Blurb: SVT is TACHY (150 - 250 bpm), REGULAR (must be regular; if not regular, it's not SVT, it might be Afib or MAT), NARROW QRS rhythm (<3ss, or <0.11sec). Tx: adenosine to slow the heart down. ~Qt
1. Rate:
SVT is a TACHY tachy rhythm.
2. Rhythm:
SVT is a REGULAR rhythm arrhythmia. Regular means the same morphology repeats throughout the entire strip. No differences in any section with another section throughout the strip.
Same beat morphology in every beat? In SVT, every beat morphology is the same, looking exactly like each other
3. Axis
Skip this for now.
4. Width:
Read from left to right.
SVT is different from V-tach in that the QRS complex of SVT is narrow (QRS less than <0.11 sec or less than 3ss or less than <1 large square horizontally). SVT's have NARROW QRS.
Same P in every beat? In SVT, P wave is unidentifable, meaning you can't tell if P is P or P is T wave. It looks like P is T, i.e., P is merged with T wave, therefore, PR interval = TR interval = .12sec- 0.20sec = 3-5ss
Same PR interval in every beat? Since P is merged with T wave, you can count PR interval as TR interval.
5. Height:
skip this for now.
II - Tx:
The rhythm above is too fast. All we can tell is that the ventricles are depolarising normally, as indicated by the narrow QRS complex.
This rhythm needs slowing down:
- Adenosine is the drug used for slowing down the heart.
- Vagal maneuver
- Synchronized cardioversion (if applicable)
- Catheter ablation (if rhythm keeps coming back and pt is symptomatic)
Once the rhythm is slowed down to below 140 bpm it is usually possible to identify it. It may then look like one of the categories discussed above and then further treatment can be decided upon.
Read more here:
https://www.dropbox.com/s/xao9lec9yuqa9nz/13.0-%20ACLS-2013-e-PUB-SVT%20Uncertain-%2810-13.11-2014%29-LOCK.pdf?dl=0#
http://www.practicalclinicalskills.com/supraventricular-tachycardia
http://www.nottingham.ac.uk/nursing/practice/resources/cardiology/svt/supra_ventricular.php
http://www.aafp.org/afp/2010/1015/p942.html
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