title: Cardiac functional reserve is diminished in growth hormone-deficient adults.
abstract: Various studies have shown that patients with severe growth hormone deficiency (GHD) have diverse changes in left ventricular (LV) size or performance but so far there is no direct indication of cardiac reserve ability to maintain the circulation during peak exercise. We tested the hypothesis that patients with severe GHD have reduced cardiac reserve function compared with healthy controls. Eighteen patients with severe GHD were studied and compared with 18 age-, sex-, and body mass index (BMI)-matched healthy controls. Peak cardiac power and cardiorespiratory fitness were investigated using noninvasive hemodynamic measurements during maximal cardiopulmonary exercise testing. Compared with matched controls, the cardiac power of GHD patients during exercise to volitional exhaustion was significantly reduced by 15% (mean +/- SD: 4.4 +/- 1.0 watts (W) vs. 5.2 +/- 1.0 W, P= 0.02), despite attaining similar aerobic exercise peaks (VO(2max), GHD: 2390 +/- 822 mL/min vs. controls: 2461 +/- 872 mL/min, P= 0.80) and similar peak respiratory exchange ratios. The lower peak cardiac power could not be accounted for by peripheral alterations because both groups reached similar peak exercise systemic vascular resistances. Patients with GHD also had lower cardiac chronotropic reserve (peak heart rate: 154 +/- 21 bpm vs. 174 +/- 11 bpm, P= 0.001) and a lower cardiac pressure-generating capacity (systolic blood pressure [SBP] 160 +/- 25 mmHg vs. 200 +/- 15 mmHg, P < 0.0001). Using this robust noninvasive method of assessing functional cardiac pumping capacity we have for the first time shown that patients with severe GHD have a significantly impaired cardiac functional reserve associated with chronotropic incompetence and impaired pressure-generating capacity.
authors.affiliation: Department of Endocrinology, Leeds General Infirmary, Leeds, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Moisey
authors.forename: Steve
authors.initials: S
authors.lastname: Orme
authors.forename: Diane
authors.initials: D
authors.lastname: Barker
authors.forename: Nigel
authors.initials: N
authors.lastname: Lewis
authors.forename: Lisa
authors.initials: L
authors.lastname: Sharp
authors.forename: Richard E
authors.initials: RE
authors.lastname: Clements
authors.forename: David F
authors.initials: DF
authors.lastname: Goldspink
authors.forename: Lip-Bun
authors.initials: LB
authors.lastname: Tan
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001794:Blood Pressure; D049628:Body Size; D016022:Case-Control Studies; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006339:Heart Rate; D006439:Hemodynamics; D019382:Human Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use; D006801:Humans; D007018:Hypopituitarism / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D010101:Oxygen Consumption; D011994:Recombinant Proteins / Q000627:therapeutic use; D014655:Vascular Resistance
chemical_list: D011994:Recombinant Proteins; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I