[Clinical value of the refractory period behavior of the atrioventricular transconduction]

Issuing from the estimation of the maximum 1 : 1-transconduction in rapid stimulation of the atrium (so-called maximum isorhythmia) as a suitable parameter for the refractory behaviour of the atrio-ventricular transconduction the estimation of the refractory periods of the atrio-ventricular transconduction by means of programmed stimulation of the atrium is discussed and particularly the dependence on frequency of all refractory periods of the atrioventricular transconduction is shown. It is emphasized the peculiarity of the effective refractory period of the atrioventricular node to grow longer with increasing frequency of stimulation. It renders the atrioventricular node to the frequency limiting segment of the atrioventricular transconduction, to the so-called "gate" of the atrioventricular transconduction. Apart from the prolongation of the individual refractory periods recognizable by the maximum isohythmia the establishment of a deviating behaviour of the atrioventricular transconduction which depends on frequency is of clinical importance. This is shown as an example for sinus bradycardia, sinus tachycardia and for investigations of medicaments in general (here for cordanum and obsidan) as well as in therapy studies in the individual patient (here for alupent).