Effektivität von positiv inotropen Substanzen am Vorhofsmyokard von Patienten mit chronischem Vorhofflimmern
Background: Immediately after cardioversion of atrial fibrillation (AF) to sinus rhythm (SR) the atrial contractility is impaired. And especially the transience of the atrial contractile dysfunction may play a pivotal role in a postfibrillatory positiv inotropic intervention. Hence we analysed the effect of some positive inotropic agents on the atrial myocardium of patients with chronic atrial fibrillation in vitro. Methods: Biopsies of the right human auricle of the human heart were taken from patients undergoing open mitral valve surgery. 47 patients were in stable SR, 43 patients in chronic AF. From these, bundles of muscle fibres were prepared under microscopic control and stimulated with square pulses at standard conditions (1 Hz, 37°C). Force of contractions (mN/ mm2) before and after the agent specific incubation period were used to characterize the positive inotropy in both groups. In particular, the following agents were analyzed: Ca2+ -Sensitizer (EMD), Na+/ Ka+ -ATPase -Inhibitor (DHO), Na+ -Channel-Modulator (BDF), ß-receptor-agonist (Isoproterenol, Iso), and Calcium (Ca2+) as a reference positive inotropic ion. Conclusions: 1) Although the baseline force of contraction is reduced by nearly 75% in patients with chronic atrial fibrillation, Ca2+ could reveal a strong positive inotropic effect in the AF group. Deductively, the contractile reserve of patients with chronic atrial fibrillation is preserved. 2) Both DHO and Iso were not able to increase the force of contraction in patients with chronic atrial fibrillation compared to SR patients. 3) Ca2+ -sensitizer (EMD) and Na+ -channel-modulator (BDF) were able to enhance the force of contraction in both groups significantly implying an important role as future therapeutic alternatives.
info:eu-repo/classification/ddc/610, Vorhofflimmern, Medizin, Atrial fibrillation
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