General Procedures Prior to ablation, blood will be drawn for measuring c-reactive protein, brain natriuretic polypeptide, D-dimer and prothrombin fragment 1.2. A transesopahegeal echocardiogram and an intracardiac echocardiogram will be performed. Then following sterile techniques, standard catheters will be passed through veins and positioned into the heart using X-ray guidance, and will cross the wall that divides the upper chambers of the heart so that the left atrium can be reached.The catheters will be used to trigger sites that originate the anomalous rhythm and once these are identified the generator will deliver radiofrequency energy to destroy the areas that cause irregular beats. After ablation follow-up visits will be done at one, three, six and twelve months. During that time several tests such as electrocardiograms, 24 hour Holter recording, computed tomography of the heart, transesophageal echocardiogram and repeated blood drawing to measure c-reactive protein, brain natriuretic peptide, D-dimer and prothrombin fragment 1.2 will be done.