Right ventricular function during pharmacological and exercise stress testing in horses

• Published in: The veterinary journal (1997) 2017-09, Vol.227, p.8-14
• Main Authors: Decloedt, A., De Clercq, D., Ven, S., Vera, L., van Loon, G.
• Format: Article
• Language: English
• Subjects: Animals; Athlete’s heart; Blood Pressure; Cardiac remodelling; Echocardiography, Stress - drug effects; Echocardiography, Stress - veterinary; Exercise Test - veterinary; Female; Heart Rate; Horses - blood; Horses - physiology; Organ Size; Physical Conditioning, Animal; Pulmonary Artery - anatomy & histology; Pulmonary hypertension; Training; Treadmill; Troponin - blood; Ventricular Function, Left; Ventricular Function, Right
• ISSN: 1090-0233; 1532-2971
• DOI: 10.1016/j.tvjl.2017.08.001

•Right ventricular function was examined in healthy horses using exercise and pharmacological stress echocardiography.•Post-exercise and pharmacological stress echocardiography resulted in similar heart rates and cardiac output.•Cardiac troponin I concentrations were significantly elevated after pharmacological stress testing.•Pulmonary artery pressures were significantly higher post-exercise, with alterations of right ventricular function. The disproportionate rise of pulmonary artery pressure compared to systemic blood pressure during exercise can lead to detrimental right ventricular remodelling in endurance athletes. Horses may act as an extreme model of these athletic cardiovascular adaptations, as they show a three fold increase in pulmonary pressures during exercise. Right ventricular function was examined in ten healthy horses using post-exercise and pharmacological stress echocardiography in a randomised cross-over design. Exercise testing was performed on a treadmill while pharmacological testing was performed using an atropine-dobutamine infusion. Heart rate, systemic blood pressure and cardiac output during echocardiography were similar post-exercise compared to maximal pharmacological stress. Systolic pulmonary artery pressure was significantly higher during the exercise test (121±15mmHg) and during immediate post-exercise echocardiography (93±10mmHg) compared to maximal pharmacological stress (69±12mmHg). Right ventricular diameters as well as the ratio of systolic right to left ventricular area were higher post-exercise. Right ventricular fractional area change was significantly decreased post-exercise (40.5±6.2%) compared to a significant increase during pharmacological stress echocardiography (72.6±7.3%). Serum cardiac troponin I concentration was significantly higher 2h after the pharmacological test compared to baseline values and post-exercise, although the highest value was found post-exercise in the horse with the highest systolic pulmonary artery pressure and lowest right ventricular fractional area change. Pharmacological stress testing is not recommended in further studies on right ventricular adaptations in athletic horses, as this does not reproduce the effects of exercise.