Ann Thorac Surg 2011;92:1522-1524. doi:10.1016/j.athoracsur.2011.04.038
© 2011 The Society of Thoracic Surgeons
Case Reports
Atrial Septal Dissection Late After Congenital Heart Surgery
Kenneth R. Knecht, MDa,*,
Michiaki Imamura, MD, PhDb
a Division of Pediatric Cardiology, Arkansas Children's Hospital and University of Arkansas for Medical Sciences, Little Rock, Arkansas
b Division of Cardiothoracic Surgery, Arkansas Children's Hospital, and University of Arkansas for Medical Sciences, Little Rock, Arkansas
Accepted for publication April 5, 2011.
* Address correspondence to Dr Knecht, Division of Pediatric Cardiology, Arkansas Children's Hospital and University of Arkansas for Medical Sciences, 1 Children's Way, Slot 512-3, Little Rock, AR 72022-3591 (Email: krknecht{at}uams.edu).
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Abstract
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Atrial septal dissection is a rare entity usually seen after surgical mitral valve repair, myocardial infarction, or endocarditis. This is a report of an atrial dissection in a young girl found on routine follow-up echocardiography after repair of atrial and ventricular septal defects. No identifiable predisposing risk was found prior to or at the time of surgical repair. Considerable risk of significant morbidity and even mortality attends atrial dissection due to the risk of rupture.
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Introduction
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Atrial septal dissection occurs when the interatrial septum separates creating a new pocket, distinct from the true atria [1]. It is a rare occurrence and when it is found it usually occurs after an insult to the endocardium. These insults include mitral valve surgery, endocarditis, or myocardial infarction with dissection usually noted soon after the precipitating event.
A 5-year-old Caucasian girl with a history of Down syndrome had undergone a suture closure of a secundum atrial septal defect and patch closure of a perimembranous ventricular septal defect at 5 months of age. At the time of this surgery the left atrium was vented through the atrial septal defect. The base of the anterior and septal leaflet of the tricuspid valve was partially detached to expose the defect and it was re-sutured after closure of the defect. The patient's operative and hospital course were uncomplicated. Her postoperative follow-up was uneventful from a cardiovascular standpoint. The patient's past medical history was otherwise significant for developmental delay coincident to her genetic syndrome, medically managed hypothyroidism, and treatment with a fiber supplement for constipation. She took no other medications and had required no other surgeries or interventions other than outpatient developmental therapies for any reason. There was no history of unexplained fever, no new neurologic deficits, and no growth failure. She presented to the cardiology clinic for routine follow-up. A transthoracic echocardiogram demonstrated an apparent pocket within the atrial septum, which filled during ventricular systole and collapsed during ventricular diastole (Fig 1). By Doppler interrogation there was no obstruction to flow through either the atrioventricular valve or inter-atrial shunting; there was mild tricuspid regurgitation, but no mitral insufficiency.
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Fig 1. Transthoracic echocardiogram four-chamber view (A) in systole and (B) diastole. (A) The arrow indicates the space within the atrial septum created by the dissection during ventricular systole. This space collapses completely during ventricular diastole.
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Further imaging with transesophageal echocardiography demonstrated an aneurysm of the atrial septum with the orifice originating from the left ventricular outflow tract anterior to the anterior mitral leaflet and inferior to the noncoronary cusp of the aortic valve (Fig 2). This dissection divided the atrial septum into two layers. Filling was from the left ventricle during ventricular systole with the defect completely collapsing during atrial systole. There was no residual shunting at the atrial or ventricular level.
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Fig 2. Transesophageal echocardiographic image with probe posterior to the left atrium. (A) Arrow indicates position of the dissection medial to the anterior mitral valve leaflet. (B) The orifice arises from the left ventricular outflow tract and was anterior to the noncoronary cusp of the aortic valve (not seen in this plane). Asterisk (*) = anterior mitral leaflet; LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle.
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Due to the risk of rupture of the atrial septal dissection, the patient was taken to the operating room for dissection repair. Regular bicaval cannulation and antegrade cardioplegic cardiac arrest was instituted. The previous right atriotomy was opened, as was the line of atrial defect closure for venting. A bulge within the atrial septum was seen anterior to the previous atrial septal defect closure suture line. This bulging atrial septum was longitudinally opened in the length of 1.5 cm. The dissection was completely separate from the previous atrial septal closure suture line. Within this bulging space, the opening of the atrial septal aneurysm orifice to the left ventricle was identified. The size of the orifice was 8 to 10 mm, and this orifice was covered with fibrous tissue. Because it was difficult to close using a single round patch, the orifice was closed using two 20-mm half-moon shaped bovine pericardial patches sewn on and then together with a running suture technique. The dissected space was imbricated with mattress sutures. At the time of surgical closure, the endocardium and remainder of the heart showed no evidence of previous endocarditis or other insult beyond that in her cardiac surgical history.
