title: Right ventriculo-arterial coupling in pulmonary hypertension: a magnetic resonance study.
abstract: OBJECTIVE
  To quantify right ventriculo-arterial coupling in pulmonary hypertension by combining standard right heart catheterisation (RHC) and cardiac magnetic resonance (CMR) and to estimate it non-invasively with CMR alone.
  
  
  METHODS
  Cross-sectional analysis in a retrospective cohort of consecutive patients.
  
  
  METHODS
  Tertiary care centre.
  
  
  METHODS
  139 adults referred for pulmonary hypertension evaluation.
  
  
  METHODS
  CMR and RHC within 2 days (n=151 test pairs).
  
  
  METHODS
  Right ventriculo-arterial coupling was quantified as the ratio of pulmonary artery (PA) effective elastance (E(a), index of arterial load) to right ventricular maximal end-systolic elastance (E(max), index of contractility). Right ventricular end-systolic volume (ESV) and stroke volume (SV) were obtained from CMR and adjusted to body surface area. RHC provided mean PA pressure (mPAP) as a surrogate of right ventricular end-systolic pressure, pulmonary capillary wedge pressure (PCWP) and pulmonary vascular resistance index (PVRI). E(a) was calculated as (mPAP - PCWP)/SV and E(max) as mPAP/ESV.
  
  
  RESULTS
  E(a) increased linearly with advancing severity as defined by PVRI quartiles (0.19, 0.50, 0.93 and 1.63 mm Hg/ml/m(2), respectively; p<0.001 for trend) whereas E(max) increased initially and subsequently tended to decrease (0.52, 0.67, 0.54 and 0.56 mm Hg/ml/m(2); p=0.7). E(a)/E(max) was maintained early but increased markedly with severe hypertension (0.35, 0.72, 1.76 and 2.85; p<0.001), indicating uncoupling. E(a)/E(max) approximated non-invasively with CMR as ESV/SV was 0.75, 1.17, 2.28 and 3.51, respectively (p<0.001).
  
  
  CONCLUSIONS
  Right ventriculo-arterial coupling in pulmonary hypertension can be studied with standard RHC and CMR. Arterial load increases with disease severity whereas contractility cannot progress in parallel, leading to severe uncoupling.
authors.affiliation: The Zena and Michael A Wiener Cardiovascular Institute, Mount Sinai School of Medicine, New York, USA. javier.sanz@mssm.edu
authors.forename: Javier
authors.initials: J
authors.lastname: Sanz
authors.forename: Ana
authors.initials: A
authors.lastname: García-Alvarez
authors.forename: Leticia
authors.initials: L
authors.lastname: Fernández-Friera
authors.forename: Ajith
authors.initials: A
authors.lastname: Nair
authors.forename: Jesús G
authors.initials: JG
authors.lastname: Mirelis
authors.forename: Simonette T
authors.initials: ST
authors.lastname: Sawit
authors.forename: Sean
authors.initials: S
authors.lastname: Pinney
authors.forename: Valentin
authors.initials: V
authors.lastname: Fuster
mesh_terms: D006328:Cardiac Catheterization; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis* / Q000503:physiopathology; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009200:Myocardial Contraction / Q000502:physiology*; D011379:Prognosis; D011651:Pulmonary Artery / Q000503:physiopathology; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016278:Ventricular Function, Right