Inhaled prostacyclin and iloprost in severe pulmonary hypertension secondary to lung fibrosis

Pulmonary hypertension: current diagnosis and treatment

Pulmonary hypertension (PH) is a devastating disease that - if untreated - is characterized by a poor prognosis. According to the current classification (Venice, 2003), pulmonary arterial hypertension (PAH) is distinguished from other forms of PH. Recent advances in drug therapy have led to a dramatic improvement of medical care particularly in patients with PAH. Hence, early establishment of the diagnosis appears increasingly important. This review article gives an overview on the definition, classification, pathophysiology, and clinical presentation of various forms of PH. Furthermore, it summarizes the recommended diagnostic work-up and the current treatment options particularly in PAH, with special emphasis on prostanoids, endothelin receptor antagonists (ERAs), and phosphopdiesterase type 5 (PDE5) inhibitors such as sildenafil. Finally, novel developments are being discussed which currently represent an exciting field of research.

Syndrome d'emphysème des sommets et fibrose pulmonaire des bases combinés

A syndrome including upper-lobe emphysema and pulmonary fibrosis of the lower lungs was recently characterized. It is found most often in men who are smokers or ex-smokers of more than 40 pack-years; their mean age is 65 years. Exertional dyspnea is always present. There are basal crackles. The disease has no known cause; the only certain risk factor is smoking. Pulmonary function tests show respiratory volumes and flows that are often normal or subnormal, while carbon monoxide transfer is substantially reduced and exercise hypoxemia is present. Diagnosis is based on findings from millimeter-slices of computed tomography of the chest, which show either centrilobular emphysema or upper-zone bullous emphysema, associated in 90% of cases with very suggestive paraseptal emphysema and diffuse infiltrating fibrosing lung disease at the bases (subpleural reticular opacities, honeycomb images, traction bronchiectasis), with more frequent ground glass opacities than in idiopathic pulmonary fibrosis. Pulmonary hypertension is present in almost half of all patients and represents the principal negative prognostic factor for this condition, which has a median survival of 6 years.

Clinical perspective of hypoxia-mediated pulmonary hypertension

Pulmonary hypertension is a condition associated with a variety of pulmonary disorders whose common denominator is alveolar hypoxia. Such disorders include chronic obstructive pulmonary disease, pulmonary fibrosis, sleep-disordered breathing, and exposure to high altitude. Acute hypoxia is characterized by vasoconstriction of small pulmonary arteries, a phenomenon called hypoxic pulmonary vasoconstriction. With prolonged hypoxia, thickening of the smooth vascular layer of the small pulmonary arteries occurs, a phenomenon described as pulmonary vascular remodeling. Although the core mechanisms of both vasoconstriction and remodeling are thought to reside in the smooth muscle cell layer, the endothelium modulates these two processes. The purpose of this review is briefly to (a) discuss the mechanisms of hypoxic pulmonary hypertension as it pertains to certain disease states, and (b) examine the pathways that have potential therapeutic applications for this condition.

Treprostinil potentiates the positive inotropic effect of catecholamines in adult rat ventricular cardiomyocytes

BACKGROUND AND PURPOSE

Prostanoids have been shown to improve exercise tolerance, hemodynamics and quality of life in patients with pulmonary arterial hypertension (PAH). We investigated whether treprostinil exerts direct contractile effects on cardiomyocytes that may explain partly the beneficial effects of these drugs.

EXPERIMENTAL APPROACH

Ventricular cardiomyocytes from adult rats were paced at a constant frequency of 0.5 to 2.0 Hz and cell shortening was monitored via a cell edge detection system. Twitch amplitudes, expressed as percent cell shortening of the diastolic cell length, and maximal contraction velocity, relaxation velocity, time to peak of contraction and time to reach 50% of relaxation were analyzed.

KEY RESULTS

Treprostinil (0.15 - 15 ng ml(-1)) slightly increased contractile dynamics of cardiomyocytes at clinically relevant concentrations. However, the drug significantly improved cell shortening of cardiomyocytes in the presence of isoprenaline, a beta-adrenoceptor agonist. Treprostinil exerted this effect at all beating frequencies under investigation. Treprostinil mimicked this potentiating effect in a Langendorff preparation as well. The potentiating effect of treprostinil on isoprenaline-dependent cell shortening was no longer seen after phosphodiesterase inhibition. Long-term cultivation of cardiomyocytes with treprostinil did not modify load free cell shortening of these cells, but reduces the duration of contraction.

CONCLUSIONS AND IMPLICATIONS

We conclude that the clinically used prostanoid treprostinil potentiates the positive inotropic effects of catecholamines in adult ventricular cardiomyocytes. This newly described effect may contribute to the beneficial clinical effects of prostanoids in patients with PAH.

Pulmonary hypertension associated with chronic respiratory disease

Pulmonary hypertension (PH) has long been recognized as a complication of chronic respiratory disease. Recent studies have highlighted the adverse impact PH has on the clinical course of these conditions and have cast doubt on the role of hypoxia in their pathogenesis. Clinicians should carefully consider the possibility of PH during the diagnostic evaluation of chronic respiratory disorders. The usefulness of pharmacologic therapy directed toward PH remains to be determined.

Pulmonary hypertension in patients with interstitial lung diseases

Pulmonary hypertension (PH) in patients with interstitial lung diseases (ILDs) is not well recognized and can occur in the absence of advanced pulmonary dysfunction or hypoxemia. To address this topic, we identified relevant studies in the English language by searching the MEDLINE database (1966 to November 2006) and by individually reviewing the references of identified articles. Connective tissue disease-related ILD, sarcoidosis, idiopathic pulmonary fibrosis, and pulmonary Langerhans cell histiocytosis are the ILDs most commonly associated with PH. Pulmonary hypertension is an underrecognized complication in patients with ILDs and can adversely affect symptoms, functional capacity, and survival. Pulmonary hypertension can arise in patients with ILDs through various mechanisms, Including pulmonary vasoconstriction and vascular remodeling, vascular destruction associated with progressive parenchymal fibrosis, vascular inflammation, perivascular fibrosis, and thrombotic angiopathy. Diagnosis of PH in these patients requires a high index of suspicion because the clinical presentation tends to be nonspecific, particularly in the presence of an underlying parenchymal lung disease. Doppler echocardiography is an essential tool in the evaluation of suspected PH and allows ready recognition of cardiac causes. Right heart catheterization is needed to confirm the presence of PH, assess its severity, and guide therapy. Management of PH in patients with ILDs is guided by identification of the underlying mechanism and the clinical context. An increasing number of available pharmacologic agents in the treatment of PH allow possible treatment of PH in some patients with ILDs. Whether specific treatment of PH in these patients favorably alters functional capacity or outcome needs to be determined.

Idiopathic pulmonary fibrosis and pulmonary hypertension: connecting the dots

Idiopathic pulmonary fibrosis (IPF) has a poor prognosis and a course that is unpredictable. Pulmonary hypertension may complicate the course of IPF and potentially impact prognosis. There are multiple factors that might influence the onset and severity of pulmonary hypertension in IPF. The relationship between the physiologic and pathobiologic manifestations of the progressive fibrotic process and interceding pulmonary hypertension has not been well defined. This article serves to explore these relationships and to hypothesize about the possible linkage between these entities. From a prognostic standpoint, recent evidence suggests this to be important to assess for pulmonary hypertension in patients with IPF. The appropriate triggers for evaluating for pulmonary hypertension and the best method of detection require further study. Despite the relative ease of noninvasive methods, such as echocardiography, right-heart catheterization remains the best diagnostic test. The appeal of pulmonary hypertension in IPF is that it may be an enticing therapeutic target in a disease that otherwise does not have any proven effective therapies. Which agent(s) might be useful and when they should be implemented mandate the appropriate studies being performed. Some of the data presented in this article have previously been reported in abstract form only.

