{"id":10822,"date":"2026-06-28T02:35:15","date_gmt":"2026-06-28T02:35:15","guid":{"rendered":"https:\/\/cardiocases.com\/?post_type=ecg_case&#038;p=10822"},"modified":"2026-07-02T11:39:27","modified_gmt":"2026-07-02T11:39:27","slug":"trace-3-2-left-bundle-branch-block-and-syncope","status":"publish","type":"ecg_case","link":"https:\/\/cardiocases.com\/fr\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/","title":{"rendered":"Trace 3.2: Left bundle branch block and syncope"},"content":{"rendered":"","protected":false},"featured_media":9614,"template":"","ecg_case_type":[252],"language_ecgcase":[258],"class_list":["post-10822","ecg_case","type-ecg_case","status-publish","has-post-thumbnail","hentry","ecg_case_type-bundle-branch-block","language_ecgcase-english"],"acf":{"ecg_case_title":"Trace 3.2: Left bundle branch block and syncope","patient_description":"87-year-old woman; admitted after 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":"bloc de branche droit + h\u00e9mibloc ant\u00e9rright bundle branch block + left anterior fascicular blockieur gauche","quiz_answer_4":"left bundle branch block","quiz_answer_5":"non-specific bundle branch block","correct_answer":["A","B","D"],"ecg_image":9614,"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":"The electrocardiographic signs of a left bundle branch block are: a wide QRS, a characteristic pattern in V6 (delayed intrinsicoid deflection, absence of q waves, exclusive positive deflections, frequent ST segment depression), a characteristic pattern in V1 (absence of delayed intrinsicoid deflection, an rS or QS pattern).","commentary_ecg":"This patient presents a characteristic electrocardiographic pattern of left bundle branch block combining:\r\n\r\n1.   A widened QRS complex of 120 ms or more in adults, a QRS greater than 100 ms in children under 8 years of age;\r\n2.   A delayed onset of intrinsicoid deflection greater than 60 ms (ventricular activation time potentially reaching up to 100 ms) in the left precordial leads: this is due to the delayed depolarization of the affected ventricular wall; this is a major and fundamental criterion of left bundle branch block; the intrinsicoid deflection is normal in right precordial leads since the right ventricle is normally activated;\r\n3.   A characteristic QRS pattern in V6: an initial positive deflection is observed, with the direction of the septal depolarization being reversed and propagating from right to left; the septal activation vectors are thus directed to the left precordial leads which record a positive initial deflection; the presence of a q wave in V6 therefore allows to eliminate the diagnosis of a left bundle branch block; the amplitude of the R wave is often increased; indeed, when left ventricular activation is delayed, it no longer encounters opposition on the part of the right ventricular depolarization, accounting for a higher voltage potential; the foot of the R wave is often slurred or sometimes notched and the ensuing ascending branch is relatively fast and followed by a considerable strong slowing at the peak (bifidity or plateau pattern) and a brief descent towards the isoelectric line; absence of a terminal s wave;\r\n4.   A characteristic QRS pattern in V1: wide S wave in conjunction with the delayed occurrence of the left depolarization vectors; the most typical pattern is therefore rS or QS;\r\n5.   A modified ST segment and T wave in V5, V6: a depression of the ST segment and an inverted T wave are frequently found with a possible elevation in V1;\r\n6.   