title: Acute effects of simvastatin to terminate fast reentrant tachycardia through increasing wavelength of atrioventricular nodal reentrant tachycardia circuit.
abstract: Simvastatin (SV) leads to reduction of ventricular rhythm during atrial fibrillation on rabbit atrioventricular (AV) nodes. The aim of our study was (i) to determine the frequency-dependent effects of SV in a functional model, and (ii) to assess the effects of SV to suppress experimental AV nodal reentrant tachycardia (AVNRT). Selective stimulation protocols were used with two different pacing protocols, His to atrial, and atrial to atrial (AA). An experimental AVNRT model with various cycle lengths was created in three groups of perfused rabbit AV nodal preparations (n = 24) including: SV 3 μm, SV 7 μm, and verapamil 0.1 μm. SV increased nodal conduction time and refractoriness by AA pacing. Different simulated models of slow/fast and fast/slow reentry were induced. SV caused inhibitory effects on the slow anterograde conduction (origin of refractoriness) more than on the fast anterograde conduction time, leading to an increase of tachycardia cycle length, tachycardia wavelength and termination of slow/fast reentrant tachyarrhythmia. Verapamil significantly suppressed the basic and frequency-dependent intrinsic nodal properties. In addition, SV decreased the incidence of gap and echo beats. The present study showed that SV in a concentration and rate-dependent manner increased the AV effective refractory period and reentrant tachycardia wavelength that lead to slowing or termination of experimental fast AVNRT. The direction-dependent inhibitory effect of SV on the anterograde and retrograde dual pathways explains its specific antireentrant actions.
authors.affiliation: Ischemic Disorders Research Center, Golestan University of Medical Sciences, 49175553, Gorgan, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Khori
authors.forename: Ali Mohammad
authors.initials: AM
authors.lastname: Alizadeh
authors.forename: Hamid Reza
authors.initials: HR
authors.lastname: Moheimani
authors.forename: Mahdi
authors.initials: M
authors.lastname: Zahedi
authors.forename: Soroosh
authors.initials: S
authors.lastname: Aminolsharieh Najafi
authors.forename: Delaram
authors.initials: D
authors.lastname: Shakiba
authors.forename: Mohsen
authors.initials: M
authors.lastname: Nayebpour
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac; D001281:Atrial Fibrillation / Q000188:drug therapy; D001283:Atrioventricular Node / Q000187:drug effects*; D053840:Brugada Syndrome; D000075224:Cardiac Conduction System Disease; D004562:Electrocardiography / Q000379:methods; D006329:Heart Conduction System / Q000002:abnormalities / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D011817:Rabbits; D019821:Simvastatin / Q000494:pharmacology*; D013610:Tachycardia / Q000188:drug therapy*; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000188:drug therapy*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D019821:Simvastatin; D014700:Verapamil
keywords: atrioventricular nodal reentrant tachycardia; atrioventricular node; functional model; simvastatin; slow pathway