Iloprost als inhalative bzw. intravenöse Langzeitbehandlung von Patienten mit Primärer Pulmonaler Hypertonie – Register der Berliner Arbeitsgruppe für Pulmonale Hypertonie –

Intravenous prostacyclin-analogue therapy in pulmonary arterial hypertension - A review of the past, present and future

Therapy with intravenous prostacyclin analogues in patients with pulmonary arterial hypertension (PAH) has been established for decades and is an integral component of the current guidelines for the treatment of pulmonary hypertension. Initially, these drugs were infused by external pump systems via tunnelled right atrial catheters with the need for cooling and frequent exchange of drug reservoirs. Associated complications included, among others, catheter-related infections. More recently, fully implantable pump systems have been developed with drug reservoirs that are filled transcutaneously, allowing intervals between refills of several weeks. This technique results in a low rate of infections. Epoprostenol, iloprost and treprostinil have all been used intravenously in PAH, but titration, dosing and dose escalation in long-term therapy are not standardized. Intravenous prostacyclin analogues are still under-used, despite available data suggesting that early and broad application of these therapies as part of risk-oriented, guideline-directed combination therapy for patients with PAH may lead to a survival benefit. This review provides a detailed overview of the drugs, infusion systems and dosing strategies used for intravenous therapy in patients with PAH.

Icariin Attenuates Monocrotaline-Induced Pulmonary Arterial Hypertension via the Inhibition of TGF-β1/Smads Pathway in Rats

Background

Pulmonary artery remodeling is important in the development of pulmonary artery hypertension. The TGF-β1/Smads signaling pathway is activated in pulmonary arterial hypertension (PAH) in rats. Icariin (ICA) suppresses the TGF-β1/Smad2 pathway in myocardial fibrosis in rats. Therefore, we investigated the role of icariin in PAH by inhibiting the TGF-β1/Smads pathway.

Methods

Rats were randomly divided into control, monocrotaline (MCT), MCT + ICA-low, and MCT + ICA-high groups. MCT (60 mg/kg) was subcutaneously injected to induce PAH, and icariin (50 or 100 mg/kg.d) was orally administered for 2 weeks. At the end of the fourth week, right ventricular systolic pressure (RVSP) was obtained and the right ventricular hypertrophy index (RI) was determined as the ratio of the right ventricular weight to the left ventricular plus septal weight (RV/LV + S). Western blots were used to determine the expression of TGF-β1, Smad2/3, P-Smad2/3, and matrix metalloproteinase-2 (MMP2) in lung tissues.

Results

Compared to the control group, RVSP and RI were increased in the MCT group (ρ < 0.05). Additionally, TGF-β1, Smad2/3, P-Smad2/3, and MMP2 expressions were obviously increased (ρ < 0.01). Compared to the MCT group, RVSP and RI were decreased in the MCT + ICA group (ρ < 0.05). TGF-β1, Smad2/3, P-Smad2/3, and MMP2 expressions were also inhibited in the icariin treatment groups (ρ < 0.05). Conclusions. Icariin may suppress MCT-induced PAH via the inhibition of the TGFβ1-Smad2/3 pathway.

Severe pulmonary hypertension and right ventricular failure

Perioperative management of severe pulmonary hypertension (PH) is challenging. Anaesthesiologists come across perioperative management of such cases during incidental surgeries, surgery for various congenital heart diseases and valvular heart diseases and for caesarean section or painless labour in pregnant patient with Eisenmenger syndrome. Knowledge of pathophysiology of PH and novel drugs acting through different mechanisms is paramount in managing such patients. This review will help understanding pathophysiology of PH, anaesthetising patients with PH, use of novel drugs for PH and use of new mechanical devices for rescue of failing right ventricle.

