{"id":27464,"date":"2017-01-19T16:45:51","date_gmt":"2017-01-19T16:45:51","guid":{"rendered":"https:\/\/www.mometrix.com\/academy\/?page_id=27464"},"modified":"2026-03-28T11:07:57","modified_gmt":"2026-03-28T16:07:57","slug":"ekg-interpretation","status":"publish","type":"page","link":"https:\/\/www.mometrix.com\/academy\/ekg-interpretation\/","title":{"rendered":"EKG Interpretation: Atrial Fibrillation and Atrial Flutter"},"content":{"rendered":"\n\t\t\t<div id=\"mmDeferVideoEncompass_LOu2-Xwa-Oc\" style=\"position: relative;\">\n\t\t\t<picture>\n\t\t\t\t<source srcset=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.webp\" type=\"image\/webp\">\n\t\t\t\t<source srcset=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.png\" type=\"image\/jpeg\"> \n\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" loading=\"eager\" id=\"videoThumbnailImage_LOu2-Xwa-Oc\" data-source-videoID=\"LOu2-Xwa-Oc\" src=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.png\" alt=\"EKG Interpretation: Atrial Fibrillation and Atrial Flutter Video\" height=\"464\" width=\"825\" class=\"size-full\" data-matomo-title = \"EKG Interpretation: Atrial Fibrillation and Atrial Flutter\">\n\t\t\t<\/picture>\n\t\t\t<\/div>\n\t\t\t<style>img#videoThumbnailImage_LOu2-Xwa-Oc:hover {cursor:pointer;} img#videoThumbnailImage_LOu2-Xwa-Oc {background-size:contain;background-image:url(\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/1969-thumb-final-3.webp\");}<\/style>\n\t\t\t<script defer>\n\t\t\t  jQuery(\"img#videoThumbnailImage_LOu2-Xwa-Oc\").click(function() {\n\t\t\t\tlet videoId = jQuery(this).attr(\"data-source-videoID\");\n\t\t\t\tlet helpTag = '<div id=\"mmDeferVideoYTMessage_LOu2-Xwa-Oc\" style=\"display: none;position: absolute;top: -24px;width: 100%;text-align: center;\"><span style=\"font-style: italic;font-size: small;border-top: 1px solid #fc0;\">Having trouble? <a href=\"https:\/\/www.youtube.com\/watch?v='+videoId+'\" target=\"_blank\">Click here to watch on YouTube.<\/a><\/span><\/div>';\n\t\t\t\tlet tag = document.createElement(\"iframe\");\n\t\t\t\ttag.id = \"yt\" + videoId;\n\t\t\t\ttag.src = \"https:\/\/www.youtube-nocookie.com\/embed\/\" + videoId + \"?autoplay=1&controls=1&wmode=opaque&rel=0&egm=0&iv_load_policy=3&hd=0&enablejsapi=1\";\n\t\t\t\ttag.frameborder = 0;\n\t\t\t\ttag.allow = \"autoplay; fullscreen\";\n\t\t\t\ttag.width = this.width;\n\t\t\t\ttag.height = this.height;\n\t\t\t\ttag.setAttribute(\"data-matomo-title\",\"EKG Interpretation: Atrial Fibrillation and Atrial Flutter\");\n\t\t\t\tjQuery(\"div#mmDeferVideoEncompass_LOu2-Xwa-Oc\").html(tag);\n\t\t\t\tjQuery(\"div#mmDeferVideoEncompass_LOu2-Xwa-Oc\").prepend(helpTag);\n\t\t\t\tsetTimeout(function(){jQuery(\"div#mmDeferVideoYTMessage_LOu2-Xwa-Oc\").css(\"display\", \"block\");}, 2000);\n\t\t\t  });\n\t\t\t  \n\t\t\t<\/script>\n\t\t\n<p><script>\nfunction 61u_Function() {\n  var x = document.getElementById(\"61u\");\n  if (x.style.display === \"none\") {\n    x.style.display = \"block\";\n  } else {\n    x.style.display = \"none\";\n  }\n}\n<\/script><\/p>\n<div class=\"moc-toc hide-on-desktop hide-on-tablet\">\n<div><button onclick=\"61u_Function()\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2024\/12\/toc2.svg\" width=\"16\" height=\"16\" alt=\"show or hide table of contents\"><\/button><\/p>\n<p>On this page<\/p>\n<\/div>\n<nav id=\"61u\" style=\"display:none;\">\n<ul>\n<li class=\"toc-h2\"><a href=\"#Interpreting_EKG_Strips\" class=\"smooth-scroll\">Interpreting EKG Strips<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Evaluating_a_Normal_Sinus_Rhythm\" class=\"smooth-scroll\">Evaluating a Normal Sinus Rhythm<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Atrial_Flutter\" class=\"smooth-scroll\">Atrial Flutter<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Atrial_Fibrillation_(AFib)\" class=\"smooth-scroll\">Atrial Fibrillation (AFib)<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Review\" class=\"smooth-scroll\">Review<\/a><\/li>\n<\/ul>\n<\/nav>\n<\/div>\n<div class=\"accordion\"><input id=\"transcript\" type=\"checkbox\" class=\"spoiler_button\" \/><label for=\"transcript\">Transcript<\/label>\n<div class=\"spoiler\" id=\"transcript-spoiler\">\n<p>In this video we\u2019ll be looking at how to interpret an EKG strip, specifically atrial flutter and atrial fibrillation. If you haven\u2019t already, you may want to watch our video on <a class=\"ylist\" href=\"https:\/\/www.mometrix.com\/academy\/ekg-reading\/\">basic EKG interpretation<\/a> first\u2014it goes into more detailed steps of how to read an EKG strip and is a good refresher.