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. In Sherpas vs. lowlanders, arterial oxygen saturation was 86 ± 1 vs. 83 ± 2% (mean ± SE; P = nonsignificant), mPpa at rest 19 ± 1 vs. 23 ± 1 mmHg (P < 0.05), DL(CO) corrected for hemoglobin 61 ± 4 vs. 37 ± 2 ml · min(-1) · mmHg(-1) (P < 0.001), DL(NO) 226 ± 18 vs. 153 ± 9 ml · min(-1) · mmHg(-1) (P < 0.001), maximum oxygen uptake 32 ± 3 vs. 28 ± 1 ml · kg(-1) · min(-1) (P = nonsignificant), and ventilatory equivalent for carbon dioxide at anaerobic threshold 40 ± 2 vs. 48 ± 2 (P < 0.001). Maximum oxygen uptake was correlated directly to DL(CO) and inversely to the slope of mPpa-cardiac index relationships in both Sherpas and acclimatized lowlanders. We conclude that Sherpas compared with acclimatized lowlanders have an unremarkable aerobic exercise capacity, but with less pronounced pulmonary hypertension, lower ventilatory responses, and higher lung diffusing capacity.

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. In addition to detection and screening, ECHO also provides clues for the differential diagnosis of PH. The present document, based on a consensus of experts, provides practical recommendations for the use of ECHO in the evaluation of PH and of its consequences on the right ventricle.

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. RESULTS: Variables associated with overall survival by univariate analysis were 6MWD (P = .009), functional class (P = .024), tricuspid annular plane systolic excursion (P = .03) and isovolumic peak velocity at the tricuspid annulus (IVCv) (P = .003). On multivariate analysis, IVCv (P = .015) and 6MWD (P = .016) were the only independent predictors of survival. Kaplan-Meier estimates of survival at 1 year were 95% in patients with IVCv > 9 cm/sec and 80% in those with IVCv ≤ 9 cm/sec (P = .002). Intraobserver and interobserver variability of IVCv measurement were 5% and 9%, respectively. CONCLUSIONS: Measurement of right ventricular function by Doppler tissue imaging, an easy, noninvasive, and reproducible method, is an independent predictor of clinical outcomes in patients with severe pulmonary hypertension.

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. The aim of this review is to provide an overview of the existing evidence on telemonitoring in HF. Despite two major meta-analyses with favourable results, two recent, large, multicentre, randomized controlled trials, one with a sophisticated technical remote telemonitoring approach (TIM-HF) in stable chronic HF and the other with a comprehensive telephone-based interactive voice-response monitoring (Tele-HF) in patients recently hospitalized for heart failure, have been performed and both failed to demonstrate a clinical benefit for telemonitoring. Newer technologies or other modalities, such as collaboration between a general practitioner and a heart failure clinic facilitated by telemonitoring should be further evaluated. Dedicated telemonitoring for heart failure may be a practical adjunct in selective centres and patients, on top of usual care, including education and a multidisciplinary approach. However, prior to being accepted as a standard of care, more evidence from large, randomized clinical trials is required.

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. 32 patients died and four had lung transplantation. In a univariate analysis, PAH patients survival was associated with oxygen uptake (V'(O(2))) at peak exercise and at the anaerobic threshold, ventilatory equivalent for carbon dioxide (minute ventilation (V'(E))/carbon dioxide production (V'(CO(2))) at the anaerobic threshold ((at))), V'(E)/V'(CO(2)) slope and distance walked. TTCW was associated with peak V'(O(2)) and V'(O(2),at), V'(E)/V'(CO(2),at), end-tidal carbon dioxide tension measured at the anaerobic threshold, peak oxygen pulse, increase in oxygen pulse and distance walked. In a multivariable analysis, distance walked and V'(E)/V'(CO(2),at) predicted survival, and only peak V'(O(2)) predicted TTCW. The receiver operating characteristic curve-derived cut-off values were 305 m for the 6-min walk distance, 54 for V'(E)/V'(CO(2),at) and 11.6 mL·kg(-1)·min for peak V'(O(2)). In the subgroup with associated PAH, no variable independently predicted either survival or clinical worsening. We conclude that several exercise variables predict survival and clinical stability in idiopathic PAH. Exercise variables are less accurate predictors of outcome in associated PAH.

