Single Lead VDD Pacing System Research Articles

Long-Term Follow-Up of Single-Lead VDD Pacing System

Introduction: Single-lead VDD system is an alternative mode of cardiac pacing in patients with atrioventricular (AV) block and preserved sinus node function (SN). The aim of this study was to find the predictors of atrial undersensing in long-term VDD-pacing systems. Methods: Ninety-three patients (80.5±9.6-year-old) with normal SN who received single-lead VDD system and 61 patients (78±11-year-old) with normal SN who received dual-lead DDD system were enrolled. Before the pacemaker implantation, we evaluated 13 parameters (age, gender, type of AV block, hypertension, diabetes, heart failure, ischemic heart disease, atrial fibrillation, chronic renal failure, antiarrhythmic agents, digitalis, calcium channel blocker and atrial amplitude of P wave at implantation). We followed up the patients at our outpatient clinic. Results: In VDD group, Mean follow-up duration was 75±41 months (24–173). Atrial undersensing was detected in 17 patients. According to a Kaplan-Meier analysis, heart failure (P=0.0009), P wave 82 years (P=0.0393) were significant predictor of atrial undersensing. A Cox regression analysis showed that the heart failure was an independent predictor (hazard ratio, 4.525; 95% confidence interval, 1.437–14.286, P=0.0032). Re-operation was required in 3 patients. Conclusion: These results indicate that VDD mode is not preferable in the AV block patient who has a history of heart failure even if the SN and atrial amplitude are preserved.

Single-pass lead VDD pacing system in children and adolescents: report of twenty-four patients

The dual-chamber pacing systems allow for AV synchrony, but generally require the placement of two separate transvenous leads. Single-lead atrioventricular synchronous pacing system (VDD) using single-pass leads has been accepted as therapeutic alternative for atrioventricular block with normal sinus node function.The aim of this study is to evaluate clinical performance of single-pass lead VDD pacing systems in 24 consecutive patients in a ten-year period.The study group includes 17 (70.8%) male and 7 (28.8%) female patients.The mean age and mean weight during pacemaker implantation was 10.4 ± 3.8 years (4-17 years) and 30 ± 11 kg (13.5-55 kg), respectively.The patients have been followed for 7-84 months (median 42 months). The percentage of atrial sensing-ventricular pacing changed from 75 to 99.9% at the last control.During the follow-up period, pacing mode was changed to VVIR due to complete loss of AV synchrony in five patients (21%). Four of them had underlying cardiac disease. In these patients loss of AV synchrony might be related to cardiac enlargement/abnormal cardiac anatomy or small atrial dipoleventricular tip length.Despite the loss of AV synchrony in post surgical AV block or dilated cardiomyopathy, single-lead VDD pacing systems can be successfully used in children with complete AV block and normal sinus node function. Patients and lead selection should be taken into consideration for the maintenance of AV synchrony.

Atrial sensing performance of a single-lead VDD pacing system during physical activities

This study was undertaken to evaluate the atrial sensing performance of a single-lead atrial synchronous-ventricular pacing system during various physical activities on late follow-up. Fourteen patients (mean age 55 ± 17 years) with a third-degree or high-degree atrioventricular block and normal sinus node function were treated with the single-lead Thera VDD (Medtronic, Inc, Minneapolis, MN) pacemaker system. Mean P-wave amplitude at implantation was 3.2 ± 1.3 mV. To assess the VDD system performance, P-wave amplitudes during various physical maneuvers (supine, sitting, deep breathing, standing, and exercise; respectively) were measured and atrial sensing was evaluated at a mean follow-up of 11 ± 4 months. During deep breathing, minimum and maximum P-wave amplitudes (0.8 ± 0.7, 1.2 ± 1.0 mV, respectively) were found to be significantly lower than the standing position (minimum, 1.1 ± 0.9, maximum, 1.4 ± ± 1.1 mV P =.02 in both). No significant difference was found during other physical maneuvers. During the testing maneuvers, atrial undersensing was observed in 8 patients (57%) at the nominal atrial sensitivity of 0.5 mV. After increasing the atrial sensitivity (0.25 mV), no sensing failure was observed in these patients. It has been concluded that Medtronic Thera VDD system is a safe and reliable device with an easy implantation technique providing effective atrioventricular synchronization. The sensing problems, which may occur on late follow-up, can be corrected successfully by reprogramming. To achieve an optimal atrial sensing function in patients with a single-lead VDD pacing, we recommend that the atrial sensing capability should be examined in various physical maneuvers.