<\/p>\n<h2><span id=\"Interpreting_EKG_Strips\" class=\"m-toc-anchor\"><\/span>Interpreting EKG Strips<\/h2>\n<p>\nFirst we\u2019ll go over a simplified five-step approach to interpreting all EKG strips:<\/p>\n<ol>\n<li style=\"margin-bottom: 10px;\"><strong>What is the<\/strong> <a class=\"ylist\" href=\"https:\/\/www.mometrix.com\/academy\/heart-anatomy-and-physiology\/\">heart<\/a> <strong>rate<\/strong>? Count how many R waves in 6 seconds (this is the ventricular heart rate &#8211; the QRS complex represents the ventricles contracting).<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are there P waves present?<\/strong> Count how many in 6 sec. (this is the atrial heart rate &#8211; remember the P wave represents the atria contracting).<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are the P waves regular?<\/strong> Measure with calipers or a paper.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are the R waves regular?<\/strong> Again, measure with calipers or a paper.<\/li>\n<li><strong>How long is the PR interval?<\/strong> (Normally 0.12-0.20 sec.\/3-5 small squares) &amp; what is the width of the QRS complex? (normally 0.06-0.12 sec\/1.5-3 boxes).<\/li>\n<\/ol>\n<h2><span id=\"Evaluating_a_Normal_Sinus_Rhythm\" class=\"m-toc-anchor\"><\/span>Evaluating a Normal Sinus Rhythm<\/h2>\n<p>\nLet\u2019s evaluate a normal sinus rhythm using these six steps:<\/p>\n<ol>\n<li style=\"margin-bottom: 10px;\"><strong>What is the heart rate?<\/strong> Count how many R waves in six seconds and multiply by 10, or count how many in three seconds and multiply by 20. Here we have 4 R waves in three seconds, times 20, equals 80 bpm (remember normal HR falls between 60-100).<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are there P waves present? <\/strong> Since we have three seconds here, we\u2019ll multiply the number of P waves by 20, so four P waves times 20 shows an atrial rate of 80 bpm.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are the P waves regular?<\/strong> Start from the beginning of one P wave to the beginning of the next P wave, measuring with calipers or a paper. In this case, the P waves do measure out to be regular distances apart.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are the R waves regular?<\/strong> Do this again for the R waves and they also measure out equal or almost equal distances apart. There might be a slight variation in length and that is okay, we have to allow for some fluctuation in heart rate.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>How long is the PR interval?<\/strong> The PR interval (normally 0.12-0.20 sec.\/3-5 small squares) represents the time it takes an impulse to travel from the sinus node to the ventricles. In this normal sinus rhythm, the PR interval does fall in the normal range.<\/li>\n<li><strong>What is the width of the QRS complex?<\/strong> This represents the contraction of the ventricles (normally 0.06-0.12 sec\/1.5-3 small squares) and the QRS complex is within the normal range here.<\/li>\n<\/ol>\n<h2><span id=\"Atrial_Flutter\" class=\"m-toc-anchor\"><\/span>Atrial Flutter<\/h2>\n<p>\nAtrial flutter occurs when the electrical impulses of the heart take an abnormal path through the atria, usually circulating around the tricuspid valve in the right atrium. The atria discharge between 240 to 400 regular impulses every minute. These atrial contractions produce flutter (F) waves that have a sawtooth appearance.