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Ann Thorac Surg 2000;69:1209-1215
© 2000 The Society of Thoracic Surgeons

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ORIGINAL ARTICLES: CARDIOVASCULAR

Isolated congenital absence of the pericardium: clinical presentation, diagnosis, and management

^a Department of Medicine, Toronto Hospital, Toronto, Ontario, Canada
^b Department of Cardiac Imaging, Toronto Hospital, Toronto, Ontario, Canada
^c Department of Cardiothoracic Surgery, Toronto Hospital, Toronto, Ontario, Canada
^d Division of Cardiology, The Hospital for Sick Children, University of Toronto Congenital Cardiac Centre for Adults, Toronto, Ontario, Canada

Address reprint requests to Dr Gatzoulis, Royal Brompton Hospital, Sydney St, London SW3 6NP, England
e-mail: m.gatzoulis{at}rbh.nthames.nhs.uk

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. Congenital absence of the pericardium (CAP) is a rare clinical entity.

Methods. We identified from the two hospital databases all patients with isolated CAP, reviewed their data, and invited them for prospective clinical evaluation with electrocardiography, chest x-ray findings (CXR), echocardiography, and magnetic resonance imaging (MRI).

Results. Ten patients (3 males, 7 females) presented at a median age of 21 years (range, 2–53 years) with paroxysmal stabbing chest pain, largely nonexertional (9), and heart murmur with an abnormal CXR (1). Three patients had partial and 7 had complete CAP (all 7 had marked lateral displacement of the cardiac apex). CXR combined with MRI were key to establishing the diagnosis; a "tongue" of lung tissue interposing between the main pulmonary artery and aorta was the most consistent diagnostic feature. Four patients underwent pericardioplasty, 3 for debilitating symptoms and 1 for left atrial appendage herniation, followed by improvement or resolution of symptoms. At a mean of 10.5 years from presentation all patients were alive. No complications were seen in the nonsurgical group.

Conclusions. Isolated CAP has a common presentation pattern with periodic stabbing chest pain mimicking coronary artery disease. CXR and MRI are required for definitive diagnosis. Symptomatic patients with the complete form may benefit from pericardioplasty.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Isolated congenital absence of the pericardium (CAP) encompasses a range of congenital pericardial defects from a small foramen in the pericardium to a complete absence of the entire pericardium [1]. Despite its rarity, CAP has been reported for more than 400 years [2]. Most previous reports have referred to patients in whom the diagnosis of partial or complete absence of pericardium was made incidentally at postmortem examination [3], during other intrathoracic operations [4], or from abnormal chest radiograms [5]. Isolated case reports have recognized that CAP and its complications may be associated with symptoms, some of which may be life threatening.

It has been our impression that there is a distinct form of isolated CAP often presenting with disabling symptoms and a fairly constant presentation pattern that may mimic coronary artery disease. We present our experience of morphologic features, presentation, and outcome of patients with isolated absence of pericardium at the University of Toronto Congenital Cardiac Centre for Adults (UTCCCA), Toronto Hospital and The Hospital for Sick Children, both in Toronto.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Departmental databases were interrogated to identify all patients with a diagnosis of CAP seen either at the UTCCCA, Toronto Hospital, or at the Division of Cardiology, The Hospital for Sick Children, Toronto. Patients who had been diagnosed incidentally during operation or postmortem and patients with other congenital cardiac disease were excluded. Demographics, available clinical, electrocardiographic, radiographic, and surgical data were reviewed and recorded. Patients with a confirmed diagnosis of isolated CAP were invited formally to participate in the study, which was approved by the Toronto Hospital Human Ethics Committee. Our prospective protocol included outpatient clinic assessment with history, clinical examination, 12-lead electrocardiogram (ECG), chest x-ray findings (CXR), transthoracic echocardiogram, and magnetic resonance imaging (MRI). Patients were asked to grade their current symptomatic status compared with symptoms at presentation as follows: 1 = worse, 2 = much worse, 3 = same, 4 = better, 5 = much better, and 6 = symptoms resolved.

CXRs were obtained with patients standing in standard posteroanterior views. The following parameters (Fig 1) were recorded if present: levoposition of the heart; loss of the right heart border (hidden by the spine); prominence of the pulmonary artery segment; a "tongue" of lung interposing between the aorta and the main pulmonary artery; irregular left heart border with or without a protruding left atrial appendage; and interposition of lung between the left hemidiaphragm and inferior border of the heart.

