Phosphodiesterase inhibitors for erectile dysfunction: sildenafil (Viagra, Revatio), tadalafil (Cialis), or vardenafil (Levitra) within the past 24 to 48 hours and after; can cause hypotension

a) Contraindications for nitrate therapy
b) Indications for thrombolytic therapy
c) Risk factors for atherosclerosis
d) Side effects of phosphodiesterase inhibitors