The Right Ventricle in Pulmonary Hypertension

The main cause of morbidity and mortality in pulmonary arterial hypertension (PAH) is not injury to the lung, but rather progressive right ventricular (RV) dysfunction. Although the pulmonary vasculopathy associated with PAH can impair gas exchange, patients with PAH suffer most from the inability to adequately increase cardiac output, especially during exercise. RV dysfunction in PAH is typically viewed as a secondary event, an unavoidable consequence of the progressive rise in pulmonary vascular resistance. However, the RV response to increased pulmonary afterload varies considerably between individuals, and those variations may significantly impact functional capacity and survival. This chapter explores the adaptive and maladaptive responses of the RV to elevated pulmonary arterial pressure (PAP) and the cellular and molecular mechanisms responsible for them. The effect of RV overload on left ventricular (LV) function is also reviewed. New techniques used to monitor RV function at baseline and in response to therapy are presented. Finally, an overview of the management of RV failure in PAH is provided along with a discussion of future therapeutic approaches.