Assessment of Ventriculo-Arterial Interactions in Early and Undifferentiated Pulmonary Hypertension Using Wave Intensity Analysis.

Background: Pulmonary wave intensity analysis uses pressure and velocity data to assess the intensity, direction, type, and timing of waves. Its application in early and undifferentiated pulmonary hypertension (PH) to characterize right ventricular (RV)-pulmonary arterial (PA) interactions has not been previously reported.

Methods: We hypothesized that wave intensity and speed would increase with mean PA pressure, while reflected wave timing would remain unchanged. Sixty patients with suspected PH underwent same-day right heart catheterization and cardiac magnetic resonance. PA pressure and pulmonary vascular resistance were measured via right heart catheterization; PA flow, RV volumes, and function were assessed by cardiac magnetic resonance. Wave intensity analysis was derived from pressure and velocity changes. Linear and logistic regression were used for analysis.

Results: Of the 60 patients (6 with mean PA pressure <20 mm Hg, 11 undifferentiated, 43 confirmed PH), all exhibited forward compression and decompression waves. A backward compression wave was present in 95%, while a backward decompression wave was found in 32%. Intensities of all 4 dominant waves increased with mean PA pressure (<0.01). Significant differences in reflection coefficient (=0.04) and wave speed (=0.01) were observed across PH subgroups. When present, the backward decompression wave showed the strongest associations with RV end-diastolic (β=-490.8) and end-systolic volumes (β=-495.9; both <0.01). Wave speed demonstrated the best performance for identifying abnormal RV end-diastolic volume and RV end-systolic volume (area under the curve, 0.73 and 0.80, respectively).

Conclusions: In early and undifferentiated PH, peak wave intensity and speed increases with mean PA pressure, while reflected wave timing is unchanged. Wave intensity analysis metrics may aid in detecting PA stiffening before overt hemodynamic or structural RV changes.