Congenital Absence of the Pericardium
Introduction
Congenital absence of the pericardium (CAP) is one of the rarest cardiac congenital anomalies. It can occur as a complete absence of the entire pericardium, absence of the right or left portion of the pericardium or a partial, foramen-like defect of the right or left pericardium (LP).1., 2. While the majority of cases are clinically silent, multiple reports associate CAP with symptomatic presentation. The most feared complication of CAP is sudden cardiac death (SCD) due to cardiac strangulation across a partial defect of the LP.1., 3. Given its rare occurrence, most clinicians and imaging specialists will have little experience with this condition and may fail to recognize it on thoracic or cardiac studies.2., 4. Thus, the purpose of this review is to highlight the common clinical and multimodality imaging features associated with this anomaly and suggest a management algorithm.
CAP was first described in 1559 by the Italian anatomist Realdus Columbus. Over the next 400 plus years, CAP has been identified at autopsy or incidentally during surgery. The prevalence of CAP ranges from 0.007% to 0.015% in autopsy reports1 to 0.044% in a surgical case series.2 One of the earliest descriptions of CAP came from Versé in 1909, finding 2 cases in a series of 13,000 autopsies. Similarly, in 1938 Southworth and Stevenson1 reported a single case of absent LP, in a series of 14,000 autopsies at Johns Hopkins Hospital. A slightly higher prevalence of CAP has been found in more contemporary surgical reports with 15 cases described out of 34,000 cardiothoracic surgeries at the Mayo Clinic.2 Based on case reports, it is generally thought that this lesion occurs more commonly in males than females with a 3:1 ratio.1., 5. However conflicting data show no clear gender predominance. In the surgical series from the Mayo Clinic, 7 of the 15 patients were males and in a report of symptomatic patients with CAP, 3 out of 10 were males.2., 6. CAP is typically an isolated lesion, but has been incidentally found in the setting of other congenital cardiac abnormalities2.
The vast majority of cases of CAP involve partial or complete absence of the LP. Right-sided defects are exceedingly rare. In the 1938 autopsy series from Johns Hopkins Hospital, 52 definitive cases were identified and reviewed. Among those classified as definitive, 76% had complete absence of the LP and 24% had partial absence or a foramen type defect of the LP. Right-sided or bilateral defects were only observed in 7 cases and associated with multiple birth defects. Concordantly, in the surgical series from the Mayo Clinic, 12 of the 15 cases had complete or partial defects of the LP. Among the 3 other cases, one had a partial defect of the right pericardium, one a partial defect of the anterior pericardium and one had absence of the entire pericardium.
The majority of CAP cases reported in the literature were incidentally found in asymptomatic individuals. Some have been identified in the course of evaluating cardiac symptoms. The most common associated complaint is atypical, sharp or stabbing, and often left-sided positional chest pain.6 Exertional symptoms are not usually reported. Except for one case of cardiac herniation between the pulmonary ligament and the diaphragm,7 the mechanism of pain in those with complete absence of the LP is not well understood. In the setting of partial defects, herniation of the left atrial appendage and left ventricular apex leading to regional ischemia has been documented.8., 9., 10. The most dramatic and feared presentation is sudden death due to cardiac strangulation across a left-sided partial defect, although to date, only about 3 cases have been reported in the literature.3., 5. Surgical treatment is usually recommended for those with significant symptoms or obvious herniation.6 Two reports in the literature implicate CAP with severe tricuspid regurgitation due to leftward and posterior displacement of the heart, which stretches the anterior right ventricular wall.11., 12. However, in one of these cases a large defect in the anterior leaflet of the tricuspid valve was found during the operation.12 Thus congenital absence of the pericardium could have contributed, but was not the sole etiology of the regurgitation.
Section snippets
Clinical and radiological diagnosis
In 1915 the Canadian physician Maude Abbott proposed that the diagnosis of complete absence of the LP could be made clinically based on: (1) increased cardiac mobility, (2) unexplained cardiac enlargement and (3) leftward shift of the heart.1., 13. She predicted that cases of partial defects were impossible to diagnose clinically. Clinical signs have not proven sufficient to make the diagnosis. At a minimum a combination of physical exam, electrocardiography (ECG) and chest radiograph is needed
Appearance of the pericardium on non-invasive imaging
With the advent of echocardiography, cardiac computed tomography (CCT) and cardiac magnetic resonance imaging (CMR) there are now non-invasive diagnostic tools to identify and better characterize CAP. However, visualization of the pericardium on non-invasive imaging is not an insignificant task. The pericardium consists of two adjacent layers, which are separated by a normally invisible trace amount of fluid. The thickness of the combined visceral and parietal pericardium is usually <2 mm.
