This ECG is from a 66-year-old woman who called 911 for a complaint of chest pain for the past four hours.
Left bundle branch block
This ECG was taken from an unknown patient. It shows sinus tachycardia with left bundle branch block. The ECG criteria for left bundle branch block are:
* Wide QRS (.12 seconds or greater)
* Negative QRS deflection in V1
* Positive QRS in Leads I and V6
* Supraventricular rhythm
Just like other subjects we are taught in school, ECG interpretation is usually taught in a very basic, simplistic way. As we add to our knowledge, we are able to determine the mechanisms of more complex rhythms.
This 92-year-old patient was diagnosed with left bundle branch block on ECG, and left ventricular hypertrophy on echocardiogram. The two conditions are very often seen together, in fact, a majority of LBBB patients have LVH. Since the two conditions can have similar ECG changes, it is difficult from the ECG alone to determine the presence of LVH when LBBB is present. If the ECG criteria for LVH are present, it can be assumed that LVH is present, even in the presence of LBBB. For determining LVH by ECG criteria, the Sokolov-Lyon criteria are commonly used (
A paramedic crew responded to the office of a local physician. A 61-year-old male presented with a one-week history of chest pain and shortness of breath.
This ECG shows a “classic” left bundle branch block pattern.
The ECG criteria for left bundle branch block are:
This ECG offers several teaching opportunities. First, it is an example of left bundle branch block (LBBB). It was obtained from a 53-year-old man who was undergoing a cardiac cath for chest pain. Unfortunately, we do not have access to his past medical history or the results of his cath. The ECG criteria for a diagnosis of LBBB are: 1) wide QRS complex; 2) supraventricular rhythm; 3) negative QRS in V1 and positive QRS in V6 and Lead I. This ECG shows normal sinus rhythm at a rate of 88 bpm and a wide QRS at 158 ms (.158 seconds).
This is a good example of sinus rhythm with left bundle branch block. There is some irregularity due to a PAC at the beginning. The QRS is wide at 144 ms (.14 seconds). There is also first-degree AV block, with a prolonged PR interval of 228 ms. The criteria for diagnosis of left BBB are: wide QRS, supraventricular rhythm, and a negatively-deflected QRS in V1 with a positive QRS in Leads I and V6.
This ECG, kindly donated by Dr. Ahmed from India, is from a 70-year-old man shows a sinus rhythm at 80 bpm with left bundle branch block (LBBB), left atrial enlargement (LAE), and a premature ventricular contraction (PVC). The ECG criteria for LBBB is: 1) Wide QRS - greater than or equal to .12 seconds; 2) Supraventricular rhythm; 3) QRS that is negative in V1 and positive in Leads I and V6. In leads with a positive QRS, we will see some ST depression, and in leads with a negative QRS, some ST elevation.
This is a good example of atrial fibrillation with left bundle branch block. You get two ECGs with this one, because the patient presented to EMS with a fast heart rate, and the rate was slowed with the drug diltiazem. We do not have any other patient information, unfortunately.
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