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Cardiovascular response to exercise in Pulmonary Arterial Hypertension patients: the role of electrical impedance tomography and natriuretic peptides

Grant number: 07/03762-8
Support Opportunities:Regular Research Grants
Duration: June 01, 2008 - November 30, 2010
Field of knowledge:Health Sciences - Medicine - Medical Clinics
Principal Investigator:Rogério de Souza
Grantee:Rogério de Souza
Host Institution: Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
Associated researchers:Carlos Viana Poyares Jardim

Abstract

Idiopathic pulmonary arterial hypertension (IPAH) is a rare disease of unknown etiology in which there is progressive raise in pulmonary pressures leading to right ventricular failure. Despite considerable treatment advances in the last decade, survival rates are still unsatisfactory. Considering that in pulmonary hypertension there is a loss of cardiovascular adaptation to exercise over the course of the disease, a clear limitation of surrogate markers lies on the fact that most of them are obtained at rest. It is believed that there is a need for the development of techniques that may reflect cardiovascular adaptation during exercise in patients with IPAH, in order to establish alternative endpoints for treatment response and prognosis. Electrical impedance tomography (EIT) produces a real-time regional perfusion image, reflecting the possible heterogeneous pulmonary involvement of the vascular bed in IPAH patients. Natriuretic peptides obtained during exercise may also contribute to a better understanding of ventricular performance in patients with increased pulmonary vascular resistance. Our main objective is to assess the BNP production curve during an incremental exercise test under the perspective of the hemodynamic behavior and to assess the pulmonary blood flow pattern during this protocol using EIT. There will be enrolled in the study 30 consecutive IPAH patients (18-50 y-o), without any specific treatment and that are having a right heart catheterization (RHC) requested by their primary physician (routine diagnosis RHC). Exclusion criteria: pregnancy and current exclusion criteria adopted by the American Thoracic Society as contraindications for exercise test in patients without IPAH. Patients will perform a six minute walk test, answer the SF-36 questionnaire and will have a baseline RHC, as well as a rest EIT pulmonary perfusion map. After baseline hemodynamics, all patients will perform an incremental exercise test protocol, in supine position, with a cycle-ergometer adapted to the hemodynamic bed. To each step of the protocol, hemodynamic data and EIT images are to be recorded; blood samples for BNP measurement will be drawn in 30, 60 and 90 minutes after maximum effort. BNP levels and variations in pulmonary perfusion assessed by EIT will be correlated with hemodynamic variation using the Pearson correlation test. These data will also be correlated to baseline clinical and functional data. We believe that this study may provide useful data concerning the dynamic behavior of biomarkers that will convey a better understanding of the cardiovascular response to exercise in a condition in which there is a heterogeneous pulmonary vascular involvement. Dynamic evaluation may be a better tool to be used in the future for evaluation of specific treatment response and prognosis. (AU)

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