Pacing Electrodes Research Articles

Inhibition of Sodium Glucose Cotransporter-2 Mitigates Heart Failure Progression in Obesity

Recent clinical outcome studies (EMPA-REG and CANVAS) have demonstrated that a novel class of anti-hyperglycemic agents, which act by inhibiting the sodium-glucose cotransporter-2 (SGLT2i), reduce the risk of hospitalization for heart failure in subjects with type 2 diabetes mellitus. However, the cardiovascular effects of SGLT2i in heart failure are poorly understood. The purpose of the present study was to examine the hypothesis that preventative SGLT2i administration attenuates the progression of heart failure in the setting of obesity. Ossabaw swine were fed a high fat/high carbohydrate diet for 3 months and chronically instrumented with a telemetry system and a pacing electrode. Following recovery from surgery, animals were randomized to treatment groups (control vs. canagliflozin (300 mg orally per day)). Canagliflozin treatment began immediately prior to initiation of high rate pacing and was continued until terminal procedure was performed. Animals in both groups (control, n = 5 and SGLT2i, n = 5) were paced at a heart rate of 182 beats/min for ∼3-4 weeks prior to terminal procedure at which time measurements were obtained. Body weights were similar between control (62 ± 4 kg) and SGLT2i treated swine (60 ± 5 kg) (P = 0.77) Chronic high rate pacing augmented left ventricular (LV) end-diastolic pressure to ∼31 ± 3 mmHg in control swine (LV end-diastolic pressure in normal swine typically

Assessment of myocardial electrical dissynchrony by noninvasive activation mapping and its role in achieving the success of cardiac resynchronization

To assess and to compare the ventricular myocardium activation patern obtained by non-invasive epi- and endocardial mapping (NIEEM), as well as electrocardiographic (ECG) variants of lef bundle branch block (LBBB) and to estimate the value of these data for the success of cardiac resynchronization therapy (CRT). Te study included 23 patients (mean age 59,6±9,9 years) with LBBB, QRS duration ≥ 130 ms, lef ventricular ejection fraction (LVEF) ≤ 35%, heart failure (HF) NYHA II-IV despite optimal pharmacological therapy during 3 month. All patients had undergone CRT-D implantation. Depending on presence or absence of LBBB ECG-criteria, proposed by Strauss D.G. et. al, patients were divided into 2 groups: 1group - strict LBBB, proposed by Strauss D.G. et. al. (n=14) and 2 group - other ECG morphologies of LBBB (n=9). NIEEM by the Amycard 01C system with an analysis of epi- and endocardial ventricular electrical activation was performed in all patients and 5 healthy volunteers (mean age 29±1,0years). Response to CRT was estimated by echo and was defned as decrease in lef ventricular (LV) end-systolic volume by > 15% afer 6 months of follow-up. LBBB ECG-criteria, proposed by Strauss D.G. et. al, was detected in 14 patients (61% of all included). According to the results of NIEEM, these patients had more pronounced ventricular electrical uncoupling (VEU) (р=0,002). Most ofen the line of block was detected in the anteroseptal or posterolateral region of the LV. Te zone of late LV activation, which is the most optimal position for the LV pacing electrode, was located in the basal and middle segments of the lateral and posterior walls. Afer 6 months of CRT 15 patients (65%) were included in the "response" group, the remaining 8 patients (35%) formed the "non-response" group according to echo criteria. In the "response" group the morphology of the QRS complex more frequently met the criteria, proposed by Strauss D.G. et al, than other ECG variants of LBBB (12 vs. 3 respectively, p = 0.023). Initially, VEU was more pronounced in the "response" group (VEU 55 [51, 64] ms in the "response" group vs 22 [8, 38] ms in the "non-response" group).Сonclusions. LBBB ECG criteria, proposed by Strauss D.G., identify patients with delayed transseptal interventricular conduction due to complete LBBB, what is a good target for CPT. Identifcation of individual ventricular activation properties may help to reveal responders to CRT in patients with LBBB.

