The purpose of the present study is to provide guidelines regarding risk factors that may worsen the Long-QT Syndrome (LQTS), based on available literature. This review evaluates the current knowledge on these risk fa...The purpose of the present study is to provide guidelines regarding risk factors that may worsen the Long-QT Syndrome (LQTS), based on available literature. This review evaluates the current knowledge on these risk factors of acquired LQTS, with an emphasis on non genetic risk factors, including environmental factors. PubMed was searched for literature in English from 1999 to 2011 on the molecular and clinical studies of Long-QT syndrome. We agree, with recent investigations described in the literature, that variety of factors, inherited or environmental, can influence expression of ion channel proteins with impact on repolarization.展开更多
Objectives To explore the optimized program-control mode of a dual-chamber pacemaker combined withβ-blocker to treat congenital long QT syndrome(LQTS). Methods 12 LQTS patients in our hospital that still have symptom...Objectives To explore the optimized program-control mode of a dual-chamber pacemaker combined withβ-blocker to treat congenital long QT syndrome(LQTS). Methods 12 LQTS patients in our hospital that still have symptoms despite use of regular drug therapies or that can not endure the therapies were implanted with DDD cardiac pacemaker.The QT/QTc intervals of those patients were measured at different pacing rates respectively.Their cardiac pacemakers were all programmed to selectively turn on and turn off some related functions at the pacing rate of 80 beats/min.The dosage ofβ-blockers was adjusted according to the patients’ PR intervals and blood pressures.The MACE and the cardiac function of the patients were recorded after operation.Results The measured QT / QTc interval decreased with the pacing rate increasing.The pacing rate of 80 beats/min can make QT/QTc interval basically normal. The MACE of the patients were statistically declined(P = 0.003) and no negative effect on cardiac function was found during the follow-up.Conclusions The optimized program-control mode of a dual-chamber pacemaker combined withβ-blocker to treat congenital LQTS are:to pace at the rate of 80 beats/min and program to turn off lag,sleep,automatic preventing PMT and automatic threshold-capture feature and turn on the PVC,rate adaptation and atrioventricular node priority function.展开更多
Background Congenital long QT syndrome （LQTS） is an inherited ion channel disorder resulting in abnormal cardiac repolarization that can cause syncope and sudden death associated with a prolonged rate-corrected QT i...Background Congenital long QT syndrome （LQTS） is an inherited ion channel disorder resulting in abnormal cardiac repolarization that can cause syncope and sudden death associated with a prolonged rate-corrected QT interval and polymorphic ventricular tachycardia. Several studies in adults showed that LQTS patients have altered QT adaptation to heart rate changes compared with normal subjects which forming a ＂hysteresis loop＂ in the QT-circle length plot. This study was to observe the QT interval changing during exercise testing in children long QT syndrome （LQTS） patients, explore the new diagnosis methods of LQTS. Methods The subjects were divided into 3 groups according to 1993 LQTS diagnostic criteria. Group 1： LQTS group （n=17） who scored 〉 or = 4 points indicating definite LQTS. Group 2： Middle group （n=16）, patients who have prolonged QT interval but scored 1.5 to 3.5. Group 3： Normal control group （n=18）. The average age of all study population is （12.3±5.8） years. No case had beta-adrenergic antagonists administration before exercise testing. All subjects were underwent tread mill exercise testing and electrocardiograph in whole exercise testing and recovery were recorded. QT and heart rate changing during whole exercise testing period were recorded. /kQT, the QT interval at 1, 2, 4, 6 minutes into recovery subtract from the QT interval at a similar heart rate during exercise, were calculated. Results In all three groups, QT intervals were shortening with the increasing of heart rate, but QTc had no significant change. ΔQT at 1 minute （（45±11） ms）, 2 minutes （（37±15） ms）, 4 minutes （（23±12） ms） into recovery in LQTS group were significantly greater than that of the other two groups （P〈0.05, P〈0.01, P〈0.01, respectively）. There was no ΔQT significant difference between middle group and normal control group at recovery time. During the recovery phase in LQTS group, the QT interval remained shortened despite a decelerating heart rate, forming a hysteresis ＂loop＂ in the curve relating the QT interval to the cycle length. Conclusions In children LQTS patients, there is significant QT hysteresis loop in the relation of QT interval with heart rate during recovery of exercise testing, which could be useful to the early diagnosis for LQTS.展开更多
文摘The purpose of the present study is to provide guidelines regarding risk factors that may worsen the Long-QT Syndrome (LQTS), based on available literature. This review evaluates the current knowledge on these risk factors of acquired LQTS, with an emphasis on non genetic risk factors, including environmental factors. PubMed was searched for literature in English from 1999 to 2011 on the molecular and clinical studies of Long-QT syndrome. We agree, with recent investigations described in the literature, that variety of factors, inherited or environmental, can influence expression of ion channel proteins with impact on repolarization.
