Dual chamber pacing: how many patients remain in DDD mode over the long term?

Bipolar, high-voltage, long-duration pulsed radiofrequency ablation of the Gasserian ganglion for the treatment of trigeminal neuralgia in a patient with a cardiac implantable electronic device: illustrative case

BACKGROUND

One of the common methods of treating trigeminal neuralgia (TN) nowadays is radiofrequency therapy. However, it has serious limitations in patients with a cardiac pacemaker because of electromagnetic interference. Therefore, it is crucial to select optimal radiofrequency ablation parameters to make this procedure safe with favorable outcomes for such patients.

OBSERVATIONS

In this study, the authors present a case of a 70-year-old man with a history of cardiac pacemaker dependency and previous microvascular decompression with complaints of severe, constant facial pain. After reprogramming the cardiac implantable electronic device (CIED), the authors performed bipolar, high-voltage, long-duration pulsed radiofrequency therapy (PRFT) of the Gasserian ganglion under electrocardiography and pulse rate control in the pre-, intra-, and postoperative periods. There were no cardiovascular or neurological complications after PRFT. The patient reported relief of pain after the procedure, and at the 9-month follow-up, he was pain-free.

LESSONS

This clinical case demonstrates that the use of bipolar, high-voltage PRFT for TN treatment in patients with a CIED can be safe and effective, provided that the rules and pacemaker instructions are followed. It is necessary to use ablative treatment with caution and to guide the patient in collaboration with a cardiac surgeon and an anesthesiologist resuscitator.

Development of atrial fibrillation in patients with atrioventricular block after atrioventricular synchronized pacing

Many studies have evidenced an increased incidence of AF in patients receiving single chamber ventricular pacing (VVI) when compared with those undergoing an atrial-based system (AAI or DDD). However, the difference in incidence of AF between two atrial-based systems (VDD, DDD) in patients with AV block was still controversial. This study was conducted to compare the development of AF between different modes of pacemakers (VDD and DDD) in patients with symptomatic AV block. A retrospective review was conducted of the detailed records of all consecutive patients who received permanent pacemakers due to symptomatic bradycardia from March 1995 to March 2000. The occurrence of AF was documented when there was presence of AF in the free-run or 12-lead ECG, any ECG strips, or persistent AF on 24-hour Holter ECG during the follow-up. The study included 152 patients (44 women, 108 men; mean age 73). The patients were divided into two groups: VDD (n = 100) and DDD (n = 52). The mean follow-up was 48.9 +/- 22.9 months. The incidence of AF was 7.9%. A higher incidence of AF was noted in the DDD group (15.4%) when compared with the VDD group (4.0%, P = 0.023). The incidence of development of AF in patients with AV block was higher in those receiving DDD cardiac pacing when compared with those who received the VDD system. The authors suggest that VDD pacing may be a better choice than the DDD system for patients with AV block, but without clinical evidence of sinus node dysfunction, and if an atrial lead is required, it should be placed close to the Bachmann's bundle.

Prospective Randomized Study of Mode Switching in a Clinical Trial of Pacemaker Therapy for Sinus Node Dysfunction

INTRODUCTION

Atrial fibrillation (AF) is common in pacemaker patients with sinus node dysfunction (SND) and may result in rapid ventricular pacing (RVP) in the DDDR mode. Mode switching (MS) reduces RVP, but its clinical benefit in patients with SND is unknown.