Scleroderma Lung

The lungs are frequently involved in systemic sclerosis ('scleroderma'), a rare, disabling disease of unknown origin, characterised by skin thickening and Raynaud's phenomenon. The pathogenesis of scleroderma is complex, but signs and symptoms of excessive fibrosis, vasculopathy and inflammation are almost universally present. Dyspnoea in scleroderma patients can be due to chest wall tightening from skin thickening, pleural disease, cardiac involvement, myositis of intercostal muscles, or so-called scleroderma lung disease. Scleroderma lung disease encompasses vascular (pulmonary artery hypertension) or interstitial lung disease, or both. A comprehensive work-up is required to delineate the underlying cause of dyspnoea in a scleroderma patient, and to establish the contribution of each component to the symptoms. This should include a 6-minute walk test, pulmonary function testing, high-resolution thoracic CT scanning, ECG, echocardiography and, if pulmonary artery hypertension is suspected, right-heart catheterisation; bronchoalveolar lavage is optional. Lung disease in scleroderma contributes significantly to excess morbidity and early mortality, especially when diffusion capacity drops below 40% and/or forced vital capacity below 50%. However, recent clinical studies have unequivocally demonstrated that scleroderma lung disease is amenable to treatment with new vasodilatory drugs that target specific pathways involved in vasoconstriction, or with cyclophosphamide for interstitial lung disease. Uncontrolled studies have suggested that these therapies also have an impact on survival, but controlled studies with a long follow-up are needed to corroborate this point.

Sarcoidosis-Associated Pulmonary Hypertension

RATIONALE

Pulmonary hypertension is a known complication of sarcoidosis and is associated with increased mortality. Little is known about the outcome of sarcoidosis-associated pulmonary hypertension, including response to treatment.

OBJECTIVE

To determine the characteristics and outcome of patients with sarcoidosis-associated pulmonary hypertension treated with IV epoprostenol.

DESIGN

Retrospective chart review of all cases of pulmonary hypertension with a concomitant diagnosis of sarcoidosis evaluated in the Boston University Pulmonary Hypertension Center from 2000 to 2004.

MEASUREMENTS

Data collected included patient demographics, sarcoidosis stage, pulmonary function, echocardiography results, treatment, baseline and posttreatment hemodynamic measurements, and clinical outcome.

RESULTS

Eight patients were identified; four of the patients had stage IV pulmonary sarcoidosis. Pulmonary function test results were notable for severe diffusion impairment (mean diffusion capacity of the lung for carbon monoxide, 30% of predicted), with only mild-to-moderate restrictive physiology (mean FVC, 59% of predicted). Seventy-five percent of patients required supplemental oxygen at the time of presentation. All patients had moderate or severe pulmonary hypertension and were New York Heart Association (NYHA)/World Health Organization (WHO) class III or IV. A vasodilator trial with epoprostenol was performed in seven of the eight patients; six of the seven patients had a significant hemodynamic response (> 25% reduction in pulmonary vascular resistance). All but one of the responders (five of six patients) continued on therapy. Average clinical improvement was one to two NYHA/WHO classes at a mean follow-up of 29 months (range, 15 to 49 months).

CONCLUSIONS

In patients with sarcoidosis-associated pulmonary hypertension, the severity of pulmonary vascular disease occurs out of proportion to lung function abnormalities. The majority of our patients responded to epoprostenol; survival may be improved in this group.

Endobronchial donor pre-treatment with ventavis: is a second administration during reperfusion beneficial to optimize post-ischemic function of non-heart beating donor lungs?

BACKGROUND

Lung retrieval from non-heart-beating donors (NHBD) has been introduced into clinical practice successfully. However, because of potentially deleterious effects of warm ischemia on microvascular integrity, use of NHBD lungs is limited by short tolerable time periods before preservation. Recently, improvement of NHBD graft function was demonstrated by donor pre-treatment using aerosolized Ventavis (Schering Inc., Berlin, Germany). Currently, there is no information whether additional application of this approach in reperfusion can further optimize immediate graft function.

MATERIAL AND METHODS

Asystolic pigs (n = 5/group) were ventilated for 180-min of warm ischemia (groups 1-3). In groups 2 and 3, 100 microg Ventavis were aerosolized over 30-min using an ultrasonic nebulizer (Optineb). Lungs were then retrogradely preserved with Perfadex and stored for 3-h. After left lung transplantation and contralateral lung exclusion, grafts were reperfused for 6-h. Only in group 3, another dose of 100 microg Ventavis was aerosolized during the first 30-min of reperfusion. Hemodynamics, pO2/FiO2 and dynamic compliance were monitored continuously and compared to controls. Intraalveolar edema was quantified stereologically, and extravascular-lung-water-index (EVLWI) was measured. Statistics comprised ANOVA analysis with repeated measurements.

RESULTS

Dynamic compliance was significantly lower in both Ventavis groups, but additional administration did not result in further improvement. Oxygenation, pulmonary hemodynamics, EVLWI and intraalveolar edema formation were comparable between groups.

CONCLUSIONS

Alveolar deposition of Ventavis in NHBD lungs before preservation significantly improves dynamic lung compliance and represents an important strategy for improvement of preservation quality and expansion of warm ischemic intervals. However, additional application of this method in early reperfusion is of no benefit.

Systemic and localized scleroderma

Sclerosing conditions of the skin are manifested by a full spectrum of presentations that includes skin-limited forms as well as those which can involve internal organs and result in death. At this point, we are just beginning to understand the mechanisms of tissue fibrosis, and it is likely that the fibrotic processes are a heterogeneous group of disorders in which perturbation of multiple molecular pathways, including vascular and immunologically mediated pathways, can lead to fibrosis. We now have some moderately effective therapies for vascular aspects of systemic sclerosis (eg, bosentan for pulmonary arterial hypertension, calcium-channel blockers for Raynaud's, or angiotensin-converting enzyme inhibitors for renal crisis). We also are beginning to find treatments interrupting the immunologic pathways that manifest as systemic sclerosis (eg, methotrexate for the skin or cyclophosphamide for the lungs). The basic process of fibrosis, however, awaits proven, effective therapy.

Comparison of Pharmacokinetics and Vasodilatory Effect of Nebulized and Infused Iloprost in Experimental Pulmonary Hypertension: Rapid Tolerance Development

Aerosolized iloprost has been suggested for selective pulmonary vasodilatation in severe pulmonary hypertension, but its pharmacokinetic profile is largely unknown. In perfused rabbit lungs, continuous infusion of the thromboxane mimetic U46619 was employed for establishing stable pulmonary hypertension. Delivery of a total amount of 75, 300, and 900 ng of iloprost to the bronchoalveolar space by a 10 min-aerosolization maneuver caused a dose-dependent pulmonary vasodilatation. Similarly, dose-dependent appearance of iloprost in the recirculating perfusate was noted, with maximum intravascular concentrations of iloprost ranging at 140, 510, and 1163 pg/mL at the same time period. Comparing pharmacokinetics and pharmacodynamics in a more detailed fashion, the following aspects were of interest. (i) The bioavailability (i.e., the percentage of aerosolized iloprost appearing intravascularly) decreased from 76% at the lowest to 33% at the highest iloprost dosage. (ii) The pulmonary vasodilatory response commenced already during the nebulization maneuver and preceded the perfusate entry of iloprost. (iii) After 3-3.5 h, the pulmonary vasodilatory response to aerosolized iloprost had virtually completely leveled off, whereas approximately two-thirds of the maximum iloprost perfusate levels were still detectable. A corresponding loss of vasodilatory response was also noted in experiments with continuous iloprost perfusion for clamping of the intravascular concentration of this prostanoid. We conclude that aerosolized iloprost causes dose-dependent vasodilatation and iloprost entry into the vascular space in a pulmonary hypertension model. Limited bioavailability in the higher dose range may suggest active prostanoid transport processes, and the early pulmonary vasodilatory response appears to be independent of prostanoid entry into the vessel lumen. Surprisingly, rapid tolerance development to the vasodilatory effect of iloprost is noted, occurring even with fully maintained perfusate levels of this agent.

