There's always a bit of hesitation and perplexity when it comes to interpret an ECG especially the arrhythmias. Let me share few basics of this aspect so that you get total clarity. PR interval always begin with the beginning of the P wave to the beginning of QRS. Now, this PR is normally of 120 to 200 milliseconds. Otherwise, it's 0.12 to 0.20 seconds. Otherwise, it's of three to five small squares.
Now, if the PR interval is more 200 milliseconds, its first degree heart block. If it happens to be less than 120 milliseconds, it signifies an accessory pathway between atria and ventricles causing preexcitation. If the PR interval is prolonged and further prolonged with each successive beat till a QRS is dropped, it's known as second degree heart block or also as Wenckebach phenomenon . Short PR interval is also noticed in AV junctional rhythm also known as nodal rhythm. There are two…
