the complete cycle of events in the heart from the beginning of one heart beat to the beginning of the next; an electrical impulse in conducted through the heart muscle that constricts the atria which is followed by constriction of the ventricles是什么意思_the complete cycle of events in the heart from the beginning of one heart beat to the beginning of the next; an electrical impulse in conducted through the heart muscle that constricts the atria which is followed by constriction of the ventricles在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句