Effects of nebulised iloprost on pulmonary function and gas exchange in severe pulmonary hypertension

Nebulised iloprost is established therapy of severe pulmonary hypertension; however, the effects on the bronchoalveolar compartment have not been investigated so far. We studied the short- and long-term effects of nebulised iloprost on pulmonary function tests and gas exchange in 63 patients with severe pulmonary hypertension (idiopathic n=17, chronic thromboembolism n=15, connective tissue disease n=12, congenital heart disease n=11, respiratory diseases n=8). Patients received iloprost in increasing dose up to 140 micro g iloprost/24h via an ultrasonic nebuliser. Short-term effects were assessed before and after every nebulisation: peak expiration flow decreased in mean by 1.9% (423+/-98 to 415+/-98) and percutaneous oxygen saturation increased in mean by 0.7% (90+/-6 to 91+/-5) post-nebulisation. There were no significant differences concerning underlying diagnosis or dose of nebulised iloprost. Within 3 months, 9 patients stopped treatment due to non-compliance with frequent nebulisations (n=3), or severe side effects (n=4); 2 patients with additional obstructive lung disease developed bronchoconstriction. Long-term effects were assessed by pulmonary function tests and gas exchange parameters at baseline and after 3 months treatment. There were no significant differences after 3 months therapy neither in FEV(1), FVC, TLC, residual volume nor in diffusions capacity, SO(2) at rest and during 6 min walking test, also in respect of the underlying diseases. However, there was a significant increase in 6 min walking distance (6 MWD) after 3 months (246+/-113 to 294+/-115 m, P<0.05). In conclusion, treatment with nebulised iloprost leads to functional improvement in severe pulmonary hypertension without systematic adverse short- and long-term effects on pulmonary function test or gas exchange. Patients with additional obstructive lung disease might develop bronchoconstriction. Severe side effects leading to discontinuation of treatment occurred in 9% of patients.

Iloprost inhalation solution for the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a condition that is characterised by increased pulmonary arterial pressure and vascular resistance that can lead to right ventricular failure and death. A variety of disturbances in pulmonary vascular endothelial and smooth muscle function are present in PAH, including reduced production of vasodilator and antiproliferative substances, such as nitric oxide and prostacyclin, and an overproduction of mitogens, such as endothelin. As a result of these observations, therapies have been developed for PAH that specifically target these pathogenic processes, including prostacyclin analogues and endothelin receptor antagonists. This article reviews iloprost inhalation solution, the most recently approved form of prostacyclin therapy that is delivered directly to the lungs by inhalation.

Brain Natriuretic Peptide Is a Prognostic Parameter in Chronic Lung Disease

RATIONALE

The detection of pulmonary hypertension in patients with chronic lung disease has prognostic implications. The brain natriuretic peptide (BNP) has been suggested as a noninvasive marker for the presence and severity of pulmonary hypertension.

OBJECTIVES

We evaluated circulating BNP levels as a parameter for the presence and severity of pulmonary hypertension in patients with chronic lung disease.

METHODS

BNP levels were measured in 176 consecutive patients with various pulmonary diseases. Right heart catheterization, lung functional testing, and a 6-min walk test were performed. The mean follow-up time was nearly 1 yr.

MEASUREMENTS AND MAIN RESULTS

Significant pulmonary hypertension (mean pulmonary artery pressure > 35 mm Hg) was diagnosed in more than one-fourth of patients and led to decreased exercise tolerance and life expectancy. Elevated BNP concentrations identified significant pulmonary hypertension with a sensitivity of 0.85 and specificity of 0.88 and predicted mortality. Moreover, BNP served as a risk factor of death independent of lung functional impairment or hypoxemia in uni- and multivariate analysis.

CONCLUSION

We suggest BNP as a prognostic marker and as screening parameter for significant pulmonary hypertension in chronic lung disease.

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.

Therapeutic Management of Idiopathic Pulmonary Fibrosis: An Evidence-Based Approach

The treatment of idiopathic pulmonary fibrosis (IPF) remains controversial. The benefits of conventional treatment with corticosteroids plus either azathioprine or cyclophosphamide have not been established in randomized, controlled trials. Other treatment strategies have been suggested as understanding of the pathogenesis of IPF has increased. Recent clinical and animal studies suggest that modulating the effects of profibrotic growth factors and cytokines holds significant promise. As additional well controlled prospective studies are completed, these trials should provide the clinical evidence necessary for identifying optimal treatment strategies for future patients who have IPF.

Treatment of pulmonary hypertension in patients undergoing cardiac surgery with cardiopulmonary bypass: a randomized, prospective, double-blind study

OBJECTIVE

Pulmonary hypertension can already be present in patients undergoing cardiac surgery or can be exacerbated by cardiopulmonary bypass. Postoperative treatment is still a challenge for physicians. The aim of this study was to evaluate the effects of inhaled prostacyclin (iPGI2) and nitric oxide (iNO) compared with those of intravenous vasodilators.

METHODS

This prospective, randomized, double-blind study included 58 patients affected by severe mitral valve stenosis and pulmonary hypertension with high pulmonary vascular resistance (> 250 dynes x s x cm(-5)) and a mean pulmonary artery pressure > 25 mmHg. All patients were monitored by central venous, radial arterial and Swan-Ganz catheters. Data were recorded at six different time points, before induction of anaesthesia, during and after surgery. Prostacyclin and nitric oxide were administered by inhalation 5 min before weaning from cardiopulmonary bypass and continued in the intensive care unit. Right ventricular function was evaluated by transoesophageal echocardiography.

RESULTS

Hospital mortality was 3.4%. After drug administration, the mean pulmonary artery pressure and pulmonary vascular resistance were significantly decreased in the iNO and iPGI2 groups with respect to the baseline values (P < 0.05) and such a decrease was maintained throughout the study; this was not observed in the control group. In the iNO and iPGI2 groups we demonstrated a significant increase in cardiac indices and right ventricular ejection fraction after drug administration with respect to baseline. Furthermore, patients in the inhaled drug groups were weaned easily from cardiopulmonary bypass (P = 0.04) and had a shorter intubation time (P = 0.03) and intensive care unit stay (P = 0.02) than the control group.

CONCLUSIONS

Our data suggest that both iNO and iPGI2 are effective in the treatment of pulmonary hypertension. iPGI2 has a number of advantages over iNO, including its easy administration and lower cost. Intravenous vasodilator treatment, on the other hand, is effective in terms of mortality but has a higher morbidity rate.

Pulmonary hypertension in interstitial lung disease

PURPOSE OF REVIEW

Exercise impairment and pulmonary hypertension are common features of interstitial lung disease. Antifibrotic therapies for interstitial lung disease remain unproved; therefore, some interest has been focused on treating the pulmonary vascular impairment these diseases.

RECENT FINDINGS

Patients with pulmonary hypertension secondary to idiopathic pulmonary fibrosis may have normal resting pulmonary artery pressure, but it often rises with exercise. Exercise impairment in idiopathic pulmonary fibrosis has a strong correlation with the degree of pulmonary artery pressure elevation, and hypoxemia, a hallmark of pulmonary hypertension, strongly correlates with survival.

SUMMARY

Small case series have shown that some patients improve on receiving therapy for pulmonary hypertension secondary to interstitial lung disease. These findings suggest that larger treatment trials for medications targeting pulmonary hypertension in interstitial lung disease are warranted.

Les traitements de l’hypertension artérielle pulmonaire à l’heure de la T2A. Recommandations du groupe de travail “Maladies vasculaires pulmonaires” de la Société de pneumologie de langue française

Activity-based financing (that is, casemix-based hospital payments, known as T2A) is intended to harmonize and improve the fairness of remuneration of public and private hospitals. T2A will ultimately rely mainly on a flat rate per admission, set according to the diagnosis-related group (DRG). Although payment for drugs is usually included in the DRG price, some expensive drugs will be reimbursed on an additional cost basis after implementation of a "best practices" agreement. Four drugs used for treatment of pulmonary arterial hypertension are eligible for this additional reimbursement: 3 prostacyclin derivatives (intravenous epoprostenol, inhaled iloprost, and subcutaneous treprostinil), and oral bosentan, an endothelin receptor antagonist. The Pulmonary Vascular Diseases working group of the French Society of Pulmonary Medicine has developed guidelines for the best practices in use of these drugs.

