Measuring right ventricular function in the normal and hypertensive mouse hearts using admittance-derived...

Area of Science:

• Cardiovascular Physiology
• Pulmonary Hypertension Research
• Animal Models in Disease

Background:

• Mice are crucial models for cardiovascular disease research.
• Accurate assessment of right ventricular (RV) function is vital for pulmonary vascular diseases like pulmonary hypertension.
• Existing techniques for RV function assessment in mice are less established than for left ventricular function.

Purpose of the Study:

• To demonstrate the feasibility of measuring RV pressure-volume loops in mice.
• To investigate the impact of hypoxia-induced pulmonary hypertension (HPH) on RV function and ventricular-vascular coupling.
• To assess RV contractile reserve using dobutamine challenge in HPH mice.

Main Methods:

• Utilized an admittance catheter to obtain pressure-volume loops in anesthetized, open-chested mice.
• Compared mice with 10-day chronic hypoxia-induced pulmonary hypertension (HPH) to control (CTL) mice.
• Measured parameters before and during vena cava occlusion, and assessed cardiac reserve with dobutamine infusion.

Main Results:

• HPH mice exhibited increased RV mass and systolic pressure, decreased cardiac output, and impaired ventricular-vascular coupling (reduced E(es)/E(a)).
• Preload recruitable stroke work (PRSW) and dP/dt(max)-EDV relationship increased in HPH mice.
• Dobutamine challenge revealed a diminished RV contractile reserve in HPH mice compared to controls.

Conclusions:

• 10 days of HPH in mice leads to RV hypertrophy, ventricular-vascular decoupling, and reduced RV contractile reserve.
• RV pressure-volume measurements are feasible in mice and provide valuable insights into ventricular-vascular interactions.
• This technique aids in understanding RV dysfunction in pulmonary vascular diseases.