Ann Thorac Surg 2006;81:352-354
© 2006 The Society of Thoracic Surgeons
Case report
Technical Considerations for Myocardial Revascularization in Congenital Bilateral Hypoplasia of the Pericardium
Michael S. Firstenberg, MD,
Chittoor B. Sai-Sudhakar, MBBS,
Subha V. Raman, MD,
Robert E. Michler, MD
*
Department of Cardiothoracic Surgery, Ohio State University, Columbus, Ohio
Accepted for publication August 23, 2004.
* Address correspondence to Dr Michler, Department of Cardiothoracic Surgery, North Doan Hall, 8th Floor, Ohio State University, Columbus, OH 43210 (Email: msf5{at}po.cwru.edu).
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Abstract
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Congenital hypoplasia of the pericardium is a rare clinical condition that is typically encountered as an incidental finding during routine thoracic imaging or cardiothoracic surgery. Chest pain symptoms, when they occur, are often initially attributed to coronary ischemic syndromes, but herniation of cardiac structures through the pericardial defect, ischemia from torsion of great vessels, or compression of pulmonary parenchyma through defects between the aortic and pulmonary arteries can occur. Careful attention to cannulation techniques, conduit length, and the aberrant course of the phrenic nerves, typically through pericardial fibrous bands, is critical to the successful conduct of cardiac surgery.
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Introduction
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Congenital hypoplasia of the pericardium is an extremely rare clinical condition that is typically an incidental finding during routine thoracic imaging or cardiothoracic surgery. The etiology of chest pain, initially attributed to coronary ischemia, is unclear, but indications for surgical reconstruction of the pericardium are herniation of cardiac structures through the pericardial defect, ischemia from torsion of great vessels, or compression of pulmonary parenchyma through defects between the aortic and pulmonary arteries [1]. However, patients with large defects may be asymptomatic from their congenital disease, but nevertheless symptomatic from underlying coronary artery disease. We present a rare case of coronary revascularization in the context of bilateral congenital hypoplasia of the pericardium and discuss the surgical implications.
A 68-year-old man presented with chest discomfort, and stress testing demonstrated exercise induced reversible anteroapical ischemia. Transthoracic echocardiography was limited by suboptimal windows secondary to severe displacement of the heart into the left side of the chest. Cardiac catheterization revealed normal cardiac chamber pressures but significant multivessel stenoses. Owing to severe abnormal cardiac position observed on echocardiography and angiography, a pericardial defect was suspected and prompted confirmatory magnetic resonance imaging (Fig 1). At surgery, a midline anterior hypoplastic pericardial band overlying the right side of the leftward rotated heart contained both phrenic nerves. There was clockwise rotation of the heart behind the fibrous band into the left chest that resulted in posterior and lateral distortion of the apex, the left atrial appendage, and the main pulmonary artery, and an abnormal orientation of the circumflex and left anterior descending vessels (Fig 2). This required extra conduit length for both the left internal mammary artery and both saphenous veins. In addition, there was severe anterior-rightward angulation of the inferior vena cava–right atrial junction necessitating careful angulated placement of a dual stage venous drainage cannula to assure adequate flows. No pulmonary or intracardiac abnormalities were encountered. A suction stabilization device was used to elevate the heart to facilitate operative exposure. His postoperative course was uneventful, and he was discharged on the fifth postoperative day.
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Fig 1. Gradient echo cardiac magnetic resonance image in the oblique axial plane demonstrating marked posterior rotation of the left ventricular (LV) apex (arrow), coincident with the spine.
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Fig 2. Intraoperative view demonstrating cardiac rotation and displacement into the left side of the chest with severe angulation of the superior vena cava and RA junction. Silk sutures provide support for the pericardial band that contains both phrenic nerves and is retracted to the right for cardiac exposure. (RCC = retrograde cardioplegia cannula.)
