ECG Guru - Instructor Resources - Dual AV pathways https://www.ecgguru.com/ecg/dual-av-pathways en Supraventricular Tachycardia With Wenckebach Conduction https://www.ecgguru.com/ecg/supraventricular-tachycardia-wenckebach-conduction <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/supraventricular-tachycardia-wenckebach-conduction"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/Wenckebach%20ST.jpg" width="1800" height="1013" alt="" /></a></div><div class="field-item odd"><a href="/ecg/supraventricular-tachycardia-wenckebach-conduction"><img typeof="foaf:Image" src="https://www.ecgguru.com/sites/default/files/RS%20Laddergram%20cropped.jpg" width="800" height="219" 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"><span style="font-size: 12.0pt; line-height: 107%;">This ECG was obtained from a patient in a walk-in health clinic.&nbsp; We do not have any other information on the patient.&nbsp; We thank Joe Kelly for donating this interesting ECG to the GURU.</span><span style="font-size: 8pt; line-height: 107%;">&nbsp;</span></p><p class="MsoNormal"><strong><span style="font-size: 12.0pt; line-height: 107%;">IRREGULAR RHYTHM &nbsp; &nbsp;</span></strong><span style="font-size: 12pt; line-height: 107%;">If you march out the P waves, you will see that they are regular, at a rate of approximately 130 bpm.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp; </span><span style="font-size: 12pt; line-height: 107%;">But the QRS complexes are not regular, and there are fewer QRS complexes than P waves.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp;</span><span style="font-size: 8pt; line-height: 107%;">&nbsp;</span></p><p class="MsoNormal"><strong><span style="font-size: 12.0pt; line-height: 107%;">WENCKEBACH CONDUCTION &nbsp;&nbsp;</span></strong><span style="font-size: 12pt; line-height: 107%;">Looking closely at the PR intervals, you will notice that they progressively prolong.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp; </span><span style="font-size: 12pt; line-height: 107%;">This “pushes” the QRS complexes progressively toward the right.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp; </span><span style="font-size: 12pt; line-height: 107%;">Eventually, the T wave – and the refractory period – will land on the next P wave.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp; </span><span style="font-size: 12pt; line-height: 107%;">That P wave will be unable to conduct to the wave, and no T wave of course, so the next P wave will conduct with a shorter PR interval.</span></p><p class="MsoNormal"><span style="font-size: 12.0pt; line-height: 107%;">We are including a short rhythm strip from this patient, with conduction marked with a <a href="http://ecgguru.com/blog/are-you-new-laddergrams">laddergram.</a></span><span style="font-size: 8pt; line-height: 107%;">&nbsp;</span></p><p class="MsoNormal"><strong><span style="font-size: 12.0pt; line-height: 107%;">NOT A TYPICAL PRESENTATION &nbsp;&nbsp;</span></strong><span style="font-size: 12pt; line-height: 107%;">If your students have always learned “Second-degree AV block, Type I” or “Wenckebach” on a rhythm generator, they will expect to see a normal sinus rhythm, not sinus or atrial tach.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp; </span><span style="font-size: 12pt; line-height: 107%;">They will also expect to see clearly repeating cycles of progressively prolonging PR intervals, until one P wave is non-conducted, producing a slight pause.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp; </span><span style="font-size: 12pt; line-height: 107%;">They may not recognize the cause of the irregularity in this ECG unless they systematically analyze the P wave rhythm and then the QRS complexes and PR intervals.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp; </span><span style="font-size: 12pt; line-height: 107%;">In this patient, V1 probably has the clearest P waves for analysis, and there is a continuous V1 rhythm strip on the bottom of the page.</span><span style="font-size: 8pt; line-height: 107%;">&nbsp;</span></p><p class="MsoNormal"><span style="font-size: 12.0pt; line-height: 107%;">For those more advanced students, there are some “atypical” aspects to this ECG.&nbsp; You may notice that the FIRST P-QRST in each cycle has a PR interval of about .22 seconds, EXCEPT for the <strong>fourth beat on the 12-Lead ECG</strong>.&nbsp; This one appears to have a very SHORT PRI, but it is more likely that the PR interval was so LONG, the QRS appeared slightly AFTER the next P wave.&nbsp; <strong>What do you think?</strong></span><span style="font-size: 8pt; line-height: 107%;">&nbsp;</span></p><p class="MsoNormal"><strong><span style="font-size: 12.0pt; line-height: 107%;">BOTTOM LINE &nbsp; &nbsp;</span></strong><span style="font-size: 12pt; line-height: 107%;">We are hoping some of our experts, including our Consulting Expert, Dr. Grauer, will add more detailed comments to this ECG.</span><span style="font-size: 12pt; line-height: 107%;">&nbsp; </span><span style="font-size: 12pt; line-height: 107%;">The main points we would like to make on the most basic level are:</span></p><p class="MsoListParagraphCxSpFirst" style="margin-left: 31.5pt; mso-add-space: auto; text-indent: -.25in; mso-list: l0 level1 lfo1;"><!--[if !supportLists]--><span style="font-size: 12.0pt; line-height: 107%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">1)<span style="font-stretch: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><!--[endif]--><span style="font-size: 12.0pt; line-height: 107%;">&nbsp;Real ECG rhythms may vary quite a bit from the basic examples seen on electronic rhythm generators, and in some brief references.</span><span style="font-size: 13.008px; line-height: 1.538em;">&nbsp;</span></p><p class="MsoListParagraphCxSpLast" style="margin-left: 31.5pt; mso-add-space: auto; text-indent: -.25in; mso-list: l0 level1 lfo1;"><!--[if !supportLists]--><span style="font-size: 12.0pt; line-height: 107%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">2)<span style="font-stretch: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><!--[endif]--><span style="font-size: 12.0pt; line-height: 107%;">The “AV block” in this case is not a worrisome condition – it is more an expected lack of conduction due to a P wave landing in a refractory period.&nbsp; This is called “physiological block”.&nbsp; I would be more concerned about why this patient has tachycardia, and the clinical approach would be to evaluate the patient’s heart rate in light of his or her presenting symptoms.&nbsp;</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/642/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 Supraventricular Tachycardia With Wenckebach Conduction 1/5</option><option value="40">Give Supraventricular Tachycardia With Wenckebach Conduction 2/5</option><option value="60">Give Supraventricular Tachycardia With Wenckebach Conduction 3/5</option><option value="80" selected="selected">Give Supraventricular Tachycardia With Wenckebach Conduction 4/5</option><option value="100">Give Supraventricular Tachycardia With Wenckebach Conduction 5/5</option></select> <div class="description"><div class="fivestar-summary fivestar-summary-average-count"><span class="average-rating">Average: <span >3.7</span></span> <span class="total-votes">(<span >6</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-vZyOZN3Qe69wGjN8FuBqcaaxqKGGxOWx7e9AwSyv2t0" /> <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/atrial-tachycardia" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Atrial tachycardia</a></div><div class="field-item odd"><a href="/ecg/wenckebach" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Wenckebach</a></div><div class="field-item even"><a href="/ecg/dual-av-pathways" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Dual AV pathways</a></div><div class="field-item odd"><a href="/ecg/laddergram" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Laddergram</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%2Fsupraventricular-tachycardia-wenckebach-conduction&amp;title=%20Supraventricular%20Tachycardia%20With%20Wenckebach%20Conduction"><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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