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Background: Pulmonary arterial hypertension (PAH) is associated with increased right ventricular (RV) afterload, RV dysfunction and decreased peak oxygen uptake (pVO 2 ). However, the pulmonary hemodynamic mechanisms measured by exercise right heart catheterization (RHC) that contribute to reduced pVO 2 in idiopathic PAH (IPAH) are not completely characterized. Therefore, we sought to evaluate the exercise RHC determinants of pVO 2 in patients with IPAH., Methods: 519 consecutive patients with suspected and/or confirmed pulmonary hypertension were prospectively screened to identify 20 patients with IPAH. All IPAH patients were prospectively evaluated with resting and exercise RHC and cardiopulmonary exercise testing., Results: 85% of the patients were female; the median age was 34[29-42] years old. At peak exercise, mean pulmonary arterial (PA) pressure was 76 ± 17 mmHg, PA wedge pressure was 14 ± 5 mmHg, cardiac output (CO) was 5.7 ± 1.9 L/min, pulmonary vascular resistance was 959 ± 401 dynes/s/cm 5 and PA compliance was 0.9[0.6-1.2] ml/mmHg. On univariate analysis, pVO2 positively correlated to peak CO, peak cardiac index, peak stroke volume index, peak RV stroke work index (RVSWI) and peak oxygen saturation. There was a negative correlation between pVO 2 and Δ (rest to peak change) PA compliance. In age-adjusted multivariate model, peak RVSWI (Coefficient = 0.15, Beta = 0.63, 95% CI [0.07-0.22], p < 0.01) and ΔPA compliance (Coefficient = -2.51, Beta = -0.43, 95% CI [-4.34-(-0.68)], p = 0.01) had the best performance predicting pVO 2 (R 2  = 0.66)., Conclusions: In conclusion, a load dependent measurement of RV function (RVSWI) and the pulsatile component of RV afterload (ΔPA compliance) significantly influence pVO 2 in IPAH, further highlighting the pivotal role of hemodynamic coupling to IPAH exercise capacity., Competing Interests: Declaration of Competing Interest None., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Hypocapnia and endothelial dysfunction might impair microvascular cerebral blood flow (CBF micr ) and cerebrovascular reactivity to CO 2 (CVR CO2 ). Pulmonary arterial hypertension (PAH) is characteristically associated with chronic alveolar hyperventilation and microvascular endothelial dysfunction. We therefore determined CBF micr (pre-frontal blood flow index (BFI) by the indocyanine green-near infrared spectroscopy methodology) during hypocapnia and hypercapnia in 25 PAH patients and 10 gender- and age-matched controls. Cerebral BFI was lower in patients than controls at similar transcutaneous PCO 2 (PtcCO 2 ) levels in both testing conditions. In fact, while BFI increased from hypocapnia to hypercapnia in all controls, it failed to increase in 17/25 (68%) patients. Thus, BFI increased to a lesser extent from hypo to hypercapnia ("Δ") in patients, i.e., they showed lower Δ BFI/Δ PtcCO 2 ratios than controls. In conclusion, CBF micr and CVR CO2 are lessened in clinically stable, mildly-impaired patients with PAH. These abnormalities might be associated with relevant clinical outcomes (hyperventilation and dyspnea, cognition, cerebrovascular disease) being potentially amenable to pharmacological treatment., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Increased ventilatory (.VE) response to carbon dioxide output (.VCO2) is a key finding of incremental cardiopulmonary exercise testing in both heart failure and pulmonary arterial hypertension (PAH). As with heart failure, measures of excessive exercise ventilation considering high-to-peak exercise .VE-VCO2 might have higher prognostic relevance than those restrained to sub-maximal exercise in PAH., Design: Cross-sectional and observational study on a tertiary center., Methods: Eighty-four patients (36 idiopathic and 48 with associated conditions) were followed up for up to five years. Excessive exercise ventilation was calculated as a slope (Δ .VE/Δ .VCO2 to the respiratory compensation point (RCP) and to exercise cessation (PEAK)) and as a ratio (.VE-VCO2 at the anaerobic threshold (AT) and at PEAK)., Results: Thirteen patients died and three had atrial septostomy. Multivariable regression analyses revealed that Δ .VE/Δ .VCO2(PEAK) <55 and .VE/.VCO2(PEAK) <57 were better related to prognosis than Δ .VE/Δ .VCO2(RCP) and .VE/.VCO2(AT) (p < 0.01). Δ oxygen uptake (.VO2)/Δ work rate >5.5 ml/min per W was the only other independent prognostic index. According to a Kaplan-Meier survival analysis, 96.9% (90.8% to 100%) of patients showing Δ .VE/Δ .VCO2(PEAK) <55 and Δ .VO2/Δ work rate >5.5 ml/min per W were free from a PAH-related event. In contrast, 74.7% (70.1% to 78.2%) with both parameters outside these ranges had a negative outcome., Conclusion: Measurements of excessive exercise ventilation which consider all data points maximize the usefulness of incremental cardiopulmonary exercise testing in the prognosis evaluation of PAH., (© The European Society of Cardiology 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

Background: Pulmonary arterial hypertension (PAH) is characterized by a pulmonary capillary wedge pressure (PCWP) of ≤15 mm Hg, given a normal left ventricular filling pressure (LVFP). However, recent studies have shown that, in PAH patients, diagnosis based on PCWP can erroneously classify a significant number of patients compared with diagnosis based on left ventricular end-diastolic pressure (LVEDP). Therefore, we sought to compare the diagnostic accuracy of end-expiratory PCWP and LVEDP measurements in patients suspected of having pulmonary hypertension (PH)., Methods: We reviewed the hemodynamic data from 122 patients suspected of having PH who underwent simultaneous right- and left-side heart catheterizations at a PH referral center from 2006 to 2011., Results: PH was diagnosed in 105 patients, 79% of whom (n = 83) showed a pre-capillary pattern according to the LVEDP measurement. Ninety percent of patients with PCWP ≤15 mm Hg were correctly classified as having pre-capillary PH. However, 39% of patients with a PCWP >15 mm Hg had LVEDP ≤15 mm Hg and would have been erroneously diagnosed with pulmonary venous hypertension based on their PCWP measurements alone. The sensitivity and specificity was 0.89 and 0.64, respectively. A Bland-Altman analysis of the PCWP and LVEDP measurements revealed a mean bias of 0.3 mm Hg with 95% limits of agreement of -7.2 to 7.8 mm Hg., Conclusions: A PCWP ≤15 mm Hg was found to be a reliable indicator of normal LVFP in pre-capillary PH patients. When measured properly and analyzed in the clinical context, PCWP is a valuable tool for accurate diagnosis of PAH., (© 2014 International Society for Heart and Lung Transplantation Published by International Society for the Heart and Lung Transplantation All rights reserved.)

Background: Delayed postexercise heart rate recovery (HRR) has been associated with disability and poor prognosis in chronic cardiopulmonary diseases. The usefulness of HRR to predict exercise impairment and mortality in patients with pulmonary arterial hypertension (PAH), however, remains largely unexplored., Methods: Seventy-two patients with PAH of varied etiology (New York Heart Association classes I-IV) and 21 age- and gender-matched controls underwent a maximal incremental cardiopulmonary exercise test (CPET), with heart rate being recorded up to the fifth minute of recovery., Results: Heart rate recovery was consistently lower in the patients compared with the controls (P < .05). The best cutoff for HRR in 1 minute (HRR(1 min)) to discriminate the patients from the controls was 18 beats. Compared with patients with HRR(1 min) ≤ 18 (n = 40), those with HRR(1 min) >18 (n = 32) had better New York Heart Association scores, resting hemodynamics and 6-minute walking distance. In fact, HRR(1 min) >18 was associated with a range of maximal and submaximal CPET variables indicative of less severe exercise impairment (P < .05). The single independent predictor of HRR(1 min) ≤ 18 was the 6-minute walking distance (odds ratio [95% CI] 0.99 [0.98-1.00], P < .05). On a multiple regression analysis that considered only CPET-independent variables, HRR(1 min) ≤ 18 was the single predictor of mortality (hazard ratio [95% CI] 1.19 [1.03-1.37], P < .05)., Conclusions: Preserved HRR(1 min) (>18 beats) is associated with less impaired responses to incremental exercise in patients with PAH. Conversely, a delayed HRR(1 min) response has negative prognostic implications, a finding likely to be clinically useful when more sophisticated (and costlier) analyses provided by a full CPET are not available., (Copyright © 2012 Mosby, Inc. All rights reserved.)