Ventricular Sites Research Articles

Zero-fluoroscopy catheter ablation of premature ventricular contractions: comparative outcomes from the right ventricular outflow tract and other ventricular sites.

The three-dimensional electroanatomic mapping (EAM) system allows performing catheter ablation (CA) without fluoroscopy in patients with premature ventricular contractions (PVCs). The right ventricle outflow tract (RVOT) location is favorable for performing zero-fluoroscopy CA. Non-RVOT zero-fluoroscopy CA is a challenging procedure. The study aimed to evaluate the efficacy and safety of zero-fluoroscopy CA using the EAM in patients with PVCs from RVOT and non-RVOT. Completely zero-fluoroscopy CA of PVCs guided by EAM was performed in 107 patients with PVCs. 54 patients underwent zero-fluoroscopy RVOT CA. The remaining 53 patients underwent zero-fluoroscopy non-RVOT CA. Demographic and clinical baseline characteristics, procedure parameters, and follow-up were obtained from medical records. Primary outcomes were the acute and the permanent success rate (12-month follow-up), complications, and procedure time. There were no significant differences between groups regarding baseline characteristics. Acute procedural success was achieved in 52 patients (94,44%) in the RVOT zero-fluoroscopy CA group and in 45 patients (86,54%) in the non-RVOT zero-fluoroscopy CA group (ns). A long-term success rate was achieved in 50 patients (90,74%) in the RVOT zero-fluoroscopy CA group and in 44 patients (84,62%) in the non-RVOT zero-fluoroscopy CA group (ns). The median procedure time was 80.5 minutes in the RVOT group and 90 minutes in the non-RVOT group (ns). There were two complications in the non-RVOT group (ns). There were no differences in procedure time efficacy and safety zero-fluoroscopy ablation between RVOT and non-RVOT locations. Non-fluoroscopy CA of PVCs is a feasible, safe, and efficient procedure.

Distal Ventricular Pacing for Drug-Refractory Mid-Cavity Obstructive Hypertrophic Cardiomyopathy: A Randomized, Placebo-Controlled Trial of Personalized Pacing.

Patients with refractory, symptomatic left ventricular (LV) mid-cavity obstructive (LVMCO) hypertrophic cardiomyopathy have few therapeutic options. Right ventricular pacing is associated with modest hemodynamic and symptomatic improvement, and LV pacing pilot data suggest therapeutic potential. We hypothesized that site-specific pacing would reduce LVMCO gradients and improve symptoms. Patients with symptomatic-drug-refractory LVMCO were recruited for a randomized, blinded trial of personalized prescription of pacing (PPoP). Multiple LV and apical right ventricular pacing sites were assessed during an invasive hemodynamic study of multisite pacing. Patient-specific pacing-site and atrioventricular delays, defining PPoP, were selected on the basis of LVMCO gradient reduction and acceptable pacing parameters. Patients were randomized to 6 months of active PPoP or backup pacing in a crossover design. The primary outcome examined invasive gradient change with best-site pacing. Secondary outcomes assessed quality of life and exercise following randomization to PPoP. A total of 17 patients were recruited; 16 of whom met primary end points. Baseline New York Heart Association was 3±0.6, despite optimal medical therapy. Hemodynamic effects were assessed during pacing at the right ventricular apex and at a mean of 8 LV sites. The gradients in all 16 patients fell with pacing, with maximum gradient reduction achieved via LV pacing in 14 (88%) patients and right ventricular apex in 2. The mean baseline gradient of 80±29 mm Hg fell to 31±21 mm Hg with best-site pacing, a 60% reduction (P<0.0001). One cardiac vein perforation occurred in 1 case, and 15 subjects entered crossover; 2 withdrawals occurred during crossover. Of the 13 completing crossover, 9 (69%) chose active pacing in PPoP configuration as preferred setting. PPoP was associated with improved 6-minute walking test performance (328.5±99.9 versus 285.8±105.5 m; P=0.018); other outcome measures also indicated benefit with PPoP. In a randomized placebo-controlled trial, PPoP reduces obstruction and improves exercise performance in severely symptomatic patients with LVMCO. URL: https://clinicaltrials.gov/study; Unique Identifier: NCT03450252.

