Quality assessment of pacemaker implantations in Denmark.

AIMS: Quality assessment of therapeutic procedures is essential to insure a cost-effective health care system. Pacemaker implantation is a common procedure with more than 500,000 implantations world-wide per year, but the general complication rate is not well described. We studied procedure related complications for all implantations performed in an entire nation over a 3-year period. METHODS AND RESULTS: A prospective study of complications related to 99% of the 5648 primary pacemaker implantations performed in the 12 Danish pacemaker centres in 1997-1999 was carried out. Overall 76% of the patients received a physiological pacemaker system and 91% received the optimal pacing mode according to international guidelines. Perioperative complications requiring reoperation were: haematoma 0.3%, atrial lead related 1.9%, ventricular lead related 1.7%. Late complications requiring reoperation were: infection 02%, atrial lead related 13%, ventricular lead related 1.2%. The complication rate decreased over the study period, but overall the complication rate was higher than expected and showed considerable variation between centres. CONCLUSIONS: Our results demonstrate that sensitive data such as complications related to pacemaker implantations can be collected on a national basis. We suggest that a reoperation rate higher than 3% for atrial as well as ventricular pacing electrodes in the individual implanting centre should cause the centre to evaluate carefully the procedure as well as the performance of the individual implanter.

Updated appraisal of pacing lead performance from the Danish Pacemaker Register: the reliability of bipolar pacing leads has improved.

The Danish Pacemaker Register was established in January 1982, and the 12 implanting centers in Denmark report to the Register on a continuous basis by use of the European Pacemaker Patient Identification Card. As of August 1999, the Register contained data on 33,164 bradycardia, endocardial, and epicardial (n = 159) lead implants performed in Denmark on 27,738 generators in 24,180 patients for a total of 17,988 (54.2%) ventricular unipolar, 5,610 (16.9%) ventricular bipolar, 2,056 (6.2%) atrial unipolar, and 7,242 (21.8%) atrial bipolar leads. Lead failure was defined as need for replacement or surgical abandonment of the lead due to pacing or sensing problems with the exception of lead displacement. The 10-year survival rate for unipolar leads was 97.2 +/- 0.4% (+/- 2 SE) as compared to 79.6 +/- 3.2% for bipolar leads (P < 0.001). The Medtronic 4012, the Telectronics 284, and the Siemens (Pacesetter) 1010T, 105T, and 1050T bipolar lead models were poor performing leads that needed careful monitoring and appropriate replacement. Excluding those five poor performing bipolar leads, the models yielded a 10-year survival rate of 94.3 +/- 2.4% for bipolar leads. The 5-year survival for all bipolar leads implanted after January 18, 1993 (this was the date that the last of the five poor performing bipolar lead models were implanted in Denmark) was 98.7 +/- 0.4% compared with 98.9 +/- 0.3% for all unipolar leads implanted after January 18, 1993 and 86.8 +/- 1.6% for all bipolar leads implanted on or before January 18, 1993. These results indicate a significant improvement in bipolar lead reliability.

Appraisal of pacing lead performance from the Danish Pacemaker Register.

