References: Alonzo et al, 1987
D'Alonzo GE, Gianotti LA, Pohil RL, Reagle RR, DuRee SL, Fuentes F, Dantzker
Comparison of progressive exercise performance of normal subjects and
patients with primary pulmonary hypertension
Chest 1987 Jul; 92(1): p.57-62.
Divisions of Pulmonary Medicine and Cardiology, Department of Internal
Medicine, University of Texas Medical School, and Hermann Hospital, Houston.
The extent of exercise limitation and the mechanisms for that limitation in
11 patients with primary pulmonary hypertension (PPH) were studied by
progressive, upright cycle ergometry. All patients had a mean pulmonary artery
pressure of 30 mm Hg or higher (mean, 56 +/- 15), normal pulmonary function
testing, normal pulmonary capillary wedge pressure, and pulmonary angiography
consistent with the diagnosis. Rest and exercise data obtained from the patients
with PPh were compared with data obtained from 11 matched, sedentary control
subjects. Mean maximal oxygen consumption (VO2) was 13 +/- 4 ml/kg/min in the
PPH group compared with 28 +/- 7 ml/kg/min in the controls. At maximal VO2 the
minute ventilation (VE) was similar; however, the VE at any level of carbon
dioxide production (VCO2) during rest and exercise was significantly higher in
the PPH group. Maximal heart rate and oxygen pulse (VO2/heart rate) was
significantly higher in the control group (148 +/- 18 vs 180 +/- 24, and 6.3 +/-
2.2 vs 9.9 +/- 3.9, respectively). Anaerobic threshold occurred earlier during
progressive exercise in the PPH group and correlated positively with the maximal
oxygen pulse achieved in patients with PPH. In conclusion, patients with PPH
have severe exertional limitation due to cardiovascular factors with an
inability to maintain appropriate oxygen delivery to the body during exercise.
No respiratory impairment was recognized; however, an exaggerated ventilatory
response to exercise at any level of VCO2 was found.