<\/p>\n<p>With such rapid atrial contractions, the AV node slows them down, often with every second or third contraction reaching the ventricle. The ventricles often respond to the impulses at a regular rate, therefore the QRS complexes are usually normal and regular. The number of F waves to QRS complexes is expressed as a ratio. For example, in atrial flutter with an atrial rate of 280, and a ventricular rate, or pulse rate, stuck at 70, it is referred to as 4:1 A-V conduction.<\/p>\n<p>Atrial flutter usually indicates underlying disease and may show symptoms of palpitations, shortness of breath, anxiety, or weakness.<\/p>\n<div class=\"transcriptcallout\">\n<strong>Atrial Flutter<\/strong><\/p>\n<ul style=\"text-align: left; margin-left: 1.5em; margin-bottom: 0.5em;\">\n<li>Electrical impulses circulate around the tricuspid valve<\/li>\n<li>240-400 impulses discharged per minute<\/li>\n<li>Flutter (F) waves have a sawtooth appearance<\/li>\n<li>AV node slows down rapid atrial contractions<\/li>\n<li>QRS complexes normal and regular<\/li>\n<\/ul>\n<\/div>\n<p>\n&nbsp;<\/p>\n<h3><span id=\"Evaluating_Atrial_Flutter\" class=\"m-toc-anchor\"><\/span>Evaluating Atrial Flutter<\/h3>\n<p>\nNow we\u2019ll use the six-step approach to evaluate atrial flutter:<\/p>\n<ol>\n<li style=\"margin-bottom: 10px;\"><strong>What is the heart rate?<\/strong> Counting the R waves (QRS complexes) in six seconds, there are 7, so \\(7\\times 10=\\) a ventricular rate of 70 bpm.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are there P waves present?<\/strong> No, only saw-toothed flutter (F) waves The atrial rate can be figured out by counting the number of F waves in the six seconds and multiplying by 10. There are 28 F waves, so the atrial rate is 280 bpm.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are the P waves regular?<\/strong> There are no P waves, so this doesn\u2019t apply.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are the R waves regular?<\/strong> This is the interval from one R wave to the next. If you use calipers or a paper to mark the beginning of the QRS complex to the beginning of the next QRS complex, you see that the QRS complexes or R waves occur at regular intervals. However, sometimes they can be irregular also.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>How long is the PR interval?<\/strong> Since there are no P waves, it is not measurable.\n<li><strong>What is the width of the QRS complex?<\/strong> They are all normal, falling between 0.06-0.12 sec.<\/li>\n<\/ol>\n<h2><span id=\"Atrial_Fibrillation_(AFib)\" class=\"m-toc-anchor\"><\/span>Atrial Fibrillation (AFib)<\/h2>\n<p>\nInstead of one impulse moving through the heart as it should, many impulses begin in the atria and fight to get through the AV node. The atria depolarize chaotically at rates of 350-600 beats per minute. These extra impulses trying to get through the AV node cause the atria to fibrillate (quiver and twitch) in a fast and disorganized way.<\/p>\n<p>This chaotic electrical activity results in a chaotic waveform between the QRS complexes. The P waves are absent and are replaced by lowercase \u201cf\u201d waves. No P waves mean there are no PR intervals. The rapid electrical activity overwhelming the AV node causes impulses to enter the ventricular conduction system at irregular points without a discernible pattern, resulting in an \u201cirregularly irregular\u201d ventricular rhythm (R waves).<\/p>\n<p>This irregular heart rhythm can cause symptoms such as shortness of breath, exercise intolerance, heart palpitations, or weakness, but some people experience no symptoms at all. However, if left untreated, the side effects can be life-threatening, leading to stroke or heart failure.<\/p>\n<h3><span id=\"Evaluating_Atrial_Fibrillation\" class=\"m-toc-anchor\"><\/span>Evaluating Atrial Fibrillation<\/h3>\n<p>\nNow we\u2019ll use the six-step approach to evaluate atrial fibrillation:<\/p>\n<ol>\n<li style=\"margin-bottom: 10px;\"><strong>What is the heart rate?