A Case Report of Left Atrial Rhythm in Mirror Image Dextrocardia

A girl of thirteen years was admitted to Iwate Medical University Hospital on December 22th, 1956, complaining of palpitation by physical exertion since childhood. She had a splendid physique and was well-nourished, and didn't have any acquired diseases at that time. But her heart had a shape of dextrocardia on chest x-ray film, and it had been recognized on physical and x-ray examinations that she had heterotaxia of abdominal organon. Marked systolic murmur was heard on the right sternal line in the IIIrd intercostal space. The right and left heart catheterization had revealed VSD and ASD. The right and left heart catheterization and the cineangiocardiography suggested strongly mirror image dextrocardia. Nevertheless in ECG, P waves in I, aVL and left precordial leads were positive with a P-R interval of 0.19 second, and P waves in aVR, V4R, V5R, and V6R were negative. So they didn't coincide with the ordinary ECG-criteria of mirror image dextrocardia. But mirror image dextrocardia, as well as VSD and foramen ovale, were made sure by operation. Namely the P wave pattern above mentioned was proved to represent left atrial rhythm. Also "dome and dart" type P waves were seen m V2. So this left atrial rhythm was fit for the lst type, according to the classification of M. MIRROWSKI. After operation, pacemaker wandering between sinus node and left atrium was seen without artificial procedures. In sinus rhythm, P waves in I, aVL and left precodial leads were negative with a P-R interval of 0.20 second and P waves in aVR, V4R, V5R and V6R were positive. Compression on eyeballs or carotid sinus failed to change the position of pacemaker. But posture change from supine to erect position converted left atrial rhythm to sinus rhythm.