Pulmonary circulation and gas exchange at exercise in Sherpas at high altitude.

Tibetans have been reported to present with a unique phenotypic adaptation to high altitude characterized by higher resting ventilation and arterial oxygen saturation, no excessive polycythemia, and lower pulmonary arterial pressures (Ppa) compared with other high-altitude populations. How this affects exercise capacity is not exactly known. We measured aerobic exercise capacity during an incremental cardiopulmonary exercise test, lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) at rest, and mean Ppa (mPpa) and cardiac output by echocardiography at rest and at exercise in 13 Sherpas and in 13 acclimatized lowlander controls at the altitude of 5,050 m in Nepal.

Practical recommendations on the use of echocardiography to assess pulmonary arterial hypertension--a Belgian expert consensus endorsed by the Working Group on Non-Invasive Cardiac Imaging.

Pulmonary hypertension (PH) is defined by a sustained increase in mean pulmonary arterial pressure > 25 mmHg. Due to its widespread availability, echocardiography (ECHO) is used as the first-line imaging modality to detect pulmonary PH and assess right ventricular (RV) function in daily routine. As such, ECHO is the key examination to detect the presence of PH, to provide valuable prognostic information and to give an orientation to therapeutic strategies.

Right isovolumic contraction velocity predicts survival in pulmonary hypertension.

Background: Right ventricular function is a strong determinant of prognosis in severe pulmonary hypertension.

Methods: The aim of this study was to evaluate the prognostic value of estimates of right ventricular function obtained by echocardiography and Doppler tissue imaging and of functional class and 6-min walk distance (6MWD) in 142 patients with either pulmonary arterial hypertension (n = 104) or chronic thromboembolic pulmonary hypertension (n = 38). Echocardiography was prospectively performed, and demographics, medications, associated medical conditions, New York Heart Association class, and 6MWD at inclusion in addition to vital status, transplantation, and hospital admission related to pulmonary hypertension at follow-up were then collected by review of the medical records.

A critical review on telemonitoring in heart failure.

Morbidity and mortality remain high in heart failure despite considerable progress achieved with medical therapy and electrical devices. A multidisciplinary approach is actually strongly recommended. In order to provide optimal care to the ever-growing population of patients with heart failure, telemonitoring has been proposed as a modality to improve usual care.

Exercise testing to predict outcome in idiopathic versus associated pulmonary arterial hypertension.

We tested the ability of exercise testing to predict not only survival, but also time to clinical worsening (TTCW) in idiopathic versus associated pulmonary arterial hypertension (PAH). 136 patients with PAH (85 idiopathic and 51 with associated conditions) underwent cardiopulmonary exercise testing and a 6-min walk test. Death or transplantation, and clinical worsening events were recorded.

Safety, tolerability and pharmacokinetics of an intravenous bolus of sildenafil in patients with pulmonary arterial hypertension.

Aims: To assess pharmacokinetics and pharmacodynamics of a 10 mg intravenous sildenafil bolus in pulmonary arterial hypertension (PAH) patients stabilized on 20 mg sildenafil orally three times daily.

Methods: Pharmacokinetic parameters were calculated using noncompartmental analysis.

Results: After an acute increase, plasma concentrations stabilized within the range reported previously for a 20 mg oral tablet.

Pulmonary capillary blood volume and membrane conductance in Andeans and lowlanders at high altitude: a cross-sectional study.

Lung carbon monoxide (CO) transfer and pulmonary capillary blood volume (Vc) at high altitudes have been reported as being higher in native highlanders compared to acclimatised lowlanders but large discrepancies appears between the studies. This finding raises the question of whether hypoxia induces pulmonary angiogenesis. Eighteen highlanders living in Bolivia and 16 European lowlander volunteers were studied.

Echocardiographic and tissue Doppler imaging of cardiac adaptation to high altitude in native highlanders versus acclimatized lowlanders.

High-altitude exposure is a cause of pulmonary hypertension and decreased exercise capacity, but associated changes in cardiac function remain incompletely understood. The aim of this study was to investigate right ventricular (RV) and left ventricular function in acclimatized Caucasian lowlanders compared with native Bolivian highlanders at high altitudes. Standard echocardiography and tissue Doppler imaging studies were performed in 15 healthy lowlanders at sea level; <24 hours after arrival in La Paz, Bolivia, at 3,750 m; and after 10 days of acclimatization and ascent to Huayna Potosi, at 4,850 m, and the results were compared with those obtained in 15 age- and body size-matched inhabitants of Oruro, Bolivia, at 4,000 m.

Stress Doppler echocardiography in relatives of patients with idiopathic and familial pulmonary arterial hypertension: results of a multicenter European analysis of pulmonary artery pressure response to exercise and hypoxia.

Background: This large, prospective, multicentric study was performed to analyze the distribution of tricuspid regurgitation velocity (TRV) values during exercise and hypoxia in relatives of patients with idiopathic and familial pulmonary arterial hypertension (PAH) and in healthy control subjects. We tested the hypothesis that relatives of idiopathic/familial PAH patients display an enhanced frequency of hypertensive TRV response to stress and that this response is associated with mutations in the bone morphogenetic protein receptor II (BMPR2) gene.

Methods And Results: TRV was estimated by Doppler echocardiography during supine bicycle exercise in normoxia and during 120 minutes of normobaric hypoxia (FIO(2)=12%; approximately 4500 m) in 291 relatives of 109 PAH patients and in 191 age-matched control subjects.

