Partitioning of pulmonary vascular resistance in primary pulmonary hypertension

J Am Coll Cardiol. 1998 May;31(6):1372-6. doi: 10.1016/s0735-1097(98)00091-6.


Objectives: This study sought to determine the site of increased pulmonary vascular resistance (PVR) in primary pulmonary hypertension by standard bedside hemodynamic evaluation.

Background: The measurement of pulmonary vascular pressures at several levels of flow (Q) allows the discrimination between active and passive, flow-dependent changes in mean pulmonary artery pressure (Ppa), and may detect the presence of an increased pulmonary vascular closing pressure. The determination of a capillary pressure (Pc') from the analysis of a Ppa decay curve after balloon occlusion allows the partitioning of PVR in an arterial and a (capillary + venous) segment. These approaches have not been reported in primary pulmonary hypertension.

Methods: Ppa and Pc' were measured at baseline and after an increase in Q induced either by exercise or by an infusion of dobutamine, at a dosage up to 8 microg/kg body weight per min, in 11 patients with primary pulmonary hypertension. Reversibility of pulmonary hypertension was assessed by the inhalation of 20 ppm nitric oxide (NO), and, in 6 patients, by an infusion of prostacyclin.

Results: At baseline, Ppa was 52+/-3 mm Hg (mean value+/-SE), Q 2.2+/-0.2 liters/min per m2, and Pc' 29+/-3 mm Hg. Dobutamine did not affect Pc' and allowed the calculation of an averaged extrapolated pressure intercept of Ppa/Q plots of 34 mm Hg. Inhaled NO had no effect. Prostacyclin decreased Pc' and PVR. Exercise increased Pc' to 40+/-3 mm Hg but did not affect PVR.

Conclusions: ns. These findings are compatible with a major increase of resistance and reactivity at the periphery of the pulmonary arterial tree.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-Antagonists / pharmacology
  • Adult
  • Aged
  • Dobutamine / pharmacology
  • Exercise / physiology
  • Female
  • Humans
  • Hypertension, Pulmonary / physiopathology*
  • Male
  • Middle Aged
  • Pulmonary Artery / physiology*
  • Pulmonary Circulation / physiology*
  • Regional Blood Flow
  • Vascular Resistance*


  • Adrenergic beta-Antagonists
  • Dobutamine