Editing Heart failure (section)

===Electrophysiology===
An [[electrocardiogram]] (ECG or EKG) may be used to identify [[arrhythmia]]s, [[ischemic heart disease]], [[right ventricular hypertrophy|right]] and [[left ventricular hypertrophy]], and presence of conduction delay or abnormalities (e.g. [[left bundle branch block]]). Although these findings are not specific to the diagnosis of heart failure, a normal ECG virtually excludes left ventricular systolic dysfunction.<ref>{{cite book | vauthors = Loscalzo J, Fauci AS, Braunwald E, Kasper DL, Hauser SL, Longo DL |title=Harrison's Principles of Internal Medicine |edition=17 |publisher=McGraw-Hill Medical |year=2008 |page=1447 |isbn=978-0-07-147693-5 }}</ref>