EKG of the Week 2019 3-17

This EKG comes courtesy of Dr. Podlog, Dr. Zhi, and Dr. S. Hassan.


An 83 year old female presented to the emergency department complaining of dizziness and sob on exertion for two days. Her first EKG is below (EKG A):

2019 3-17a.jpg

She later had a second EKG (EKG B):

2019 3-17b.jpg


1.    What does EKG A demonstrate?

2.    What does EKGB demonstrate?

3.    How would you manage this patient?


EKG A shows a 2:1 AV block with a ventricular rate of 40.

EKG B shows a 3rd degree AV block.

The patient should have a pacemaker placed.


The patient presented with dizziness and SOB and was found to be bradycardic. The EKG helps elucidate the type of bradycardia.

EKG a shows bradycardia with the presence of P waves but some dropped P waves. This can occur in 2nd degree or 3rd degree AV block. On EKG A, it appears that some P waves are followed by QRS complexes and others are not. This is consistent with 2nd degree AV block. Every 2nd P wave is dropped, so we can not tell if it is 2nd degree type I or 2nd degree type II.

However, on the repeat EKG, there appears to be no relationship between the P waves and the QRS complexes. The R-R intervals are regular and the PR intervals are irregular. This is consistent with 3rd degree AV block.

Patients with 2nd degree AV block can progress to 3rd degree AV block. Close monitoring is essential. Also, running a loner rhythm strip or frequently repeating the EKG can be helpful to allow you to identify higher grade AV block.

Patients with symptomatic 3rd degree AV block require pacing. Prehospital, these patients should be treated with transcutaneous pacing. In the hospital, a transvenous pacemaker should be placed.

Our patient had a transvenous pacemaker placed. EKG C is the repeat EKG after the pacemaker:

2019 3-17c.jpg

The following algorithm is helpful in diagnosing bradycardias on EKG:

Bradycardia algorithm.jpg

EKG of the Week 2018 4-15

This EKG comes courtesy of Dr. Ross Hardy.

A 91 y/o female presents with chest pain. Vital signs: Pulse 35, BP 80/50. The EKG is below:

2018 4-15.png

1.       What findings does the EKG demonstrate?

2.       What is the rhythm?

3.       What is the appropriate management for this patient?



The EKG demonstrates ST elevations in leads II, III and AVF with reciprocal depressions in V2-V6, I and aVL. This is consistent with an inferior wall (or inferoposterior) STEMI.

The rhythm is sinus with a 2nd degree 2:1 AV block.

The MI should initially be treated with antiplatelet drugs (aspirin, clopidogrel/prasugrel). The bradycardia with AV block should be treated with a pacemaker, as the patient is hypotensive. Initially, a transcutaneous pacer should be placed followed by a transvenous pacer. Once appropriate capture is obtained and the heart rate normalizes, the patient should go to the cath lab for emergent PCI.


ST elevations are a sign of acute MI. When you identify both ST depressions and ST elevations on the same EKG, that represents an acute MI in the area of the ST elevations. The ST depressions in that case are only reciprocal changes. Leads II, III and aVF look at the inferior wall of the heart.

Inferior wall MI’s can be associated with bradycardia and AV block. This EKG demonstrates bradycardia with dropped P waves. Some of the P waves are conducted through and some are not (best seen in lead V1). That is characteristic of 2nd degree AV block. Differentiating 2nd degree AV block from 3rd degree AV block can sometimes be difficult, as in this EKG. The following algorithm may be helpful. In this EKG, the RR intervals are regular and the PR intervals are regular. So, we are dealing with 2nd degree AV block.

Algorithm 2nd degree vs 3rd degree AV block (1).jpg

2nd degree AV block comes in two types – type I (AKA Mobitz I, Wenckebach) and type II (AKA Mobitz II). In type I, the PR intervals progressively lengthen followed by a dropped P wave. Then the PR interval shortens again and the cycle repeats. In type II, all PR intervals are the same and there are some dropped P Waves. To differentiate 2nd degree type I from type II, you must see two consecutive beats where the sinus impulse conducts through. This allows you to determine if the PR interval is progressing (type I) or not (type II). In our EKG, every second sinus beat is dropped (best seen in lead V1). So, you do not see two consecutive sinus beats conducting through. This prevents you from differentiating 2nd degree type I from 2nd degree type II. This EKG pattern is referred to as a 2:1 AV block (every second beat is blocked by the AV node). In general, in 2:1 AV block, the presence of a prolonged PR interval makes type I block more likely, whereas the presence of wide QRS complexes makes type II block more likely. However, this is not entirely reliable.

When faced with a 2:1 AV block, running a long rhythm strip may allow you to see two consecutive conducted beats. You can then measure consecutive PR intervals to see if they are prolonging (type I) or the same (type II).


EKG of the Week 2017 1-22

This EKG comes courtesy of Dr. Adamakos.

An 85 year old female presents to the ED complaining of gradual onset SOB. No chest pain and no syncope.

V/S: P 40, R 18, BP 118/74.

She is awake and alert with a normal mental status.

Her EKG is below:

1.    What is the rhythm?

2.    How would you manage this patient?




The rhythm is 2:1 AV block.

Our patient is stable so no emergent intervention is necessary. Atropine can be given but may not work in high grade AV block. Check for causes of the bradycardia including potassium level and medications.


The EKG shows a bradycardia at a ventricular rate of ~38. P waves are present but there are also dropped P waves. The dropped P waves are indicated by arrows on the  EKG below:

Dropped P waves can be caused by 3 things:

1.    Non-conducted PAC’s

2.    2nd degree AV block

3.    3rd degree AV block

To differentiate these causes, first look to see if the dropped P wave comes on time or earlier than expected. If it comes early, it is a non-conducted PAC.

If the P wave comes on time, the cause can be 2nd degree AV block or 3rd degree AV block. Use the algorithm below to differentiate 2nd degree block from 3rd degree block:

Since on this EKG the RR interval are regular and the PR intervals are regular, we are dealing with a 2nd degree AV block. Now we must differentiate 2nd degree type I from type II:

However, on this EKG, we do not have any two consecutive PR intervals. This is because every second P wave is dropped. So, we can not say for certain whether this is type I or type II. This is called 2:1 AV block. For every two P waves there is one QRS complex.

Incidentally, on this EKG, the QT interval is also prolonged.

This patient was admitted to the hospital and had a permanent pacemaker placed.

Use the following algorithm to diagnose bradycardias on EKG: