Congenital pericardial defects can be classified according to the location and whether the absence of the pericardium is complete or partial (Tubbs and Yacoub 1968; Faridah and Julsrud 2002; Centola et al. 2009; Southworth and Stevenson 1938). The most frequent defect is the left side absence of the pericardium while right side defects and complete agenesis are quite rare (Abbas et al. 2005; Southworth and Stevenson 1938). Partial defects are rarer but of clinical importance as they can cause myocardial strangulation and death; however, they are usually asymptomatic or paucisymptomatic (Rehkämper et al. 2017; Centola et al. 2009; Sergio et al. 2019).
The pericardium has a mesodermal embryologic origin which starts around the fourth week of development (Faridah and Julsrud 2002). A common cardinal vein divides into the ventral, originating the pneumopericardium, and the dorsal membranes, where the pleuroperitoneal membrane arises by the fifth week (Moore et al. 2018; Kim et al. 2007). These membranes merge with the medial wall of the pleuroperitoneal canal, then the pleural and pericardial cavities become disconnected. Pericardial defects result as a consequence of the failure of pleuropericardial membranes to fuse entirely or as a failure in its formation (Moore et al. 2018; Kim et al. 2007) as well as the premature atrophy of the left common cardinal vein (Brulotte et al. 2007). These defects are usually left-sided, allowing communication between the pericardial and pleural cavities. More rarely, there can be herniation of the left atrium through the pleural cavity (Moore et al. 2018).
Because most cases are asymptomatic, diagnosis tends to be accidental resulting from imaging studies or surgeries searching for other pathologies or during autopsy procedures, which probably means that its real prevalence is underestimated (Khayata et al. 2020; Parmar et al. 2017; Van Son et al. 1993). Furthermore, most partial congenital aplasia is non-diagnosed and joins the statistics of undefined causes of death. Diagnostics for suspected pericardium defects have evolved with the development of high-definition image studies and protocols designed to identify such embryological anomalies (Faridah and Julsrud 2002; Khayata et al. 2020; Parmar et al. 2017).
Compression and strangulation of adjacent structures including the heart and its parts can happen in partial defects, as in this case report, leading to ischemia, necrosis, and death (Baue and Blakemore 1972; Tubbs and Yacoub 1968; Khayata et al. 2020). The absence of the inferior pericardium is rare in adults (Abbas et al. 2005), maybe due to its incompatibility with life, and can be associated with diaphragmatic defects and herniation of abdominal organs into the pericardial sac (Abbas et al. 2005; Centola et al. 2009).
Congenital pericardial defects are usually found as an isolated variation although they can be associated with other cardiac malformations. Thirty percent of patients have cardiac associated defects, such as a bicuspid aortic valve, persistent ductus arteriosus, an atrial septal defect, or tetralogy of Fallot. It can also be a feature of Cantrell’s pentalogy, which is classically composed of defects in the diaphragmatic pericardium, anterior diaphragmatic hernia, supraumbilical abdominal wall defects, agenesis of the lower sternum, and intracardiac malformation; however, it can present partially with different combinations of these conditions. These malformations can also be associated with genetic syndromes, for example, VACTERL syndrome which leads to several anatomical malformations, among them pericardial defects (Rehkämper et al. 2017; Khayata et al. 2020; Parmar et al. 2017).
There are few articles and case reports showing this condition in newborns, which hinders a clear understanding of the epidemiology of this condition. However, pericardium defects are usually associated with other developmental anomalies which can support early diagnosis as well as prevent devasting outcomes. Prenatal perception of an irregular murmur may be the trigger for initiating further investigations by the obstetrician. Although fetal cardiac ultrasound is good for the detection of complex heart diseases that also involve the pericardium, when isolated, its sensitivity is reduced. Fetal sonography is the most common approach to heart conditions in neonates, but although cardiac defects are the most common congenital defects, the sonographic diagnosis of these conditions is not easy, especially when not associated with other features. The addition of other dimensions (e.g., three- and four-dimensional ultrasounds) can also be helpful in the early detection of pericardium abnormalities (Centola et al. 2009; Sohaey and Zwiebel 1996).
Generally, treatment is not required for congenital pericardium defects; however, prophylactic repair in partial defects is required when herniation occurs or is a threat, and in symptomatic patients needing surgical pericardiectomy, pericardioplasty, primary closure, or others, but for these, diagnosis has to be made before it is too late (Shah and Kronzon 2015; Khayata et al. 2020).
