Reservoir Pressure Analysis in Group 2 Pulmonary Hypertension

Abstract

<h3>Purpose</h3> The reservoir-wave model, based on the 3-element Windkessel, proposes that the pressure waveform consists of a reservoir pressure (Pres) related to arterial expansion and recoil and a superimposed pressure wave (excess pressure, Pex) generated by forward (ventricular stroke volume and input impedance) and backward travelling waves (related to local arterial properties). In this study we aim to describe Pres in Group 2 isolated post-capillary (IPC) and combined pre and post-capillary (CPC) pulmonary hypertension (PH). <h3>Methods</h3> Pressure and velocity data were acquired simultaneously using a dual-tipped pressure and doppler flow sensor wire during right heart catheterisation. The data were processed offline using customised Matlab software. CPC PH was defined as pulmonary capillary wedge pressure (PCWP) >15mmHg, mean pulmonary arterial pressure (mPAP)>20mmHg and PVR≥3 WU. <h3>Results</h3> Pres but not Pex was higher in CPC compared to IPC PH (Table). A representative pressures and flow tracing is shown in the figure. Higher PA pressures in CPC PH is due to higher Pres secondary to higher PVR, PAC and PCWP. Pres correlated to pulmonary vascular resistance (PVR)(p=0.002;r=0.58),pulmonary capillary wedge pressure(PCWP)(p<0.001;r=0.84) and heart rate(HR)(p=0.01;r=0.487); and negatively correlated to pulmonary artery capacitance(PAC)(p<0.001; r=0.68), but not stroke volume(SV). <h3>Conclusion</h3> This is the first study to compare Pres in group 2 PH. Higher PA pressures in CPC PH is due to higher Pres and not Pex. This suggests input impedance and wave reflection may not be the dominant mechanism in CPC PH.