Terminology and handy hints on reporting holter monitors

Things to know:
1. Orthodromic means you can't see the P wave, but it implies that there is an AVRT.

2. The compensatory pause that you see after a ventricular ectopic is due to retrograde P waves.

3. When you are seeing night-time bradycardias down to 30bpm, you're expecting to see a few junctional escape beats.

4. A common cause of SVT is AJT (accelerated junctional tachycardia) - the junction entrains the AV node here.

5. In whom will you be expecting to see atrial tachycardia? It doesn't occur in stretched atria, rather in emphsematous atria or those that have had surgery because the scar creates reentrance.

6. When a patient with AF is exercising you will sometimes see a few P waves amongst the AF - this is because the patient's sinus node is competing with the AF chaos when the patient is exercising (because autonomic tone increases the sinus node output).

7. Commonest reason for AF is a sick sinus syndrome, whether it be caused by a scarred sinus, a stretched sinus or a degenerated sinus. What happens is that there is sinus node failure and so the AF is an escape rhythm.

8. Is it AF or an SVT? AF will regularize at heart rates >160bpm. Until then there will be a significant difference in the R-R intervals, so you can deduce that there is no AF if the R-R intervals are relatively close together and there is a relatively slow tachycardia.

9. The only time to really worry about the QT interval is when you look at the slow heart rates and note what it is, and then look at the fast heart rates and note that it is longer...because the QT interval is meant to SHORTEN with tachycardia...and it's when it doesn't that you get VF, because you set up an R on T phenomenon.

10. How do you decipher the cause of a pause?
Well, it's pretty easy because there's 3 steps:
1. Is there a PAC? Yes= blocked PAC. ...or a PVC? Yes= concealed retrograde conduction that has reset the AV node.
2. Is there at least a P? Yes= AV block
3. If there's no P, then the possibilities are a vagus sinus (sinus arrhythmia) or a sick sinus. If you think that it's a sick sinus, then you have to decide which disease it has?
The diseases that sinuses get are:
1. Sinus arrest...diagnosed because it ends in a junctional escape beat AND the length of the pause will NOT be a multiple of the R-R* interval of previous beats
2. Sinoatrial exit block, which can be Type I or Type II...diagnosed because it ends in a sinus beat AND Type II differentiated by the length of the pause being a multiple of the R-R interval of previous beats (because the sinus node discharge was BLOCKED but NOT interrupted)**.

*because the R-R interval is the same as the P-P interval.

** in Type I 2nd degree SAEB, the P-P interval progressively shortens.

SO...if you get down to the third step of there being no P and you don't think it's vagus, all you have to do is MEASURE THE R-R INTERVAL and MEASURE THE PAUSE (WHICH WILL ALSO BE AN R-R INTERVAL). If they don't match as multiples then you have either SA or SAEB1.
How to tell the difference between SA and SAEB1?
3 steps:
1. If the R-R pause is GREATER than the preceding 2 preceding R-R intervals added together, then it is SA because SAEB1 will always be LESS. Done!
2. If it's less, then you need to look at the 3 preceding R-R intervals, not just the 2 preceding ones. IS the first longer then the second and the second longer than the third? YES= SAEB1.
OR you could use the 2 you already measured and measure the first R-R after the pause. Same rule applies - that R-R after the pause will be longer than the one before the pause.
1. Look at the previous 3 P-P intervals. If they get shorter