A 95-year-old woman arrived at the Emergency Department complaining of palpitations.
Upon examination, her ECG revealed a heart rate of 144.
Below is the ECG report for reference.
What is your diagnosis?
Why do you think so?
Discussion:
The theme for the above case (Similar to the previous case) is "Narrow-Complex REGULAR Tachycardia"
The common differential diagnosis of narrow complex regular tachycardia is: 1) Sinus tachycardia. 2) SVT. 3) Atrial Flutter with a fixed block.
For Sinus Tachycardia, you should see a clear single P wave before each complex. Here is an example:
For SVT, you wouldn't usually be able to see any clear P waves anywhere. Here is an example:
For Atrial Flutter, you would see more than one P wave before each complex. Here is an example:
As I mentioned in the last case, I used to work with the above rules for a long time & things were going well till I met cases like the above one & which taught me a few tips that changed my way of looking at the ECGs completely.
For the second time, if you apply the above rules to the case above, you will get it wrong!
Let's analysis the ECG:
This case is even more interesting as no matter what you do with the ECG, there is only one positive wave before each complex.
The differential diagnosis here will depend on whether these waves (in between the complexes) are T waves & this is SVT, or they are P waves & this is Sinus Tachycardia with 1st degree heart block, unfortunately, you must decide as the treatment is completely different.
Let's analysis the ECG:
The initial clue in this case was the heart rate (144). This is a relatively slow heart rate for SVT, & a perfect heart rate for Atrial Flutter (around 150).
The second clue here is the "Bix Rule". When you see something that looks like a P wave exactly in the middle between 2 complexes, expect that there are 2 more P waves hidden in the complex before & the complex after. i.e. There is a good chance that this is a case of atrial flutter.
The Final Answer:
So, because of that, & because the heart rate was fixed around a specific number while observing her despite having IV fluid, my diagnosis was ATRIAL FLUTTER.
Because she was allergic to BB, I treated her with CCB (Verapamil) & shortly after I got this.
Now you can see the flutter waves in V1 with a variable block.
The Learning Points:
Both cases were Atrial Flutter, the learning points from the two cases are:
The common differential diagnosis of narrow complex regular tachycardia is Sinus tachycardia, SVT, or Atrial Flutter with fixed block.
Think atrial flutter if the rate is around 150.
Our eyes are not trained for some reason to see the inverted P waves, & they automatically see them as inverted T waves, so when you think that there might be some inverted P waves there, flip the ECG upside down.
Use the Bix Rule. When you see something that looks like a P wave exactly in the middle between two complexes, expect 2 more P waves hidden in the complex before & the complex after, & treat it as an atrial flutter until proven otherwise.
For Further Learning:
I hope you find this useful.
Best of luck.
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