Symptomatology and quality of life in patients with rate-responsive pacemakers: a double-blind, randomized, crossover study

Personalised reprogramming to prevent progressive pacemaker-related left ventricular dysfunction: A phase II randomised, controlled clinical trial

BACKGROUND

Pacemakers are widely utilised to treat bradycardia, but right ventricular (RV) pacing is associated with heightened risk of left ventricular (LV) systolic dysfunction and heart failure. We aimed to compare personalised pacemaker reprogramming to avoid RV pacing with usual care on echocardiographic and patient-orientated outcomes.

METHODS

A prospective phase II randomised, double-blind, parallel-group trial in 100 patients with a pacemaker implanted for indications other than third degree heart block for ≥2 years. Personalised pacemaker reprogramming was guided by a published protocol. Primary outcome was change in LV ejection fraction on echocardiography after 6 months. Secondary outcomes included LV remodeling, quality of life, and battery longevity.

RESULTS

Clinical and pacemaker variables were similar between groups. The mean age (SD) of participants was 76 (+/-9) years and 71% were male. Nine patients withdrew due to concurrent illness, leaving 91 patients in the intention-to-treat analysis. At 6 months, personalised programming compared to usual care, reduced RV pacing (-6.5±1.8% versus -0.21±1.7%; p<0.01), improved LV function (LV ejection fraction +3.09% [95% confidence interval (CI) 0.48 to 5.70%; p = 0.02]) and LV dimensions (LV end systolic volume indexed to body surface area -2.99mL/m2 [95% CI -5.69 to -0.29; p = 0.03]). Intervention also preserved battery longevity by approximately 5 months (+0.38 years [95% CI 0.14 to 0.62; p<0.01)) with no evidence of an effect on quality of life (+0.19, [95% CI -0.25 to 0.62; p = 0.402]).

CONCLUSIONS

Personalised programming in patients with pacemakers for bradycardia can improve LV function and size, extend battery longevity, and is safe and acceptable to patients.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03627585.

Nonpharmacological Treatment of Atrial Fibrillation: What Is the Role of Device Therapy?

Atrial fibrillation is the most common arrhythmia in the adult population, and its incidence and prevalence are still rising. Cardiac devices are widely used in clinical practice in the management of various rhythm disturbances and heart failure treatment. Many patients who receive a pacemaker, implantable cardioverter-defibrillator, or cardiac resynchronization therapy also experience atrial fibrillation in the course of their life. Therefore, this review aims to describe the role of these devices in the treatment and prevention of atrial fibrillation in the device recipients. In addition, all these implantable devices also serve as permanent ECG (electrocardiogram) monitors, thus providing important information about the presence and characteristics of atrial fibrillation that may or may not be detected by the patient but can modify our therapeutical approach with regard to the stroke prevention.

Personalized Rate-Response Programming Improves Exercise Tolerance After 6 Months in People With Cardiac Implantable Electronic Devices and Heart Failure

Background:

Heart failure with reduced ejection fraction (HFrEF) is characterized by blunting of the positive relationship between heart rate and left ventricular (LV) contractility known as the force-frequency relationship (FFR). We have previously described that tailoring the rate-response programming of cardiac implantable electronic devices in patients with HFrEF on the basis of individual noninvasive FFR data acutely improves exercise capacity. We aimed to examine whether using FFR data to tailor heart rate response in patients with HFrEF with cardiac implantable electronic devices favorably influences exercise capacity and LV function 6 months later.

Methods:

We conducted a single-center, double-blind, randomized, parallel-group trial in patients with stable symptomatic HFrEF taking optimal guideline-directed medical therapy and with a cardiac implantable electronic device (cardiac resynchronization therapy or implantable cardioverter-defibrillator). Participants were randomized on a 1:1 basis between tailored rate-response programming on the basis of individual FFR data and conventional age-guided rate-response programming. The primary outcome measure was change in walk time on a treadmill walk test. Secondary outcomes included changes in LV systolic function, peak oxygen consumption, and quality of life.

Results:

We randomized 83 patients with a mean±SD age 74.6±8.7 years and LV ejection fraction 35.2±10.5. Mean change in exercise time at 6 months was 75.4 (95% CI, 23.4 to 127.5) seconds for FFR-guided rate-adaptive pacing and 3.1 (95% CI, −44.1 to 50.3) seconds for conventional settings (analysis of covariance; P =0.044 between groups) despite lower peak mean±SD heart rates (98.6±19.4 versus 112.0±20.3 beats per minute). FFR-guided heart rate settings had no adverse effect on LV structure or function, whereas conventional settings were associated with a reduction in LV ejection fraction.

Conclusions:

In this phase II study, FFR-guided rate-response programming determined using a reproducible, noninvasive method appears to improve exercise time and limit changes to LV function in people with HFrEF and cardiac implantable electronic devices. Work is ongoing to confirm our findings in a multicenter setting and on longer-term clinical outcomes.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02964650.

