Edward Karst

Acute haemodynamic comparison of multisite and biventricular pacing with a quadripolar left ventricular lead.

AIMS Pacing from multiple sites in the left ventricle (LV) may bring about further resynchronization of the diseased heart compared with biventricular (BiV) pacing. We compared acute haemodynamic response (LV dP/dtmax) of multisite and BiV pacing using a quadripolar LV lead. METHODS AND RESULTS In 21 patients receiving cardiac resynchronization therapy, a quadripolar LV lead and conventional right atrial and ventricular leads were connected to an external pacing system. A guidewire pressure sensor was placed in the LV for continuous dP/dt measurement. Four multisite pacing configurations were tested three times each and compared with BiV pacing using the distal LV electrode. Nineteen patients had useable haemodynamic data. Median increase in LV dP/dtmax with BiV vs. atrial-only pacing was 8.2% (interquartile range 2.3%, 15.7%). With multisite pacing using distal and proximal LV electrodes, median increase in LV dP/dtmax was 10.2% compared with atrial-only pacing (interquartile range 6.1%, 25.6%). In 16 of 19 patients (84%), two or more of the four multisite pacing configurations increased LV dP/dtmax compared with BiV pacing. Overall, 72% of all tested configurations of multisite pacing produced greater LV dP/dtmax than obtained with BiV pacing. Pacing from most distal and proximal electrodes was the most common optimal configuration, superior to BiV pacing in 74% of patients. CONCLUSION In the majority of patients, multisite pacing improved acute systolic function further compared with BiV pacing. Pacing with the most distal and proximal electrodes of the quadripolar LV lead most commonly yielded greatest LV dP/dtmax.

Clinical Implications of Brief Device-Detected Atrial Tachyarrhythmias in a Cardiac Rhythm Management Device Population: Results from the Registry of Atrial Tachycardia and Atrial Fibrillation Episodes

Background: The RATE Registry (Registry of Atrial Tachycardia and Atrial Fibrillation Episodes) is a prospective, outcomes-oriented registry designed to document the prevalence of atrial tachycardia and/or fibrillation (AT/AF) of any duration in patients with pacemakers and implantable cardioverter defibrillators (ICDs) and evaluate associations between rigorously adjudicated AT/AF and predefined clinical events, including stroke. The appropriate clinical response to brief episodes of AT/AF remains unclear. Methods: Rigorously adjudicated electrogram (EGM) data were correlated with adjudicated clinical events with logistic regression and Cox models. Long episodes of AT/AF were defined as episodes in which the onset and/or offset of AT/AF was not present within a single EGM recording. Short episodes of AT/AF were defined as episodes in which both the onset and offset of AT/AF were present within a single EGM recording. Results: We enrolled 5379 patients with pacemakers (N=3141) or ICDs (N=2238) at 225 US sites (median follow-up 22.9 months). There were 359 deaths. There were 478 hospitalizations among 342 patients for clinical events. We adjudicated 37 531 EGMs; 50% of patients had at least one episode of AT/AF. Patients with clinical events were more likely than those without to have long AT/AF (31.9% vs. 22.1% for pacemaker patients and 28.7% vs. 20.2% for ICD patients; P<0.05 for both groups). Only short episodes of AT/AF were documented in 9% of pacemaker patients and 16% of ICD patients. Patients with clinical events were no more likely than those without to have short AT/AF (5.1% vs. 7.9% for pacemaker patients and 11.5% vs. 10.4% for ICD patients; P=0.21 and 0.66, respectively). Conclusions: In the RATE Registry, rigorously adjudicated short episodes of AT/AF, as defined, were not associated with increased risk of clinical events compared with patients without documented AT/AF. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00837798.

Pacing electrode selection in a quadripolar left heart lead determines presence or absence of phrenic nerve stimulation

A 60-year-old ischaemic patient presented for routine cardiac resynchronization therapy (CRT)-D implantation. An investigational quadripolar left ventricular lead was placed in the posterolateral vein. Phrenic nerve stimulation (PNS) was observed, but it occurred during pacing from only one of the four electrodes. A lead with multiple pacing electrodes is a potential alternative to physical adjustment of the lead or discontinuing CRT when PNS occurs.

Longer Delay From Chronic Pain to Spinal Cord Stimulation Results in Higher Healthcare Resource Utilization.

A shorter delay time from chronic pain diagnosis to spinal cord stimulation (SCS) implantation may make it more likely to achieve lasting therapeutic efficacy with SCS. The objective of this analysis was to determine the impact of pain‐to‐SCS time on patients’ post‐implant healthcare resource utilization (HCRU).

Design of an acute dP/dt hemodynamic measurement protocol to isolate cardiac effect of pacing.

BACKGROUND Invasively measured maximum increase in left ventricular pressure (LV dP/dtmax) has been used to assess biventricular (BiV) pacing. We quantified extracardiac factors contributing to its variability, and developed a protocol to minimize these effects in an acute pacing experiment. METHODS AND RESULTS Continuous pressure was recorded by a guidewire sensor placed in the LV. Four to six test pacing interventions were performed, each repeated 3 times and followed by a baseline pacing configuration. Maximum increase in LV dP/dtmax from any measurement of BiV pacing was median 20.3% in 25 patients, compared with BiV pacing off. When directly comparing sequential measurements with BiV pacing on and off, median increase was 7.4%. Noncardiac sources of modulation included respiratory variation (6.4%), drift from first to last baseline measurement (5.0%), and discrepancy among repeated recordings of the same pacing intervention (3.3%). Comparing test interventions to interleaved baseline measurements reduced discrepancy among recordings to 2.1%; P < .001. CONCLUSIONS With repeated measurements of baseline state, and by comparing test interventions only to baseline measurements performed before and after, it is possible to minimize extracardiac factors and focus on the effects of test pacing interventions.

