Discussion

Left atrial appendage inversion is a rare complication following cardiac surgery. ^{Reference Allen, Ilbawi and Hartz1} This occurs due to the negative pressure created by the left atrial vent during surgery or during deairing procedures. ^{Reference Cohen, Tamir and Yanai2,Reference Fujiwara, Naito and Noguchi3} There have been reports of left atrial appendage inversion in pericardial effusion, which could be due to the increased intrapericardial pressure. ^{Reference Gecmen, Candan and Guler4} Spontaneous inversion of the left atrial appendage in the absence of above two situations is also reported. ^{Reference Powell, Taylor and Cottrill5} If it is recognised during surgery in the post-operative transoesophageal echocardiogram, it may be corrected by digital manipulation. However, if it is recognised later, no intervention is required as spontaneous resolution occurs. Occasionally, if it causes haemodynamic compromise by obstructing the left ventricular inflow, intervention may be required. ^{Reference Molaei, Tabib and Meraji6}

In both our patients, transoesophageal echocardiogram was not performed intraoperatively as the weight of the infants was less than 5 kg. Thus, it went unnoticed in the immediate post-operative period. In both, left atrial vent was placed through the patent foramen ovale during surgery. The negative pressure caused by the vent was probably responsible for the inversion of the left atrial appendage. Thus, the appearance of a tubular mass protruding towards the mitral orifice with the absence of flow into it and having the same echodensity as the atrial wall is suggestive of left atrial appendage inversion. Though the lesion has a misleading appearance of a mass on the four-chamber and parasternal long-axis views; the subcostal views are diagnostic and clearly demonstrate the inversion of the appendage. Hence, we suggest a detailed subcostal echocardiographic examination when there is a new appearance of a left atrial mass following cardiac surgery. Cardiologists should be aware of this condition as recognition of this entity will avoid unnecessary investigations and unindicated treatment with anticoagulants.