Conceptual Intra-Cardiac Electrode Configurations That Facilitate Directional Cardiac Stimulation for Optimal Electrotherapy.

Electrotherapy remains the most effective direct therapy against lethal cardiac arrhythmias. When an arrhythmic event is sensed, either strong electric shocks or controlled rapid pacing is automatically applied directly to the heart via an implanted cardioverter defibrillator (ICDs). Despite their success, ICDs remain a highly non-optimal therapy: the strong shocks required for defibrillation cause significant extra-cardiac stimulation, resulting in pain and long-term tissue damage, and can also limit battery life. When used in anti-tachycardia pacing mode, ICDs are also often ineffective, as the pacing electrode can be far away from the centre of the arrhythmia, making it hard for the paced wave to interrupt and terminate it. In this paper, we present two conceptual intra-cardiac directional electrode configurations in silico based on novel arrangements of pairs of positive-negative electrodes. Both configurations have the potential to cause preferential excitation on specific regions of the heart. We demonstrate how the properties of the induced field varies spatially around the electrodes and how it depends upon the specific arrangements of dipole electrode pairs. The results show that when tested within anatomically-realistic rabbit ventricular models, both electrode configurations produce strong virtual electrodes on the targeted endocardial surfaces, with weaker virtual electrodes produced elsewhere. The proposed electrode configurations may facilitate targeted far-field anti-tachycardia pacing and/or defibrillation, which may be useful in cases where conventional anti-tachycardia pacing fails. In addition, the conceptual electrode designs intrinsically confine the electric field to the immediate vicinity of the electrodes, and may, thus, minimize pain due to unnecessary extra-cardiac stimulation.

Reduction of QRS amplitude correlates with decrease in left-ventricular pre-ejection time after cardiac resynchronisation therapy

Left ventricular pre-ejection time (LVPET) is associated with myocardial efficiency. LVPET increases in patients with heart failure and decreases after cardiac resynchronisation therapy (CRT) with variation according to pacing site. The objective of this study was to evaluate the relationship between electrocardiogram (ECG) parameters and LVPET in patients with CRT. It was an observational, prospective, and monocentric study. From May 2017 to October 2017, all patients who underwent CRT with left quadripolar lead in Rouen University Hospital were included. LVPET was evaluated by echocardiography and defined as the time between the beginning of the QRS and the beginning of pulsed Doppler signal positioned in left ventricular outflow tract in apical view. The following parameters on 12-leads ECG were assessed: QRS width in V3, sum of QRS amplitude in all lead. Measures were performed during bi-ventricular pacing (at each pacing electrode of the quadripolar lead called D1, M2, M3, P4, for distal to proximal ones), left-ventricular pacing alone, right-ventricular pacing alone, and spontaneous rhythm. Partial correlation test was used. Seventeen patients were included. In each patient, LVPET was correlated with QRS width ( P = 0.02, R = 0.194) and QRS amplitude ( P < 0.001, R = 0.427) ( Fig. 1 ). It was observed that the lower the LVPET, the lower the QRS amplitude and the narrower the QRS width. In each patient, mean variation of QRS width was equal to 64.7 ± 29.4%, mean variation of LVPET was equal to 37.1 ± 16.4% and mean variation of QRS amplitude was equal to 53.2 ± 27.4%. QRS width, but also QRS amplitude varies according to the pacing site after CRT and are correlated with left ventricular pre-ejection time. These ECG parameters could be helpful to optimize CRT.

Dynamic programming of atrioventricular delay improves electrical synchrony in a multicenter cardiac resynchronization therapy study