Heart Failure: A Palliative Medicine Review of Disease, Therapies, and Medications With a Focus on Symptoms, Function, and Quality of Life

Despite significant advances in heart failure (HF) treatment, HF remains a progressive, extremely symptomatic, and terminal disease with a median survival of 2.1 years after diagnosis. HF often leads to a constellation of symptoms, including dyspnea, fatigue, depression, anxiety, insomnia, pain, and worsened cognitive function. Palliative care is an approach that improves the quality of life of patients and their caregivers facing the problems associated with life-threatening illness and therefore is well suited to support these patients. However, historically, palliative care has often focused on supporting patients with malignant disease, rather than a progressive chronic disease such as HF. Predicting mortality in patients with HF is challenging. The lack of obvious transition points in disease progression also raises challenges to primary care providers and specialists to know at what point to integrate palliative care during a patient's disease trajectory. Although therapies for HF often result in functional and symptomatic improvements including health-related quality of life (HRQL), some patients with HF do not demonstrate these benefits, including those patients with a preserved ejection fraction. Provision of palliative care for patients with HF requires an understanding of HF pathogenesis and common medications used for these patients, as well as an approach to balancing life-prolonging and HRQL care strategies. This review describes HF and current targeted therapies and their effects on symptoms, hospital admission rates, exercise performance, HRQL, and survival. Pharmacological interactions with and precautions related to commonly used palliative care medications are reviewed. The goal of this review is to equip palliative care clinicians with information to make evidence-based decisions while managing the balance between optimal disease management and patient quality of life.

Effect of fixed-rate vs. rate-RESPONSIve pacing on exercise capacity in patients with permanent, refractory atrial fibrillation and left ventricular dysfunction treated with atrioventricular junction aBLation and bivEntricular pacing (RESPONSIBLE): a prospective, multicentre, randomized, single-blind study

Aims

Atrioventricular junction (AVJ) ablation followed by biventricular pacing is an established strategy for improving symptoms and morbidity in patients with permanent atrial fibrillation (AF), reduced left ventricular ejection fraction (LVEF), and uncontrolled ventricular rate. There is no clear evidence that such patients benefit from rate-responsive (RR) pacing.

Methods and results

This prospective, randomized, single-blind, multicentre study was designed as an intra-patient comparison and enrolled 60 patients (age 69.5 ± 11.8 years, males 63.3%, NYHA 3.0 ± 0.6) with refractory AF and reduced LVEF (mean 32.4 ± 8.3%) treated with AVJ ablation and biventricular pacing. Two 6-minute walking tests (6MWT) were performed 1 week apart: one during VVI 70/min biventricular pacing and the other during VVIR 70-130/min biventricular pacing; patients were randomly and blindly assigned to Group A (n = 29, first 6MWT in VVIR mode) or B (n = 31, first 6MWT in VVI mode). Rate-responsive activation determined an increase of 18.8 ± 24.4 m in the distance walked during the 6MWT (P < 0.001). The increase was similar in both groups (P = 0.571). A >5% increase in the distance walked was observed in 76.7% of patients. The increase in the distance walked was linearly correlated with the increase in heart rate recorded during the 6MWT in the VVIR mode (r = 0.54; P < 0.001).

Conclusion

In permanent AF patients with uncontrolled rate and reduced LVEF who had undergone AVJ ablation and biventricular pacing, RR pacing yields a significant gain in exercise capacity, which seems to be related to the RR-induced frequency during effort.

Position paper for management of elderly patients with pacemakers and implantable cardiac defibrillators: Groupe de Rythmologie et Stimulation Cardiaque de la Société Française de Cardiologie and Société Française de Gériatrie et Gérontologie

Despite the increasingly high rate of implantation of pacemakers (PMs) and implantable cardioverter defibrillators (ICDs) in elderly patients, data supporting their clinical and cost-effectiveness in this age stratum are ambiguous and contradictory. We reviewed the data regarding the applicability, safety and effectiveness of conventional pacing, ICDs and cardiac resynchronization therapy (CRT) in elderly patients. Although periprocedural risk may be slightly higher in the elderly, the implantation procedure for PMs and ICDs is still relatively safe in this age group. In older patients with sinus node disease, the general consensus is that DDD pacing with the programming of an algorithm to minimize ventricular pacing is preferred. In very old patients presenting with intermittent or suspected atrioventricular block, VVI pacing may be appropriate. In terms of correcting potentially life-threatening arrhythmias, the effectiveness of ICD therapy is similar in older and younger individuals. However, the assumption of persistent ICD benefit in the elderly population is questionable, as any advantageous effect of the device on arrhythmic death may be attenuated by higher total non-arrhythmic mortality. While septuagenarians and octogenarians have higher annual all-cause mortality rates, ICD therapy may remain effective in selected patients at high risk of arrhythmic death and with minimum comorbidities despite advanced age. ICD implantation among the elderly, as a group, may not be cost-effective, but the procedure may reach cost-effectiveness in those expected to live more than 5-7years after implantation. Elderly patients usually experience significant functional improvement after CRT, similar to that observed in middle-aged patients. Management of CRT non-responders remains globally the same, while considering a less aggressive approach in terms of reinterventions (revision of left ventricular [LV] lead placement, addition of a right ventricular or LV lead, LV endocardial pacing configuration). Overall, physiological age, general status and comorbidities rather than chronological age per se should be the decisive factors in making a decision about device implantation selection for survival and well-being benefit in elderly patients.

Validating optimal function of the closed loop stimulation sensor with high right septal ventricular electrode placement in 'ablate and pace' patients

PURPOSE

The study aim was to validate the closed loop stimulation (CLS) vs. accelerometer (ACC) rate-responsive sensors with electrodes placed in the right ventricular high septal (RVHS) or right ventricular apical (RVA) lead positions in patients following 'ablate and pace' therapy for persistent atrial fibrillation.

