Abstract The pericardium is affected in a variety of diseases, both localized to the heart and as part of systemic illnesses Pericardial diseases cause distinctive hemodynamic changes and some of the classic physical findings in cardiology Although clinical overlap is common, most of the cases can be categorized as having pericarditis, pericardial effusion with or without tamponade, and pericardial constriction Other structural abnormalities, such as congenital absence of pericardium and pericardial cysts, are rare This chapter provides an overview of common pericardial diseases in children Keywords Pericardium; pericarditis; recurrent pericarditis; pericardial effusion; bacterial pericarditis; tubercular pericarditis; pericardial constriction; ventricular interdependence; ventricular discordance; pulsus paradoxus; pericardiectomy Introduction The genetic basis for heart and vascular conditions is heterogeneous and includes both heritable and de novo mutations More than 100 genes associated with congenital or progressive cardiovascular abnormalities have thus far been identified In recent years there has been a growing awareness and focus on connective tissue diseases (CTDs) and associated cardiovascular pathology, particularly in children These diseases are hereditary disorders of the body's connective tissues.1 Connective tissues form the extracellular matrix (ECM) that serves to support and bind structures and organs across numerous systems The ECM is a highly organized multimolecular structure that is essential for the normal functioning of organ systems.2 Mutations impacting vascular ECM structure commonly manifest as arterial tortuosity and aneurysm formation, with a risk of subsequent vascular (i.e., aorta and carotid artery) dissection and rupture Furthermore, many connective tissue diseases also impose the risk of structural heart defects, including patent ductus arteriosus, bicuspid aortic valve, coarctation of the aorta, and atrioventricular valve disease Children with connective tissue disorders are prone to aortic aneurysm, dissection, and aortic rupture.3–6 Indeed, aortic dissection is the primary cause of morbidity and mortality in the most common CTDs Although cases of cardiovascular manifestations vary by disease type, mortality following aortic catastrophe in these patients is exceptionally high, with up to 40% of pediatric patients dying immediately and 1% to 3% expiring every hour in the first 24 hours following the initial event Should the child reach the operating room alive, operative mortality as high as 25% has been reported.3 In response to these devastating statistics, various medical and surgical strategies have been developed to mitigate the risk of cardiovascular catastrophe by means of prophylactic intervention Advances in genetic analysis have had a significant impact on the identification and management of children with connective tissue disorders, providing a better understanding of their etiology and phenotypes, improving management strategies, and offering insights into long-term prognosis.1 This chapter provides a description of the most common connective tissue diseases affecting children and their associated cardiovascular pathology The focus is on the most common forms of cardiovascular phenotype (namely proximal aortic pathology and mitral valve disease) to define surgical indications and operative management ... cardiovascular manifestations vary by disease type, mortality following aortic catastrophe in these patients is exceptionally high, with up to 40% of pediatric patients dying immediately and 1% to 3% expiring every hour in the first 24 hours following the initial event