Wan-Ping Zhou1,2, Fen Li3, Jin-Jin Wu1, Ya-Nan Lu1, Yi-Jiao Qian1. 1. Cardiology Department, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, 1678 Dongfang Road, Pudong New Area, 200127, Shanghai, China. 2. Cardiology Department, Children's Hospital of Soochow University, Suzhou, China. 3. Cardiology Department, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, 1678 Dongfang Road, Pudong New Area, 200127, Shanghai, China. lifen@scmc.com.cn.
Abstract
BACKGROUND: Atrial tachyarrhythmia (AT) is a common complication in patients who have undergone a Fontan operation. In this study, we investigated whether abnormal Ca2+ handling contributes to the Fontan operation-related atrial arrhythmogenic substrate. METHODS: Mongrel dogs were randomly assigned to sham and Fontan groups. The Fontan operation model was developed by performing an atriopulmonary anastomosis. After 14 days, an electrophysiological study was performed to evaluate the AT vulnerability. Ca2+ handling properties were measured by loading atrial cardiomyocytes (CMs) with fura-2 AM. The L-type Ca2+ (ICa-L) and Na+-Ca2+ exchanger (INCX) currents of the CMs were recorded by the whole-cell patch-clamp technique. The key Ca2+ handling proteins expression was assessed by Western blotting. RESULTS: The AT inducibility was higher in the Fontan group than in the sham group (85.71 vs. 14.29%, P < 0.05). The Fontan operation resulted in decreased Ca2+ transient (CaT) amplitude and sarcoplasmic reticulum (SR) Ca2+ content, but in enhanced diastolic intracellular Ca2+ concentration and SR Ca2+ leak in the atrial CMs. The spontaneous CaT events, triggered ectopic activity and INCX density were increased, but ICa-L density was reduced in CMs from the Fontan atria (all P < 0.05). Additionally, the Fontan operation resulted in decreased SR Ca2+ ATPase expression and Cav1.2 expression, but in increased NCX1 and Ser2814-phosphorylated ryanodine receptor 2. The calmodulin-dependent protein kinase II expression and function were markedly enhanced in the Fontan atria. CONCLUSION: The Fontan operation caused atrial CM Ca2+ handling abnormalities that produced arrhythmogenic-triggered activity and increased vulnerability to AT in experimental Fontan dogs.
BACKGROUND:Atrial tachyarrhythmia (AT) is a common complication in patients who have undergone a Fontan operation. In this study, we investigated whether abnormal Ca2+ handling contributes to the Fontan operation-related atrial arrhythmogenic substrate. METHODS: Mongrel dogs were randomly assigned to sham and Fontan groups. The Fontan operation model was developed by performing an atriopulmonary anastomosis. After 14 days, an electrophysiological study was performed to evaluate the AT vulnerability. Ca2+ handling properties were measured by loading atrial cardiomyocytes (CMs) with fura-2 AM. The L-type Ca2+ (ICa-L) and Na+-Ca2+ exchanger (INCX) currents of the CMs were recorded by the whole-cell patch-clamp technique. The key Ca2+ handling proteins expression was assessed by Western blotting. RESULTS: The AT inducibility was higher in the Fontan group than in the sham group (85.71 vs. 14.29%, P < 0.05). The Fontan operation resulted in decreased Ca2+ transient (CaT) amplitude and sarcoplasmic reticulum (SR) Ca2+ content, but in enhanced diastolic intracellular Ca2+ concentration and SR Ca2+ leak in the atrial CMs. The spontaneous CaT events, triggered ectopic activity and INCX density were increased, but ICa-L density was reduced in CMs from the Fontan atria (all P < 0.05). Additionally, the Fontan operation resulted in decreased SR Ca2+ ATPase expression and Cav1.2 expression, but in increased NCX1 and Ser2814-phosphorylated ryanodine receptor 2. The calmodulin-dependent protein kinase II expression and function were markedly enhanced in the Fontan atria. CONCLUSION: The Fontan operation caused atrial CM Ca2+ handling abnormalities that produced arrhythmogenic-triggered activity and increased vulnerability to AT in experimental Fontan dogs.
Authors: M Gelatt; R M Hamilton; B W McCrindle; R M Gow; W G Williams; G A Trusler; R M Freedom Journal: J Am Coll Cardiol Date: 1994-12 Impact factor: 24.094
Authors: Niels Voigt; Jordi Heijman; Qiongling Wang; David Y Chiang; Na Li; Matthias Karck; Xander H T Wehrens; Stanley Nattel; Dobromir Dobrev Journal: Circulation Date: 2013-11-18 Impact factor: 29.690