ECG Guru - Instructor Resources - Intermittent bundle branch block https://www.ecgguru.com/ecg/intermittent-bundle-branch-block en Rate-related Left Bundle Branch Block https://www.ecgguru.com/ecg/rate-related-left-bundle-branch-block <div class="field field-name-field-ecg field-type-image field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/ecg/rate-related-left-bundle-branch-block"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/LB117%20Rate%20dep%20LBBB%20w%20PAC%20edit%20on%20Guru.jpg" width="2980" height="2429" alt="" /></a></div></div></div><div class="field field-name-field-ecg-interpretation field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p class="MsoNormal"><strong><span style="font-size: 12.0pt; line-height: 107%; color: #00b050;">The patient:</span></strong><span style="font-size: 12.0pt; line-height: 107%; color: #00b050;"><span style="mso-spacerun: yes;">&nbsp; </span></span><span style="font-size: 12.0pt; line-height: 107%;">This ECG is from an 87-year-old man who was transported to the Emergency Department by paramedics. His chief complaint, as reported by caregivers, was lethargy, fever, and a declining mental status.<span style="mso-spacerun: yes;">&nbsp; </span>He appeared tired and slightly confused, and was normotensive.</span></p><p class="MsoNormal"><strong><span style="font-size: 12.0pt; line-height: 107%; color: #00b050;">The ECG:</span></strong><span style="font-size: 12.0pt; line-height: 107%; color: #00b050;"><span style="mso-spacerun: yes;">&nbsp; </span></span><span style="font-size: 12.0pt; line-height: 107%;">There are a rhythm strip with two leads, II and III, and also a standard 12-lead ECG. The <strong>RHYTHM STRIP</strong> shows a tachycardiac rhythm that slows very slightly toward the end.<span style="mso-spacerun: yes;">&nbsp; </span>The rate is around 107 bpm, with an R to R interval of approximately 543 ms in the earlier, regular portion.<span style="mso-spacerun: yes;">&nbsp; </span>There are regular P waves present, all followed by QRS complexes.<span style="mso-spacerun: yes;">&nbsp; </span>Most of the QRS complexes are normal width, but the 2<sup>nd</sup>, 5<sup>th</sup>, and 8<sup>th</sup> are slightly wide at 130 ms, or .13 seconds.</span></p><p class="MsoNormal"><span style="font-size: 12.0pt; line-height: 107%;">These wider QRS complexes represent aberrant conduction with LBBB occurring intermittently.<span style="mso-spacerun: yes;">&nbsp; </span>Aberrant conduction often occurs due to a faster heart rate, but the only clue here is the intermittent conduction disturbance seems to disappear when the rate slows very slightly.<span style="mso-spacerun: yes;">&nbsp; </span>It is hard to determine mechanism of aberrant conduction when we have only a ten-second rhythm strip.</span></p><p class="MsoNormal"><span style="font-size: 12.0pt; line-height: 107%;">The <strong>12-LEAD ECG<span style="mso-spacerun: yes;">&nbsp; </span></strong>has essentially the same rate and rhythm, except all the beats in the first ¾ of the ECG are conducted aberrantly, in a LEFT BUNDLE BRANCH BLOCK pattern.<span style="mso-spacerun: yes;">&nbsp; </span>This indicates that the LBB is refractory at this time.<span style="mso-spacerun: yes;">&nbsp; </span>Beat No. 15 is premature (PAC).<span style="mso-spacerun: yes;">&nbsp; </span>The pause after the PAC allows the left bundle branch to repolarize, conducting one single beat normally.</span></p><p class="MsoNormal"><span style="font-size: 12.0pt; line-height: 107%; color: #00b050;"><strong>Conclusion</strong>: </span><span style="font-size: 12.0pt; line-height: 107%;">The patient was determined to be septic, secondary to a urinary tract infection.<span style="mso-spacerun: yes;">&nbsp; </span>We do not know his outcome.</span></p></div></div></div><div class="field field-name-field-rate-this-content field-type-fivestar field-label-above"><div class="field-label">Rate this content:&nbsp;</div><div class="field-items"><div class="field-item even"><form class="fivestar-widget" action="/taxonomy/term/824/feed" method="post" id="fivestar-custom-widget" accept-charset="UTF-8"><div><div class="clearfix fivestar-average-text fivestar-average-stars fivestar-form-item fivestar-hearts"><div class="form-item form-type-fivestar form-item-vote"> <div class="form-item form-type-select form-item-vote"> <select id="edit-vote--2" name="vote" class="form-select"><option value="-">Select rating</option><option value="20">Give Rate-related Left Bundle Branch Block 1/5</option><option value="40" selected="selected">Give Rate-related Left Bundle Branch Block 2/5</option><option value="60">Give Rate-related Left Bundle Branch Block 3/5</option><option value="80">Give Rate-related Left Bundle Branch Block 4/5</option><option value="100">Give Rate-related Left Bundle Branch Block 5/5</option></select> <div class="description"><div class="fivestar-summary fivestar-summary-average-count"><span class="average-rating">Average: <span >1.7</span></span> <span class="total-votes">(<span >121</span> votes)</span></div></div> </div> </div> </div><input class="fivestar-submit form-submit" type="submit" id="edit-fivestar-submit" name="op" value="Rate" /><input type="hidden" name="form_build_id" value="form--8qOktIFNQNoX64MiD88E92R_x-frFrhbcPoIqI2OmQ" /> <input type="hidden" name="form_id" value="fivestar_custom_widget" /> </div></form></div></div></div><div class="field field-name-field-taxonomy field-type-taxonomy-term-reference field-label-above"><div class="field-label">Related Terms:&nbsp;</div><div class="field-items"><div class="field-item even"><a href="/ecg/left-bundle-branch-block-0" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Left bundle branch block</a></div><div class="field-item odd"><a href="/ecg/rate-related-lbbb" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Rate-related LBBB</a></div><div class="field-item even"><a href="/ecg/intermittent-bundle-branch-block" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Intermittent bundle branch block</a></div><div class="field-item odd"><a href="/ecg/premature-atrial-contraction" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Premature atrial contraction</a></div><div class="field-item even"><a href="/ecg/pac" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">PAC</a></div><div class="field-item odd"><a href="/ecg/aberrant-conduction" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Aberrant conduction</a></div><div class="field-item even"><a href="/ecg/lbbb" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">LBBB</a></div></div></div><ul class="links inline"><li class="addtoany first last"><span><span class="a2a_kit a2a_target addtoany_list" id="da2a_1"> <a class="a2a_dd addtoany_share_save" href="https://www.addtoany.com/share#url=https%3A%2F%2Fwww.ecgguru.com%2Fecg%2Frate-related-left-bundle-branch-block&amp;title=Rate-related%20Left%20Bundle%20Branch%20Block"><img src="/sites/all/modules/addtoany/images/share_save_256_24.png" width="256" height="24" alt="Share"/></a> </span> <script type="text/javascript"> <!--//--><![CDATA[//><!-- if(window.da2a)da2a.script_load(); 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