This episode looks at the physiological electrical mechanisms that keep a heart beating - and what happens when the rhythm of life goes awry.

This episode looks at the physiological electrical mechanisms that keep a heart beating regularly and efficiently - and what happens when this most essential rhythm of life goes awry. The program takes viewers from New York to Brazil and into the lives of patients who suffer similar symptoms that actually signal different disorders. The range of treatment options - if not cures - is startling.