title: Hyperdynamic Right Heart Function in Graves' Hyperthyroidism Measured by Echocardiography Normalises on Restoration of Euthyroidism.
abstract: BACKGROUND
  Graves' hyperthyroidism commonly causes tachycardia and may result in pulmonary hypertension and high output cardiac failure. There is limited information regarding the effect of treatment on cardiac function measured using modern echocardiographic techniques.
  
  
  METHODS
  Eight individuals with Graves' hyperthyroidism, aged 22-64 years, underwent comprehensive transthoracic echocardiography at three time points: before treatment, two weeks after commencement of carbimazole, and at six months or more when euthyroid. Exercise capacity was assessed using the 6-minute-walk-distance (6MWT), and quality of life was assessed by Medical Outcome Study 36-item Short-Form Health Status Survey.
  
  
  RESULTS
  All individuals were rendered euthyroid by final assessment. At presentation, there was evidence of hyperdynamic right ventricular function as measured by peak systolic velocity of the free wall of the tricuspid annulus, tricuspid annular plane systolic excursion and right ventricular ejection fraction, which normalised after resolution of thyrotoxicosis. Baseline heart rate correlated significantly with severity of the thyrotoxicosis for either free T4 (r = 0.91, p=0.01) or free T3 (r=0.94, p=0.001). No individual had measurable pulmonary hypertension. Cardiac output was significantly lower in the euthyroid compared to the thyrotoxic state (p=0.03). A higher baseline TSH-receptor antibody titre corresponded to a greater improvement in exercise capacity (r=0.76, p<0.05) and physical quality of life (r=0.73, p<0.05) on resolution of the hyperthyroidism.
  
  
  CONCLUSIONS
  Graves' hyperthyroidism causes increased cardiac output and a hyperdynamic right ventricle which normalise on restoration of the euthyroid state.
authors.affiliation: Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Qld, Australia; Queensland Diabetes and Endocrine Centre, Mater Misericordiae Hospital, Brisbane, Qld, Australia. Electronic address: stephanie_teasdale@hotmail.com.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Teasdale
authors.affiliation: Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Qld, Australia; School of Medicine, University of Queensland, Brisbane, Qld, Australia.
authors.forename: Warrick J
authors.initials: WJ
authors.lastname: Inder
authors.affiliation: Endocrine Hypertension Research Centre, University of Queensland School of Medicine, Princess Alexandra Hospital, Brisbane, Qld, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Stowasser
authors.affiliation: School of Medicine, University of Queensland, Brisbane, Qld, Australia; Nambour General Hospital, Nambour, Qld, Australia.
authors.forename: Tony
authors.initials: T
authors.lastname: Stanton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D004452:Echocardiography; D005080:Exercise Test; D005260:Female; D006111:Graves Disease / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume; D016278:Ventricular Function, Right
keywords: Graves; Pulmonary hypertension; Right heart function; Strain; TAPSE; Thyroid