The Danish Pacemaker Register was established in January 1982, and the 11 implanting centers in Denmark report to the Register on a continuous basis by use of the European Pacemaker Patient Identification Card proposed by the European Working Group on Cardiac Pacing. As of May 1994, the Register contained data on 18,053 lead implants performed in Denmark, i.e., 1,253 (7%) lead implants before 1982, and all the 16,800 initial lead implants since 1982 on 17,020 generators in 15,366 patients for a total of 12,188 (67.5%) ventricular unipolar, 3,178 (17.6%) ventricular bipolar, 1,316 (7.3%) atrial unipolar, and 1,371 (7.6%) atrial bipolar leads. Preformed J shaped leads were used in 3.5% of the atrial implants and active fixation in < 8%. Lead failure was defined as need for replacement or abandonment of the lead due to pacing or sensing problems with the exception of lead displacement. The 10-year survival rate for unipolar atrial and ventricular leads was 95.8% +/- 2.1% (2 standard errors) and 97.1% +/- 0.6%, respectively, as compared to a 4-year survival rate of 91.5% +/- 4.6% and 91.6% +/- 1.7% for bipolar atrial and ventricular leads, and an 8-year survival rate for bipolar ventricular leads of 75.1% +/- 5.0%. The 5-year survival rate for the bipolar Medtronic model 4012 lead was 85.8% +/- 8.1% and 67.4% +/- 7.3% for the bipolar Siemens model 1010T lead, indicating a poor performance. The Siemens lead models 105T and 1050T seem to be performing like the model 1010T. The 5-year survival rate for the bipolar Telectronics model 284 lead was 88.4% +/- 6.2%. The data from the Danish Pacemaker Register confirm the previous reported good survival of unipolar pacing leads irrespective of the chamber paced, and demonstrate that the bipolar Medtronic 4012 lead, the bipolar Telectronics 284 lead, and especially the bipolar Siemens 1010T, 105T, and 1050T models are unreliable leads that need careful monitoring and appropriate replacement.

[The Danish Pacemaker Registry. A database for quality assurance]. / Dansk Pacemaker Register. En database til kvalitetsvurdering.

The Danish Pacemaker Register was established in 1982 and since then all Danish pacemaker and lead implantations have been registered on a prospective basis by use of the European Pacemaker Patient Identification Card. The Register contains data on 17,002 patients with an implanted pacemaker. In 1994 the implantation rate was 314 per million inhabitants. The ECG indication was atrioventricular conduction disturbances in 46%, sick sinus syndrome in 37% and atrial fibrillation with bradycardia in 13%. Fifteen percent received a single atrial system and 41%, a dual chamber system. In 62% a rate adaptive pacemaker was used. Overall, the international recommendations for choice of pacing mode were met in 64% of the implantations. As the 11 implanting centres in Denmark report to the Register with a few days delay from the intervention, the Register is able to detect any irregularity in pacemaker or lead function within a very short period of time.

The epidemiology of pacemaker implantations in Fyn county, Denmark.

Throughout the last three decades the number of patients with pacemakers has increased. Registers of pacemakers and pacemaker patients have been established to monitor, for example, the battery life expectancy and patient data. We have analyzed the registry for Fyn county, Denmark, which includes data on incidence, prevalence, and mortality rates among patients with pacemakers during the period from 1964 to 1990. The analyses show that the prevalence rate is steadily increasing as a result of a combination of an increasing incidence rate and a stable mortality rate among the pacemaker patients. Based on the development in the first almost 30 years of pacemaker implantations, two trends of the future prevalence of pacemaker patients are projected. Provided constant mortality rates and expected incidence rates of 300 per million person years and 350 per million person years, respectively, the prevalence will reach a plateau of 2.7 per 1,000 persons and 3.1 per 1,000 persons, respectively, within the next 25 years.

[Does alternative medical equipment result in pacemaker dysfunction?]. / Medfører alternativt medicinsk udstyr pacemakerforstyrrelser?

Employment of alternative therapeutic measures is increasing in Denmark. Some of this equipment employs magnetic fields in the therapeutic strategy. This may involve interference with the function of electronic equipment. Electronic interference may, in certain situations, influence pace-maker function. In the worst cases, it may be imagined that the situation may endanger life for persons who are dependent on pace-makers. When a pace-maker is exposed to a magnetic field of a certain strength, the type of pacing is changed to a fixed frequency. Some pace-maker types carry out a built-in test programme when exposed to magnetic influence (vario- or threshold test). The magnetic influence may involve discomfort for the wearer of the pace-maker, but does not endanger life. Investigation of stationary magnetic fields from alternative medical equipment resulted in disturbance of pace-maker function in an isolated case. Pulsating magnetic fields may result in possible induction of electric current which may be wrongly interpreted by the pacemaker. The results of this may be that the pace-maker does not send out pace impulses. As protection from continuous electric noise, pace-makers have a built-in electronic safety circuit (dual-demand). When this is activated, the pace-maker will stimulate with a basic frequency. It is recommended that equipment which employs magnetic fields in treatment should be measured before being employed on pace-maker wearers.

