A Leadless Intracardiac Transcatheter Pacing System

Permanent Leadless Cardiac Pacemaker Therapy

A new technology, leadless pacemaker therapy, was recently introduced clinically to address lead- and pocket-related complications in conventional transvenous pacemaker therapy. These leadless devices are self-contained right ventricular single-chamber pacemakers implanted by using a femoral percutaneous approach. In this review of available clinical data on leadless pacemakers, early results with leadless devices are compared with historical results with conventional single-chamber pacing. Both presently manufactured leadless pacemakers show similar complications, which are mostly related to the implant procedure: cardiac perforation, device dislocation, and femoral vascular access site complications. In comparison with conventional transvenous single-chamber pacemakers, slightly higher short-term complication rates have been observed: 4.8% for leadless pacemakers versus 4.1% for conventional pacemakers. The complication rate of the leadless pacemakers is influenced by the implanter learning curve for this new procedure. No long-term outcome data are yet available for the leadless pacemakers. Larger leadless pacing trials, with long-term follow-up and direct randomized comparison with conventional pacing systems, will be required to define the proper clinical role of these leadless systems. Although current leadless pacemakers are limited to right ventricular pacing, future advanced, communicating, multicomponent systems are expected to expand the potential benefits of leadless therapy to a larger patient population.

Complications with the MICRA TPS Pacemaker System: Persistent Complete Heart Block and Late Capture Failure

A Medtronic MICRA transcatheter pacing system (Medtronic, Minneapolis, MN, USA) was implanted in an 86-year-old patient with sick sinus syndrome and left bundle branch block after transfemoral aortic valve implantation. During implantation she developed a persistent complete heart block due to manipulation with the large-bore delivery catheter. Two weeks later, acute pacemaker dysfunction occurred due to massive increase of pacing threshold and impedance without obvious pacemaker dislocation or myocardial perforation. Recurrent capture failure was seen with pacing output set at 5 V/1.0 ms. Hence, microdislocation or fixation of the tines in the right ventricular trabeculae has to be assumed.

Eligibility of Pacemaker Patients for Subcutaneous Implantable Cardioverter Defibrillators

INTRODUCTION

The subcutaneous implantable cardioverter defibrillator (ICD) has emerged as a viable therapeutic option for patients who are deemed high risk for sudden cardiac death. Previous studies have shown that 7-15% of patients are not candidates for the S-ICD based on their intrinsic QRS/T-wave morphology. Presently, it is not known if the S-ICD can be considered as supplementary therapy in patients who are ventricularly paced. We sought to determine the proportion of ventricularly paced patients who would qualify for an S-ICD.

METHODS AND RESULTS

We evaluated 100 patients with transvenous pacemakers/ICDs, including 25 biventricular devices to determine S-ICD candidacy during right ventricular (RV) pacing and biventricular pacing based on the recommended QRS:T-wave ratio screening template. Fifty-eight percent of patients qualified for an S-ICD based on their QRS morphology during ventricular pacing. More patients during biventricular pacing met criteria compared to during RV pacing alone (80% vs. 46%, P <0.01). Patients that were paced from the RV septum were more likely to qualify compared to those paced from the RV apex (67% vs. 37%, respectively, P <0.01).

CONCLUSION

While S-ICD implantation may be considered as supplemental therapy in select patients with preexisting transvenous devices, relatively fewer candidates who are paced from the RV apex qualify. QRS morphologies generated from biventricular pacing as well as from septal RV pacing are more likely to screen in based on the recommended S-ICD template.

Venous Hemodialysis Catheters and Cardiac Implantable Electronic Devices: Avoiding a High-Risk Combination

End-stage renal disease is frequently accompanied by cardiac comorbidity that warrants treatment with a cardiovascular implantable electronic device (permanent pacemaker or implantable cardioverter-defibrillator). In the United States, chronic hemodialysis (HD) population, cardiac implantable devices are present in up to 10.5% of patients; a venous HD catheter is utilized for blood access in 18% of prevalent patients. The concomitant presence of a venous HD catheter and cardiovascular implantable device creates a high-risk circumstance, with potential for causing symptomatic central venous stenosis, and for developing complicated endovascular infection. This dangerous combination may be avoided for many patients by utilizing nondialysis methods for management of advanced chronic kidney disease, initiating dialysis without venous catheter access, or managing cardiac rhythm disorders without use of transvenous cardiac implantable electronic devices. In those situations where the combination of a venous HD catheter and cardiac implantable device is unavoidable, there are strategies to minimize duration of venous catheter access, and to reduce risks for infectious complications. It is essential for nephrologists and cardiologists to understand the indications, alternatives, and risks involved with venous HD access and cardiac implantable devices. Coordinated management of renal disease and cardiac rhythm disorders has potential to minimize risks, improve outcomes, and substantially reduce the cost of care.

