肺高血圧症(肺静脈性)における肺動脈血管特性の解析―圧脈波反射波と局所脈波速度による検討

Analysis of Pulmonary Arterial Pressure Wave Reflection and Regional Pulse Wave Velocity in Patients with Pulmonary Venous Hypertension(PH)

要旨　肺静脈性肺高血圧(PH)の肺動脈血管特性を，圧脈波反射波(Pb)と局所脈波速度の分析によりcontrol群との対比から検討した．PH5例(僧帽弁狭窄)とcontrol10例を対象に，multisensor catheterによる主肺動脈同一部位の圧(Pm)と流速(Vm)の同時計測からWesterhofの式よりPbを求め，以下の各parameterを求めた．①peak Pb(t)，②R-peakVm(t)/R-R(心電図のR-R時間)，③R-peakPb(t)/R-R，④Reflection index(R.I.)：1心周期におけるPb(t)のPm(t)に占める面積比，⑤主肺動脈局所脈波速度(PA-PWV1)：収縮初期PmとVmの一次回帰式(water-hammer式)より算出．PeakPb，R.I.とPA-PWV1値はPH群がcontrol群よりも有意に高値を，R-peakVm/R-RとR-peakPb/R-R値はcontrol群がPH群よりも有意に高値を示した．PH例の主肺動脈では有意なPbの早期発現とPbの増高およびPA-PWV1の増大が観察された．これらはいずれも右室後負荷に作用し，PH例に特有な駆出血流加速期の短縮と駆出血流の2峰性変化に働くことを確認した．さらに，PH病変の本質を成す肺動脈の性状(硬さ)を評価するうえで，肺動脈局所脈波速度(PA-PWV1)はそのsurrogateとなる可能性が示唆された．

　Objectives: The present investigation compared and contrasted the pressure wave reflection and regional pulse wave velocity of the main pulmonary artery in patients with pulmonary hypertension(PH) and normal control subjects.

　Methods: Main pulmonary arterial flow velocity(Vm) and pressure(Pm) were simultaneously recorded using a multisensor catheter in 5 PH patients with mitral stenosis and 10 control subjects. Instantaneous pressure wave reflection(Pb) was calculated from Westerhof's equation every 2ms. To estimate the magnitude and timing of Pb, peakPb, R-peakPb/R-R(time interval between R of ECG and peakPb, R-R; R-Rinterval of ECG), R-peakVm/R-R(time interval between R of ECG and peak Vm) and reflection index(R.I.; area ratio of reflected and measured pressure waveform) were calculated. Regional pulse wave velocity of the main pulmonary artery(PA-PWV1) was also calculated by water-hammer formula(one point measurement).

　Results: PeakPb, R.I.and PA-PWV1(28±19mmHg, 0.45±0.03, 3.4±0.2m/s.) were significantly higher in patients with PH than in control subjects(8±2.0mmHg, 0.30±0.08, 1.9±0.3m/s.). R-peakPb/R-R and R-peakVm/R-R were significantly shorter in patients with PH(0.31±0.07, 0.17±0.03) than in control subjects((0.49±0.11, 0.28±0.06)

　Conclusions: It is concluded that PA-PWV1 and the magnitude of pressure wave reflection was significantly increased and peak Pb arrived earlier during ejection in patients with PH than in control subjects,resulting in the significant reduction of the acceralating phase of the ejection flow and the development of midsystolic notch in pulmonary flow velocity waveform which are both characteristic of PH. The differences in PA-PWV1 in PH and the control group seem proportionate to the difference in pulmonary arterial pressure. This may help justify studies that try to calculate PA-PWV1 noninvasively by simultaneous measurements of pressure and velocity as a surrogate for biophysical properties of the pulmonary artery in patients with PH.