Complex sentence: Consequently, diethylene glycol dinitrate has occasionally been used medically to relieve angina, substernal chest pain associated with impaired cardiac circulation, since the concurrent headache it induces is somewhat less severe than other nitro compounds.
Split into simpler sentences: Consequently, diethylene glycol dinitrate has occasionally been used medically to relieve angina, substernal chest pain associated with impaired cardiac circulation. The rational is that the concurrent headache it induces is somewhat less severe than other nitro compounds.