ECG Guru - Instructor Resources - Repolarization abnormalities https://www.ecgguru.com/ecg/repolarization-abnormalities en Ask the Expert https://www.ecgguru.com/expert-review/ask-expert-11 <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 class="MsoNormal"><strong><span style="font-size: 16.0pt; line-height: 107%; font-family: 'Times New Roman',serif;">Question:</span></strong></p><p class="MsoNormal"><strong><span style="font-size: 14.0pt; line-height: 107%; color: #00b050;">&nbsp;</span></strong></p><p class="MsoNormal"><strong><span style="font-size: 14.0pt; line-height: 107%; color: #00b050;">Dr. Jones, </span></strong></p><p class="MsoNormal"><strong><span style="font-size: 14.0pt; line-height: 107%; color: #00b050;">I am confused about the repolarization abnormalities that occur in conditions other than acute M.I. (Bundle branch block and hypertrophy, for example). I have been taught that the repolarization abnormalities should point opposite the MAIN part of the QRS, but also I have been told that they should point opposite the TERMINAL deflection of the QRS.&nbsp; Which is right?</span></strong></p><p class="MsoNormal"><strong><span style="font-size: 14.0pt; line-height: 107%; color: #00b050;">&nbsp;</span></strong></p><p class="MsoNormal" style="line-height: 15pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><strong><span style="font-size: 12pt; font-family: 'Lucida Sans Unicode', sans-serif; border-width: 1pt; border-style: none; border-color: windowtext; padding: 0in;">Today’s expert is Dr. Jerry W. Jones, MD, FACEP, FAAEM</span></strong></p><p class="MsoNormal" style="line-height: 15pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-size: 9pt; font-family: Verdana, sans-serif; border-width: 1pt; border-style: none; border-color: windowtext; padding: 0in;">Jerry W. Jones, MD FACEP FAAEM is a diplomate of the American Board of Emergency Medicine who has practiced internal medicine and emergency medicine for 35 years. Dr. Jones has been on the teaching faculties of the University of Oklahoma and The University of Texas Medical Branch in Galveston. He is a published author who has also been featured in&nbsp;</span><span style="font-family: Verdana, sans-serif; font-size: 9pt;">the New York Times and the Annals of Emergency Medicine for his work in the developing field of telemedicine. He is also a Fellow of the American College of Emergency Physicians and a Fellow of the American Academy of Emergency Medicine and, in addition, a member of the European Society of Emergency Medicine.&nbsp;</span><span style="font-size: 9pt; font-family: Verdana, sans-serif; border-width: 1pt; border-style: none; border-color: windowtext; padding: 0in;">Dr. Jones is the CEO of<a title="Medicus of Houston Website" href="http://www.medicusofhouston.com/"><span style="font-family: 'inherit',serif; color: #0062a0;">&nbsp;Medicus of Houston</span></a>&nbsp;and the principal instructor for the Advanced ECG Interpretation Boot Camp and the Advanced Dysrhythmia Boot Camp.</span><span style="font-size: 10pt; font-family: 'Lucida Sans Unicode', sans-serif; border-width: 1pt; border-style: none; border-color: windowtext; padding: 0in;">&nbsp;</span></p><p class="MsoNormal" style="margin-bottom: 15pt; line-height: normal; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-size: 10pt; font-family: Verdana, sans-serif;">&nbsp;<img src="/sites/default/files/headshot_0.jpg" width="96" height="100" /></span></p><p class="MsoNormal"><strong><span style="font-size: 16.0pt; line-height: 107%; font-family: 'Times New Roman',serif;">Answer:</span></strong></p><p>&nbsp;</p><p><img src="/sites/default/files/Repol%20Abn%20Illustration%20jpg_0.jpg" width="879" height="373" />&nbsp;</p><p class="MsoNormal" style="margin-bottom: 8.0pt;"><strong><span style="font-size: 14.0pt; line-height: 107%;">Which Direction Should the Repolarization Abnormality Point?</span></strong></p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">OK. You've got an abnormal QRS complex followed by a repolarization abnormality (RA). Which direction should the repolarization abnormality point? As a young resident, I was taught that the RA should point in the direction <em>opposite the terminal deflection of the QRS complex</em>. But years later, I see other physicians stating that the repolarization abnormality should point opposite <em>the main deflection of the QRS complex</em>. Which is correct?</span></p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">The answer is <em>both are correct</em>. Why? How?