Canon A wave is seen in:

Ans. (b) Complete heart blockRef.-.Harrison 18th edition, chapter 227:* The a wave reflects right atrial presystolic contraction and occurs just after the electrocardiographic P wave, preceding the first heart sound (Sj).* The a wave is not present with atrial fibrillation.* Canon a wave occurs with# Atrioventricular (AV) dissociation/ complete heart block due to right atrial contraction against a closed tricuspid valve.# Wide complex tachycardia like ventricular tachycardia* A prominent a wave is seen in patients with reduced right ventricular compliance like Right ventricular failure.