Assessment of pulmonary artery stiffness by multiparametric cardiac magnetic resonance-surrogate for right heart catheterization

Abstract

Background: Cardiac magnetic resonance (CMR) imaging allows for multiparametric assessment of healthy pulmonary artery (PA) hemodynamics. Gender- and aging-associated PA stiffness and pressure alterations have remained clinically unestablished, however may demonstrate epidemiological differences in disease development. The aim of this study is to evaluate the role of CMR as a surrogate for catheter examinations by providing a comprehensive CMR assessment of sex- and age-related reference values for PA stiffness, flow, and pressure.

Methods and results: PA hemodynamics were studied between gender and age groups (>/<50 years) using phase-contrast CMR. Corresponding correlation analyses were performed. 179 healthy volunteers with a median age of 32.6 years (range 11.3-68.2) were examined. Males demonstrated increased PA compliance (median [interquartile range] or mean ± standard deviation) (20.8 mm²/mmHg [16.6; 25.8] vs. 19.2 ± 7.1 mm²/mmHg; P < 0.033), higher pulse wave velocity (2.00 m/s [1.35; 2.87] vs. 1.73 m/s [1.19; 2.34]; P = 0.018) and a reduced full width half maximum (FWHM) (219 ± 22 ms vs. 235 ± 23 ms; P < 0.001) than females. Mean, systolic, diastolic PA pressure and pulmonary proportional pulse pressure were significantly elevated for males compared to females (P < 0.001). Older subjects (>50 years) exhibited reduced PA elasticity (41.7% [31.0; 52.9] vs. 66.4% [47.7; 83.0]; P < 0.001), reduced PA compliance (15.4 mm²/mmHg [12.3; 20.7] vs. 21.3 ± 6.8 mm²/mmHg; P < 0.001), higher pulse wave velocity (2.59 m/s [1.57; 3.59] vs. 1.76 m/s [1.24; 2.34]; P < 0.001) and a reduced FWHM (218 ± 29 ms vs. 231 ± 21 ms; P < 0.001) than younger subjects.

Conclusions: Velocity-time profiles are dependent on age and gender. PA stiffness indices deteriorate with age. CMR has potential to serve as a surrogate for right heart catheterization.

Keywords: cardiovascular magnetic resonance; hemodynamics; pulmonary artery pressure; pulmonary artery stiffness; pulse wave velocity; reference values; right heart catheterization.

Figure 1

Velocity-time and area-time curve in the pulmonary artery by flow-sensitive CMR. Typical velocity-time curve (solid line) and area-time curve (dotted line) in the main pulmonary artery of a 17.9 years-old female participant. Calculation of vessel characteristics such as upslope, downslope, vessel areas and full width half maximum. AT, time-to-maximum velocity; DT1, deceleration time maximum-to-zero crossing; DT2, deceleration time maximum-to-minimum; FWHM, full width half maximum, T area_max, time-to-maximum area.

Figure 2

Age-dependent velocity-time curves. Velocity-time curves in the main pulmonary artery from (A) a young participant (female, 18 years) and (B) an older participant (female, 63 years). Typically, upslopes are larger in older subjects, whereas downslopes are smaller. Angulations are presented as a surrogate for slopes values.

Figure 3

Correlations between the different parameters for assessing pulmonary artery stiffness. Scatter plots illustrating the linear correlations including 95% confidence intervals between different parameters of PA stiffness and age. *, Spearman's Rho correlation, ΔP_Peak, pulmonary artery pressure drop.

Figure 4

Assessment of PA stiffness measures by quantitative phase-contrast CMR. Male gender and older age are associated with increased pulmonary artery stiffness and altered velocity-time profiles. (A) Magnitude of phase-contrast CMR. (B) Phase of phase-contrast CMR. (C) Velocity-to-time profile curve. The white arrow indicates one of the important parameters (“full width half maximum”) for describing the stiffness properties. PA, pulmonary artery; PAP, pulmonary artery pressure, ΔP_Peak, pulmonary artery pressure drop.