Long QT(3) ( @entity25930 ) syndrome is associated with abnormal repolarisation kinetics, prolonged action potential durations (APD) and QT intervals and may lead to life-threatening @entity943 . However, there have been few physiological studies of its effects on atrial electrophysiology. Programmed electrical stimulation and burst pacing induced @entity955 in 16 out of 16 (16/16) wild-type (WT) and 7/16 genetically modified @entity42451 (KPQ) Langendorff-perfused @entity19 hearts modelling @entity25930 (P < 0.001 for both), and in 14/16 WT and 1/16 KPQ hearts (P < 0.001 for both; Fisher's exact test), respectively. The arrhythmogenic WT hearts had significantly larger positive critical intervals (CI), given by the difference between atrial effective refractory periods (AERPs) and action potential durations at 90% recovery (APD(90)), compared to KPQ hearts (8.1 and 3.2 ms, respectively, P < 0.001). @entity6237 prevented @entity943 in all arrhythmogenic WT (P < 0.001) and KPQ hearts (P < 0.05). It prolonged the AERP to a larger extent than it did the APD(90) in both WT and KPQ groups, giving negative CIs. @entity5126 similarly exerted anti-arrhythmic effects, prolonged AERP over corresponding APD(90) in both WT and KPQ groups. These findings, thus, demonstrate, for the first time, inhibitory effects of the KPQ mutation on atrial arrhythmogenesis and its modification by @entity6237 and @entity5126 . They attribute these findings to differences in the CI between WT and mutant hearts, in the presence or absence of these drugs. Thus, prolongation of APD(90) over AERP gave positive CI values and increased atrial arrhythmogenicity whereas lengthening of AERP over APD(90) reduced such CI values and produced the opposite effect.

Atrial arrhythmogenesis in wild-type and XXXX @entity19 hearts modelling LQT3 syndrome.

@entity19 :: ('10090', 'Species') :: ['murine'] @entity6237 :: ('MESH:D005424', 'Chemical') :: ['flecainide', 'Flecainide'] @entity5126 :: ('MESH:D011802', 'Chemical') :: ['Quinidine', 'quinidine'] @entity955 :: ('MESH:D001281', 'Disease') :: ['atrial arrhythmic episodes'] @entity25930 :: ('MESH:C537034', 'Disease') :: ['LQT3'] @entity42451 :: ('20271(Tax:10090)', 'Gene') :: ['Scn5a+/Delta'] @entity943 :: ('MESH:D001145', 'Disease') :: ['atrial arrhythmias', 'ventricular arrhythmias']
@entity42451 :: (20271(Tax:10090),Gene) :: ['Scn5a+/delta']
