Adenosine to Assess Complete Conduction Block During Catheter Ablation of Paroxysmal Atrial Fibrillation

Inclusion Criteria: 1. Patients \>18 and \<75 who are able to give informed consent undergoing atrial fibrillation ablation procedure. 2. Paroxysmal Atrial fibrillation lasting = 7 days which is self-terminating. It is considered recurrent if two or more episodes occur. 3. Failure or unwilling to take class I or III anti-arrhythmic drugs Exclusion Criteria: 1. History of asthma 2. Patients with severe coronary artery disease, stable/unstable angina, or ongoing myocardial ischemia 3. Previous cardiac surgery ( excluding CABG and mitral valve surgery) 4. Symptomatic congestive heart failure including but not limited to NYHA III/IV and/or documented ejection fraction \<40% measured by acceptable cardiac testing, 5. Left atrial diameter \>55mm 6. Moderate to severe mitral or aortic valve disease 7. Myocardial infarction within three months of enrollment 8. Congenital heart disease where it increases the risk of an ablative procedure 9. Prior ASD/PFO closure with a device using a percutaneous approach 10. Hypertrophic cardiomyopathy (LV wall thickness \>1.5mm) 11. Pulmonary Hypertension (mean or systolic PA pressure\> 50mmHg on Doppler echocardiography 12. Any prior ablation of atrial fibrillation 13. Enrollment in any other arrhythmia protocol 14. Any ventricular arrhythmia being treated where the arrhythmia or management may interfere with this study 15. Active infection or sepsis 16. Any history of cerebrovascular disease including stroke or TIAs 17. Pregnancy or lactation 18. Left atrial thrombus at the time of ablation 19. Untreatable allergy to contrast media 20. Any diagnosis of atrial fibrillation secondary to electrolyte disturbance, thyroid disease, or any other reversible or non-cardiovascular causes 21. History of blood clotting(bleeding or thrombotic) abnormalities 22. Known sensitivities to heparin or warfarin 23. Severe COPD (defined as FEV1 \<1) 24. Severe comorbidity or poor general physical/mental health that, in opinion of the investigator, will not allow the patient to be a good study candidate (i.e. other disease processes, mental capacity, substance abuse, shortened life expectancy)