[Clinical classification and initial diagnosis of pulmonary hypertension: recommendations of the Cologne Consensus Conference 2016]

The 2015 European Guidelines on Diagnosis and Treatment of Pulmonary Hypertension are also valid for Germany. The guidelines contain detailed information about the clinical classification and diagnosis of pulmonary hypertension, and furthermore provide novel recommendations for risk stratification and follow-up assessments. 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 2016, 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 clinical classification and initial diagnosis of PH. This article summarizes the results and recommendations of this working group.

[Exercise testing in respiratory medicine]

This document replaces the DGP recommendations published in 1998. Based on recent studies and a consensus conference, the indications, choice and performance of the adequate exercise testing method in its necessary technical and staffing setting are discussed. Detailed recommendations are provided: for arterial blood gas analysis and right heart catherterization during exercise, 6-minute walk test, spiroergometry, and stress echocardiography. The correct use of different exercise tests is discussed for specific situations in respiratory medicine: exercise induced asthma, monitoring of physical training or therapeutical interventions, preoperative risk stratification, and evaluation in occupational medicine.

Burden of pulmonary arterial hypertension in Germany

This study aimed to describe health care provision, resource consumption and related costs, as well as treatment patterns and quality of life in adult patients with pulmonary arterial hypertension (PAH) in Germany. Data for this retrospective and prospective cost-of-illness-study were derived from hospitals, general practitioners and patients. Costs were evaluated from the perspective of third party payer and patient. Quality of life data were collected by using three validated instruments. A total of 167 patients were enrolled at 10 hospitals. Time period from first occurrence of symptoms to confirmed diagnosis of PAH was 2.3 years on average. Mean number of GP visits was 1.5 per patient per month, and within 15 months, inpatient stays were reported for 50% of patients. The ratio of combination therapy to single-drug therapy for endothelin receptor antagonists, phosphodiesterase-5-inhibitor and prostacyclin analogues increased significantly during 15 months. Treatment costs were, on average, euro47,400 per patient per year, arising mainly from drugs. Compared to the general population, quality of life of PAH patients was considerably impaired. This is the first study which evaluated aspects of the medical and economic consequences of PAH based on a large cohort of PAH patients in Germany.

[Specific drugs for the treatment of pulmonary arterial hypertension - current status]

For some years drugs of several different classes have been available in Germany for the treatment of pulmonary arterial hypertension (PHT): prostanoids, endothelin-receptor antagonists and phosphodiesterase inhibitors. To-date all relevant studies have consistently shown improvement in the 6-minute walking test (Iloprost, Treprostinil, Bosentan, Sitaxentan, Ambrisentan, Sildenafil). Results have not been consistent when the end-point has been an improvement in New York Heart Association (NYHA) class III or in the time to clinical worsening. Despite the good safety data for all drugs approved in Germany in the treatment of PHT, there are some clinically relevant interactions and significant contraindications. The availability of several options demands a detailed knowledge of studies to optimize safety and success in the treatment of PHT. Placebo-control mortality studies are not available for ethical reasons for those drugs that have been approved in Germany. But cohort analyses using historical survival rates have demonstrated a impressive improvement in survival of patients with PHT. Although there has been great progress in the treatment of PHT, a cure of this grave disease is not yet possible.

Safety and tolerability of bosentan in idiopathic pulmonary fibrosis: an open label study

