Pathophysiology of dyssynchrony: of squirrels and broken bones

The genesis of cardiac resynchronisation therapy (CRT) consists of ‘bedside’ research and ‘bench’ studies that are performed in series with each other. In this field, the bench studies are crucial for understanding the pathophysiology of dyssynchrony and resynchronisation. In a way, CRT started with the insight that abnormal ventricular conduction, as caused by right ventricular pacing, has adverse effects. Out of this research came the ground-breaking insight that ‘simple’ disturbances in impulse conduction, which were initially considered innocent, proved to result in a host of molecular and cellular derangements that lead to a vicious circle of remodelling processes that facilitate the development of heart failure. As a consequence, CRT does not only correct conduction abnormalities, but also improves myocardial properties at many levels. Interestingly, corrections by CRT do not exactly reverse the derangements, induced by dyssynchrony, but also activate novel pathways, a property that may open new avenues for the treatment of heart failure.     

Premature ventricular contractions in patients with an implantable cardioverter defibrillator cardiac resynchronization therapy device: Results from the UMBRELLA registry

BackgroundPremature ventricular contractions (PVC) are known to reduce the percentage of biventricular (BiV) pacing in patients with cardiac resynchronization (CRT), decreasing the clinical response. The aim of this study was to evaluate the prevalence of a high PVC burden, as well as therapeutic action (pharmacotherapy, catheter ablation or device programming), in a large CRT implantable-defibrillator (CRT-D) population.MethodsPatients with a CRT-D device from the UMBRELLA multicenter prospective remote monitoring registry were included. The PVC count was collected from each remote monitoring transmission. Patients were divided into two high (≥1 transmission ≥200/≥400 PVC/h, respectively) and one low (all transmissions <200 PVC/h) PVC count groups. The PVC burden following a high PVC count transmission was calculated.ResultsOf 1268 patients, 135 (11%) and 43 (3.4%) presented high PVC count (≥200/≥400 PVC/h, respectively). The majority of patients in the high PVC groups were not treated (61 [79%] and 32 [74%], respectively. Considering the untreated patients in the high PVC groups, median PVC/h was 199 (interquartile range [IQR]: 196) and 271 (IQR: 330), respectively. The PVC burden (proportion of time with PVC/h ≥ 200/≥400) was 40% (IQR 70) and 29% (IQR 59), respectively.ConclusionA significant proportion of CRT-D patients presented a high PVC count, however, few received treatment. In the untreated patients with a high PVC count, the PVC burden during follow-up varied substantially. Several consecutive recordings of a high PVC count should be warranted before considering therapeutic action such as catheter ablation.     

Differences in pacemaker programming between electrophysiology specialists and other physicians

BackgroundAppropriate programming of cardiovascular implantable electronic devices (CIED) is essential to ensure adequate function and avoid harmful effects. In underdeveloped countries, CIED monitoring and programming are often performed by physicians involved in their implantation. However, many of them often do not have sufficient training in CIED programming.ObjectiveWe aimed to assess the differences in pacemaker programming between electrophysiology (EP) specialists and other physicians.MethodsWe retrospectively reviewed changes in pacemaker programming performed by an EP specialist in patients who attended for pacemaker evaluation and reported previous follow-ups by a non-EP specialist.ResultsAmong 58 patients (26 males), 41 patients (71%) had programming errors and required setting modifications. The rate adaptative pacing function (R-mode) was incorrectly deactivated in 9 patients (15%) and improperly activated in 2 patients (3%). Unnecessary ventricular stimulation was detected in 23 patients (40%) with a pacing burden of 60% (32–95%). The lower rate limit was unnecessarily high in 12 patients (21%).Atrial or ventricular pacing output was inappropriate in 15 patients (26%) and was consequently modified (4 patients unnecessarily high, 9 patients below requirements). The auto-adapted pacing output was switched off in 17 of 18 patients (16 due to physician's preference, and 1 due to algorithm inaccuracy). The programmed sensitivity was inaccurate in 2 patients (3%). In 2 patients (3%) switching from DDDR to VVIR mode was required.ConclusionWe found a high prevalence of errors in pacemaker programming by non-EP specialists. An EP specialist should always be responsible for CIED follow-up.     

Novel Technique of Dual Chamber Pacing Through Minithoracotomy and Transatrial Endocardial Active Fixation Lead Insertion for Epicardial Pacing Lead Malfunction

Epicardial pacing lead fixation is employed in patients with cavopulmonary anastamosis (Glenn shunts) when they need permanent pacing. Epicardial pacing in these patients may malfunction due to high pacing thresholds or diaphragmatic pacing. A novel technique of transatrial insertion of two endocardial screw-in pacing leads through right anterolateral minithoracotomy could achieve synchronous atrioventricular pacing in a patient with Ebsteins anomaly with symptomatic sinoatrial and atrioventricular nodal disease.     

