This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': "Giant 'a' waves in JVP occur in all except: \nSelect and explain. \nA. Junctional rhythm, B. Pulmonary hypeension, C. Tricuspid regurgitation, D. Complete hea block", 'role': 'user'}, {'content': "Answer: C \nExplanation: Answer is C (Tricuspid Regurgitation) Tricuspid stenosis (not Tricuspid regurgitation) is associated with large or 'a' giant waves. `a' waves in JVP: Are positive waves, due to distension produced by Right atrial contraction. Large 'a' waves indicate atrium is contracting against increased resistance. Large 'a' waves : Tricuspid stenosis Pulmonary stenosis Pulmonary hypeension Cannon 'a' waves : Regularly - During junctional rhythm Irregularly - Atrioventricular dissociation with ventricular tachycardia - Complete hea block Absent `a' waves : Atrial fibrillation", 'role': 'assistant'}]