Pulmonary vascular distensibility predicts aerobic capacity in healthy individuals.
It has been suggested that shallow slopes of mean pulmonary artery pressure (MPPA)–cardiac output (Q) relationships and pulmonary transit of agitated contrast during exercise may be associated with a higher maximal aerobic capacity V(O(2)max). If so, individuals with a higher V(O(2)max) could also exhibit a higher pulmonary vascular distensibility and increased pulmonary capillary blood volume during exercise. Exercise stress echocardiography was performed with repetitive injections of agitated contrast and measurements of MPPA, Q and lung diffusing capacities for carbon monoxide (D(L,CO)) and nitric oxide (D(L,CO)) in 24 healthy individuals. A pulmonary vascular distensibility coefficient α was mathematically determined from the slight natural curvilinearity of multipoint MPPA–Q plots. Membrane (D(m)) and capillary blood volume (V(c)) components of lung diffusing capacity were calculated. Maximal exercise increased MPPA, cardiac index (CI), D(L,CO) and (D(L,NO). The slope of the linear best fit of MPPA–CI was 3.2 ± 0.5 mmHg min l(-1) m(2) and α was 1.1 ± 0.3% mmHg(-1). A multivariable analysis showed that higher α and greater V(c) independently predicted V(O(2)max). All individuals had markedly positive pulmonary transit of agitated contrast at maximal exercise, with increases proportional to increases in pulmonary capillary pressure and V(c). Pulmonary transit of agitated contrast was not related to pulse oximetry arterial oxygen saturation. Therefore, a more distensible pulmonary circulation and a greater pulmonary capillary blood volume are associated with a higher V(O(2)max) in healthy individuals. Agitated contrast commonly transits through the pulmonary circulation at exercise, in proportion to increased pulmonary capillary pressures.
Laboratory of Cardiorespiratory Physiology, Faculté des Sciences de la Motricité, Université Libre de Bruxelles, Brussels, Belgium. slaland@uwo.ca
Sophie
S
Lalande
Patrick
P
Yerly
Vitalie
V
Faoro
Robert
R
Naeije
D000328:Adult; D001810:Blood Volume / Q000502:physiology; D003287:Contrast Media; D015150:Echocardiography, Doppler; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D011651:Pulmonary Artery / Q000502:physiology; D011652:Pulmonary Circulation / Q000502:physiology*; D011653:Pulmonary Diffusing Capacity / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology; D055815:Young Adult
D003287:Contrast Media