Intracranial Pressure Monitoring Location: A Pilot Study on the Validation of Subdural Site with the Intraventricular Site.

Introduction Knowledge of preoperative and intraoperative intracranial pressure (ICP) enables the neuroanesthesiologist to optimize cerebral perfusion pressure. However, ICP is rarely monitored during the intraoperative period. In this report, subdural site ICP measurement is validated with intraventricular ICP measurement, and the feasibility of subdural ICP monitoring during the intraoperative period is discussed. Materials and Methods In this prospective pilot study, ICP measurement at the subdural site was achieved with an intravenous cannula and the ventricular site with a ventricular cannula. Both were transduced using a fluid-filled pressure transducer and connected to the monitor for display of the number and the waveforms. Monitoring of intraoperative ICP using both the techniques was done in all patients recruited into the study. The correlation between the two modalities of measurement was studied by the Spearman correlation test and their limits of agreement were studied using the Bland-Altman plot. A case series describing the perioperative management based on the subdural ICP values are also described. Results Subdural ICP showed a strong correlation with intraventricular ICP ( r s = 0.93, p = 0.01). Agreement analysis using the Bland-Altman plot showed that the mean difference of ICP between the modalities was 1.44 mm Hg (95% confidence interval, -0.6 to 3.49, p = 0.122). Discussion This study validates the ICP values measured at the subdural site with the intraventricular site. Subdural site ICP monitoring can be achieved rapidly with readily available systems and helps in making intraoperative clinical decisions. Conclusion Cannula-based subdural ICP is a satisfactory alternative to intraventricular ICP monitoring in the intraoperative period.

Pacemaker-induced atrial fibrillation reconsidered-associations with different pacing sites and prevention approaches.

The incidence of atrial fibrillation (AF) is significantly higher in patients with pacemakers than in the general population, which could be due to patient characteristics and the diagnostic tool of the pacemaker in detecting atrial high-rate episodes and subclinical AF, but also to the pacemaker itself providing AF-promoting conditions. It is well known that high ventricular pacemaker burden increases the likelihood of AF occurrence. However, the sites of atrial and ventricular pacing may also influence the risk for AF. The conventional sites for atrial and ventricular pacing are in the right atrial appendage and in the right ventricular apex. However, growing evidence suggests that alternative pacing sites may be superior for the prevention of AF. Bachmann bundle pacing, for example, promotes interatrial excitation conduction, resulting in atrial synchronicity and a shorter total atrial activation time, which may be preventive for the occurrence of AF. Moreover, in recent years, new ventricular pacing sites have come into focus with His bundle and left bundle branch pacing. In addition to the hemodynamic and electrophysiological cardiac benefits, these new options may also offer benefits in the prevention of AF. This review provides an overview of pacing-induced AF mechanisms and the association with different pacing sites, as well as approaches for prevention of pacing-induced AF, highlighting different sites and modes of atrial pacing and the newer sites of ventricular pacing.

A porcine large animal model of radiofrequency ablation-induced left bundle branch block

