Complex sentence: While Schiavo's heat attack was due to a postassium deficiency, it unclear if Schiavo had bulimia and even less clear that the supposed bulimia or other wieght control problems contributed to her potassium deficiency and therefore her heart attack.
Split into simpler sentences: While Schiavo's heat attack was due to a postassium deficiency. It is less certain that eating disorder was bulimia or some other wieght control problem and if that problem contributed to her potassium deficiency and therefore her heart attack.