title: Inappropriate sinus tachycardia.
abstract: Inappropriate sinus tachycardia (IST) is a syndrome in which the sinus heart rate is inexplicably faster than expected and associated symptoms are present. The heart rate at rest, even in a supine position, can exceed 100 beats/min; minimal activity accelerates the rate rapidly and substantially. Patients with IST may require restriction from physical activity. Mechanisms responsible for IST are understood incompletely. It is important to distinguish IST from so-called appropriate sinus tachycardia and from postural orthostatic tachycardia syndrome, with which overlap may occur. Because the long-term outcome seems to be benign, treatment may be unnecessary or may be as simple as physical training. However, for patients with intolerable symptoms, therapeutic measures are warranted. Even at high doses, β-adrenergic blockers, the first-line therapy, often are ineffective; the same is true for most other medical therapies. In rare instances, catheter- or surgically- based right atrial or sinus node modification may be helpful, but even this is fraught with limited efficacy and potential complications. Overtreatment, in an attempt to reduce symptoms, can be difficult to avoid, but is discouraged.
authors.affiliation: Department of Internal Medicine, Division of Cardiovascular Medicine, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, USA. brian-olshansky@uiowa.edu
authors.forename: Brian
authors.initials: B
authors.lastname: Olshansky
authors.forename: Renee M
authors.initials: RM
authors.lastname: Sullivan
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D001683:Biological Clocks / Q000502:physiology; D017115:Catheter Ablation / Q000379:methods*; D003864:Depression, Chemical; D019468:Disease Management; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D018377:Neurotransmitter Agents / Q000378:metabolism; D012849:Sinoatrial Node / Q000294:innervation / Q000378:metabolism / Q000503:physiopathology; D013616:Tachycardia, Sinus / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy; D014630:Vagus Nerve / Q000378:metabolism / Q000503:physiopathology
chemical_list: D000319:Adrenergic beta-Antagonists; D018377:Neurotransmitter Agents