Pulmonary hypertension (PH) is an end result of a diverse array of complex clinical conditions that invoke hemodynamic and pathophysiological changes in the pulmonary vasculature. Many patients’ symptoms begin with dyspnea on exertion for which screening tests such as chest roentgenograms and more definitive noninvasive tests such as CT scans are ordered initially. It is imperative that clinicians are cognizant of subtle clues on these imaging modalities that alert them to the possibility of PH. These clues may serve as a stepping stone towards more advanced noninvasive (echocardiogram) and invasive (right heart catheterization) testing. On the CT scan, the signs are classified into mediastinal and lung parenchymal abnormalities. In addition to suspecting the diagnosis of PH, this paper provides a pictorial essay to guide health care professionals in identifying the etiology of PH. This paper also provides concrete definitions, wherever possible, of what constitutes abnormalities in PH, such as dilated pulmonary arteries, pruning of vessels, and increased thickness of free wall of the right ventricle. The sensitivities and specificities of each sign are enumerated. The common radiographic and clinical features of many different etiologies of PH are tabulated for the convenience of the readers. Some newer imaging modalities such as dual-energy CT of the chest that hold promise for the future are also described.
Exercise stress testing of the pulmonary circulation for the diagnosis of latent or early-stage pulmonary hypertension (PH) is gaining acceptance. There is emerging consensus to define exercise-induced PH by a mean pulmonary artery pressure > 30 mm Hg at a cardiac output 3 Wood units at maximum exercise, in the absence of PH at rest. Exercise-induced PH has been reported in association with a bone morphogenetic receptor-2 gene mutation, in systemic sclerosis, in left heart conditions, in chronic lung diseases, and in chronic pulmonary thromboembolism. Exercise-induced PH is a cause of decreased exercise capacity, may precede the development of manifest PH in a proportion of patients, and is associated with a decreased life expectancy. Exercise stress testing of the pulmonary circulation has to be dynamic and rely on measurements of the components of the pulmonary vascular equation during, not after exercise. Noninvasive imaging measurements may be sufficiently accurate in experienced hands, but suffer from lack of precision, so that invasive measurements are required for individual decision-making. Exercise-induced PH is caused either by pulmonary vasoconstriction, pulmonary vascular remodeling, or by increased upstream transmission of pulmonary venous pressure. This differential diagnosis is clinical. Left heart disease as a cause of exercise-induced PH can be further ascertained by a pulmonary artery wedge pressure above or below 20 mm Hg at a cardiac output < 10 L/min or a pulmonary artery wedge pressure-flow relationship above or below 2 mm Hg/L/min during exercise.
In this trial, 261 patients with chronic thromboembolic pulmonary hypertension were assigned to placebo or to the soluble guanylate cyclase stimulator riociguat. At 16 weeks, riociguat had significantly improved the 6-minute walk distance and pulmonary vascular resistance. Chronic thromboembolic pulmonary hypertension is characterized by obstruction of the pulmonary vasculature by residual organized thrombi, 1 leading to increased pulmonary vascular resistance, progressive pulmonary hypertension, and right ventricular failure. 2 , 3 Patients with chronic thromboembolic pulmonary hypertension have a poor prognosis unless they receive treatment early. 4 Pulmonary endarterectomy is the standard treatment for chronic thromboembolic pulmonary hypertension and is the only potentially curative treatment. 5 However, surgery is not an option for all patients; some patients are ineligible for surgery owing to the occlusion of distal vessels or coexisting conditions, some decline surgery, and some do not have access to expert surgical . . .
SUMMARY POINTS Pulmonary hypertension has many causes so prognoses and treatments vary The condition is diagnosed by systematically evaluating the breathless patient and screening patients at high risk Patients at high risk of severe and treatable pulmonary hypertension include those with systemic sclerosis, portal hypertension, congenital heart disease, and previous pulmonary embolism Specialist centres provide access to tailored investigative and treatment pathways and support networks for patients Patients with severe pulmonary hypertension can deteriorate rapidly—do not delay referral to perform specialist investigations Only selected patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension benefit from interventions directed at pulmonary vasculature; for most patients treatment is aimed at the underlying condition