Iloprost for idiopathic pulmonary arterial hypertension

Idiopathic pulmonary arterial hypertension is a rare but serious and life-threatening disease that leads to right heart failure and death within 2.8 years without specific treatment. This review focuses on the stable prostacyclin analog iloprost, its biologic action and pharmacology and, finally, on its clinical development, efficacy and safety in patients with idiopathic pulmonary arterial hypertension, which led to its approval for this indication. Furthermore, this review assesses the role of iloprost compared with other newly developed drugs, such as the endothelin receptor antagonist bosentan and the phosphodiesterase-5 inhibitor sildenafil, as well as other modes of application of prostacyclin and its analogs for the treatment of idiopathic pulmonary arterial hypertension. Based on the different modes of action of these substances, a combination of these treatments could be most promising for the future.

Inhaled low-dose iloprost for pulmonary hypertension: a prospective, multicenter, open-label study

BACKGROUND

Inhaled iloprost (average >30 µg/d) has been considered an effective treatment for severe pulmonary hypertension (PH). Further evidence also showed that low-dose iloprost given intravenously was equally effective as high-dose iloprost in the therapy of systemic sclerosis.

HYPOTHESIS

Patients with pulmonary hypertension will benefit from inhalation of low-dose iloprost.

METHODS

Sixty-two patients with PH were enrolled and initiated with neubulizedlow-dose iloprost (2.5 µg per inhalation, 6× daily) for 24 weeks in 13 medical centers in China. Efficacy endpoints included changes in 6-minute walk distance (6MWD), World Health Organization functional class (WHO-FC), and hemodynamic parameters.

RESULTS

Fourteen patients (22.6%) prematurely discontinued the study: 8 due to clinical worsening (6 in WHO-FCIII-IV at baseline), 4 because of protocol change, and 2 patients lost during follow-up. In the remaining 48 patients, 6MWD was increased from 356 ± 98 meters to 414 ± 99 meters (P < 0.001) and WHO-FC improved significantly (P = 0.006) after 24-week inhalation therapy. Cardiac output, cardiac index, and mixed venous oxygen saturation improved significantly compared with baseline (n = 34, P < 0.05). Most of the hemodynamic parameters improved significantly in patients in WHO-FC II (P < 0.05) but not in patients in WHO-FCIII-IV.

CONCLUSIONS

Low-dose iloprost inhalation significantly improved exercise capacity and functional status in patients with PH. It was well tolerated. The improvement of hemodynamics was confirmed in patients with WHO-FCI-II but not in patients with WHO-FCIII-IV, suggesting the importance of early treatment in patients with advanced disease stages.

Inhaled iloprost for therapy in pulmonary arterial hypertension

Iloprost (Ventavis, Bayer Schering Pharma, Germany) is a synthetic prostacyclin that is used in its inhalative form for the therapy of pulmonary arterial hypertension. Long-term therapy can increase exercise capacity and quality of life. The use of modern nebulizers especially designed for the administration of iloprost guarantees the pulmonary deposition of the required doses and systematically minimizes side effects. Regarding existing data, inhalative iloprost acts in effective and safe combination with other classes of medication; indeed, such combination therapy is frequently necessary in pulmonary arterial hypertension.

Inhaled iloprost for the control of pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by an elevated pulmonary arterial pressure and vascular resistance with a poor prognosis. Various pulmonary and extrapulmonary causes are now recognized to exist separately from the idiopathic form of pulmonary hypertension. An imbalance in the presence of vasoconstrictors and vasodilators plays an important role in the pathophysiology of the disease, one example being the lack of prostacyclin. Prostacyclin and its analogues are potent vasodilators with antithrombotic, antiproliferative and anti-inflammatory qualities, all of which are important factors in the pathogenesis of precapillary pulmonary hypertension. Iloprost is a stable prostacyclin analogue available for intravenous and aerosolized application. Due to the severe side effects of intravenous administration, the use of inhaled iloprost has become a mainstay in PAH therapy. However, owing to the necessity for 6 to 9 inhalations a day, oral treatment is often preferred as a first-line therapy. Numerous studies proving the efficacy and safety of inhaled iloprost have been performed. It is therefore available for a first-line therapy for PAH. The combination with endothelin-receptor antagonists or sildenafil has shown encouraging effects. Further studies with larger patient populations will have to demonstrate the use of combination therapy for long-term treatment of pulmonary hypertension.

