pheochromocytoma paroxysmparoxysmal hypertensionparoxysmal fibrillationparoxysmal nocturnal diseasedefine paroxysmalparoxysmal atrialparoxysmal medical definitionsymptomatic paroxysmal hypertensionmeaning of paroxysmalparoxysmal coughing treatmentparoxysmal nocturnal dyspnoeaparoxysmal hypertension example