A 21 year old man was referred by primary care physicians with complaints of attacks of thick tongue lasting few minutes, of one year's duration. The attacks had increased in frequency over the previous month. He also complained of lethargy, abdominal pain, intermittent dysphagia, breathlessness on accustomed exertion, and mild headache of the same duration. On examination he was of average build and nourishment, and was breathless at rest. His pulse rate was 110 breaths/min, with a low pulse volume. Blood pressure was 80/70 mm Hg. He had raised jugular venous pressure, pedal oedema, tender hepatomegaly, and ascites. There was cardiomegaly and murmur of tricuspid regurgitation. On active movements of the tongue it became broad, thick, and stiff; and came back to normal after few minutes. The rest of the general and systemic examinations was normal. An earlier non-contrast enhanced cranial computed tomogram is shown in fig 1.

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(1)	What is the underlying condition, which can explain his thick tongue and cranial computed tomogram abnormalities?
(2)	What is the pathophysiology of his cardiac failure?
(3)	What are the other cardiovascular manifestations of this condition?