Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS) is a spectrum of congenital heart disease (CHD) characterized by significant hypoplasia or atresia of the aortic valve and concomitant mitral hypoplasia with underdevelopment of the left ventricle, normally related great vessels, and hypoplasia of the ascending aorta and arch (Tchervenkov, Jacobs, Tahta, Ann Thorac Surg 69(4 Suppl):S170–S179, 2000; Gobergs, Salputra, Lubaua, Acta Med Litu 23(2):86–98, 2016). Clinically the anatomical diagnosis is distinguished by the status of the mitral and the aortic valve (hypoplasia versus atresia). At one end of the spectrum is HLHS with aortic atresia and mitral atresia (AA-MA) which is usually associated with severely hypoplastic left ventricular cavity, and on the other end is aortic stenosis and mitral stenosis (AS-MS) where the left ventricle is usually larger in size. In between the two, there is the aortic atresia – mitral stenosis subtype (Tchervenkov, Jacobs, Tahta, Ann Thorac Surg 69(4 Suppl):S170–S179, 2000). If left untreated, this condition is universally fatal. Advances in surgical and medical management have resulted in improvement in survival (Brosig, Mussatto, Hoffman, Hoffmann, Dasgupta, Tweddell, et al., Pediatr Cardiol 34(7):1597–1604, 2013; Frommelt, Sheridan, Mussatto, Hoffman, Ghanayem, Frommelt, et al., J Am Soc Echocardiogr 20(12):1364–1373, 2007; Ghanayem, Cava, Jaquiss, Tweddell, Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 7:32–38, 2004). Despite that, the mortality for HLHS remains high even with optimal surgical and medical management (Tweddell, Hoffman, Mussatto, Fedderly, Berger, Jaquiss, et al., Circulation 106(12 Suppl 1):I82–I89, 2002). In this chapter, we will discuss the epidemiology and etiology of HLHS; we will then evaluate the anatomical considerations in HLHS, followed by the presentation of HLHS, the diagnosis, management, and outcomes. We will briefly elude to long-term outcomes in the adult with HLHS although that is discussed in more detail in Part VIII, “Adult Congenital Heart Disease.”