[Placing of implantable devices for electric stimulation]. / Placering af implanterbart elektrostimulationsudstyr.

Various electrical devices are implanted for cardiac-, diaphragma-, pain- and musclestimulation. The stimulator/pacemaker can be implanted in locations, different from that of ordinary cardiac pacemakers. All electric stimulation equipment containing batteries must be removed before cremation on account of the risk of explosion.

Management of spinal cord stimulators in patients with cardiac pacemakers.

We report a case of spinal cord stimulation (neurostimulation) as treatment for angina pectoris pain in a patient with a demand pacemaker. The precautions to avoid inhibition of the demand pacemaker by the neurostimulator are discussed.

Pregnancy and cesarean section in a patient with a rate-responsive pacemaker.

The function of a rate-responsive pacemaker was monitored during pregnancy and cesarean section in a woman with complete atrioventricular block. The observations during pregnancy were compared to similar observations obtained in a pregnant normal woman of comparable age, height and weight, and in 12 normal women during elective cesarean section. During pregnancy, the heart rate increased in the normal woman, whereas the pacing rate in the woman with the implanted pacemaker was unchanged. Fetal movement caused an increase in pacing rate in the 37th week of gestation, whereas the heart rate in the normal woman did not respond. During cesarean section the pacing rate was generally within the mean +/- 1 SD for normal women.

Superiority of multiprogrammable to nonprogrammable VVI pacing: a comparative study with special reference to management of pacing system malfunctions.

Analysis of pacing system malfunctions was performed in 374 patients at initial implantation or at pulse generator and lead replacement during a period of 55 months. A total of 150 nonprogrammable pacemakers were implanted in 148 patients, while 236 multiprogrammable pacemakers were implanted in 226 patients. The purpose of the analysis was to investigate the occurrence and management of malfunction unrelated to pacemaker/lead failure or lead dislodgement. The nonprogrammable group was followed for 3-53 months (median, 36). Malfunction occurred in 18 patients (12.0%): muscle stimulation in 14; exit block in three; sensing problem in one. Surgical correction was necessary in 14 of 18 cases. The multiprogrammable group was followed for 3-52 months (median, 12). Malfunction occurred in 30 cases (12.7%): muscle stimulation in 22; threshold increase in seven; sensing problem in one. Only seven of these patients required surgical correction as 23 cases were successfully managed by reprogramming alone. Malfunctions occurred during a period of several days to 36 months (median, 2.3 months). The difference in rate of secondary surgical intervention was significant (p less than 0.01). Measurements during reoperation in the nonprogrammable group showed that at least 40% of late malfunctions would have been correctable by reprogramming alone. Thus, multiprogrammability is of significant value for noninvasive correction of malfunctions unrelated to pacemaker and lead failures, predominantly muscle stimulation and threshold elevation.

Effect of prostaglandin E2 and F2alpha on the systemic and pulmonary circulation in pregnant anesthetized women.

