{"id":10781,"date":"2026-06-28T06:46:13","date_gmt":"2026-06-28T06:46:13","guid":{"rendered":"https:\/\/cardiocases.com\/?post_type=ecg_case&#038;p=10781"},"modified":"2026-07-02T11:46:43","modified_gmt":"2026-07-02T11:46:43","slug":"trace-1-6-syncope-left-bundle-branch-block-and-av-block","status":"publish","type":"ecg_case","link":"https:\/\/cardiocases.com\/fr\/ecg_case\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\/","title":{"rendered":"Trace 1.6: Syncope, left bundle branch block and AV block"},"content":{"rendered":"","protected":false},"featured_media":10637,"template":"","ecg_case_type":[250],"language_ecgcase":[258],"class_list":["post-10781","ecg_case","type-ecg_case","status-publish","has-post-thumbnail","hentry","ecg_case_type-atrioventricular-block","language_ecgcase-english"],"acf":{"ecg_case_title":"Trace 1.6: Syncope, left bundle branch block and AV block","patient_description":"87-year-old woman; admitted due to two syncopes;","quiz_question":"Which diagnosis(es) is(are) true for this ECG?","quiz_answer_1":"sinus rhythm","quiz_answer_2":"left atrial enlargement","quiz_answer_3":"right bundle branch block + left anterior fascicular block","quiz_answer_4":"left bundle branch block","quiz_answer_5":"non-specific bundle branch block","correct_answer":["A","B","D"],"ecg_image":10637,"ecg_description":"Sinus rhythm, left atrial enlargement (widened and fragmented P wave); left bundle branch block: QRS width > 120 ms; absence of q wave along with wide and notched R wave in leads I, aVL, V5 and V6 with delayed intrinsicoid deflection > 60 ms; QS and rS pattern in V1 and V2; ST segment depression and negative T wave in leads I, aVL, V5 and V6;","ecg_info_box":"When associated with a bundle branch block, a second-degree AV block Wenckebach type pattern may result from a delayed conduction in the atrioventricular node but should raise suspicion and warrant exploring for a delayed activation on the opposite branch of the blocked branch (trifascicular block). Electrophysiological study may reveal a prolonged HV interval.","commentary_ecg":"-","ecg_info_post_answer":"&nbsp;\r\n\r\n&nbsp;\r\n\r\nDuring an episode of near-syncope\r\n\r\n<img class=\"alignnone wp-image-10398 size-large\" src=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/04\/trace-1-6-ecg2-1024x714.png\" alt=\"\" width=\"800\" height=\"558\" \/>\r\n\r\n<strong>Trace<\/strong>\r\n\r\nLeft bundle branch block; bradycardia associated with a Mobitz 1 second-degree AV block pattern; gradual prolongation of the PR interval followed by blocked P wave (Wenckebach periods);\r\n\r\n&nbsp;\r\n\r\n<strong>Commentary<\/strong>\r\n\r\nThis patient presented with a syncope which resulted in a fall with bleeding scalp wound. The electrocardiogram revealed a characteristic pattern of complete left bundle branch block. During an episode of lightheadedness, the ECG showed a bradycardia in conjunction with a second-degree (Mobitz 1) AV block pattern.\r\n\r\nWhen there is an associated branch block, a second-degree AV block with Wenckebach periodicity may result from a slowing of conduction in the atrioventricular node, but should also raise suspicion and warrant investigation for a delayed activation on the branch opposite to the blocked branch (trifascicular block). The infra-Hisian Wenckebach periods in these instances are associated with a constant AH interval and a gradual prolongation of the HV interval, the blocked P wave being followed by a His potential not conducted to the ventricle.\r\n\r\nThe indications for implantation in the setting of second-degree AV block type 1 are controversial. The causal relationship between conduction disorder and the onset of symptoms is difficult to establish, especially when the symptoms are modest and unspecific. There is a class IIA indication in the European guidelines when a second-degree AV block type 1 is responsible for symptoms or when the conduction disorder is of intra- or infra-Hisian localization (major risk of progression to a complete atrioventricular block) upon electrophysiological study (EPS). This patient underwent an EPS which confirmed the presence of a trifascicular block and underwent pacemaker implantation.\r\n\r\n&nbsp;\r\n\r\n<img class=\"alignnone wp-image-10791 size-large\" src=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/06\/trace-1-6-ecg-en-1024x576.jpg\" alt=\"\" width=\"800\" height=\"450\" \/>"},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.0 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Trace 1.6: Syncope, left bundle branch block and AV block - Cardiocases<\/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:\/\/cardiocases.com\/fr\/ecg_case\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Trace 1.6: Syncope, left bundle branch block and AV block - Cardiocases\" \/>\n<meta property=\"og:url\" content=\"https:\/\/cardiocases.com\/fr\/ecg_case\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\/\" \/>\n<meta property=\"og:site_name\" content=\"Cardiocases\" \/>\n<meta property=\"article:modified_time\" content=\"2026-07-02T11:46:43+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/04\/trace-1-6-ecg.jpeg\" \/>\n\t<meta property=\"og:image:width\" content=\"1645\" \/>\n\t<meta property=\"og:image:height\" content=\"831\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Dur\u00e9e de lecture estim\u00e9e\" \/>\n\t<meta name=\"twitter:data1\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\\\/\",\"url\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\\\/\",\"name\":\"Trace 1.6: Syncope, left bundle branch block and AV block - Cardiocases\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/cardiocases.com\\\/wp-content\\\/uploads\\\/2026\\\/04\\\/trace-1-6-ecg.jpeg\",\"datePublished\":\"2026-06-28T06:46:13+00:00\",\"dateModified\":\"2026-07-02T11:46:43+00:00\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\\\/#breadcrumb\"},\"inLanguage\":\"fr-FR\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\\\/#primaryimage\",\"url\":\"https:\\\/\\\/cardiocases.com\\\/wp-content\\\/uploads\\\/2026\\\/04\\\/trace-1-6-ecg.jpeg\",\"contentUrl\":\"https:\\\/\\\/cardiocases.com\\\/wp-content\\\/uploads\\\/2026\\\/04\\\/trace-1-6-ecg.jpeg\",\"width\":1645,\"height\":831},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-1-6-syncope-left-bundle-branch-block-and-av-block\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/cardiocases.com\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Trace 1.6: Syncope, left bundle branch block and AV block\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/#website\",\"url\":\"https:\\\/\\\/cardiocases.com\\\/\",\"name\":\"Cardiocases\",\"description\":\"Real cardiac device traces, pacemaker &amp; 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