Lead or be led: an update on leadless cardiac devices for general physicians

Implantable cardiac devices have an increasingly important role. Pacemakers remain the only effective treatment for symptomatic bradycardia; cardiac resynchronisation therapy is a proven treatment for heart failure; and implantable cardioverter defibrillators (ICD) are superior to medical therapy in prevention of sudden cardiac death. Our ageing population has led to a rising number of device implants. Physicians in all specialties increasingly encounter patients with cardiac devices and require an understanding of their capabilities and functions. The rising prevalence of implantable devices has been matched by a parallel expanse in device technology. Leadless devices have become a reality and represent the future of device therapy. The absence of a transvenous lead offers a significant clinical advantage because of many well established issues related to lead complications. The leadless pacemaker and subcutaneous ICD are significant new products that are currently not well recognised or understood by general physicians.

Leadless Pacemakers

Leadless pacing is an emerging technology with the potential to significantly improve outcomes associated with the need for long-term pacing. Specifically, the major advantage of leadless systems is abolishing the need for transvenous leads and subcutaneous pockets, both of which account for most adverse events associated with traditional pacemakers. Two leadless pacemakers are currently available: the Nanostim (leadless cardiac pacemaker [LCP]) device (St. Jude Medical, Sylmar, California) and the Micra Transcatheter pacing system (Medtronic, Minneapolis, Minnesota). These 2 pacemakers have shown promising results in clinical trials. In conclusion, in this review we summarize the results of the 2 investigational device exemption trials and compare the pros and cons of these devices to traditional transvenous pacemakers.

End-of-life Management of Leadless Cardiac Pacemaker Therapy

The clinically available leadless pacemakers for patients with a single-chamber pacing indication have shown to be safe and effective. However, the optimal end-of-life strategy of this novel technique is undefined. Suggested strategies comprise of (a) placing an additional leadless device adjacent to the leadless pacemaker, or (b) retrieving the non-functioning leadless pacemaker and subsequently implanting a new device. Although initial studies demonstrate promising results, early experience of acute and mid-term retrieval feasibility and safety remains mixed. We suggest that the approach of leadless pacemaker retrieval is more appealing to limit the amount of non-functioning intracardiac hardware. In addition, potential risks for device-device interference, and unknown long-term complications associated with multiple intracardiac devices are prevented. The potential inability to retrieve chronically implanted leadless pacemakers limits the application of this novel technology. Therefore, long-term prospective analysis is required to define the most optimal end-of-life strategy.

Anaesthetic consideration in patients with cardiac implantable electronic devices scheduled for surgery

With advances in cardiology and cardiothoracic surgery, several newer implantable cardiac devices have become common in the surgical population. Multichamber pacemakers, implanted cardiac defibrillators and ventricular assist devices are frequent in current day practice. Many of the newer implantable cardiac electronic devices are targeted at managing heart failure. While managing such patients for non-cardiac surgeries, specific issues related to equipment characteristics and troubleshooting should be a priority for the anaesthesiologists. There is a possibility of malfunction of the devices resulting in catastrophic outcomes. Therefore, it is imperative to understand the pathophysiology, device characteristics and troubleshooting before embarking on anaesthetising patients with implantable cardiac electronic devices.

The Micra Leadless Transcatheter Pacemaker. Implantation and Mid-term Follow-up Results in a Single Center

INTRODUCTION AND OBJECTIVES

Currently, studies on the leadless pacemaker (Micra) have mostly been limited to clinical trials with less than 6 months' follow-up and they often fail to reflect real population outcomes. We sought to evaluate electrical parameters at implantation and chronologically during follow-up, as well as the safety of this new technique.

