procedure. At present, the ideal age for complete correction of TOF remains elusive and is highly institution dependent. Historically, the approach to a neonate or infant with TOF has been to wait for surgical repair until symptoms develop or until the infant was older. The morbidity and mortality of the operation was thought to be less in an older patient.
An early primary repair restores a normal circulation, which can diminish the deleterious physiologic effects of TOF to the heart, lungs, brain and other organ systems. Studies have shown that normalizing pulmonary arterial flow early optimizes pulmonary angiogenesis and alveolar development. Additionally, due to the unrestrictive anterior malalignment VSD, the right ventricle is exposed to systemic pressure resulting in right ventricular hypertrophy and decreased compliance. There is some evidence that left ventricular function is compromised as well when repair is delayed. There is a lower incidence of ventricular arrhythmias among children repaired at younger ages. An additional benefit of primary repair is the avoidance of aortopulmonary shunt related complications such as pulmonary artery distortion, shunt thrombosis, congestive heart failure, and/or pulmonary vascular disease. Thus, answer choice B and D are incorrect. At present, there is essentially no contraindication to early primary repair. Historically, indications for delayed repair include an anomalous coronary artery crossing the right ventricular outflow tract, hypoplastic or discontinuous pulmonary arteries, and multiple VSDs.
Despite success with early primary surgical repair of TOF, a two-stage repair remains favored at many institutions. Thus, answer choice C is correct. This is primarily the result of institutional culture, experience, and outcomes. An additional reason to delay complete repair in favor of two-stage repair revolves around the physiologic sequelae of a transannular patch over time, which includes increased ventricular dimensions, decreased ventricular function, decreased exercise capacity, arrhythmias, heart failure, and sudden cardiac death. However, there is insufficient evidence to support the idea that a two-stage repair decreases the risk of later pulmonary valve replacement. The largest published series describing late-phase events in adults with repaired TOF demonstrated that the risk of later reoperation is independent of the type of initial repair. Likewise, there is no evidence to suggest that initial palliation with an aortopulmonary shunt results in a decreased incidence of later complete repair with a transannular patch. Thus, answer choice A is incorrect.
Al Habib et al. analyzed contemporary patterns of management of TOF/PS using The Society of Thoracic Surgeons database and demonstrated that procedure type in neonates was equally divided between primary repair and a two-stage approach. In addition, use of a transannular patch was the most prevalent surgical technique for both primary repair and for a 2-stage repair. The discharge mortality from TOF repair in neonates was not significantly different between palliation (6.2%) and primary repair (7.8%). Thus, answer choice B is incorrect. Kanter et al. examined outcomes in neonates with symptomatic TOF who underwent either a primary repair or a two-stage repair and found equivalent mortality rates. Additionally, the study demonstrated that shunted patients had fewer transannular patch repairs but this has not been a consistent finding across studies. Antegrade pulmonary blood flow is the primary stimulus for growth of right ventricular outflow tract structures and thus a palliative aortopulmonary shunt would perpetuate reduced pulmonary flow. Thus, the expectation would be that the pulmonary valve would become smaller with time in patients with an aortopulmonary shunt and increase the need for a transannular patch. Nonetheless, the debate about the effect of early primary repair with a transannular patch on the growth of the pulmonary valve annulus remains a hot topic.
References
1. Barratt-Boyes BG, Neutze JM. Primary repair of Tetralogy of Fallot in infancy using profound hypothermia with circulatory arrest and limited cardiopulmonary bypass: a comparison with conventional two stage management. Ann Surg. 1973; 178: 406–411.
2. Castaneda AR, Freed MD, Williams RG, Norwood WI. Repair of Tetralogy of Fallot in infancy: early and late results. J Thorac Cardiovasc Surg. 1977; 74: 372–381.
3. Di Donato RM, Jonas RA, Lang P, Rome JJ, Mayer JE Jr, Castaneda AR. Neonatal repair of tetralogy of Fallot with and without pulmonary atresia. J Thorac Cardiovasc Surg. 1991; 101(1):126-137. PMID: 1986154.
4. Sullivan ID, Presbitero P, Gooch VM, Arura E, Deanfield JE. Is ventricular arrhythmia in repaired tetralogy of Fallot an effect of operation or a consequence of the course of the disease? A prospective study. Br Heart J. 1987; 58: 40–44.
5. Hegerty A, Anderson RH, Deanfield JE. Myocardial fibrosis in tetralogy of Fallot: effect of surgery or part of the natural history? Br Heart J. 1988; 59: 123.
6. Jonas RA. Early primary repair of tetralogy of Fallot. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2009: 39-47.
7. Parry AJ, McElhinney DB, Kung GC, Reddy M, Brook MM, Hanley FL. Elective Primary Repair of Acyanotic Tetralogy of Fallot in Early Infancy: Overall Outcome and Impact on the Pulmonary Valve. J Am Coll Cardiol. 2000; 36: 2279–2283.
8. Kirklin JW, Blackstone EH, Pacifico AD, Brown RN, Bargeron LM Jr. Routine primary repair vs two stage repair of tetralogy of Fallot. Circulation. 1979; 60: 373–386.
9. Vobecky SJ, Williams WG, Trusler GA, et al. Survival analysis of infants under age 18 months presenting with tetralogy of Fallot. Ann Thorac Surg. 1993; 56: 944–949.
10. Van Arsdell GS, Maharaj GS, Tom J et al. What is the Optimal Age for Repair of Tetralogy of Fallot? Circulation. 2000;102:Iii-123–129.
11. Gladman G, McCrindle BW, Williams WG, et al. The modified Blalock-Taussig shunt: clinical impact and morbidity in Fallot’s tetralogy in the current era. J Thorac Cardiovasc Surg. 1997; 114: 25–30.
12. Uva MS, Chardigny C, Galetti L, et al. Surgery for tetralogy of Fallot at less than six months of age. Is palliation "old-fashioned”? Eur J Cardiothorac Surg. 1995; 9(8): 453–460.
13. Lee CH, Kwak JG, Lee C. Primary repair of symptomatic neonates with tetralogy of Fallot with or without pulmonary atresia. Korean J Pediatr. 2014; 57(1): 19-25. doi: 10.3345/kjp.2014.57.1.19.
14. Al Habib HF, Jacobs JP, Mavroudis C, et al. Contemporary patterns of management of tetralogy of Fallot: data from the Society of Thoracic Surgeons Database. Ann Thorac Surg. 2010; 90(3): 813-819.
15. Kanter KR, Kogon BE, Kirshbom PM, Carlock PR. Symptomatic neonatal tetralogy of Fallot: repair or shunt? Ann Thorac Surg. 2010; 89(3): 858-863.
16. Guyton RA, Owens JE, Waumett JD, Dooley KJ, Hatcher CR Jr, Williams WH. The Blalock-Taussig shunt. Low risk, effective palliation, and pulmonary artery growth. J Thorac Cardiovasc Surg. 1983; 85(6): 917-922.
17. Pigula FA, Khalil PN, Mayer JE, del Nido PJ, Jonas RA. Repair of Tetralogy of Fallot in Neonates and Young Infants. Circulation. 1999; 100: II-157–161.
