A 39-year-old woman was referred for investigation of a heart murmur heard on routine medical examination. Our evaluation revealed a right-sided heart with mirror imaged atrial arrangement, a defect in the oval fossa with a mean diameter of 16 millimetres, moderate enlargement of the right-sided cardiac chambers, mild pulmonary hypertension, and a ratio of pulmonary-to-systemic flows exceeding 2.3 to 1. The patient agreed to percutaneous insertion of a device to achieve closure.

Intracardiac echocardiography (Fig. 1) using mechanical equipment (UltraICE, Boston Scientific Corp.) proved surprisingly easy to interpret, keeping in mind the mirror-imaged atrial arrangement. The morphologically right atrium was seen at the top of the screen, with its appendage (RAA) pointing leftward rather than to the right, while the ascending aorta (AO) lay on the left of the screen, and to the left of the left atrium (LA) rather than to the right. To obtain a 4-chamber view for measurement of one diameter of the defect, and to monitor the implantation, we rotated the intracardiac echocardiographic catheter posteriorly and to the right, rather than to the left (Fig. 2). This position clearly visualized the morphologically left (LA) and right (RA) atriums, the mitral valve (MV), and the tricuspid valve (TV). Diameters of the defect in the aortic valvar and four-chamber planes were measured as previously described,Reference Rigatelli and Hijazi¹ and found to be 21 millimetres and 18.2 millimetres, respectively. The antero-inferior and postero-superior rims were both of more than 3.5 millimetres, and were deemed adequate to anchor the device. Based upon these measurements, we implanted a 22 millimetre Amplatzer atrial septal defect Occluder (AGA Medical Corp.). The chest radiograph in

shows the intracardiac echocardiographic catheter (ICE) and the Amplatzer septal occluder (aso), and intracardiac echocardiography (Fig. 4) confirmed a good result. Follow-up transthoracic echocardiography 12 hours later, prior to discharge, and transoesophageal studies after one month, also showed a completely stable device, without any residual intracardiac shunt.

Figure 1

Figure 2

Figure 3

Figure 4

While percutaneous closure of a defect in the oval fossa has been successfully performed previously in a right-sided heart, this is the first case, to our knowledge, in which intracardiac echocardiography was used to guide the procedure in a patient with mirror imaged atrial arrangement.