1. Place the catheter in warm PBS for at least 30 min to achieve stable recordings.

2. Set up the Millar catheter system including the catheter transducer and the data acquisition system.

3. Initiate anesthesia by weighing the mouse gently and placing in a chamber containing isoflurane at a concentration of 2.5%. Maintain anesthesia by restraining the sedated mouse on a heating pad, taping the upper and lower limbs at a isoflurane concentration of between 1 and 1.5%.

4. Restrain the sedated mouse on a styrofoam board with autoclave tape and place the mouse under a dissecting microscope (8× magnification).

5. Make an incision of skin at the right side of the neck, remove surrounding connective and fat tissues, and carefully dissect and expose the right external jugular vein.

6. Place two sutures below the vein, one lose suture near to the chest and one tight suture away from chest.

7. Cut a tiny hole (one third of the diameter of the vein) into the exposed right external jugular vein using fine micro scissors under microscope and gently insert the catheter into the hole of the isolated vein and tie the knot just tight enough.

8. Advance the catheter into the right ventricle by constantly monitoring the pressure waveform change from the venous pressure, to the right atrial pressure and eventually to the right ventricular pressure (RVP).

9. Record RVP and RV-dP/dt for 3 min when the records become stable, and save the records for analysis.

10. Analyze RVSP (right ventricular systolic pressure) and RV-dP/dt data using LabChart Pro 7.0 software and perform statistical analysis using SigmaPlot software.

11. Calculate mean PAP according to the equation: mPAP = 0.61 × RVSP + 2 (mmHg).