ECG Guru - Instructor Resources - Second-degree AV block with 2:1 conduction https://www.ecgguru.com/ecg/second-degree-av-block-21-conduction en Second-degree AV Block, Mobitz Type II https://www.ecgguru.com/blog/second-degree-av-block-mobitz-type-ii <div class="field field-name-field-blog-image field-type-image field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/blog/second-degree-av-block-mobitz-type-ii"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/1_0.jpg" width="3063" height="1249" alt="" /></a></div><div class="field-item odd"><a href="/blog/second-degree-av-block-mobitz-type-ii"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/2_0.jpg" width="3061" height="1303" alt="" /></a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even" property="content:encoded"><p><span style="font-size: 10px;">We are observing EKG strip 1 in a Holter EKG recording; what can be said about it? There is a sinus rhythm with a normal PQ interval. After 3 sinus beats, a 2:1 AV block develops. When 2:1 AV block occurs, we should not refer to this as Wenckebach (Mobitz I) or Mobitz II, but rather as a high-grade AV block (other forms include: 3:1, 4:1, 5:1, etc.). The 2:1 block can be intranodally localized and behave benignly like a Wenckebach block typically does. However, it could also be infranodally localized with a potentially serious prognosis. Only EKG strip 2 allows us to make a precise diagnosis: here, the criteria for a Mobitz II block are met: sudden and unexpected failure of AV conduction with constant PP intervals (exception: ventriculophasic sinusarhrythmia), and PR intervals. Thus, a pacemaker indication is generally present here, unless there are remediable causes for the AV block. </span></p> <p><span style="font-size: 10px;">In general, it is important to note that the indication for a pacemaker must always be made in the context of all available facts and findings.</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/561/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 Second-degree AV Block, Mobitz Type II 1/5</option><option value="40">Give Second-degree AV Block, Mobitz Type II 2/5</option><option value="60">Give Second-degree AV Block, Mobitz Type II 3/5</option><option value="80">Give Second-degree AV Block, Mobitz Type II 4/5</option><option value="100">Give Second-degree AV Block, Mobitz Type II 5/5</option></select> <div class="description"><div class="fivestar-summary fivestar-summary-average-count"><span class="empty">No votes yet</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-fmBSGO6_PLiE7dcdK3KYjJNcl6ut-KzE4WM1l3S87T4" /> <input type="hidden" name="form_id" value="fivestar_custom_widget" /> </div></form></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%2Fblog%2Fsecond-degree-av-block-mobitz-type-ii&amp;title=Second-degree%20AV%20Block%2C%20Mobitz%20Type%20II"><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(); //--><!]]> </script></span></li> </ul> Wed, 02 Aug 2023 08:35:01 +0000 Dr A Röschl 860 at https://www.ecgguru.com https://www.ecgguru.com/blog/second-degree-av-block-mobitz-type-ii#comments Second-degree AV Block with 2:1 Conduction and Right Bundle Branch Block https://www.ecgguru.com/ecg/second-degree-av-block-21-conduction-and-right-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/second-degree-av-block-21-conduction-and-right-bundle-branch-block"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/RBAVB100_0.jpg" width="1591" height="1207" 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 style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: Verdana, Helvetica, Arial, sans-serif; font-size: 13px; font-stretch: inherit; line-height: 17.7272720336914px; clear: left;">This interesting ECG is a great one for your more advanced students who are ready to discuss the anatomical and physiological differences between the AV blocks, as opposed to just measuring PR intervals. &nbsp;It shows a sinus rhythm with an atrial rate of 72/minute.&nbsp; Second-degree AV block causes every other p wave to be blocked, resulting in a pulse rate of 36 beats per minute.&nbsp; In addition, the ECG shows right bundle branch block, as evidenced by the wide QRS (136 ms), rsR'&nbsp;pattern in V1, and the wide little S wave in Lead I.</p><p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: Verdana, Helvetica, Arial, sans-serif; font-size: 13px; font-stretch: inherit; line-height: 17.7272720336914px; clear: left;"><span style="line-height: 17.7272720336914px;">When second-degree AVB conducts 2:1, it can sometimes be difficult to determine if the block is Type I (occuring above the Bundle of His), or Type II (occuring at or below the Bundle of His).&nbsp; This is because two p waves must be conducted in a row to see the tell-tale progressive prolongation of the PR interval seen in&nbsp;Type I (Wenkebach).</span></p><p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: Verdana, Helvetica, Arial, sans-serif; font-size: 13px; font-stretch: inherit; line-height: 17.7272720336914px; clear: left;">Two&nbsp;clues that this block is Type II are:&nbsp; 1) the presence of right bundle branch block.