It is uncommon to have pulmonary hypertension. We describe a case of pulmonary hypertension in which the underlying etiology was determined to be hyperthyroidism. Clinical manifestations of hyperthyroidism-induced pulmonary hypertension can result in cyanosis and heart rhythm abnormalities, which are indicators of right heart failure. The 56-year-old woman in this case study complained of tightness and edema in both of her legs when she arrived at the emergency room. Upon examination, cyanosis, atrial fibrillation, and right heart failure were noted. Due to the patient's prior history of hyperthyroidism, secondary pulmonary hypertension is currently complicating the condition. In order to improve the prognosis for pulmonary hypertension, the patient's thyroid function is managed with medication while receiving treatment in the hospital.