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Medtronic Background and Objective ECG features of left bundle branch (LBB) block (LBBB) can be observed in up to 20–30 % of patients that suffer from heart failure with reduced ejection fraction. The resulting mechanical intraventricular asynchrony contributes to the worsening of left ventricular hemodynamics and has a relevant impact on the prognosis of the affected patients. The fact that we still cannot accurately predict which LBBB patients will benefit from cardiac resynchronization therapy (CRT) underscores that our understanding of the pathophysiology of LBBB remains incomplete. Here, a translational animal model of LBBB could be a major contributor to improving our knowledge of the molecular and translational pathomechanisms underlying LBBB. Methods A total of 15 male pigs underwent RF catheter ablation of the LBB, guided by fluoroscopy and intracardiac ECG signals. Before LBBB induction and after a follow-up period of one week or three weeks, a thorough clinical characterization was performed including 12-lead ECG, echocardiography, and electroanatomical mapping. To further test the feasibility of cardiac resynchronization in our model, 3 pigs were implanted with a CRT pacemaker on day seven after LBB ablation. Results Upon LBB ablation, 12-lead ECGs displayed typical characteristics of LBBB like a QRS broadening, a QRS slurring in left lateral leads, and a change of the QRS axis. The QRS width was prolonged from 64.2±4.2 ms to 93,4±7.4 ms and the R wave peak time in V6 was extended from 19.3±3.9 ms to 42.7±4.2 ms. Cardiac electromechanical asynchrony was further confirmed by echocardiography, where the appearance of a septal flash, the prolongation of the septal to posterior wall movement delay and extended left ventricular as well as interventricular electromechanical delays were documented. Electroanatomical mapping demonstrated a shift of the left ventricular breakthrough site. After LBBB-induction, left ventricular activation times, defined as the average of the maximum 10 % of activation times minus the average of the minimum 10 % of activation times were significantly prolonged from 36.3±7.1 ms to 60.8±10.2 ms while right ventricular activation times remained unchanged. Finally, RF-induced LBBB persisted over an observation period of three weeks. The pigs that underwent CRT showed a reduction in QRS duration from 99.1±8.2 ms on day seven after LBBB induction to 75.5±8.2 ms and echocardiography provided additional evidence of successful resynchronization. Conclusions In summary, our porcine large animal model accurately recapitulates the electrical and electromechanical phenotype, observed in LBBB patients. This closed-chest model of LBBB therefore provides an experimental platform to study both, molecular and translational characteristics of cardiac electromechanical asynchrony in a reproducible and clinically relevant setting.

Single-beat mapping during programmed ventricular stimulation identifies infarct-related ventricular tachycardia isthmus sites

Abstract Introduction Complete characterization of reentrant ventricular tachycardia (VT) circuits using classical electrophysiological criteria and high-density mapping during VT is complex. Often, VT episodes cannot be fully characterized because of hemodynamic instability during the mapping procedure. This common limitation has motivated the implementation of mapping strategies during sinus rhythm or ventricular pacing aiming to identify scar regions associated with VT isthmuses or potential arrhythmogenicity. However, these strategies still require time-consuming catheter-based mapping. Purpose We aimed to develop and validate a single-beat mapping strategy during programmed ventricular stimulation (PVS) to identify scar regions associated with VT isthmus sites. We hypothesize that protected VT isthmuses within scar regions are characterized by larger activation time dispersion than surrounding scar areas not related to critical isthmus sites. Methods Experimental study including 16 pigs with established myocardial infarction (MI) in the anterior wall. Ten-to-twelve weeks after MI, pigs underwent left ventricular characterization using 3D late-gadolinium enhancement cardiac magnetic resonance imaging, and further invasive electroanatomical mapping to obtain high-density sequential activation maps during ventricular pacing and VT. High-density maps were compared with single-beat maps using a 64-pole basket catheter positioned in the left ventricle. After VT induction, high-density activation maps in well-tolerated VT episodes were used to identify VT isthmus sites. Simultaneous activation data from the 64-pole basket catheter were also obtained during PVS and VT. Off-line analysis was performed to: (i) validate single-beat activation maps during the baseline drive pacing cycle length (S1), and (ii) identify basket-catheter electrodes with the larger local activation time-dispersion score (LAT-DS) during PVS including up to 4 coupled extrastimuli (S2, S3, S4, S5) (Figure 1). LAT-DS was defined as the normalized product of the LAT of each electrode and the activation dispersion among its neighboring electrodes. Results Basket-catheter based single-beat activation maps during S1 pacing showed high correlation values with high-density sequential activation maps (N=16. R²=0.91). In 7 pigs, the VT isthmus site was fully characterized using high-density activation maps. During any of the coupled extrastimuli of the PVS protocol, basket catheter electrodes colocalizing with documented VT isthmus sites on high-density maps showed higher LAT-DS values compared to surrounding electrodes located on scar or healthy regions. Conversely, LAT values alone could not differentiate scar regions relevant for VT maintenance during PVS protocol (Figure 2). Conclusions Sixty-four pole single-beat activation maps during PVS identify left ventricular scar areas with higher than surrounding LAT-DS values that are associated with VT isthmus sites.Figure 1.Experimental modelFigure 2.A-Example. B-C-Full results