METHODS

'Ablate and pace' patients were randomised to either RVHS or RVA electrode placement with a dual sensor device. A double-blind crossover study comparing CLS vs. ACC rate-response pacing modes was undertaken. Subjects undertook cardiopulmonary testing with constant workload light exercise followed by a ramp protocol in addition to activity of daily living assessments.

RESULTS

Twenty subjects (14 male; age, 74 +/- 8 years) were studied. Heart rate increase was greater from lying to sitting with ACC. With mental stress, heart rate increase was greater with CLS. Peak heart rates were similar for stair ascent and descent in ACC mode. With CLS mode, however, the peak heart rate was significantly lower for stair descent. There was no difference between modes in mean response time, oxygen deficit, peak VO(2), VO(2) at anaerobic threshold, peak heart rate, total exercise time and total workload. CLS function was equally optimal at both electrode sites.

CONCLUSIONS

CLS rate adaptive pacing is appropriate for 'ablate and pace' patients, and this sensor functions equally well using RVA or RVHS lead positions.

Clinical and Quality of Life Comparison of Accelerometer, Piezoelectric Crystal, and Blended Sensors in DDDR-Paced Patients with Sinus Node Dysfunction in the Mode Selection Trial (MOST)

INTRODUCTION

Permanent pacemakers are capable of increasing heart rate in response to physical activity by a variety of sensors including accelerometers, piezoelectric crystals, or blended sensors. The impact of these different physiologic sensors on cardiovascular events and quality of life is not known.

METHODS

Of 2,010 patients randomized in the Mode Selection Trial, 1,245 patients were selected with the most commonly used pacemakers with these three sensors. Clinical characteristics and quality of life were compared between groups at baseline, 3 months, and then yearly.

RESULTS

There were 449 patients with an accelerometer sensor device, 682 with a piezoelectric sensor, and 114 with a blended sensor. The groups were similar in terms of age (mean 74 years), gender, and cardiac risk factors but differences existed in weight, heart rate, mitral regurgitation, revascularization history, and drug therapy. The median ventricular pacing frequency was 80% (25th, 75th percentiles 42, 97). After a median follow-up of 33.1 months, the risk of death, heart failure hospitalization, atrial fibrillation, and the combined endpoint of mortality and stroke was not significantly different between the sensor types, after adjustment for baseline differences. Quality of life analyses demonstrated that patients with blended sensors had significantly worse (P < 0.01) physical function than did patients with the other two sensor systems. Moreover, patients receiving blended sensors had the poorest absolute scores, without reaching statistical significance, on 9 of 13 quality of life measures after adjusting for differences in the groups.

CONCLUSION

We found no significant differences among the three most utilized sensors in clinical endpoints. Those patients who received blended sensors had worse physical function quality of life scores. However, clinical selection of the most sophisticated sensor for the most ill patients cannot be excluded as an explanation of these results.

Beat‐to‐Beat Heart Rate Adaptation in Pediatric and Late Adolescent Patients with Closed Loop Rate‐Responsive Pacemakers

The aim of this study was to evaluate the efficacy of physiological rate-responsive pacemakers (Closed Loop Stimulation--CLS) to pace pediatric and late adolescent patients undergoing rest, mental, standing, and exercise testing. Dual-chamber pacemaker is increasingly indicated for young patients. A new physiological pacing mode based on the indirect measure of ventricular contractility (CLS), has shown interesting results in adults, while no data on pediatric patients are available. RR intervals and beat-to-beat systolic and diastolic pressures were monitored in 12 pediatric patients (6 males, mean age 17 years [12-22 years]) who had a transvenous implant of Inos2+-CLS dual-chamber pacemaker (Biotronik GmbH, Berlin, Germany) and endocardial leads. All the patients showed correct electrical parameters at the implant and during the follow-ups. Paced RR intervals decreased significantly (F = 7.28, P = 0.01) from 0.85 +/- 0.08 seconds (rest) to 0.73 +/- 0.10 seconds (mental) and to 0.75 +/- 0.010 seconds (standing); systolic/diastolic pressure was significantly higher (F = 12.2, P = 0.002/F = 13.6, P = 0.001) in mental (134.4 +/- 19.9/74.4 +/- 8.1 mmHg) with respect to rest (115.1 +/- 18.3/61.0 +/- 6.1 mmHg), and standing (118.7 +/- 23.9/67.3 +/- 0.1 mmHg). During exercise the paced RR interval showed significant decrease of about 35% from baseline to maximum load (F = 24.90, P = 0.001) and systolic pressure increased significantly (F = 4.91, P = 0.019) by about 34% from baseline to maximum load. The comparison between paced and spontaneous rates showed very similar values and trend. In addition, CLS mode does not seem to overrun the spontaneous heart activity, when present. This is a study to evaluate CLS pacing in pediatric and late adolescent patients. The study shows that CLS pacing responds to both physical and non-physical stressors, providing physiological pacing rates, as previously observed in adults.

Cardiac pacing: the state of the art

Permanent cardiac pacing remains the only effective treatment for chronic, symptomatic bradycardia. In recent years, the role of implantable pacing devices has expanded substantially. At the beginning of the 21st century, exciting developments in technology seem to happen at an exponential rate. Major advances have extended the use of pacing beyond the arrhythmia horizon. Such developments include dual-chamber pacers, rate-response algorithms, improved functionality of implantable cardioverter defibrillators, combinations of sensors for optimum physiological response, and advances in lead placement and extraction. Cardiac pacing is poised to help millions of patients worldwide to live better electrically. We review pacing studies of sick-sinus syndrome, neurocardiogenic syncope, hypertrophic obstructive cardiomyopathy, and cardiac resynchronisation therapy, which are common or controversial indications for cardiac pacing. We also look at the benefits and complications of implantation in specific arrhythmias, suitability of different pacing modes, and the role of permanent pacing in the management of patients with heart failure.

