This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2019, Subject name: Medicine
Pericardial knock is seen in? 
Select and explain. 
A. Cardiac tamponade, B. Restrictive cardiomyopathy, C. Constrictive pericarditis, D. Acute pericarditis
C: Constrictive pericarditis
Answer: C: Constrictive pericarditis 
Explanation: Pericardial knock- early diastolic sound ( earlier than S3 ) indicates decreased ventricular compliance due to an external force heard in patients with constrictive pericarditis S3 is an early diastolic sound due to rapid ventricular filling with a large volume of blood so occur in patients with hyperdynamic circulation example : pregnancy, anemia, A-V shunts and congestive hea failure S4 filling of ventricle against a stiff ventricle so the atria have to give a final kick at end of diastole to completely empty itself