Patient-specific programming of cardiac resynchronization therapy (CRT) is often neglected, despite significant nonresponse rates. The device-based SyncAV CRT algorithm dynamically adjusts atrioventricular delays to the intrinsic AV interval, reduced by a programmable offset, to accommodate each patient's changing needs. The purpose of this study was to evaluate the acute effect of biventricular (BiV) pacing enhanced by SyncAV on electrical synchrony in a broad patient population. Patients with existing CRT implants were prospectively evaluated at 5 international centers. Blinded 12-lead electrocardiographic QRS duration (QRSd) measurements were used to compare intrinsic conduction with nominal BiV pacing, BiV + SyncAV (default 50 ms offset), and BiV + SyncAV (optimized, patient-specific offset). BiV configurations were tested twice using the latest activating and earliest activating left ventricular (LV) electrodes as cathodes. Ninety patients (mean age 67.1 ± 9.5 years; 67 (74%) men; 55 (63%) with left bundle branch block; 37 (43%) with ischemic cardiomyopathy; LV ejection fraction 32% ± 9%) with intact atrioventricular conduction (PR interval 195 ± 45 ms) were enrolled. With BiV pacing from the latest activating LV electrode, the intrinsic QRSd of 155 ± 29 ms was reduced by 9% ± 20% to 138 ± 27 ms using traditional BiV pacing and by 13% ± 14% to 133 ± 25 ms using BiV + SyncAV (50 ms offset). The maximal QRSd reduction by 20% ± 10% to 123 ± 22 ms was achieved by BiV + SyncAV with an optimized offset. Similar QRSd reductions were observed with BiV pacing from the earliest activating LV electrode across all settings. Of all baseline characteristics, intrinsic QRSd was the only significant predictor of QRSd reduction magnitude. SyncAV improved acute electrical synchrony beyond conventional CRT, particularly with patient-specific optimization. The degree of synchrony restored was contingent on intrinsic QRSd, but not limited by other baseline characteristics or by the LV pacing electrode used.

Effect of chronic exercise on myocardial electrophysiological heterogeneity and stability. Role of intrinsic cholinergic neurons: A study in the isolated rabbit heart.

A study has been made of the effect of chronic exercise on myocardial electrophysiological heterogeneity and stability, as well as of the role of cholinergic neurons in these changes. Determinations in hearts from untrained and trained rabbits on a treadmill were performed. The hearts were isolated and perfused. A pacing electrode and a recording multielectrode were located in the left ventricle. The parameters determined during induced VF, before and after atropine (1μM), were: fibrillatory cycle length (VV), ventricular functional refractory period (FRPVF), normalized energy (NE) of the fibrillatory signal and its coefficient of variation (CV), and electrical ventricular activation complexity, as an approach to myocardial heterogeneity and stability. The VV interval was longer in the trained group than in the control group both prior to atropine (78±10 vs. 68±10 ms) and after atropine (76±8 vs. 67±10 ms). Likewise, FRPVF was longer in the trained group than in the control group both prior to and after atropine (53±8 vs. 42±7 ms and 50±6 vs. 40±6 ms, respectively), and atropine did not modify FRPVF. The CV of FRPVF was lower in the trained group than in the control group prior to atropine (12.5±1.5% vs. 15.1±3.8%) and, decreased after atropine (15.1±3.8% vs. 12.2±2.4%) in the control group. The trained group showed higher NE values before (0.40±0.04 vs. 0.36±0.05) and after atropine (0.37±0.04 vs. 0.34±0.06; p = 0.08). Training decreased the CV of NE both before (23.3±2% vs. 25.2±4%; p = 0.08) and after parasympathetic blockade (22.6±1% vs. 26.1±5%). Cholinergic blockade did not modify these parameters within the control and trained groups. Activation complexity was lower in the trained than in the control animals before atropine (34±8 vs. 41±5), and increased after atropine in the control group (41±5 vs. 48±9, respectively). Thus, training decreases the intrinsic heterogeneity of the myocardium, increases electrophysiological stability, and prevents some modifications due to muscarinic block.

Localization of Left Ventricular Lead Electrodes in Relation to Myocardial Scar in Patients Undergoing Cardiac Resynchronization Therapy.

