Problem: A 52-year-old man presents to the emergency room after a syncopal episode. The patient is awake, alert, and oriented; however, he becomes lightheaded whenever he tries to sit up. The medical history is significant for coronary artery disease and stable angina, which have been controlled with simvastatin and isosorbide dinitrate. The blood pressure is 70/45 mm Hg and the heart rate is 110/min; all other vital signs are stable. IV fluids are started as he is taken for CT imaging of the head. En route to the imaging suite, the patient mentions that he took a new medication for erectile dysfunction just before he began to feel ill. What is the metabolic cause of this patient's symptoms? Need Assignment Help? Increased endogenous nitric oxide synthesis Increased oxygen consumption Nitric oxide synthase inhibition Increased cGMP in vascular smooth muscle Increased PDE-5 concentration