Continuous intravenous iloprost to revert treatment failure of first-line inhaled iloprost therapy in patients with idiopathic pulmonary arterial hypertension

AIMS

To describe the clinical and haemodynamic effects during the first 6 months of continuous intravenous iloprost treatment in patients with idiopathic pulmonary arterial hypertension (IPAH) and relevant disease progression despite continued mono therapy with aerosolized iloprost.

METHODS AND RESULTS

Twenty-four IPAH patients with clinical decompensation to NYHA class IV despite therapy with aerosolized iloprost and optimized conservative treatment were assessed clinically, haemodynamically and by cardiopulmonary exercise testing for at least 6 months. Upon switching from inhaled to intravenous iloprost all patients improved clinically (NYHA III) while pulmonary vascular resistance (PVR) and right atrial pressure decreased from 2386 +/- 243 to 1381 +/- 124 dyne .s .cm(-5) and 12 +/- 1 to 8.5 +/- 1 mmHg, respectively (both p < 0.05). Despite this acute improvement haemodynamic (PVR increased from 1462+/-223 to 1978 +/- 327 dyne .s .cm(-5)) and clinical (4 deaths, 4 transplantations) deterioration occurred with continued intravenous treatment during the following 6 months.

CONCLUSIONS

In the group of patients described in this report the clinical and haemodynamic deterioration occurring while on mono therapy with inhaled iloprost could be stopped by switching to continuous application of intravenous iloprost. However, with continued intravenous therapy only a subgroup of patients could clinically be stabilized and transplanted successfully.

Advances in the Medical Treatment of Pulmonary Hypertension

Increased pulmonary precapillary vascular resistance due to vasoconstriction and vasoproliferative processes is the basic pathophysiological mechanism in the development of pulmonary hypertension (PH). With the exception of pulmonary venous hypertension, where the primary cause of PH is left ventricular failure or mitral valvular disease, all the other PH categories will benefit to a greater or lesser extent from pulmonary vasodilator and antivasoproliferative therapy. Today, for this purpose, in addition to intravenous prostacyclin (epoprostenol), which is restricted to severe pulmonary arterial hypertension (NYHA class IV and late class III), other therapeutic options such as treatment with more stable prostacyclin analogs (oral beraprost, aerosolized iloprost), endothelin-receptor antagonists (bosentan) or phosphodiesterase inhibitors (sildenafil) are also available and these are especially useful for the treatment of the early stages of the disease. The recent progress in medical therapy has markedly increased the life expectancy in patients with pulmonary arterial hypertension and substantially improved their quality of life. Chronic hemodialysis (HD) patients show higher endothelin-1 (ET-1) activity in comparison to healthy individuals and there is evidence that the increase of pulmonary vascular resistance in these patients is at least in part mediated by ET-1. Recent data show good results after PH therapy with the endothelin-receptor antagonist bosentan in HD patients. Also prostacyclin and its analogs, as well as phosphodiesterase inhibitors, can be useful for the treatment of pulmonary hypertension in patients with chronic renal failure.

Prostacyclin and its analogues in the treatment of pulmonary hypertension

Prostacyclin and its analogues (prostanoids) are potent vasodilators and possess antithrombotic and antiproliferative properties. All of these properties help to antagonize the pathological changes that take place in the small pulmonary arteries of patients with pulmonary hypertension. Indeed, several prostanoids have been shown to be efficacious to treat pulmonary hypertension, while the main mechanism underlying the beneficial effects remains unknown. There are indications of beneficial combination effects of prostaglandins and phosphodiesterase inhibitors and endothelin receptor antagonists. This speaks in favor of combination therapies for pulmonary hypertension in the future. The mode of application of prostanoids used in randomized controlled studies has been quite variable: continuous i.v. infusion of prostacyclin, continuous s.c. infusion of treprostinil, p.o. application of beraprost, and inhaled application of iloprost. In addition, the applied doses were quite different, ranging from 0.25 ng/kg/min for inhaled iloprost to 30-50 ng/kg/min for i.v. prostacyclin. While the principal pharmacological properties of all prostanoids are very similar due to a main action on IP receptors, there are considerable differences in pharmacokinetics and metabolism, with half-lives of 2 min for prostacyclin and about 34 min for treprostinil for i.v. infused drugs and half-lives of about 85 min for s.c. infused treprostinil. In addition, the adverse effects largely depend on the doses used and the mode of application, although there is great variability between subjects. It remains to be determined which patients will profit most from which substance (or combination) and mode of application.