Usefulness of echocardiography to predict inappropriate atrial sensing in single-lead VDD pacing.

Reliable atrial sensing is the prerequisite for restoration of atrioventricular synchrony in patients with single-lead VDD pacing systems. To determine echocardiographic variables associated with inappropriate atrial sensing, 21 consecutive patients with symptomatic second- or third-degree AV block and normal sinus node function were studied. Prior to implantation echocardiographic measurements of end-systolic and end-diastolic dimensions and volumes of the right atrium and right ventricle were performed. All patients underwent implantation of a Medtronic Thera VDD(d) pacemaker with a bipolar Medtronic Capsure electrode. A minimal amplitude of the unfiltered atrial electrocardiogram of > or =0.5 mV was required for permanent lead position and the atrial sensitivity was programmed below the lowest recorded value. Appropriate atrial sensing (atrial triggered ventricular paced complexes/total number of ventricular paced complexes) was assessed during 24-hour Holter monitoring and treadmill exercise testing 3 to 6 weeks after implantation. Inappropriate atrial sensing (<95% correct atrial synchronization during Holter registration and/or <97.5% during exercise testing) was present in nine patients. Right atrial volumes and the right ventricular end-diastolic volume was significantly higher, as compared to patients without inappropriate sensing (12 patients). The right atrial and diastolic volumes had the highest correlation with correct atrial sensing r = 0.83, P<0.0001). Using a postdefined cut-off value of > or =80 mL for the end-diastolic right atrial volume, sensitivity and specificity for inappropriate sensing was 100% and 92%, respectively. These findings show that preimplant echocardiography can identify patients with inappropriate sensing during VDD pacing, in whom DDD pacing should be considered.

Clinical Investigation of P Wave Amplitude and Atrial Synchronous Ventricular Pacing in Different Body Position and Physical Activity with a Single-Pass Lead VDD Pacing

Background:Single pass lead VDD pacing preserves atrioventricular synchrony with a single lead system which incorporates floating atrial electrodes. The objectives of this study were to measure whether different body postures and physical activities cause significant changes of the atrial electrogram amplitudes and to evaluate the effectiveness of its atrial sensing, ventricular sensing and pacing. Method:Prospective study was done in 7 patients with high degree AV block and normal sinus node function in whom a single lead VDD pacing system was implanted. The P wave amplitude was been measured in different condition during follow-up period. Results:1) During follow-up period, the P wave amplitude showed variation with changes in posture and respiration, but there was no consistent increase or decrease in amplitude. The lowest P wave amplitude was above the minimal atrial sensing value of 0.2 mV. 2) The percentage of atrial synchronous ventricular pacing recorded in Holter ECG and during Treadmill exercise test was more than 99%. 3) Atrial oversensing or VA cross sensing were not observed in any of the patients. Conclusions:Despite floating atrial electrode, the single pass lead VDD pacing maintains reliable atrial sensing and ventricular pacing in different body position and physical activity, so it may offer an excellent alternative in patients with high grade AV block and intact sinus node function. (Korean Circulation J 1999;29(10):1082-1088)

Predictors of loss of atrioventricular synchrony in single lead VDD pacing

ObjectiveTo evaluate maintenance of proper VDD function, defined as persistence of sinus rhythm with atrial synchronous ventricular pacing, and to define factors predicting failure of the VDD mode in patients...

Clinical reliability of single-lead VDD pacing from evaluation of p-wave sensing under dynamic conditions

In a group of 20 patients implanted with a single-lead VDD pacing system, a wide interindividual variability was found in P-wave amplitude changes occurring under dynamic conditions, even though they were of minor clinical relevance because constant atrial tracking was maintained.