General principles and imaging technique
CCT and CMR have emerged as important modalities for advanced imaging of the pericardium. Accuracy for the diagnosis of CAP is probably comparable between the two modalities. Selection of one versus the other will depend on institutional availability, expertise and clinical scenario. CMR provides a more comprehensive evaluation, which includes direct pericardial visualization and assessment of cardiac function without exposure to ionizing radiation. On the other hand, CCT is a much faster
General diagnostic approach and management
The diagnostic approach to CAP will vary according to the clinical scenario (Fig. 8). CAP may be incidentally identified or suspected during routine screening evaluation or on non-cardiac testing, such as chest CT or CMR. It may also be detected in the course of an evaluation for chest pain or other cardiac symptoms. In the case of the asymptomatic individual with suspected CAP based on the physical exam, ECG, or chest x-ray, a transthoracic echocardiogram may suffice to support the clinical
Summary
CAP is a rare cardiac abnormality that is typically clinically silent, but has been associated with cardiac related symptoms in some individuals. With the advent of widespread thoracic and cardiac imaging, detection in asymptomatic individuals has increased. Partial defects of the pericardium, especially partial LP absence, can be associated with morbidity and mortality by way of cardiac herniation. The diagnosis of CAP can be made by a combination of clinical and non-invasive imaging findings,
Conflict of interest
The author declares no conflict of interest.
Acknowledgment
The authors want to thank Vislava Tylman, MLS for her assistance obtaining hard copies of reference articles.
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Cited by (25)
A case report of congenital absence of the pericardium that was diagnosed by cardiac computed tomography angiogram (CCTA)
2022, Radiology Case ReportsCitation Excerpt :Partial pericardial defect can be seen on the x-ray as a bulge through the heart's contour during diastole. Echocardiograms can detect the increased cardiac mobility and abnormal position and orientation of the heart [21]. Chest CTA and cardiac magnetic resonance imaging (CMR) provide a detailed description of the pericardium and thus are superior to the echocardiogram in that aspect [22].
Congenital Absence of the Pericardium: Pearls and Pitfalls
2022, Seminars in Ultrasound, CT and MRICitation Excerpt :The most commonly recognized finding is interposed lung between the aorta and pulmonary artery where there is normally a superior pericardial recess.10 Typical frontal chest radiographic findings include leftward shift of the heart with an elongated left heart border (Snoopy sign), absent visualization of right heart border (obscured by the spine), maintenance of midline position of trachea, prominence of the main pulmonary artery, sharp AP window and radiolucency between the heart and the diaphragm4,5,8 (Figs. 1 and 2A). Focal lateral bulging of the upper left heart border due to left atrial appendage bulging/herniation may be seen in a partial left pericardial defect (Fig. 3A).4,5
Cardiac Strangulation Due to Partial Pericardial Defect Presenting as Acute Myocardial Infarction
2021, JACC: Case ReportsCitation Excerpt :In addition, among the 34,000 patients who underwent cardiovascular surgery at the Mayo Clinic, 15 cases of a partial or complete absence of the pericardium were observed, none of which were diagnosed preoperatively (3). The Johns Hopkins Hospital reported that 24% of pericardial defect cases are partial defects (4). Pericardial defects are often asymptomatic.
Clinical Update in Pericardial Diseases
2019, Journal of Cardiothoracic and Vascular AnesthesiaCitation Excerpt :For symptomatic patients or those with obvious herniation, surgical intervention is warranted. Diagnosis of this anomaly may be suggested by a laterally displaced apical impulse and by characteristic findings on echocardiography including RV dilation, increased mobility of the heart, posterior orientation of the apex, elongated atria with teardrop-shaped ventricles, and tricuspid regurgitation due to annular dilation.1,6 Computed tomography (CT) and CMR provide a more comprehensive evaluation, and each modality can identify the absence of the pericardial layer and other corroborating findings such as levorotation and interposition of lung tissue in places normally covered by pericardium.1,6
Advances in Echocardiography
2018, Progress in Cardiovascular DiseasesMultimodality Imaging Approach Evaluation of the Congenital Pericardial Defect: a Contemporary Review
2023, Current Cardiology Reports
Statement of Conflict of Interest: see page 404.