Novel algorithms improve arrhythmia detection accuracy in insertable cardiac monitors.

Introduction: Insertable cardiac monitors (ICMs) are commonly used to diagnose cardiac arrhythmias. False detections in the latest ICM systems remain an issue, primarily due to inaccurate R-wave sensing. New discrimination algorithms were developed and tested to reduce false detections of atrial fibrillation (AF), pause, and tachycardia episodes in ICMs.

Integration of 3D nuclear imaging in 3D mapping system for ventricular tachycardia ablation in patients with implanted devices: Perfusion/voltage retrospective assessment of scar location.

Background: The identification of low-voltage proarrhythmic areas for catheter ablation of scar-mediated ventricular tachycardia (VT) remains challenging. Integration of myocardial perfusion imaging (single-photon emission computed tomography/computed tomography; SPECT/CT) and electroanatomical mapping (EAM) may improve delineation of the arrhythmogenic substrate.

Objective: To assess the feasibility of SPECT/CT image integration with voltage maps using the EnSite Precision system (Abbott) in patients undergoing scar-mediated VT ablation.

Changes in R-wave amplitude at implantation are associated with gender and orientation of insertable cardiac monitor: observations from the confirm Rx™ body posture and physical activity study.

Background: Insertable cardiac monitors (ICMs) are small subcutaneously implanted devices that detect changes in R-wave amplitudes (RWAs), effective in arrhythmia-monitoring. Although ICMs have proven to be immensely successful, electrical artefacts are frequent and can lead to misdiagnosis. Thus, there is a growing need to sustain and increase efficacy in detection rates by gaining insight into various patient-specific factors such as body postures and activities.

R-wave amplitude changes with posture and physical activity over time in an insertable cardiac monitor.

Background: Insertable cardiac monitors (ICMs) are accepted tools in cardiac arrhythmia management. Consistent R-wave amplitude (RWA) is essential for optimal detection.

Objectives: Assess RWAs with posture/activities at insertion and at 30 days.

Reducing the electrogram review burden imposed by insertable cardiac monitors.

Background: Insertable cardiac monitors (ICMs) are essential for ambulatory arrhythmia diagnosis. However, definitive diagnoses still require time-consuming, manual adjudication of electrograms (EGMs).

Objective: To evaluate the clinical impact of selecting only key EGMs for review.

Subcutaneouscardiac Rhythm Monitors: A Comprehensive Review.

Subcutaneous loop recorders (SCRMs) are subcutaneous electronic devices which have revolutionized the field of arrhythmia detection. They have become increasingly appealing due to advances such as miniaturization of device, longer battery life, bluetooth capabilities and relatively simple implantation technique without the need for complex surgical suites. They can be implanted in the office, patient bedside without the need to go to the operating room.

Effectiveness of SharpSense™ algorithms in reducing bradycardia and pause detection: real-world performance in Confirm Rx™ insertable cardiac monitor.

Purpose: SharpSense™ technology is an upgradable software enhancement introduced to the Abbott Confirm Rx™ insertable cardiac monitor (ICM). This study aims to characterize the real-world performance of SharpSense algorithms by comparing device detected pause and bradycardia episodes before and after the SharpSense upgrade.

Methods: Confirm Rx devices with at least 90 days monitoring each before and after SharpSense upgrade were included in the study.

Ventricular activation patterns during intrinsic conduction and right ventricular pacing in cardiac resynchronization therapy patients.

Background: Cardiac resynchronization therapy (CRT) involves stimulation of both right ventricle (RV) and left ventricle (LV). LV pacing from the sites of delayed electrical activation improves CRT response. The RV-LV conduction is typically measured in intrinsic rhythm.

Atrial natriuretic peptide accelerates onset and dynamics of ventricular fibrillation during hypokalemia in isolated rabbit hearts.

Background: Atrial natriuretic peptide (ANP), which is released by the heart in response to acute cardiac stretch, possesses cardiac electrophysiological properties that include modulation of ion channel function and repolarization. However, data regarding whether ANP can directly modulate electrical instability or arrhythmias are largely lacking.

Objective: This study sought to determine whether ANP modifies onset or electrophysiological characteristics of ventricular fibrillation (VF) induced by severe hypokalemia in an isolated heart model.

Electrical synchronization achieved by multipoint pacing combined with dynamic atrioventricular delay.

