Right ventricular pressure dynamics and stress echocardiography in pharmacological and exercise stress testing.

This research explores the impact of pharmacological stress testing (PST) and exercise stress testing (EST) on the dynamics of right ventricular pressure in horses. It concludes that PST, although less pronounced, shows similar effects on cardiac parameters and echocardiography as EST. The study adds that PST should be further assessed in normal horses and those with cardiac diseases, making it a potential addition to EST in better identifying exercise-induced cardiac dysfunction.

Methodology

• The study was carried out on five horses following a randomized crossover design where each horse underwent both PST and EST.
• High-fidelity pressure transducers were inserted in the right ventricle of the horses to monitor pressure changes continuously.
• Parameters including maximum and minimum pressure change rates (dP/dtmax and dP/dtmin) and pressure decay time constant (tau) were calculated.
• Electrocardiograms were taken continuously for 20 hours, and echocardiography was conducted before, during, and after the stress tests.
• The researchers also measured the plasma concentrations of cardiac troponin I, a protein released when the heart muscle is damaged, before and 3-4 hours after the stress tests.

Results

• Both the PST and EST led to a significant increase in dP/dtmax and dP/dtmin over the baseline, and a significant decrease in tau.
• Compared to PST, EST highlighted a noticeably enhanced dP/dtmax and dP/dtmin and a significantly reduced tau.
• The parameters measured two minutes post EST and five minutes post PST were not significantly different but were considerably less than the readings taken at the end of EST and during PST.
• The measurements of fractional shortening (FS) weren’t considerably different between PST and post EST, but both the measurements taken during PST and post EST were notably higher than baseline.
• Post PST, the concentrations of cardiac troponin I were significantly elevated and were higher than post EST.

Conclusion

• Comparing the outcomes, PST has a similar, though less marked, effect on the right-ventricular pressure dynamics and echocardiography as EST.
• Despite showing the release of higher cardiac troponin I levels than EST, the clinical implications of this finding are currently undefined.
• The results suggest that PST can serve as a crucial diagnostic tool to identify cardiac dysfunction in horses, complementing EST. However, further exploration is required for PST usage in both normal and cardiac disease-affected horses.