</span></p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">The reason is that <strong><em>the repolarization abnormality is connected to the <span style="text-decoration: underline;">ventricle in which the problem is located</span> - not the QRS complex itself</em></strong>. To better understand this, let's look at some of the major causes of repolarization abnormalities (you can find examples in the illustration at the top of this page):</span></p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Right Bundle Branch Block (RBBB)</span></strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> - When you look at the QRS complex in V1, you see an R and an R'. The R represents <em>left</em> ventricular activation while the R' represents <em>right</em> ventricular activation. So,<em> the problem lies in the right ventricle represented by the R'</em>. The repolarization abnormality reflects the problem in the RV so it should be opposite the R' which is always the last deflection in V1 in the presence of RBBB. Therefore, <em>in cases of RBBB, the repolarization abnormality is always opposite the <strong>terminal deflection</strong></em> of the QRS.</span></p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Left Bundle Branch Block (LBBB)</span></strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> - When you look at the QRS complex from V6 which has a LBBB, we see a relatively tall, upright monophasic QRS complex. Part of that QRS represents right ventricular depolarization and part represents left ventricular depolarization. But how much of which? We don't know, but all we need to know is that this is a monophasic complex and it is upright. Therefore, since the repolarization abnormality reflects the problem in the left ventricle, and the LV is represented <em>somewhere</em> <em>in that monophasic R</em>, the repolarization abnormality should be opposite the main deflection. Therefore, <em>in cases of LBBB, the repolarization abnormality is always opposite the <strong>main deflection</strong></em> of the QRS.</span></p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Left Ventricular Hypertrophy (LVH)</span></strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> - When you look at the QRS complexes from V5 and V6, we see a relatively tall, upright monophasic QRS complex. Part of that QRS represents right ventricular depolarization and part represents left ventricular depolarization. But how much of which? Again, we don't know, but all we need to know is that this is a monophasic complex and it is upright. Therefore, since the repolarization abnormality reflects the problem in the left ventricle, and the LV is represented somewhere in that monophasic R, the repolarization abnormality should be opposite the main deflection. Therefore, <em>in cases of LVH, the repolarization abnormality is always opposite the <strong>main deflection</strong></em> of the QRS.</span></p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Right Ventricular Hypertrophy (RVH)</span></strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> - The same concept discussed regarding LVH applies in cases of RVH. Therefore, <em>in cases of RVH, the repolarization abnormality is always opposite the <strong>main deflection</strong></em> of the QRS.</span></p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Ventricular Pre-excitation</span></strong><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> - Most people reading ECGs don't realize that ventricular pre-excitation can also produce a repolarization abnormality. Just as repolarization abnormalities are not always present in cases of LVH and RVH, they are not always present in cases of ventricular pre-excitation, either. However, the repolarization abnormality IS present in some cases. The RA is connected to the ventricle containing the accessory pathway, but <em>don't worry: you don't have to determine which ventricle that is</em>. If a repolarization abnormality is present in a lead, it should be negative if the delta wave is positive and vice versa. Therefore, <em>the repolarization abnormality points<strong> opposite to the direction of the delta wave</strong></em>.</span></p><p>&nbsp;</p><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; text-align: justify; line-height: normal;"><span style="font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">So, the question really isn't whether the repolarization abnormality should be opposite the <em>terminal</em> or the <em>main</em> deflection of the QRS. <strong><em>It should be opposite the deflection that represents the involved ventricle</em></strong>.</span></p></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/repolarization-abnormalities" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Repolarization abnormalities</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%2Fexpert-review%2Fask-expert-11&amp;title=Ask%20the%20Expert"><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> Thu, 27 Oct 2016 21:33:15 +0000 Dawn 714 at https://www.ecgguru.com https://www.ecgguru.com/expert-review/ask-expert-11#comments