Purpose: Multipoint pacing (MPP) improves left ventricular (LV) electrical synchrony in cardiac resynchronization therapy (CRT). SyncAV automatically adjusts atrioventricular delay (AVD) according to intrinsic AV intervals and may further improve synchrony. Their combination has not been assessed.

Extending multipoint pacing CRT battery longevity by swapping left ventricular pulse configurations.

Purpose: Cardiac resynchronization therapy (CRT) with left ventricular (LV) MultiPoint™ pacing (MPP) has been shown to improve CRT response by pacing two LV sites (LV1, LV2). While an additional LV pacing site reduces battery longevity, this cost can be minimized by leveraging an existing device-based capture management algorithm (LVCap™ Confirm). The purpose of this study was to evaluate the MPP battery longevity improvement achieved by configuring LV pacing sites to properly leverage LVCap Confirm.

Non-paroxysmal atrial fibrillation mapping: characterization of the electrophysiological substrate using a novel integrated mapping technique.

Aims: Clinical outcomes after radiofrequency catheter ablation (RFCA) remain suboptimal in the treatment of non-paroxysmal atrial fibrillation (AF). Electrophysiological mapping may improve understanding of the underlying mechanisms. To describe the arrhythmia substrate in patients with persistent (Pers) and long-standing persistent (LSPers) AF, undergoing RFCA, using an integrated mechanism mapping technique.

Multipoint left ventricular pacing improves response to cardiac resynchronization therapy with and without pressure-volume loop optimization: comparison of the long-term efficacy of two different programming strategies.

Purpose: Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing (MultiPoint™ Pacing [MPP]) improves long-term LV reverse remodeling, though questions persist about how to program LV pacing vectors and delays. We evaluated if an empirical method of programming MPP vectors and delays between pacing pulses improved CRT response similar to pressure-volume loop (PVL) optimized MPP programming.

Methods: Patients undergoing CRT implant (Quadra Assura MP™ CRT-D and Quartet™ LV lead) received MPP with programmed settings optimized either by PVL measurements at implant (PVL-OPT group) or empirically determined by maximizing the spatial separation between the two cathodes and minimal delays between the three ventricular pacing pulses (MAX-SEP group).

Long-term reverse remodeling by cardiac resynchronization therapy with MultiPoint Pacing: A feasibility study of noninvasive hemodynamics-guided device programming.

Background: Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing (MultiPoint Pacing [MPP]) improves acute hemodynamics and chronic outcomes in comparison to conventional biventricular pacing (BiV), though MPP programming questions persist.

Objectives: In this multicenter feasibility study, we evaluated the feasibility of using noninvasive systolic blood pressure (SBP) to guide MPP programming and assessed the chronic 6-month echocardiographic CRT response.

Methods: Patients implanted with MPP-enabled CRT-defibrillator devices underwent noninvasive hemodynamic assessment (finger arterial pressure) during a pacing protocol that included atrial-only pacing and various BiV and MPP configurations.

Clinical Outcome of Electrophysiologically Guided Ablation for Nonparoxysmal Atrial Fibrillation Using a Novel Real-Time 3-Dimensional Mapping Technique: Results From a Prospective Randomized Trial.

Background: Clinical outcomes after ablation of persistent atrial fibrillation remain suboptimal. Identification of AF drivers using a novel integrated mapping technique may be crucial to ameliorate the clinical outcome.

Methods And Results: Persistent AF patients were prospectively enrolled to undergo high-density electrophysiological mapping to identify repetitive-regular activities (RRas) before modified circumferential pulmonary vein (PV) ablation.

Characterizing left ventricular mechanical and electrical activation in patients with normal and impaired systolic function using a non-fluoroscopic cardiovascular navigation system.

Purpose: Cardiac disease frequently has a degenerative effect on cardiac pump function and regional myocardial contraction. Therefore, an accurate assessment of regional wall motion is a measure of the extent and severity of the disease. We sought to further validate an intra-operative, sensor-based technology for measuring wall motion and strain by characterizing left ventricular (LV) mechanical and electrical activation patterns in patients with normal (NSF) and impaired systolic function (ISF).

Multipoint pacing improves peripheral hemodynamic response: Noninvasive assessment using radial artery tonometry.

Background: Multipoint left ventricular (LV) pacing (MultiPoint™ Pacing [MPP], Abbott, Sylmar, CA, USA) improves the response rate to cardiac resynchronization therapy (CRT). We evaluated the feasibility of noninvasive radial artery tonometry (RAT) to characterize arterial pressure morphology changes (pre-ejection period [PEP] and ejection duration [ED]) between conventional CRT and MPP pacing interventions.

