{"id":10208,"date":"2026-04-03T13:54:58","date_gmt":"2026-04-03T13:54:58","guid":{"rendered":"https:\/\/cardiocases.com\/?post_type=ecg_case&#038;p=10208"},"modified":"2026-04-09T10:20:19","modified_gmt":"2026-04-09T10:20:19","slug":"trace-7-6-tachycardie-orthodromique-et-bloc-gauche-ralentisseur","status":"publish","type":"ecg_case","link":"https:\/\/cardiocases.com\/fr\/ecg_case\/trace-7-6-tachycardie-orthodromique-et-bloc-gauche-ralentisseur\/","title":{"rendered":"Trac\u00e9 7.6: Tachycardie orthodromique et bloc gauche ralentisseur"},"content":{"rendered":"","protected":false},"featured_media":10207,"template":"","ecg_case_type":[256],"language_ecgcase":[259],"class_list":["post-10208","ecg_case","type-ecg_case","status-publish","has-post-thumbnail","hentry","ecg_case_type-junctional-tachycardia","language_ecgcase-french"],"acf":{"ecg_case_title":"Trac\u00e9 7.6: Tachycardie orthodromique et bloc gauche ralentisseur","patient_description":"Homme de 54 ans avec syndrome m\u00e9tabolique trait\u00e9 par fl\u00e9ca\u00efnide et b\u00e9tabloquant; palpi\u00ad tations; premier trac\u00e9 enregistr\u00e9 lors d\u2019un \u00e9pisode de palpitations","quiz_question":"Quel(s) est(sont) le(s) diagnostic(s) probable(s) sur cet ECG?","quiz_answer_1":"tachycardie sinusale","quiz_answer_2":"r\u00e9entr\u00e9e intranodale typique","quiz_answer_3":"tachycardie orthodromique sur voie accessoire","quiz_answer_4":"tachycardie antidromique sur voie accessoire","quiz_answer_5":"flutter atrial commun","correct_answer":["C"],"ecg_image":10207,"ecg_description":"Tachycardie \u00e0 QRS fins avec probable relation 1\/1 entre oreillettes et ventricules; intervalles RR fixes \u00e0 300 ms (200 bpm); activit\u00e9 atriale visualisable au niveau du sommet de l\u2019onde T; elle parait n\u00e9gative dans les d\u00e9rivations inf\u00e9rieures et en DI; aspect compatible avec une tachycardie orthodromique sur voie accessoire lat\u00e9rale gauche; ","ecg_info_box":"Lors d\u2019une tachycardie 1\/1, la survenue d\u2019un bloc de branche qui ralentit le cycle de la tachycardie est en faveur d\u2019une tachycardie sur voie accessoire du c\u00f4t\u00e9 de la branche dont le bloc est ralentisseur (bloc de branche gauche ralentisseur en faveur d\u2019une voie accessoire gauche).","commentary_ecg":"-","ecg_info_post_answer":"&nbsp;\r\n\r\n<img class=\"alignnone wp-image-10461 size-large\" src=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/04\/trace-7-6-ecg2-1024x706.png\" alt=\"\" width=\"800\" height=\"552\" \/>\r\n\r\n<strong>Description trac\u00e9<\/strong>\r\n\r\nTrac\u00e9 enregistr\u00e9 quelques minutes apr\u00e8s le premier; tachycardie 1\/1 entre oreillettes et ventricules avec QRS large (aspect de bloc de branche droit); cycles RR identiques au premier trac\u00e9 (300 ms);\r\n\r\n&nbsp;\r\n\r\n<img class=\"alignnone wp-image-10462 size-large\" src=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/04\/trace-7-6-ecg3-1024x544.png\" alt=\"\" width=\"800\" height=\"425\" \/>\r\n\r\n<strong>Description trac\u00e9<\/strong>\r\n\r\nTrac\u00e9 enregistr\u00e9 quelques minutes apr\u00e8s le premier; tachycardie 1\/1 entre oreillettes et ventricules avec QRS large (aspect de bloc de branche gauche); cycles RR un peu plus lent que sur le trac\u00e9 pr\u00e9c\u00e9dent (330 ms);\r\n\r\n&nbsp;\r\n\r\n<img class=\"alignnone wp-image-10463 size-large\" src=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/04\/trace-7-6-ecg4-1024x793.png\" alt=\"\" width=\"800\" height=\"620\" \/>\r\n\r\n<strong>Description trac\u00e9<\/strong>\r\n\r\nEnregistrement d\u2019un d\u00e9marrage d\u2019une tachycardie sur une extrasystole atriale; aspect de bloc de branche gauche;\r\n\r\n&nbsp;\r\n\r\n<strong>Commentaires<\/strong>\r\n\r\nCe