METHODS AND RESULTS

Two hundred two patients in the Mode Selection Trial (MOST; 2,010-patient, 6-year trial of DDDR vs VVIR pacing in SND) randomized to DDDR pacemakers with atrial high-rate episode (AHRE) storage capabilities were subrandomized to MS ON (N = 96) or MS OFF (N = 106). Cardiovascular symptoms, quality of life (QOL), reprogramming due to RVP, death, stroke, and heart failure hospitalization (HFH) were compared between groups. The treatment groups were similar with regard to AF history (59% MS ON vs 57% MS OFF). AHREs occurred in 49% patients during median follow-up of 2.2 years. Median AHRE duration (in min; MS ON 116 vs MS OFF 58, P = 0.29), frequency AHREs/week (MS ON 3.5 vs MS OFF 6.4, P = 0.23), and time spent in AHRE (min/week) (MS ON 450, MS OFF 268) were similar. Reprogramming due to any RVP during AHREs occurred more in MS OFF vs MS ON (13.2% vs 3.1%, P = 0.011) and marginally more for symptomatic RVP (8.5% vs 2.1%, P = 0.062). Cardiovascular symptoms occurred in 93.6% MS ON vs 90.2% MS OFF (P = 0.38). Median number of symptoms reported per visit was similar (MS ON 1.3 vs MS OFF 1.5, P = 0.62). Median symptom frequency/severity, summed and averaged over visits, was similar (MS ON 4.3 vs MS OFF 4.5, P = 0.74). QOL was not different between groups. Death, stroke, and HFH were not different between groups.

CONCLUSION

MS reduces pacemaker reprogramming due to RVP during AHREs in a small number of patients but does not improve QOL or cardiovascular symptoms overall among patients with SND.

Pacemaker diagnostics: a critical appraisal of current technology

Diagnostic information retrieved from a pacemaker offers the ability to improve patient care. Pacemaker diagnostic data provides information regarding pacemaker function and activity, lead function, arrhythmia occurrence, and data to aid in optimal pacemaker programming. Current pacemakers incorporate greater storage capabilities, more efficient means of storing and presenting data between follow-up visits, and more options for programming diagnostic functions and algorithms. The cardiac rhythm of the paced patient can be evaluated via real-time intracardiac electrograms at interrogation, surface electrocardiograms, ambulatory electrocardiograms, and by pacemaker stored diagnostic function that may include stored intracardiac electrograms. This article focuses on the various methods of obtaining diagnostic information regarding pacemaker activity, pacemaker function, and diagnostic information on cardiac arrhythmias. The current clinical applicability and limitations of these methods and the use of stored diagnostic data in the clinical follow-up and study of patients with pacemakers is discussed.

DDD pacing mode survival in children with a dual-chamber pacemaker

BACKGROUND

The persistence of DDD pacing is well documented in adults, however, in children survival of the DDD pacing mode is less clear.

METHODS

We studied the survival of dual-chamber (DDD) pacing in 36 children aged 1 week to 16 years who underwent implantation of a dual-chamber pacing system between January 1986 and October 1998. The children were divided in the following two groups: 26 had epicardial pacing systems and 10 had endocardial pacing systems.

RESULTS

During long-term follow-up 11 patients lost the DDD pacing mode. The DDD pacing survival rate at 3 months and 1, 2, and 5 years was 80%, 77%, 73%, and 69%, respectively. Age, weight, congenital heart disease, and epicardial pacing leads were not found to be risk factors for loss of DDD pacing mode. However, P-wave values of less than 2.5 mV at implantation of epicardial leads were associated with loss of the DDD pacing mode.

CONCLUSIONS

The majority of children remain in the DDD pacing mode during long-term follow-up. A P-wave value of less than 2.5 mV at implantation of epicardial leads is a risk factor for loss of the DDD pacing mode.

Efficacy of single lead VDD pacing in patients with impaired and normal left ventricular function

