{"id":21371,"date":"2016-05-26T14:21:34","date_gmt":"2016-05-26T08:51:34","guid":{"rendered":"https:\/\/cardiophile.org\/?p=21371"},"modified":"2016-05-26T14:21:34","modified_gmt":"2016-05-26T08:51:34","slug":"av-sequential-pacing-tracking","status":"publish","type":"post","link":"https:\/\/johnsonfrancis.org\/professional\/av-sequential-pacing-tracking\/","title":{"rendered":"AV sequential pacing (tracking)"},"content":{"rendered":"<h2><span style=\"color: #008000;\">AV sequential pacing (tracking)<\/span><\/h2>\n<p><iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/lSY_ZRCHoEA\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen=\"\"><\/iframe><\/p>\n<figure id=\"attachment_21372\" aria-describedby=\"caption-attachment-21372\" style=\"width: 1000px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-21372 size-full\" src=\"https:\/\/johnsonfrancis.org\/professional\/wp-content\/uploads\/2016\/05\/Pacing-tracking.jpg\" alt=\"Pacing tracking\" width=\"1000\" height=\"473\"><figcaption id=\"caption-attachment-21372\" class=\"wp-caption-text\">AV sequential pacing (tracking)<\/figcaption><\/figure>\n<p>At a glance this will seem to be a simple LBBB (left bundle branch block. But the QRS complexes are negative in V5, V6 unlike in a usual LBBB. It is actually AV sequential pacing (tracking). A close scrutiny will reveal the small pacing spikes just before the QRS complexes. They are small because high frequency pacing spikes get filtered off by the low pass filter of the digital ECG machine. Hence pacing spikes especially the small pacing spikes of bipolar pacing are &#8216;ironed out&#8217; by digital ECG filters. If the low pass filters are removed and an upper frequency limit set at 100 Hz, the pacing spikes can be seen well. In case of modern digital cardiac monitors, there is an option to detect pacing spikes, which if enabled, will enhance the pacing spikes very much so that they are easily visible.<br \/>\nIn this ECG, each P wave is followed by a PR interval terminating in a pacing spike and QRS complex. This shows that the pacemaker ventricular pacing is &#8216;tracking&#8217; the P waves. This requires either an atrial lead as in dual chamber pacing or an atrial sensing electrode as in the case of a single lead VDD pacemaker.<br \/>\nThe discordance between the QRS patterns in lead I, aVL vs V5, V6 should make one suspect a pacemaker rhythm and not a simple LBBB pattern. In simple LBBB pattern, there is concordance between the lateral limb leads and chest leads.<br \/>\nLeft axis deviation (negative QRS complexes in inferior leads) indicates pacing from the right ventricular apex so that ventricular activation proceeds from below upwards, away from the inferior leads.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>AV sequential pacing (tracking) At a glance this will seem to be a simple LBBB (left bundle branch block. But the QRS complexes are negative in V5, V6 unlike in a usual LBBB. It is actually AV sequential pacing (tracking). A close scrutiny will reveal the small pacing spikes just before the QRS complexes. They [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":21372,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","footnotes":""},"categories":[6,7],"tags":[],"class_list":["post-21371","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ecg-electrophysiology","category-ecg-library"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>AV sequential pacing (tracking) - All About Cardiovascular System and Disorders<\/title>\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\/av-sequential-pacing-tracking\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"AV sequential pacing (tracking) - All About Cardiovascular System and Disorders\" \/>\n<meta property=\"og:description\" content=\"AV sequential pacing (tracking) At a glance this will seem to be a simple LBBB (left bundle branch block. But the QRS complexes are negative in V5, V6 unlike in a usual LBBB. It is actually AV sequential pacing (tracking). A close scrutiny will reveal the small pacing spikes just before the QRS complexes. They [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/johnsonfrancis.org\/professional\/av-sequential-pacing-tracking\/\" \/>\n<meta property=\"og:site_name\" content=\"All About Cardiovascular System and Disorders\" \/>\n<meta property=\"article:published_time\" content=\"2016-05-26T08:51:34+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/johnsonfrancis.org\/professional\/wp-content\/uploads\/2016\/05\/Pacing-tracking-1.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1000\" \/>\n\t<meta property=\"og:image:height\" content=\"473\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Johnson Francis\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Johnson Francis\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/av-sequential-pacing-tracking\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/av-sequential-pacing-tracking\\\/\"},\"author\":{\"name\":\"Johnson Francis\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/#\\\/schema\\\/person\\\/5441d907049b914770f4bd98fb57feec\"},\"headline\":\"AV sequential pacing (tracking)\",\"datePublished\":\"2016-05-26T08:51:34+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/av-sequential-pacing-tracking\\\/\"},\"wordCount\":289,\"publisher\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/#\\\/schema\\\/person\\\/5441d907049b914770f4bd98fb57feec\"},\"image\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/av-sequential-pacing-tracking\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/wp-content\\\/uploads\\\/2016\\\/05\\\/Pacing-tracking-1.jpg\",\"articleSection\":[\"ECG \\\/ Electrophysiology\",\"ECG Library\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/av-sequential-pacing-tracking\\\/\",\"url\":\"https:\\\/\\\/johnsonfrancis.org\\\/professional\\\/av-sequential-pacing-tracking\\\/\",\"name\":\"AV sequential pacing (tracking) - 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