2016 Volume 56 Issue 4 Pages 45-53
Objectives: Although pulmonary hypertension (PH) caused by left heart disease (PH-LHD) is more common in PH, little is known about its properties of pulmonary artery (PA) in PH-LHD. The purpose of this study was to measure pulmonary regional pulse wave velocity (PWV) and to quantify the magnitude of reflected waves in patients with PH-LHD by the analysis of the pressure-velocity loops (PV-loop). Methods: High-fidelity PA pressure (Pm) and PA velocity (Vm) were measured in 11 subjects with PH-LHD (mean Pm>25 mmHg), 1 subject with atrial septal defect (ASD) without PH and 12 control subjects, using multisensor catheters. PWV was calculated as the slope of the initial part of the PV-loop in early systole. The similarity in the shapes of the pressure and flow velocity waveforms over one PV-loop was quantified as the magnitude of reflected wave by calculating the standard error of the estimate (Sy/x) from linear regression analysis between Pm and corresponding Vm. PWV and Sy/x during a Valsalva maneuver (VM) were also assessed in nine control subjects. Results: The contour of PV-loop was so characteristic between control and PH-LHD. Max. PWV (349 cm/s) was recorded in PH-LHD and min. PWV (111 cm/s) was recorded in ASD. VM increased Pm (12[7–15] mmHg vs 50[18–110] mmHg; p=0.009) and PWV (200[148–238] cm/s vs 260[192–306] cm/s; p=0.009) significantly without significant increase of Sy/x (19.6[12.7–28.9]% vs 28.2[19.3–40.7]%; p=0.079). Although Sy/x was significantly higher in PH-LHD than in control and ASD (17.5[8.4–28.9]% vs 31.0[14.3–36.3]%; p=0.009, ASD: 18.2%), no significant difference was found in PWV between PH-LHD and control (269[159–349] cm/s vs 203[154–289] cm/s; p=0.089). Conclusions: 1) The magnitude of wave reflection was elevated in PH-LHD significantly as compared with control and ASD. 2) Despite the significant increase in PA-PWV caused by abrupt elevation in Pm during Valsalva maneuver in control, chronic elevation in Pm did not increase PA-PWV in PH-LHD significantly. It was hypothesized that the pulmonary artery constituted a self-regulating system for maintaining the arterial stiffness stable against the chronic elevation in Pm in PH-LHD by a remodeling of increasing proximal pulmonary arterial cross-sectional area gradually, which was compatible with the Moens–Korteweg equation. The PV-loop could provide a new simple and conventional method for assessing the pulmonary arterial properties, clinically.