Health-related quality of life measurement in heart failure: challenges for the new millennium

Health-related quality of life (HRQL), representing a patient-driven end point, has been increasingly emphasized in randomized clinical trials of new heart failure therapies. Measurement of HRQL depends on the use of validated instruments, with attention paid to the timing of administration and analysis of data in the context of conventional morbidity and mortality end points. In a review of HRQL measurement in heart failure drug trials published from 1966 to 1999, we found that important data, such as the number of participating subjects, are often lacking. HRQL is analyzed as a stand-alone end point without consideration of the underlying clinical trajectory of the disease. Improvements in trials methodology are warranted if quality-of-life data are to be meaningful in the determination of drug efficacy in heart failure.

Developments in sensor-driven pacing

This article reviews the recent major developments in the field of rate adaptive pacing. Including, the improved instrumentation of existing sensors, the use of multiple sensors to enhance sensor specificity or sensitivity, and the automation of sensor calibration. The physiologic benefits and programming of rate adaptive pacing are reviewed.

Evaluation of a dual sensor rate responsive pacing system based on a new concept. French Talent DR Pacemaker Investigators

The minute ventilation is known to be one of the most physiological indicators of exercise. A curvilinear relationship between VE and the normal sinus rhythm (NSR) has been demonstrated in healthy patients. The aim of this study is to show that a pacemaker based on a VE sensor can reproduce such a relationship. Eighty-one patients received a Talent DR 213 (ELA Medical, Montrouge, France) pacemaker with a third-generation rate responsive algorithm. At 1-month follow-up, the patients underwent a treadmill exercise test, after which three groups were defined: group 1 had 6 patients who were 100% paced throughout the exercise test; group 2 had 10 patients who maintained NSR throughout the test; and group 3 had 12 patients who had cardiopulmonary recording during the exercise test. In group 1 patients, the simulation function computed the simulated rate (sim-rate), which was compared to the sensor-driven rate (SDR). In group 2 patients, sim-rate was compared to the NSR. In group 3 patients, cardiac and metabolic reserves were compared to determine the appropriateness of the rate response to exercise (HRR% vs MR%). The results showed that the mean correlation coefficient between sim-rate and SDR was 0.983 +/- 0.005 (P < 0.001); the mean correlation coefficient between NSR and SDR was 0.92 +/- 0.07 (P < 0.001); and a linear relationship was found between HRR% and MR%, with a mean slope of 1.1 +/- 0.2 that was significantly equal to the theoretical value of 1 (P = NS). In conclusion, combining an activity-driven sensor with a physiological sensor allows the preservation of a physiological rate response during exercise.

Correlation of the heart rate-minute ventilation relationship with clinical data: relevance to rate-adaptive pacing

The heart rate (HR)-minute ventilation (VE) relationship has been shown to be nonlinear and can be expressed as two distinct straight lines. This study is to assess the correlation of the initial HR-VE slope to clinical parameters. Maximum treadmill exercise tests were performed in 100 healthy volunteers (age 19-77 years) using a ramp protocol in which work-rate increases linearly with exercise. Breath-by-breath VO2, VCO2, and VE were measured, and HR and BP were monitored throughout the exercise. The HR-VE curve demonstrated nonlinearity with a breakpoint determined by a change point analysis. This breakpoint was significantly higher than that of the anaerobic threshold. The VE at the HR-VE breakpoint was 56.4 +/- 19.4 and VE at the VE-VO2-VO2 breakpoints were 48.0 +/- 18.3 (P < 0.0001) and 40.1 +/- 16.5 (P < 0.0001), respectively. The HR at this HR-Ve breakpoint was 77.7 +/- 12.9% of the HR range. The first slope, S1 (1.76 +/- 0.64) was steeper than the second slope, S2 (0.66 +/- 0.39). Although there was a gender difference for S1, the best clinical predictor on a stepwise multiple regression analysis was body surface area (BSA) which explained 47% of the variance. It was concluded that nonlinearity of the HR-VE curve can be expressed as two straight lines. The breakpoint is beyond the anaerobic threshold and can be estimated to be approximately 75% of the maximal predicted HR. BSA is the only clinical parameter that significantly predicts the initial slope of the HR-VE curve. This can be of great importance in the programming of rate-adaptive pacemakers using a VE.