Ablating Myocardium Using Nanosecond Pulsed Electric Fields: Preclinical Assessment of Feasibility, Safety, and Durability.

Unlike conventional microsecond pulsed electrical fields that primarily target the cell membranes, nanosecond pulses are thought to primarily electroporate intracellular organelles. We conducted a comprehensive preclinical assessment of catheter-based endocardial nanosecond pulsed field ablation in swine. A novel endocardial nanosecond pulsed field ablation system was evaluated in a total of 25 swine. Using either a low-dose (5-second duration) or high-dose (15-second duration) strategy, thoracic veins and discrete atrial and ventricular sites were ablated. Predetermined survival periods were <1 (n=1), ≈2 (n=7), ≈7 (n=6), 14 (n=2), or ≈28 (n=9) days, and venous isolation was assessed before euthanasia. Safety assessments included evaluation of esophageal effects, phrenic nerve function, and changes in venous caliber. All tissues were subject to careful gross pathological and histopathologic examination. All (100%) veins (13 low-dose, 34 high-dose) were acutely isolated, and all reassessed veins (6 low-dose, 15 high-dose) were durably isolated. All examined vein lesions (10 low-dose, 22 high-dose) were transmural. Vein diameters (n=15) were not significantly changed. Of the animals assessed for phrenic palsy (n=9), 3 (33%) demonstrated only transient palsy. There were no differences between dosing strategies. Thirteen mitral isthmus lesions were analyzed, and all 13 (100%) were transmural (depth, 6.4±0.4 mm). Ventricular lesions were 14.7±4.5 mm wide and 7.1±1.3 mm deep, with high-dose lesions deeper than low-dose (7.9±1.2 versus 6.2±0.8 mm; P=0.007). The esophagus revealed nontransmural adventitial surface lesions in 5 of 5 (100%) animals euthanized early (2 days) post-ablation. In the 10 animals euthanized later (14-28 days), all animals demonstrated significant esophageal healing-8 with complete resolution, and 2 with only trace fibrosis. A novel, endocardial nanosecond pulsed field ablation system provides acute and durable venous isolation and linear lesions. Transient phrenic injury and nontransmural esophageal lesions can occur with worst-case assessments suggesting limits to pulsed field ablation tissue selectivity and the need for dedicated assessments during clinical studies.

Ventricular insertion site ablation of a Mahaim atriofascicular fibre in Ebstein anomaly.

Ebstein anomaly is frequently associated with accessory pathways, including Mahaim atriofascicular fibres. We herein illustrate successful Mahaim fibre ablation in Ebstein anomaly by targeting the ventricular insertion site below the tricuspid ridge.

Characteristics of Right-Sided Accessory Pathways Associated With Right Cardiac Veins.