The hemodynamic effect of prostaglandin F2 alpha (PGF2 alpha) and of prostaglandin E2 (PGE2) was studied in 12 healthy volunteers admitted for suction abortion at 10--12 weeks of gestation. They were anesthesized using natrium thiomebumal, pethidine and pancuronium bromide. PGF 2 alpha was given as an intravenous infusion of 100 micrograms/min, the dose being increased by 100 micrograms every 10 min to a maximum of 300 micrograms/min. PGE2 was administered with 5 micrograms/min, the dose being increased by 5 micrograms every 10 min to a maximum of 15 micrograms/min. During infusion of 300 micrograms PGF2 alpha a significant increase iun cardiac output and femoral arterial pressure of 40% and 25% respectively was measured together with an increase in the pulmonary arterial pressure (125%). Pulmonary vascular resistance was doubled, with a concomitant decrease in systemic resistance (11%). These changes were followed by a significant decrease in pH and PaO2, whereas an increase in PaCO2 was found. During infusion of PGE2 a significant, 36% increase in cardiac output was measured during infusion of 15 micrograms/min PGE2, together with a decrease in systemic blood pressure (31%) and resistance (33%). Heart rate rose significantly, while stroke volume showed only a small increase, and pulmonary pressure was unchanged. These changes were followed by an increase in PaO2. PGF2 alpha seems to have a positive inotropic effect on the heart, whereas its response to PGE2 seems to be a result of the peripheral vasodilatation. The slight decrease in systemic blood pressure without change in pulmonary hemodynamics makes PGE2 suitable for induction in patients with cardiopulmonary diseases.

The closed co-axial analgesia system.

A twin-tube system for nitrous oxide analgesia in dental surgeries is described. The system is a non-polluting modification of the Mapleson A system, employing the principle of co-axial tubing introduced by Bain & Spoerel (1972). Active, continuous and calibrated gas removal takes place via the co-axial tubing by means of an ejector flowmeter. Investigation of the dynamic pressure excursions occurring at the nose-piece are fully compatible with normal breathing. Gas contamination of the dental environment can be reduced by at least 90%. The system described is safe and easy to handle. It is made of light-weight material and is adaptable to the equipment available. No rebreathing takes place when using a fresh gas inflow of 150 ml/kg body weight/min.

Measurements of cardiac stroke volume in various body positions in pregnancy and during Caesarean section: a comparison between thermodilution and impedance cardiography.

A total of 220 simultaneous pairs of measurements of cardiac stroke volume were made in twelve women before and during Caesarean section in order to compare impedance cardiography with the thermodilution method. A significantly higher coefficient of correlation was found before (r = 0.77) than during anaesthesia (r = 0.55). Further, there was a significant difference in the slope of the regression lines: before anaesthesia the slope was 1.07 and during anaesthesia with thiopentone, nitrous oxide, oxygen and suxamethonium it was 0.45. Significant changes in the intercept on the Y-axis were found before (-13.9 ml) and during anaesthesia (33.4 ml). When the uterus was displaced upwards and to the left from the 15 degrees tilt position the stroke volume and the cardiac output were increased when measured by both methods to nearly the same values as in the left lateral position. It is concluded that the impedance method is reliable for measuring cardiac stroke volume in late pregnancy under physiological conditions in the conscious patient, but that it cannot replace the thermodilution method in pharmacological studies.

Haemodynamic effects of oxytocin (syntocinon) and methyl ergometrine (methergin) on the systemic and pulmonary circulations of pregnant anaesthetized women.

The haemodynamic effects of oxytocin (Syntocinon) and methyl ergometrin (Methergin) were studied in 9 healthy females in the first trimester of pregnancy. The patients were anaesthetized with sodium thiomebumal, pethidine and pancuronium bromide and ventilated on a Manley respirator. 10 i.u. oxytocin given as an i.v. bolus brought about a fall in femoral arterial pressure of 40%, systemic resistance 59% and pulmonary resistance 44% 30 sec after injection. However, the heart rate increased 31% and stroke volume 17%, so that the cardiac output increased by 54%. The pulmonary arterial pressure and wedge pressure were increased by 33% and 35%, respectively 150 sec after injection. No changes were seen in the haemodynamic parameters during infusion of 80 mU oxytocin for 10 min. 0.2 mg Methergin brought about an increase in the femoral arterial pressure of 11%, pulmonary arterial pressure 27% and wedge pressure 31%, with no changes in the other measured parameters. The use of oxytocic drugs in patients with compromised circulation is discussed.