Choosing the stimulation rate in patients with intermittent bradycardia and a single lead pacemaker.

In order to assess the prevalence of intermittent bradycardia in a pacemaker population, we retrospectively evaluated the occurrence of intrinsic heart activity in 229 patients with ventricular pacing. Spontaneous heart activity was recorded in 60% of the patients. However, the stimulation rate had been decreased in only 40% of the patients in order to allow for longer periods of intrinsic heart activity.

25 years of implanted intracardiac pacers.

In 1962, a simplified method of transvenously inserting an intracardiac electrode and implanting the whole pacemaker system under local anaesthesia was reported from the Karolinska Hospital in Stockholm. This simplified method has been universally adopted and pacemakers are now probably implanted too freely in many places. In the Stockholm area pacemakers are implanted half as frequently as in the rest of Sweden and as often as in the United Kingdom.

Valsalva-induced variations in the intracardiac signal.

Variations in the intracardiac signal may substantially affect the sensing function of cardiac pacemakers. As the Valsalva maneuver causes a change in heart volume, its effect on the intracardiac signal was studied in seven patients with an adequate escape rhythm who had permanent ventricular pacemakers. During generator replacement, they were asked to perform a standardized Valsalva maneuver.

A comparison between conventional and basket transvenous electrodes.

Three transvenous electrodes, two of a conventional type and one in the shape of a wire basket, were compared. In order to make a valid comparison, the electrodes were all attached to the same kind of lead. The conventional large and small surface electrodes showed no difference in early complication rate.