therefore the threshold for intervention is slightly higher at 4.5 cm Additionally, aneurysmal growth of greater than 0.5 cm/year warrants surgical intervention However, regardless of type in these children, those with a concerning family history of aortic catastrophe and severe craniofacial features may warrant earlier intervention.25 Box 58.2 Guidelines for Routine Clinical Care in Children With Loeys-Dietz Syndrome2 Yearly echocardiography; shorter intervals depending on the extent of aortic disease Angiotensin-receptor blockade, β-blocker, or angiotensin-converting enzyme inhibitor for strict blood pressure control Avoidance of contact/competitive sports, isometric exercises, strenuous exercise, blows to head/chest Avoidance of stimulants and vasoconstrictors Subacute bacterial endocarditis prophylaxis in those with artificial valves Cardiac surgery consultation when surgical thresholds for intervention are approaching Ehlers-Danlos Syndrome EDS is most commonly inherited in an autosomal dominant pattern, with an estimated prevalence of 1 in 5000 individuals.26 Historically, the Villefranche nosology has been widely used as the standard clinical classification system for EDS; it describes the six major subtypes of the syndrome.11,27 In 2017, given the extensive research in connective tissue diseases as well as advances in gene sequencing, a new classification system was developed to include newly defined subtypes of EDS.27 In the 2017 classification system, 13 subtypes have been recognized, maintaining a clinical classification system to define subtypes by phenotype All subtypes include the basic clinical hallmarks of EDS, which include joint hypermobility, skin hyperextensibility, and tissue fragility Vascular EDS, also known as type IV EDS, results from mutations in the COL3A1 gene, which affects type III collagen synthesis and are inherited in an autosomal dominant pattern Characteristic features of vascular EDS include thin translucent skin; characteristic facial appearance (large eyes, small chin, sunken cheeks, thin nose and lips, lobeless ears); and vascular fragility demonstrated by extensive bruising, easy bleeding, and spontaneous arterial, intestinal, or uterine rupture.1,3,28–30 Cardiovascular manifestations of EDS include arterial aneurysms at any location throughout the arterial tree, mitral valve dysfunction, and venous malformations The diagnosis of type IV EDS is based on clinical findings and confirmed by genetic analysis for the causative mutation or by identification of abnormal type III collagen synthesis Major criteria for diagnosis include a family history of vascular EDS with a documented causative variant in the COL3A1 gene, arterial rupture or dissection at a young age (