Vibration, acceleration, gravitation, and movement: activity controlled rate adaptive pacing during treadmill exercise testing and daily life activities

Activity-based sensors for rate adaptive pacing have been available for several years and now include several different types: vibration; acceleration; gravitation; and movement. However, a systematic comparison evaluating the relative advantages and disadvantages of these various sensors has received little study. The purpose of the present study was to compare these sensor subtypes using treadmill testing and an outdoor test circuit, which simulated daily life activities and included both uphill and downhill walking. Pacemakers were strapped on the chest of healthy volunteers and connected to one channel of an ambulatory recording device, which also recorded the subject's intrinsic heart rate. The pacemakers were programmed using an initial treadmill test to standardize the rate responsive parameters for each device. Nine different pacemaker models were studied including 3 vibration-based (Elite, Synchrony, Metros), 4 acceleration-based (Relay, Excel, Ergos, Trilogy), 1 gravitational-based (Swing), and 1 movement-based (Sensorithm) device. All devices demonstrated a prompt rate response with casual walking on flat ground. The vibration-, gravitational-, and movement-based pacemakers showed a pronounced rate decline during more strenuous work, e.g., walking uphill. This phenomenon was absent in the accelerometer-based units. In particular, the vibration- and movement-based units showed a higher rate with walking downhill compared to uphill. An optimally tuned rate behavior on the treadmill usually did not provide an optimal rate behavior during daily activities and there was a tendency to overstimulation during low workload. The development of the two newest sensors (gravitational and movement) did not result in an improved performance of rate response behavior. Overall, the accelerometer-based pacemakers simulated or paralleled sinus rate behavior the most closely.

Dual sensor pacemakers in children: what is the choice of sensor blending?

Dual sensor pacemakers were developed to obtain more appropriate responses to activity. We evaluated ten children with dual sensor pacemakers in different sensor blending circumstances using exercise testing to assess which ratio was optimal. Ten patients with several bradydysrhythmias (ages 6-16 years; mean 10.1 years) were included in the study. Eight patients had VVIR pacemakers (Vitatron Topaz), models and two patients had VDD pacemakers implanted via the transvenous route. All patients were in a paced rhythm (98.5% pacing). Accurate T wave sensing ranged from 81%-100%; mean 92%, median 95%. Voluntary exercise testing with a CAEP protocol was performed using a treadmill with the pacemaker in VVIR mode. Medium activity threshold with three sensor blending ratios (QT = ACT, QT > ACT, and QT < ACT) were done in all patients. The mean duration of exercise was not statistically different among the three sensor blending ratios. After 90 seconds of exercise, the mean pacing rate had increased by 12%, 3%, and 5%, respectively, in the three groups. At maximal exercise, the increases were 45%, 42%, and 54%. Mean HRs during exercise in each of the three ratios were not significantly different, although we found a statistically significant increase in HR during the first two stages of rest period in the QT = ACT sensor blending ratio compared to the QT > ACT ratio. No difference was observed after the second stage.

IN CONCLUSION

(1) there is no difference between the QT = ACT, QT < ACT, and QT > ACT sensor blending ratios; and (2) each child has to be evaluated by exercise testing to program a correct sensor blending ratio.

Oxygen uptake kinetics during low intensity exercise: relevance for rate adaptive pacemaker programming

OBJECTIVE

To establish a normal database for oxygen uptake (VO2) kinetics during low intensity treadmill exercise (LITE) testing, to be used as a guideline for programming rate adaptive pacemakers, and to determine its relation to VO2 at anaerobic threshold and peak exercise.

DESIGN

VO2 kinetics during LITE were compared with VO2 at anaerobic threshold and at peak exercise.

SETTING

LITE testing is applicable during ambulatory or hospital care and can even be performed by patients with reduced cardiac capacity.

PATIENTS

60 healthy subjects (23 women, 51.6 (SD 20.4) years; 37 men, 42.2 (16.2) years).

INTERVENTIONS

Treadmill exercise testing with "breath by breath" gas exchange monitoring using the LITE protocol for steady state, submaximal exercise, and the ramping incremental treadmill exercise (RITE) protocol for peak exercise.

MAIN OUTCOME MEASURES

Mean response time of VO2, mean oxygen deficit, and VO2 at anaerobic threshold (VO2-AT) and at peak exercise (VO2-peak) were determined.

RESULTS

(1) LITE protocol: mean response time of VO2 = 35.1 (9.9) s; oxygen deficit = 418.3 (47.9) ml; oxygen deficit/VO2 time index = 54.7 (7.4). (2) RITE protocol: VO2-AT = 22.1 (5.7) ml/kg/min; heart rate at anaerobic threshold = 120.1 (3.6) beats/min; VO2-peak = 37.6 (10.7) ml/kg/min; peak heart rate = 167.8 (19.3) beats/min. The mean response time and oxygen deficit/VO2 time index were significantly correlated to VO2-peak and VO2-AT (P < 0.01).

CONCLUSIONS

VO2 kinetics calculated in healthy controls may serve as a control database for assessing the rate response programming of pacemakers and its influence on VO2 during LITE. Because aerobic capacity below the anaerobic threshold is more likely to represent activity in daily life and the kinetics of VO2 are significantly related to VO2 at anaerobic threshold and peak exercise, LITE may provide a clinically useful correlate to peak exercise testing.

