EKG of the Week
/+ EKG Interpretation
Atrial flutter
The teaching point I want to start with is that the EKG reading by the computer (what was printed on the paper when the EKG came out of the machine) was SINUS TACHYCARDIA. That is obviously not correct so this is another example where you need to be careful not to believe the computer.
Let's think about rhythms that are narrow, regular and fast SINUS TACHYCARDIA is narrow, regular and fast - but is it likely to be this fast? The quick estimate for maximal predicted sinus rate is 220 minus age. So for this 60 year old around - around 160 would be the predicted maximum. But this is not a partient on a treadmill, it is a patient lying in a bed. While there are exceptions, usually sinus tach on a resting EKG is under 140 or so in adults.
SUPRAVENTRICULAR TACHYCARDIA is also narrow and fast. While there are exceptions (ectopic and junctional tachycardias are somtimes sometimes slower) the usual rate of SVT (AVNRT) is faster, >160 to around 225. So this one is a bit slow...
ATRIAL FLUTTER - the rate of the atrial activity is around 300 (250-350), so flutter with 2:1 conduction is frequently right at 150. So when I see a narrow, regular rhythm between 140-160 I think of atrial flutter and go looking for flutter waves - and when you're looking for flutter wavces, they are easy to march out.
Further Reading:
Life in the Fast Lane: Atrial Flutter, SVT, AVNRT