In the frontal leads, the characteristic pattern found in V6 (exclusive positivity followed by a negative and symmetrical T wave with depression) is found in lead I and more often in aVL;\r\n \r\n\r\nQRS axis is variable: it can be normal or deviated to the left. The presence of a left bundle branch block renders the diagnosis of infarction or ventricular hypertrophy difficult.","ecg_info_post_answer":"<img class=\"alignnone wp-image-10825 size-large\" src=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/06\/trace-3-2-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 3.2: Left bundle branch block and syncope - 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-3-2-left-bundle-branch-block-and-syncope\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Trace 3.2: Left bundle branch block and syncope - Cardiocases\" \/>\n<meta property=\"og:url\" content=\"https:\/\/cardiocases.com\/fr\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/\" \/>\n<meta property=\"og:site_name\" content=\"Cardiocases\" \/>\n<meta property=\"article:modified_time\" content=\"2026-07-02T11:39:27+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/03\/trace-3-2-ecg-scaled-e1782933140347.jpeg\" \/>\n\t<meta property=\"og:image:width\" content=\"2560\" \/>\n\t<meta property=\"og:image:height\" content=\"1516\" \/>\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-3-2-left-bundle-branch-block-and-syncope\\\/\",\"url\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-3-2-left-bundle-branch-block-and-syncope\\\/\",\"name\":\"Trace 3.2: Left bundle branch block and syncope - Cardiocases\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-3-2-left-bundle-branch-block-and-syncope\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-3-2-left-bundle-branch-block-and-syncope\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/cardiocases.com\\\/wp-content\\\/uploads\\\/2026\\\/03\\\/trace-3-2-ecg-scaled-e1782933140347.jpeg\",\"datePublished\":\"2026-06-28T02:35:15+00:00\",\"dateModified\":\"2026-07-02T11:39:27+00:00\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-3-2-left-bundle-branch-block-and-syncope\\\/#breadcrumb\"},\"inLanguage\":\"fr-FR\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-3-2-left-bundle-branch-block-and-syncope\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-3-2-left-bundle-branch-block-and-syncope\\\/#primaryimage\",\"url\":\"https:\\\/\\\/cardiocases.com\\\/wp-content\\\/uploads\\\/2026\\\/03\\\/trace-3-2-ecg-scaled-e1782933140347.jpeg\",\"contentUrl\":\"https:\\\/\\\/cardiocases.com\\\/wp-content\\\/uploads\\\/2026\\\/03\\\/trace-3-2-ecg-scaled-e1782933140347.jpeg\",\"width\":2560,\"height\":1516},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/ecg_case\\\/trace-3-2-left-bundle-branch-block-and-syncope\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/cardiocases.com\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Trace 3.2: Left bundle branch block and syncope\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/#website\",\"url\":\"https:\\\/\\\/cardiocases.com\\\/\",\"name\":\"Cardiocases\",\"description\":\"Real cardiac device traces, pacemaker &amp; ICD learning \u2014 built by electrophysiologists\",\"publisher\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/cardiocases.com\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"fr-FR\"},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/#organization\",\"name\":\"Cardiocases\",\"url\":\"https:\\\/\\\/cardiocases.com\\\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\\\/\\\/cardiocases.com\\\/#\\\/schema\\\/logo\\\/image\\\/\",\"url\":\"https:\\\/\\\/cardiocases.com\\\/wp-content\\\/uploads\\\/2025\\\/07\\\/cardiocases_logo.png\",\"contentUrl\":\"https:\\\/\\\/cardiocases.com\\\/wp-content\\\/uploads\\\/2025\\\/07\\\/cardiocases_logo.png\",\"width\":1755,\"height\":499,\"caption\":\"Cardiocases\"},\"image\":{\"@id\":\"https:\\\/\\\/cardiocases.com\\\/#\\\/schema\\\/logo\\\/image\\\/\"},\"sameAs\":[\"https:\\\/\\\/www.linkedin.com\\\/company\\\/cardiocases\\\/\"]}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Trace 3.2: Left bundle branch block and syncope - Cardiocases","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/cardiocases.com\/fr\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/","og_locale":"fr_FR","og_type":"article","og_title":"Trace 3.2: Left bundle branch block and syncope - Cardiocases","og_url":"https:\/\/cardiocases.com\/fr\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/","og_site_name":"Cardiocases","article_modified_time":"2026-07-02T11:39:27+00:00","og_image":[{"width":2560,"height":1516,"url":"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/03\/trace-3-2-ecg-scaled-e1782933140347.jpeg","type":"image\/jpeg"}],"twitter_card":"summary_large_image","twitter_misc":{"Dur\u00e9e de lecture estim\u00e9e":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/cardiocases.com\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/","url":"https:\/\/cardiocases.com\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/","name":"Trace 3.2: Left bundle branch block and syncope - Cardiocases","isPartOf":{"@id":"https:\/\/cardiocases.com\/#website"},"primaryImageOfPage":{"@id":"https:\/\/cardiocases.com\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/#primaryimage"},"image":{"@id":"https:\/\/cardiocases.com\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/#primaryimage"},"thumbnailUrl":"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/03\/trace-3-2-ecg-scaled-e1782933140347.jpeg","datePublished":"2026-06-28T02:35:15+00:00","dateModified":"2026-07-02T11:39:27+00:00","breadcrumb":{"@id":"https:\/\/cardiocases.com\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/#breadcrumb"},"inLanguage":"fr-FR","potentialAction":[{"@type":"ReadAction","target":["https:\/\/cardiocases.com\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/"]}]},{"@type":"ImageObject","inLanguage":"fr-FR","@id":"https:\/\/cardiocases.com\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/#primaryimage","url":"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/03\/trace-3-2-ecg-scaled-e1782933140347.jpeg","contentUrl":"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/03\/trace-3-2-ecg-scaled-e1782933140347.jpeg","width":2560,"height":1516},{"@type":"BreadcrumbList","@id":"https:\/\/cardiocases.com\/ecg_case\/trace-3-2-left-bundle-branch-block-and-syncope\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/cardiocases.com\/"},{"@type":"ListItem","position":2,"name":"Trace 3.2: Left bundle branch block and syncope"}]},{"@type":"WebSite","@id":"https:\/\/cardiocases.com\/#website","url":"https:\/\/cardiocases.com\/","name":"Cardiocases","description":"Real cardiac device traces, pacemaker &amp; ICD learning \u2014 built by electrophysiologists","publisher":{"@id":"https:\/\/cardiocases.com\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/cardiocases.com\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"fr-FR"},{"@type":"Organization","@id":"https:\/\/cardiocases.com\/#organization","name":"Cardiocases","url":"https:\/\/cardiocases.com\/","logo":{"@type":"ImageObject","inLanguage":"fr-FR","@id":"https:\/\/cardiocases.com\/#\/schema\/logo\/image\/","url":"https:\/\/cardiocases.com\/wp-content\/uploads\/2025\/07\/cardiocases_logo.png","contentUrl":"https:\/\/cardiocases.com\/wp-content\/uploads\/2025\/07\/cardiocases_logo.png","width":1755,"height":499,"caption":"Cardiocases"},"image":{"@id":"https:\/\/cardiocases.com\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.linkedin.com\/company\/cardiocases\/"]}]}},"_links":{"self":[{"href":"https:\/\/cardiocases.com\/fr\/wp-json\/wp\/v2\/ecg_case\/10822","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cardiocases.com\/fr\/wp-json\/wp\/v2\/ecg_case"}],"about":[{"href":"https:\/\/cardiocases.com\/fr\/wp-json\/wp\/v2\/types\/ecg_case"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cardiocases.com\/fr\/wp-json\/wp\/v2\/media\/9614"}],"wp:attachment":[{"href":"https:\/\/cardiocases.com\/fr\/wp-json\/wp\/v2\/media?parent=10822"}],"wp:term":[{"taxonomy":"ecg_case_type","embeddable":true,"href":"https:\/\/cardiocases.com\/fr\/wp-json\/wp\/v2\/ecg_case_type?post=10822"},{"taxonomy":"language_ecgcase","embeddable":true,"href":"https:\/\/cardiocases.com\/fr\/wp-json\/wp\/v2\/language_ecgcase?post=10822"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}