Benefits and limitations of rate adaptive pacing under laboratory and daily life conditions in patients with minute ventilation single chamber pacemakers

Rate adaptive pacing has been shown to improve hemodynamic performance and exercise tolerance during acute testing. However, there remain concerns about its benefit in daily life and possible complications incurred by unnecessary pacing. This double-blind crossover study compared the benefit of rate adaptive (SSIR) versus fixed rate (SSI) pacing under laboratory and daily life conditions in 20 rate incompetent patients with minute ventilation single chamber pacemakers (META II). The heart rate (HR) response during three different exercise tests (treadmill, bicycle ergometry, walking test) was correlated with the Holter findings during daily life in either pacing mode. The maximal HR was significantly higher in the SSIR-mode compared to the SSI-mode, both during laboratory testing (treadmill: 123 +/- 15 vs 93 +/- 29 beats/min; ergometry: 118 +/- 15 vs 89 +/- 27 beats/min; walking test: 127 +/- 9 vs 95 +/- 26 beats/min, all P values < 0.01) as well as during daily life (Holter: 126 +/- 13 vs 103 +/- 24 beats/min, P < 0.01). On Holter, the average HR (71 +/- 14 vs 71 +/- 8 beats/min) and the percentage of paced rhythm (54% vs 62%, SSI- vs SSIR-mode, P = NS) were not different in either mode. However, despite a 30% rate gain in the SSIR-mode, the exercise capacity remained unchanged, and only 38% of patients preferred the SSIR-mode. Minute ventilation pacemakers provide a physiological rate response to exercise. Irrespective of the protocol used, the findings of laboratory testing are comparable to those during daily life. However, patient selection for rate adaptive single chamber pacing should be made with caution, since the objective benefit of restoring normal chronotropy may subjectively be negligible for most patients.

Quality-of-life during DDD and dual sensor VVIR pacing

Twenty-one patients (mean age 68 +/- 8 years) with dual-sensor (QT+activity) DDDR pacemaker were randomly assigned to a crossover, double-blind study in order to evaluate their quality-of-life scores. All pacemakers were implanted for sick sinus syndrome (8 patients) or complete heart block (13 patients). The pacemakers were randomly programmed to VVIR or DDD pacing modes for 2-week periods and then the pacing mode was switched for another 2-week period. At the end of each period, the quality-of-life was evaluated by a questionnaire with regard to cardiovascular symptoms, physical activity, psychosocial and emotional functioning, and self-perceived health. Nineteen questions were scored 0-5 points each. Significant improvement in the mean total quality-of-life score (20.5 +/- 14.9 vs 34.8 +/- 17.4) as well as in dyspnea on effort, dizzy spells, palpitation, sweating, fatigue, lethargy, emotional functioning, and self-perceived health was observed during DDD compared to VVIR pacing. No question was scored in favor of VVIR pacing mode. Significant improvements during DDD pacing was demonstrated in all subgroups of patients (sick sinus syndrome, chronotropically competent and incompetent patients, and patients with high degree AV block). Eighteen patients preferred DDD pacing mode, while only one preferred VVIR pacing mode. Two remaining patients expressed no preference. The results suggest that DDD pacing offers better quality-of-life than dual sensor VVIR pacing in all subgroups of patients commonly indicated for pacemaker implantation.

Quality-of-life in DDDR pacing: atrioventricular synchrony or rate adaptation?

Although differences in exercise performance have been observed between different rate adaptive modes, the relative impact of atrioventricular (AV) synchrony and rate adaptation on quality of life (QOL) have not been determined. Thirty-three patients with either sinoatrial disease (18) or complete atrioventricular (AV) block (15) received DDDR pacemakers (16 minute ventilation sensing, 17 activity sensing). There were 11 males and 22 females, with a mean age of 66 +/- 1 (range 39-78) years. The study was a double-blind, triple cross-over study comparing DDDR, DDD, and VVIR modes. At the end of each 8-week study period in each mode, QOL was assessed by a questionnaire evaluating patients' functional class (Classes I-IV), physical malaise inventory (41 items), illness perception (43 items), and overall QOL rating based on a 48 items measure covering different aspects of the patients' daily life adjustment. Two patients required early crossover from VVIR mode during the study. Patients experienced significantly fewer physical malaise such as temperature intolerance, dyspnea, and palpitations in the DDDR mode, compared with either DDD or VVIR pacing. DDDR pacing reduced the perception of illness in 5 of 43 items compared to VVIR pacing, and improved stamina and appetite compared to DDD pacing. The overall QOL score was 102 +/- 2, 105 +/- 2, 113 +/- 2 in the DDDR, DDD, and VVIR modes, respectively, with a higher score indicating a poorer QOL (DDDR/DDD vs VVIR, P < 0.02). There was no change in functional classes between the three pacing modes.(ABSTRACT TRUNCATED AT 250 WORDS)

Permanent cardiac pacemakers in the elderly

OBJECTIVE

To review (1) Changes in cardiac impulse generation, conduction, and ventricular filling in normal aging and disease; (2) Pacemaker technology and nomenclature; (3) Expert guidelines about pacemaker use; (4) Studies of pacemaker effectiveness and utilization.

DESIGN

Articles were identified through a Medline search, review of articles' bibliographies, and contact with pacemaker manufacturer representatives for information on device features and costs. These articles were reviewed, and the relevant data are presented.

RESULTS

Abnormalities in impulse generation and conduction are common in the elderly. Pacemaker use is higher in the elderly than in other population groups. Hemodynamic changes associated with aging include an increased contribution of atrial contraction to ventricular filling. Pacemakers, which maintain the synchrony between the atria and ventricles, may be particularly advantageous in the elderly for this reason. Rate-responsive ventricular pacemakers improve the quality of life compared with fixed rate devices in some patients over the age of 75. Dual-chamber, sequential pacemakers are more likely to reduce symptoms of pacemaker syndrome than ventricular pacemakers and probably also prolong survival and reduce risk of atrial fibrillation in certain groups of patients. However, dual chamber devices are more expensive and require more frequent follow-up. Pacemaker utilization can vary widely by region. Decisions about pacemakers require explicit tradeoffs between risk and quality of life on one hand and cost on the other. In many clinical situations, there is controversy as to whether pacemakers should be used.