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. At 0.5 h, mean ± SD changes from baseline were -8.4 ± 11.7 mmHg (systolic pressure), -2.6 ± 7.3 mmHg (diastolic pressure) and -3.5 ± 10.4 beats min(-1) (heart rate). There was no symptomatic hypotension. CONCLUSIONS: Although further research is warranted, a 10 mg sildenafil intravenous bolus appears to provide similar exposure, tolerability and safety to the 20 mg 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. The latter were studied both at sea level and after acclimatisation to high altitude. Membrane conductance (Dm(CO)) and Vc, corrected for the haemoglobin concentration (Vc(cor)), were calculated using the NO/CO transfer technique. Pulmonary arterial pressure and left atrial pressures were estimated using echocardiography. Highlanders exhibited significantly higher NO and CO transfer than acclimatised lowlanders, with Vc(cor)/VA and Dm(CO)/VA being 49 and 17% greater (VA: alveolar volume) in highlanders, respectively. In acclimatised lowlanders, Dm(CO) and Dm(CO)/VA values were lower at high altitudes than at sea level. Echocardiographic estimates of cardiac output and pulmonary arterial pressure were significantly elevated at high altitudes as compared to sea level. The decrease in Dm(CO) in lowlanders might be due to altered gas transport in the airways due to the low density of air at high altitudes. The disproportionate increase in Vc in Andeans compared to the change in Dm(CO) suggests that the recruitment of capillaries is associated with a thickening of the blood capillary sheet. Since there was no correlation between the increase in Vc and the slight alterations in haemodynamics, this data suggests that chronic hypoxia might stimulate pulmonary angiogenesis in Andeans who live at high altitudes.

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. Acute exposure to high altitude in lowlanders caused an increase in mean pulmonary arterial pressure, to 20 to 25 mm Hg, and altered RV and left ventricular diastolic function, with prolonged isovolumic relaxation time, an increased RV Tei index, and maintained RV systolic function as estimated by tricuspid annular plane excursion and the tricuspid annular S wave. This profile was essentially unchanged after acclimatization and ascent to 4,850 m, except for higher pulmonary arterial pressure. The native highlanders presented with relatively lower pulmonary arterial pressures but more pronounced alterations in diastolic function, decreased tricuspid annular plane excursion and tricuspid annular S waves, and increased RV Tei indexes. In conclusion, cardiac adaptation to high altitude was qualitatively similar in acclimatized Caucasian lowlanders and in Bolivian native highlanders. However, lifelong exposure to high altitude may be associated with different cardiac adaptation to milder hypoxic pulmonary hypertension.

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. Mean maximal TRVs were significantly higher in PAH relatives during both exercise and hypoxia. During exercise, 10% of control subjects but 31.6% of relatives (P<0.0001) exceeded the 90% quantile of mean maximal TRV seen in control subjects. Hypoxia revealed hypertensive TRV in 26% of relatives (P=0.0029). Among control subjects, TRV at rest was not related to age, sex, body mass index, systemic blood pressure, smoking status, or heart rate. Within kindreds identified as harboring deleterious mutations of the BMPR2 gene, a hypertensive TRV response occurred significantly more often compared with those without detected mutations. CONCLUSIONS: Pulmonary hypertensive response to exercise and hypoxia in idiopathic/familial PAH relatives appears as a genetic trait with familial clustering, being correlated to but not caused by a BMPR2 mutation. The suitability of this trait to predict manifest PAH development should be addressed in long-term follow-up studies.

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 4.9 Wood units, meeting the criteria of a "positive response". The echocardiographic examination showed normalization of right heart chamber dimensions and of the right ventricular performance (Tei) index. Pulsed tissue Doppler imaging of the right ventricle showed a decrease in the isovolumic relaxation time from 102 to 73 ms, and an increase of the E/A ratio from 0.72 to 1.38, together with marked improvements in mid-apical free wall systolic strain and strain rate. A positive response to reversibility testing of pulmonary arterial hypertension may be associated with quasi normalization of right ventricular function, in spite of still elevated pulmonary artery pressure.

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)). The measurements were performed in a random order at 1-week intervals after the receiving either a placebo or bosentan, following a double-blind randomized crossover design. Bosentan was administered twice a day for 3 days, 62.5 mg on the first day and 125 mg on the next 2 days. RESULTS: Hypoxic breathing decreased the mean (+/- SE) pulse oximetric saturation (Spo(2)) from 99 +/- 1% to 3 +/- 1% and increased the mean PVR from 5.6 +/- 0.3 to 7.2 +/- 0.5 mm Hg/L/min/m(2), together with a decrease in mean maximum O(2) uptake (Vo(2)max) from 47 +/- 2 to 35 +/- 2 mL/kg/min. Bosentan had no effect on normoxic measurements and did not affect hypoxic Spo(2), but decreased PVR to 5.6 +/- 0.3 mm Hg/L/min/m(2) (p < 0.01) and increased Vo(2)max to 39 +/- 2 mL/kg/min (p < 0.01) in hypoxia. Bosentan therapy, on average, restored 30% of the hypoxia-induced decrease in Vo(2)max. Bosentan-induced changes in Ppa and Vo(2)max were correlated (p = 0.01). CONCLUSIONS: We conclude that hypoxic pulmonary hypertension partially limits exercise capacity in healthy subjects, and that bosentan therapy can prevent it.

