ABSTRACT
Clinical profile It is important to remember that the key underlying haemodynamic factor in any form of PH is the increase in the pulmonary vascular resistance in response to the remodelled pulmonary circulation. The primary driver of this pathological process, therefore, is largely clinically silent until the response is manifested by changes (both acute and chronic) in right ventricular function. As such, without treatment, to relieve chronic PAH, particularly in its severest form, patients typically develop progressive right ventricular hypertrophy, dilatation, and associated right ventricular dysfunction – see Figure 4.1.62-65 Without appropriate treatment, therefore, the right ventricle progressively fails, eventually resulting in death. As indicated, many of the pathological changes associated with PAH may not produce significant and readily indentifiable symptoms until the disease has progressed significantly (i.e. when right heart failure has developed as a consequence of increased pulmonary vascular resistance). In addition, the clinical profile of PAH may also be obscured by the underlying disease state (e.g. systemic sclerosis), particularly where other factors have a detrimental effect on exercise tolerance.