&nbsp; Type II blocks are sub-Hisian blocks, often in the fascicles, and the right bundle branch block is a fascicle block.&nbsp; Many Type II AV blocks show signs of right bundle branch block; &nbsp; 2) The non-conducted p waves occur well clear of the refractory periods of the preceding beats.&nbsp; In Type I blocks, the QRS is eventually dropped because the&nbsp;p wave occurs in the refractory beat of the preceding QRS. Only one beat is missed.&nbsp; In Type II blocks, p waves that SHOULD have conducted, don't.&nbsp; Sometimes, more than one p wave in a row will be non-conducted.</p><p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: Verdana, Helvetica, Arial, sans-serif; font-size: 13px; font-stretch: inherit; line-height: 17.7272720336914px; clear: left;">Clinically, we would need to be concerned about the location of the block, because supra-Hisian blocks can be transient or even benign, and sub-Hisian blocks are often permanent or progressive. &nbsp;But the most immediate concern, of course, is that the patient's heart rate has been halved, resulting in a bradycardia which is almost certainly symptomatic. &nbsp;Also, we would want to evaluate the patient for coronary artery disease and M.I., as that could be the cause of the AV block. This patient has some minor flattening of the ST segments in Lead III, but the T wave inversion can be explained by the RBBB. &nbsp;Unfortunately, we do not have clinical information on this patient.</p><div>&nbsp;</div></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/561/feed" method="post" id="fivestar-custom-widget--2" 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--4" name="vote" class="form-select"><option value="-">Select rating</option><option value="20">Give Second-degree AV Block with 2:1 Conduction and Right Bundle Branch Block 1/5</option><option value="40">Give Second-degree AV Block with 2:1 Conduction and Right Bundle Branch Block 2/5</option><option value="60">Give Second-degree AV Block with 2:1 Conduction and Right Bundle Branch Block 3/5</option><option value="80" selected="selected">Give Second-degree AV Block with 2:1 Conduction and Right Bundle Branch Block 4/5</option><option value="100">Give Second-degree AV Block with 2:1 Conduction and Right Bundle Branch Block 5/5</option></select> <div class="description"><div class="fivestar-summary fivestar-summary-average-count"><span class="average-rating">Average: <span >3.5</span></span> <span class="total-votes">(<span >4</span> votes)</span></div></div> </div> </div> </div><input class="fivestar-submit form-submit" type="submit" id="edit-fivestar-submit--2" name="op" value="Rate" /><input type="hidden" name="form_build_id" value="form-UaJsBVgTY36mdCi5c8nQn11t6u0xdXswbvGGzusyPYQ" /> <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/av-block" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">AV Block</a></div><div class="field-item odd"><a href="/ecg/21-av-block" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">2:1 AV block</a></div><div class="field-item even"><a href="/ecg/rbbb" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">RBBB</a></div><div class="field-item odd"><a href="/ecg/bundle-branch-block" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Bundle branch block</a></div><div class="field-item even"><a href="/ecg/second-degree-av-block-type-ii" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Second-degree AV block Type II</a></div><div class="field-item odd"><a href="/ecg/right-bundle-branch-block-1" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Right bundle branch block</a></div><div class="field-item even"><a href="/ecg/second-degree-av-block-21-conduction" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Second-degree AV block with 2:1 conduction</a></div></div></div><ul class="links inline"><li class="addtoany first last"><span><span class="a2a_kit a2a_target addtoany_list" id="da2a_2"> <a class="a2a_dd addtoany_share_save" href="https://www.addtoany.com/share#url=https%3A%2F%2Fwww.ecgguru.com%2Fecg%2Fsecond-degree-av-block-21-conduction-and-right-bundle-branch-block&amp;title=Second-degree%20AV%20Block%20with%202%3A1%20Conduction%20and%20Right%20Bundle%20Branch%20Block"><img src="/sites/all/modules/addtoany/images/share_save_256_24.png" width="256" height="24" alt="Share"/></a> </span> </span></li> </ul> Tue, 03 Mar 2015 05:19:11 +0000 Dawn 626 at https://www.ecgguru.com https://www.ecgguru.com/ecg/second-degree-av-block-21-conduction-and-right-bundle-branch-block#comments Second-degree A-V Block, Type II https://www.ecgguru.com/ecg/second-degree-v-block-type-ii <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/second-degree-v-block-type-ii"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/59_M_Hypoglycemia%20Field%20ECG%203%2000%20am%20Edit%202%20to%201%20AVB%20and%20LBBB.jpg" width="1800" height="674" alt="" /></a></div><div class="field-item odd"><a href="/ecg/second-degree-v-block-type-ii"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/59_M_Hypoglycemia%20Rhythm%20strip%203%20am%202%20to%201%20AVB%20shows%20to%20be%20Type%20II%20at%20end%20edit.jpg" width="1800" height="683" 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>Paramedic Erik Testerman has generously donated several excellent teaching ECGs to the Guru, and we will be featuring all of them soon. &nbsp;This week, we show you the ECGs from a 59-year-old man with a blood glucose of 30 mg/dl. &nbsp;He had no complaints . &nbsp;After a bolus of Dextrose 10%, his blood glucose was 105 mg/dl. &nbsp;He gave a past medical history of diabetes mellitus, hypertension, and left bundle branch block. Vitals were reported as normal and stable, except for the slow heart rate.