A68-year-old retired postman presents to the clinic with dull intermittent left-sided chest pain over the last few weeks. the pain occurs after he mows his lawn or chops wood. he says that the pain radiates to the left side of his jaw but nowhere else. he has felt light-headed and nauseated with the pain but has had no other symptoms. he states when he sits down for several minutes the pain goes away. ibuprofen, tylenol, and antacids have not improved his symptoms. he reports no recent weight gain, weight loss, fever, or night sweats. he has a past medical history of high blood pressure and arthritis. he quit smoking 10 years ago after smoking one pack a day for 40 years. he denies any recent alcohol use and no drug use. he is married with two healthy children. his mother died of breast cancer, and his father died of a stroke. his younger brother has had bypass surgery. examination finds the client healthy appearing and breathing comfortably. his blood pressure is 140/90, and he has a pulse of 80. his head, eyes, ears, nose, and throat examinations are unremarkable. his lungs have normal breath sounds, and there are no abnormalities with percussion and palpation of the chest. his heart has a normal s1 and s2 and no s3 or s4. further workup is pending. which disorder of the chest best describes these symptoms