Idiopathic pulmonary fibrosis (IPF) is a fatal disease for which no effective treatment exists. In the present study, 12 IPF patients underwent analysis of gas exchange properties using the multiple inert gas elimination technique on day 1 before and after the administration of 125 mg bosentan, a dual endothelin antagonist. Following this, patients received chronic administration for 12 weeks (62.5 mg b.i.d. in week 1, 125 mg b.i.d. thereafter). The primary objective was to determine the effect of bosentan on gas exchange (day 1) and on oxygen saturation and minute ventilation (week 2). With one exception, where redistribution of total pulmonary blood flow from normal ventilation/perfusion (V'/Q') areas (93% before, 72% after bosentan) to low V'/Q' areas (0% before, 22.2% after) was encountered, no patient showed any change in gas exchange (mean+/-SD shunt flow (% of cardiac output) 8.5+/-3.4% before, 6.1+/-2.3% after bosentan; day 1) or oxygen saturation and minute ventilation (week 2). Similarly, none of the secondary parameters was significantly changed either at week 2 or at the end of the study period (week 12). Five patients developed respiratory infections and two died because of pneumonia; this was judged as being unrelated to bosentan intake. In conclusion, bosentan administration does not seem to induce clinically relevant gas exchange abnormalities in idiopathic pulmonary fibrosis patients.

Successful treatment of portopulmonary hypertension with bosentan: case report

Pulmonary arterial hypertension (PAH) is found in 2-20% of cirrhosis patients who have portal hypertension (portopulmonary hypertension, PPHT). Endothelin (ET), a potent vasoconstrictor, is likely to play a role in the pathogenesis of portal hypertension. We describe the long-term successful use of the dual ET(A)/ET(B) receptor antagonist bosentan in a 43-year-old male with alcohol-related cirrhosis (Child-Pugh A), right ventricular enlargement and dysfunction, respectively, and moderate PAH. Elevated pulmonary arterial pressure was substantially reduced and exercise capacity increased. Improvement was maintained over 2 years, and bosentan treatment continues in this patient. Our report is in line with a series of current reports in PPHT that support the use of bosentan in this subset of PAH patients.

[A role for combination therapy in pulmonary arterial hypertension]

For patients with pulmonary arterial hypertension (PAH) two first line therapies - iloprost inhalation (Ventavis) and bosentan (Tracleer) -- are available in Germany. A third substance, sildenafil, is already approved in the US and will be approved for this indication in the European Union soon. Patients with PAH can be stabilized or improved with a specific mono-therapy for a limited period of time only. Therefore, the question arises when and how to initiate treatment escalation. The available data from controlled clinical trials are insufficient to give a definite answer to these questions. Moreover, it is still unclear which combination of the above mentioned substances may be superior in the treatment of PAH. On the other hand, combination therapy is already reality in clinical practice. Based on this background experts from specialized centers dealing with PAH discussed the scientific basis of the role of combination therapy in PAH patients during a workshop held on April 22/23. 2005 in Wiesbaden. The goal of this workshop was to formulate a common position with regard to combination therapy of PAH on the basis of the available scientific data and clinical experience.

Alteration of pressure-volume characteristics due to different types of edema induction in isolated rabbit lungs

In a model of isolated, ventilated and perfused rabbit lungs the influence of a fixed amount of edema (standardized at 7 g weight gain/kg body weight) on the pressure-volume characteristics of the isolated lungs was investigated. Periodical stimulation with A 23187 or A 23187 plus indomethacin or A 23187 plus indomethacin plus glutathione evokes an increase in vascular permeability with subsequent severe alterations of the pressure-volume characteristics, reflecting a disturbance in the alveolar surfactant system, which is more extensive the more rapidly the edema develops. The alterations caused this way are markedly more severe than those caused by the same amount of weight gain due to mechanically increased capillary filtration pressure.

Influence of tocopherol, its chromane compound, phytyl chains and superoxide dismutase on increased vascular resistance and permeability due to arachidonate metabolism in isolated rabbit lung

In the model of isolated, ventilated rabbit lungs, perfused with isoionic and isooncotic fluid, the addition of arachidonic acid to the perfusion fluid or the liberation of arachidonic acid by the Ca-ionophore A 23187 result in an increase in pulmonary vascular resistance and permeability. The former can be ascribed to cyclooxygenase products, the latter to lipoxygenase products of arachidonic acid. The effect of alpha-tocopherol, its chromane compound, alpha-tocopherolquinone, phytol, 2-methyl-1,4-naphthoquinone, 2-methyl-3-phytyl-1,4-naphthoquinone and of superoxide dismutase (SOD) on the increase in pulmonary vascular resistance and permeability was investigated. A membrane effect of the phytyl side chain and an antioxidative effect of the chromane compound can be distinguished: phytol increase the arachidonate-induced rise of pulmonary vascular resistance and permeability, whereas the chromane compound decreases both to a large degree. Methyl-phytyl-naphthoquinone and methyl-naphthoquinone gave equivalent results. SOD decreases the enhanced vascular resistance and the vascular leakage. The possibility of antioxidative therapy in acute pulmonary lesions with vascular leakage and increased vascular resistance is discussed.