BackgroundThe efficacy of cardiac resynchronization therapy may be reduced in the event of pacing within myocardial fibrosis. We aimed to develop a method to determine the anatomical relationships between the left ventricular (LV) lead and myocardial fibrosis.Methods and ResultsIn consecutive patients indicated for cardiac resynchronization therapy, cardiovascular magnetic resonance imaging with late gadolinium enhancement assessment was performed before implantation. After implantation, an injected computed tomography scanner (CT scan) was performed. The 2 imaging techniques were fused to assess the LV lead position relative to myocardial scar. A total of 68 patients were included. Myocardial scar was found in 29 (43%) and was localized in lateral segments in 14 (21%). Scar was significantly associated with male sex, ischemic cardiomyopathy, a Selvester score adapted to left bundle branch block (LBBB Selvester), and Selvester criteria for localizing lateral fibrosis (V2 S/S′ ratio). Image fusion was feasible in all patients. Position within myocardial scar was confirmed for 6 electrodes in 3 patients. Prolonged QRS duration during LV pacing ≥139% predicted electrode positioning within scar tissue (sensitivity, 83%; specificity, 91%; P=0.002).ConclusionsIn cardiac resynchronization therapy patients, fusion between preimplantation cardiovascular magnetic resonance and a postimplantation injected computed tomography scan is a feasible technique. Prolongation of the QRS duration during LV pacing predicts pacing within myocardial scar. Accurate location of LV lead pacing electrodes on the epicardial surface relative to myocardial scar, either by imaging or ECG analyses, may help improve cardiac resynchronization therapy response in selected patients.

Clinical presentation of ventricular-Hisian and ventricular-nodal accessory pathways

Narrow QRS tachycardia or premature beat with bystander atrial activation or ventricular-atrial dissociation is an unusual arrhythmia that can present diagnostic and therapeutic challenges. When ventricular-atrial conduction is robust, these arrhythmias can be difficult to distinguish from atrioventricular nodal reentry. The purpose of this study was to describe the electrophysiology characteristics, diagnostic maneuvers, and treatment of these types of arrhythmias in a series of 7 cases. Standard multipolar recording and pacing electrodes were used during electrophysiology studies. Catheter ablation was performed using radiofrequency or cryoenergy. During electrophysiology studies, ventricular-nodal or ventricular-Hisian conducting pathways were demonstrated to be responsible for the arrhythmias in all 7 cases. Successful ablation of these pathways using radiofrequency energy was accomplished in 6 of the 7 cases. Ventricular-Hisian and ventricular-nodal associated tachyarrhythmias should be distinguished from typical forms of atrioventricular nodal reentrant tachycardia. Catheter ablation of these pathways can be successfully accomplished using mapping techniques described in our report.

Acute and Long-term Performance of a Quadripolar Left Ventricular Lead in a Real-World Clinical Setting: Initial Results from the Quadripolar Post-Approval Study

Introduction The Quartet™ 1458Q left ventricular (LV) lead with a quadripolar CRT-D provides vector selection from four pacing electrodes resulting in 10 LV lead pacing configurations. Purpose: The Quadripolar Post-Approval Study is a prospective, multi-center study to assess acute and chronic performance of the Quartet 1458Q LV lead in patients indicated for cardiac resynchronization therapy (CRT). Methods Implanted subjects are followed for 60 months post implant. LV pacing capture threshold (PCT) and impedance values of final programed vectors are measured at each visit. Results Of 1,970 subjects enrolled (mean age 69 ± 11 years; 74 % men), 1,915 (97.2%) were successfully implanted. Mean follow-up time for all implanted subjects is 3.2 + 1.7 years. The LV lead was implanted in a lateral location in 47.6% (923/1970) of subjects. Mean PCT of the programmed vectors is 1.33 ± 0.93 V while mean impedance is 743.4 ± 282.8 Ω. Mean PCT and impedance measurements of the final programmed vectors at each follow-up visit are shown below. All 10 vectors have been used in at least one subject. Subjects with a vector change between baseline and 12 months (46%) account for 79.9% of all vector changes. A majority of changes (14.1%) have occurred from Vector 1 (bipolar configuration) to Vectors 3 and 5 (unipolar configurations). Reasons for vector programming are optimal capture threshold (79.7%), site of latest activation from CRT toolkit (5.3%) and no phrenic nerve stimulation (PNS) (4.3%). Estimated survival probability for LV lead-related complications at 60 months is 95.15% with 95% CI (93.87%, 96.17%). A total of 89 PNS adverse events have been reported in 71 subjects (3.7%), with 79.8% (71/89) resolved by device re-programing. There are 57 LV lead dislodgements in 54 subjects (2.8%). Conclusion The Quartet™ 1458Q LV lead has a high implant success rate, stable PCT and impedance across vectors over time with a low incidence of PNS. These results demonstrate the Quartet LV lead is reliable in delivering CRT using multiple pacing vectors providing physicians with a non-invasive option to meet the changing lead/patient interface without compromising electrical performance.