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. In 1996, a 3-month randomised, placebo-controlled trial showed that chronic intravenous epoprostenol (synthetic prostacyclin) improved functional state, exercise capacity, haemodynamics, and even survival in patients with idiopathic PAH. Similar benefits were subsequently reported and extended to all PAH categories, and confirmed with more stable prostacyclin analogues administered subcutaneously (treprostinil), by inhalation (iloprost), or even orally (beraprost). In the early 2000s, two randomised controlled trials showed efficacy of the oral intake of the dual endothelin A/B receptor antagonist bosentan. Two selective endothelin-A receptor antagonists, sitaxsentan and ambrisentan, are being developed. Finally, a randomised controlled trial has established the therapeutic efficacy of phosphodiesterase-5 inhibition with sildenafil, introducing a third signalling pathway to be targeted by the pharmacological treatment of PAH. Another phosphodiesterase-5 inhibitor, tadalafil, is already being evaluated. While all these treatments have markedly improved the lives of PAH patients, they have not offered yet a cure of the disease. Multi-drug approaches are now under evaluation, with more ambitious therapeutic goals. Alternative approaches with stem cells, RhoA-Rho-kinase inhibitors, platelet derived growth factor inhibitors and vasoactive intestinal peptides are being considered.

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. Pulsed TDI was determined using atrioventricular planes and strain and strain rate along the right ventricular free wall, ventricular septum, and left ventricular lateral wall from 4-chamber apical views. Patients had early diastolic dysfunction, with decreased E-wave peak velocity and increased isovolumic relaxation time, both more important in the right than left ventricle. Compared with controls, strain and strain rate decreased along the right ventricular free wall with a midapical predominance (midbasal strain rate 1.7 +/- 0.6 vs 2.2 +/- 0.5; p = 0.02; midapical strain rate 0.9 +/- 0.9 vs 2.3 +/- 0.7; p <0.001), but were preserved along the left ventricular lateral wall. Tricuspid E-wave and isovolumic relaxation time (R = 0.62, p = 0.006), as well as midapical (r = 0.65, p = 0.004), but not midbasal, right ventricular strain and strain rate correlated with mean pulmonary artery pressures. In conclusion, cardiac function was abnormal in patients with severe pulmonary hypertension because of a combination of alterations in both diastolic and systolic right ventricular function and left ventricular diastolic function. Only right ventricular dysfunction correlated with pulmonary artery pressures.

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. Resting and exercise pulmonary artery pressure (Ppa) and flow (Q) (Doppler echocardiography) and exercise capacity (cardiopulmonary exercise test) were determined at sea level, 10 days after arrival on the Bolivian altiplano, at Huayna Potosi (4,700 m), and again after the intake of 250 mg acetazolamide vs. a placebo three times a day for 24 h. Acetazolamide and placebo were administered double-blind and in a random sequence. Altitude shifted Ppa/Q plots to higher pressures and decreased maximum O(2) consumption ((.)Vo(2max)). Acetazolamide had no effect on Ppa/Q plots but increased arterial O(2) saturation at rest from 84 +/- 5 to 90 +/- 3% (P < 0.05) and at exercise from 79 +/- 6 to 83 +/- 4% (P < 0.05), and O(2) consumption at the anaerobic threshold (V-slope method) from 21 +/- 5 to 25 +/- 5 ml.min(-1).kg(-1) (P < 0.01). However, acetazolamide did not affect (.)Vo(2max) (from 31 +/- 6 to 29 +/- 7 ml.kg(-1).min(-1)), and the maximum respiratory exchange ratio decreased from 1.2 +/- 0.06 to 1.05 +/- 0.03 (P < 0.001). We conclude that acetazolamide does not affect maximum exercise capacity or pulmonary hemodynamics at high altitudes. Associated changes in the respiratory exchange ratio may be due to altered CO(2) production kinetics.

