[Right heart failure in chronic pulmonary hypertension and acute pulmonary embolism]. / Rechtsherzversagen bei chronischer pulmonaler Hypertonie und akuter Lungenembolie.

Right-sided heart failure is a severe and often life-threatening complication of chronic pulmonary hypertension. The detection of trigger factors that induce right heart failure in previously stable patients is important to initiate a causal therapeutic strategy. Pulmonary embolism (PE) is a frequent cause of acute right heart failure and therapeutic strategies for PE are well documented in the current guidelines. Treatment of choice for chronic thromboembolic pulmonary hypertension (CTEPH) is surgical pulmonary endarterectomy (PEA) and patients with possible CTEPH should be referred to an experienced PEA surgeon without delay. Intensive care management for overt right heart failure is complex and includes the use of pulmonary vasodilators, individual adjustment of diuretic or volume therapy, augmentation of myocardial contractility and left ventricular afterload. Therapeutic regimens aim at optimized filling of the right ventricle, improvement of myocardial perfusion by avoiding tachycardia, elevating systemic pressure and reducing right ventricular afterload. Early communication with a specialized center for pulmonary hypertension is recommended.

[Pulmonary arterial hypertension]. / Pulmonalarterielle Hypertonie.

Pulmonary arterial hypertension is a chronic disorder of the pulmonary circulation characterized by an increased pulmonary artery pressure and an impaired cardiac function. It can present as idiopathic form or associated with several systemic diseases. Typical symptoms include progressive dyspnoea and exercise intolerance. When pulmonary arterial hypertension is suspected, echocardiography is the key investigation for noninvasive assessment of the disease. The diagnosis requires an invasive measurement of pulmonary hemodynamics by right heart catheterization. Treatment is based on general measures and application of pulmonary vasoactive compounds, such as prostanoids, endothelin receptor blockers and phosphodiesterase 5 inhibitors. These treatment options can be combined at progression of the disease. Lung transplantation might be an option in patients refractory to medical therapy.

Stem cell-mediated natural tissue engineering.

Recently, we demonstrated that a fully differentiated tissue developed on a ventricular septal occluder that had been implanted due to infarct-related septum rupture. We suggested that this tissue originated from circulating stem cells. The aim of the present study was to evaluate this hypothesis and to investigate the physiological differentiation and transdifferentiation potential of circulating stem cells. We developed an animal model in which a freely floating membrane was inserted into each the left ventricle and the descending aorta. Membranes were removed after pre-specified intervals of 3 days, and 2, 6 and 12 weeks; the newly developed tissue was evaluated using quantitative RT-PCR, immunohistochemistry and in situ hybridization. The contribution of stem cells was directly evaluated in another group of animals that were by treated with granulocyte macrophage colony-stimulating factor (GM-CSF) early after implantation. We demonstrated the time-dependent generation of a fully differentiated tissue composed of fibroblasts, myofibroblasts, smooth muscle cells, endothelial cells and new blood vessels. Cells differentiated into early cardiomyocytes on membranes implanted in the left ventricles but not on those implanted in the aortas. Stem cell mobilization with GM-CSF led to more rapid tissue growth and differentiation. The GM-CSF effect on cell proliferation outlasted the treat ment period by several weeks. Circulating stem cells contributed to the development of a fully differentiated tissue on membranes placed within the left ventricle or descending aorta under physiological conditions. Early cardiomyocyte generation was identified only on membranes positioned within the left ventricle.

[Treatment of pulmonary arterial hypertension (PAH): recommendations of the Cologne Consensus Conference 2010]. / Therapie der pulmonal arteriellen Hypertonie (PAH): Empfehlungen der Kölner Konsensus-Konferenz 2010.

The 2009 European Guidelines on Diagnosis and Treatment of Pulmonary Hypertension have been adopted for Germany. The guidelines contain detailed recommendations for the treatment of pulmonary arterial hypertension (PAH). However, the practical implementation of the European Guidelines in Germany requires the consideration of several country-specific issues and already existing novel data. This requires a detailed commentary to the guidelines, and in some aspects an update already appears necessary. In June 2010, a Consensus Conference organized by the PH working groups of the German Society of Cardiology (DGK), the German Society of Respiratory Medicine (DGP) and the German Society of Pediatric Cardiology (DGPK) was held in Cologne, Germany. This conference aimed to solve practical and controversial issues surrounding the implementation of the European Guidelines in Germany. To this end, a number of working groups was initiated, one of which was specifically dedicated to the treatment of PAH. This commentary summarizes the results and recommendations of the working group on treatment of PAH.