Feasibility of concomitant vacuum-assisted removal of lead-related vegetations and cardiac implantable electronic device extraction.

Cardiac implantable electronic device (CIED) infections associated with large, mobile vegetation adds to the complexity of lead extraction and is associated with significant patient morbidity and mortality. To show the feasibility of concomitant cardiovascular implantable electronic device extraction and vacuum-assisted removal of lead-related vegetations. This is a single-center retrospective case series of consecutive patients with persistent bacteremia, sepsis, or endocarditis despite medical therapy who have vegetations >2cm and subsequently underwent immediate CIED lead extraction after debulking with vacuum-assisted suction. Eight patients underwent successful removal of 17 leads immediately after debulking of vegetations with vacuum-assisted device suction. Debulking procedure was not successful in 1 patient due to inability to direct the vacuum suction device into proper position. There were no intraprocedure complications related to the vacuum-assisted debulking. One patient required open sternotomy for tear of the coronary sinus ostium related to extraction of a left ventricular pacing electrode. There was no mortality within 30 days of the procedure. Based upon these clinical results, it is feasible for patients with infected CIED systems that have large right-sided vegetations to undergo vacuum-assisted debulking then immediately followed by percutaneous CIED removal in whom surgical removal is considered high risk.

Percutaneousepicardial pacing using a novel transverse sinus device.

Transvenous lead implantation has multiple drawbacks and complications that can be overcome by epicardial lead placement. We aimed to design percutaneously implanted epicardial leads that are anchored through the transverse sinus (TS). We designed a novel multielectrode pacing device with four bipole electrode pairs. The device is advanced through the TS, with both ends externalized out of the pericardium. We tested the prototype in one proof-of-concept and 5 additional acute canine experiments. The TS device recorded ventricular and atrial electrograms. The median amplitude of near-field ventricular electrograms was 3.3mA (IQR 2.0-4.3) and of near-field atrial electrograms was 2.1mA (IQR 1.3-2.2). The median ventricular threshold (N=30) was 1.1mA (IQR 0.7-3.1) at a median pulse width of 0.5ms (IQR 0.5-0.5). The median atrial threshold (N=10) was 2.4mA (IQR 1.1-7.8) at a median pulse width of 0.5ms (IQR 0.5-0.9). Right and left ventricular and atrial pacing morphologies were noted while pacing electrodes adjacent to these chambers. Simultaneous left (LV) and right ventricular (RV) pacing showed reduction in QRS duration from 116ms (RV) and 105ms (LV) to 91ms. On necropsy, the device was located in the TS in all animals. There were TS abrasions in one animal, and no other acute complications. This study highlights a novel approach to epicardial pacing harnessing the unique anatomy of the transverse sinus as an anchoring point. Placement of this novel transverse sinus device was safe and feasible, with acceptable atrial and ventricular thresholds.

Long-term electrical performance of Attain Performa quadripolar left ventricular leads with all steroid-eluting electrodes: Results from a large worldwide clinical trial.