Atrial synchronous ventricular pacing seems to be the best pacing mode for patients with advanced AV block and impaired LV function. The long-term follow-up of single lead VDD pacing was studied in 33 patients with impaired LV function and compared to 42 patients with normal LV function. All patients received the same VDD lead and VDDR pacemaker. The lead model with 13-cm AV spacing between the atrial and ventricular electrode was implanted in 89% of the patients. Follow-ups were 1, 3, 6, and 12 months after implantation. The percentage of atrial sensing and the P wave amplitude were determined at each follow-up. Minimal P wave amplitude at implantation was 2.0 +/- 1.4 mV in patients with impaired and 1.7 +/- 0.9 mV with normal LV function (not significant). At the 12-month follow-up, 33 patients with normal and 23 patients with depressed LV function remained paced in the VDD mode. The remaining patients died in five (impaired LV function) and seven cases (normal LV function) or their pacemakers were programmed to the VVI/VVIR pacing mode in four (impaired LV function) and three cases (normal LV function). P wave amplitude did not differ in the two groups (e.g., at month 12: impaired: 1.17 +/- 0.42 mV; normal: 1.09 +/- 0.49 mV). The atrial sensitivity was programmed in most patients to sensitive settings with no differences between the two groups (e.g., at month 12: impaired: 0.13 +/- 0.06 mV; normal: 0.13 +/- 0.05 mV). The diagnostic counters indicated nearly permanent atrial sensing (e.g., at month 12: impaired: 99.3 +/- 2.2%; normal: 99.0 +/- 1.0 mV). In conclusions, single lead VDD pacing restored AV synchronous ventricular pacing in patients with normal and with impaired LV function indicating that it could be an alternative to DDD pacemakers, but not to dual-chamber pacing.

Age dependency of sensing performance and AV synchrony in single lead VDD pacing

Implantation of single lead VDD pacemakers is an established therapeutic option in patients with AV block and normal sinus node function. However, related to occurrence of sinus node disease and atrial undersensing, there is concern whether VDD devices are appropriate in physically active young patients. Two hundred thirty-two consecutive patients with isolated AV block and VDD pacemakers were investigated. This population was subdivided into quartiles of 58 patients according to age at time of inclusion: 26.2-59.4 years (group A), 59.5-70.1 years (group B), 70.2-81.0 years (group C), and 81.1-92.5 years (group D). Follow-up visits included pacemaker telemetry, Holter monitoring, and exercise testing. Patients were visited at 2 and 12 weeks after implantation thereafter followed by 6-month intervals. Mean follow-up period was 35 +/- 14 months. Three months after implantation, atrial sensing threshold was significantly higher in young patients: 1.18 +/- 0.58 mV (group A) versus 0.79 +/- 0.35 mV (group B), 0.68 +/- 0.33 mV (group C), and 0.60 +/- 0.25 mV (group D), P < 0.001 for comparison of group A to all other groups. Atrial undersensing was observed less frequently in young patients: 6.9% (group A) versus 17.2% (group B), 24.1% (group C), and 27.6% (group D), P = 0.025 for intergroup comparisons. Sinus node dysfunction did not occur in group A. Atrial arrhythmias and loss of AV synchronized pacing mode occurred rarely in young patients: 0.6% (0.4%) per year in group A versus 1.3% (1.3%) in group B, 3.9% (3.4%) in group C, and 5.7% (7.4%) per year in group D, P < 0.01 for intergroup comparisons. Our data show good atrial sensing performance, low incidence of sinus node dysfunction, and few atrial arrhythmias in young patients with VDD pacing for AV block. Thus, single lead VDD pacing can be recommended particularly for young patients with AV block.

Importance of ventricular rate after mode switching during low intensity exercise as assessed by clinical symptoms and ventilatory gas exchange