METHODS

This prospective, observational study included 30 consecutive patients, all ≥ 65 years, with an indication for single-chamber pacemaker implantation.

RESULTS

Successful implantation was accomplished in all patients referred for leadless implantation. The mean age was 79.4±6.4 years (range, 66-89 years); 20 (66.6%) were men and 28 had permanent atrial fibrillation (93.3%); 1 had atrial tachycardia and 1 had sinus rhythm. Concomitant atrioventricular node ablation was performed immediately after implantation in 5 patients (16.6%), and implantation was performed after transcatheter aortic valve implantation in 2. The procedure was performed under an uninterrupted anticoagulation regimen (maximum INR 2.4) in 23 patients (76.6%). With the exception of 1 moderate pericardial effusion without tamponade, there were no severe complications. The mean follow-up was 5.3±3.3 months and 4 patients had more than 1 year of follow-up. Sensing and pacing parameters were stable both at implantation and during the short- to mid-term follow-up.

CONCLUSIONS

Implantation of leadless pacemakers is feasible, safe and provides advantages over the conventional system. Further studies with longer follow-up periods will be needed before these devices become widely used in routine clinical practice.

Retrieval of the Leadless Cardiac Pacemaker

Background—

Leadless cardiac pacemakers have emerged as a safe and effective alternative to conventional transvenous single-chamber ventricular pacemakers. Herein, we report a multicenter experience on the feasibility and safety of acute retrieval (<6 weeks) and chronic retrieval (>6 weeks) of the leadless cardiac pacemaker in humans.

Methods and Results—

This study included patients enrolled in 3 multicenter trials, who received a leadless cardiac pacemaker implant and who subsequently underwent a device removal attempt. The overall leadless pacemaker retrieval success rate was 94%: for patients whose leadless cardiac pacemaker had been implanted for <6 weeks (acute retrieval cohort), complete retrieval was achieved in 100% (n=5/5); for those implanted for ≥ 6 weeks (chronic retrieval cohort), retrieval was achieved in 91% (n=10/11) of patients. The mean duration of time from implant to retrieval attempt was 346 days (range, 88–1188 days) in the chronic retrieval cohort, and nearly two thirds (n=7; 63%) had been implanted for >6 months before the retrieval attempt. There were no procedure-related adverse events at 30 days post retrieval procedure.

Conclusions—

This multicenter experience demonstrated the feasibility and safety of retrieving a chronically implanted single-chamber (right ventricle) active fixation leadless pacemaker.

Clinical Trial Registration—

URL: https://www.clinicaltrials.gov . Unique identifiers: NCT02051972, NCT02030418, and NCT01700244.

A Review of the Key Clinical Trials of 2015: Results and Implications

INTRODUCTION

Multiple significant, potentially practice changing clinical trials in cardiology have been conducted and subsequently presented throughout the past year.

METHODS

In this paper, the authors have reviewed and contextualized significant cardiovascular clinical trials presented at major international conferences of 2015 including American College of Cardiology, European Association for Percutaneous Cardiovascular Interventions, American Diabetes Association, European Society of Cardiology, Transcatheter Cardiovascular Therapeutics, Heart Rhythm Congress, and the American Heart Association Scientific Sessions.

RESULTS

The authors describe new trial data for heart failure (including eplerenone, finerenone, patiromer, sacubitril/valsartan, the beta 3 agonist mirabegron, sitagliptin, empagliflozin, alginate-hydrogel LV epicardial implant), anticoagulation (idarucizumab and andexanet alfa reversal agents, adherence programmes, practice in ablation), transcatheter aortic valve replacement (long-term data, valve-in-valve use, the TriGuard embolic deflecting device), patent foramen ovale closure, cardiovascular prevention (PCSK9 inhibitors, hypertension treatment) and antiplatelets strategies (extended duration therapy with clopidogrel or ticagrelor). Trial data are also described for contemporary technologies including the Biofreedom polymer-free drug coated stent, bioabsorbable stents, PCI strategies, left main treatment, atrial fibrillation ablation techniques, leadless pacemakers and the role of coronary computed tomographic angiography.

