title: RV dysfunction in pulmonary hypertension is independently related to pulmonary artery stiffness.
abstract: OBJECTIVE
  This study investigated whether right ventricular (RV) adaptation to chronic pressure overload is associated with pulmonary artery (PA) stiffness beyond the degree of severity of pulmonary hypertension (PH).
  
  
  BACKGROUND
  Increased PA stiffness has been associated with reduced survival in PH. The mechanisms for this association remain unclear.
  
  
  METHODS
  Right heart catheterization and cardiac magnetic resonance were performed within 1 week in 124 patients with known or suspected chronic PH. Pulmonary vascular resistance index (PVRI) and PA pressures were quantified from right heart catheterization. Cardiac magnetic resonance included standard biventricular cine sequences and main PA flow quantification with phase-contrast imaging. Indexes of PA stiffness (elasticity, distensibility, capacitance, stiffness index beta, and pulse pressure) were quantified combining right heart catheterization and cardiac magnetic resonance data. RV performance and adaptation were measured by RV ejection fraction, right ventricular mass index (RVMI), RV end-systolic volume index, and right ventricular stroke work index (RVSWI).
  
  
  RESULTS
  All indexes of PA stiffness were significantly correlated with measures of RV performance (Spearman rho coefficients ranging from -0.20 to 0.61, p < 0.05). Using multivariate regression analysis, PA elasticity, distensibility, and index beta were independently associated with all measures of RV performance after adjusting PVRI (p ≤ 0.024). PA capacitance was independently associated with RV ejection fraction, RVMI, and RVSWI (p < 0.05), whereas PA pulse pressure was associated with RVMI and RVSWI (p ≤ 0.027). Compared with PVRI, PA elasticity, distensibility, capacitance, and index beta explained 15% to 68% of the variability in RV ejection fraction, RVMI, and RV end-systolic volume index. Relative contributions of PA stiffness for RVSWI were 1.2× to 18.0× higher than those of PVRI.
  
  
  CONCLUSIONS
  PA stiffness is independently associated with the degree of RV dysfunction, dilation, and hypertrophy in PH. RV adaptation to chronic pressure overload is related not only to the levels of vascular resistance (steady afterload), but also to PA stiffness (pulsatile load).
authors.affiliation: Montefiore-Einstein Center for Heart and Vascular Care, Albert Einstein College of Medicine, Bronx, New York, New York, USA. gstevens@montefiore.org
authors.forename: Gerin R
authors.initials: GR
authors.lastname: Stevens
authors.forename: Ana
authors.initials: A
authors.lastname: Garcia-Alvarez
authors.forename: Sheila
authors.initials: S
authors.lastname: Sahni
authors.forename: Mario J
authors.initials: MJ
authors.lastname: Garcia
authors.forename: Valentin
authors.initials: V
authors.lastname: Fuster
authors.forename: Javier
authors.initials: J
authors.lastname: Sanz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006328:Cardiac Catheterization; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate; D006352:Heart Ventricles / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011651:Pulmonary Artery / Q000503:physiopathology*; D011669:Pulmonary Wedge Pressure; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013318:Stroke Volume; D059289:Vascular Stiffness; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D016278:Ventricular Function, Right; D017725:Ventricular Pressure; D055815:Young Adult