The anatomy of myocardial fibers around the right cardiac veins (RCVs) and their roles in accessory pathways (APs) are rarely reported. Six RCV-APs were identified from 566 patients with right-sided APs. Mapping of retrograde atrial activation was performed using CARTO 3 system under orthodromic tachycardia or right ventricular pacing. Venography of RCVs was acquired at the earliest retrograde atrial activation. Patients enrolled had a median age of 30 (11-51) years, 5 of them were male. Venography of RCVs could be classified into 3 distinct patterns based on the identified ventricular branches, right marginal vein only (type I; n=3), both right marginal vein and anterior cardiac veins (type II; n=2), and anterior cardiac vein only (type III; n=1). Patients with type I venography had rS QRS pattern in lead V1, negative delta wave in lead III and negative or isoelectric delta wave in lead aVF. However, patients with type II and III venography had QS QRS patterns in lead V1 and variable patterns of delta wave in inferior leads. Earliest retrograde atrial activation was found at a median of 16.75 (14.60-20.00) mm away from the tricuspid annulus, all with A larger than V. At the earliest retrograde atrial activation, far-field ventricular electrogram was found 30 ms later than QRS onset in 1 patient under sinus rhythm. AP conduction was eliminated by mechanical pressure in 2 and by radiofrequency ablation in 4 at the ostium of the veins colocalizing with the earliest retrograde activation of the right atrium. No recurrence was observed during 36 (10-60) months follow-up. The RCV-AP is a rare form of right-sided APs characterized by atrial insertions distant from the annulus. ECG-speculated ventricular insertion sites conformed to the location of identified RCVs.

Comparison between left bundle branch area pacing and right ventricular pacing: ventricular electromechanical synchrony and risk of atrial high-rate episodes.

The electromechanical dyssynchrony associated with right ventricular pacing (RVP) has been found to have adverse impact on clinical outcomes. Several studies have shown that left bundle branch area pacing (LBBAP) has superior pacing parameters compared with RVP. We aimed to assess the difference in ventricular electromechanical synchrony and investigate the risk of atrial high-rate episodes (AHREs) in patients with LBBAP and RVP. We consecutively identified 40 patients with atrioventricular block and no prior atrial fibrillation. They were divided according to the ventricular pacing sites: the LBBAP group and the RVP group (including the right ventricular apical pacing (RVA) group and the right side ventricular septal pacing (RVS) group). Evaluation of ventricular electromechanical synchrony was implemented using electrocardiogram and two-dimensional speckle tracking echocardiography (2D-STE). AHRE was defined as event with an atrial frequency of ≥176 bpm lasting for ≥6 min recorded by pacemakers during follow-up. The paced QRS duration of the LBBAP group was significantly shorter than that of the other two groups: LBBAP 113.56 ± 9.66 ms vs. RVA 164.73 ± 14.49 ms, p < 0.001; LBBAP 113.56 ± 9.66 ms vs. RVS 148.23 ± 17.3 ms, p < 0.001. The LBBAP group showed shorter maximum difference (TDmax), and standard deviation (SD) of the time to peak systolic strain among the 18 left ventricular segments, and time of septal-to-posterior wall motion delay (SPWMD) compared with the RVA group (TDmax, 87.56 ± 56.01 ms vs. 189.85 ± 91.88 ms, p = 0.001; SD, 25.40 ± 14.61 ms vs. 67.13 ± 27.40 ms, p < 0.001; SPWMD, 28.75 ± 21.89 ms vs. 99.09 ± 46.56 ms, p < 0.001) and the RVS group (TDmax, 87.56 ± 56.01 ms vs. 156.46 ± 55.54 ms, p = 0.003; SD, 25.40 ± 14.61 ms vs. 49.02 ± 17.85 ms, p = 0.001; SPWMD, 28.75 ± 21.89 ms vs. 91.54 ± 26.67 ms, p < 0.001). The interventricular mechanical delay (IVMD) was shorter in the LBBAP group compared with the RVA group (-5.38 ± 9.31 ms vs. 44.82 ± 16.42 ms, p < 0.001) and the RVS group (-5.38 ± 9.31 ms vs. 25.31 ± 21.36 ms, p < 0.001). Comparing the RVA group and the RVS group, the paced QRS duration and IVMD were significantly shorter in the RVS group (QRS duration, 164.73 ± 14.49 ms vs. 148.23 ± 17.3 ms, p = 0.02; IVMD, 44.82 ± 16.42 ms vs. 25.31 ± 21.36 ms, p = 0.022). During follow-up, 2/16 (12.5%) LBBAP patients, 4/11 (36.4%) RVA patients, and 8/13 (61.5%) RVS patients had recorded novel AHREs. LBBAP was proven to be independently associated with decreased risk of AHREs than RVP (log-rank p = 0.043). LBBAP generates narrower paced QRS and better intro-left ventricular and biventricular contraction synchronization compared with traditional RVP. LBBAP was associated with a decreased risk of AHREs compared with RVP.

