Advanced ECG Interpretations

  Analyzing an Acute MI “Jones’s Rule” and Primary Repolarization Changes Jerry W. Jones, MD FACEP FAAEM Figure 1 This is another 12-lead ECG randomly selected from my collection. There is a bit of baseline wander, but that’s life! It was recorded on a 68 y/o Hispanic female in the emergency department who was complaining of chest pain. There is no other information about her. First, the absolute basics. We can see by the upright P waves in leads I and II that sinus rhythm is present. The pos/neg biphasic P wave in Lead V1 is also supportive of sinus rhythm. The P wave in Lead V2 is basically isoelectric – but that’s OK, as long as it isn’t inverted or biphasic. There is 1:1 sinoatrial conduction and the P-R intervals are normal and remain the same. The rate is quite variable and may represent a sinus arrhythmia. Also, as we will see in a moment, there is also a good reason for increased parasympathetic influence on the rate. No apparent lethal dysrhythmias and no blocks are not...

  Aberrancy and a Complete LBBB That Isn’t! Jerry W. Jones, MD FACEP FAEM This post is about aberrancy, retrograde P′ waves and disease of the conducting system. This ECG was recorded in 2011, so the patient is an 80 year old female who presented to the emergency room for an unknown complaint. There’s a lot to learn on this 12-lead ECG… First, the patient is in sinus rhythm and therein lies our first problem. We see obvious P waves in the inferior leads (II, III, aVF), but not much in Leads I, aVL or aVR. This tells us that the P wave axis is very vertical: the impulse is traveling almost straight down toward the recording electrode on the left foot – which happens to be the positive pole for Leads II, III and aVF. Leads I and aVL are left-sided and Lead aVR is right-sided. They are seeing little to none of the P wave vector, so that tells us that the vector is directed very vertically and downward. There is no suggestion of a P wave in Lead I, which tells us that the P wave vect...

                   A Closer Look at Right Bundle Branch Block (RBBB) Jerry W. Jones, MD FACEP FAAEM I once wrote an article about “rabbit ears” and RBBB and posted it on my blog ( https://medicusofhouston.com/dr-joness-ecg-blog/) . To this date it has been the most read article I have produced. So, let’s take a closer look at RBBB.  The  right bundle branch courses down the wall of the interventricular septum on the right ventricular side. Its course is superficial at some points, so it is very susceptible to injury by central venous lines or stretching (dilatation) of the right ventricle. The diagram on the left shows both bundle branches (right – yellow, left – red). With the right bundle branch blocked up high (dotted line), the atrial impulse travels down the left bundle branch into the anterior and posterior fascicles. The left ventricle is depolarized normally and at its usual speed. The first portion of the left vent...