Assessment of survival in patients with primary pulmonary hypertension: importance of cardiopulmonary exercise testing

BACKGROUND

Primary pulmonary hypertension (PPH) is a life-threatening disease. Prognostic assessment is an important factor in determining medical treatment and lung transplantation. Whether cardiopulmonary exercise testing data predict survival has not been reported previously.

METHODS AND RESULTS

We studied 86 patients with PPH (58 female, age 46+/-2 years, median NYHA class III) between 1996 and 2001 who were followed up in a tertiary referral center. Right heart catheterization was performed and serum uric acid levels were measured in all patients. Seventy patients were able to undergo exercise testing. At the start of the study, the average pulmonary artery pressure was 60+/-2 mm Hg, average pulmonary vascular resistance was 1664+/-81 dyne x s x cm(-5), average serum uric acid level was 7.5+/-0.35 mg/dL, and average peak oxygen uptake during exercise (peak VO(2) was 11.2+/-0.5 mL x kg(-1) x min(-1). During follow-up (mean: 567+/-48 days), 28 patients died and 16 underwent lung transplantation (1-year cumulative event-free survival: 68%; 95% CI 58 to 78). The strongest predictors of impaired survival were low peak VO(2) (P<0.0001) and low systolic blood pressure at peak exercise (peak SBP; P<0.0001). In a multivariable analysis, serum uric acid levels (all P<0.005) and diastolic blood pressure at peak exercise independently predicted survival (P<0.05). Patients with peak VO(2) < or =10.4 mL x kg(-1) x min(-1) and peak SBP < or =120 mm Hg (ie, 2 risk factors) had poor survival rates at 12 months (23%), whereas patients with 1 or none of these risk factors had better survival rates (79% and 97%, respectively).

CONCLUSIONS

Peak VO(2) and peak SBP are independent and strong predictors of survival in PPH patients. Hemodynamic parameters, although also accurate predictors, provide no independent prognostic information.

Peripheral airway obstruction in primary pulmonary hypertension

BACKGROUND

As there is controversy about changes in lung function in primary pulmonary hypertension (PPH), lung mechanics were assessed with a focus on expiratory airflow in relation to pulmonary haemodynamics.

METHODS

A cross sectional study was performed in 64 controls and 171 patients with PPH (117 women) of mean (SD) age 45 (13) years, pulmonary artery pressure (PAPmean) 57 (15) mm Hg, and pulmonary vascular resistance 1371 (644) dyne.s/cm(5).

RESULTS

Mean (SD) total lung capacity was similar in patients with PPH and controls (98 (12)% predicted v 102 (17)% predicted, mean difference -4 (95% confidence interval (CI) -7.89 to -0.11); residual volume (RV) was increased (118 (24)% predicted v 109 (27)% predicted, mean difference 9 (95% CI 1.86 to 16.14); and vital capacity (VC) was decreased (91 (16)% predicted v 102 (10)% predicted, mean difference -11 (95% CI 15.19 to -6.80). RV/TLC was increased (117 (27)% predicted v 97 (29)% predicted, mean difference 20 (95% CI 12.3 to 27.8)) and correlated with PAPmean (r=0.31, p<0.001). In patients with PAPmean above the median of 56 mm Hg, RV/TLC was further increased (125 (32)% predicted v 111 (22)% predicted, mean difference -14 (95% CI -22.2 to -5.8)). Expiratory flow-volume curves were reduced and curvilinear in patients with PPH.

CONCLUSIONS

Peripheral airway obstruction is common in PPH and is more pronounced in severe disease. This may contribute to symptoms. Reversibility of bronchodilation and relation to exercise capacity need further evaluation.