Improvement in right ventricular function during reversibility testing in pulmonary arterial hypertension: a case report.

A right heart catheterization with reversibility testing is recommended for the diagnosis and treatment of pulmonary arterial hypertension. In this 24 years-old woman, the inhalation of 5 microg iloprost transiently decreased mean pulmonary artery pressure from 62 to 36 mmHg and pulmonary vascular resistance from 11.0 to 4.

Bosentan decreases pulmonary vascular resistance and improves exercise capacity in acute hypoxia.

Background: Altitude exposure is associated with mild pulmonary hypertension and decreased exercise capacity. We tested the hypothesis that pulmonary vascular resistance (PVR) contributes to decreased exercise capacity in hypoxic healthy subjects.

Methods: An incremental cycle ergometer cardiopulmonary exercise test and echocardiographic estimation of pulmonary artery pressure (Ppa) and cardiac output to calculate total PVR were performed in 11 healthy volunteers in normoxia and after 1 h of hypoxic breathing (12% O(2)).

Tissue Doppler imaging evaluation of cardiac adaptation to severe pulmonary hypertension.

Tissue Doppler imaging (TDI) was used to obtain additional insight into the cardiac adaptation to severe pulmonary arterial hypertension. Pulmonary hemodynamics and right and left ventricular function were investigated in 18 untreated patients, 12 with pulmonary arterial hypertension and 6 with chronic thromboembolic pulmonary hypertension. Fourteen age-matched healthy subjects served as controls for TDI measurements.

Expert opinion on available options treating pulmonary arterial hypertension.

Until in the early nineties, pulmonary arterial hypertension (PAH) was a uniformly fatal disease, with a median life expectancy of approximately 2.5 years. Uncontrolled studies showed that a small proportion of patients responded to high-dose calcium channel blockers, retrospective studies supported the use of anticoagulant therapy and heart-lung or lung transplantation remained the only option.

Effects of acetazolamide on aerobic exercise capacity and pulmonary hemodynamics at high altitudes.

Aerobic exercise capacity is decreased at altitude because of combined decreases in arterial oxygenation and in cardiac output. Hypoxic pulmonary vasoconstriction could limit cardiac output in hypoxia. We tested the hypothesis that acetazolamide could improve exercise capacity at altitude by an increased arterial oxygenation and an inhibition of hypoxic pulmonary vasoconstriction.

Effects of sildenafil on exercise capacity in hypoxic normal subjects.

The phosphodiesterase-5 inhibitor sildenafil has been reported to improve hypoxic exercise capacity, but the mechanisms accounting for this observation remain incompletely understood. Sixteen healthy subjects were included in a randomized, double-blind, placebo-controlled, cross-over study on the effects of 50-mg sildenafil on echocardiographic indexes of the pulmonary circulation and on cardiopulmonary cycle exercise in normoxia, in acute normobaric hypoxia (fraction of inspired O2, 0.1), and then again after 2 weeks of acclimatization at 5000 m on Mount Chimborazo (Ecuador).

Sitaxsentan for the prevention of experimental shunt-induced pulmonary hypertension.

We previously reported on the partial prevention of experimental shunt-induced pulmonary arterial hypertension (PAH) by the nonselective endothelin (ET) ET-A/ET-B receptor antagonist bosentan. As the respective roles of the ET-A and ET-B receptor signaling in the pathobiology of the disease remain undefined, we investigated the effects of selective ET-A receptor blockade by sitaxsentan in the same early stage PAH model. Twenty-one 3-wk-old piglets were randomized to placebo or sitaxsentan therapy (1.

Effects of levosimendan versus dobutamine on pressure load-induced right ventricular failure.

Objective: A transient increase in pulmonary arterial (PA) pressure can persistently depress right ventricular (RV) contractility. We investigated the effects of dobutamine and levosimendan on RV-PA coupling in this model of RV failure.

Design: Prospective, controlled, randomized animal study.

Prevention of pulmonary vascular remodeling and of decreased BMPR-2 expression by losartan therapy in shunt-induced pulmonary hypertension.

The renin-ANG system has been reported to be overexpressed in pulmonary arterial hypertension (PAH). We investigated the effects of ANG receptor-1 blockade by losartan on hemodynamics and signaling molecules in a piglet overflow model of early PAH. Twenty-six 3-wk-old piglets were randomized to placebo or losartan therapy (1 mg.

Right and left ventricular adaptation to hypoxia: a tissue Doppler imaging study.

Hypoxia has been reported to alter left ventricular (LV) diastolic function, but associated changes in right ventricular (RV) systolic and diastolic function remain incompletely documented. We used echocardiography and tissue Doppler imaging to investigate the effects on RV and LV function of 90 min of hypoxic breathing (fraction of inspired O(2) of 0.12) compared with those of dobutamine to reproduce the same heart rate effects without change in pulmonary vascular tone in 25 healthy volunteers.

Feasibility of routine pulmonary arterial impedance measurements in pulmonary hypertension.

Objectives: Right ventricular (RV) afterload is best described by a pulmonary arterial impedance (PVZ) spectrum, which integrates pulmonary vascular resistance (PVR), elastance, and wave reflection. We evaluated the feasibility of PVZ determinations in patients with pulmonary arterial hypertension (PAH) during routine right heart catheterization and Doppler echocardiography.

Design: Prospective study.