*Hypoplastic Left Heart Syndrome DOI: http://dx.doi.org/10.5772/intechopen.104723*

#### **Figure 3.**

*Variations in the condition of the mitral valve in hearts with HLHS. (a) Normal mitral valve, (b) normally configured but miniaturized mitral valve with slightly shortened and mildly thickened tension apparatus and mild diffuse endocardial fibroelastosis, (c) stenotic and dysplastic mitral valve in a heart with severe hypoplasia of the left ventricle and prominent endocardial fibroelastosis, (d) floor of the left atrium and an imperforate mitral valve, and (e) completely muscular floor of the left atrium without evidence of a mitral valve in a heart with mitral valve agenesis.*

#### **Figure 4.**

*Aortic valve stenosis and atresia in the setting of HLHS. (a) Normal aortic valve, (b) tricuspid, stenotic and dysplastic aortic valve, and c) aortic valvar membranous atresia, mitral valve stenosis, and thick endocardial fibroelastosis.*

they do not meet the traditional definition. However, these types of hearts (right-dominant unbalanced AVSD and DORV) have been described as **HLHS variants** in addition to their hypoplastic left ventricles they had one or more of the expected left-sided obstructive

#### **Figure 5.**

*Supracardiac great arteries and the right side of specimens with HLHS. (a) Mildly hypoplastic ascending aorta and large arterial duct, (b) hypoplastic ascending aorta and proximal aortic arch, coarctation of the aorta at the level of a large arterial duct, (c) enlarged right heart with hypertrophy of the right ventricle and an atrial septal defect.*

#### **Figure 6.**

*Right and left heart anatomy of a heart with premature closure of the oval fossa, and a specimen with a levoatriocardinal vein. (a) Septal surface of the right atrium illustrating the prematurely closed oval fossa, (b) dysplastic and stenotic mitral valve, (c) non-apex forming hypoplastic left ventricle with pronounced endocardial fibroelastosis, (d levoatriocardinal vein connecting the left atrium to the left innominate vein.*

#### **Figure 7.**

*Specimens with hypoplastic left ventricles that do not meet the criteria of HLHS. (a) Aortic stenosis and intact ventricular septum, (b) right-dominant, unbalanced AVSD, and an atrial septal defect, (c) right ventricle view, DORV and a ventricular septal defect, (d) left ventricular view of C showing the hypoplastic left ventricle, ventricular septal defect, and the stenotic mitral valve.*

features seen in classical HLHS such as aortic stenosis/atresia or mitral valve atresia/ stenosis, hypoplastic aorta or coarctation of the aorta. Hearts with a DORV or a rightdominant AVSD but had only aortic obstruction and a hypoplastic left ventricle that is physiology inadequate should not be classified as HLHS variants just because they require single ventricle surgical palliation such as the Norwood, bidirectional Glenn, and the Fontan procedures. The classifications of these types of hearts continue to be unsettled, and this is a reason the classification of HLHS variants needs to be based not only on morphology but also on genetic studies, and not on the need for single ventricle surgical palliation or describing them as HLHS variants just to make the cardiac malformations easier to understand for the clinician or others not trained in pediatric cardiology. Doing this may skew forthcoming studies concerning DORV, right-dominant unbalanced AVSD, and HLHS [13].
