In 1998, a clinical classification of pulmonary hypertension (PH) was established, categorizing PH into groups which share similar pathological and hemodynamic characteristics and therapeutic approaches. During the 5th World Symposium held in Nice, France, in 2013, the consensus was reached to maintain the general scheme of previous clinical classifications. However, modifications and updates especially for Group 1 patients (pulmonary arterial hypertension [PAH]) were proposed. The main change was to withdraw persistent pulmonary hypertension of the newborn (PPHN) from Group 1 because this entity carries more differences than similarities with other PAH subgroups. In the current classification, PPHN is now designated number 1. Pulmonary hypertension associated with chronic hemolytic anemia has been moved from Group 1 PAH to Group 5, unclear/multifactorial mechanism. In addition, it was decided to add specific items related to pediatric pulmonary hypertension in order to create a comprehensive, common classification for both adults and children. Therefore, congenital or acquired left-heart inflow/outflow obstructive lesions and congenital cardiomyopathies have been added to Group 2, and segmental pulmonary hypertension has been added to Group 5. Last, there were no changes for Groups 2, 3, and 4.

The diagnosis and assessment of pulmonary arterial hypertension is a rapidly evolving area, with changes occurring in the definition of the disease, screening and diagnostic techniques, and staging and follow-up assessment. The definition of pulmonary hypertension has been simplified, and is now based on currently available evidence. There has been substantial progress in advancing the imaging techniques and biomarkers used to screen patients for the disease and to follow up their response to therapy. The importance of accurate assessment of right ventricular function in following up the clinical course and response to therapy is more fully appreciated. As new therapies are developed for pulmonary arterial hypertension, screening, prompt diagnosis, and accurate assessment of disease severity become increasingly important. A clear definition of pulmonary hypertension and the development of a rational approach to diagnostic assessment and follow-up using both conventional and new tools will be essential to deriving maximal benefit from our expanding therapeutic armamentarium.

According to current guidelines, pulmonary arterial hypertension (PAH) is diagnosed when mean pulmonary arterial pressure (Ppa) exceeds 25 mmHg at rest or 30 mmHg during exercise. Issues that remain unclear are the classification of Ppa values ,25mmHg and whether Ppa .30 mmHg during exercise is always pathological.We performed a comprehensive literature review and analysed all accessible data obtained by right heart catheter studies from healthy individuals to determine normal Ppa at rest and during exercise. Data on 1,187 individuals from 47 studies in 13 countries were included. Data were stratified for sex, age, geographical origin, body position and exercise level.Ppa at rest was 14.0¡3.3 mmHg and this value was independent of sex and ethnicity. Resting Ppa was slightly influenced by posture (supine 14.0¡3.3 mmHg, upright 13.6¡3.1 mmHg) and age (,30 yrs: 12.8¡ 3.1mmHg; 30-50 yrs: 12.9¡3.0 mmHg; o50 yrs: 14.7¡4.0 mmHg). Ppa during exercise was dependent on exercise level and age. During mild exercise, Ppa was 19.4¡4.8 mmHg in subjects aged ,50 yrs compared with 29.4¡8.4 mmHg in subjects o50 yrs (p,0.001).In conclusion, while Ppa at rest is virtually independent of age and rarely exceeds 20 mmHg, exercise Ppa is age-related and frequently exceeds 30 mmHg, especially in elderly individuals, which makes it difficult to define normal Ppa values during exercise.

Pulmonary arterial hypertension (PAH) is diagnosed by various investigations that are essential for making the diagnosis, and by additional tests to clarify the category of pulmonary hypertension (PH). A diagnostic algorithm can guide the evaluation of PH, but like all guidelines the algorithm can be modified according to specific clinical circumstances. Most patients are diagnosed as the result of an evaluation of symptoms, whereas others are diagnosed during screening of asymptomatic populations at risk. Right heart catheterization (RHC) must be performed in patients with suspected PH to establish the diagnosis and document pulmonary hemodynamics. Before initiation of medical therapy, assessment of acute vasoreactivity (during catheterization) is necessary to determine the appropriate therapy for an individual patient. An acute response is generally defined as a decrease in mean pulmonary arterial pressure of at least 10 mm Hg with the mean pulmonary arterial pressure decreasing to 40 mm Hg or below, accompanied by a normal or high cardiac output. After PAH is diagnosed, disease severity should be assessed in order to accurately determine risk:benefit profiles for various therapeutic options. Useful tools to predict outcome include functional class, exercise capacity, pulmonary hemodynamics, acute vasoreactivity, right ventricular function, as well as brain natriuretic peptide, endothelin-1, uric acid, and troponin levels. Repeating these tests serially on treatment is useful for monitoring the response to a given therapy. Close follow-up at a center specializing in management of PH is recommended, with careful periodic reassessment and adjustment of therapy.

Pulmonary hypertension (PH) frequently complicates the course of patients with various forms of chronic lung disease (CLD). CLD-associated PH (CLD-PH) is invariably associated with reduced functional ability, impaired quality of life, greater oxygen requirements and an increased risk of mortality. The aetiology of CLD-PH is complex and multifactorial, with differences in the pathogenic sequelae between the diverse forms of CLD. Haemodynamic evaluation of PH severity should be contextualised within the extent of the underlying lung disease, which is best gauged through a combination of physiological and imaging assessment. Who, when, if and how to screen for PH will be addressed in this article, as will the current state of knowledge with regard to the role of treatment with pulmonary vasoactive agents. Although such therapy cannot be endorsed given the current state of findings, future studies in this area are strongly encouraged.