Pacemaker Dysfunction Research Articles

Effects of radiofrequency catheter ablation on patients with permanent pacemakers.

The objective of this study was to assess the effects of radiofrequency energy application on implanted pacemaker functions. Radiofrequency (RF) catheter ablation may cause pacemaker dysfunction due to electromagnetic interferences. The effects of RF on pacemaker behavior were studied in a series of 38 pacemakers, implanted 18 +/- 26 months prior to a RF procedure using either a right ventricular approach (AV node ablation, n = 35) or a left ventricular approach (left concealed accessory pathway ablation, n = 1; VT ablation, n = 2). The 38 patients (mean age 65 +/- 9 years) included 20 men and 18 women. Before energy applications, the 23 different pacemaker models were programmed to the VVI mode at the lowest available rate. The continuous surface ECG was recorded throughout the procedure. Thorough testing of the devices was performed before and after each RF delivery. Unusual pacemaker responses occurred in 20 of the 38 cases studied (53%). The impact of RF delivery was unpredictable, and variable dysfunctions were observed at different times for a given patient or could vary for a given model. Unusual pacemaker responses included pacemaker inhibition (n = 8), untoggled backup mode (n = 3), electromagnetic interference noise mode (n = 3), temporary RF-induced pacemaker tachycardia (n = 2), erratic behavior (n = 1), oversensing of RF onset and offset (n = 8), and transient loss of ventricular capture, (n = 1). Postablation, most devices automatically toggled back to full functionality. The three devices in the untoggled backup mode had to be reprogrammed to obtain normal operations. At the end of the procedure, pacing thresholds remained unchanged in all but one patient, in whom the increase in ventricular threshold was due to a nicked lead. In conclusion, implanted pacemakers frequently exhibit transient, unpredictable responses to RF energy application. Although all pacemaker functions were restored postablation, some devices had to be reset manually. The anomalies observed during the RF application argue for the simultaneous use of an external pacemaker in pacing-dependent patients.

Intermittent pacemaker dysfunction caused by digital mobile telephones: Barbara Naegeli, Stefan Osswald, Martin Deola, Felix Burkart. Cardiac Unit, Department of Internal Medicine, University Hospital, Basel, Switzerland. J Am Coll Cardiol 1996;27:1471–7

Intermittent pacemaker dysfunction caused by digital mobile telephones: Barbara Naegeli, Stefan Osswald, Martin Deola, Felix Burkart. Cardiac Unit, Department of Internal Medicine, University Hospital, Basel, Switzerland. J Am Coll Cardiol 1996;27:1471–7

Intermittent pacemaker dysfunction caused by digital mobile telephones

Objectives. This study was designed to evaluate possible interactions between digital mobile telephones and implanted pacemakers.Background. Electromagnetic fields may interfere with normal pacemaker function. Development of bipolar sensing leads and modern noise filtering techniques have lessened this problem. However, it remains unclear whether these features also protect from high frequency noise arising from digital cellular phones.Methods. In 39 patients with an implanted pacemaker 14 dual-chamber [DDD], 8 atrial-synchronized ventricular-inhabited [VDD(R)] and 17 ventricular-inhibited [VVI(R)] pacemarkers), four mobile phones with different levels of power output (2 and 8 W) were tested in the standby, dialing and operating mode. During continuous electrocardiographic monitoring, 672 tests were performed in each mode with the phones positioned over the pulse generator, the atrial and the ventricular electrode tip. The tests were carried out at different sensitivity settings and, where possible, in the unipolar and bipolar pacing modes as well.Results. In 7 (18%) of 39 patients, a reproducible interference was induced during 26 (3.9%) of 672 tests with the operating phones in close proximity (<10 cm) to the pacemaker. In 22 dual-chamber (14 DDD, 8 VDD) pacemakers, atrial triggering occurred in 7 (2.8%) of 248 and ventricular inhibition in 5 (2.8%) of 176 tests. In 17 VVI(R) systems, pacemaker inhibition was induced in 14 (5.6%) of 248 tests. Interference was more likely to occur at high power output of the phone and at maximal sensitivity of the pacemakers (maximal vs. nominal sensitivity, 6% vs. 1.8% positive test results, p = 0.009). When the bipolar and unipolar pacing modes were compared in the same patients, ventricular inhibition was induced early in the unipolar mode (12.5% positive test results, p = 0.0003).Conclusions. Digital mobile phones in close proximity to implanted pacemakers may cause intermittent pacemaker dysfunction with inappropriate ventricular tracking and potentially dangerous pacemaker inhibitions.

Pacemaker twist: Twiddler's syndrome

Two clinically asymptomatic cases of cardiac pacemaker twist or Twiddler's syndrome are presented. These examples illustrate that not all cases of pacemaker twist are symptomatic and need intervention. Both patients had unipolar pacemaker systems inserted for second degree heart block and sick sinus syndrome, respectively. The diagnosis of pacemaker twist was made on routine chest radiograph, requested for conditions unrelated to pacemaker dysfunction. No manipulation of pacemakers was documented. The recognition and documentation of radiological signs of pacemaker twist is important as a baseline for follow up especially if symptoms of pacemaker dysfunction arise.

