Superiorly Directed Atrial Ectopy From The Left Inferior Pulmonary Vein

P wave morphology is often useful in planning and prognosticating invasive electrophysiology testing with an aim at ablation. It is generally believed that atrial ectopy of a pulmonary vein site of origin will be inferiorly directed. We report the case of superiorly directed P waves originating from the left inferior pulmonary vein, likely the result of a prior pulmonary vein isolation procedure. As demonstrated by our case, standard algorithms to identify the site of origin of atrial ectopy should be used with caution in patients with prior ablative procedures.A 58-year-old female with a history of recurrent symptomatic paroxysmal atrial fibrillation refractory to antiarrhythmic medications (sotalol and propafenone) underwent segmental pulmonary vein isolation 3 years prior to presentation. She presented to the emergency department with recurrent palpitations. Telemetry monitoring demonstrated frequent symptomatic monomorphic atrial premature depolarizations and salvos of atrial tachycardia that would occasionally degenerate to atrial fibrillation (Fig. 1). The axis of the tachycardia P wave was markedly negative in the inferior leads (Fig. 2, Fig. 3). The decision was made to proceed with diagnostic electrophysiology testing. After a double transeptal puncture, all veins were interrogated with the circular mapping catheter and chronic reconnection was noted in both inferior veins. Possibly due to general anesthesia, the patient did not demonstrate any spontaneous arrhythmias. Nevertheless, pacemapping (at threshold) from the left inferior pulmonary vein demonstrated a superiorly directed P wave that matched the clinical arrhythmia (Fig. 2, Fig. 3). The vein was reisolated with a single lesion to the inferior anterior aspect of the vein. Likewise, the right inferior pulmonary vein was easily isolated. The patient was evaluated 3 months post ablation and she is no longer demonstrating atrial dysrrhythmias off antiarrhythmic pharmacotherapy therapy.Fig. 2Pacing the circular mapping catheter with local electrogram capture and exit delay out of the vein followed by distal-to-proximal coronary sinus activation.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. 3Surface P wave pacemap.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Electrocardiographic criteria for identifying the site of origin of focal atrial arrhythmias are useful in planning and counseling patients when anticipating electrophysiology testing with the goal of potential ablation. Many algorithms have been explored and validated [1Rajawat Y.S. Gerstenfeld E.P. Patel V.V. Dixit S. Callans D.J. Marchlinksi F.E. ECG criteria for localizing the pulmonary vein origin of spontaneous atrial premature complexes: validation using intracardiac recordings.PACE. 2004; 27: 182-188Crossref Scopus (23) Google Scholar, 2Kistler P.M. Roberts-Thompson K.C. Haqqani H.M. et al.P-wave morphology in focal atrial tachycardia development of an algorithm to predict the anatomic site of origin.JACC. 2006; 48: 1010-1017Abstract Full Text Full Text PDF PubMed Scopus (302) Google Scholar, 3Teh A.W. Kistler P.M. Kalman J.M. Using the 12-lead ECG to localize the origin of ventricular and atrial tachycardias: part 1. Focal atrial tachycardia.J Cardiovasc Electrophysiol. 2009; 20: 706-709Crossref PubMed Scopus (28) Google Scholar]. The pulmonary veins reside in the superior half of the left atrium. As a result, it is generally accepted that ectopy originating from these structures is primarily directed inferiorly [1Rajawat Y.S. Gerstenfeld E.P. Patel V.V. Dixit S. Callans D.J. Marchlinksi F.E. ECG criteria for localizing the pulmonary vein origin of spontaneous atrial premature complexes: validation using intracardiac recordings.PACE. 2004; 27: 182-188Crossref Scopus (23) Google Scholar, 2Kistler P.M. Roberts-Thompson K.C. Haqqani H.M. et al.P-wave morphology in focal atrial tachycardia development of an algorithm to predict the anatomic site of origin.JACC. 2006; 48: 1010-1017Abstract Full Text Full Text PDF PubMed Scopus (302) Google Scholar, 3Teh A.W. Kistler P.M. Kalman J.M. Using the 12-lead ECG to localize the origin of ventricular and atrial tachycardias: part 1. Focal atrial tachycardia.J Cardiovasc Electrophysiol. 