Treprostinil inhibits the recruitment of bone marrow-derived circulating fibrocytes in chronic hypoxic pulmonary hypertension.

A unique subpopulation of peripheral blood mononuclear cells that exhibit a parallel expression of haematopoietic and mesenchymal markers has been described as "circulating fibrocytes". These cells were demonstrated to obtain a fibroblastic phenotype in tissues or cell culture and contribute to pulmonary fibrotic disorders and tissue remodelling processes. The aim of our study was to characterise the recruitment of circulating fibrocytes in vivo in the model of chronic hypoxic pulmonary hypertension in mice and to analyse the therapeutic effect of the stable prostacyclin analogue trepostinil with respect to this cell population. To track circulating fibrocytes in vivo, we transplanted wild-type mice with bone marrow from ubiquitously eGFP expressing mice and subjected them to chronic hypoxia. We observed significantly increased recruitment of circulating fibrocytes to the remodelled pulmonary resistance arteries in response to hypoxia. Treatment with treprostinil significantly reduced the recruitment of these cells compared to normoxic mice. Treprostinil also reduced right ventricular systolic pressure and slightly reduced the vascular remodelling but failed to reverse the right ventricular hypertrophy. In summary, we show that circulating fibrocytes contribute to hypoxic pulmonary vascular remodelling and may be specifically targeted by a prostacyclin analogue. Further investigations of cellular and paracrine mechanisms are warranted to decipher their role in pulmonary hypertension.

Epoxyeicosatrienoates are the dominant eicosanoids in human lungs upon microbial challenge.

Lipoxygenase, cyclo-oxygenase and cytochrome P450 (CYP) products of arachidonic acid (AA) are implicated in pulmonary vasoregulation. The CYP-mediated epoxyeicosatrienoates (EETs) have been described previously as the predominant eicosanoids in human lungs upon stimulation with the Ca(2+) ionophore A23187. In this study, we challenged perfused human lungs with two microbial agents: Escherichia coli haemolysin (ECH) and formyl-methionyl-leucyl-phenylalanine (fMLP). Both stimuli elicited pronounced generation of leukotrienes (LTs), hydroxyeicosatetraenoic acids (HETEs), prostanoids (PTs) and EETs/dihydroxyeicosatrienoic acids (DHETs), as assessed by liquid chromatography-mass spectrometry, paralleled by pulmonary artery pressor response and lung oedema formation. The maximum buffer concentrations of EETs/DHETs surpassed those of LTs plus HETEs and PTs by a factor of four (ECH) or three (AA/fMLP). Dual 5-lipoxygenase/cyclo-oxygenase inhibition caused pronounced reduction of AA/fMLP-induced LT/PT synthesis and oedema formation but only limited attenuation of pulmonary vasoconstriction, while inhibition of CYP epoxygenase clearly attenuated AA/fMLP-induced EET/DHET synthesis and vasoconstriction but not oedema formation, suggesting a major contribution of LTs/PTs to vascular leakage and of EETs/DHETs to pressor response. Consequently, generation of EETs/DHETs is greater than that of LTs plus HETEs and PTs in ex vivo perfused human lungs upon microbial challenge suggesting a substantial contribution of these mediators to inflammatory-infectious pulmonary injury.

Comparative gene expression profiling of post-natal and post-pneumonectomy lung growth.

Although increasing numbers of patients suffer from chronic destructive lung diseases, there are no effective therapeutic options apart from transplantation. Understanding the mechanisms of physiological and regenerative alveolar septation is prerequisite for the development of regenerative therapies for the lung. We compared lung gene expression in the phase of induction of post-natal and post-pneumonectomy alveolarisation to identify regulatory genes involved in both processes. We performed genome-wide microarray screenings of newborn and pneumonectomised mouse lungs 1 and 3 days after birth or surgery. Selected candidates were validated by real-time PCR, Western blot and in situ hybridisation. We found 58 genes to be regulated in both models with 40 candidates being changed likewise. Many of these genes participated in growth and differentiation processes. Additionally, immune system, structural molecules, respiratory chain, signal transduction and metabolism were involved. Some candidates were not yet linked to specific functions. The highest regulatory concordance was observed for various isoforms of (pro-)collagen molecules, elastin and the elastin-associated protein fibrillin1 being corporately upregulated. Our findings do not definitively support a common regulating mechanism for induction of post-natal and adult alveolarisation, but some candidates in the intersection of both models are promising for further investigations.