View larger version (138K): [in this window] [in a new window]   Fig 1. Characteristic posteroanterior radiograph from a patient with complete congenital absence of left pericardium. Note the marked levoposition of the cardiac silhouette, loss of right heart border, prominent main pulmonary artery, with borderline irregularities of the upper left heart border, and a "tongue" of lung tissue interposing between the main pulmonary artery and aorta (arrow). The latter was the most common feature in patients with complete and partial absence of pericardium, seen also on magnetic resonance imaging.

Transthoracic echocardiograms were performed employing laterally displaced apical windows, as required. Lateral placement of the transducer was also necessary for parasternal axis views in some patients. Echocardiography excluded coexisting structural cardiac disease and recorded the presence of ventricular dilation, ventricular dysfunction, and paradoxical septal motion when present.

The MRI technique utilized was an ECG-triggered, T1-weighted spin-echo (T1W S-E) sequence in the coronal and axial planes, with 5 mm continuous slices using interlined acquisitions. Additional multiple continuous 10 mm cine-gradient echo images through the entire heart also were acquired. Imaging factors included the following: 245 x 192 matrix, 2 NEX, superior/inferior saturation pulse, respiratory compensation, 24 cm field of view. The following indicators (Figs 2–4) were recorded when present: heart completely fallen into the left hemithorax; main pulmonary artery and left atrial appendage extending far beyond the mediastinal margins; lung between the aorta and main pulmonary artery; lung between the inferior face of the heart and the diaphragm; bulging and elevated cardiac apex; left ventricular myocardial crease, suggestive of an apical pericardial defect.

View larger version (131K): [in this window] [in a new window]   Fig 2. Axial T1-weighted spin-echo image demonstrates marked displacement of the heart into the left hemithorax with the cardiac apex pointing posteriorly.

View larger version (144K): [in this window] [in a new window]   Fig 3. Axial T1-weighted spin-echo image demonstrates the left atrial appendage and the main pulmonary artery extending far beyond the mediastinal margins into the left lung. Because of the lack of left pericardium, a "tongue" of lung tissue interposes between the main pulmonary artery and aorta (arrow), our pathognomonic feature for congenital absence of pericardium.

View larger version (159K): [in this window] [in a new window]   Fig 4. Coronal T1-weighted spin-echo image demonstrates the lung extending below the heart, interposing between its inferior surface and the left diaphragm (asterisk).

	Results

Top Abstract Introduction Patients and methods Results Comment References

Other symptoms included dyspnea in 4 patients (3 exertional, 1 nocturnal) and a sensation of "shifting heart" in 2 patients.

Clinical examination showed marked displacement of the cardiac apex to the left (mid-to-posterior axillary line) in 7 patients; all of them had complete absence of left pericardium. In addition, 9 patients had a soft ejection systolic heart murmur, best heard at the left sternal border.

Diagnostic testing
CXRs were diagnostic in all but 1 patient (Table 2). The posteroanterior films of 9 patients were available for review and in 7 of them a characteristic marked displacement of the cardiac silhouette to the left, corresponding with displacement of the cardiac apex on palpation, was present (Fig 1); this levoshift resulted in loss of the right heart border through its superimposition on the spine in all 7 patients. Lung tissue interposing between the main pulmonary artery and the aorta was the most common radiographic feature, seen in 9 of the 10 patients.

Echocardiographic data were obtained in all patients. A lateral probe position for the apical four-chamber view was required in all but 1 patient. None of the patients had other coexisting congenital heart disease. Right ventricular dilation was seen in 4 patients, whereas paradoxical septal motion was present in 5 patients. Ventricular function was normal in all.

Three patients early in the series underwent cardiac catheterization to assist in the diagnosis; a protruding left atrial appendage through a partial pericardial defect established the diagnosis in 1 of them. In 6 patients, additional imaging with computed tomographic scan (3) and MRI (3) was obtained to confirm the suspected diagnosis of absent pericardium. Finally, 4 patients underwent selective coronary angiography while investigated for possible coronary artery disease. None of them had significant coronary artery stenoses.

Subsequent to testing, diagnoses were as follows: 7 patients had complete absence of the left pericardium including 1 patient with total absence of both right and left pericardia, whereas 3 patients had partial absence of the left pericardium including one patient with a foramen-type defect.

