心脏节律不整，常简称为心律不整、心律失常、心律不齐（英语：cardiac arrhythmia，或称cardiac dysrhythmia、irregular heartbeat），是指心脏电传导系统异常所引起的各种症状，包含心跳不规则、过快、或过慢的表现总称。其中心搏过速（或称频脉）的定义是成人每分钟心跳大于100下，而心搏过缓（或称缓脉）的定义是成人每分钟心跳小于60下。许多心律不整表现是无症状的，一旦有症状则常以心悸或心跳暂停的感觉表现。严重的心律不整会导致头晕、昏厥、呼吸困难或胸痛。即使大部分情况是良性的，有些心律不整却会增加中风或心脏衰竭等并发症的风险，甚至导致心跳骤停、休克、猝死。

Cardiac arrhythmia, also known as cardiac dysrhythmia or irregular heartbeat, is a group of conditions in which the heartbeat is irregular, too fast, or too slow. A heartbeat that is too fast - above 100 beats per minute in adults - is called tachycardia and a heartbeat that is too slow - below 60 beats per minute - is called bradycardia. Many types of arrhythmia have no symptoms. When symptoms are present these may include palpitations or feeling a pause between heartbeats. More seriously there may be lightheadedness, passing out, shortness of breath, or chest pain. While most types of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure. Others may result in cardiac arrest.