Pulmonary hypertension associated with sarcoidosis: mechanisms, haemodynamics and prognosis

BACKGROUND

Pulmonary hypertension (PH) is a rare complication of sarcoidosis, although it is not uncommon in advanced disease.

METHODS

A retrospective series of 22 sarcoidosis patients (16 men) of mean (SD) age 46 (13) years with PH was divided into two groups depending on the absence (stage 0: n = 2, stage II: n = 4, stage III: n = 1) or presence (n = 15) of radiographic pulmonary fibrosis at the time of PH diagnosis.

RESULTS

In both groups PH was moderate to severe and there was no response to acute vasodilator challenge. In non-fibrotic cases no other cause of PH was found, suggesting a specific sarcoidosis vasculopathy, although no histological specimens were available. In cases with fibrosis there was no correlation between haemodynamics and lung volumes or arterial oxygen tensions, suggesting other mechanisms for PH in addition to pulmonary destruction and hypoxaemia. These included extrinsic arterial compression by lymphadenopathies in three cases and histologically proven pulmonary veno-occlusive disease in the five patients who underwent lung transplantation. Ten patients received high doses of oral prednisone for PH (stage 0: n = 1, stage II: n = 4 and stage IV: n = 5); three patients without pulmonary fibrosis experienced a sustained haemodynamic response. Survival of the overall population was poor (59% at 5 years). Mortality was associated with NYHA functional class IV but not with haemodynamic parameters or with lung function.

CONCLUSION

Two very different phenotypes of sarcoidosis combined with PH are observed depending on the presence or absence of pulmonary fibrosis. PH is a severe complication of sarcoidosis.

Inhalative Pre-Treatment of Donor Lungs Using the Aerosolized Prostacyclin Analog Iloprost Ameliorates Reperfusion Injury

BACKGROUND

Lung transplantation is effective for end-stage pulmonary disease, but its successful application is still limited by organ shortage and sub-optimal preservation techniques. Therefore, optimal allograft protection is essential to reduce organ dysfunction, especially in the early post-operative period. Intravenous prostanoids are routinely used to ameliorate reperfusion injury. However, the latest evidence suggests similar efficacy using inhaled prostacyclin. Thus, we evaluated the impact of donor pre-treatment using the prostacyclin analog, iloprost, on post-ischemic function of Perfadex-protected allografts.

METHODS

In Group 1, 5 pig lungs were preserved with Perfadex (PER group) solution and stored for 27 hours. In Group 2, 100 microg of iloprost was aerosolized over 30 minutes using a novel mobile ultrasonic nebulizer (Optineb) before identical organ harvest (PER-ILO group). After left lung transplantation and contralateral lung exclusion, hemodynamic variables, Po2/Fio2 and dynamic compliance were monitored for 6 hours and compared with sham-operated controls. Pulmonary edema was determined stereologically and by wet-to-dry (W/D) weight ratio. Statistical assessment included analysis of variance (ANOVA) with repeated measures.

RESULTS

Dynamic compliance and pulmonary vascular resistance (PVR) were superior in iloprost-treated compared with untreated organs (p < 0.05), whereas oxygenation was comparable between groups. W/D ratio revealed a significantly smaller amount of lung water in PER-ILO organs (p = 0.048), whereas stereologic data showed a trend toward less intra-alveolar edema.

CONCLUSIONS

Endobronchial application of iloprost in donor lungs before Perfadex preservation decreases post-ischemic edema and significantly improves lung compliance and vascular resistance. This innovative approach is easily applicable in the clinical setting and offers a new strategy for improvement of pulmonary allograft preservation.

Current treatment strategies for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a disease characterized by an elevation in pulmonary artery pressure that can lead to right ventricular failure and death. Although there is no cure for PAH, newer medical therapies have been shown to improve a variety of clinically relevant end-points including survival, exercise tolerance, functional class, haemodynamics, echocardiographic parameters and quality of life measures. Since the introduction of continuous intravenous prostacyclin, the treatment armamentarium of approved drugs for PAH has expanded to include prostacyclin analogues with differing routes of administration, a dual endothelin receptor antagonist, and a phosphodiesterase-5 inhibitor. Selective endothelin-A receptor antagonists have shown promise in clinical trials and are likely to be added to the list of options. As the number of medications available for PAH continues to increase, treatment decisions regarding first-line therapy, combination treatments, and add-on strategies are becoming more complex. This article reviews the current treatments strategies for PAH and provides guidelines for its management.

Inhaled Iloprost in Pulmonary Arterial Hypertension

OBJECTIVE

To review the pharmacology, pharmacodynamics, and clinical trials evaluating inhaled iloprost in pulmonary arterial hypertension (PAH).

DATA SOURCES

A MEDLINE search (1996–February 2005) was performed using the key words pulmonary hypertension, iloprost, and epoprostenol. Information regarding Food and Drug Administration approval was obtained via the Internet.

STUDY SELECTION AND DATA EXTRACTION

All clinical trials using inhaled iloprost in PAH published in English were identified. Additionally, references from the identified articles were reviewed.

DATA SYNTHESIS

A stable analog of prostacyclin, inhaled iloprost is thought to promote benefit in PAH through vasodilation, antiproliferative effects, and inhibition of platelet aggregation. In a placebo-controlled trial of 203 patients, inhaled iloprost significantly improved the combined endpoint of change in New York Heart Association functional class and 10% improvement in 6-minute walk distance (p = 0.007). Small, short-term clinical trials demonstrated hemodynamic benefits for inhaled iloprost alone and in combination with other pulmonary vasodilating agents. The aerosolized delivery route and low incidence of adverse events are positive attributes for inhaled iloprost, while the frequency of administration and lack of comparative data limit its role in PAH.

CONCLUSIONS

Currently, inhaled iloprost offers potential benefit for patients with contraindications to bosentan, preference for non-parenteral products, ineligibility for parenteral therapy, or as adjunctive therapy with other pulmonary vasodilators. Larger, long-term clinical trials are needed to solidify the role for inhaled iloprost in the management of PAH.

An overview of pulmonary arterial hypertension: risks, pathogenesis, clinical manifestations, and management

This article focuses on pulmonary arterial hypertension, including both primary pulmonary hypertension (PPH) and those forms of pulmonary arterial hypertension that are related to other factors, including collagen vascular diseases, congenital shunts, portal hypertension, human immunodeficiency viral infection, and exposure to specific drugs and toxins. Risks for different types of pulmonary arterial hypertension are identified. The common pathogenesis for pulmonary arterial hypertension is discussed, and includes an overview of the role of key vasoactive substances such as nitric oxide, prostacyclin, endothelin, and thromboxane. Typical presenting clinical manifestations, recommendations for screening of patients at risk, and key diagnostic findings are discussed. The mainstay of treatment is identified as pharmacologic, and may include diuretics, digoxin, warfarin, calcium channel antagonists, and prostacyclin analogues such as epoprostenol. Surgical interventions are considered as a last resort, and may include unilateral or bilateral lung transplant or atrial septostomy. Treatment options for patients with pulmonary arterial hypertension hold more hope today than they did a decade ago and are identified so as to guide the advanced practice nurse in recognizing and then facilitating the appropriate management of patients with this rare but disabling disease.

[Drug treatments for idiopathic pulmonary fibrosis]

Idiopathic pulmonary fibrosis is a disease of unknown cause characterized by cough, progressive dyspnea, restrictive respiratory disorder, a typical honeycomb aspect on the high-resolution CT-scan, and usual interstitial pneumonia at histological examination of the lung biopsy. Most patients die 3 to 8 years after diagnosis. Current treatment is based on a combination of corticosteroids and immunosuppressants, but the efficacy of treatment remains a matter of debate. New therapeutics currently under evaluation in controlled clinical trials include interferon-gamma, pirfenidone, N-acetylcysteine, etanercept (anti-TNFalpha), bosentan (endothelin receptor antagonist), imatinib (tyrosine-kinases inhibitor of the PDGF receptor), etc. At the same time, new compounds showing efficacy in experimental models of fibrosis and the development of new pathophysiological concepts open new perspectives both in terms of concept and clinical practice.

