Heart rhythm · 2010
Rate-dependent action potential alternans in human heart failure implicates abnormal intracellular calcium handling.
СтатьяПоддержка NIH: внешняя программаПоддержка исследования: вне правительства СШАНазвание и аннотация: Перевод пока не подготовлен
Обработка статьи · этапы, ошибки и управление
Загрузка состояния…
Ошибки и ограничения
История · было → стало
Состояние обновляется каждые 5 секунд, пока блок открыт. Процент показывается только там, где известен объём работы. Пауза останавливает продолжение этапа; текущий запрос к источнику может завершиться.
Bayer Jason D, Narayan Sanjiv M, Lalani Gautam G, Trayanova Natalia A
Аннотация
BACKGROUND: Alternans in action potential voltage (APV-ALT) at heart rates <110 bpm is a novel index to predict ventricular arrhythmias. However, the rate dependency of APV-ALT and its mechanisms in failing versus nonfailing human myocardium are poorly understood. It is hypothesized that APV-ALT in human heart failure (HF) reflects abnormal calcium handling.
OBJECTIVE: Using a modeling and clinical approach, our objectives were to (1) determine how APV-ALT varies with pacing rate and (2) ascertain whether abnormalities in calcium handling explain the rate dependence of APV-ALT in HF.
METHODS: APV-ALT was analyzed at several cycle lengths (CLs) using a dynamic pacing protocol applied to a human left ventricle wedge model with various alterations in calcium handling. Modeled APV-ALT was used to predict APV-ALT in left ventricle monophasic action potentials recorded from HF (n = 3) and control (n = 2) patients with the same pacing protocol.
RESULTS: Reducing the sarcoplasmic reticulum calcium uptake current < or =25%, the release current < or =11%, or the sarcolemmal L-type calcium channel current < or =43% of control predicted APV-ALT to arise at CL > or =600 ms and then increase in magnitude by >400% for CL <400 ms. In HF patients, APV-ALT arose at CL = 600 ms and then increased in magnitude by >500% at CL <350 ms. For all other model alterations and for control patients, APV-ALT occurred only at CL <500 ms.
CONCLUSIONS: APV-ALT shows differing rate dependence in HF versus control patients, arising at slower rates in HF and predicted by models with abnormal calcium handling. Future studies should investigate whether APV-ALT at slow rates identifies patients with deranged calcium handing, including HF patients before decompensation or at risk for arrhythmias.
OBJECTIVE: Using a modeling and clinical approach, our objectives were to (1) determine how APV-ALT varies with pacing rate and (2) ascertain whether abnormalities in calcium handling explain the rate dependence of APV-ALT in HF.
METHODS: APV-ALT was analyzed at several cycle lengths (CLs) using a dynamic pacing protocol applied to a human left ventricle wedge model with various alterations in calcium handling. Modeled APV-ALT was used to predict APV-ALT in left ventricle monophasic action potentials recorded from HF (n = 3) and control (n = 2) patients with the same pacing protocol.
RESULTS: Reducing the sarcoplasmic reticulum calcium uptake current < or =25%, the release current < or =11%, or the sarcolemmal L-type calcium channel current < or =43% of control predicted APV-ALT to arise at CL > or =600 ms and then increase in magnitude by >400% for CL <400 ms. In HF patients, APV-ALT arose at CL = 600 ms and then increased in magnitude by >500% at CL <350 ms. For all other model alterations and for control patients, APV-ALT occurred only at CL <500 ms.
CONCLUSIONS: APV-ALT shows differing rate dependence in HF versus control patients, arising at slower rates in HF and predicted by models with abnormal calcium handling. Future studies should investigate whether APV-ALT at slow rates identifies patients with deranged calcium handing, including HF patients before decompensation or at risk for arrhythmias.