</p><p>The first ECG, taken in the field, show a second-degree AV Block. &nbsp;The conduction ratio is 2:1. &nbsp;That is, there are two P waves for every QRS complex. &nbsp;With this ratio, it is sometimes difficult to determine whether the patient has Type I (usually AV nodal) or Type II (Infranodal) AVB. &nbsp;In order to diagnose Type I AVB (Wenckebach), we need to see TWO P waves in a row conducted, to see the prolongation of the PR interval. &nbsp;It is not correct, however, to call ALL 2:1 AV blocks "Type II". &nbsp;Often, simply taking a longer rhythm strip will expose a period of 3:2 conduction, showing progressive prolongation of the PRI.</p><p>This ECG, however, gives us some clues that it is probably TYPE II. &nbsp;The patient has a <a title="LBBB Criteria" href="http://ecgguru.com/ecg/left-bundle-branch-block-0">left bundle branch block</a>. &nbsp;Type II AVBs are infranodal - that is, they affect the structures below the AV node: &nbsp;the His Bundle and the Bundle Branches. &nbsp;Type II AVBs represent INTERMITTENT TRI-FASCICULAR BLOCK, and that is common in the presence of RBBB &nbsp;and LBBB (a bi-fascicular block). &nbsp;This ECG probably represents an existing LBBB with an intermittent RBBB - When the right bundle is blocked, the patient has a tri-fascicular block, and no conduction to the ventricles.</p><p>Another clue that this is Type II is that the NON-CONDUCTED P waves fall CLEAR of the preceding T waves, meaning that they had ample opportunity to conduct, not being in the absolute refractory period.</p><p>Fortunately, the rhythm strip, taken one minute later, uncovers the diagnosis! &nbsp;The sixth and seventh QRS complexes are conducted with a 3:2 ratio, showing PR intervals that stay the same, proving the rhythm is Type II.&nbsp;</p><p>For this patient, the heart block and resulting bradycardia don't seem to be causing symptoms. &nbsp;But infranodal blocks can easily progress to complete heart block and should be treated with implanted pacemakers. &nbsp;The EMS crew in this case had transcutaneous pacer pads on the patient as a precaution, but he remained well-perfused and with a good BP the whole time.&nbsp;</p><p>&nbsp;</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/561/feed" method="post" id="fivestar-custom-widget--3" 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--6" name="vote" class="form-select"><option value="-">Select rating</option><option value="20">Give Second-degree A-V Block, Type II 1/5</option><option value="40">Give Second-degree A-V Block, Type II 2/5</option><option value="60">Give Second-degree A-V Block, Type II 3/5</option><option value="80">Give Second-degree A-V Block, Type II 4/5</option><option value="100" selected="selected">Give Second-degree A-V Block, Type II 5/5</option></select> <div class="description"><div class="fivestar-summary fivestar-summary-average-count"><span class="average-rating">Average: <span >5</span></span> <span class="total-votes">(<span >3</span> votes)</span></div></div> </div> </div> </div><input class="fivestar-submit form-submit" type="submit" id="edit-fivestar-submit--3" name="op" value="Rate" /><input type="hidden" name="form_build_id" value="form-CFqrOcneWQ-f8zglp0cF8I1isxCAWekPCt96NypolNM" /> <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/21-av-block" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">2:1 AV block</a></div><div class="field-item odd"><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 even"><a href="/ecg/av-block" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">AV Block</a></div><div class="field-item odd"><a href="/ecg/second-degree-av-block-type-ii" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Second-degree AV block Type II</a></div><div class="field-item even"><a href="/ecg/second-degree-av-block-21-conduction" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Second-degree AV block with 2:1 conduction</a></div><div class="field-item odd"><a href="/ecg/rhythm-strip" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Rhythm strip</a></div></div></div><ul class="links inline"><li class="addtoany first last"><span><span class="a2a_kit a2a_target addtoany_list" id="da2a_3"> <a class="a2a_dd addtoany_share_save" href="https://www.addtoany.com/share#url=https%3A%2F%2Fwww.ecgguru.com%2Fecg%2Fsecond-degree-v-block-type-ii&amp;title=Second-degree%20A-V%20Block%2C%20Type%20II%20"><img src="/sites/all/modules/addtoany/images/share_save_256_24.png" width="256" height="24" alt="Share"/></a> </span> </span></li> </ul> Fri, 28 Mar 2014 02:17:38 +0000 Dawn 564 at https://www.ecgguru.com https://www.ecgguru.com/ecg/second-degree-v-block-type-ii#comments