Cardiology MCQ: AV block after cardiac surgery

Complete AV block requiring permanent pacemaker implantation is more likely after:
a) Coronary artery bypass grafting
b) Aortic valve replacement
c) Mitral valve replacement
d) None of the above
Correct answer: b) Aortic valve replacement
Complete heart block can occur after aortic valve replacement as the conduction system is closely associated with the location of the aortic valve. Pre-existing extension of calcification from aortic valve to the conduction system can cause complete heart block. This can be accentuated by the pressure of the artificial valve on the conduction system. Injury to the conduction system can also be due to sutures of the valve ring impinging on it. The pressure due to the valve on the calcareous material around the conduction system is responsible for complete heart block which occurs in sutureless aortic valve replacement. Injury to surrounding tissue causing edema and compression of the conduction system is a potential cause of reversible postoperative complete heart block.
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Source: Cardiophile MD - May 15, 2015 Category: Cardiology Authors: Prof. Dr. Johnson Francis, MD, DM, FACC, FRCP Edin, FRCP London Tags: Cardiology MCQ DM / DNB Cardiology Entrance Source Type: blogs