The incidence of pacemaker dysfunction during helicopter air medical transport

A number of recent publications have raised concern regarding in-flight pacemaker dysfunction during air medical transport. Unfortunately the clinical importance of this problem is unknown. The authors' purpose was to examine the incidence of pacemaker use and malfunction during helicopter air medical transport, using an incidence (cohort) study of an air medical service of a tertiary-care teaching hospital. During the study period, April 1, 1987 through December 31, 1991 2,388 patients were air-transported. Cardiac patients constituted 72% of the total population. Pacemakers were used in 44 patients, temporary transvenous pacemakers in 35, permanent transvenouse in five, and transcutaneous pacers in four patients. No rate-responsive pacemakers were transported. No episodes of pacemaker malfunction were observed (95% confidence interval 0 to .002 for the population as a whole). The authors conclude that pacemaker dysfunction during air medical transport is a very rare occurrence, in part due to the infrequent transport of patients requiring these devices.

The Etiology of Syncope in Pacemaker Patients

A total of 46 patients with syncopal episodes after VVI pacemaker implantation were studied. Of these, 92% had one to three syncopal episodes and 8% more than three. All underwent a thorough clinical examination, which included chest X ray, echocardiogram, neurological exam, and the following protocol: 24-hour Holter monitoring, EEG, blood pressure (BP) measurement in three positions, Doppler exam of the carotid vessels, fasting blood glucose, and head-up tilt table test (60 minutes, 60 degrees). Holter monitoring showed exit block in two patients (4.3%) and failed sensing in one (2.1%). In two patients there was unilateral slowing on EEG. Orthostatic hypotension was found in four patients (8.6%), and hypoglycemia in three insulin-dependent diabetics. An occlusive atherosclerotic plaque in the carotid artery was found in three patients (6.5%). Syncope was induced in 17 patients (36.9%) by the tilt table test, after a mean standing time of 47 +/- 11 minutes. The mean resting systolic BP of these patients was 140 +/- 24 mmHg, and fell to a mean level of 56 +/- 8 mmHg (mean systolic BP drop was 79 +/- 8 mmHg). Sixteen of these 17 patients with positive tilt table were being paced at the time of syncope and one had a spontaneous heart rate of 73 beats/min. In 14 cases (30.4%) the cause of syncopal episodes after this extensive workup remained unexplained. These results indicate that pacemaker dysfunction is not a major cause of syncopal episodes in pacemaker patients and that these are most often due to vasovagal syncope. Long-term follow-up is warranted to determine the prognostic significance of various types of syncope in pacemaker patients.

Activity-sensing permanent internal pacemaker dysfunction during helicopter aeromedical transport

This study was designed to establish the frequency, magnitude, and possible etiologies of the dysfunction of activity-sensing internal pacemakers during helicopter aeromedical transport. Two models of Medtronic Activitrax pacemakers were attached externally to healthy adult volunteers. Each volunteer then was loaded into the helicopter and subjected to a flight sequence. Pacemaker firing rates throughout this sequence were recorded. On separate days, Aerospatiale Dauphin and Twinstar helicopters completed a total of 23 flights. Four healthy adult volunteers, two men and two women, participated. These included intra- and inter-flight threshold re-programming and external magnet application. The average preflight pacemaker rate of 65 beats per minute increased to an average in-flight rate of 105 beats per minute, which resolved to preflight rates on shutdown. This pattern was consistently extinguished with external magnet application. The effect of rotor motion and flight vibration on the rate-response of the Activitrax pacemaker is both predictable and easily preventable. Possible guidelines for the safe transport of these patients, using pacemaker reprogramming or external magnet application, are examined.

Cardiac strangulation: Two-dimensional echo recognition of a rare complication of epicardial pacemaker therapy

Permanent epicardial pacemaker therapy is occasionally required in newborn infants for congenital complete heart block and in young infants for surgically acquired heart block. 1,2 In addition to the usual concerns encountered in any age group, such as lead fracture, pacemaker dysfunction, pericardial effusion and infection, 3–5 infants present the additional problem of requiring an adequate length of wire to allow for growth. We report an unusual complication of pacemaker therapy in a newborn: cardiac strangulation.