Postoperative transesophageal echocardiography and follow-up echocardiography 3 months after the reoperation showed complete occlusion of the dissecting space without recurrence.
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Comment
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This case report describes the occurrence of an unexpected atrial septal dissection in a young child. Her surgery was remote, both in location and time. Cardiac surgery had occurred more than 4 years in the past, and at an intracardiac location distinct from the dissection orifice. This entity is little known in pediatric cardiology, but its occurrence and complications can have major physiologic consequences. Although it is unlikely to become a common occurrence, this anomaly may be encountered more frequently in this era of congenital heart surgery and with increasing use of noninvasive imaging.
Dissection of the atrial septum has been defined as a new chamber within the inter-atrial septum originating from a gap between the mitral or tricuspid annulus and the inter-atrial septum with or without communication to the true left or right atrium [1]. This lesion has been reported after surgical intervention on the mitral and aortic valve, acute myocardial infarction, rheumatic heart disease, and endocarditis [1]. This complication is rare, occurring in an estimated 0.84% of mitral valve surgeries [2]. The inter-atrial septum is a multilayered structure composed of two muscular layers that lie on either side of a layer of fat [3]. Separation may occur in multiple planes through the fat between the two muscular layers or between the atrial endocardium and myocardium [4]. If there is an attendant disruption of the atrial wall creating a communication with an atrium, heart failure may result from the hemodynamic consequences. Reported complications of this rupture include physiology similar to acute atrioventricular valve regurgitation [4], including compromised antegrade ventricular output and hemorrhage into the pericardial space [2].
This case is unique in the literature in that there could not be any defined acute or subacute predisposing insult to the myocardium. Although this is reported as a surgical complication of valve repair, as well as retrograde cardioplegia [5], the cause in this patient remains unclear. Although this patient had undergone patch closure of a ventricular defect, the defect was perimembranous in position, and well removed from the mitral valve and plane of this dissection. Closure of her atrial defect had been done with a primary suture of a patent foramen ovale, again in a position away from the cardiac crux. Cardioplegia was antegrade from the aortic root and bypass cannulation was of the superior and inferior vena cavae. It remains possible that the atrial septum was injured during the initial surgery; a left atrial vent was placed, and the anterior and septal leaflets of the tricuspid valve were detached and reattached. Left atrial pseudoaneurysm formation 6 months and 2 years after mitral valve replacement has been reported [6].
Awareness of this phenomenon in pediatric medicine is limited. We believe this has not been previously reported in a child. The importance of this condition arises from the possible complication of aneurysmal rupture. With the orifice arising from the left ventricle, the lumen is exposed to systemic systolic pressure. The wall of the dissection consists of a partial thickness of the atrial septum, and the thickness depends on which plane dissects. Exposure of this thin tissue to systemic systolic pressure risks rupture of the aneurysm wall.
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References
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- Gallego P, Oliver JM, González A, Domínguez FJ, Sanchez-Recalde A, Mesa JM. Left atrial dissection: pathogenesis, clinical course and transesophageal echocardiographic recognition J Am Soc Echocardiogr 2001;14:813-820.[Medline]
- Osawa H, Yoshii S, Hosaka S, Suzuki S, Abraham SJ, Tada Y. Left atrial dissection after aortic valve replacement J Thorac Cardiovasc Surg 2003;126:604-605.[Free Full Text]
- Filaire M, Nohra O, Sakka L, et al. Anatomical bases of the surgical dissection of the interatrial septum: a morphological and histological study Surg Radiol Anat 2008;30:369-373.[Medline]
- Heidt MC, Menon AK, Roth P, Mitrev Z, Akintürk HK, Vogt PR. Left atrial dissection after mitral operation mimicking severe mitral regurgitation J Thorac Cardiovasc Surg 2004;127:596-597.[Free Full Text]
- He GW. Rare complication of retrograde cardioplegia: inner-wall perforation of the right atrium Ann Thorac Surg 1997;63:539-541.[Abstract/Free Full Text]
- Idir M, Deville C, Roudaut R. Delayed left atrial wall dissection after mitral valve replacement Echocardiography 2000;17:259-261.[Medline]
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Abstract
Introduction
