ECG Guru - Instructor Resources - SA block Type II https://www.ecgguru.com/ecg/sa-block-type-ii en Atrial Bigeminy Vs Possible Sino-atrial Exit Block https://www.ecgguru.com/ecg/instructors-collection-ecg-week-october-5-2015-sino-atrial-exit-block-0 <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/instructors-collection-ecg-week-october-5-2015-sino-atrial-exit-block-0"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/MR%20115%202ndDeg%20SA%20block%20Type%20II_0.jpg" width="3278" height="2289" alt="" /></a></div><div class="field-item odd"><a href="/ecg/instructors-collection-ecg-week-october-5-2015-sino-atrial-exit-block-0"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/MR%20115%20Laddergram%20jpg.jpg" width="3507" height="2550" 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" align="left">This three-lead rhythm strip is from an 85 year-old-woman for whom we have no other information, unfortunately.&nbsp; It shows an obvious, regular bigeminal pattern.&nbsp; There are many rhythms that can cause bigeminy, with regular, paired beats.&nbsp; So, how do we analyze this rhythm?<span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoNormal" align="left">First, we can see that all the QRS complexes are fairly narrow and look alike in each lead.&nbsp; So, we know this is a supraventricular rhythm.&nbsp; The rhythm “marches out”, with the same spacing between all the paired beats, and exactly one P-QRS missing after each pair.<span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoNormal" align="left">Sino-atrial exit block occurs when the sinus node fires, but the impulse is unable to exit the sinus node. No P wave will occur, but the sinus node continues to fire in a regular rhythm.&nbsp; There are four types of SA block, just as there are four types of AV block.&nbsp; <strong>This ECG meets the criteria for a Second-degree, Type II SA block.</strong><strong style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</strong></p><p class="MsoNormal" align="left"><strong>First-degree SA block</strong> would not be decipherable on the ECG, as we do not see the SA node fire, and therefore cannot measure an interval between the SA node firing and the production of a P wave.<span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoNormal" align="left"><strong>Second-degree SA block, Type I</strong> would have progressively prolonging exit times for the impulse leaving the SA node. &nbsp;<span style="font-size: 13.008px; line-height: 1.538em;">This would produce </span><strong style="font-size: 13.008px; line-height: 1.538em;">progressively shortening R-to-R intervals</strong><span style="font-size: 13.008px; line-height: 1.538em;">, until the pause.</span><span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoNormal" align="left"><strong>Second-degree SA block, Type II</strong> has <strong>regular R-to-R intervals until the pause</strong>, and the pause will equal two or more (usually two) R-to-R intervals.&nbsp;</p><p class="MsoNormal" align="left"><strong style="font-size: 13.008px; line-height: 1.538em;">Third-degree SA block</strong><span style="font-size: 13.008px; line-height: 1.538em;"> produces NO P WAVES, and would have to be diagnosed on electrophysiology studies, as it would usually result in a junctional escape rhythm.</span><span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoNormal" align="left">Differential diagnosis includes many causes of “atrial bigeminy”.&nbsp; When every other beat is a premature atrial contraction (APB or PAC), the pause will be caused by the PAC “re-setting” the sinus node, and will not be a multiple of the R-to-R interval on that strip.&nbsp; We can differentiate this rhythm from the AV blocks because in sinus block, the P wave is missing.&nbsp; In AV block, the P wave is present, but not always conducted.<span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoNormal" align="left">To better illustrate what may be happening in this ECG, we have included a laddergram.&nbsp; If you are not familiar with using laddergrams, please refer to the following links.<span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoNormal" align="left">ECG Guru, <a title="Guru Laddergrams Blog" href="http://ecgguru.com/ecg/laddergram">Are You New To Laddergrams</a>,&nbsp;&nbsp; Dr. Ken Grauer, <a title="Grauer Making Laddergrams" href="http://ecg-interpretation.blogspot.com/2013/06/ecg-interpretation-review-69-pvc-pjc.html">Making A Laddergram</a>.<span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span><span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoNormal" align="left">Clinically, we would want to investigate the possible cause of the SA block or atrial bigeminy, and watch for worsening of any block, which could result in a dangerous bradycardia.</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/611/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 Atrial Bigeminy Vs Possible Sino-atrial Exit Block 1/5</option><option value="40">Give Atrial Bigeminy Vs Possible Sino-atrial Exit Block 2/5</option><option value="60">Give Atrial Bigeminy Vs Possible Sino-atrial Exit Block 3/5</option><option value="80" selected="selected">Give Atrial Bigeminy Vs Possible Sino-atrial Exit Block 4/5</option><option value="100">Give Atrial Bigeminy Vs Possible Sino-atrial Exit 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 >2</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-YghENn72kYGmcAlIE5s2OHyKIudTT1HLZc3HaRjepdU" /> <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/sino-atrial-exit-block" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Sino-atrial exit block</a></div><div class="field-item odd"><a href="/ecg/sa-block" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">SA block</a></div><div class="field-item even"><a href="/ecg/sa-block-type-ii" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">SA block Type II</a></div><div class="field-item odd"><a href="/ecg/bigeminy" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Bigeminy</a></div><div class="field-item even"><a href="/ecg/atrial-bigeminy" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Atrial bigeminy</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%2Finstructors-collection-ecg-week-october-5-2015-sino-atrial-exit-block-0&amp;title=Atrial%20Bigeminy%20Vs%20Possible%20Sino-atrial%20Exit%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(); //--><!]]> </script></span></li> </ul> Mon, 05 Oct 2015 23:26:34 +0000 Dawn 670 at https://www.ecgguru.com https://www.ecgguru.com/ecg/instructors-collection-ecg-week-october-5-2015-sino-atrial-exit-block-0#comments