The most likely mechanism of the tachycardia in the previous case is atrial flutter with an initial 2:1 atrioventricular (AV) conduction, followed by 1:1 AV conduction that produced the BCT (because of aberrant conduction).
The patient is a 28 year old male with no known history of heart disease. He is being treated with sodium valproate for epilepsy.
The body is a complex and marvellous thing. In the words of Nathanael West (1903-1940): "Under the skin of man is a wondrous jungle where veins like lush tropical growths hang along over-ripe organs and weed-like entrails writhe in squirming tangles of red and yellow".