2009; 20: 706-709Crossref PubMed Scopus (28) Google Scholar]. Differentiating superior from inferior pulmonary veins is often based on the degree of positivity and/or the P-wave amplitude ratio in leads II and III [[1]Rajawat Y.S. Gerstenfeld E.P. Patel V.V. Dixit S. Callans D.J. Marchlinksi F.E. ECG criteria for localizing the pulmonary vein origin of spontaneous atrial premature complexes: validation using intracardiac recordings.PACE. 2004; 27: 182-188Crossref Scopus (23) Google Scholar].In our case, the left inferior pulmonary vein was chronically reconnected at the infero-anterior aspect, albeit with exit delay. With the lasso deep in the vein we could capture the local pulmonary vein electrogram with latency and exit to the atrial myocardium generating a superiorly directed P wave. We believe that the area of exit was small as indicated by the fact that isolation was achieved with a single point lesion. The delay on the distal coronary sinus catheter argues against ligament of Marshall capture.Many reasons could explain our finding. It is plausible that the location of the left inferior pulmonary vein was inferior enough in the left atrium to generate a negative vector in the frontal plane. However, this could not be supported by fluoroscopy or the electro-anatomical map in our case as the inferior veins were located in the upper half of the left atrium. Alternatively, scarring in the superior left atrium is likely to have decreased the excitable mass of tissue superior to the exit site of the vein. This is also unlikely to be the sole explanation, however, as no additional ablation was performed other than on the ostia of the pulmonary veins. We believe that the morphology of the P wave was due to the obligatory exit of electrical conduction to the anterior-inferior aspect of the vein. Whether the typically inferiorly directed P wave originating from the unablated inferior veins is a result of preferential exit in the superior aspect of the vein is not known.Ablation at the ostia of pulmonary veins may change the typical exit of electrical conduction originating from those structures and therefore limits the application of previously validated algorithms to predict the site of origin for atrial ectopy. These data should be used with caution when counseling such patients. P wave morphology is often useful in planning and prognosticating invasive electrophysiology testing with an aim at ablation. It is generally believed that atrial ectopy of a pulmonary vein site of origin will be inferiorly directed. We report the case of superiorly directed P waves originating from the left inferior pulmonary vein, likely the result of a prior pulmonary vein isolation procedure. As demonstrated by our case, standard algorithms to identify the site of origin of atrial ectopy should be used with caution in patients with prior ablative procedures. A 58-year-old female with a history of recurrent symptomatic paroxysmal atrial fibrillation refractory to antiarrhythmic medications (sotalol and propafenone) underwent segmental pulmonary vein isolation 3 years prior to presentation. She presented to the emergency department with recurrent palpitations. Telemetry monitoring demonstrated frequent symptomatic monomorphic atrial premature depolarizations and salvos of atrial tachycardia that would occasionally degenerate to atrial fibrillation (Fig. 1). The axis of the tachycardia P wave was markedly negative in the inferior leads (Fig. 2, Fig. 3). The decision was made to proceed with diagnostic electrophysiology testing. After a double transeptal puncture, all veins were interrogated with the circular mapping catheter and chronic reconnection was noted in both inferior veins. Possibly due to general anesthesia, the patient did not demonstrate any spontaneous arrhythmias. Nevertheless, pacemapping (at threshold) from the left inferior pulmonary vein demonstrated a superiorly directed P wave that matched the clinical arrhythmia (Fig. 2, Fig. 3). The vein was reisolated with a single lesion to the inferior anterior aspect of the vein. Likewise, the right inferior pulmonary vein was easily isolated. The patient was evaluated 3 months post ablation and she is no longer demonstrating atrial dysrrhythmias off antiarrhythmic pharmacotherapy