文摘Objectives To explore the optimized program-control mode of a dual-chamber pacemaker combined withβ-blocker to treat congenital long QT syndrome(LQTS). Methods 12 LQTS patients in our hospital that still have symptoms despite use of regular drug therapies or that can not endure the therapies were implanted with DDD cardiac pacemaker.The QT/QTc intervals of those patients were measured at different pacing rates respectively.Their cardiac pacemakers were all programmed to selectively turn on and turn off some related functions at the pacing rate of 80 beats/min.The dosage ofβ-blockers was adjusted according to the patients’ PR intervals and blood pressures.The MACE and the cardiac function of the patients were recorded after operation.Results The measured QT / QTc interval decreased with the pacing rate increasing.The pacing rate of 80 beats/min can make QT/QTc interval basically normal. The MACE of the patients were statistically declined(P = 0.003) and no negative effect on cardiac function was found during the follow-up.Conclusions The optimized program-control mode of a dual-chamber pacemaker combined withβ-blocker to treat congenital LQTS are:to pace at the rate of 80 beats/min and program to turn off lag,sleep,automatic preventing PMT and automatic threshold-capture feature and turn on the PVC,rate adaptation and atrioventricular node priority function.
文摘Background Congenital long QT syndrome （LQTS） is an inherited ion channel disorder resulting in abnormal cardiac repolarization that can cause syncope and sudden death associated with a prolonged rate-corrected QT interval and polymorphic ventricular tachycardia. Several studies in adults showed that LQTS patients have altered QT adaptation to heart rate changes compared with normal subjects which forming a ＂hysteresis loop＂ in the QT-circle length plot. This study was to observe the QT interval changing during exercise testing in children long QT syndrome （LQTS） patients, explore the new diagnosis methods of LQTS. Methods The subjects were divided into 3 groups according to 1993 LQTS diagnostic criteria. Group 1： LQTS group （n=17） who scored 〉 or = 4 points indicating definite LQTS. Group 2： Middle group （n=16）, patients who have prolonged QT interval but scored 1.5 to 3.5. Group 3： Normal control group （n=18）. The average age of all study population is （12.3±5.8） years. No case had beta-adrenergic antagonists administration before exercise testing. All subjects were underwent tread mill exercise testing and electrocardiograph in whole exercise testing and recovery were recorded. QT and heart rate changing during whole exercise testing period were recorded. /kQT, the QT interval at 1, 2, 4, 6 minutes into recovery subtract from the QT interval at a similar heart rate during exercise, were calculated. Results In all three groups, QT intervals were shortening with the increasing of heart rate, but QTc had no significant change. ΔQT at 1 minute （（45±11） ms）, 2 minutes （（37±15） ms）, 4 minutes （（23±12） ms） into recovery in LQTS group were significantly greater than that of the other two groups （P〈0.05, P〈0.01, P〈0.01, respectively）. There was no ΔQT significant difference between middle group and normal control group at recovery time. During the recovery phase in LQTS group, the QT interval remained shortened despite a decelerating heart rate, forming a hysteresis ＂loop＂ in the curve relating the QT interval to the cycle length. Conclusions In children LQTS patients, there is significant QT hysteresis loop in the relation of QT interval with heart rate during recovery of exercise testing, which could be useful to the early diagnosis for LQTS.
