title: Autonomic and pharmacological responses of idiopathic ventricular tachycardia arising from the left ventricular outflow tract.
abstract: BACKGROUND
  It is well recognized that the mechanism of idiopathic ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT) is mostly due to cyclic AMP-mediated triggered activity. The mechanism of VT arising from the left ventricular outflow tract (LVOT) has not been well clarified whether it is the same as VT of RVOT.
  
  
  METHODS
  We studied autonomic modulations and pharmacological interventions on VT/premature ventricular contractions (PVCs) from LVOT to explore its possible mechanism in six patients (age: 49 +/- 14, three males). None of them had structural heart diseases.
  
  
  RESULTS
  Isoproterenol application easily induced VT and/or PVCs from LVOT. Valsalva maneuvers suppressed isoproterenol-induced VT in two and PVCs in two, and carotid sinus massage (CSM) suppressed PVCs in one patient. Adenosine triphosphate inhibited both VT and PVCs in all six patients. Propranolol, lidocaine, and procainamide eliminated VT/PVCs in four, three, and four patients, respectively. Verapamil terminated VT in one and PVCs in another one patient, but aggravated PVCs to VT in one patient.
  
  
  CONCLUSIONS
  The results suggest that the mechanism of VT from LVOT is mostly due to cAMP-mediated triggered activity as similar to that in VT from RVOT.
authors: Department of Cardiology, Yokohama Minami Kyosai Hospital, Kanagawa, Japan. yamawake-ind@umin.ac.jp
authors: Noriyoshi
authors: N
authors: Yamawake
authors: Mitsuhiro
authors: M
authors: Nishizaki
authors: Tatsuya
authors: T
authors: Hayashi
authors: Saori
authors: S
authors: Niki
authors: Shingo
authors: S
authors: Maeda
authors: Yasuaki
authors: Y
authors: Tanaka
authors: Hiroyuki
authors: H
authors: Fujii
authors: Takashi
authors: T
authors: Ashikaga
authors: Harumizu
authors: H
authors: Sakurada
authors: Masayasu
authors: M
authors: Hiraoka
mesh_terms: D000255:Adenosine Triphosphate / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D002316:Cardiotonic Agents / Q000627:therapeutic use; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D007545:Isoproterenol / Q000627:therapeutic use; D008012:Lidocaine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011342:Procainamide / Q000627:therapeutic use; D011433:Propranolol / Q000627:therapeutic use; D017180:Tachycardia, Ventricular / Q000188:drug therapy / Q000209:etiology* / Q000503:physiopathology* / Q000601:surgery; D016896:Treatment Outcome; D014636:Valsalva Maneuver; D014694:Ventricular Outflow Obstruction / Q000150:complications*
chemical_list: D000889:Anti-Arrhythmia Agents; D002316:Cardiotonic Agents; D000255:Adenosine Triphosphate; D008012:Lidocaine; D011433:Propranolol; D011342:Procainamide; D007545:Isoproterenol