Pulmonary Capillary Wedge Pressure Augments Right Ventricular Pulsatile Loading
Background—Right ventricular (RV) failure from increased pulmonary vascular loading is a major cause of morbidity and mortality, yet its modulation by disease remains poorly understood. We tested the hypotheses that, unlike the systemic circulation, pulmonary vascular resistance (RPA) and compliance (CPA) are consistently and inversely related regardless of age, pulmonary hypertension (PH), or interstitial fibrosis, and that this relation may be changed by elevated pulmonary capillary wedge pressure (PCWP), augmenting RV pulsatile load.
Methods and Results—Several large clinical databases with right heart/pulmonary catheterization data were analyzed to determine the RPA-CPA relationship with PH, pulmonary fibrosis, patient age, and varying PCWP. Patients with suspected or documented PH (n=1009) and normal PCWP displayed a consistent RPA-CPA hyperbolic (inverse) dependence; CPA=0.564/(0.047+RPA), with a near constant resistance-compliance product (RC) (0.48±0.17 seconds). In the same patients, the systemic RC was highly variable. Severe pulmonary fibrosis (n=89) did not change the RPA-CPA relation. Increasing patient age led to a very small though statistically significant change in the relation. However, elevation of the PCWP (n=8142) had a larger impact, significantly lowering CPA for any RPA, and negatively correlating RC (p<0.0001).
Conclusions—PH and pulmonary fibrosis do not significantly change the hyperbolic dependence between RPA and CPA, while patient age has only minimal affects. This fixed relationship helps explain the difficulty of reducing total RV afterload by therapies that have modest impact on mean RPA. Higher PCWP appears to enhance net RV afterload by elevating pulsatile, relative to resistive load, and may contribute to RV dysfunction.
- heart failure
- pulmonary hypertension
- pulmonary vascular changes
- right ventricle
- ventricular/vascular coupling hemodynamics
- Received June 22, 2011.
- Accepted November 17, 2011.
- Copyright © 2011, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited