The previous definition of exercise pulmonary hypertension (PH) with a mean pulmonary artery pressure (mPAP) >30 mmHg was abandoned because healthy individuals can exceed this threshold at high cardiac output (CO). We hypothesised that incorporating assessment of the pressure–flow relationship using the mPAP/CO ratio,i.e.total pulmonary resistance (TPR), might enhance the accuracy of diagnosing an abnormal exercise haemodynamic response.Exercise haemodynamics were evaluated in 169 consecutive subjects with normal resting mPAP ≤20 mmHg. Subjects were classified into controls without heart or lung disease (n=68)versuspatients with pulmonary vascular disease (PVD) (n=49) and left heart disease (LHD) (n=52).TPR and mPAP at maximal exercise produced diagnostic accuracy with area under the receiver operating curve of 0.99 and 0.95, respectively, for discriminating controlsversuspatients with PVD and LHD. The old criterion of mPAP >30 mmHg had sensitivity of 0.98 but specificity of 0.77. Combining maximal mPAP >30 mmHg and TPR >3 mmHg·min·L⁻¹retained sensitivity at 0.93 but improved specificity to 1.0. The accuracy of the combined criteria was high across different age groups, sex, body mass index and diagnosis (PVD or LHD).Combining mPAP >30 mmHg and TPR >3 mmHg·min·L⁻¹is superior to mPAP >30 mmHg alone for defining a pathological haemodynamic response of the pulmonary circulation during exercise.

We tested whether the kinetics of systemic O₂ delivery (Q̇aO₂) at exercise start was faster than that of lung O₂ uptake (V̇o₂), being dictated by that of cardiac output (Q̇), and whether changes in Q̇ would explain the postulated rapid phase of the V̇o₂ increase. Simultaneous determinations of beat-by-beat (BBB) Q̇ and Q̇aO₂, and breath-by-breath V̇o₂ at the onset of constant load exercises at 50 and 100 W were obtained on six men (age 24.2 ± 3.2 years, maximal aerobic power 333 ± 61 W). V̇o₂ was determined using Grønlund's algorithm. Q̇ was computed from BBB stroke volume (Q_st, from arterial pulse pressure profiles) and heart rate ( f_h, electrocardiograpy) and calibrated against a steady-state method. This, along with the time course of hemoglobin concentration and arterial O₂ saturation (infrared oximetry) allowed computation of BBB Q̇aO₂. The Q̇, Q̇aO₂ and V̇o₂ kinetics were analyzed with single and double exponential models. f_h, Q_st, Q̇, and V̇o₂ increased upon exercise onset to reach a new steady state. The kinetics of Q̇aO₂ had the same time constants as that of Q̇. The latter was twofold faster than that of V̇o₂. The V̇o₂ kinetics were faster than previously reported for muscle phosphocreatine decrease. Within a two-phase model, because of the Fick equation, the amplitude of phase I Q̇ changes fully explained the phase I of V̇o₂ increase. We suggest that in unsteady states, lung V̇o₂ is dissociated from muscle O₂ consumption. The two components of Q̇ and Q̇aO₂ kinetics may reflect vagal withdrawal and sympathetic activation.

A resting mean pulmonary artery pressure (mPAP) of 21–24 mmHg is above the upper limit of normal but does not reach criteria for the diagnosis of pulmonary hypertension (PH). We sought to determine whether an mPAP of 21–24 mmHg is associated with an increased risk of developing an abnormal pulmonary vascular response during exercise.Consecutive patients (n=290) with resting mPAP 30 mmHg and total pulmonary vascular resistance >3 WU at maximal exercise.Exercise PH occurred in 74 (86.0%) out of 86versus96 (47.1%) out of 204 in the mPAP of 21–24 mmHg and mPAP <21 mmHg groups, respectively (OR 6.9, 95% CI: 3.6–13.6; p<0.0001). Patients with mPAP of 21–24 mmHg had lower 6-min walk distance (p=0.002) and higher New York Heart Association functional class status (p=0.03). Decreasing levels of mPAP were associated with a lower prevalence of exercise PH, which occurred in 60.3%, 38.7% and 7.7% of patients with mPAP of 17–20, 13–16 and <13 mmHg, respectively.In an at-risk population, a resting mPAP between 21–24 mmHg is closely associated with exercise PH together with worse functional capacity.

Congenital portosystemic shunts are often associated with systemic complications, the most challenging of which are liver nodules, pulmonary hypertension, endocrine abnormalities, and neurocognitive dysfunction. In the present paper, we offer expert clinical guidance on the management of liver nodules, pulmonary hypertension, and endocrine abnormalities, and we make recommendations regarding shunt closure and follow-up.

We tested the hypothesis that vagal withdrawal plays a role in the rapid (phase I) cardiopulmonary response to exercise. To this aim, in five men (24.6 ± 3.4 yr, 82.1 ± 13.7 kg, maximal aerobic power 330 ± 67 W), we determined beat-by-beat cardiac output (Q̇), oxygen delivery (Q̇aO₂), and breath-by-breath lung oxygen uptake (V̇o₂) at light exercise (50 and 100 W) in normoxia and acute hypoxia (fraction of inspired O₂ = 0.11), because the latter reduces resting vagal activity. We computed Q̇ from stroke volume (Q_st, by model flow) and heart rate ( f_H, electrocardiography), and Q̇aO₂ from Q̇ and arterial O₂ concentration. Double exponentials were fitted to the data. In hypoxia compared with normoxia, steady-state f_H and Q̇ were higher, and Q_st and V̇o₂ were unchanged. Q̇aO₂ was unchanged at rest and lower at exercise. During transients, amplitude of phase I (A₁) for V̇o₂ was unchanged. For f_H, Q̇ and Q̇aO₂, A₁ was lower. Phase I time constant (τ₁) for Q̇aO₂ and V̇o₂ was unchanged. The same was the case for Q̇ at 100 W and for f_H at 50 W. Q_st kinetics were unaffected. In conclusion, the results do not fully support the hypothesis that vagal withdrawal determines phase I, because it was not completely suppressed. Although we can attribute the decrease in A₁ of f_H to a diminished degree of vagal withdrawal in hypoxia, this is not so for Q_st. Thus the dual origin of the phase I of Q̇ and Q̇aO₂, neural (vagal) and mechanical (venous return increase by muscle pump action), would rather be confirmed.