Dr. Mattu walks us through a three step method to make identifying heart blocks easy. Just ask three qestions
1) What is the atrium doing? (regular, irregular rate?)
2) What is the ventricle doing? (morphology and thus location? rate?)
3) How are the two related? (Look at PR interval, is it regular? long then dropped QRS, longer, longer then drop? or randomly related? 1st, 2nd, 3rd degree blocks).

Commonly seen after ventricular reperfusion, and generally self limiting, this rhythm is important to recognize as managment with antiarrhythmics is not indicated (and may make the situation worse).  It is a result of a ventricular rhythm that is faster than the atrial rhythm and will generally resolve once the atrial rhythm exceeds the ventricular pacemaker.  Focus on recognizing the underlying causes, treating the cause and not the rhythm, or being watchfully patient as the case may require.  Follow the link to LITFL to learn more.

ECG Features

• Regular rhythm.
• Rate 50-110 bpm. (<50 is likely ventricular escape, > 110 is VT)
• Three or more ventricular complexes.
• QRS complexes >120ms.
• Fusion and capture beats.

Next time you see a narro complex tachycardia, take an extra look to see if your missing a flutter.
DDx Narrow Complex Tachycardia:
- Sinus tachycardia
- SVT (AVNRT)
- A Flutter with 2:1 conduction (hint: if rate 150 +/- 20 bpm then a flutter till proven otherwise)

The way to differentiate is to look at what the Atrium is doing. Look for P waves in all the leads. Granted V1 is still your go to, but look closer in all the leads. If you're not sure flip the ECG upside down to help your mind recognize inverted p waves for what they are.

Dr. Amal Mattu discuss ED differential for Rightward axis.  
BLUF: think about

• PE
  
• Na channel blocker toxicity 
• Lead misplacement

Check out the link for full details and quiz.