A novel open chest method of right ventricular hemodynamics measurement in pulmonary hypertensive mice

Abstract

Objective: Right heart catheterization is the gold-standard for measurement of right ventricular hemodynamics. However, it is difficult to perform in mice. We thus aimed to establish a new open chest method to record and analyze the right ventricular hemodynamic parameters in intubated mice connected to a respirator under anesthesia. Methods: Eight-week old male C57BL/6 mice were divided into the control group, and the hypoxia group using completely random method. Mice in the hypoxia group were exposed in low pressure oxygen chamber, which simulated the environment of plateau (5 500 m altitude, 10% oxygen) for 3 weeks. Mice in the control group were exposed in normal pressure and oxygen environment. The mice were intratracheally intubated and connected to a respirator, chest was opened, right ventricular hemodynamics were measured with a needle (0.7 mm×19 mm) punctured into right ventricle (5 mm in death), which was connected to the measuring equipment. Results: The open chest procedure could be finished within 5-10 minutes. The successful rate was 100%. There was no significant difference in heart rate between control group and hypoxia group under anesthetia ((306.4±11.5) bpm vs.(320.4±16.0) bpm, P>0.05). Compared with the control group, both the right ventricular systolic pressure (RVSP) and the mean right ventricular pressure(mRVP)were increased in hypoxia group ((17.1±1.0)mmHg(1 mmHg=0.133 kPa) vs. (22.6±1.0) mmHg, P<0.01; (9.6±0.8) mmHg vs.(12.4±0.3) mmHg, P<0.01). Moreover, the absolute value of the maximal rate of increase in right ventricular pressure (dp/dtmax) and the maximal rate of decrease in right ventricular pressure (dp/dtmin) were higher in the hypoxia group ((421.3±30.6)mmHg/s vs.(639.7±47.7)mmHg/s, P<0.01; (-324.3±24.0)mmHg/s vs. (-496.5±40.6) mmHg/s, P<0.01), indicating the pathological status after hypoxia treatment. Conclusions: Right ventricular hemodynamics measurement with this open chest technique is easy to handle and can accurately reflect the right ventricular pressure in mice under physiological and pathological conditions.