Increased pulmonary vascular resistance and permeability due to arachidonate metabolism in isolated rabbit lungs

Liberation and metabolism of arachidonic acid may be the common final pathway of different stimuli on the pulmonary vascular bed. In a model of isolated, ventilated rabbit lungs, perfused with Krebs Henseleit albumin buffer in a recirculating system, changes of pulmonary vascular resistance and of vascular permeability are monitored continuously. The addition of free arachidonic acid or of the Ca-ionophore A 23187 to the perfusion fluid consistently evokes a biphasic increase in vascular resistance as well as an initially reversible increase in vascular permeability, followed by pulmonary edema. Both phases of increased vascular resistance are completely suppressed by inhibition of the cyclooxygenase, decreased to a large degree by inhibitors of thromboxane synthetase, and markedly augmented by short preincubation of arachidonic acid with ram seminal vesicular microsomes and by sulfhydryl reagents. The increased pulmonary vascular permeability is augmented by inhibition of cyclooxygenase and reduced by simultaneous lipoxygenase inhibition. Antagonists of histamine, serotonin and sympathic or parasympathic activity do not have any influence. PG F2alpha., TxB2, PG E2 and PG I2 alter the pulmonary vascular resistance, but do not increase vascular permeability. In conclusion, increased availability of free arachidonic acid evokes a rise in pulmonary vascular resistance, which can be ascribed to cyclooxygenase products, especially to thromboxane, and causes a rise in vascular permeability which can be ascribed to lipoxygenase products. The findings may be related to acute pulmonary lesions with increase in vascular resistance and with vascular leakage.

[Increase of pulmonary vascular resistance and permeability due to the metabolism of free arachidonic acid (author's transl)]

Release and metabolism of arachidonic acid are supposed to form the common final pathway of different stimuli on the pulmonary vascular endothelium. In a model of isolated, ventilated and perfused rabbit lungs we investigated the influence of increased availability of free arachidonic acid on pulmonary vascular resistance and permeability. Addition of arachidonic acid to the perfusion fluid or release of arachidonic acid by Ca-ionophore A 23187 regularly produces a characteristic biphasic increase of the pulmonary vascular resistance as well as a continuous increase in permeability, followed by pulmonary edema. Inhibition of cyclooxygenase by indomethacin prevents the augmentation of vascular resistance, the increase of vascular permeability however is enhanced. thus the raise in pulmonary vascular resistance can be ascribed to cyclooxygenase products, the increased pulmonary vascular permeability to lipoxygenase products of arachidonic acid.

[The antioxidative chromane structure of alpha-tocopherol protects against the consequences of arachidonic acid release in the pulmonary vascular bed (author's transl)]

In the model of isolated, ventilated and perfused rabbit lungs release of arachidonic acid results in an increase of pulmonary vascular resistance and permeability. The former can be ascribed to cyclooxygenase products, the latter to lipoxygenase products of arachidonic acid. The effect of alpha-tocopherol on the increase of pulmonary vascular resistance and permeability either after the addition of arachidonic acid to the perfusion fluid or after stimulation of arachidonic acid liberation by Ca-ionophore A 23187 was investigated. It is possible to distinguish a membrane effect of the phytol side chain of alpha-tocopherol and an antioxidative effect of its chromane structure: Phytol augments the increase of pulmonary vascular resistance and permeability, whereas the chromane-structure decreases both to a large degree. The possibility of antioxidative therapy in disturbances of pulmonary vascular permeability is discussed.