title: Maximal exercise capacity and oxygen consumption of lambs with an aortopulmonary left-to-right shunt.
abstract: We determined maximal exercise capacity and measured hemodynamics in 10 6-wk-old lambs with an aortopulmonary left-to-right shunt [S, 57 +/- 11%, (SD)] and in 9 control lambs (C) during a graded treadmill test 8 days after surgery. Maximal exercise capacity (3.7 +/- 0.2 km/h and 10 +/- 5% inclination vs. 4.0 +/- 0.9 km/h and 15 +/- 0% inclination, P less than 0.02) and peak oxygen consumption (25 +/- 7 vs. 34 +/- 8 ml O2.min-1.kg-1, P less than 0.02) were both lower in the shunt than in the control lambs. This was due to a lower maximal systemic blood flow in the shunt lambs (271 +/- 38 vs. 359 +/- 71 ml.min-1.kg-1, P less than 0.01). Despite their high maximal left ventricular output, which was higher than in the control lambs (448 +/- 87 vs. 359 +/- 71 ml.min-1.kg-1, P less than 0.05), the left-to-right shunt could not be compensated for during maximal exercise because of a decreased reserve in heart rate (S: 183 +/- 22 to 277 +/- 38 beats/min; C: 136 +/- 25 to 287 +/- 29 beats/min) and in left ventricular stroke volume (S: 1.8 +/- 0.3 to 1.6 +/- 0.4 ml/kg; C: 1.0 +/- 0.3 to 1.3 +/- 0.2 ml/kg). We conclude that exercise capacity of shunt lambs is lower than that of control lambs, despite a good left ventricular performance, because a part of the reserves for increasing the left ventricular output is already utilized at rest.
authors: Department of Pediatrics, University of Groningen, The Netherlands.
authors: J W
authors: JW
authors: Gratama
authors: J J
authors: JJ
authors: Meuzelaar
authors: M
authors: M
authors: Dalinghaus
authors: J H
authors: JH
authors: Koers
authors: A J
authors: AJ
authors: Werre
authors: W G
authors: WG
authors: Zijlstra
authors: J R
authors: JR
authors: Kuipers
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D001011:Aorta / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D010805:Physical Conditioning, Animal; D011651:Pulmonary Artery / Q000502:physiology*; D012756:Sheep
chemical_list: D006454:Hemoglobins