Automatic mode switching from DDD(R) to DDI(R) or VVI(R) pacing modes has improved dual chamber pacing in patients at high risk for supraventricular tachyarrhythmias. However, little is known about the effect of ventricular pacing rate adaptation after mode switching. We conducted a single-blinded, crossover study in 15 patients (58 +/- 21 years) with a DDD pacemaker who had AV block and normal sinus node function to investigate the influence of pacing rate adaptation to intrinsic heart rate during low intensity exercise. Patients performed two tests (A/B) of low intensity treadmill exercise (0.5 W/kg) in randomized order. They initially walked for 6 minutes while paced in DDD mode. The pacing mode was then switched to VVI with a pacing rate of either 70 beats/min (test A) or matched to the intrinsic heart rate (95 +/- 11 beats/min test B). Respiratory gas exchange variables were determined and patients classified the effort before and after mode switching on a Borg scale from 6 to 20. Percentage changes of respiratory gas exchange measurements were significantly larger (O2 consumption: -8.2 +/- 5.0% vs. -0.6 +/- 7.2%; ventilatory equivalent of CO2 exhalation: 5.3 +/- 4.9% vs. 1.5 +/- 4.3%; respiratory exchange ratio: 7.0 +/- 2.2% vs. 3.5 +/- 3.0%; end-tidal CO2: -5.7 +/- 2.9% vs. -1.8 +/- 2.7%; all P < 0.01) and the increase in subjective assessment of the effort tended to be higher (mean increase on Borg scale: 1.6 +/- 1.9 vs. 1.1 +/- 1.8, P = 0.07) after heart rate unadjusted than after adjusted mode switching. Mode switching from DDD to VVI pacing is better tolerated and gas exchange measurements are less influenced if ventricular pacing rate is adjusted to the level of physical activity. Thus, pacing rate adjustment should be considered as part of automatic mode switch algorithms.

Development of sinus node disease in patients with AV block: implications for single lead VDD pacing

OBJECTIVE

To investigate the incidence of sinus node disease after pacemaker implantation for exclusive atrioventricular (AV) block.

DESIGN

441 patients were followed after VDD (n = 219) or DDD pacemaker (n = 222) implantation for AV block over a mean period of 37 months. Sinus node disease and atrial arrhythmias had been excluded by Holter monitoring and treadmill exercise preoperatively in 286 patients (group A). In 155 patients with complete AV block, a sinus rate above 70 beats/min was required for inclusion in the study (group B). Holter monitoring and treadmill exercise were performed two weeks, three months, and every six months after implantation. Sinus bradycardia below 40 beats/min, sinoatrial block, sinus arrest, or subnormal increase of heart rate during treadmill exercise were defined as sinus node dysfunction.

RESULTS

Cumulative incidence of sinus node disease was 0.65% per year without differences between groups. Clinical indicators of sinus node dysfunction were sinus bradycardia below 40 beats/min in six patients (1.4%), intermittent sinoatrial block in two (0.5%), and chronotropic incompetence in five patients (1.1%). Only one of these patients (0.2%) was symptomatic. Cumulative incidence of atrial fibrillation was 2.0% per year, independent of the method used for the assessment of sinus node function and of the implanted device.

CONCLUSIONS

In patients undergoing pacemaker implantation for isolated AV block, sinus node syndrome rarely occurs during follow up. Thus single lead VDD pacing can safely be performed in these patients.

Atrial sensing and AV synchrony in single lead VDD pacemakers: a prospective comparison to DDD devices with bipolar atrial leads

INTRODUCTION

Single lead VDD pacing has offered an alternative to DDD systems in patients with isolated AV block. Up to now, however, the relative performance of these pacemaker systems was not systematically compared.

METHODS AND RESULTS

Three hundred sixty patients who received either a VDD pacemaker (n = 180) or a DDD device (n = 180) with a bipolar atrial lead were investigated prospectively for a mean period of 30 +/- 13 months. Pacemaker function was analyzed by telemetry, Holter monitoring, and exercise ECG. Time of implantation and fluoroscopy was significantly lower with VDD devices (44.3 +/- 5.1 min vs 74.4 +/- 13.5 min and 4.6 +/- 2.5 min vs 10.3 +/- 5.6 min in DDD pacemakers, respectively). Intermittent atrial undersensing occurred in 23.3% of patients with a VDD pacemaker and in 9.4% with DDD devices (NS). The incidence of atrial tachyarrhythmias did not differ between the VDD (6.7%) and the DDD group (6.1%). Sinus node dysfunction developed in 1.9% of patients, but the vast majority (85.7%) of patients were asymptomatic. There was a tendency for a higher rate of operative revisions in the DDD group (6.1% vs 3.3% in VDD pacemakers, P = 0.15). Cumulative maintenance of AV-synchronized pacing mode was 94.9% in patients with VDD pacemakers and 92.1% with DDD devices (NS).