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Comment
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Embryologically, pericardial defects are complex and poorly understood but are believed to be secondary to failure of the mesodermal-derived pleuropericardial membranes to close during the fifth week of development. The size of the resulting foramen can explain the spectrum of clinical symptoms and findings. Small defects may result in ischemic symptoms from herniation of cardiac structures such as the left atrial appendage and can cause intermittent chest pain, or they may result in acute strangulation and even death [2]. Larger defects may be asymptomatic or resemble chronic right-sided heart failure as an adaptation to chronic displacement of the entire heart into a hemithorax and increased flow resistance through distorted great vessels [3, 4]. However, when this lesion is diagnosed, symptoms should not be solely attributed to the congenital defect. A thorough evaluation is indicated since pericardial defects are also associated with intracardiac shunts, valvular abnormalies (particularly aortic), and lung herniation through the aortopulmonary window [5]. While the mechanism of chest pain in these patients is often complex, the compressive or constrictive effects of rudimentary fibrous bands on coronary arteries has been speculated to be a cause of myocardial ischemia even in the absence of underlying atherosclerotic disease [6].
When surgery is indicated, several anatomical factors must be considered. The approach should be through a median sternotomy to provide optimal identification of displacement structures that otherwise may be inaccessible or misidentified if other approaches are attempted. Lateral and posterior displacement of cardiac structures and great vessels may require minor modifications in standard cannulation techniques and close attention to potential distortions in what may be otherwise normal anatomical orientation. More importantly, even in cases of extreme pericardial defects, there must exist a thin fibrous connective band through which the phrenic nerves travel [7]. As in this patient, these bands may be anterior to the heart, and inadvertent division of these bands may result in catastrophic postoperative pulmonary insufficiency from bilateral diaphragmatic paralysis. These factors are even more critical in the reoperative setting, necessitating a careful review of previous operative notes and imaging. With small defects, repair is often indicated at the time of revascularization to prevent herniation and further symptoms. Larger defects are typically well tolerated, and repair can be technically difficult due to the absence of a framework of tissue to support a synthetic patch. Reconstruction is neither required nor recommended for these large defects, as the heart typically has adapted to the distorted anatomy and corrective attempts may result in unstable flow patterns.
Finally, careful attention to conduit length is critical. Leftward posterior rotation of the heart significantly increases the distance from the aorta to all distal coronary sites. The angle of the left internal mammary artery to the left anterior descending coronary artery may create a "bowstring," which must be evaluated with the lung inflated to prevent anastamotic disruption.
In conclusion, congenital absence of the pericardium is associated with rotation and distortion of otherwise normal cardiac morphology. Although routine radiographs and electrocardiograms may be unremarkable, any preoperative studies that suggest abnormal cardiac displacement should raise the concern for a pericardial defect and prompt further imaging. Intraoperatively, careful attention to cannulation techniques, conduit length, and aberrant course of the phrenic nerves, typically through pericardium fibrous bands, is critical to the successful conduct of cardiac surgery.
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References
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- Gatzoulis MA, Munk MD, Merchant N, Van Arsdell GS, McCrindle BW, Webb GD. Isolated congenital absence of the percardiumclinical presentation, diagnosis, and management. Ann Thorac Surg 2000;69:1209-1215.[Abstract/Free Full Text]
- Faridah Y, Julsrud PR. Congenital absence of pericardium revisited Int J Cardiovasc Imag 2002;18:67-73.
- Fukuda N, Oki T, Iuchi A, et al. Pulmonary and systemic venous flow patterns assessed by transesophageal Doppler echocardiography in congenital absence of the pericardium Am J Cardio 1995;75:1286-1288.
- Payvandi MN, Kerber RE. Echocardiography in congenital and acquired absence of the pericardiumAn echocardiographic mimic of right ventricular volume overload. Circulation 1976;53:86-92.[Abstract/Free Full Text]
- Nasser WK. Congenital absence of the left pericardium Am J Cardiol 1970;26:470-475.
- Nguyen DQ, Wilson RF, Bolman RM, Park SJ. Congenital pericardial defect and concomitant coronary artery disease Ann Thorac Surg 2001;72:1371-1373.[Abstract/Free Full Text]
- Funken JC, d'Udekem AY, Noirhomme P. Congenital pericardial defect Cardiovasc Surg 2002;10:618-619.[Medline]
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Abstract
Introduction
