Abstract
A 79-year-old female presented to our hospital with a history of experiencing palpitations occasionally from the age of around 20, which suddenly worsened when she became 78-years-old. She developed dyspnea and was hospitalized with acute heart failure. Monitoring during hospitalization revealed incessant wide-QRS tachycardia, and echocardiography revealed low ejection fraction, which suggested tachycardia-induced cardiomyopathy. A cardiac electrophysiologic study was performed, and a left accessory pathway was diagnosed to be present, because impulses along the accessory pathway arrived earliest at the left-sided wall in both the anterograde and retrograde conductions. Wide-QRS tachycardia was easily induced by extra stimulation from the high right atrium and right ventricle. The tachycardia was diagnosed as antidromic AVRT (atrioventricular reciprocating tachycardia), in which impulses are conducted in the anterograde direction through the accessory pathway and in the retrograde direction through the slow pathway, because : 1) the QRS waveform was similar to that seen during normal sinus rhythm ; 2) the site of earliest activation in the ventricular wall was CS1-2 ; and 3) Retrograde conduction was long and the earliest site of atrial activation was the coronary sinus ostium. Furthermore, orthodromic AVRT, in which the conduction is anterograde over the atrioventricular node and antidromic over the accessory pathway, was also induced by premature ventricular contractions, which developed accidentally. Ablation was performed, and after the accessory pathway had been blocked. Improvement in cardiac function was observed after correcting the WPW syndrome.
