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1 Introduction
Pulmonary arterial hypertension (PAH) is a disorder of the pulmonary circulation
and it is defined by hemodynamic criteria: a mean pulmonary arterial pressure
(PAPm) ≥ 25 mmHg at rest, a pulmonary artery wedge pressure < 15 mmHg and a
pulmonary vascular resistance (PVR) > =3 Wood units [ 1 ]. It is characterized by a
gradual increase in PVR reflecting the progressive obliteration of small pulmonary
arteries. Consequently, PAH increases the right ventricle (RV) afterload, resulting
in maladaptive remodeling and failure, leading to premature death [ 2 ]. PAH may
arise in association with a broad range of diseases and its prevalence is estimated to
be 10–15 cases per million with a mortality rate of 15% per year but information
may differ through registries [ 1 , 3 ]. Regardless of the etiology, symptoms are non-
specific and mainly reflect the deterioration of the coupling between the RV and
pulmonary circulation. They can include shortness of breath, fatigue, weakness,
angina and syncope [ 1 ]. Over the past two decades, advances in PAH-specific thera-
pies have improved survival and slowed disease progression [ 4 – 6 ]. However, most
patients remain symptomatic with significant exercise intolerance, reduced quality
of life and still have an ominous prognosis.
Exercise training (ExT) has preventive and therapeutic effects in several chronicdiseases [ 7 , 8 ] but only recently it started to be recognized as safe and beneficial in
PAH. In fact, PAH treatment guidelines used to advise that any physical activity
should be limited as it could aggravate the disease progression and increase the risk
of sudden cardiac death [ 9 ]. However, accumulating evidence suggests a positive
effect of supervised ExT in functional capacity and quality of life, when added to
the best standard of care with approved medications. Importantly, ExT seems to
have a reassuring safety profile [ 10 , 11 ]. The physiological mechanisms that explain
the increased exercise tolerance attained by PAH patients enrolled in structured ExT
programs are still unclear. Beneficial changes in cardiac output, PVR, chronotropic
response to exercise and peripheral skeletal muscle have all been described [ 10 ].
Accordingly, current guidelines now recommend that PAH patients should be
encouraged to be active within symptom limits and, when physically deconditioned,
A.F. Silva • A. Leite-Moreira • T. Henriques-Coelho
Department of Surgery and Physiology, Faculty of Medicine University of Porto,
Porto 4200-319, Portugal
R. Ferreira
Chemistry Department, University of Aveiro,
Campus Universitário de São Tiago, Aveiro 3810-193, Portugal
J.A. Duarte
Center of Physical Activity, Health and Leisure (CIAFEL), Faculty of Sport University of
Porto, R. Dr. Plácido da Costa 91, Porto 4200-450, Portugal
D. Moreira-Gonçalves et al.