title: Regional electrophysiological effects of left ventricular hypertrophy in isolated rabbit hearts under normal and ischaemic conditions.
abstract: OBJECTIVE
  Left ventricular hypertrophy (LVH) has been reported to produce differential electrophysiological effects in isolated epicardial and endocardial cells. This study aimed to examine regional electrophysiological effects of LVH in normal and ischaemic conditions in the whole heart.
  
  
  METHODS
  LVH was secondary to perinephritis-induced hypertension. Monophasic action potential duration (MAPD(90)), effective refractory period (ERP) and conduction delay were measured in paced, isolated working rabbit hearts either at one right ventricular and two left ventricular sites (apical and basal epicardium) or at three left ventricular sites (apical and basal epicardium, apical endocardium). The hearts were subjected to 30 min of regional ischaemia and 15 min of reperfusion.
  
  
  RESULTS
  In non-ischaemic conditions, LVH produced uniform prolongation of MAPD(90) and ERP in the left ventricular epicardium, but not in the endocardium. After coronary artery occlusion, LVH significantly increased ischaemia-induced transepicardial dispersion of repolarisation, but not refractoriness. LVH did not affect arrhythmogenesis in either non-ischaemic or ischaemic conditions.
  
  
  CONCLUSIONS
  Differential effects of LVH on epicardial and endocardial electrophysiological parameters are also observed in the whole heart. In addition, the sensitivity of hypertrophied myocardium to ischaemia is increased and leads to an increase in ischaemia-induced dispersion of repolarisation. However, neither dispersion of refractoriness nor arrhythmogenesis are affected by LVH in non-ischaemic or ischaemic conditions in this experimental model.
authors.affiliation: Department of Cardiology, Medical Center for Postgraduate Education, Grochowski Hospital, Grenadierow 51/59, 04-073, Warsaw, Poland.
authors.forename: R
authors.initials: R
authors.lastname: Wolk
authors.forename: K P
authors.initials: KP
authors.lastname: Sneddon
authors.forename: J
authors.initials: J
authors.lastname: Dempster
authors.forename: K A
authors.initials: KA
authors.lastname: Kane
authors.forename: S M
authors.initials: SM
authors.lastname: Cobbe
authors.forename: M N
authors.initials: MN
authors.lastname: Hicks
mesh_terms: D000200:Action Potentials; D000704:Analysis of Variance; D000818:Animals; D004699:Endocardium / Q000503:physiopathology; D006321:Heart / Q000503:physiopathology*; D017379:Hypertrophy, Left Ventricular / Q000503:physiopathology*; D008297:Male; D017202:Myocardial Ischemia / Q000503:physiopathology*; D015425:Myocardial Reperfusion; D010496:Pericardium / Q000503:physiopathology; D011817:Rabbits