ABC | Volume 113, Nº3, September 2019

Review Article Calderado et al. Pulmonary hypertension Arq Bras Cardiol. 2019; 113(3):419-428 Table 1 – Classification of pulmonary hypertension 7,9 Group 1 Pulmonary Arterial Hypertension Group 2 Pulmonary hypertension due to left heart disease Group 3 Pulmonary hypertension due to Pulmonary Disease and/or Hypoxia Group 4 Chronic thromboembolic pulmonary hypertension and other diseases of pulmonary artery obstruction Group 5 Pulmonary hypertension with unclear multifactorial mechanisms Classification of pulmonary hypertension The current classification of PH takes into account data of clinical presentation, pathophysiology, anatomopathological findings and hemodynamic parameters, 7,9,11 and proposes a division into 5 different groups (Table 1). It should be highlighted that, since 2003, the terms “primary” and “secondary” PH are no longer listed in the WHO consensus. Group 1 Patients with PAH. These are the patients with idiopathic PAH, heritable PAH, associated with HIV infection, connective tissue disease, portal hypertension, drugs or congenital heart diseases. Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) are also categorized as Group 1. 14 Schistosomiasis-associated PH has a major epidemiological relevance in Brazil, and is included in this group. 15-18 InGroup 1 patients, the catheterization reveals pattern of pre-capillary HP (PAOP ≤ 15 mmHg), and does not show significant pulmonary heart disease or chronic thromboembolic HP. The histological findings are vasoconstriction, vascular remodelling with plexiform lesions and microthrombosis in the pulmonary vasculature. 19 Studies with specificmedication for the treatment of PH mainly comprise this group. Group 2 Patients with HP due to left heart disease: valvular disease, left ventricular diastolic or systolic dysfunction. These patients have hemodynamic patterns of post-capillary hypertension. In the cases where combined post-capillary PH with a pre‑capillary component is observed, the prognosis is worse than that for patients with isolated post-capillary PH. 20 The identification strategy of this hemodynamic profile can be sensitized by performing fluid challenge during catheterization. Elderly patients with metabolic syndrome, atrial fibrillation or changes in the left heart, revealed by echocardiography, have a high probability that their HP will be due to the post-capillary component. In these situations, if the PAOP is ≤ 15 mmHg and > 12 mmHg, a new fluid challenge during catheterization should be considered. 21 The administration of 500mL of saline solution within 5 minutes is recommended, being the post-capillary component assumed when the PAOP, measured immediately after the fluid challenge, is greater than 18 mmHg. 21 This is the most prevalent type of PH worldwide. 22 Group 3 Patients with HP due to pulmonary disease and/or hypoxia. For instance: chronic obstructive pulmonary disease, interstitial lung disease, obstructive sleep apnea, high altitude exposure. The hemodynamic pattern is that of pre-capillary HP. 9 Group 4 Patients with chronic thromboembolic pulmonary hypertension (CTEPH) or diseases of pulmonary artery obstruction such as arteritis, neoplasms, or congenital pulmonary artery stenosis, with hemodynamic pattern of pre‑capillary PH. 23 The aim of the treatment in this population is to restore blood flow to the obstructed vascular territories. Group 5 Patients with HP and unclear multifactorial mechanisms, as in the cases of renal failure, sarcoidosis, myeloproliferative disorders and hemolytic anemia. 7 Diagnostic evaluation of pulmonary hypertension The diagnostic suspicion is based on unspecified symptoms (dyspnea to effort and/or syncope), not always accompanied by signs suggestive of PH or right ventricular dysfunction (hyperphonesis of the second heart sound, tricuspid systolic murmur, jugular stasis, hepatomegaly and lower limb edema). Considering these findings, the non-invasive test of choice to begin the investigation is the transthoracic echocardiography. 19 The interval between the symptom onset and the diagnosis of PH is about two years, which hinders early treatment. 7 The investigation should begin by searching for the most frequent causal factors: left heart disease, lung disease or pulmonary thromboembolism. Only after excluding these conditions, should the presence of PAH be considered, as proposed in the algorithm (Figure 1). CHEST X-Ray It can show prominence of the pulmonary artery trunk, as well as of the right (> 16 mm) and/or left (> 18 mm) branches, increased right chambers (bulging of the right mediastinal contour, boot shaped heart and filling of retrosternal space). 24 These changes are usually more marked only in advanced stages of the disease. Electrocardiography Traditionally, the electrocardiography shows signs of overload in the right chambers – axis shift to the right and P-wave pulmonale (p ≥ 2.5 mm in DII); as in the X-ray, the electrocardiographic changes are more evident in the stages when there is cardiac structure repercussion. In up to 13% of the cases, the EGC is normal. 25 420