therapy. Electrocardiographic criteria for identifying the site of origin of focal atrial arrhythmias are useful in planning and counseling patients when anticipating electrophysiology testing with the goal of potential ablation. Many algorithms have been explored and validated [1Rajawat Y.S. Gerstenfeld E.P. Patel V.V. Dixit S. Callans D.J. Marchlinksi F.E. ECG criteria for localizing the pulmonary vein origin of spontaneous atrial premature complexes: validation using intracardiac recordings.PACE. 2004; 27: 182-188Crossref Scopus (23) Google Scholar, 2Kistler P.M. Roberts-Thompson K.C. Haqqani H.M. et al.P-wave morphology in focal atrial tachycardia development of an algorithm to predict the anatomic site of origin.JACC. 2006; 48: 1010-1017Abstract Full Text Full Text PDF PubMed Scopus (302) Google Scholar, 3Teh A.W. Kistler P.M. Kalman J.M. Using the 12-lead ECG to localize the origin of ventricular and atrial tachycardias: part 1. Focal atrial tachycardia.J Cardiovasc Electrophysiol. 2009; 20: 706-709Crossref PubMed Scopus (28) Google Scholar]. The pulmonary veins reside in the superior half of the left atrium. As a result, it is generally accepted that ectopy originating from these structures is primarily directed inferiorly [1Rajawat Y.S. Gerstenfeld E.P. Patel V.V. Dixit S. Callans D.J. Marchlinksi F.E. ECG criteria for localizing the pulmonary vein origin of spontaneous atrial premature complexes: validation using intracardiac recordings.PACE. 2004; 27: 182-188Crossref Scopus (23) Google Scholar, 2Kistler P.M. Roberts-Thompson K.C. Haqqani H.M. et al.P-wave morphology in focal atrial tachycardia development of an algorithm to predict the anatomic site of origin.JACC. 2006; 48: 1010-1017Abstract Full Text Full Text PDF PubMed Scopus (302) Google Scholar, 3Teh A.W. Kistler P.M. Kalman J.M. Using the 12-lead ECG to localize the origin of ventricular and atrial tachycardias: part 1. Focal atrial tachycardia.J Cardiovasc Electrophysiol. 2009; 20: 706-709Crossref PubMed Scopus (28) Google Scholar]. Differentiating superior from inferior pulmonary veins is often based on the degree of positivity and/or the P-wave amplitude ratio in leads II and III [[1]Rajawat Y.S. Gerstenfeld E.P. Patel V.V. Dixit S. Callans D.J. Marchlinksi F.E. ECG criteria for localizing the pulmonary vein origin of spontaneous atrial premature complexes: validation using intracardiac recordings.PACE. 2004; 27: 182-188Crossref Scopus (23) Google Scholar]. In our case, the left inferior pulmonary vein was chronically reconnected at the infero-anterior aspect, albeit with exit delay. With the lasso deep in the vein we could capture the local pulmonary vein electrogram with latency and exit to the atrial myocardium generating a superiorly directed P wave. We believe that the area of exit was small as indicated by the fact that isolation was achieved with a single point lesion. The delay on the distal coronary sinus catheter argues against ligament of Marshall capture. Many reasons could explain our finding. It is plausible that the location of the left inferior pulmonary vein was inferior enough in the left atrium to generate a negative vector in the frontal plane. However, this could not be supported by fluoroscopy or the electro-anatomical map in our case as the inferior veins were located in the upper half of the left atrium. Alternatively, scarring in the superior left atrium is likely to have decreased the excitable mass of tissue superior to the exit site of the vein. This is also unlikely to be the sole explanation, however, as no additional ablation was performed other than on the ostia of the pulmonary veins. We believe that the morphology of the P wave was due to the obligatory exit of electrical conduction to the anterior-inferior aspect of the vein. Whether the typically inferiorly directed P wave originating from the unablated inferior veins is a result of preferential exit in the superior aspect of the vein is not known. Ablation at the ostia of pulmonary veins may change the typical exit of electrical conduction originating from those structures and therefore limits the application of previously validated algorithms to predict the site of origin for atrial ectopy. These data should be used with caution when counseling such patients.