A porcine large animal model of radiofrequency ablation-induced left bundle branch block.

Electrocardiographic (ECG) features of left bundle branch (LBB) block (LBBB) can be observed in up to 20%-30% of patients suffering from heart failure with reduced ejection fraction. However, predicting which LBBB patients will benefit from cardiac resynchronization therapy (CRT) or conduction system pacing remains challenging. This study aimed to establish a translational model of LBBB to enhance our understanding of its pathophysiology and improve therapeutic approaches. Fourteen male pigs underwent radiofrequency catheter ablation of the proximal LBB under fluoroscopy and ECG guidance. Comprehensive clinical assessments (12-lead ECG, bloodsampling, echocardiography, electroanatomical mapping) were conducted before LBBB induction, after 7, and 21days. Three pigs received CRT pacemakers 7days after LBB ablation to assess resynchronization feasibility. Following proximal LBB ablation, ECGs displayed characteristic LBBB features, including QRS widening, slurring in left lateral leads, and QRS axis changes. QRS duration increased from 64.2 ± 4.2ms to 86.6 ± 12.1ms, and R wave peak time in V6 extended from 21.3 ± 3.6ms to 45.7 ± 12.6ms. Echocardiography confirmed cardiac electromechanical dyssynchrony, with septal flash appearance, prolonged septal-to-posterior-wall motion delay, and extended ventricular electromechanical delays. Electroanatomical mapping revealed a left ventricular breakthrough site shift and significantly prolonged left ventricular activation times. RF-induced LBBB persisted for 3weeks. CRT reduced QRS duration to 75.9 ± 8.6ms, demonstrating successful resynchronization. This porcine model accurately replicates the electrical and electromechanical characteristics of LBBB observed in patients. It provides a practical, cost-effective, and reproducible platform to investigate molecular and translational aspects of cardiac electromechanical dyssynchrony in a controlled and clinically relevant setting.

Concept: Electrical Cardiac Stimulation is Detected by the Cardiac Autonomic Nervous System with Possible Effects on the Vasovagal Reflex

Abstract A novel concept is described concerning the possible effect of right ventricular pacing stimulation being detected by the cardiac autonomic nervous system and through its afferent neuronal connection to the central autonomic nervous system (spinal cord) causing reversal or attenuation of the vasovagal reflex. This could be a direct effect of electrical stimulation or may occur by the known adverse consequences on ventricular synchrony induced by stimulation which could be right ventricular site and timing in the evolution of the vasovagal reflex dependent.

Activation time at left ventricular pacing site (QLV) in relation to actual site of latest activation; effect on response to cardiac resynchronization therapy