Steroid-eluting (SE) electrodes suppress local inflammation and lower pacing capture thresholds (PCT); however, their effectiveness on quadripolar left ventricular (LV) leads in the cardiac vein is not fully studied. We evaluated the effectiveness of SE on all four LV pacing electrodes in human subjects enrolled in the Medtronic Attain® Performa™ quadripolar LV lead study. A total of 1,097 subjects were included in this evaluation. At each follow-up visit (1, 3, 6, and 12 months), LV PCT and pacing impedance were measured using either manual or automated testing methods. Summary statistics for PCT and impedance values were obtained for implant and each scheduled follow-up visit for all lead models. Average extended bipolar (LV electrode to right ventricular Coil) PCTs for the four LV SE pacing electrodes (LV1, LV2, LV3, and LV4) on the three shapes of the quadripolar LV leads were 1.06 ± 0.97 V, 1.38 ± 1.26 V, 1.51 ± 1.33 V, and 2.25 ± 1.63 V, respectively, at 0.5-ms pulse width. PCTs remained low and stable throughout the 12-month follow-up period. This clinical trial demonstrated that SE on all LV pacing electrodes is associated with low and stable PCTs for all quadripolar LV lead electrodes, resulting in multiple viable vectors for LV pacing. The large number of available vectors facilitates basal pacing, avoidance of PNS, and potentially prolongs generator longevity due to lower PCTs.

Evaluation of the safety of MRI scans in patients undergoing dual-chamber pacemaker implantation.

The safety of magnetic resonance imaging (MRI) scans in patients undergoing dual-chamber pacemaker (Medtronic's EnRhythm MRI SureScan IPG (implantable pulse generator) and CapSureFix MRI pacing electrodes) implantation were evaluated. A total of 86 patients undergoing this pacemaker implantation who were admitted to Huanggang Hospital from June 2006 to March 2017 were continuously selected. On average 6.8±2.3 months after the implantation, the first MRI scan was conducted. The mean scan time was 2.2±0.9 and mean duration was 45.6±12.3 min; mean follow-up visit period was 40.5±15.6 months, and after follow-up, all the abnormal symptoms of patients and pacemaker abnormalities after scans were recorded. Causes of receiving MRI scans included neurological diseases (27%), spinal diseases (14%), cancers (26%), joint injuries (25%) and visceral systems (8%). A total of 12 cases (14.0%) showed significant discomfort symptoms, 10 cases (11.6%) showed pacemaker abnormalities, and the incidence rate was 25.6%. Multivariate logistic regression analysis showed that the basic types of cardiovascular diseases, dependence on pacemakers, duration of education, pacing threshold, impedance and MRI scan time were related to the occurrence of adverse scan results (p<0.05). In conclusion, MRI scans show that MRI-compatible dual-chamber pacemaker was relatively safe.

Guidance for Optimal Site Selection of a Leadless Left Ventricular Endocardial Electrode Improves Acute Hemodynamic Response and Chronic Remodeling.

This study hypothesized that guided implants, in which the optimal left ventricular endocardial (LVENDO) pacing location was identified and targeted, would improve acute markers of contractility and chronic markers of cardiac resynchronization (CRT) response. Biventricular endocardial (BiVENDO) pacing may offer a potential benefit over standard CRT; however, the optimal LVENDO pacing site is highly variable. Indiscriminately delivered BiVENDO pacing is associated with a reverse remodeling response rate of between 40% and 60%. Registry of centers implanting a wireless, LVENDO pacing system (WiSE-CRT System, EBR Systems, Sunnyvale, California); John Radcliffe Hospital (Oxford, United Kingdom), Guy's and St. Thomas' Hospital (London, United Kingdom), and The James Cook University Hospital (Middlesbrough, United Kingdom). Centers used a combination of preprocedural imaging and electroanatomical mapping the identify the optimal LVENDO site. A total of 26 patients across the 3 centers underwent a guided implant. Patients were predominantly male with a mean age of 68.8 ± 8.4 years, the mean LV ejection fraction was 34.2 ± 7.8%. The mean QRS duration was 163.8 ± 26.7 ms, and 30.8% of patients had an ischemic etiology. It proved technically feasible to selectively target and deploy the pacing electrode in a chosen endocardial segment in almost all cases, with a similar complication rate to that observed during indiscriminate BiVENDO. Ninety percent of patients met the definition of echocardiographic responder. Reverse remodeling was observed in 71%. Guided endocardial implants were associated with a higher degree of chronic LV remodeling compared with historical nonguided approaches.

