Asian Cardiovasc Thorac Ann 1999;7:142-143
© 1999 Asia Publishing EXchange Pte Ltd
Intussusception of Left Atrial Appendage Through the Mitral Valve
Sanjay B Dhaded, MCh,
Hemant P Pathare, MCh,
Sanjay Ghotkar, MS,
Jagdish Khandeparkar, MCh,
Ratna A Magotra, MS,
Jaya Deshpande, MD,1,
Ammu Sivaraman, MD,1,
Pradeep Vaideeswar, MD,1
Department of Cardiothoracic Surgery
1 Department of Cardiothoracic Pathology
King Edward VII Memorial Hospital
Mumbai, India
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For reprint information contact: Sanjay B Dhaded, MCh Tel: 91 22 611 3358 Fax: 91 22 611 5958 email: analyst{at}bom3.vsnl.net.in Department of Cardiothoracic Surgery, King Edward VII Memorial Hospital, Mumbai 400012, India.
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Abstract
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A 4-month-old male infant underwent elective repair of a large subaortic ventricular septal defect. Although it was an uneventful surgical procedure, he required inotropic support during weaning from cardiopulmonary bypass. He presented with sudden-onset low cardiac output syndrome in the immediate postoperative period and could not be revived. Autopsy revealed intussusception of the left atrial appendage projecting through the mitral valve orifice.
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Introduction
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Intussusception of the left atrial appendage through the mitral valve is an extremely rare cause of low cardiac output syndrome in the immediate postoperative period. Unfortunately, when it occurs in the recovery room, not only is it unsuspected but the suddenness of its occurrence usually precludes any salvage.
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Case Report
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A 4-month-old male infant presented with failure to thrive, recurrent lower respiratory tract infection, and excessive precordial activity of 2 months duration. He had been referred to a local primary health care center where a diagnosis of ventricular septal defect was made. Physical examination revealed a non-cyanosed malnourished cachectic infant weighing 3.5 kg (birth weight, 2.5 kg) with a regular heart rate of 144 beats•min–1 and blood pressure of 90/60 mm Hg. Precordial activity was prominent with a normal first heart sound and loud pulmonic second sound. There was a holosystolic murmur grade 3/6 located at the lower left sternal margin and a soft diastolic murmur at the apex. His electrocardiogram showed sinus rhythm, QRS axis of 110°, prominent P wave, and left ventricular strain pattern. Chest radiography demonstrated cardiomegaly (cardiothoracic index, 0.6), a prominent pulmonary artery segment, and plethoric lung fields. Doppler echocardiography confirmed a non-restrictive subaortic ventricular septal defect with severe pulmonary hypertension. The interatrial septum was intact and the systemic and pulmonary veins drained normally. Blood investigations revealed a hemoglobin level of 166 g•L–1 and a prothrombin time of 18/13 sec.
The subaortic ventricular septal defect was repaired with a Dacron patch via a transatrial approach using hypothermic cardiopulmonary bypass with cold crystalloid cardioplegic arrest and topical cooling. Temporary right ventricular epicardial pacing wires were inserted and the patient was weaned off bypass with dopamine and isoprenaline support. One hour later in the recovery unit, he developed sudden onset multifocal ventricular ectopic beats and low cardiac output syndrome. The serum potassium levels were within normal limits. The right atrial pressure was minimally raised. The child could not be salvaged.
Autopsy revealed intussusception of the left atrial appendage. The left atrial cavity was occupied by the inverted appendage (Figure 1
), covered by the discolored endocardium. It rested upon the anterior mitral leaflet and projected into the mitral valve orifice.
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Figure 1. Opened left atrium showing intussusception of the left atrial appendage through the mitral valve orifice, causing left ventricular inflow obstruction.
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Discussion
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After intracardiac repair of a ventricular septal defect, persistent low cardiac output syndrome can be caused by inadequate myocardial preservation, iatrogenic atrioventricular valve incompetence, residual or additional intracardiac defect, hypothermia, conduction disturbances, coronary air embolism, persistent pulmonary hypertension, or reperfusion injury. Intussusception of the left atrial appendage through the mitral valve orifice has not been reported as a cause of low cardiac output syndrome in the immediate postoperative period. Unfortunately, when it occurs in the recovery room, not only is it unsuspected but the suddenness of its occurrence usually precludes salvage. In fact, it may not be obvious even during open cardiac resuscitation in the recovery unit, since it is not specifically looked for.
We speculate that vigorous de-airing procedures such as suction applied to the aortic root in our case (or the left ventricular vent introduced via the right superior pulmonary vein in an adult patient) just prior to release of the aortic cross-clamp, might lead to excessive negative pressure within the left ventricle with partial intussusception of the left atrial appendage into the left atrial cavity. This may have initiated a vicious cycle inducing progressively more intussusception, culminating in acute acquired mitral valve obstruction and sudden death. Shorter appendages with a wide base are more likely to become inverted.1
We feel that the practice of routinely inverting the left atrial appendage to de-air the left atrium completely, which is commonly carried out in adult cardiac surgery should not be carried out in infants. Allen and colleagues1 have reported left atrial appendage inversion diagnosed intraoperatively on transesophageal echocardiography in an adult patient undergoing mitral valve repair and postoperatively in a case of tetralogy of Fallot but there was no left ventricular inflow obstruction in either case. As our case aptly illustrates, we differ from their viewpoint that left atrial appendage inversion can be ignored if diagnosed on echocardiography, since it usually gets better with time.
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Acknowledgments
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We would like to thank Pradnya Pai, MD, Dean, King Edward VII Memorial Hospital, Mumbai for allowing us to use hospital data in this publication.
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Reference
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Allen BS, Ilbawi M, Hartz RS, Kumar S, Theole D. Inverted left atrial appendage: an unrecognized cause of left atrial mass. J Thorac Cardiovasc Surg 1997;114:278–80.[Free Full Text]
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Abstract
Introduction
