title: Ubiquitous myocardial extensions into the pulmonary artery demonstrated by integrated intracardiac echocardiography and electroanatomic mapping: changing the paradigm of idiopathic right ventricular outflow tract arrhythmias.
abstract: BACKGROUND
  Idiopathic ventricular arrhythmias of left bundle branch block inferior axis morphology are usually localized to the right ventricular outflow tract (RVOT), presumably below the pulmonic valve (PV). However, the PV location is usually not confirmed by direct visualization.
  
  
  RESULTS
  Intracardiac echocardiography was used to visualize and tag the PV annulus, which was then integrated with 3-dimensional voltage maps of the RVOT. Distances were measured from the furthest extent of myocardial signal (bipolar voltage ≥1.5 mV) to the PV annulus. This was performed in 24 control patients and 24 prospective patients with RVOT arrhythmias. Myocardial signal beyond the PV was found in 92% of controls and 88% of RVOT arrhythmia patients (P=1.000). Average myocardial extension was further on the septal side than on the free wall side for control patients (5.6 mm; interquartile range [IQR], 3.6-7.7, versus 1.7 mm; IQR (-)0.1 to (+)4.0; P=0.002) and RVOT arrhythmia patients (5.7 mm; IQR, 2.7-7.7, versus 1.4 mm; IQR, (-)0.8 to (+)4.8; P=0.004). Eleven (46%) RVOT arrhythmia foci were localized beyond the valve in the pulmonary artery (median 8.2 mm above PV; IQR, 6.6-10.3 mm); these locations were confirmed as supravalvular by direct intracardiac echocardiography visualization.
  
  
  CONCLUSIONS
  Myocardial voltage extension into the pulmonary artery in humans is ubiquitous and can be demonstrated in vivo using 3-dimensional integrated intracardiac echocardiography to localize the PV. These extensions frequently serve as origins of presumed RVOT arrhythmias; intracardiac echocardiography localization of the PV allows reclassification of these as pulmonary arterial arrhythmias.
authors.affiliation: From the Division of Cardiology, Weill Cornell Medical College, New York, NY. CHL7001@med.cornell.edu.
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Liu
authors.affiliation: From the Division of Cardiology, Weill Cornell Medical College, New York, NY.
authors.forename: Jim W
authors.initials: JW
authors.lastname: Cheung
authors.affiliation: From the Division of Cardiology, Weill Cornell Medical College, New York, NY.
authors.forename: George
authors.initials: G
authors.lastname: Thomas
authors.affiliation: From the Division of Cardiology, Weill Cornell Medical College, New York, NY.
authors.forename: James E
authors.initials: JE
authors.lastname: Ip
authors.affiliation: From the Division of Cardiology, Weill Cornell Medical College, New York, NY.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Markowitz
authors.affiliation: From the Division of Cardiology, Weill Cornell Medical College, New York, NY.
authors.forename: Bruce B
authors.initials: BB
authors.lastname: Lerman
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011664:Pulmonary Valve / Q000000981:diagnostic imaging / Q000503:physiopathology; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D014463:Ultrasonography; D018879:Ventricular Premature Complexes / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology
keywords: intracardiac imaging techniques; pulmonary artery; pulmonary valve; ventricular tachycardia