Recent studies suggest right ventricular (RV) stiffness is important in pulmonary hypertension (PH) prognosis. Smaller stroke volume (SV) variation after a certain RV end-diastolic pressure (EDP) respiratory variation as assessed by spectral transfer function (STF) may identify RV stiffness. Our aim was to evaluate RV stiffness in monocrotaline (MCT)-induced PH progression and to validate STF gain between EDP and SV as marker of stiffness. Seven-week old male Wistar rats randomly injected with 60mg.Kg-1 MCT or vehicle were divided into 3 groups (n=12 each) according to cardiac index (CI): controls (Ctrl), preserved CI (MCT pCI), and reduced CI (MCT rCI). All underwent RV pressure-volume (PV) evaluation 24-34 days after MCT, under halogenate anesthesia and constant positive-pressure ventilation. End-diastolic stiffness (βi), end-systolic elastance (Eesi), arterial elastance for indexed volumes (Eai) and preload recruitable stroke work (PRSW) were obtained and beat-to-beat fluctuations during ventilation assessed by STF. Eai was the strongest determinant of CI, alongside βi, but not PRSW. MCT rCI showed impaired ventricular-vascular coupling (VVC) and higher βi, along with low EDP-SVi STF gain, denoting impaired preload reserve. On multivariate analysis βi and not Eesi correlated with EDP-SVi STF gain (P <0.001). ROC curve analysis of EDP-SVi STF gain showed an area under curve of 0.84 for βi prediction (P=0.002). Afterload, impaired VVC and RV stiffness are major players in RV failure. RV stiffness can be assessed by STF gain analysis of respiratory fluctuations between EDP and SVi which may constitute a prognostic tool in PH.
- Diastolic dysfunction
- right ventricular failure
- pulmonary hypertension
- spectral transfer function analysis
- Copyright © 2016, American Journal of Physiology-Heart and Circulatory Physiology