This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ECG and Arrhythmia 2, Subject name: Medicine
Which is the most common mechanism of arrhythmia? 
Select and explain. 
A. Re-entry, B. Early after depolarization, C. Late after depolarization, D. Automaticity
A: Re-entry
Answer: A: Re-entry 
Explanation: MC arrhythmia mechanism is re-entry. Re-entry Circulation of an activation wave around an inexcitable obstacle. It is d/t non-homogeneity in myocardial conduction and recovery propeies. The presence of a unidirectional block with slow conduction to allow for retrograde recovery of the blocked myocardium allows the formation of a circuit Two classic examples of re-entry- VF due to acute myocardial ischemia Polymorphic VT in patients with ion channelopathies such as the Brugada syndrome, LQTS, or catecholaminergic polymorphic VT.