Leadless pacemaker implantation for pediatric patients through internal jugular vein approach: A case series of under 30 kg

BackgroundWe demonstrate a case series of 8 pediatric patients, all under 30 kg, who had leadless pacemaker implants via the internal jugular vein.MethodsA retrospective review of pediatric leadless pacing placement via the internal jugular vein at the University of Minnesota Masonic Children's Hospital and UC Davis Medical Center from 2018 through 2021 was performed. Rationales for pacing, demographics of patients, pacing thresholds, and longevity of devices were recorded.ResultsEight internal jugular pacemaker insertions were performed successfully in patients weighing between 10.9 kg and 29 kg. Five patients had Micra implantation via the right internal jugular vein, whereas 3 patients had insertion via the left internal jugular vein. No surgical cut-downs were performed. No venous complications occurred. Up to 3 years of follow-up were noted.ConclusionLeadless pacemaker implantation, via left or right internal jugular veins, is feasible without surgical cutdown in patients <30 kg     

Implantation of a Bi-Ventricular Pacing System in the Setting of Dextrocardia with Situs Inversus Totalis

Dextrocardia with situs inversus totalis is a rare disorder but is frequently associated with anomalous venous return. Pacemaker/Internal Cardioverter Defibrillator implantation in this population can be difficult given the difficult venous anatomy. This case illustrates how beforehand knowledge of the venous anatomy by cardiac MRI can facilitate device implantation.     

2021 PACES expert consensus statement on the indications and management of cardiovascular implantable electronic devices in pediatric patients: Executive summary

Guidelines for the implantation of cardiac implantable electronic devices (CIEDs) have evolved since publication of the initial ACC/AHA pacemaker guidelines in 1984 [1]. CIEDs have evolved to include novel forms of cardiac pacing, the development of implantable cardioverter defibrillators (ICDs) and the introduction of devices for long term monitoring of heart rhythm and other physiologic parameters. In view of the increasing complexity of both devices and patients, practice guidelines, by necessity, have become increasingly specific. In 2018, the ACC/AHA/HRS published Guidelines on the Evaluation and Management of Patients with Bradycardia and Cardiac Conduction Delay [2], which were specific recommendations for patients >18 years of age. This age-specific threshold was established in view of the differing indications for CIEDs in young patients as well as size-specific technology factors. Therefore, the following document was developed to update and further delineate indications for the use and management of CIEDs in pediatric patients, defined as ≤21 years of age, with recognition that there is often overlap in the care of patents between 18 and 21 years of age.This document is an abbreviated expert consensus statement (ECS) intended to focus primarily on the indications for CIEDs in the setting of specific disease/diagnostic categories. This document will also provide guidance regarding the management of lead systems and follow-up evaluation for pediatric patients with CIEDs. The recommendations are presented in an abbreviated modular format, with each section including the complete table of recommendations along with a brief synopsis of supportive text and select references to provide some context for the recommendations. This document is not intended to provide an exhaustive discussion of the basis for each of the recommendations, which are further addressed in the comprehensive PACES-CIED document [3], with further data easily accessible in electronic searches or textbooks.     

Mechanically induced electrical storm as a complication of cardiac resynchronization therapy: A case report

BackgroundCardiac resynchronization therapy (CRT) has been shown to improve both the functional status and mortality of heart failure patients with left bundle branch block. Multiple recent studies suggest several mechanisms for proarrhythmia associated with CRT device.Case summaryA 51-year-old male with symptomatic non-ischemic cardiomyopathy and no previous history of ventricular arrhythmias underwent placement of a biventricular cardioverter-defibrillator. The patient developed sustained monomorphic ventricular tachycardia (VT) soon after implantation. The VT recurred despite reprogramming to right ventricular only pacing. The electrical storm resolved only after a subsequent discharge from the defibrillator caused inadvertent dislodgement of the coronary sinus lead. No recurrent VT occurred throughout 10-years follow up after urgent coronary sinus lead revision.DiscussionWe describe the first reported case of mechanically induced electrical storm due to the physical presence of the CS lead in a patient with a new CRT-D device. It is important to recognize mechanical proarrhythmia as a potential mechanism of electrical storm, as it may be intractable to device reprogramming. Urgent coronary sinus lead revision should be considered. Further studies on this mechanism of proarrhythmia are needed.     

Permanent His Bundle Pacing: A programming and troubleshooting guide

Permanent His Bundle Pacing (HBP) has recently gained popularity. However, implanting physicians and those who perform the device checks must invest in additional education in order to accurately program these devices, identify changes in morphology and perform troubleshooting to help achieve the best outcomes for the patients. This paper reviews key aspects of HBP and provides the educational tools for successful HBP follow-up and troubleshooting.