Abstract Background Among techniques to improve CRT efficacy, longer QLV (activation time at the left ventricular (LV) pacing site (LVPS)) has been proposed to correlate to response to cardiac resynchronization therapy (CRT), supporting that pacing close to the latest LV electrically activated site (LEAS) improves CRT efficacy. A QLV cut-off of &amp;gt; 95 ms has been proposed, however, predictive value was modest. This may be because LEAS was not identified, and empirically delivered leads may have missed it (described by a longer interval QLEAS (activation time at LEAS) to QLV. Purpose We compared QLEAS to QLV, and assessed effect of the interval QLEAS-QLV, on response to CRT. Methods We studied patients who had received CRT for Class I or Class IIa indications, regardless of CRT response, at 5 European sites. LV lead placement, device programming and follow up (FU) followed physician preference and site protocol. All patients had clinical FU 6-12 months post-implant, including echocardiographic study. CRT non-response was defined as LV end-systolic volume (LVESV) reduction of &amp;lt;15%. Patients underwent noninvasive 3D electrical activation mapping and torso CT 6-24 months post-implant. QLV and QLEAS were assessed from the noninvasive activation map in a blinded core lab. Logistic regression modelling was conducted for QLV and the interval QLEAS-QLV against CRT response, and the optimal cut-off points were calculated. Results Of 111 patients (age 64±11 years (mean±SD), 74% male, 98% LBBB, QRS duration 172±21 ms, baseline LVEF 28±6%, LVESV 183±87 mL, implant duration 12±5 months, 31%/69% NYHA Class II/III, 38% ischemic heart disease), 67% responded at 10±3 months post-implant. QLV overall was 97±23 ms (range 42-148 ms), 103±21 ms for responders and 83±22 for non- responders (p&amp;lt;0.001), QLEAS was 109±19 ms (range 66-150 ms), 109±20 ms for responders and 110±19 ms for non- responders (p=0.74). QLEAS-QLV overall was 13±18 ms (range 0-120 ms), 6±10 ms for responders and 27±22 ms for non-responders (p&amp;lt;0.001) (Figure 1). Optimal cut-off point for QLV was 85 ms with sensitivity 0.89, specificity 0.57 and an AUC of 0.742 (95% CI: 0.637- 0.846). Optimal cut-off point for QLEAS-QLV was 6 ms (sensitivity 0.77, specificity 0.95, AUC 0.901 (95% CI: 0.844-0.957) (Figure 1). The AUC of QLV cut-off and QLEAS-QLV cut-off differed significantly (p&amp;lt;0.001). 18/111 patients (16%) were non-responders despite a QLV≥85 ms, whereas 2 patients (2%) were non-responders despite a QLEAS-QLV≤6 ms. Conclusion QLEAS has greater discriminatory power than a QLV cut-off of 85 ms to separate CRT responders from non-responders in patients with LBBB and long QRS duration. QLV guided LV lead placement without prior knowledge of the latest LV activation in individual patients will miss the ideal LV pacing site in 16% of cases. Using noninvasive 3D global mapping to identify LEAS pre-CRT implant and directing LV lead placement to within 6 ms of this may improve CRT efficacy.Figure 1

Left ventricular anterolateral site is the preferable left ventricular lead position for an upgrade to biventricular pacing

Abstract Background Cardiac resynchronization therapy (CRT) is a well-established treatment for symptomatic heart failure with electrical dyssynchrony. The LV lead position in patients with left bundle branch block is usually recommended at the LV posterolateral to the lateral site, which is the latest electrical activation site. In contrast, the preferable LV lead position in patients who plan to upgrade from conventional RV apical pacing to CRT remains unclear. Purpose This study aimed to identify the preferable LV lead position for upgrading to CRT from conventional RV apical pacing. Methods An electrophysiological study was performed on patients who underwent ablation for atrial fibrillation. The electrode catheters were positioned at the RV apex, LV anterolateral, and LV posterolateral sites via the coronary sinus branches. During RV apical pacing, the activation time from the RV apex to the LV anterolateral and posterolateral sites was measured, and the activation time ratio to QRS duration was calculated. Biventricular pacing from both the RV apex and LV anterolateral or LV posterolateral sites was performed, and the difference in QRS duration and LV dP/dt compared to only the RV apical pacing state was measured. Results We enrolled 37 patients who exhibited anterolateral and posterolateral LV coronary sinus branches. During RV apical pacing, the average activation time ratio to QRS duration was higher at the LV anterolateral site than at the LV posterolateral site (0.89±0.07 vs. 0.71±0.11, P &amp;lt;0.001). The shortening ratio of QRS duration during biventricular pacing compared to baseline RV apical pacing was greater at LV anterolateral site than at the LV posterolateral site (45.7±18.0% vs. 32.0±17.6%, P &amp;lt;0.001). The improvement ratio of LV dP/dt during biventricular pacing was also better from the LV anterolateral site than from the LV posterolateral site (12.7±8.9% vs. 3.7±8.2%, P &amp;lt;0.001). Conclusion LV lead position in patients who plan to upgrade to CRT from conventional RV apical pacing is preferably at the LV anterolateral site.