[Pulmonary hypertension in hereditary haemorrhagic teleangiectasia]. / Pulmonalvaskuläre Beteiligung bei Morbus Osler.

BACKGROUND: In hereditary haemorrhagic teleangiectasia (HHT) can be accompanied by pulmonary arteriovenous vascular malformations (PAVM). Pulmonary hypertension (PH) is regarded as a rare pulmonary manifestation. METHODS AND PATIENTS: We non-invasively assessed the pulmonary circulation in 20 patients with HHT using standard resting echocardiography including contrast studies. In 14 patients a mutation in the endoglin gene was present. The other 6 patients carried a mutation in the Alk-1 gene. RESULTS: We identified 4 patients with manifest PH, among them 2 patients (both with endoglin mutations) with concurrent thromboembolism, and 2 patients (both with Alk-1 mutations) with hepatic manifestations of HHT. Two patients required specific pulmonary vasoactive therapy with sildenafil and bosentan, respectively. Another patient received embolisation therapy for hypercirculatory PH due to hepatic arteriovenous malformations. Pulmonary arteriovenous malformations were found in 8 patients (7 with endoglin, and 1 with Alk-1 mutations), among them were 2 patients with PH. CONCLUSIONS: Patients with HHT should undergo echocardiographic screening for PAVM as well as PH. When PH is detected, other conditions such as hepatic or thromboembolic diseases should be considered, regardless of the underlying genetic defect.

[Therapy of pulmonary arterial hypertension]. / Therapie der pulmonalarteriellen Hypertonie.

Current international guidelines on the treatment of pulmonary arterial hypertension (PAH) are compiled by the European Society of Cardiology and the American College of Chest Physicians. The classification of pulmonary hypertension and guidelines on diagnosis and therapy were last adopted at the 4th World Congress of PAH in Dana Point (California) in the year 2008. Based on these guidelines this article presents an overview of the current therapy recommendations for patients with PAH corresponding to group 1 of the diagnostic WHO classification of pulmonary hypertension. Here it is recommended that diagnostic and therapy should be carried out in an expert centre. The therapy forms for PAH can be classified into basic therapy (e. g. oral anticoagulants, diuretics and oxygen therapy) and specific therapy (e. g. phosphodiesterase-5 inhibitors, endothelin receptor antagonists and prostanoids). Finally, some new substances will be presented which have already progressed relatively far in the clinical development.

Noninvasive detection of early pulmonary vascular dysfunction in scleroderma.

BACKGROUND: Pulmonary arterial hypertension is a serious complication in scleroderma and early diagnosis is warranted. PATIENTS AND METHODS: 33 Scleroderma patients (mean age 54 [SD 11] years) with normal systolic pulmonary artery pressure (sPAP), right and left ventricular parameters at rest were enrolled in this study. They were investigated by echocardiography during physical exercise and hypoxia. A hypertensive pulmonary vascular reaction was diagnosed when sPAP inappropriately increased during exercise compared to individual exercise tolerance, or if sPAP was >40mm Hg during hypoxia exposure, respectively. RESULTS: In 17 patients there was a normal increase of sPAP at exercise of 34 [8]mm Hg (mean VO2 max 70 [17]% predicted), and 29 [5]mm Hg during hypoxia. Sixteen patients developed a hypertensive pulmonary vascular response with a sPAP of 47 [9]mm Hg during exercise (VO2max 64 [15]% pred.), and 54 [7]mm Hgmm Hg during hypoxia, respectively. The sPAP/VO2 max ratio was higher in patients with a hypertensive response (0.76 [0.17] vs. 0.49 [0.12] p<0.0001). There was no difference in scleroderma subtype, duration of disease, gender or age between groups. During a 3-year follow up one patient with a hypertensive response developed manifest pulmonary arterial hypertension. CONCLUSION: Non-invasive assessment of pulmonary circulation during physical exercise and/or hypoxia enables screening for pulmonary vascular dysfunction in scleroderma.

First acute haemodynamic study of soluble guanylate cyclase stimulator riociguat in pulmonary hypertension.

