A 26 year old man complains ofabdominal distension, swelling of the legs and easy fatigability. His blood pressure is 90/70mm Hg and pulse becomes difficult to feel on deep inspiration.JVP is grossiy elevanted and rises fuher on deep inspiration. He has pedal edema, ascites and tender hepatomegaly. Precordium is quiter with loud and some what early apical third hea sound. The probable diagnosis is -