Atrial Fibrillation ECG

Question 1

ECG features of A fib are ?

Answer 1

A) Irregularly irregular rhythm
B) No P wave
C) absence of an isoelctric baseline
D) variable ventricular rate
E) QRS Complex< 120 Ms unless preexisting BBB, accessory pathway, rate related aberrant conduction
F) Fibrilatory waves may be fine <0.05 mm amplitude or Coarse>0.05 mm amplitude.

Question 2

Mechanism of atrial fibrillation?

Answer 2

The exact mechanism is not known. However, it requires an initiating event and a substrate for maintenance. The initiating event is often a focal activation or multiple wavelet mechanisms and the substrate for maintenance is always left atrial enlargement.

Question 3

What is focal activation in A fib ?

Answer 3

It is the initiation of focal atrial fibrillation waves through increased automaticity or micro reentry from the ectopic focus often located in the pulmonary veins.

Question 4

What is multiple wavelet mechanism in A fib?

Answer 4

These are small wandering wavelets that trigger Atrial fibrillation through reentry mechanism and maintain it through the large surface area of dialated left atrium

Question 5

What is the most common ventricular rate in A fib ?

Answer 5

110-160 BPM

Question 6

What is Ashman phenomenon in A fib ?

Answer 6

Ashman phenomenon occurs when a long RR interval is followed by short RR interval followed by aberrant QRS Complex

Question 7

What causes slow A fib? ( <60 BPM )

Answer 7

It occurs in hypothermia, digoxin toxicity