CONCLUSION

With the benefit of a simpler implant procedure, long-term outcome of single lead VDD pacing is equivalent to DDD pacing in patients with AV block and preoperative normal sinus node function.

[Pacemaker therapy in patients with atrial fibrillation]

Pacemaker therapy in patients with atrial fibrillation means the best current pacemaker therapy for patients with bradycardias with the aim to avoid the onset of atrial fibrillation and to establish DDD pacing despite of a history of atrial tachyarrhythmias. The newer application of pacing is the suppression of atrial arrhythmias in patients with medical refractory atrial tachyarrhythmias. Patients with slow ventricular rates and permanent atrial fibrillation should receive a VVI-pacemaker, if the bradycardias causes syncope, dizziness or a decrease of their exercise tolerance. In case of chronotropic incompetence the pacemaker should provide rate responsive pacing. Patients with sick sinus syndrome should receive an atrial (AAI) or dual-chamber (DDD) pacemaker, because patients with these in contrast to VVI-pacemakers develop less often atrial fibrillation and subsequent complications such as atrial thromboembolism. A dual-chamber or VDD-pacemaker--the latter connected to a VDD-single-lead--is indicated in patients with advanced AV-block. Atrial fibrillation occurs in 3 to 6% of the patients with no history of arrythmia and is, if pacemakers have no automatic mode switch, an often reason to program the devices to the VVI-pacing mode. Nowadays, most DDD(R)-pacemakers provide an automatic mode switch: During an atrial tachycardia the pacemaker switches to a VVI/VVIR mode and restores the initial DDD(R)-pacing mode with termination of the arrhythmia. In respect to the newer applications, one approach to prevent atrial tachyarrhythmias is permanent atrial pacing. As lower pacing rates of 80 to 90 ppm are usually needed and many patients hardly tolerate these pacing rates, new algorithms are under clinical investigation. Another approach is the simultaneous depolarization of the right and left atrium. Biatrial pacing is performed with one lead in the high right atrium and another lead in the coronary sinus. Another solution is bifocal atrial pacing with leads placed in the high right atrium and in the coronary sinus ostium. One effect of the new pacing techniques is to shorten interatrial conduction times. Therefore, biatrial pacing has become a therapy to prevent atrial arrhythmias deriving from delayed interatrial conduction times. As atrial reentry circuits seem to be important in atrial fibrillation, multisite atrial pacing is also performed in patients with medical refractory paroxysmal atrial fibrillation. Preliminary results suggest a more effective prevention of atrial fibrillation; nevertheless, these techniques should be still restricted to patients enrolled in clinical studies.

The signal averaged P wave in atrioventricular block--evidence for abnormal atrial conduction?

The incidence of atrial fibrillation in patients with atrioventricular block (AVB) appears increased over that for the unpaced population even if atrioventricular synchrony is maintained by dual chamber pacing. To assess whether atrial fibrillation in these patients might be due to concurrent abnormality in atrial activation we performed signal averaged P wave (SAPW) recordings in 15 patients with dual chamber pacemakers implanted for AVB and compared the results to those from 21 unpaced controls. The median (range) age was 69 (53-89) years for patients and 60 (51-78) years for controls. Eleven patients and 12 controls were male. All patients were pacing in VDD mode at the time of study. SAPW recordings were obtained using our previously reported selective P wave averaging system. We measured P wave duration after high pass filtering at 40 Hz, the rate of change of P wave voltage over time (spatial velocity) and low and high frequency spectral energy after Fourier transformation of the P wave signal. We found increased P wave duration, mean spatial velocity and lower frequency energy in patients with AVB compared to controls [duration, 144 (5) vs. 134 (2) ms, p<0.05; mean spatial velocity, 5.6 (0.4) vs. 4.6 (0.1) mV/s, p<0.05; energy 20-150 Hz, 57.4 (8.2) vs. 36.3 (2.8) muV2.s, p<0.01. All values mean (SEM)]. These results suggest that the increased incidence of atrial fibrillation in patients paced for AVB may be related to intrinsic abnormalities of atrial activation and not solely to the pacing mode. Ensuring sequential atrioventricular pacing in these patients may not completely abolish the increased incidence of atrial fibrillation.