Feasibility and safety of outpatient cardiac catheterization with intracoronary acetylcholine provocation test.

Intracoronary acetylcholine (ACh) provocation test is useful to diagnose vasospastic angina. Although outpatient coronary angiography has been widely performed in current clinical settings, the feasibility and safety of ACh provocation test in outpatient services are unclear. A total of 323 patients, who electively underwent ACh provocation test in hospitalization and outpatient services, were included. Coronary angiography was performed after insertion of a temporary pacing electrode in the right ventricle. The positive diagnosis of intracoronary ACh provocation test was defined as total or subtotal coronary artery narrowing accompanied by chest pain and/or ischemic electrocardiographic changes. Cardiac complications defined as composite of death, ventricular fibrillation or sustained ventricular tachycardia, myocardial infarction, cardiogenic shock, and cardiac tamponade, were evaluated. There were 201 patients (62%) in the hospitalization group and 122 patients (38%) in the outpatient group. The incidence of positive ACh provocation test was similar between the 2 groups (47 vs. 54%, p=0.21). Coronary angiography in the outpatient group was performed through the radial artery, mostly (98%) with a 4F sheath. Venous access site was not significantly different between the 2 groups, and the sheath size was 5F in all cases. There were 2 cases (1.0%) of cardiac complications in the hospitalization group, whereas 1 case (0.8%), which led to unexpected hospitalization, occurred in the outpatient group. In conclusion, intracoronary ACh provocation test for the diagnosis of vasospastic angina in outpatient services was feasible and safe in selected patients.

Could persistency of current of injury forecast successful active-fixation pacing lead implantation?

BackgroundPresence of adequate current of injury (COI) was recognized as a sign of favorable pacemaker lead outcome. Little is known regarding the value of its dynamic behavior. We sought to test whether persistency of COI could predict active-fixation pacing lead performance. MethodsCOI was monitored up to 10min after right ventricular (RV) pacing electrode fixation. COI persistency was defined as the percentage of COI magnitude relative to its initial measurement. An unacceptable pacing threshold (≥1.0V in acute evaluation or ≥2.0V over 2-year follow-up) with or without lead dislodgement was considered as lead failure. ResultsLead implantation was attempted for 217 times in 174 patients (age 66.3±7.8years, 78 female). Acute lead failures occurred 43 times. Independent predictors of acute lead failure were RV enlargement (odds ratio [OR] 1.23, 95% confidential interval [CI] 1.11–2.04, P=0.033), absence of COI (OR 3.13, 95%CI 2.08–9.09, P=0.027), and COI persistency at 5min (OR 0.32, 95%CI 0.20–0.69, P=0.001) and 10min (OR 0.41, 95%CI 0.13–0.77, P=0.001). The optimal cutoffs were COI5min persistency ≥50% (sensitivity 81.4%; specificity 81.9%) and COI10min persistency ≥20% (sensitivity 86%; specificity 88.6%). There were 12 lead failures during 24.0±6.4months of follow-up. Patients with COI5min persistency ≥50% had higher event-free survival compared to those with COI5min persistency <50% (hazard ratio 3.54, 95% CI 1.04–12.06, P=0.043). ConclusionsCOI persistency appears to be a valuable indicator for both acute and long-term outcome of active-fixation pacemaker leads. A precipitous decline in COI may require more attention to make sure of the lead performance.

Имплантация электрода для электрокардиостимуляции в вены сердца как альтернативный метод электрокардиостимуляции

В связи с различными заболеваниями проводящей системы сердца довольно часто возникает потребность в имплантации электрокардиостимулятора или имплантируемого кардиовертера-дефибриллятора. В настоящее время общепринятым методом стимуляции является имплантация электрода в верхушку правого желудочка или в межжелудочковую перегородку. Однако электрод, проходя через клапан, взаимодействует с его элементами и может вызывать нарушение функции клапана.

Canine Model of Pacing-Induced Heart Failure.