Surgical reconstruction
Four of the 10 patients underwent surgical reconstruction of absent pericardium at a median age of 19 years (range, 8 to 41 years). One additional patient has been referred for reconstructive surgery. The decision to recommend and proceed with the surgical procedure was made on the basis of symptoms: (1) debilitating symptoms in 3 patients with complete absence and (2) herniation of left atrial appendage (Fig 5) in 1 patient with partial absence of foramen type (Table 1). Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) material was used to reconstruct the absent left pericardium in 3 patients, whereas xenograft pericardium was employed to repair the partial left defect with atrial herniation in 1 patient. Running 4-0 Prolene (Ethicon, Somerville, NJ) was used to suture one or more large pieces of Gore-Tex membrane to the edges of the remnant of pericardium in an interlocking fashion. Care was taken not to injure the left phrenic nerve, coursing anteriorly to the free edge of the defect. After repositioning of the heart, the lateral and anterior surface of the newly reconstructed pericardium was sutured to the lateral and medial aspect of the diaphragmatic surface. Intraoperative transesophageal echocardiography was performed at the end of the procedure in the last 2 patients to ensure that there was no compromise to cardiac function. Cardiopulmonary bypass was required to mobilize the heart and reconstruct the pericardium in 2 patients (74 and 65 minutes).

View larger version (136K): [in this window] [in a new window]   Fig 5. Posteroanterior radiograph from an 8-year-old patient presenting with acute stabbing chest pain. Herniated left atrial appendage (arrow) is seen through a foramen-type partial absence of the left pericardium.

Follow-up
Contact was made with 9 of the 10 patients, all of whom agreed to participate in the study. Information from the Ontario Death Registry indicated that the 10th patient, in whom direct contact failed, was alive in 1998. Thus, all patients were alive at a mean of 10.5 years from presentation.

Clinical status
Patients were seen and assessed at the Toronto Hospital between June 1998 and February 1999; 1 patient was seen in another province for reasons of convenience. Interval change in the symptomatic status of the patients is shown in Table 3. All 4 surgical patients reported substantial decrease in the severity and frequency of pain experienced before operation, with complete resolution of symptoms in 2 of them. Symptoms remained largely unchanged in the patients who did not undergo operation. No patient developed new cardiac symptoms.

View larger version (154K): [in this window] [in a new window]   Fig 6. Postoperative (3 months) posteroanterior radiograph from the same patient as in Figure 1 demonstrating persisting levoposition of the heart. Note the development of intrapericardial fat, replacing the lung tissue previously interposing between the main pulmonary artery and aorta (arrow), compared with Figure 1.

MRI
Data are shown in Table 3. MRI clearly delineated the presence of normal pericardium as a thin (< 3 mm) line of uniform low-signal intensity separating the high-signal intensity fat within the epicardial fat layer posteriorly and the pericardial fat layer anteriorly (Fig 7). MRI confirmed the diagnosis and determined the extent of the defect (complete left and right, complete left and partial left). Lung interposing between the main pulmonary artery and aorta was seen in all 6 patients who had not undergone operation, establishing this marker as the pathognomonic feature of absent pericardium in our series. There was no evidence of herniation of cardiac chambers in any of the patients operated or not. Levoposition of the heart persisted in the 3 patients with complete pericardial absence who underwent pericardioplasty; however, the cardiac apex was pointing laterally and not posteriorly (Fig 7) as it did before the surgical procedure (Fig 2). Of interest, the left lower pulmonary vein was compressed between the left atrium and descending aorta/spine (Fig 8), secondary to the levoposition and posterior rotation of the heart in 3 patients; 2 of them complained of exertional dyspnea. There was no evidence of significant obstruction at rest, however.

View larger version (131K): [in this window] [in a new window]   Fig 7. Axial T1-weighted spin-echo image showing postsurgical reconstruction of the pericardium and resuspension of the heart. (Preoperative magnetic resonance image from the same patient is shown in Figure 2.) Although the majority of the heart is still in the left hemithorax, the cardiac apex now points laterally not posteriorly. Note also the development of extrapericardial fat (arrow) after pericardioplasty with Gore-Tex membrane in this patient with previous complete absence of left pericardium.

View larger version (109K): [in this window] [in a new window]   Fig 8. Axial T1-weighted spin-echo image showing close approximation and mild compression of the left lower pulmonary vein (arrow) by the descending aorta. However, there was no significant stenosis detected by Doppler.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

CAP has been discovered inadvertently during postmortem and thoracotomy for more than 400 years [1, 2]. Isolated and symptomatic absent pericardium has only been described, however, in single case reports [7–11]. The reason for this has to be the rarity of the condition. It is impossible to ascertain its total prevalence, although the isolated form of this lesion comprises only a portion of the 0.0001% to 0.044% surgical/pathologic prevalence of absent pericardium described by various authors [3, 4]. As many as one third of all cases of CAP described today were in association with other cardiac lesions, such as patent arterial duct, mitral stenosis, tetralogy of Fallot, and others [9, 10].