Successful treatment with sildenafil in systemic sclerosis patients with isolated pulmonary arterial hypertension: two case reports

We describe two systemic sclerosis (SSc) patients with isolated pulmonary arterial hypertension (PAH) who were given treatment with 50 mg oral sildenafil per day. We evaluated the efficacy of oral sildenafil for isolated PAH in SSc patients by direct assessment with cardiac catheterization before and 6 months after the initiation of sildenafil. Right-heart catheterization demonstrated decreased mean pulmonary artery pressure, decreased pulmonary vascular resistance, and increased cardiac output after treatment with sildenafil. Brain natriuretic peptide levels were gradually decreased. The 6-min walking distance was greatly extended. Moreover, the physical conditions of both patients were much improved. We recognized no adverse events. We propose that oral sildenafil may be beneficial as a selective pulmonary vasodilator and as long-term treatment in SSc patients with isolated PAH.

Inhaled iloprost reverses vascular remodeling in chronic experimental pulmonary hypertension

RATIONALE

Inhaled iloprost is an effective therapy for pulmonary arterial hypertension (PAH). However, no study to date has addressed the effects of inhaled iloprost on changes to pulmonary vascular structure that occur in PAH.

OBJECTIVES

The present study was designed to investigate chronic antiremodeling effects of inhaled iloprost in monocrotaline (MCT)-induced PAH in rats.

METHODS

Four weeks after a single injection of MCT, after full establishment of PAH, rats were nebulized with iloprost at a dose of 6 microg . kg(-1) . day(-1), or underwent sham nebulization with saline.

RESULTS

After 2 weeks of inhalation therapy, right ventricular pressure and pulmonary vascular resistance were reversed in rats treated with iloprost, but not in sham-treated control animals. Systemic arterial pressure was unaffected. In addition, right heart hypertrophy, the degree of pulmonary artery muscularization, and the medial wall thickness of intraacinar pulmonary arteries regressed in response to iloprost. Furthermore, the MCT-induced increase in matrix metalloproteinase-2 and -9 activities and tenascin-C expression was suppressed.

CONCLUSIONS

We conclude that the inhalation of iloprost reverses PAH and vascular structural remodeling in MCT-treated rats. This regimen suggests the possibility of an antiremodeling therapy in PAH.

Prostacyclin for pulmonary hypertension in adults

BACKGROUND

Primary pulmonary hypertension (PPH) is progressive, resulting in right ventricular failure. Pulmonary hypertension can be idiopathic or associated with other conditions. Prostacyclin is a potent vasodilator and inhibitor of platelet aggregation, and can be given orally, subcutaneously, intravenously or inhaled via a nebuliser.

OBJECTIVES

To determine the efficacy of prostacyclin or one of its analogues in idiopathic primary pulmonary hypertension.

SEARCH STRATEGY

Electronic searches were carried out with pre-specified terms. Searches were current as of July 2004.

SELECTION CRITERIA

Two reviewers selected randomised controlled trials (RCTs) involving adults with pulmonary hypertension for inclusion.

DATA COLLECTION AND ANALYSIS

Study quality was assessed and data extracted independently by two reviewers. Outcomes were analysed as continuous and dichotomous outcomes. We sub-grouped data where possible by aetiology of PH (PPH, PH secondary to connective tissue disorder or mixed populations).

MAIN RESULTS

Nine RCTs of mixed duration (3 days-52 weeks), recruiting 1175 participants were included (NYHA functional classes II-IV). Intravenous prostacyclin versus usual care (four studies): There were significant improvements in exercise capacity of around 90 metres, cardiopulmonary haemodynamics and NYHA functional class over 3 days-12 weeks. Effects were consistent in primary and secondary pulmonary hypertension. Oral prostacyclin versus placebo (two studies): Short-term data (3-6 months) indicated that there was a significant improvement in exercise capacity, but data from one study of 52 weeks reported no significant difference at 12 months. No significant differences were observed for any other outcome. Subcutaneous treprostinil versus placebo (two studies, 8-12 weeks):One large study reported a significant median improvement in exercise capacity of around 16 metres. Cardiopulmonary haemodynamics and symptom scores favoured treprostinil. Infusion site pain and withdrawals due to adverse events were more frequent with treprostinil. Inhaled prostacyclin versus placebo (one study, 12 weeks):There was a significant increase in exercise capacity of approximately 36 metres. Treatment led to better symptom scores and functional class status than with placebo. Subgroup analyses reported by individual studies showed a better exercise capacity in participants with PPH, than those participants with PH secondary to other diseases. Side effects and adverse events were common in the studies.

AUTHORS' CONCLUSIONS

There is evidence that intravenous prostacyclin in addition to conventional therapy at tolerable doses optimised by titration, can confer some short-term benefits (up to 12 weeks of treatment) in exercise capacity, NYHA functional class and cardiopulmonary haemodynamics. There is also some evidence that patients with more severe disease based upon NYHA functional class showed a greater response to treatment.

Donor pretreatment using the aerosolized prostacyclin analogue iloprost optimizes post-ischemic function of non-heart beating donor lungs

BACKGROUND

Ischemia-reperfusion injury accounts for one-third of early deaths after lung transplantation. To expand the limited donor pool, lung retrieval from non-heart beating donors (NHBD) has been introduced recently. However, because of potentially deleterious effects of warm ischemia on microvascular integrity, use of NHBD lungs is limited by short tolerable time periods before preservation. After intravenous prostanoids are routinely used to ameliorate reperfusion injury, the latest evidence suggests similar efficacy of inhaled prostacyclin. Therefore, the impact of donor pretreatment with the prostacyclin analogue iloprost on postischemic NHBD lung function and preservation quality was evaluated.

METHODS

Asystolic pigs (5 per group) were ventilated for 180 minutes of warm ischemia (Group 2). In Group 3, 100 microg iloprost was aerosolized during the final 30 minutes of ventilation with a novel mobile ultrasonic nebulizer. Lungs were then retrogradely preserved with Perfadex and stored for 3 hours. After left lung transplantation and contralateral lung exclusion, hemodynamics, rO2/FiO2, and dynamic compliance were monitored for 6 hours and compared with sham-operated controls (Group 1). Pulmonary edema was determined both stereologically and by wet-to-dry weight ratio (W/D). Statistics comprised analysis of variance with repeated measures and Mann-Whitney test.

RESULTS

Flush preservation pressures, dynamic compliance, inspiratory pressures, and W/D were significantly superior in iloprost-treated lungs, and oxygenation and pulmonary hemodynamics were comparable between groups. Stereology revealed a trend toward lower intraalveolar edema formation in iloprost-treated lungs compared with untreated grafts.

CONCLUSIONS

Alveolar deposition of Iloprost and NHBD lungs before preservation ameliorates postischemic edema and significantly improves lung compliance. This easily applicable innovation approach, which uses a mobile ultrasonic nebulizer, offers an important strategy for improvement of pulmonary preservation quality and might expand the pool of donor lungs.

Medikament�se Therapie der pulmonalen Hypertonie

New drugs for pulmonary arterial hypertension have shown efficacy in randomized controlled trials. Endothelin receptor antagonists (ERA) and prostanoids are most important for clinical practice. Bosentan represents the first approved orally active therapy for PAH. Besides its hepatotoxicity it is mostly well tolerated. The first approved prostanoid, epoprostenol, is currently first choice only for decompensated right heart failure in PAH. It has to be delivered continuously intravenously and is prone to complications, side effects and very high costs. Alternatively, subcutaneous treprostinil can be applied. It is less risky and expensive but may cause local pain at the infusion site. Inhaled iloprost combines the features of a prostanoid with pulmonary and intrapulmonary selectivity. Alternatively, iloprost is being used as continuous intravenous infusion. The phosphodiesterase-5 inhibitor sildenafil was effective in two randomized controlled trials but has not been approved for PAH therapy.

