This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
Typical.JVP finding; in cardiac tamponade - 
Select and explain. 
A. absent 'Y' descent, B. Prominant 'a' wave, C. Absent 'a' wave, D. Prominent 'Y* wave
A: absent 'Y' descent
Answer: A: absent 'Y' descent 
Explanation: The accumulation of fluid in the pericardial space in a quantity sufficient to cause serious obstruction to the inflow of blood to the ventricles results in cardiac tamponade. This complication may be fatal if it is not recognized and treated promptly. The three most common causes of tamponade are neoplastic disease, idiopathic pericarditis, and renal failure. The three principal features of tamponade ( Beck's triad ) are hypotension, soft or absent hea sounds, and jugular venous distention with a prominent x descent but an absent y descent. ref : ( Harrison&;s principle of internal medicine,20 edition,pg no. 1572)