CONCLUSIONS

This paper summarizes and contextualizes multiple pertinent 2015 clinical trials and will be of interest to both clinicians and cardiology researchers.

Spanish Pacemaker Registry. Thirteenth Official Report of the Spanish Society of Cardiology Working Group on Cardiac Pacing (2015)

INTRODUCTION AND OBJECTIVES

We describe the results of the analysis of the devices implanted and conveyed to the Spanish Pacemaker Registry in 2015.

METHODS

The report is based on the processing of information provided by the European Pacemaker Patient Identification Card.

RESULTS

We received information from 111 hospitals, with a total of 12 555 cards, representing 32.1% of all the estimated activity. The use of conventional generators and resynchronization devices was 820 and 73 units per million population, respectively. The mean age of the patients receiving an implantation was 77.7 years, and more than 50% of the devices were implanted in patients over 80 years of age. Overall, 58.6% of the implants and 58.8% of the replacements were performed in men. All of the endocardial leads employed were bipolar, 81.5% had an active fixation system, and 16.5% were compatible with magnetic resonance. Although dual chamber sequential pacing continues to be more widespread, pacing with VVI/R mode is used because up to 23.8% of the patients with sinus node disease are in sinus rhythm, as are 24.1% of those with atrioventricular block.

CONCLUSIONS

The total use of pacemaker generators in Spain has increased by about 5% with respect to 2014. The majority of the leads implanted are of active fixation, and less than 20% are protected from magnetic resonance. The factors directly related to the selection of pacing mode are age and sex. In around 20% of patients, the choice of the pacing mode could be improved.

Leadless pacemaker implantation in a patient with complex congenital heart disease and limited vascular access

Management of rhythm related issues might be particularly challenging in patients with congenital heart disease due to complex anatomy and restricted vascular access. The leadless technology appears a suitable and attractive alternative for this population. We describe a patient with single ventricle physiology who successfully underwent implantation of a leadless pacemaker.

Implantable cardioverter defibrillator management: an update

Implantable cardioverter defibrillator (ICD) is the cornerstone of primary and secondary prevention of sudden cardiac death. In 35 years of technologic improvement and clinical trials, there has been a continuous increase in implantation rate. Purpose of this review is to point out and discuss every aspect related to actual ICD management, investigating implantation procedure and predischarge care, office and remote monitoring follow-up, diagnostic evaluations, management of patients with suspected therapies or malfunctions, heart failure, surgery, radiotherapy and endoscopic procedures. Also, ICD backface such as infections and other complications will be discussed. Finally, we will focus on interesting future perspectives for this setting of patients.

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.

Transcatheter leadless pacemaker implantation in a patient with a transvenous dual-chamber pacemaker already in place

An 83-year-old lady had a DDDR pacemaker inserted in 1997 for symptomatic atrioventricular block. She underwent battery replacement in 2008. In 2010, she developed atrial fibrillation; the pacemaker was switched to VVIR mode. During the last 2years, ventricular lead threshold increased progressively. In December 2015, she presented for elective battery replacement. After successful battery replacement, the ventricular lead threshold remained high; therefore, we implanted a leadless transcatheter pacemaker, via femoral vein access, using a dedicated catheter delivery system. Electrical measurements at this stage revealed a pacing threshold of 0.28V at 0.24msec, and an impedance of 650Ω.

Temporary leadless pacing in a patient with severe device infection

A 64-year-old patient underwent implantation of a transcatheter pacing systems (TPS) for severe lead endocarditis. The patient experienced fever after a dental procedure. On the transoesophageal echocardiogram (TEE), vegetations were attached to the leads. Because the patient was pacemaker dependent, a temporary pacing lead had to be placed. After removal, however, he did not improve. A second TEE showed new vegetations. Ventricular fibrillation occurred spontaneously; so isoprenalin had to be stopped and a new lead was implanted. Vegetations appeared soon after the new temporary lead was placed. We used a TPS as a bridging device, followed by implantation of a resynchronisation system, and explantation of the TPS. After the Micra TPS was implanted, the patient recovered noticeably. All inflammation parameters were negative and an additional (18)F-fluorodeoxyglucose-positron emission tomography/CT imaging also proved to be negative. So a CRT-D device was then implanted, and the TCP was removed.