Drug Treatment of Pulmonary Arterial Hypertension

During the last decade we have witnessed substantial improvements in the therapeutic options for pulmonary arterial hypertension (PAH), including true innovations targeting some of the mechanisms involved in the pathogenesis of this devastating disease. Intravenous epoprostenol was the first drug to improve symptoms and survival of patients with PAH. Novel prostanoids, including subcutaneous treprostinil and inhaled iloprost, also have beneficial effects in many patients, although their long-term efficacy is less well known. Among the newer treatments for PAH, endothelin receptor antagonists and phosphodiesterase type 5 (PDE5) inhibitors have reshaped clinical practice. The endothelin receptor antagonist bosentan has been approved in many parts of the world and most current guidelines recommend this drug as first-line treatment for patients with PAH in functional class III. Novel endothelin receptor antagonists such as sitaxsentan sodium and ambrisentan are currently being investigated. The PDE5 sildenafil is also being intensively studied in patients with pulmonary hypertension, and most of the available data look promising, although approval for PAH is still pending. Other PDE5 inhibitors have not yet undergone extensive study in PAH. The increasing insight into the pathogenesis of PAH opens several new therapeutic opportunities, which include vasoactive intestinal peptide, selective serotonin reuptake inhibitors, adrenomedullin and HMG-CoA reductase inhibitors (statins). However, PAH is a complex disorder and targeting a single pathway can not be expected to be uniformly successful. Thus, combining substances with different modes of action is expected to improve symptoms, haemodynamics and survival in PAH patients, although combination therapy has yet to undergo the scrutiny of large randomised clinical trials.

Brain Natriuretic Peptide and Exercise Capacity in Lung Fibrosis and Pulmonary Hypertension

Pulmonary hypertension (PH) can develop in lung fibrosis, and contributes to increased morbidity and mortality. Noninvasive parameters in the evaluation of PH in lung disease could aid in the management of these subjects. In this study, we aimed to characterize the role of brain natriuretic peptide (BNP) and the six-minute walk distance (6-MWD) in the assessment of pulmonary hypertension (PH) in subjects with lung fibrosis. Subjects with lung fibrosis and elevated BNP levels (n = 20) had significantly more severe PH during right heart catheterization than those with lung fibrosis, and normal BNP levels (mean pulmonary arterial pressure (40.85 +/- 3.2 mm Hg vs. 23.42+/-1.44 mm Hg, respectively) (n = 19) (p < 0.001). Significant correlations between lung volumes and BNP concentrations were not observed. A weak correlation existed between capillary pO(2) and 6-MWD (r = 0.42; p < 0.001). The presence of moderate-severe PH was associated with significant reduction of the 6-MWD. BNP concentrations predicted moderate-severe PH with 100% sensitivity and high specificity (89%). We conclude that BNP is an excellent marker for the presence of PH in patients with lung fibrosis. In addition, our data suggest that PH contributes significantly to exercise limitation in patients with severe lung fibrosis, raising the possibility that treatment of PH may be beneficial in these patients.

Prostanoid therapy for pulmonary arterial hypertension

Prostanoids have played a prominent role in the treatment of pulmonary arterial hypertension (PAH). Several compounds and methods of administration have been studied: chronic intravenously infused epoprostenol, chronic subcutaneously infused treprostinil, inhaled iloprost, and oral beraprost. Chronic intravenous epoprostenol therapy has had a substantial impact on the clinical management of patients with severe PAH. It improves exercise capacity, hemodynamics, and survival in patients with idiopathic pulmonary arterial hypertension (IPAH). It also improves exercise capacity and hemodynamics in patients with PAH occurring in association with scleroderma. The complexity of epoprostenol therapy (chronic indwelling catheters, reconstitution of the drug, operation of the infusion pump, and others) has led to attempts to develop other prostanoids with simpler modes of delivery. Treprostinil, a stable prostacyclin analogue with a half-life of 3 h, has been developed for subcutaneous delivery. It has beneficial effects on exercise and hemodynamics, which depend somewhat on the dose achieved. This, in turn, is determined by the patient's ability to tolerate the drug's side effects, including pain and erythema at the infusion site. Inhaled iloprost therapy may provide selectivity of the hemodynamic effects to the lung vasculature, thus avoiding systemic side effects. In a randomized and controlled trial, iloprost resulted in improvement in a combined end point incorporating the New York Heart Association functional class, 6-min walk test, and deterioration or death. Beraprost is the first orally active prostacyclin analogue. In the first of two randomized controlled trials, beraprost increased exercise capacity in patients with IPAH, with no significant changes in subjects with associated conditions. Hemodynamics did not change significantly, and no difference in survival was detected between the two treatment groups. The second study showed that beraprost-treated patients had less disease progression at six months and confirmed the results of the previous trial. However, this improvement was no longer present at 9 or 12 months. In conclusion, though treatment with prostanoids is complicated by their generally short half-lives and complicated drug delivery systems, they continue to play an important role in the treatment of PAH.

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.

Comparison of acute hemodynamic effects of aerosolized and intravenous iloprost in secondary pulmonary hypertension in children with congenital heart disease

Both aerosolized and intravenous infusion of iloprost caused a significant decrease in mean pulmonary artery pressure and pulmonary vascular resistance. Although intravenous infusion caused a large decrease in mean systemic arterial pressure, this was only slightly affected by aerosolized iloprost. Aerosolized iloprost caused a significant decrease in the pulmonary-to-systemic vascular resistance ratio; however, intravenous infusion did not cause a prominent decrease in this ratio.

Pharmacodynamics and Pharmacokinetics of Inhaled Iloprost, Aerosolized by Three Different Devices, in Severe Pulmonary Hypertension

BACKGROUND

Inhalation of iloprost, a stable prostacyclin analog, is an effective therapy for pulmonary hypertension with few side effects. This approach may, however, be handicapped by limitations of currently available nebulization devices. We assessed whether the physical characterization of a device is sufficient to predict drug deposition and pharmacologic effects.

METHODS

We investigated the effects of a standardized iloprost aerosol dose (5 micro g; inhaled within approximately 10 min) in 12 patients with severe pulmonary hypertension in a crossover design employing three well-characterized nebulizers. The nebulizers use different techniques to increase efficiency and alveolar targeting (Ilo-Neb/Aerotrap [Nebu-Tec; Elsenfeld, Germany], Ventstream [MedicAid; Bognor Regis, UK], and HaloLite [Profile Therapeutics; Bognor Regis, UK]). Measurements were performed using a Swan-Ganz catheter and determination of arterial iloprost plasma levels.

RESULTS

During inhalation of iloprost, the pulmonary vascular resistance decreased substantially (baseline, approximately 1,250 dyne.s.cm(-5); decrease, - 35.5 to - 38.0%) and pulmonary artery pressure decreased substantially (baseline, approximately 58 mm Hg; decline, - 18.4 to -21.8%), whereas the systemic arterial pressure was largely unaffected. Cardiac output and mixed venous and arterial oxygen saturation displayed a marked increase. The pharmacodynamic profiles with the three devices were superimposable. Moreover, rapid entry of iloprost into the systemic circulation was noted, peaking immediately after termination of the inhalation maneuver, with very similar maximum serum concentrations (158 pg/mL, 155 pg/mL, and 157 pg/mL), and half-lives of serum levels (6.5 min, 9.4 min, and 7.7 min) for the three nebulizers, respectively. Interestingly, the "half-life" of the pharmacodynamic effects in the pulmonary vasculature (eg, decrease in pulmonary vascular resistance, ranging between 21 and 25 min) clearly outlasted this serum level-based pharmacokinetic half-life.

CONCLUSIONS

A standardized dose of aerosolized iloprost delivered by different nebulizer types induces comparable pharmacodynamic and pharmacokinetic responses. Pulmonary vasodilation, persisting after disappearance of the drug from the systemic circulation, supports the hypothesis that local drug deposition largely contributes to the preferential pulmonary vasodilation in response to inhaled iloprost.

