[Cardiology 1995].

Rapid progress in the field of cardiology calls for an almost continuous update on latest developments. In particular, this is the case with respect to indications for diagnostic and therapeutic interventions. The present contribution deals with some topics in this area.

[Indications and new developments in pacemaker therapy].

In the course of the past 25 years the indication for pacemaker implantation has changed from AV-block to the sick sinus syndrome in about 40% of patients. In the same period pacemaker technology has developed considerably and today there are, in addition to the ventricular inhibited pacemaker, two-chamber systems (essentially DDD pacemakers) and pacemakers with an increasing pulse rate during physical effort. The new nomenclature, mode of action and hemodynamic implications of the various systems are explained, and recommendations for implantation are given.

Hemodynamic effects of atrial synchronization in acute and long-term ventricular pacing.

The acute and long-term hemodynamic benefit from atrial synchronization in ventricular (VAT) pacing has been investigated at rest and during exercise in 10 patients undergoing pacemaker implantation for complete A-V block. The results were compared to conventional (VOO) ventricular stimulation at rates of 70 BPM and 96 BPM. Cardiac index (CI) in VAT-pacing increased at rest by 8% and during exercise by 15% more than with VOO pacing (p less than 0.

[Surgical treatment of heart rhythm disorders].

Six patients underwent cardiac surgery for refractory tachyarrhythmias. Four had Wolff-Parkinson-White syndrome and 2 ventricular tachycardias after myocardial infarction. The results of preoperative electrophysiologic studies corresponded in 5 cases to intraoperative findings of epicardial and pace-mapping.

[Technic and long term results of pacemaker treatment with atrial electrodes].

A new implantation technique in the upper lateral part of the right atrium has reduced the complication rate of atrial electrodes to less than 4% at 11 months' follow-up. P-wave amplitude and acute and chronic threshold are in the order of conventional ventricular electrodes. In 10 of 56 patients with atrial-triggered ventricular pacemakers the cardiac output at rest and during exercise was found to be respectively 8% and 17% higher than with fixed-rate ventricular pacing.

[Stimulation rate of lithium powered pacemakers in the event of battery depletion].

Between 1976 and 1977, 347 lithium powered pacemakers with capacity below 1.8 Ah have been implanted at Zürich University Hospital. 25 (7%) had to be explanted after an average of 37.

[First clinical experiences with the new intracardial electrode "Helifix"].

A new pervenous non-traumatic screw-in electrode has been developed and tested in 61 patients. Dislocation of this electrode occurred in 2 instances (3.3%) and an increase in threshold (exit-block) in 3 cases (5%) necessitated repositioning of the electrode.

[2 years of clinical experiences with lithium pacemakers].

Between January 1974 and December 1976, 470 mercury-cell pacemakers and 353 lithium-cell pacemakers were implanted at Surgical Clinic A of the University Hospital of Zurich. Within the first 24 months 15.5% of the mercury-cell pacemakers had to be exchanged because of premature battery depletion and 1.

[Various blood-foreign body reactions in the heart-lung machine in heart valve replacement and aortocoronary bypass operations].

Blood-foreign material interaction in the pump oxygenator was studied by means of scanning electron microscopy in 3 patients undergoing heart valve replacement (HVR) and 3 patients undergoing coronary bypass operation (CBO). While polyvinyl tubes show an average deposit of 60 thrombi/mm2 with 20--40 microns in size in CBO, bloodgas interface during HVR causes increasing thrombotic deposits (375 Mcthr/nm2, 25--50 microns in size). Distal to the pump the volume of particles may rise up 250 micrometer in HVR and up to 80 micrometer in CBO.

[Animal experiments with a new intracardial pacemaker electrode].

In order to reduce the rate of dislocation of intracardiac pacemaker electrodes, a new electrode was developed. The tip of this new electrode is helical and can be fixed between the trabecles of the right ventricle by clockwise rotation. Since the tip of this new electrode has no sharp hooks the myocard cannot be damaged by fixation.

[Evaluation of the interaction between blood and foreign material in the pump oxygenator during open-heart surgery in infants by scanning electron microscopy (author's transl)].

Scanning electron microscopy was used to elucidate the interaction between blood and foreign material in the pump oxygenator during open-heart surgery in 7 infants. The loss of platelets upstream of the blood pump is caused by thrombogenicity. The pump itself causes massive destruction of platelets and red blood cells; thromboembolie up to 100 mu and foreign body particles up to 200 mu are being detached from the wall of the tubing to a large extent.