title: The linear relationship between systolic pulmonary artery pressure and mean pulmonary artery pressure is maintained regardless of autonomic or rhythm disturbances.
abstract: BACKGROUND
  In the pulmonary circulation, there is a linear relationship between systolic pulmonary arterial pressure (SPAP) and mean pulmonary arterial pressure (MPAP). The aim of this study was to determine the passive or active nature of this mechanism by exploring the relationship in patients with and without autonomic rhythm control of the heart and pulmonary circulation.
  
  
  METHODS
  Pulmonary arterial pressure recordings from non-transplanted patients and patients with heart transplants or double lung transplants were retrospectively reviewed. The relationships between systolic, diastolic, and mean pulmonary arterial pressures were explored.
  
  
  RESULTS
  A linear relationship was observed between the SPAP and MPAP, whether patients were paced (MPAP = 0.56 SPAP + 3.86 mmHg, r (2)  = 0.889), treated with inotropes (MPAP = 0.55 SPAP + 5.52 mmHg, r (2)  = 0.947) or pulmonary vasodilators (MPAP = 0.58 SPAP + 2.41 mmHg, r (2)  = 0.927), were exercising (MPAP = 0.61 SPAP + 1.18 mmHg, r (2)  = 0.967), had a heart transplant (MPAP = 0.66 SPAP +0.87 mmHg, r (2)  = 0.849), a double lung transplant (MPAP = 0.7 SPAP +0.48 mmHg, r (2)  = 0.915), or no intervention (MPAP = 0.59 SPAP +1.75 mmHg, r (2)  = 0.937).
  
  
  CONCLUSIONS
  We demonstrate that the linear relationship between SPAP and MPAP remains in several situations. Therefore, we conclude that the underlying mechanism is a passive consequence of the elastic properties of the cardiopulmonary unit.
authors.affiliation: Department of Cardiac Surgery, Université Libre de Bruxelles, Hôpital Académique Erasme, 808 Route de Lennick, B-1070, Brussels, Belgium. frederic.vanden.eynden@erasme.ulb.ac.be.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Vanden Eynden
authors.affiliation: Research Center of Biostatistics, Epidemiology and Clinical Research, School of Public Health, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Judith
authors.initials: J
authors.lastname: Racapé
authors.affiliation: Anesthesiology Departments, Université Libre de Bruxelles, Hôpital Académique Erasme, Brussels, Belgium.
authors.forename: Jame
authors.initials: J
authors.lastname: Vincent
authors.affiliation: Cardiology, Université Libre de Bruxelles, Hôpital Académique Erasme, Brussels, Belgium.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Vachiéry
authors.affiliation: Laboratory of Experimental Cardiac Surgery, University Hospital of Gent, Gent, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Bové
authors.affiliation: Department of Cardiac Surgery, Université Libre de Bruxelles, Hôpital Académique Erasme, 808 Route de Lennick, B-1070, Brussels, Belgium.
authors.forename: Guido
authors.initials: G
authors.lastname: Van Nooten
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology*; D001341:Autonomic Nervous System / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods; D003198:Computer Simulation; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D016027:Heart Transplantation; D006801:Humans; D016014:Linear Models; D016040:Lung Transplantation; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011669:Pulmonary Wedge Pressure / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013599:Systole
keywords: Pulmonary artery pressure; Pulmonary circulation physiopathology; Transplantation