Pulmonary hypertension (PH) is associated with impaired production of the vasodilator nitric oxide (NO). Riociguat (BAY 63-2521; Bayer Healthcare AG, Wuppertal, Germany) acts directly on soluble guanylate cyclase, stimulating the enzyme and increasing sensitivity to low NO levels. The present study evaluates riociguat safety, tolerability and efficacy in patients with moderate-to-severe PH (pulmonary arterial hypertension, distal chronic thromboembolic PH or PH with mild to moderate interstitial lung disease). The optimal tolerated dose was identified by incremental dosing in four patients with PH; pharmacodynamic and pharmacokinetic parameters were assessed following single-dose administration (2.5 mg or 1 mg) in 10 and five patients with PH, respectively. All subjects (n = 19) were analysed for safety and tolerability. Riociguat had a favourable safety profile at single doses < or =2.5 mg. It significantly improved pulmonary haemodynamic parameters and cardiac index in patients with PH in a dose-dependent manner, to a greater extent than inhaled NO. Although riociguat also had significant systemic effects and showed no pulmonary selectivity, mean systolic blood pressure remained >110 mmHg. The present report is the first to describe the use of riociguat in patients with pulmonary hypertension. The drug was well-tolerated and superior to nitric oxide in efficacy and duration. Riociguat, therefore, has potential as a novel therapy for pulmonary hypertension and warrants further investigation.

Neoalveolarisation contributes to compensatory lung growth following pneumonectomy in mice.

Regeneration of the gas exchange area by induction of neoalveolarisation would greatly improve therapeutic options in destructive pulmonary diseases. Unilateral pneumonectomy is an established model to remove defined portions of gas exchange area and study mechanisms of compensatory lung growth. The question of whether new alveoli are added to the residual lung after pneumonectomy in mice was addressed. Left-sided pneumonectomy was performed in 11 adult C57BL/6 mice. Alveolar numbers were analysed in lungs fixed at days 6 and 20 after pneumonectomy and in 10 age-matched controls using design-based stereology based on a physical fractionator. Post-fixation lung volume was determined by fluid displacement. Complete restoration of lung volume was observed 20 days after pneumonectomy. Alveolar numbers were significantly increased by 33% in residual right lungs at day 20 in comparison with control right lungs. In control left lungs, an average of 471+/-162 x 10(3) alveoli was estimated, 49% of which were regenerated by residual lungs at day 20. Of the newly formed alveoli seen at day 20, 74% were already present at day 6. The present data demonstrate that, in addition to growth in size of existing alveoli, neoalveolarisation contributes to restoration of the gas exchange area in adult mice and is induced early after pneumonectomy.

Long-term treatment with sildenafil in chronic thromboembolic pulmonary hypertension.

For chronic thromboembolic pulmonary hypertension not amenable to pulmonary endarterectomy, effective medical therapy is desired. In an open-label uncontrolled clinical trial, 104 patients (mean +/- sem age 62 +/- 11 yrs) with inoperable chronic thromboembolic pulmonary hypertension were treated with 50 mg sildenafil t.i.d. At baseline, patients had severe pulmonary hypertension (pulmonary vascular resistance 863 +/- 38 dyn.s.cm(-5)) and a 6-min walking distance of 310 +/- 11 m. Eight patients were in World Health Organization functional class II, 76 in class III and 20 in class IV. After 3 months' treatment, there was significant haemodynamic improvement, with reduction of pulmonary vascular resistance to 759 +/- 62 dyn.s.cm(-5). The 6-min walking distance increased significantly to 361 +/- 15 m after 3 months' treatment, and to 366 +/- 18 m after 12 months' treatment. A subset of 67 patients received a single dose of 50 mg sildenafil during initial right heart catheterisation. The acute haemodynamic effect of this was not predictive of long-term outcome. In this large series of patients with inoperable chronic thromboembolic pulmonary hypertension, open-label treatment with sildenafil led to significant long-term functional improvement. The acute effect of sildenafil may not predict the long-term outcome of therapy.

Sildenafil treatment for portopulmonary hypertension.