<\/strong> Counting the R waves (QRS complexes) in 6 seconds, there are 7, so <span style=\"font-size: 90%;\">\\(7&#215;10=\\)<\/span> a ventricular rate of 70 bpm.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are there P waves present?<\/strong> No, only fibrillatory (f) waves The atrial rate is impossible to determine, but is very fast, most certainly &gt;350 bpm.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are the P waves regular?<\/strong> There are no P waves, so this doesn\u2019t apply.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>Are the R waves regular?<\/strong> If you use calipers or a paper to mark the beginning of the QRS complex to the beginning of the next QRS complex, you see that the QRS complexes or R waves occur at irregular intervals.<\/li>\n<li style=\"margin-bottom: 10px;\"><strong>How long is the PR interval?<\/strong> Since there are no P waves, it is not measurable<\/li>\n<li><strong>What is the width of the QRS complex?<\/strong> They are all normal, falling between 0.06-0.12 sec.<\/li>\n<\/ol>\n<p>Both atrial flutter and AFib are common abnormal heart rhythms. They are both types of supraventricular tachycardia, which means a rapid heart beat occurring above the ventricles. In AFib, the heart beats fast and in no regular pattern or rhythm. With atrial flutter, the heart beats fast, but in a regular pattern\u2014the \u201csawtooth\u201d pattern.<\/p>\n<hr>\n<h2><span id=\"Review\" class=\"m-toc-anchor\"><\/span>Review<\/h2>\n<p>\nLet\u2019s do a quick comparison to review.<\/p>\n<p>In atrial flutter, the atrial rate is between 240-400 bpm. In AFib, we are not able to determine the atrial rate. Neither arrhythmia has P waves. Atrial flutter has sawtooth flutter (F) waves and AFib has fibrillatory (f) waves. The R waves in atrial flutter are usually regular, but in AFib they are irregular. Neither arrhythmia has a PR interval, but the QRS width on both is normal.<\/p>\n<table class=\"ATable\" style=\"margin: auto; width: 75%;\">\n<thead>\n<tr style=\"height: 45px;\">\n<th style=\"vertical-align: middle; width: 50%;\">Atrial Flutter<\/th>\n<th style=\"vertical-align: middle; width: 50%;\">Atrial Fibrillation<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Atrial rate 240-400 bpm<\/td>\n<td>Unable to determine atrial rate<\/td>\n<\/tr>\n<tr>\n<td colspan=\"2\">No P waves<\/td>\n<\/tr>\n<tr>\n<td>Sawtooth flutter F waves<\/td>\n<td>Fibrillatory f waves<\/td>\n<\/tr>\n<tr>\n<td>R waves usually regular<\/td>\n<td>R waves irregular<\/td>\n<\/tr>\n<tr>\n<td colspan=\"2\">No PR interval<\/td>\n<\/tr>\n<tr>\n<td colspan=\"2\">QRS width normal<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\n&nbsp;<br \/>\nFor more videos on EKGs, check out our <a class=\"ylist\" href=\"https:\/\/www.youtube.com\/playlist?list=PL0512aSwU39_GpAo5R80kdMCcEttw7t_4\">EKG playlist<\/a>.<\/p>\n<\/div>\n<\/div>\n\n<div class=\"home-buttons\">\n<p><a href=\"https:\/\/www.mometrix.com\/academy\/patient-care\/\">Return to Patient Care Videos<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Return to Patient Care Videos<\/p>\n","protected":false},"author":1,"featured_media":121882,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":{"0":"post-27464","1":"page","2":"type-page","3":"status-publish","4":"has-post-thumbnail","6":"page_category-cardiovascular-videos","7":"page_category-patient-care-videos","8":"page_category-physiological-integrity","9":"page_category-video-pages-for-study-course-sidebar-ad","10":"page_type-video","11":"subject_matter-nursing"},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/pages\/27464","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/comments?post=27464"}],"version-history":[{"count":5,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/pages\/27464\/revisions"}],"predecessor-version":[{"id":280811,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/pages\/27464\/revisions\/280811"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/media\/121882"}],"wp:attachment":[{"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/media?parent=27464"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}