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Kim, Sook Kyoung,Pak, Hui-Nam,Park, Yongdoo S. Karger AG 2014 Cardiology Vol.128 No.1
<P>Abstract</P><P><B><I>Objectives:</I></B> Bradycardia is caused by loss-of-function mutations in potassium channels that regulate phase 3 repolarization of the cardiac action potential. The purpose of this study is to monitor the effects of potassium channel (KCNQ1) inhibition and to evaluate the effects of isoproterenol (ISO) and MgSO<SUB>4</SUB> in restoring sinus rhythm in atrial cells. <B><I>Methods:</I></B> Microelectrode array was used to analyze conduction velocity, voltage amplitude and cycle length of atrial cells (HL-1). A combination of ISO and MgSO<SUB>4</SUB> was used to restore sinus rhythm in these cells. <B><I>Results:</I></B> mRNA expression levels of KCNQ1 (42.2 vs. 100%, p < 0.0001), connexin 43 (29.6 vs. 100%, p = 0.0033), atrial natriuretic peptide (31.0 vs. 100%, p = 0.0030), cardiac actin (38.2 vs. 100%, p < 0.0001) and α-myosin heavy chain (31.2 vs. 100%, p = 0.00254) were significantly lower in the KCNQ1 gene-inhibited group compared to the control group. When treated with MgSO<SUB>4</SUB> (1 m<smlcap>M</smlcap>) and ISO (10 μ<smlcap>M</smlcap>), conduction velocity (0.0208 ± 0.0036 vs. 0.0086 ± 0.0014 m/s, p = 0.0004) and voltage amplitude (1,210.78 ± 65.81 vs. 124.1 ± 13.30 μV, p < 0.0001) were higher, and cycle length (431.55 ± 2.05 vs. 1,015.15 ± 4.31 ms, p < 0.0001) was shorter than in the gene-inhibited group. <B><I>Conclusion:</I></B> Inhibition of sinus rhythm in the bradycardia cell model was recovered by treatment with ISO and MgSO<SUB>4</SUB>, demonstrating the potency of combination therapy in the treatment of bradycardia.</P><P>© 2014 S. Karger AG, Basel</P>
PARK, JAE HYUNG,PAK, HUI-NAM,CHOI, EUN JEOUNG,JANG, JIN KUN,KIM, SOOK KYOUNG,CHOI, DONG HOON,CHOI, JONG IL,HWANG, CHUN,KIM, YOUNG-HOON Blackwell Publishing Inc 2009 Journal of cardiovascular electrophysiology Vol.20 No.12
<P><I>Background:</I> Long-standing atrial fibrillation (AF) changes left atrial (LA) morphology, and the LA size is related to recurrence after radiofrequency catheter ablation (RFCA). We hypothesize that LA morphology, based on embryological origin, affects the outcome of RFCA.</P><P><I>Methods:</I> We analyzed 3D computed tomographic (CT) images of LA in 70 patients with AF (54 males, 55.6 ± 10.5 years old, paroxysmal AF (PAF):persistent AF (PeAF) = 32:38) who underwent RFCA. Each LA image was divided into venous atrium (VA), anterior LA (ALA), LA appendage (LAA), and both antrum. Absolute and relative volumes were calculated, and the lengths of linear ablation sites were measured.</P><P><I>Results:</I> (1) In patients with the mean LA voltage ≤ 2.0 mV, LA volume, especially ALA, was larger (P < 0.01) compared to those with LA voltage > 2.0 mV. (2) The total LA volume was significantly larger (P < 0.01) and LAA voltages (P < 0.05) and conduction velocities (P < 0.05) were lower in patients with PeAF than in those with PAF. (3) In patients with recurrence, LA volume was generally larger (P < 0.01) than in those without recurrence. In PAF patients with recurrence, the relative volume of ALA was significantly larger (P < 0.01) than those without recurrence.</P><P><I>Conclusions</I> Morphologically remodeled LA has low endocardial voltage, and enlargement of ALA is more significant in electroanatomically remodeled LA. The disproportional enlargement of ALA was observed more often in PAF patients with recurrence after ablation than those without recurrence.</P>