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). In normoxia, sildenafil had no effect on maximum VO2 or O2 saturation. In acute hypoxia, sildenafil increased maximum VO2 from 27 +/- 5 to 32 +/- 6 mL/min/kg and O2 saturation from 62% +/- 6% to 68% +/- 9%. In chronic hypoxia, sildenafil did not affect maximum VO2 or O2 saturation. Resting mean pulmonary artery pressure increased from 16 +/- 3 mmHg in normoxia to 28 +/- 5 mmHg in normobaric hypoxia and 32 +/- 6 mmHg in hypobaric hypoxia. Sildenafil decreased pulmonary vascular resistance by 30% to 50% in these different conditions. We conclude that sildenafil increases exercise capacity in acute normobaric hypoxia and that this is explained by improved arterial oxygenation, rather than by a decrease in right ventricular afterload.

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 (1.5 mg/kg/d), after anastomosis of the left subclavian artery to the pulmonary arterial trunk or after a sham operation. Three months later, the animals underwent a hemodynamic evaluation, followed by pulmonary tissue sampling for morphometry and real-time-quantitative-PCR for ET-1, angiopoietin-1, and bone morphogenetic receptor (BMPR) signaling molecules. Three months of left to right shunting induced an increase in pulmonary vascular resistance (PVR) and medial thickness, an overexpression of ET-1, ET-B receptor, and angiopoietin-1, and a decreased expression of BMPR-2 and BMPR-1A. Pretreatment with sitaxsentan prevented shunt-induced increase in PVR and decreased medial thickness by 64%. Sitaxsentan therapy completely prevented the decreased expression of BMPR-2 and limited the overexpression of ET-1, ET-B and angiopoietin-1, and the decreased expression of BMPR-1A. In conclusion, selective ET-A receptor blockade partially prevents shunt-induced PAH.

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. SETTING: University research laboratory. SUBJECTS: Fifteen anesthetized dogs. INTERVENTIONS: Transient (90-min) PA constriction to induce persistent RV failure. Random assignment to dobutamine 5 and 10 microg/kg/min or levosimendan 12 microg/kg for 10 mins followed by 0.1 and 0.2 microg/kg/min. MEASUREMENTS AND MAIN RESULTS: We measured PA distal resistance and proximal elastance by pressure-flow relationships and vascular impedance. We measured RV contractility by the end-systolic pressure-volume relationship (Ees), PA effective elastance by the end-diastolic to end-systolic relationship (Ea), and RV-PA coupling efficiency by the Ees/Ea ratio. PA constriction persistently increased PA resistance and elastance, increased Ea from 0.95 +/- 0.07 to 3.01 +/- 0.28 mm Hg/mL, decreased Ees from 1.17 +/- 0.09 to 0.58 +/- 0.07 mm Hg/mL, and decreased Ees/Ea from 1.26 +/- 0.09 to 0.22 +/- 0.03 (p < .05). Dobutamine did not affect pulmonary hemodynamics, markedly increased RV contractility, and improved RV-PA coupling. Levosimendan decreased PA resistance and elastance, increased RV contractility, and restored RV-PA coupling. Compared with dobutamine, levosimendan decreased RV afterload and therefore better restored RV-PA coupling at similar inotropic state. CONCLUSIONS: A transient increase in PA pressure persistently worsens PA hemodynamics, RV contractility, RV-PA coupling, and cardiac output. Levosimendan restores RV-PA coupling better than dobutamine because of similar inotropic effects and additional pulmonary vasodilatory effects.

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.kg(-1).day(-1)) after anastomosis of the inominate to the main pulmonary artery or after a sham operation. Three months later, the animals underwent a hemodynamic evaluation, followed by pulmonary tissue sampling for morphometry, immunohistochemistry, and real-time quantitative-PCR. Chronic systemic-to-pulmonary shunting increased the pulmonary vascular resistance from 2.5 +/- 0.2 to 6.2 +/- 0.3 mmHg.l(-1).min.m(-2) and arteriolar medial thickness from 13.6 to 25.4%. These changes were associated with increased expressions of ANG II and its type 1 (AT1) and type 2 (AT2) receptors, endothelin-1 (ET-1) and its type B receptor (ETB), and angiopoietin-1, together with decreased expressions of bone morphogeneic protein receptor-1A and -2 (BMPR-1A and BMPR-2, respectively) and unchanged expression of the receptor tyrosine kinase with immunoglobulin and EGF homology domains-2 (Tie 2). Pretreatment with losartan decreased shunt-induced pulmonary vascular resistance and medial thickness by 51% and 35%, respectively. Losartan therapy was associated with persistent overexpressions of ANG II, AT2, ET-1, ETB, and angiopoietin-1 and with a return to normal of the BMPR-2 expression. These results suggest that ANG II contributes to left-to-right, shunt-induced PAH.