Methods: Patients with a MPP-enabled CRT device (Quadra Assura MP™, Abbott) underwent noninvasive RAT assessment (SphygmoCor CVMS, AtCor Medical Inc.

Additional electrodes on the Quartet™ LV lead provide more programmable pacing options than bipolar and tripolar equivalents.

Aims: The aim of this study was to evaluate any benefits to the number of viable pacing vectors and maximal spatial coverage with quadripolar left ventricular (LV) leads when compared with tripolar and bipolar equivalents in patients receiving cardiac resynchronization therapy (CRT).

Methods And Results: A meta-analysis of five previously published clinical trials involving the Quartet™ LV lead (St Jude Medical, St Paul, MN, USA) was performed to evaluate the number of viable pacing vectors defined as capture thresholds ≤2.5 V and no phrenic nerve stimulation and maximal spatial coverage of viable vectors in CRT patients at pre-discharge (n = 370) and first follow-up (n = 355).

Subclavian access using a three-dimensional electromagnetic cardiovascular navigation system: novel approach to access the venous system during device implant procedures.

We report a case in which a novel three-dimensional (3D) electromagnetic cardiovascular navigation system (MediGude™, St. Jude Medical, St. Paul, MN, USA) was used to create a 3D reconstruction of the axillary vein and its anatomic course to guide its successful puncture and cannulation.

Mapping-guided characterization of mechanical and electrical activation patterns in patients with normal systolic function using a sensor-based tracking technology.

Aims: In times of evolving cardiac resynchronization therapy, intra-procedural characterization of left ventricular (LV) mechanical activation patterns is desired but technically challenging with currently available technologies. In patients with normal systolic function, we evaluated the feasibility of characterizing LV wall motion using a novel sensor-based, real-time tracking technology.

Methods And Results: Ten patients underwent simultaneous motion and electrical mapping of the LV endocardium during sinus rhythm using electroanatomical mapping and navigational systems (EnSite™ NavX™ and MediGuide™, SJM).

Three-Dimensional Cardiac Mapping Characterizes Ventricular Contractile Patterns during Cardiac Resynchronization Therapy Implant: A Feasibility Study.

Background: Electroanatomic mapping systems track the position of electrodes in the heart. We assessed the feasibility of characterizing left ventricular (LV) performance during cardiac resynchronization therapy (CRT) implant utilizing an electroanatomic mapping system to track the motion of CRT lead electrodes, thus deriving ventricular contractility surrogates.

Methods: During CRT implant, atrial, right ventricular (RV), and LV leads were connected to the EnSite NavX™ mapping system (St.

Insights into new-onset atrial fibrillation following open heart surgery and implications for type II atrial flutter.

Aims: Postoperative atrial fibrillation (POAF), new-onset AF after open heart surgery (OHS), is thought to be related to pericarditis. Based on AF studies in the canine sterile pericarditis model, we hypothesized that POAF in patients after OHS may be associated with a rapid, regular rhythm in the left atrium (LA), suggestive of an LA driver maintaining AF. The aim of this study was to test the hypothesis that in patients with POAF, atrial electrograms (AEGs) recorded from at least one of the two carefully selected LA sites would manifest a rapid, regular rhythm with AEGs of short cycle length (CL) and constant morphology, but a selected right atrial (RA) site would manifest AEGs with irregular CLs and variable morphology.

Improving cardiac resynchronization therapy response with multipoint left ventricular pacing: Twelve-month follow-up study.

Background: Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing (MultiPoint™ Pacing [MPP], St. Jude Medical) improves acute LV function and LV reverse remodeling at 3 months.

Objective: The purpose of this study was to test the hypothesis that MPP can also improve LV function at 12 months.

Multipoint left ventricular pacing in a single coronary sinus branch improves mid-term echocardiographic and clinical response to cardiac resynchronization therapy.

Introduction: Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing in a single coronary sinus branch improves acute LV function. We hypothesized that multipoint pacing (MPP) can improve midterm echocardiographic and clinical response compared with conventional CRT.

Methods And Results: Consecutive patients receiving a CRT implant (Unify Quadra MP™ or Quadra Assura MP™ CRT-D and Quartet™ LV lead, St.