Therapy of Pulmonary Arterial Hypertension (PAH) - Treatment With Sildenafil in Eisenmenger Patients

Pulmonary Arterial Hypertension (PAH)

Hypertension, Eisenmenger

Eisenmenger's syndrome presents as a severe clinical picture of polymorbidity that constitutes a great burden at the individual as well as the familial and social level. The combination of critically increased pulmonary vascular resistance, progressive pressure load of the right ventricle and disturbance of pulmonary gas exchange result in long-term polymorbidity. The objective of this study is to provide evidence of improvement of patients exercise tolerance as well as general conditions by treatment with oral sildenafil as a specific pulmonary vasodilator.

Eisenmenger's syndrome presents as a severe clinical picture of polymorbidity that constitutes a great burden at the individual as well as the familial and social level. The combination of critically increased pulmonary vascular resistance, progressive pressure load of the right ventricle and disturbance of pulmonary gas exchange result in long-term polymorbidity. While the patient's ability to care for him-/ herself gets lost over time, the financial burden due to the need for medical consultations and hospital stays increases. This is distressing to both the patient and the family. Usually, death results from cardiac decompensation in the presence of gradually increasing pulmonary vascular resistance and hypoxic lesion of organs including the myocardium (Hopkins, AJC 2002). With a better understanding of the pathophysiology underlying pulmonary hypertension, novel therapeutic approaches have been developed during the past few years. These include a) inhibition of the NO-cGMP-degrading type 5 phosphodiesterase (PDE-5) and b) antagonising the endothelin system (Krum, Curr Opin Investig Drugs 2003). The goal is a dilatation of the abnormally constricted pulmonary arterial vessels by relaxation of the vascular smooth muscle cells with a reversal of pulmonary vascular remodelling (Ghofrani, Pneumologie 2002). Specific drugs affecting pulmonary vascular resistance have been studied. Intravenous prostacyclin has major disadvantages: high cost, tachyphylaxis, risk of infection and rebound hypertension upon discontinuation. Inhalative pulmonary vasodilators, in particular iloprost, may be effective in primary pulmonary hypertension (Olschewski, Ann Int Med 1996; Hoeper, Pneumologie 2001), but administration is time-consuming, and due to its mode of application its effects are intermittent, lasting only about 75 minutes (Hoeper, JACC 2000). Considering this, oral treatments appear preferable, because of easy administration and, hence, better patient compliance. Sildenafil (Revatio®) an inhibitor of the phosphodiesterase 5 (PDE-5) was used in many individual cases (Abrams, Schulze-Neick et al, Heart 2000), some acute studies and two long-term studies in humans to reduce the pulmonary vessel resistance. Significant effects on reduction of the pulmonary vessel resistance were demonstrated for the combination with an inhalational prostanoid (Ghofrani et al, Ann Int Med 2002).Good long-term tolerability and effectiveness over a period of two year were demonstrated by this working group. The objective of this study is to provide evidence of improvement of patients exercise tolerance as well as general conditions by treatment with oral sildenafil as a specific pulmonary vasodilator. The data obtained are supposed to contribute to the development of guidelines for the treatment of Pulmonary Arterial Hypertension (PAH)caused by congenital heart defects. The hypotheses are: 1. Sildenafil heales specific pulmonary vascular damage, which occurs by hypercirculation as quick-acting inhibiting vasoconstriction. 2. Through this there will be a reduction of pulmonary vessel resistance and a normalization of pulmonary reagibility in patients with Eisenmenger syndrome. 3. Pulmonary blood circulation and so systemic arterial oxygen delivery will increase. 4. The patient benefits from this by improving his exercise tolerance as well as general and clinical condition. These hypotheses will be tested by comparing findings of the following examinations before, during and after the 52 or 78-week treatment with sildenafil: clinical examination, Electrocardiogram (ECG), echocardiography, ergospirometry, Magnetic Resonance Imaging (MRI), cardiac catheterization with pulmonary artery manometry, and laboratory tests.

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