Utility of ambulatory electrocardiography in detecting pacemaker dysfunction in the early postimplantation period

The value of ambulatory electrocardiography (AECG) in detecting pacemaker dysfunction before hospital discharge was assessed in 100 patients a mean of 1.2 days after pacemaker implantation. The incidence of permanent pacemaker dysfunction detected by AECG in the early postimplantation period, the frequency that pacemaker dysfunction detected by AECG was not detected by telemetric monitoring and the frequency that results of AECG led to pacemaker reprogramming before hospital discharge were determined. AECG detected at least 1 type of pacemaker dysfunction in 35% of patients and routine telemetry identified the abnormality in only 8% (p < 0.001). Pacemaker dysfunction occurred in 42% of patients with dual-chamber devices and 27% of those with single-chamber devices (difference not significant). In the 35 patients who had pacemaker malfunction, a total of 50 instances of pacemaker dysfunction were detected. Failure of atrial capture occurred in 2% of patients, failure of atrial sensing in 9%, failure of atrial output in 1%, failure of ventricular capture in 8%, failure of ventricular sensing in 14%, failure of ventricular output due to myopotential inhibition in 11% and pacemaker-mediated tachycardia in 5%. The results of the AECG led to a clinical intervention in 22 patients (pacemaker reprogramming in 21 patients and lead repositioning in 1 patient) in whom no pacemaker dysfunction was suspected on the basis of telemetry or clinical symptoms. In conclusion, AECG provides additional benefit beyond that of routine telemetry monitoring in identifying pacemaker dysfunction in the early period after implantation.

Comparative Electrophysiological Evaluation of Atrial Activation and Sinoatrial Node Function Following Senning and Mustard Procedures: An Experimental Study

We compared several electrophysiological variables before and after Mustard and Senning procedures in 14 mongrel dogs and made the following three observations. First, after the Senning operation, the atrial activation in the areas of the anterior and middle internodal tracts is undamaged. After the Mustard procedure, however, conduction through the interatrial septum is practically abolished. Both techniques damage the area of the posterior internodal tract. On the whole, there is greater dispersion of atrial epicardial mapping with the Senning operation. Second, several degrees of depression in the sinus node automatism and intraatrial conduction were observed with both techniques. Third, atrioventricular block in various degrees was observed only after the Mustard procedure. The atrioventricular dissociation observed after the Senning operation was dependent on sinus pacemaker dysfunction only. We think that from the electrophysiological point of view, the Senning procedure is a valid alternative for repair of transposition of the great arteries.

Long-term follow-up of young adults following permanent pacemaker placement for complete heart block

Young adults with nonsurgically induced complete heart block (CHB) do not necessarily have a banign prognosis and pacemaker (PM) implantation may be necessary. No one has reported long-term PM follow-up in young adults with CHB. We studied 13 patients aged 15 to 37 years (mean 24 years) at PM implantation. There were nine female and four male patients. All were functional class II or III (NYHA) before PM implantation. Syncope, dizziness, fatigue, shortness of breath, and dyspnea on exertion were the most common symptoms. Cardiac catheterization findings (11 of 13 patients) were normal in five, and additional cardiac anomalies were present in six. His bundle studies (9 of 13 patients) showed absent AH intervals in all patients, with HV intervals not identified in two, 20 to 30 msec in one, and 30 to 50 msec in six patients. Holter monitor recordings (8 of 13 patients) demonstrated CHB in all eight with intermittent second- to third-degree block in two of these patients. Two patients had occasional premature ventricular contractions. Stress exercise tests (9 of 13 patients) demonstrated increased ventricular rate response (although subnormal in some patients); symptoms developed in seven. One patient had ventricular ectopy. All 13 patients were contacted 3 months to 7 years (mean 4 years) after PM implantation. Two patients had died, but the deaths were not related to PM dysfunction. All patients who are currently alive had marked improvement in functional symptomatology and all are currently functional class I. CHB is not a benign condition in young adults and may require PM implantation, which improves symptoms and allows the patient to lead a normal life.

A clinical evaluation of an improved Holter monitoring technique for artificial pacemaker function.

This paper discusses shortcomings of conventional Holter monitoring in paced patients and describes a new technique which permits reliable detection of intermittent pacemaker malfunction and counts pacemaker activity during the recording period. Evaluation of the system of 64 consecutive patients revealed 15 with unsuspected episodic pacemaker dysfunction.

Pacemaker pseudodysfunction with a coronary sinus pacemaker

A permanent transvenous coronary sinus pacemaker functioned effectively for 22 months both as an atrial and ventricular pacemaker. Slow atrial flutter resulted in failure of the pacemaker to capture the myocardium and thus incorrectly suggested pacemaker dysfunction. Transtelephonic evaluation of this phenomenon was particularly difficult and could have resulted in unnecessary replacement of the pacing unit

Inhibition of discharge of an external demand pacemaker by an electric razor

An external demand pacemaker was used in a 54 year old man for atrial pacing in combination with antiarrhythmic drugs to control ventricular irritability after a myocardial infarction. When the patient was shaving with an electric razor, the discharge of the pacemaker was completely inhibited. This phenomenon could be reproduced when the shaver was brought within 6 inches of the pulse generator even at the minimal setting of the demand circuit sensitivity. Individuals caring for patients with pacemakers should be aware that apparently innocuous everyday electric devices may produce an electromagnetic field that can cause complete dysfunction of some demand pacemakers despite “safe” settings of the level of input sensitivity.