P172 AN ACCESSORY PATHWAY WITHOUT REENTRANT TACHYCARDIA

A 65–year–old patient, hypertensive, dyslipidemic, strong smoker. He has heart disease with hypokinetic evolution EF 47%, mild MI. Negative Dipyridamole–stress echocardiography dated January 2008. Recently atrial fibrillation (AF) is found and anticoagulant therapy was started. Dyspnea and weight loss occurred in past two months. Detected keratinizing squamous pulmonary Ca with negative markers. This injury was judged to be inoperable, and the patient get indications for chemotherapy and radiotherapy. The patient also starts complaining of dyspnea and chest pain on exertion: Not serological modification, not ischemic ECG. Echocardiogram LVEF 47–50% highlights diffuse hypokinesia, regular valves. Ergometric test was not evaluable for ischemia. Coronary angiography shows stenosis of proximal and middle anterior interventricular coronary and non–critical lesions of circumflex and right coronary. Ecodobutamine test was positive for ischemia and arrhythmias (AF and wide QRS tachycardias in recovery phase), but negative for angor. The patient was treated with CT and IVA I – II. angioplasty Monitoring shows AF with high penetrance, wide QRS tachycardia runs and very short TVNS. ECG 1: During atrial tachycardia, show broad QRS conduction to BBSX alternating with narrow QRS with the same RR interval. ECG 2. show fusion between the wavefront conducted with narrow QRS and that with wide QRS. These are supraventricular arrhythmias that run along the atrioventricular nodal pathway (NAV) in the narrow QRS tracts and take an accessory pathway in the wide QRS run.The Mahaim fibers have decremental conductivities like the AV node, therefore high ventricular frequencies does not occur AF appeared during ecodobutamine, but some beats were conducted by an anomalous path in a discontinuous way); they are generally directed from the atrium or the NAV, towards another part of the right ventricular conduction system, with atrium wave or NAV – RB, therefore the early activation of the RB generates a widened QRS, with a LBB morphology. ECG 3 Re–entry on Mahaim pathway, ventricular activation widened through Mahaim fiber, which generate LBB morphology with retrograde atrial depolarization. In this case there is no reentry, but we have an atrial tachycardia conducted alternately on an accessory pathway and across the NAV. Given the patient‘s clinical problems and the total absence of symptoms, the patient remains asymptomatic during therapy with amiodarone and beta–blocker.