[Application of therapy with atrial controlled ventricular pacemakers with shortened AV delay time].

For the reduction of the functional obstruction of the left-ventricular outflow in hypertrophic obstructive cardiomyopathy since 1978 in selected cases conventional VAT cardiac pacemakers with shortened AV retardation time have been implanted. On the basis of 4 casuistics the insufficient adaptation of these systems to unexpectedly appearing disturbances of the cardiac rhythm is demonstrated. Thus already extreme sinus bradycardias lead to parasystole by the unchangeably given asynchronous basic frequency of the pacemakers. Furthermore, all tachycardiac supraventricular arrhythmias and retrograde atrium activations evoke haemodynamically unfavourable and partly even threatening ventricular tachycardies caused by the pacemakers. Control ECG made under these conditions are frequently inexactly interpreted by the continuing intact natural AV conduction and technical defects of the pacemakers are assumed. The individual diagnostic steps necessary for the assessment of the function of the devices and the inevitable immediate therapeutic measures are, therefore, explained. Finally the demands to more modern differentiated physiological pacemaker systems are derived which should be used in patients with hypertrophic obstructive cardiomyopathy.