Single-lead VDD pacing: Long-term experience with four different systems

Background: Previous multicenter studies have shown that single-lead VDD pacing systems provide satisfactory atrial-triggered ventricular pacing at middle term for treatment of atrioventricular block without sinus dysfunction. However, we lack data on long-term results obtained with different VDD systems implanted in a large number of patients from a single center. Methods: One hundred fifty patients (76 ± 11 years) with second- or third-degree atrioventricular block ( n = 147) or symptomatic hypertrophic cardiomyopathy ( n = 3) without sinus dysfunction were paced with four different VDD pacing systems able to sense the atrium and to pace the ventricle. Atrioventricular synchronization was assessed during follow-up by ECG and Holter monitoring. Results: Mean value of the atrial electrogram during implantation was 2.01 ± 0.94 mV without any differences among the four systems. With a mean follow-up of 24 ± 11 months, 95% of patients remain paced in VDD mode, whereas 5% have been reprogrammed in VVI or VVIR mode for permanent atrial fibrillation or loss of atrial sensing; 96% of patients with sinus atrium have atrioventricular synchronization >90% and 94% of patients have >95%, without significant difference between the four systems used. Conclusions: These different single-lead VDD systems can provide satisfactory long-term atrioventricular synchronization; results are comparable to those obtained with conventional DDD pacing systems with two leads. (Am Heart J 1998;135:1036-9.)

Use of single lead VDD pacing in children.

The development of transvenous ventricular pacing leads with proximal electrodes capable of atrial sensing and the recent availability of smaller generators has created the opportunity to treat children with complete AV block and normal sinus node function with a transvenous single lead VDD pacing system. Studies in adults have demonstrated this system to be efficacious with low complication rates. Transvenous single lead VDD pacemakers were implanted in ten children, aged 5-15 years, between December 1993 and April 1996, in our institution. The indications were complete AV block with severe bradycardia in 5 patients, second-degree or complete AV block following congenital heart surgery in 3, complete AV block with long QT syndrome in 1, and second-degree AV block and syncope in 1. There were no complications related to the procedure in any case. P and R wave amplitudes were measured and thresholds were determined intraoperatively on all patients. Amplitudes and thresholds were remeasured on seven patients with a mean follow-up of 17 months; Holter monitors were performed on seven patients with mean follow-up of 16 months. P and R wave amplitudes were generally diminished at follow-up compared to initial values but remained within an acceptable range for all patients. Four patients required reprogramming after pacemaker insertion, 1 received an atrial lead for dual chamber pacing, 1 required reposition for lead dislodgment, and 1 patient required a new lead for an inadequate ventricular pacing threshold. No patient had evidence of failure to sense or capture as evaluated by Holter monitoring at last follow-up. Single lead VDD pacing systems can be successfully used in properly selected children with high degree or complete AV block with normal sinus node function.

Determining Optimal Atrial Sensitivity Settings for Single Lead VDD Pacing: The Importance of the P Wave Histogram

In order to provide atrioventricular synchrony, VDD pacing systems require reliable atrial sensing. Variations in atrial signals with exercise and daily activities may lead to undersensing, with loss of physiological pacing. The aim of this study was to determine, for a single lead VDD pacing system, the maximal variation in atrial signals in order to facilitate optimal programming of atrial sensitivity. Fifteen patients underwent implantation of a Vitatron Saphir VDD pacemaker with a Vitatron Brilliant electrode. At a mean (+/-SD) follow-up of 67.3 +/- 38.8 days, resting P wave amplitude was compared with the P wave amplitude histogram obtained from the pacemaker, which recorded atrial signals over the preceding 30 days. Resting P wave amplitude was also compared with P wave amplitudes during variations in posture, respiration, and during exercise. P wave amplitude showed great variation with changes in posture and respiration, but there was no consistent increase or reduction. During exercise, the mean P wave amplitude fell by 36.6% +/- 31.3% compared with the resting value (P < 0.05). During daily activities, 22.6% of P wave amplitudes recorded on the P wave histogram were < 0.5 mV. The smallest P wave amplitudes were detected by the P wave histogram in 11 (79%) of 14 patients. These data suggest that atrial sensitivity may need to be programmed higher than that indicated by single readings or exercise. The P wave amplitude histogram is the most reliable indicator of the smallest atrial signal and should be used to optimize atrial sensitivity settings.