Portopulmonary hypertension (POPH) is regarded as a subtype of pulmonary arterial hypertension (PAH); however, established PAH therapies have not been evaluated for this condition. The current authors treated 14 patients (four male, 10 female; mean (range) age 55 (39-75) yrs) with moderate (n = 1) or severe (n = 13) POPH caused by alcoholic liver disease (n = 7), chronic viral hepatitis (n = 3), autoimmune hepatitis (n = 3), and hepatic manifestation of hereditary haemorrhagic teleangiectasia (n = 1) with oral sildenafil. Eight patients were newly started on pulmonary vasoactive treatment, while six patients were already on treatment with inhaled prostanoids (iloprost, n = 5; treprostinil, n = 1). During treatment with sildenafil, mean +/- sd 6-min walk distance increased from 312 +/- 111 m to 397 +/- 99 m after 3 months, and 407 +/- 97 m after 12 months. Mean +/- sd pro-brain natriuretic peptide levels decreased from 582 +/- 315 ng x mL(-1) to 230 +/- 278 ng x mL(-1), and to 189 +/- 274 ng x mL(-1) after 3 and 12 months, respectively. Two patients died after 1 and 2 months from liver failure and cardiac failure, respectively. There was a similar response to sildenafil treatment after 3 and 12 months in patients on monotherapy and those on combination therapy. In conclusion, sildenafil might be effective in monotherapy and in combination therapy with inhaled prostanoids in portopulmonary hypertension, leading to significant improvement by 3 months and sustained response over 12 months.

Sildenafil improves dynamic vascular function in the brain: studies in patients with pulmonary hypertension.

BACKGROUND: Prostaglandins and nitric oxide play a pivotal role in the regulation of macro- and microcirculatory blood flow distribution. Interference with both mediator systems have been implicated in cerebrovascular dysfunction. Inhaled iloprost (long-acting prostacyclin analogue) and the phosphodiesterase-5 inhibitor sildenafil have recently shown efficacy in the treatment of chronic pulmonary hypertension. We investigated the impact of these agents on cerebral microcirculatory regulation in patients suffering from this disease. METHODS: In 11 patients suffering from severe pulmonary hypertension, a functional transcranial Doppler test utilizing a visual stimulation paradigm was undertaken to measure the evoked flow velocity in the posterior cerebral artery. Measurements were performed in parallel to right heart catheterization and pharmacological testing of the pulmonary vasoreactivity. After assessment of baseline measurements, inhaled iloprost and oral sildenafil were given consecutively for testing of cerebral and pulmonary vascular function. The data gained from the Doppler measurements were compared to data from 22 healthy volunteers. RESULTS: Both substances provoked a significant reduction of pulmonary arterial pressure and vascular resistance, accompanied by minor changes in systemic vascular resistance. In contrast to these superimposable hemodynamic profiles opposite effects were observed regarding cerebral vascular tone: cerebral microvascular reactivity, as assessed by attenuation and time rate parameters, was significantly improved by sildenafil, but slightly worsened by iloprost. CONCLUSIONS: Sildenafil has beneficial effects on cerebral vascular reactivity indicative of an improvement in neurovascular coupling in patients with pulmonary hypertension. These results warrant further investigations of the influence of sildenafil on dynamic vascular function in the brain independent of the underlying disease.

[Therapy of pulmonary arterial hypertension]. / Medikamentöse 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.

Characterisation of post-pneumonectomy lung growth in adult mice.

A model of inducible expansion of the gas exchange area in adult mice would be ideal for the investigation of molecular determinants of airspace regeneration in vivo. Therefore, the post-pneumonectomy (post-PNX) compensatory lung growth in adult C57BL/6 mice was characterised in this study. Mice underwent left-sided PNX. Right lung volume was assessed on days 1, 3, 5, 7, 10 and 21 after PNX, and total DNA and cellular proliferation of the right lung were determined. Lung histology was studied using immunohistochemistry and quantitatively characterised by detailed stereological investigations. Pulmonary function was assessed using a mouse body-plethysmograph. Following PNX, right-lung volume rapidly restored the initial volume of left and right lung. Total DNA increased significantly over 21 days and equalled the total DNA amount of both lungs in the control mice. Septal cell proliferation significantly increased after PNX, and included endothelial cells, epithelial cells, smooth muscle cells and fibroblasts. Stereological investigations of left and right control lungs versus right lungs 21 days after PNX indicated complete restoration of body mass-specific alveolar surface area. Pulmonary function testing showed marked alteration at 3 days and normalisation at 21 days post-PNX. In conclusion, well reproducible reconstitution of alveolar gas-exchange surface based on septal tissue expansion may be provoked by pneumonectomy in adult mice.