Assessing disease state in the pulmonary vasculature in clinical practice and research

Abstract

The pulmonary circulation is normally a high-flow, low-resistance, low-pressure system that carries blood to the pulmonary microcirculation where gas exchange occurs. In pulmonary arterial hypertension (PAH), the vasculature becomes less compliant as a result of vascular smooth muscle cell proliferation and hypertrophy, and endothelial cell proliferation resulting in lumen obliteration. This change results in a highly resistant low compliance system, which places an undue load on the right ventricle, eventually leading to right heart failure. The timeline of events that result in an obliterative vascular remodeling parallels the evolution of right ventricular (RV) remodeling from a normal to a decompensated state. Patients commonly present with non- specific symptoms of exercise limitation and dyspnea. Once a diagnosis is made and patients are started on therapy clinicians and researchers face the challenge of how to serially and objectively follow patients to gauge treatment response. There are a number of approaches available and being developed to assess response to therapy. Consequently there is a need to analyze current techniques and identify the future techniques that might be useful to guide management of PAH.