A floating heart: A case of congenital pericardial agenesis associated with atrial septal defect
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/ACVI.ACVI_4_19
Keywords: Atrial septal defect, cardiac magnetic resonance imaging, chest X-ray, congenital absence of pericardium
In this document, we present here a teenager boy with large congenital partial pericardial agenesis, accompanied by atrial septal defect (ASD) and confirmed using cardiac magnetic resonance (CMR) imaging. We also review the diagnostic clues in noninvasive imaging modalities, focusing on our experience of managing such a patient.
A 15-year-old boy, presented with a complaint of palpitation, was referred to our center for further evaluation of right ventricular (RV) enlargement, demonstrated by transthoracic echocardiography (TTE). The patient voluntarily signed the informed consent form. Physical examination revealed apical impulse displacement in chest palpation and brief systolic and diastolic murmurs in cardiac auscultation. Electrocardiogram (ECG) showed right-axis deviation, incomplete right bundle branch block (RBBB), and poor R wave progression in precordial leads [Figure 1]. Complete blood count, as well as all biochemistry tests, was within normal range. Chest radiogram manifested leftward displacement of the cardiac silhouette, hidden right heart border behind spinal column shadow, and pulmonary plethora (shunt vascularity) [Figure 2].
TTE and transesophageal echocardiography (TEE) showed hypermobile heart with teardrop configuration and unusual position of the left ventricular (LV) apex. There were also an RV enlargement and a large-sized (3.0 cm × 2.1 cm) secundum-type ASD, resulting in a left-to-right shunting of blood with a Qp:Qs ratio of 2.2 [Figure 3], [Figure 4], [Figure 5] and Videos 1-3].
Highly suspicious of absence of the pericardium, according to the characteristic findings in TTE and chest X-ray (CXR), chest computed tomography (CT) scan and CMR imaging were performed to confirm the diagnosis. Chest CT scan demonstrated interposition of the lung tissue between the aorta and pulmonary artery [Figure 6]. CMR showed shifting of the heart to left hemithorax with the LV apex pointing posteriorly; furthermore, almost complete agenesis of the left pericardium was manifested using CMR, except for basal parts of LV where the pericardium was seen [Figure 7] and [Figure 8].
As the patient seemed to be a suitable candidate for transcatheter device closure, he was scheduled for ASD device closure in the catheterization laboratory under TEE guidance. Despite great attempts, device deployment was not successful due to improper alignment of the device, slipping into the right atrium. Hence, the procedure was stopped, assuming for surgical repair. During the surgery, ASD was repaired by a Dacron patch; however, knowing the low underlying risk of complications in individuals with large pericardial defects, the pericardium left aside during surgery. Finally, he was discharged from the hospital within 6 days without any complication during hospital stay, nor in the 6 months postoperative follow-up.
Congenital absence of the pericardium is a rare malformation with an incidence of <1 in 10,000 and male-to-female predominance (3:1).[1] However, being asymptomatic in the majority of subjects, the prevalence might be underestimated. These patients are stratified into two categories, complete and partial, such that left-sided pericardial agenesis constitutes 70% of all pericardial defects,[2] followed by right-sided defects and complete bilateral absence of the pericardium, which are less common (17% and 9% of all defects, respectively).[3] By the 5th or 6th week of embryonic life, premature atrophy of the duct of Cuvier results in loss of blood supply to pleuropericardial membrane and therefore pericardial defects that vary greatly in size from small to large.[4] Congenital absence of the pericardium can be isolated or associated with other congenital anomalies in 30%-50% of cases, including ASD, patent ductus arteriosus, mitral valve disease, tetralogy of Fallot, and lung anomalies, such as bronchogenic cysts and sequestrated lungs.[5] Since a large proportion of these patients remain asymptomatic or present with atypical symptoms such as vague chest pain, palpitation, or syncope,[6] maintaining a high suspicion as well as awareness of echocardiographic features is imperative for diagnosis. Characteristic but nonspecific ECG findings consist of right-axis deviation, complete or incomplete RBBB, and poor R wave progression in precordial leads in response to clockwise rotation of the precordial transitional zone. Interestingly, QRS electrical alternans during exercise stress testing may serve as a valuable index to detect excessive translational cardiac movements.[7] CXR features strongly suggestive of diagnosis include levoposition of the cardiac silhouette, lucent area (lung tissue) in the left upper border of the heart between the aortic knob and pulmonary artery, and also straightening of the left cardiac border (snoopy sign).[1] Classic transducer location in the TTE usually does not provide typical views. In this regard, it is better to perform image acquisition to obtain apical windows while the patient is in supine position rather than left decubitus. Parasternal long-axis window shows the major part of RV, while apical four-chamber view demonstrates leftward LV apical displacement and teardrop configuration of the heart, specified by elongated atria and bulbous-shaped ventricles. Exaggerated cardiac motion is another notable finding.[8] Although TTE and CXR could suggest pericardial agenesis, failing to provide manifest diagnosis, more accurate imaging modalities, CMR and CT, are required, not only for delineating the extent and location of pericardial defects but also for predicting the complications.[8] Partial defects, particularly a subpopulation called foramen-type defect, is more likely to become complicated than complete left-sided defects which usually have a benign course. Life-threatening complications include incarceration of myocardium through the defect, compressive effect of pericardial rims on coronary arteries, and consequent myocardial ischemia or infarction.[9] Moreover, torsion of great arteries and traumatic type A aortic dissection have been reported as well, typically arising from exaggerated cardiac motion inside the chest cavity.[10] However, the majority of pericardial defects are still discovered postmortem during autopsies; a variety of symptoms such as atypical chest pain, dyspnea, palpitation, arrhythmia, and syncope have been noticed.[4] Two different treatment approaches for secundum-type ASDs are transcatheter device closure versus surgical closure, as we know it. Since transcatheter device closure as a good surrogate to surgical approach has become the first treatment option, we proposed device closure in the present case with secundum-type ASD but failed. We mentioned the large size of the septal defect and abnormal cardiac position which put catheter maneuvers in difficulty during device deployment as leading causes of early failure in this case. Based on this experience, these patients seem not to be the ideal candidates for ASD device closure regarding to their mal-aligned septum. Patients with hazardous complications or high risk to create complications are considered for surgical treatment. While total bilateral or total unilateral defects are mostly managed conservatively, management of partial left-sided absence of the pericardium is more challenging, usually based on patient's symptoms and size of the defect. Large partial defects do not need surgery as well, considering the low herniation and strangulation risk. Some authors believe that small-to-moderate-sized partial defects, irrespective of symptoms, should undergo surgery while a few others warrant surgery just in symptomatic cases.[8] Surgical approaches include enlargement of the defect to eliminate the risk of herniation, pericardioplasty, or pericardiectomy.[7] Our patient underwent surgery to have his ASD closed, but the pericardial defect was not repaired as it was large enough to be categorized as low risk.
Congenital absence of the pericardium is a rare condition, which diagnosis is necessary to prevent catastrophic complications. Considering the atypical symptoms of this disorder, classic features of CXR and TTE should be kept in mind, especially in patients with associated ASDs whose RV enlargement could be misleadingly justified by ASD, so congenital absence of the pericardium may slip out of the mind. CMR remains the gold standard to confirm the diagnosis in suspects. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
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