CONCLUSIONS

Pacemakers provide definite benefits to some patients, whereas in others, the likelihood of benefit is uncertain. More sophisticated devices may provide some additional benefit, but they are more costly. Further data is still required to define precisely which groups of patients substantially benefit from complex and expensive pacing modalities compared with simpler ones.

Initial experience with a new single chamber, dual sensor rate responsive pacemaker. The Topaz Study Group

In August 1991, a new single chamber pacemaker became available that utilizes information from two sensors, activity and stimulus-to-T wave (QT) interval. We are reporting on the first 90 implants in 21 centers. T wave sensing was adequate at implantation in 88/90 patients, with a safety margin of > 100% in 86/90. Activity sensing was adequate in all patients. The contribution of each sensor (sensor blending) is programmable for each patient. Of 75 patients assessed at 1 month after implant, three have been programmed to "Activity-Only" mode, and 72 to dual sensor mode. Of these, 18 have been programmed to "QT < Activity," 48 to "QT = Activity," and 6 to "QT > Activity." Forty-five patients underwent exercise testing in dual sensor mode and a subgroup of 15 also underwent exercise testing in Activity-Only mode. The dual sensor mode produced a more gradual increase in pacing rate. Sensor Cross Checking satisfactorily prevented a sustained high pacing rate in tests of false-positive activity sensing (tapping, vibrating pacemaker, or static pressure). The maximum pacing rate on walking downstairs (94.2 +/- 7.2 ppm) was similar to that produced by walking upstairs (91.6 +/- 5.9 ppm). We conclude that initial assessment of this dual sensor, single chamber, rate responsive pacemaker confirms that the algorithm for combining data from two sensors functions satisfactorily. Dual sensor rate responsive pacing may offer significant advantages over single sensor devices, and further studies of this novel device are indicated.

The Dutch version of the Nottingham Health Profile: investigations of psychometric aspects

Data on the adaptation, reliability, and validity of the Dutch version of the Nottingham Health Profile are discussed. The linguistic adaptation of the English version into Dutch is described, followed by the field-testing procedure and the analyses of data from 276 selected subjects from an average general medical group practice in a village nearby Rotterdam. The internal consistency, Cronbach alphas, of the subscales varied from .70 to .85. Test-retest measures for 51 patients with cardiac problems gave Spearman correlations from .69 to .92, while the interscale relationships yielded six relatively independent areas of discomfort and stress. By means of logistic regression analysis on differences between old versus young, male versus female, and healthy versus ill individuals, discriminant validity was satisfactory. Findings suggest that the psychometric aspects of the Dutch version, also seen from a cross-cultural point of view, are sufficient. Nevertheless, further research on reliability and validity of the Dutch version is required to establish its usefulness with different patient groups.

The Danish version of the Nottingham Health Profile: its adaptation and reliability

OBJECTIVE

To test the reliability of the Danish version of the Nottingham Health Profile.

DESIGN

Test-retest reliability with an interval of four weeks between administrations of the measure.

SETTING

Copenhagen.

PARTICIPANTS

Seventy patients suffering from osteoarthrosis, living at home and awaiting hip-replacement operation. The patients' ages ranged from 37 to 90 years, with a median of 72 years.

OUTCOME MEASURE

The Danish version of the Nottingham Health Profile, a measure of perceived health status, widely used in Europe. The measure consists of six sections; pain, physical mobility, energy level, sleep, social isolation, and emotional reactions.

RESULTS

The respondents scored highly on the measure, particularly on the pain, physical mobility, and energy sections. No major differences in scores associated with age or sex were found. The test-retest correlation coefficients obtained for the six sections were high (ranging from 0.76 to 0.86) and comparable with those found in Sweden and the UK. The test-retest correlation for the whole measure was 0.93.

CONCLUSION

The Danish version of the Nottingham Health Profile has been shown to be reliable and to be acceptable and relevant to patients with chronic disability. Should the formal tests of validity currently in progress prove satisfactory, Danish clinicians and researchers will have a valuable tool available for gaining insight into the impact of illness and its treatment on patients.

Quality-of-life in patients treated with atrioventricular synchronous pacing compared to rate modulated ventricular pacing: a long-term, double-blind, crossover study

To investigate whether the preservation of atrioventricular (AV) synchronization matters for quality-of-life during pacemaker treatment we assessed 17 consecutive patients with high degree AV block and preserved sinus node function in a double-blind, long-term crossover study. A questionnaire with regard to cardiovascular symptoms, sleep disturbances, cognitive functioning, physical ability, social interaction, emotional functioning, and self-perceived health was completed after 2 months of atrial synchronous (DDD) and rate modulated ventricular pacing (VVI,R), respectively. A significant improvement in shortness of breath, dizziness and palpitations as well as an improvement of cognitive functioning was observed during DDD pacing. Nine patients preferred the DDD mode and three the VVI,R mode. The remaining five patients did not express any preference. The preference for the DDD mode was explained by a significant reduction of cardiovascular symptoms and an improved self-perceived health, physical ability, and psychological well-being during DDD pacing. All differences in quality-of-life parameters between the two modes of pacing favored the DDD mode and no adverse effects of this mode were found. Thus, the maintenance of AV synchrony adds further symptomatic relief compared to rate increase alone. The results indicate that DDD pacing is the preferred mode of pacing in patients with high degree AV block and preserved sinus node function.

