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Influence of frusemide on dynamic cardiac variables during exercise
Article first published online: 10 JUN 2010
© 1999 EVJ Ltd
Equine Veterinary Journal
Volume 31, Issue S30, pages 170–173, July 1999
How to Cite
LANGSETMO, I., WEIGLE, G. E., ERICKSON, H. H. and FEDDE, M. R. (1999), Influence of frusemide on dynamic cardiac variables during exercise. Equine Veterinary Journal, 31: 170–173. doi: 10.1111/j.2042-3306.1999.tb05211.x
- Issue published online: 10 JUN 2010
- Article first published online: 10 JUN 2010
- exercise-induced pulmonary haemorrhage;
Exercising horses have extremely high right and left atrial pressures. Limitation in ventricular function (i.e. relaxation) may play a role in these high pressures. We studied relaxation characteristics of the right ventricular myocardium and the impact of frusemide (2.0 mg/kg bwt i.v.) on these characteristics in horses exercising at 8, 10, 12 and 14 m/s. Exercise tests were performed 4 h after administration of frusemide. Right ventricular (RV) pressure was analysed using Fast Fourier Transform techniques to remove non cardiac components of the pressure signal. Mean right atrial (RA) pressure increased with exercise and was significantly attenuated at all speeds by frusemide. RV maximum and minimum rates of pressure change with respect to time (RV+dP/dtmax, RV-dP/dtmax) increased with exercise and RV relaxation time constant (RVτ) and time of RV relaxation from 65–20% of the difference between maximum and minimum ventricular pressure (Δ65–20) decreased with exercise. Frusemide produced no significant differences in +dP/dtmax, -dP/dtmax, RVτ or Δ65–20 except at 12 m/s where RVτ was longer after frusemide (23.4 ms for frusemide vs. 19.7 ms for control). Significant reductions in stroke volume were seen at 8, 10 and 14 m/s after frusemide. These results suggest that the reduction of atrial pressure by frusemide is not due to changes in ventricular relaxation rate.