Tachypacing-induced heart failure is a well-established large animal model that recapitulates numerous pathophysiological, structural and molecular features of dilated cardiomyopathy and, more in general, of end-stage congestive heart failure. The left or the right ventricle is instrumented with pacing electrodes to impose supernormal heart rates, usually three times higher than baseline values, for a length of time that typically ranges between 3 and 5weeks. The animal of choice is the dog, although this protocol has been successfully implemented also in pigs, sheep, and rabbits. This chapter provides detailed methodology and description of the dog model utilized in our laboratory, which is one of the variants described in literature. Chronic instrumentation is completed by adding probes and catheters necessary to obtain measures of cardiac function and hemodynamics and to withdraw blood samples from various vascular districts. The progression from compensated to decompensated heart failure is highly reproducible, therefore, due also to the phylogenetic proximity of dogs to humans, tachypacing-induced heart failure is considered a highly clinically relevant model for testing the efficacy of novel pharmacological and nonpharmacological therapeutic agents. This model typically produces heart failure as defined by an LV dP/dt max <1500mmHg/s, end-diastolic pressure >25mmHg, mean arterial pressure <85mmHg, and an ejection fraction <35%. One can expect a mortality rate of 5-10% due to fatal arrhythmias.

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

It is now well recognized that heart failure (HF) patients with left bundle branch block (LBBB) derive substantial clinical benefits from cardiac resynchronization therapy (CRT), and LBBB has become one of the important predictors for CRT response. The conventional tachypacing-induced HF model has several major limitations, including absence of stable LBBB and rapid reversal of left ventricular (LV) dysfunction after cessation of pacing. Hence, it is essential to establish an optimal model of chronic HF with isolated LBBB for studying CRT benefits. In the present study, a canine model of asynchronous HF induced by left bundle branch (LBB) ablation and 4 weeks of rapid right ventricular (RV) pacing is established. The RV and right atrial (RA) pacing electrodes via the jugular vein approach, together with an epicardial LV pacing electrode, were implanted for CRT performance. Presented here are the detailed protocols of radiofrequency (RF) catheter ablation, pacing leads implantation, and rapid pacing strategy. Intracardiac and surface electrograms during operation were also provided for a better understanding of LBB ablation. Two-dimensional speckle tracking imaging and aortic velocity time integral (aVTI) were acquired to validate the chronic stable HF model with LV asynchrony and CRT benefits. By coordinating ventricular activation and contraction, CRT uniformed the LV mechanical work and restored LV pump function, which was followed by reversal of LV dilation. Moreover, the histopathological study revealed a significant restoration of cardiomyocyte diameter and collagen volume fraction (CVF) after CRT performance, indicating a histologic and cellular reverse remodeling elicited by CRT. In this report, we described a feasible and valid method to develop a chronic asynchronous HF model, which was suitable for studying structural and biologic reverse remodeling following CRT.

Completed FDA feasibility trial of surgically placed temporary diaphragm pacing electrodes: A promising option to prevent and treat respiratory failure

BackgroundEtiologies contributing to failure to wean from mechanical ventilation (MV) are multiple, resulting in morbid and costly outcomes. Diaphragm pacing (DP) is used in spinal cord injury to replace MV. Temporary DP could be utilized in acute respiratory failure to reduce MV. MethodsA prospective FDA feasibility trial evaluated temporary DP electrodes implanted in each hemi-diaphragm during a subject's primary procedure. Objectives included: ability to provide ventilation, stability analysis with diaphragm electromyography, and adverse event monitoring. ResultsTwelve patients underwent successful implantation via median sternotomy, laparoscopy or laparotomy. Electrode stimulation exceeded ideal tidal volumes by an average of 37% (0%–95%) confirming ability to prevent atrophy. Daily electromyography confirmed stability of placement and was useful in evaluating hypoventilation. There were no complications and all 48 study electrodes remained intact until complete removal. ConclusionThis trial demonstrates ease of placement, removal, functionality and safety of temporary DP electrodes which therapeutically decreases diaphragm atrophy.