ECG Guru - Instructor Resources

A gathering place for instructors of ECG and cardiac topics.


Subscribe to me on YouTube

Long PR interval

Non-Sustained Ventricular Tachycardia


This ECG was obtained from a 45-year-old man who was experiencing palpitations and lightheadedness, which he originally attributed to anxiety. There are short, but frequent periods of ventricular tachycardia, which are self-limiting.  This is called "NON-SUSTAINED VENTRICULAR TACHYCARDIA".  The underlying rhythm is sinus, with a remarkably long PR interval, and at least one episode of failure of the P wave to conduct, making "second-degree AV block, Type II" a possibility. It is difficult to thoroughly evaluate the underlying rhythm because it is not seen very often in this ECG. The rate of the underlying P waves is about 67 bpm.  The PR interval is .40 seconds (400 ms).  The "normal" QRS complexes are slightly widened, at about .10 sec (100 ms), which is typical of Type II AVB.  The ventricular QRS complexes are wide at .16 sec. (160 ms)

To assist you in using this tracing for teaching, we have also supplied a "marked up" version.  The P waves, both visible and hidden, are marked with red lines. The PR intervals are shown in the Lead V1 rhythm strip in green.  And the QRS complexes are numbered.  QRS complexes numbered 2, 3, 6, and 12 are sinus. The P wave AFTER QRS #5 is non-conducted.

To review the differentiation of ventricular tachycardia from supraventricular tachycardia with aberrant conduction, go HERE.

ECG Basics: Sinus Bradycardia With First-degree AV Block

Fri, 01/10/2014 - 15:52 -- Dawn

This is a nice teaching strip of a slowing sinus bradycardia that began around 40 bpm, and is slowing.  It is a good example of how the sinus node slows down - there is no abrupt change of rates, rather a change with each R-to-R interval.  There is also a first-degree AV block, reflecting slowing of conduction in the AV node.  The PR interval is slightly variable at .28 sec. to about .32 sec.  This is a good strip to begin talking about treatment of bradycardias with beginner students, as there is no second- or third-degee AVB, but the patient is very likely to be symptomatic now, or very soon.  Atropine would probably improve this rate in a symptomatic patient, but if there is time, a 12-Lead would be a good idea to rule out acute M.I.  Inadvertently raising the rate too much in the injured heart can lead to pump failure, while leaving the patient poorly-perfused in a bradycardia will starve the heart.  A transthoracic or temporary IV pacemaker might be a better choice for some patients because of our ability to choose the rate.



Subscribe to RSS - Long PR interval