Pilot intervention: aerosolized adrenomedullin reduces pulmonary hypertension

In pulmonary hypertension, systemic infusion of adrenomedullin (ADM), a potent vasodilator peptide, leads to pulmonary vasodilatation. However, systemic blood pressure declines alike. The present study investigated the effect of aerosolized ADM on pulmonary arterial pressure in surfactant-depleted newborn piglets with pulmonary hypertension. Animals randomly received aerosolized ADM (ADM, n = 6), aerosolized ADM combined with intravenous application of NG-nitro-l-arginine methylester to inhibit nitric-oxide (NO) synthases (ADM + l-NAME, n = 5), or aerosolized normal saline solution (control, n = 6). Aerosol therapy was performed in 30-min intervals for 5 h. After a total experimental period of 8 h, mRNA expression of endothelial and inducible NO synthase and endothelin-1 (ET-1) in lung tissue was quantified using TaqMan real-time polymerase chain reaction. Aerosolized ADM reduced mean pulmonary artery pressure (MPAP) compared with control (p < 0.001; at the end of the study, Delta-MPAP -13.5 +/- 1.4 versus -6.2 +/- 2.4 mm Hg). PaO2 significantly increased in the ADM (DeltaPaO2 243.3 mm Hg) and the ADM + l-NAME group (DeltaPaO2 217.4 mm Hg) compared with the control group (DeltaPaO2 82.9 mm Hg; p < 0.001). Aerosolized ADM did not influence mean systemic arterial pressure (baseline 63.2 +/- 2.7 versus end of the study 66.3 +/- 6.5 mm Hg; not significant). NO synthases gene expressions were 20 to 30% lower with ADM compared with control. ET-1 gene expression was significantly reduced (>50%) after ADM aerosol therapy (p < 0.001). Aerosolized adrenomedullin significantly reduced MPAP without lowering the systemic arterial pressure and improved profoundly the arterial oxygen tension. This effect seems to be mediated at least in part by the reduction of ET-1.

Management of pulmonary hypertension resulting from interstitial lung disease

Pulmonary hypertension affects right ventricular function by imposing an afterload on the right ventricle and, therefore, as pulmonary hypertension worsens, it ultimately reduces cardiac output. It is clear that in interstitial lung disease, progression of the underlying process with the loss of lung parenchyma contributes substantially to outcome. However, the additional burden of pulmonary hypertension often results in rapid deterioration. Pulmonary hypertension may be treatable and thus may enable the patient to survive until other therapy is effective. Until recently, part of the hesitancy in treating pulmonary hypertension in patients with secondary pulmonary hypertension, has been the limited availability of oral or intravenous drugs that affect the pulmonary circuit without causing excessive systemic vasodilatation. The current drugs available for the treatment of pulmonary hypertension, including prostacyclin and endothelin receptor blockers, have been limited by their high costs and, in the case of prostacyclin, the drug delivery systems. Nitric oxide, which has been used both acutely and chronically for pulmonary hypertension in a variety of diseases, also has limited availability. The role of sildenafil and inhaled prostacyclin remains to be evaluated. The use of these agents in the setting of interstitial lung disease needs to be studied, including combination therapy and early initiation of therapy. Their effect on tissue damage, fibrosis, and inflammation needs to be assessed as well as their effect on the arteriopathy and their potential to cause ventilation-perfusion (V/Q) mismatching. There now appears to be evidence to support treating pulmonary hypertension in patients with interstitial lung disease, with a potential for clinical benefit and a molecular basis for doing it.

Oral sildenafil as long-term adjunct therapy to inhaled iloprost in severe pulmonary arterial hypertension

OBJECTIVES

We sought to investigate the impact of adjunct sildenafil on exercise capacity and hemodynamic parameters in patients with pulmonary arterial hypertension (PAH) who fulfilled predefined criteria of deterioration despite ongoing treatment with inhaled iloprost.

BACKGROUND

Inhaled iloprost is an effective therapy in PAH. The phosphodiesterase-5 inhibitor sildenafil exerts pulmonary vasodilation and may amplify prostanoid efficacy.

METHODS

Of 73 PAH patients receiving long-term inhaled iloprost treatment, 14 fulfilled criteria of deterioration unresponsive to conventional treatment. These patients received adjunct oral sildenafil over a period of nine to 12 months, leaving the inhalative iloprost regimen unchanged.

RESULTS

Before iloprost therapy, the baseline 6-min walking distance was 217 +/- 31 m (mean +/- SEM), with an improvement to 305 +/- 28 m within the first three months of iloprost treatment and a subsequent decline to 256 +/- 30 m after 18 +/- 4 months. Adjunct therapy with sildenafil reversed the deterioration and increased the 6-min walk distance to 346 +/- 26 m (p = 0.002, Wilcoxon test) at three months of combined therapy, with a sustained efficacy up to 12 months (349 +/- 32 m, p = 0.002). The distribution of New York Heart Association functional classes (IV/III/II) improved from September 9, 2000, before sildenafil, to January 8, 2003, after nine to 12 months with sildenafil. All hemodynamic variables changed favorably: pulmonary vascular resistance decreased from 2,494 +/- 256 before sildenafil to 1,950 +/- 128 dynes.s.cm(-5).m(2) after three months of adjunct sildenafil (p = 0.036). Two patients died of severe pneumonia during the period of combined therapy. No further serious adverse events occurred. CONCLUSIONS; In patients with severe PAH deteriorating despite ongoing prostanoid treatment, long-term adjunct oral sildenafil improves exercise capacity and pulmonary hemodynamics. A combination of prostanoids and sildenafil is an appealing concept for future treatment of pulmonary hypertension.

Transesophageal echocardiographic diagnosis of carbon dioxide embolism during minimally invasive saphenous vein harvesting and treatment with inhaled epoprostenol

IMPLICATIONS

We describe a patient scheduled for coronary artery bypass who developed carbon dioxide (CO2) embolism with acute pulmonary hypertension during endoscopic saphenectomy. Transesophageal echocardiography was useful in the diagnosis of CO2 embolism and to assess response to inhaled epoprostenol.

Subthreshold doses of nebulized prostacyclin and rolipram synergistaically protect against lung ischemia-reperfusion

BACKGROUND

Pulmonary edema caused by increased microvascular permeability is an important feature of lung ischemia-reperfusion (I/R) injury.

METHODS

We investigated the impact of co-aerosolized prostaglandin (PG)I(2) and the 3',5-cyclic adenosine monophosphate (cAMP)-specific phosphodiesterase inhibitor rolipram on microvascular leakage following I/R injury. Buffer-perfused rabbit lungs were exposed to 270 minutes of warm ischemia while anoxic ventilation and a positive intravascular pressure were maintained.

RESULTS

On reperfusion, a massive increase of the capillary filtration coefficient and severe edema formation were noted, whereas microvascular pressures displayed only minor changes. Short-time aerosolization of subthreshold doses of either rolipram (33 microg) or PGI(2) (2.6 microg) at the beginning of ischemia did not attenuate the leakage response, whereas the co-aerosolization of both agents largely blocked any permeability increase and edema formation, independent of hemodynamic effects. The same was true when the co-aerosolization was undertaken before onset of ischemia. Similarly, the intravascular administration of rolipram and PGI(2) showed a synergistic reduction of I/R-induced vascular leak but demanded 10-fold higher doses. Intravascular release of cAMP was markedly enhanced on combined PGI(2)-rolipram administration but depended on the mode of delivery of these agents.

CONCLUSIONS

Low doses of aerosolized prostacyclin and rolipram synergistically protect against severe lung I/R injury and can be used independently of lung perfusion. This strategy may be suitable for an improvement of organ preservation in lung transplantation including early management of non-heart-beating donors.

Inhaled epoprostenol (prostacyclin) and pulmonary hypertension before cardiac surgery

OBJECTIVE

Pulmonary hypertension is commonly found in patients undergoing valvular surgery and can be worsened by cardiopulmonary bypass. Inhaled epoprostenol (prostacyclin) has been used for the treatment of pulmonary hypertension, but its effects compared with those of placebo on hemodynamics, oxygenation, echocardiographic examination, and platelet function have not been studied during cardiac surgery.

METHODS

Twenty patients with pulmonary hypertension undergoing cardiac surgery were randomized in a double-blind study to receive inhaled epoprostenol (60 microg) or placebo. The inhalation occurred after induction of anesthesia and before surgical incision. The effects on left and right systolic and diastolic cardiac functions evaluated by means of pulmonary artery catheterization and transesophageal echocardiography, as well as oxygenation and platelet aggregation, were studied.

RESULTS

Inhalation of epoprostenol significantly reduced indexed right ventricular stroke work from 10.7 +/- 4.57 g. m. m(-2) to 7.8 +/- 3.94 g. m. m(-2) (P =.003) and systolic pulmonary artery pressure from 48.4 +/- 18 mm Hg to 38.9 +/- 11.9 mm Hg (P =.002). The effect was correlated with the severity of pulmonary hypertension (r = 0.76, P =.01) and was no longer apparent after 25 minutes. There was no significant effect on systemic arterial pressures, left ventricular function, arterial oxygenation, platelet aggregation, and surgical blood loss.

CONCLUSION

Inhaled epoprostenol reduces pulmonary pressure and improves right ventricular stroke work in patients with pulmonary hypertension undergoing cardiac surgery. A dose of 60 microg is hemodynamically safe, and its effect is completely reversed after 25 minutes. We did not observe any evidence of platelet dysfunction or an increase in surgical bleeding after administration of inhaled epoprostenol.

Prostacyclin for pulmonary hypertension

BACKGROUND

Primary pulmonary hypertension (PPH) is progressive, resulting in right ventricular failure. Survival seldom exceeds five years. Pulmonary hypertension can be idiopathic or associated with other conditions. It is common in patients with diffuse scleroderma and the CREST syndrome where it is clinically, haemodynamically and prognostically indistinguishable from idiopathic primary pulmonary hypertension. Prostacyclin is a potent vasodilator and inhibitor of platelet aggregation. Iloprost is a chemically stable derivative of prostacyclin with similar biologic properties and can be given orally, by infusion or nebulised.

OBJECTIVES

To determine the efficacy of prostacyclin or one of its analogues in idiopathic primary pulmonary hypertension.

SEARCH STRATEGY

A search was carried out using the Cochrane controlled clinical trial register. An update search was conducted on 12th August 2002. Four new trials met the inclusion criteria of the review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) involving patients with primary pulmonary hypertension or pulmonary hypertension secondary to connective tissue disorders were selected by two reviewers.

DATA COLLECTION AND ANALYSIS

Study quality was assessed and data extracted independently by two reviewers. Outcomes were analysed as continuous and dichotomous outcomes, using standard statistical techniques.

MAIN RESULTS

Seven RCTs of short duration (8-12 weeks) were included. Three compared intravenous epoprostenol with conventional therapy. One compared intravenous Iloprost with placebo. One RCT compared oral prostacyclin with placebo, another compared subcutaneous infusion of treprostinil with placebo and a further RCT studied the effects of inhaled iloprost. All the trials showed an improvement in exercise capacity. Cardiopulmonary haemodynamics, dyspnoea scores and symptoms also improved in some of the studies. Side effects and adverse events related to the indwelling catheter (sepsis and thrombosis) were common in intravenous trials. The other routes of administration had less severe side effects.

REVIEWER'S CONCLUSIONS

Intravenous prostacyclin or one of its analogues in addition to conventional therapy over 12 weeks appears to improve exercise capacity, NYHA functional class and several cardiopulmonary haemodynamic variables. There is some evidence that other routes of administration of the drug may also be effective with fewer side effects, which were mainly related to the indwelling catheter.

Inhaled prostacyclin for the treatment of pulmonary hypertension after cardiac surgery

OBJECTIVE

To describe the effects of inhaled prostacyclin administered after cardiopulmonary bypass (CPB) to a patient with severe pulmonary hypertension.

DESIGN

Case report and literature review.

SETTING

Cardiac surgical operating rooms and postoperative recovery unit.

PATIENTS

A 63-yr-old female who had undergone mitral and aortic valve replacement for rheumatic heart disease.

INTERVENTIONS

Administration of inhaled prostacyclin to decrease pulmonary artery pressures and to permit discontinuation of CPB.

MEASUREMENTS AND MAIN RESULTS

The patient was unable to be removed from CPB because of severe pulmonary hypertension precipitating acute right heart failure, despite administration of milrinone, norepinephrine, and nitroglycerin infusions. Inhaled prostacyclin was started at a dosage of 50 ng/kg/min, and the patient was able to be weaned from CPB. The inhaled prostacyclin was continued for 4 days postoperatively, with no signs of tolerance or systemic effects.

CONCLUSION

Inhaled prostacyclin is an effective and selective pulmonary vasodilator at the dosage given in this report. Prolonged use is not associated with tolerance or systemic effects. The apparatus required for the delivery of inhaled prostacyclin is simple, inexpensive, and readily available in most hospitals. A review of the literature suggests that inhaled prostacyclin is effective in a number of clinical settings and displays comparable efficacy and hemodynamic effects to inhaled nitric oxide.

Pharmacokinetics and metabolism of infused versus inhaled iloprost in isolated rabbit lungs

Iloprost is a potent prostacyclin analog, which has been shown to exert beneficial effects in several vascular disorders. Inhalation of aerosolized iloprost was found to cause selective pulmonary vasodilatation, and this approach is under current investigation for treatment of chronic pulmonary hypertension. The present study investigated pharmacokinetics and metabolism of aerosolized iloprost in isolated buffer-perfused rabbit lungs, compared with intravascular administration of the prostanoid. After buffer admixture of iloprost, a steady decline of perfusate concentrations of the intact prostanoid was noted (half-life approximately 3.5 h), mostly attributable to progressive metabolism to dinor- and tetranoriloprost. Inhaled iloprost rapidly entered the intravascular compartment, with peak buffer concentrations being noted after 30 min (bioavailability approximately 63%). Compared with infused iloprost, significantly more rapid metabolism to dinor- and tetranoriloprost was noted for iloprost administered via the inhalative route of application. However, the percentage of the nebulized agent that enters the intravascular space as intact iloprost displays the same clearance rate as directly perfusate-admixed prostanoid. We conclude that a high percentage of inhaled iloprost rapidly enters the intravascular compartment in intact rabbit lungs. The lung is capable of metabolizing iloprost via beta-oxidation, and more rapid appearance of dinor- and tetranoriloprost is noted for the inhalative as compared with the intravascular route of iloprost administration.

Emerging medical therapies for pulmonary arterial hypertension

Until a few years ago, "conventional" treatment for pulmonary arterial hypertension (PAH) included oral anticoagulants, calcium channel blockers, diuretics, digoxin, and oxygen. In the 1990s, 3 randomized studies demonstrated that the continuous intravenous infusion of epoprostenol improved functional capacity, cardiopulmonary hemodynamics, and survival in patients with severe PAH. Recently, the thromboxane inhibitor terbogrel, the prostacyclin analogues treprostinil, beraprost, and iloprost, and the endothelin receptor antagonist bosentan have been tested in clinical trials in more than 1,100 patients. Except for terbogrel, all compounds have improved by different degrees the mean exercise capacity as assessed by 6 minutes walking distance. Conversely, these trials differ for the severity and etiology of included PAH patients as well as for the effects on combined clinical events, on quality of life, and on hemodynamics. No trials have shown effects on mortality, and each new compound presents different side effects that seem unpredictable in the individual patient. At present, additional new compounds such as sitaxentan, ambisentan, L-arginine, and sildenafil are studied in clinical trials. The new therapeutic options are currently in different phases of approval by regulatory agencies, and when they will become available we will have the opportunity to select the most appropriate treatment for the single patient, according to an individualized benefit-to-risk ratio.