Long‐Term Follow‐Up of Patients with Single Lead VDD Stimulation

The purpose of this study was to assess the long-term results of a single lead VDD pacing system (Phymos MPS) in 85 patients (48 males, 37 females, mean age 74 +/- 9 years). The system, which incorporates two atrial floating electrodes (Phymos 830-S), was implanted for second- or third-degree Mobitz II AV block. The percentage of AV synchronized pacing, the presence of fusion beats due to short AV delay, and the occurrence of supraventricular arrhythmias was evaluated by Holter monitoring at 6-month intervals. Over a mean period of follow-up of 44 months (range 2-56), over 90% of AV synchronized pacing events were noted in 74 patients (87%). The presence of persistent fusion beats was detected in 12 patients (14%). In ten patients the pacemaker was reprogrammed to VVI mode for supraventricular arrhythmias (7 patients, 8.2%) or unsatisfactory atrial sensing (3 patients, 3.5%). One pacemaker was removed for pocket infection and two for battery depletion. These observations support the use of VDD single lead pacing to combine a physiological mode of stimulation with simple implantation techniques.

Atrial sensing performance of the single-lead VDD pacemaker during exercise

Objectives. The purpose of this study was to examine the atrial sensing performance of the single-lead VDD pacing system during exercise and concomitant changes in the amplitude of the atrial electrogram.Background. Studies of conventional dual-Chamber pacing have demonstrated an overall reduction in the atrial signal amplitude and a variable incidence of atrial undersensing during vigorous exercise.Methods. Tht telemetered atrial electrogram and simultaneous surface electrocardiogram (ECG) were continuously recorded in 12 patients (mean age 70.8 years) with an implanted single-lead VDD pacing system during treadmill stress testing, The atrial signal amplitude was measured at peak exercise, and the patients were monitored for maintained atrial synchronized ventricular pacing during the entire exercise and recovery period.Results. The atrial electrographic voltage decreased an average of 19.5% (p < 0.05) during peak exercise, and the reduced P wave amplitude ranged from 6.9% to 59.4% of the preexercise values in 8 of 12 patients. Three patients showed a modest increase in atrial signal amplitude, and one pateint had no change. The telemetered electrogram displayed persistent and intact atrial synchronous ventricular pacing throughout the study period.Conclusions. Despite relatively low atrial signal amplitudes at rest and further decreases during exercise, the single-lead VDD pacemaker maintains reliable atrial tracking and ventricular pacing during vigorous exercise.

VDD single pass lead pacing: sustained pacemaker mediated tachycardias unrelated to retrograde atrial activation.

Pacemaker mediated tachycardias (PMTs) are a well known complication of P synchronous pacing. Although the initiating mechanisms are several, all of them are associated with retrograde atrial activation, which is sensed by the atrial sensing channel, resulting in ventricular pacing. In 19 patients suffering from symptomatic AV conduction disturbances and normal sinus node function, a VDD pacing system connected to a single pass ventricular lead with dual chamber electrodes was implanted. The bipolar atrial electrode, floating in the right atrium, was used to detect endocardial atrial electrograms that were differentially processed within the pacemaker for optimal discrimination and filtering of undesirable signals. The widely programmable atrial sensitivity (amplitude and filtering) allowed stable P synchronized ventricular pacing in all patients, but in five of them, sustained PMTs not related to retrograde atrial activation was documented during the follow-up. The common mechanism for the onset and maintenance of these PMTs was traced to the abnormal sensing of the terminal forces of ventricular activation and/or of the T wave. The possibility of interferences between ventricular and atrial electrodes (crosstalk) was also considered. The reduction of atrial channel sensitivity represented in all cases the only effective procedure to prevent this type of PMT. In conclusion, the bet signal to noise ratio is an important endpoint to assure the proper function of a single lead VDD pacing system. Furthermore, using the differential amplifier built within the pacemaker, consideration should be given to the optimal mode of rejection of the terminal forces of the QRS and T wave.

European Multicenter Prospective Follow‐Up Study of 1,002 Implants of a Single Lead VDD Pacing System

European Multicenter Prospective Follow‐Up Study of 1,002 Implants of a Single Lead VDD Pacing System

A New Single Lead VDD Pacing System

In 24 patients with advanced heart block and normal sinus node function, a new single lead VDD pacing system was implanted. At implantation, the endoatrial, bipolar electrogram was recorded in all patients. The lead position was checked by means of chest X-ray. At discharge and after 1, 3, and 6 months, testing for myopotential inhibition, telemetric evaluation of the endoatrial potential, and Holter recordings were made. After discharge, 18 patients performed two cardiopulmonary exercise tests at two different rate-matched AV intervals. All investigations showed good AV synchrony and a lack of interferences by myopotentials. The maximum rate-matched AV interval provided a significantly improved exercise capacity, which was more evident in patients with signs of myocardial failure.