Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations.

Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations. Research Abstract Details 

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Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations. Abstract Text:

Bruce D Walker,Andrew D Krahn,George J Klein,Allan C Skanes,Raymond Yee,Jian Wang,Robert A Hegele,

INTRODUCTION: Congenital long QT syndrome (LQTS) is characterized by syncope and cardiac arrest, often in association with exercise or sudden arousal. It was hypothesized that patients with LQTS with human ether-a-go-go-related gene (HERG) mutations (LQT2) have an abnormal QT adaptation to changes in heart rate induced by exercise and that such abnormalities may be ameliorated by treatment with beta-adrenoreceptor blockers. METHODS AND RESULTS: Sixteen LQT2 patients (26+/-15 years of age, 10 female) and 27 healthy volunteers (34+/-16 years of age, 17 female) had 12-lead electrocardiograms recorded while supine, immediately on standing and continuously during treadmill exercise testing. Changing from supine to standing alone caused a significant increase in QTc in the LQT2 group compared with in control subjects (change in QTc of 48+/-38 ms versus 21+/-29 ms, respectively, P=0.02). While QT and QTc remained longer in LQT2 patients at peak exercise, QT shortening (QT peak minus QT supine) was greater in LQT2 patients than in control subjects (-158+/-32 ms versus -117+/-32 ms, P<0.001). Beta-blocker treatment had no effect on the resting QTc, but it normalized the increase in QTc on standing (45+/-29 ms before beta-blocker versus 23+/-32 ms after beta-blocker, P=0.03). During exercise, QT shortening and peak QTc were not affected by beta-blocker treatment. CONCLUSIONS: Abnormal repolarization in LQT2 is accentuated by a change in posture and exercise. Beta-blockers normalize the QTc prolongation elicited by such manoeuvres.

Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations. Publishing Authors By Initials

BD Walker,AD Krahn,GJ Klein,AC Skanes,R Yee,J Wang,RA Hegele,

For similar circulatory and respiratory physiology: cardiovascular physiology: cardiovascular physiologic processes: ventricular function: ventricular remodeling research abstracts see: circulatory and respiratory physiology: cardiovascular physiology: cardiovascular physiologic processes: ventricular function: ventricular remodeling research

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Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations. Journal Published:

PUBLICATION TYPE: Journal Article

Journal: The Canadian journal of cardiology

VOLUME: 21

Page Numbers: 33-8

Journal Abbreviation:

ISSN: 1916-7075

DAY: 3

MONTH: Jan

YEAR: 2005

Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations. Information

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LANGUAGE: eng

NlmUniqueID: 8510280

Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations. Keywords Mesh Terms:

KEYWORDS: Ventricular Remodeling

MESH TERMS: genetics

Chemical & Substance for Abstract: Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations. Information

Substance Name: Potassium Channels, Voltage-Gated

Registry Number: 0

Grant and Affiliation Information for Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations.

AFFILIATION: Division of Cardiology and the Blackburn Genetics Laboratory, Roberts Research Institute, University of Western Ontario, London.

Country: Canada

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MEDLINETA: Can J Cardiol

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