patient pr\u00e9sentait des \u00e9pisodes r\u00e9p\u00e9t\u00e9s de tachycardie orthodromique sur voie accessoire lat\u00e9rale gauche cach\u00e9e. Diff\u00e9rents \u00e9l\u00e9ments permettent d\u2019arriver \u00e0 ce diagnostic: 1) la voie accessoire n\u2019\u00e9tait pas identifiable sur l\u2019\u00e9lectrocardiogramme en rythme sinusal; 2) ce patient pr\u00e9sentait diff\u00e9rents \u00e9pisodes de tachycardie r\u00e9ciproque avec les 2 types d\u2019aberration de conduction (bloc de branche droit ou bloc de branche gauche fonctionnel). Il est relativement fr\u00e9quent qu\u2019au d\u00e9but d\u2019une tachycardie apparaisse pendant quelques complexes une aberration de conduction qui disparait ensuite (adaptation des p\u00e9riodes r\u00e9fractaires de la branche boqu\u00e9e ou disparition de la conduction r\u00e9trograde cach\u00e9e de branche en branche entretenant le bloc de branche). Si la disparition de ce bloc de branche entraine une acc\u00e9l\u00e9ration de la tachycardie, cela signe l\u2019existence d\u2019un faisceau de Kent du c\u00f4t\u00e9 de la branche dont le bloc est ralentisseur. Chez ce patient, le bloc de branche droit ne modifiait pas la fr\u00e9quence de la tachycardie (cycles RR identiques) au contraire du bloc de branche gauche qui allongeait les cycles RR de 30 ms environ. L\u2019allongement du cycle de la tachycardie est secondaire \u00e0 l\u2019allongement de la longueur du circuit dans sa portion ventriculaire (d\u00e9polarisation ventriculaire ralentie en rapport \u00e0 la conduction musculaire caract\u00e9ristique d\u2019un bloc de branche). L\u2019allongement des cycles RR est souvent net quand la voie accessoire est de topographie lat\u00e9rale, il est moindre quand elle est septale. Il est \u00e0 noter toutefois que l\u2019allongement du d\u00e9lai ventriculo-atrial peut \u00eatre compens\u00e9 par une r\u00e9duction du temps de conduction nodale (AH) favoris\u00e9e par la survenue de ce d\u00e9lai. Le r\u00e9sultat final est donc une diminution de la fr\u00e9quence de la tachycardie, moins importante que celle entrain\u00e9e par la modification du temps de conduction ventriculo-atriale; 3) le diagnostic de faisceau de Kent lat\u00e9ral gauche est confort\u00e9 par l\u2019existence d\u2019une onde P\u2019 n\u00e9gative en DI et aVL. En effet, durant la tachycardie, une onde P\u2019 n\u00e9gative en DI traduit l\u2019excitation de l\u2019oreillette \u00e0 partir d\u2019une connexion lat\u00e9rale gauche. La d\u00e9flexion auriculaire est n\u00e9gative car la paroi auriculaire lat\u00e9rale gauche est d\u00e9polaris\u00e9e avant le septum, l\u2019oreillette gauche avant la droite, le vecteur d\u2019activation auriculaire se dirigeant en bas et \u00e0 droite.\r\n\r\nL\u2019analyse minutieuse de l\u2019\u00e9lectrocardiogramme de surface permet de sugg\u00e9rer lalocalisation de la voie accessoire et ainsi d\u2019orienter la proc\u00e9dure d\u2019ablation.\r\n\r\n&nbsp;\r\n\r\n<img class=\"alignnone wp-image-10465 size-large\" src=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/04\/trace-7-6-ecg5-1-1024x793.png\" alt=\"\" width=\"800\" height=\"620\" \/>\r\n\r\n<strong>Description trac\u00e9<\/strong>\r\n\r\nEnregistrement d\u2019un arr\u00eat de la tachycardie; aspect de bloc de branche gauche puis acc\u00e9l\u00e9ration du rythme contemporain de l\u2019affinement du QRS puis r\u00e9duction;\r\n\r\n&nbsp;\r\n\r\n<img class=\"alignnone wp-image-10352 size-large\" src=\"https:\/\/cardiocases.com\/wp-content\/uploads\/2026\/04\/page-366-1024x471.png\" alt=\"\" width=\"800\" height=\"368\" \/>"},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.8 - 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