{"id":18172,"date":"2014-12-02T02:41:48","date_gmt":"2014-12-02T02:41:48","guid":{"rendered":"https:\/\/cardiophile.org\/?p=18172"},"modified":"2023-01-13T06:39:34","modified_gmt":"2023-01-13T01:09:34","slug":"ecg-changes-in-hypokalemia-mechanism","status":"publish","type":"post","link":"https:\/\/johnsonfrancis.org\/professional\/ecg-changes-in-hypokalemia-mechanism\/","title":{"rendered":"ECG changes in hypokalemia: Mechanism"},"content":{"rendered":"<p><iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/lJK0cnEtYUM\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen=\"\"><\/iframe><\/p>\n<h2><span style=\"color: #008000;\">ECG changes in hypokalemia: Mechanism<\/span><\/h2>\n<p>Serum potassium levels below 3.5 mEq\/L is considered as hypokalemia. Hypokalemia can occur due to gastrointestinal or renal potassium loss or due to shift from extracellular to intracellular compartment as occurs in alkalosis. Myocardium is very sensitive to the effects of hypokalemia, which may be exacerbated in the presence of ischemia or digoxin toxicity.<\/p>\n<p>Electrocardiographic changes are an important feature of hypokalemia. As the serum potassium levels fall, the T waves become flattened and may disappear. The U wave becomes more prominent as hypokalemia worsens. This in effect will produce an apparent prolongation of QT interval, though it is actually the QU interval which is often manifest.<\/p>\n<p><span style=\"color: #0000ff;\">Prolongation of action potential duration in hypokalemia is due to inhibition of the outward potassium current.<\/span> <em>I<sub>Kr<\/sub>, the rapid component of the delayed rectifier potassium current, is markedly suppressed in hypokalemia.<\/em> There is rapid inactivation of I<sub>Kr<\/sub>&nbsp;during repolarization. Downregulation of I<sub>Kr&nbsp;<\/sub>occurs in chronic hypokalemia. In addition chronic hypokalemia causes internalization of I<sub>Kr&nbsp;<\/sub>channels, reducing their surface density on the plasma membrane.<\/p>\n<p>Prolongation of action potential duration with hypokalemia increases the chance of ventricular arrhythmias by potentiating after depolarization. When the afterdepolarizations reach a threshold value, they trigger a ventricular ectopic beat which can induce sustained ventricular arrhythmias in this setting.<\/p>\n<p>Shortened effective refractory period is another reason for arrhythmias in hypokalemia. Even though the action potential duration is prolonged in hypokalemia, there is no corresponding lengthening of refractory period. This predisposes to perpetuation of arrhythmia induced by the afterdepolarizations.<\/p>\n<p>Hypokalemia slows the conduction in the AV node by potentiating the effect of acetylcholine on suppressing the atrioventricular conduction. Hypokalemia induced membrane hyperpolarization is thought to have a role in this negative dromotropic effect.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Prolongation of action potential duration in hypokalemia is due to inhibition of the outward potassium current. IKr, the rapid component of the delayed rectifier potassium current, is markedly suppressed in hypokalemia.<\/p>\n","protected":false},"author":1,"featured_media":58082,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","footnotes":""},"categories":[6],"tags":[],"class_list":["post-18172","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ecg-electrophysiology"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.9 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>ECG changes in hypokalemia: Mechanism - suppression of IKr<\/title>\n<meta name=\"description\" content=\"ECG changes in hypokalemia: Mechanism: IKr, the rapid component of the delayed rectifier potassium current, is suppressed in hypokalemia\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/johnsonfrancis.org\/professional\/ecg-changes-in-hypokalemia-mechanism\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"ECG changes in hypokalemia: Mechanism - 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