Proceedings of the second annual deep brain stimulation think tank: What's in the pipeline

The proceedings of the 2nd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, and computational work on DBS for the treatment of neurological and neuropsychiatric disease and represent the insights of a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers and members of industry. Presentations and discussions covered a broad range of topics, including advocacy for DBS, improving clinical outcomes, innovations in computational models of DBS, understanding of the neurophysiology of Parkinsons disease (PD) and Tourette syndrome (TS) and evolving sensor and device technologies.

Pacemaker-induced transient asynchrony suppresses heart failure progression.

Transient asynchrony induced by an implanted pacemaker improves pathobiology of heart failure in large animals. Disruptive technology Healthy and the majority of failing hearts beat synchronously. However, some hearts contract with poor coordination and if they are weak, this worsens clinical outcomes. Pacemakers used to reset a heart’s rhythm can also change the synchrony of contraction, making it better or worse, and current therapy called resynchronization makes it better. Perhaps counterintuitively, Kirk et al. demonstrate that using a pacemaker to purposely induce dyssynchrony—but only for part of each day—makes the synchronous failing heart better. In their process, pacemaker-induced transient asynchrony (PITA), the heart’s right ventricle is paced to induce a 6-hour period of dyssynchrony each day, followed by atrial pacing to resynchronize the heart for the remaining 18 hours. In dogs with heart failure, PITA halted chamber dilation and negative remodeling of the heart tissue, improved cellular signaling and force generation, and resulted in normal muscle fiber structure and function, similar to healthy controls. PITA may help the majority of patients with heart failure who have synchronous contraction and thus are not treated with standard resynchronization pacemakers. Uncoordinated contraction from electromechanical delay worsens heart failure pathophysiology and prognosis, but restoring coordination with biventricular pacing, known as cardiac resynchronization therapy (CRT), improves both. However, not every patient qualifies for CRT. We show that heart failure with synchronous contraction is improved by inducing dyssynchrony for 6 hours daily by right ventricular pacing using an intracardiac pacing device, in a process we call pacemaker-induced transient asynchrony (PITA). In dogs with heart failure induced by 6 weeks of atrial tachypacing, PITA (starting on week 3) suppressed progressive cardiac dilation as well as chamber and myocyte dysfunction. PITA enhanced β-adrenergic responsiveness in vivo and normalized it in myocytes. Myofilament calcium response declined in dogs with synchronous heart failure, which was accompanied by sarcomere disarray and generation of myofibers with severely reduced function, and these changes were absent in PITA-treated hearts. The benefits of PITA were not replicated when the same number of right ventricular paced beats was randomly distributed throughout the day, indicating that continuity of dyssynchrony exposure is necessary to trigger the beneficial biological response upon resynchronization. These results suggest that PITA could bring the benefits of CRT to the many heart failure patients with synchronous contraction who are not CRT candidates.

Therapy-Related Explants After Spinal Cord Stimulation: Results of an International Retrospective Chart Review Study

Clinical trials of spinal cord stimulation (SCS) have largely focused on conversion from trial to permanent SCS and the first years after implant. This study evaluates the association of type of SCS and patient characteristics with longer‐term therapy‐related explants.

Association of Opioid Usage with Spinal Cord Stimulation Outcomes

Study Design Observational study using insurance claims. Objective To quantify opioid usage leading up to spinal cord stimulation (SCS) and the potential impact on outcomes of SCS. Setting SCS is an interventional therapy that often follows opioid usage in the care continuum for chronic pain. Methods This study identified SCS patients using the Truven Health MarketScan databases from January 2010 to December 2014. The index event was the first occurrence of a permanent SCS implant. Indicators of opioid usage at implant were daily morphine equivalent dose (MED), number of unique pain drug classes, and diagnosis code for opioid abuse. System explant was used as a measure of ineffective SCS therapy. Multivariate logistic regression was used to analyze the effect of pre-implant medications on explants. Results A total of 5,476 patients (56 ± 14 years; 60% female) were included. SCS system removal occurred in 390 patients (7.1%) in the year after implant. Number of drug classes (odds ratio [OR] = 1.11, P = 0.007) and MED level (5-90 vs < 5 mg/d: OR = 1.32, P = 0.043; ≥90 vs < 5 mg/d: OR = 1.57, P = 0.005) were independently predictive of system explant. Over the year before implant, MED increased in 54% (stayed the same in 21%, decreased in 25%) of patients who continued with SCS and increased in 53% (stayed the same in 20%, decreased in 27%) of explant patients (P = 0.772). Over the year after implant, significantly more patients with continued SCS had an MED decrease (47%) or stayed the same (23%) than before (P < 0.001). Conclusions Chronic pain patients receive escalating opioid dosage prior to SCS implant, and high-dose opioid usage is associated with an increased risk of explant. Neuromodulation can stabilize or decrease opioid usage. Earlier consideration of SCS before escalated opioid usage has the potential to improve outcomes in complex chronic pain.

Clinical Paresthesia Atlas Illustrates Likelihood of Coverage Based on Spinal Cord Stimulator Electrode Location

Concordant paresthesia coverage is an independent predictor of pain relief following spinal cord stimulation (SCS). Using aggregate data, our objective is to produce a map of paresthesia coverage as a function of electrode location in SCS.