Implications of Exercise-Induced Pulmonary Arterial Hypertension
Purpose: To characterize the hemodynamic and ventilatory responses to exercise in a group of patients with unexplained dyspnea, increased risk for pulmonary arterial hypertension (PAH) and an elevated mean pulmonary artery pressure (mPAP) (>30mmHg) on exercise.
Methods: Thirty-seven symptomatic patients, at risk of PAH, and 20 healthy controls, underwent a cardiopulmonary exercise test and were assessed for quality of life (QoL). Patient subjects had a pulmonary artery catheter in situ during the exercise test.
Results: Seventeen subjects had exercise-induced pulmonary arterial hypertension (EIPAH), which we defined as mPAP <=25mmHg at rest, and mPAP >30mmHg and pulmonary artery wedge pressure <20mmHg on exercise. These subjects had reduced peak exercise cardiac output>(72+/-19% predicted). Further, compared with matched controls, subjects with EIPAH had reduced peak oxygen consumption (1.2+/-0.4 vs 1.7+/-0.5 L/min, p<0.05), an elevated ventilatory equivalent for carbon dioxide (41.0+/-7.3 vs 31.0+/-2.9, p<0.05) and reduced end tidal carbon dioxide tension (32.6+/-3.6 vs 39.4+/-2.7mmHg, p<0.05) at the anaerobic threshold. These exercise abnormalities were associated with impaired QoL (p<0.05).
Conclusion: Elevated pulmonary artery pressure on exercise can be associated with hemodynamic and ventilatory abnormalities typical of PAH, along with impaired exercise capacity and reduced QoL.