Assessment of compliance in pulmonary arterial hypertension

Abstract

The main mechanical feature of the pulmonary circulation is the ability to sustain low pressure levels even in the presence of high flow,1 thus being defined as a low resistance/high compliance system. Pulmonary hypertension is a multifactorial clinical condition mainly characterized by vascular remodelling that increases right ventricular afterload, eventually leading to ventricular dysfunction.2 Most of the clinical presentation and haemodynamic behaviour is directly related to the development and progression of right heart failure. Usually, this increase in afterload is described as the increase in pulmonary vascular resistance (PVR); indeed, PVR is one of the components of the right ventricular afterload. However, the total afterload is determined by three different vascular characteristics: resistance, compliance, and impedance.3 Whilst the concept of impedance is a little more difficult to transpose to the clinical setting, once it accounts the inertial properties of blood flow, resistance and compliance can be easily assimilated, even though, in the setting of pulmonary hypertension, most of the attention has been paid to the former only. … *Corresponding author. Tel: +331 46453135, Fax: +331 46453135, Email: rgrsz{at}uol.com.br