PRESCRIBING IN PRACTICE ■ P ulmonary hypertension refers to increased pressure in the pulmonary arterial circulation. The pulmonary circulation has to accommodate the entire cardiac output in each cardiac cycle, and evolution has adapted to this by making it a low-pressure high-flow system. However, pathology can affect both the arterial and venous components of this system. Pulmonary venous hypertension mainly refers to diseases that result in elevated venous pressure and occurs mainly from mitral valve and left-sided heart disease; these will not be discussed in this article. As a result of greater understanding of the molecular and cellular pathways involved in the pathobiology of pulmonary arterial hypertension (PAH), novel and exciting treatments have become available to treat this condition. These new drugs represent a huge step forward in the treatment of this universally fatal disease in that they allow improvement in quality of life and survival; however, they do not as yet offer a cure. Definition PAH is defined by consensus as a mean pulmonary artery pressure of above 25mmHg in the setting of a normal or reduced cardiac output, with a normal pulmonary capillary wedge pressure (PCWP) and elevated pulmonary vascular resistance (PVR). The normal PCWP is required to exclude the presence of significant left heart disease and pulmonary venous hypertension. As a result, the diagnosis of pulmonary hypertension requires invasive right-heart catheterisation. Classification Pulmonary hypertension is an umbrella term that refers simply to elevated pressure in the pulmonary vasculature. There are a wide variety of causes of this and the 2008 WHO conference in Dana Point attempted to clarify and organise these into a more defined classification (see Figure 2). 1 This article will focus on PAH (group 1).

No abstract

Guidelines summarize and evaluate all available evidence on a particular issue at the time of the writing process, with the aim of assisting health professionals in selecting the best management strategies for an individual patient with a given condition, taking into account the impact on outcome, as well as the risk–benefit ratio of particular diagnostic or therapeutic means. Guidelines and recommendations should help health professionals to make decisions in their daily practice. However, the final decisions concerning an individual patient must be made by the responsible health professional(s) in consultation with the patient and caregiver as appropriate.

Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure ≥ 25 mm Hg at rest, measured during right heart catheterization. There is still insufficient evidence to add an exercise criterion to this definition. The term pulmonary arterial hypertension (PAH) describes a subpopulation of patients with PH characterized hemodynamically by the presence of pre-capillary PH including an end-expiratory pulmonary artery wedge pressure (PAWP) ≤ 15 mm Hg and a pulmonary vascular resistance >3 Wood units. Right heart catheterization remains essential for a diagnosis of PH or PAH. This procedure requires further standardization, including uniformity of the pressure transducer zero level at the midthoracic line, which is at the level of the left atrium. One of the most common problems in the diagnostic workup of patients with PH is the distinction between PAH and PH due to left heart failure with preserved ejection fraction (HFpEF). A normal PAWP does not rule out the presence of HFpEF. Volume or exercise challenge during right heart catheterization may be useful to unmask the presence of left heart disease, but both tools require further evaluation before their use in general practice can be recommended. Early diagnosis of PAH remains difficult, and screening programs in asymptomatic patients are feasible only in high-risk populations, particularly in patients with systemic sclerosis, for whom recent data suggest that a combination of clinical assessment and pulmonary function testing including diffusion capacity for carbon monoxide, biomarkers, and echocardiography has a higher predictive value than echocardiography alone.