Perioperative Management of Pulmonary Hypertension

Pulmonary hypertension is the manifestation of a disorder of the pulmonary vascular bed, which results in obstruction of pulmonary blood flow. Although many different causes exist, hypertension in the pulmonary circulation is the result of increased vascular resistance, increased vascular bed flow, or both. The signs and symptoms of pulmonary hypertension are nonspecific and subtle. Left untreated, patients will experience progressive symptoms of dyspnea and right heart failure culminating in a markedly curtailed survival [Gaine, 2000]. Idiopathic pulmonary arterial hypertension is a relatively rare disease of unknown cause [Lloyd et al, 1995]; however, in the perioperative arena the majority of patients encountered with pulmonary hypertension have acquired it secondary to a cardiac or a pulmonary disease process. Left sided ventricular or atrial disease and left sided valvular heart disease are common causes of pulmonary hypertension. Both of these conditions elevate left atrial pressure and passively increase pulmonary venous pressure, pulmonary artery pressure (PAP), and pulmonary vascular resistance (PVR). Multiple respiratory diseases lead to the development of pulmonary hypertension via a hypoxia-induced vasoconstriction [Phillips et al, 1999]. Regardless of causation, all pathways lead to an altered vascular endothelium and smooth muscle function through cellular remodeling [MacLean, 1999; Tuder et al, 2001]. This results in increased vascular contractility or lack of vascular relaxation in response to various endogenous vasodilator substances. Detailed discussion of the pathology, pathophysiology, evaluation and treatment are provided elsewhere in this text and via consensus statements from the American College of Cardiology/American Heart Association. [McLaughlin et al, 2009]