All but 1 of our patients presented with a characteristic periodic stabbing chest pain, largely nonexertional, which often could be induced or relieved by postural changes. Although not typical for angina, this presentation with chest pain may instigate investigations for coronary artery disease, as indeed happened in 4 of our patients. The cause of pain in CAP remains unclear. All but 1 patient in our cohort experienced chest pain, regardless of the type of pericardial defect, ranging from partial to total absence of the pericardium, suggesting that the cause of pain may be multifactorial. Herniation of the left atrial appendage through a foramen type of defect has been described previously [11–14] and was the case in 1 of our patients. Torsion of the great vessels secondary to increased heart mobility, lack of pericardial cushioning, tension on pleuropericardial adhesions, and pressure on the pericardial rim [1] all have been postulated as possible causes of pain. Furthermore, ischemia during thallium scanning [15] was demonstrated in a case report of a patient presenting with angina-like pain. Constriction of the coronary arteries by fibrous bands on the lower edge of the absent pericardium [16, 17] was thought to be another possible pathogenic mechanism. Improvement or resolution of chest pain in this study after surgical reconstruction, which in turn results in immobilization of the heart, would suggest that the pain is related to heart mobility. The absence of coronary artery stenoses at rest in the 4 patients from this series who underwent selective coronary angiography would also support this hypothesis.

Different ways of establishing the diagnosis of CAP have been proposed. All patients with complete absence of pericardium from this series had marked lateral displacement of the cardiac apex on palpation. This clinical feature combined with a history of atypical chest pain should alert clinicians of a possible diagnosis of CAP. The diagnosis often could be confirmed by chest radiography [18]. Echocardiography was necessary to exclude other cardiac disease. Lateral acoustic windows were frequently required, strongly suggestive of CAP [19]. Of note, right ventricular dilation and paradoxical motion were not present after pericardioplasty, indicating that lateral and posterior rotation of the heart may be responsible [20]. MRI established the diagnosis in all cases, determined the extent of the defect, and excluded herniation of cardiac structures. A "tongue" of lung tissue interposing between the main pulmonary artery and aorta was the most consistent diagnostic feature in our series, both radiographically and at MRI, encompassing patients with partial and complete absence of pericardium alike.

Surgical procedures employed for patients with CAP include left atrial appendectomy, division of adhesions, pericardiectomy, extension of the defect, or pericardioplasty. In our intention to treat approach, for patients with debilitating symptoms we employed pericardioplasty. Our hypothesis was that immobilization of the heart with pericardial reconstruction will lead to symptomatic improvement. Despite the small number of patients, we have been encouraged by the results. Elective pericardioplasty for severely symptomatic patients from this series was safe, the associated morbidity was acceptable, and there was marked symptomatic improvement in all. Previous reports argued that diagnosis of moderate-sized pericardial defects in symptomatic or nonsymptomatic patients should be followed by prophylactic operation to reduce the risk of death from cardiac structure herniation and incarceration [21, 22]. Thus, partial absence of the pericardium has always been of greatest concern in the literature [1, 9, 23]. In our series of patients with isolated CAP, however, the focus was not on prophylactic management but rather on the management of symptoms.

Limitations
This is not a natural/unnatural history study. Patients’ enrollment was based on previous attendance at the UTCCCA, Toronto Hospital and The Hospital for Sick Children, Toronto. Data regarding the denominator, ie, the total population of CAP, are lacking. Selection criteria for surgical intervention were determined clinically and based on the intention to treat severely symptomatic patients. The absence of a comparable medical group limits the ability of the study to address whether pericardioplasty should be performed in all patients with complete absence of pericardium and debilitating symptoms. Nevertheless, we believe our clinical series to be representative of patients with CAP.

Conclusions
We conclude that isolated CAP has a common presentation pattern with periodic stabbing chest pain that may mimic coronary artery disease. Chest radiography and MRI are required for definitive diagnosis. Patients with the complete form of the defect may present with debilitating symptoms. Elective pericardioplasty is safe and may offer these patients symptomatic relief.

	Acknowledgments

 
We thank our colleagues from The Hospital for Sick Children, Toronto, for their continuing support of our program. We acknowledge Dr Catherine Kells and Dr Jonathan Howlett for assisting us with follow-up data.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Glen S. Van Arsdell Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gatzoulis, M. A. Articles by Webb, G. D. Search for Related Content PubMed PubMed Citation Articles by Gatzoulis, M. A. Articles by Webb, G. D.