[Selection of the optimal pacemaker - Are age and secondary disease related health conditions significant?]

In pacemaker statistics a dichotomy exists between the theoretically possible and the actually implanted number of physiological pacemakers. Hence, the aim of the study was to investigate the influences of age and non rhythm related health conditions on the selection of the pacemaker system.In 468 pacemaker patients the arguments for mode selection at first implantation were listed prospectively during a period of 3 years and 9 months. Mode selection followed electrocardiographic (recommendations of the German working Group on Cardiac Pacing), clinical (incidence of only intermittent bradycardias, stage of the underlying cardiac or of a second noncardiac disease) and sociomedical (non rhythm related general heath condition) aspects. Regarding the ECG findings physiological pacing was possible in 329 cases. Nevertheless, 57 of them (17.3%) received a VVI(R) system. Analysis of the reasoning leading to this dicision demonstrated that age-related problems and non-rhythm-caused health conditions became superior instead of rhythmologic aspects in 1.0% of all patients (pts) under 70, in 2.7% of all pts between 70 and 79, and in 10.8% of all pts 80 or more years of age.

CONCLUSIONS

Beyond the age of 80 years, in about 11% of the pts who need a pacemaker, non-rhythm-related clinical and sociomedical aspects gain priority over the electrophysiologic defect. Thus, complete coincidence of the theoretically possible and the actually implanted number of physiological pacemakers in this age group cannot be attained. Regarding all factors influencing the selection of the pacemaker system 45 to 55% are more realistic.

Mode switch despite undersensing of atrial fibrillation in DDD pacing

Mode switching algorithms are commonly used to protect the ventricles against high rates induced by atrial tachycardia. In the case of atrial fibrillation (AF), the response of these algorithms depends on the quality of atrial sensing. The Chorum 7234 DDDR pacemaker uses a new mode switching algorithm, based on a statistical analysis of the atrial rhythm. It includes two criteria of diagnosis: "high" if more than 28 of 32 cycles are abnormally accelerated; and "low" if more than 36 of 64 cycles are abnormally accelerated.

METHODS

From a taped database of electrophysiological studies, episodes of AF lasting more than 2 minutes were selected. A tape recorder replayed the atrial signals into an external Chorum device. Each episode was replayed eight times with a programmed atrial sensitivity increasing from 0.4-2.0 mV. For each criterion of diagnosis and each programmed sensitivity, the percentage of atrial sensing, the time to switching, and the mean ventricular rate were measured. Ten episodes of AF from 10 patients (9 men and 1 woman; ages 62 +/- 16 years) were included: 1.95 +/- 0.97 mV and 196 +/- 64 ms. The sensitivity of the algorithm to diagnose atrial tachycardia reached 100%, for an atrial sensitivity set between 0.4 and 1.0 mV. The mean percentages of atrial sensed events were 74% +/- 18% and 46% +/- 9% for the "high" and "low" criteria, respectively. The mean diagnostic times were 28 +/- 26 seconds and 68 +/- 27 seconds, respectively. Sensing of < 23% of AF events resulted in failure to diagnose the arrhythmias by both algorithms. In the event of diagnostic failure, the mean ventricular pacing rate was 79 +/- 9 ppm.

CONCLUSION

Up to an atrial sensitivity of 1 mV, 100% of AF episodes were diagnosed. The Chorum mode switching algorithms are 100% reliable if > 45% of the AF waves are sensed. In the event of switching failure, the ventricle is protected by an average rate remaining below 80 ppm.