The range of sensors and algorithms used in rate adaptive cardiac pacing

Implantable sensors play an important role in physiological cardiac pacing. Sensors can be classified according to the technical methods in which sensing is achieved: the sensing of the evoked ventricular response, intrathoracic impedance and body acceleration forces, and the incorporation of special sensors on pacing electrodes. These sensors differ in their relative merits in terms of speed, proportionality, sensitivity, and specificity of rate response. The efficacy of a sensor can be significantly modified by the algorithm used in relating sensor signal to a pacing rate change. The currently available types of sensors and algorithms are summarized and compared in this review article. The relative merits of these sensors and algorithms form the basis for designing a multisensor pacing system.

Quality of life in patients with rate responsive pacemakers: a randomized, cross-over study

Eleven patients with rate responsive pacemakers (7 men, 4 women, mean age 41 years with a range of 23-60) were randomly assigned to a cross-over study in order to assess their overall exercise capacity and quality-of-life (QOL) scores. All of the pacemakers were implanted for complete AV block or sick sinus syndrome. The pacemakers were randomly programmed into VVI or rate responsive (VVIR) pacing modes for 3-week study periods in each mode. At the end of each period, an exercise test was performed and the QOL was evaluated by the "Hacettepe Quality-of-Life Questionnaire". All patients exercised longer in the VVIR mode (mean 10.54 +/- 0.73 min) than in the VVI mode (mean 7.81 +/- 0.62 min) (P less than 0.05). QOL scores were also found to be significantly higher in the VVIR mode (mean 173.81 +/- 16.22 points) compared to the VVI mode (mean 156.27 +/- 21.22 points) (P less than 0.01). In conclusion, our results suggest that VVIR pacing offers a better QOL in addition to an improved exercise capacity, compared to the single chamber nonrate modulated pacing (VVI).

Activity-sensing rate responsive versus conventional fixed-rate pacing: a comparison of rate behavior and patient well-being during routine daily exercise

Rate responsive single chamber pacing (VVIR) may be the pacemaker of choice in patients who are not suitable candidates for a dual chamber system. Several studies, most of them performed in an exercise laboratory, have shown a significantly higher exercise capacity demonstrating an improvement in cardiac output and anaerobic threshold compared to conventional fixed rate pacing (VVI). Expressing our idea that stress testing in an "artificial environment" on a bicycle or motor driven treadmill has its limitations and may be difficult to extend into patient's daily life, we designed an outdoor study imitating patient's daily activity. Twenty-one patients with an activity-sensing rate responsive pacemaker performed in a double blind fashion in VVI and VVIR mode the following test circuit: walking 170 meters on flat ground, 210 meters incline, climbing a flight of stairs, and the same circuit in reverse order, and therefore "downhill". Heart rate behavior was recorded by Holter monitoring and patients subjective feelings of well-being, i.e. fatigue and dyspnea were also evaluated. VVIR pacing responded promptly to exercise, i.e., walking on a flat ground, but no further significant increase in pacing rate was observed in relationship to the strength of physical activity while walking inclined or climbing stairs. While patients became exhausted, a nonphysiological decrease in heart rate sometimes occurred. Despite these limitations 6 of 12 patients who had a paced-only rhythm while exercising in both VVI and VVIR mode reported feeling significantly better in the VVIR mode, expressing less dyspnea and fatigue. In contrast, two of nine patients having only intermittently paced rhythm preferred the VVIR mode. Patients with lower ejection fraction (EF) were more likely to show subjectively a benefit while exercising in VVIR mode, compared to those with less reduced or normal EF. Despite the technical limitations of using a piezo crystal for rate adaptation, VVIR pacing is an important option in paced-only patients, but it seems less beneficial in patients with only intermittent paced rhythm.

A simultaneous, noninvasive comparison with sinus rhythm, of two activity sensing, rate adaptive pacemakers, in an elderly population

We compared the rate response to low level work, arm exercise, step testing, and treadmill exercise between the Siemens Sensolog 703 S (Sg) and the Medtronic Activitrax (Ax) pacemakers, and simultaneous sinus rhythm (SR) in an elderly population. In ten subjects mean age 70.6 years, range 49-81 years, the pacemaker responses were noninvasively compared by strapping the units to the chest wall under constant and equal pressure applied by an adjustable belt. Pacemaker rates and SR were recorded simultaneously on a three-channel ECG recorder. The units were programmed in situ to give an increase in rate from 70 beats/min sitting, to 100 beats/min after walking at a normal pace for 30 seconds. Programming took three times longer for Sg (P less than 0.02). The response to standing and bending was poor for both units (Ax mean 75.7 beats/min, Sg mean 77.6 beats/min), when compared to SR (mean 90.3 beats/min). A 20-step test resulted in a greater rate response from Ax (mean 105.3 beats/min) than from Sg (mean 96.3 beats/min [P = 0.09]), though both were still less than SR (116.3). There were significant differences between the two pacemakers on treadmill testing, at peak rate achieved (Ax mean 112.5 beats/min; Sg mean 102.7 beats/min [P less than 0.005], SR mean 122.5 beats/min) and at end exercise (Ax mean 112.5 beats/min; Sg mean 92.9 beats/min [P less than 0.002], SR mean 121.3 beats/min). Arm exercise, however, resulted in a significantly greater response from Sg than Ax (105.1 and 88.5 beats/min, respectively; P less than 0.01, SR 98.7 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)