Pulsed field ablation and ventricular capture: assessing the need for R-wave gated therapy

Abstract Background Pulsed field ablation (PFA) is a therapy that disrupts cellular homeostasis by applying high intensity and short duration electrical pulses to cardiac tissue, ultimately resulting in cell death. Such stimuli have the potential to initiate ventricular arrhythmias if the therapy is not synchronized with the beginning of ventricular systole (R-wave gating). For the treatment of cardiac arrhythmias, it is important that the candidate therapy locations in the left atrium (e.g., pulmonary veins) are a sufficient distance away from ventricular tissue to avoid ventricular capture. Objective data exploring the need for R wave gating in the context of PFA therapy for pulmonary vein isolation is currently lacking. Purpose To study the effect of electrode distance of the 12-electrode loop catheter from the epicardium on likelihood of ventricular capture. Methods A sternotomy was performed on swine to expose the heart. An incision was then made in the pericardial sac and the edges were lifted and sutured to the surrounding chest cavity to create a cradle. The function of the cradle was to hold a ∼37C saline solution (tuned to match the electrical conductivity of blood) while PFA treatments were performed. Two left ventricular sites (apex and lateral aspect) were selected for treatment, taking care to avoid proximity to the coronary artery. For each PFA therapy trial, the catheter loop was positioned 10mm above the surface of the epicardium and then advanced in 1mm increments until capture was achieved; spacers were used to assure fixed spacing during cardiac activity. For each trial, the maximum distance between the catheter and the epicardium at which the IRE therapy captured the ventricle was recorded. Additionally, CT scans (N=20 human patients) were analyzed to understand distances of interest to ventricular tissue. Results N=12 trials were conducted at each target in each animal (N=48 total ablations). For all trials, the minimum capture distance was found to be 6-8mm (4/48 at 6mm, 28/48 at 7mm and 16/48 at 8mm), with a mean capture distance of 7.25±0.60mm. The mean capture distances for the left ventricular apex and lateral aspect were 7.29±0.55mm and 7.21±0.66mm, respectively (p=0.636). For the CT scan analysis, the minimum distance from pulmonary vein ostia to left ventricular tissue ("nominal case") were 10.6mm and 12.8mm for the left superior and inferior veins, respectively. Considering the use ("worst case") where the catheter is placed just distal to the ostia, the distances to ventricular tissue were 1.6mm and 5.8mm, respectively; 4/20 patients had a vein less than 10mm from ventricular myocardium. Conclusions This study was successful in establishing the distance of ventricular capture via PFA therapy (6-8mm for the considered therapy). Given the described use and CT analysis, there is potential risk in triggering ventricular arrhythmia via PFA therapy unless R-wave triggering is implemented.

Acute Hemodynamic Effect of a NovelDual-Vein, Multisite Biventricular Pacing Configuration.

Biventricular pacing (BVP) from multiple left ventricular (LV) sites could enhance the efficacy of cardiac resynchronization therapy (CRT) by engaging a greater myocardial mass. The goal of this study was to evaluate the acute hemodynamic effect of various multisite pacing (MSP) configurations against conventional BVP. Twenty patients with nonischemic dilated cardiomyopathy and left bundle branch block (mean age: 59 ± 14 years; LV ejection fraction: 27% ± 6%; native QRS: 171 ± 16 milliseconds) were investigated during a routine CRT implant procedure. In addition to conventional right atrial and right ventricular leads, 2 quadripolar leads were placed in the distant coronary venous branches. LV hemodynamics was evaluated by using a micromanometer-tipped catheter during atrioventricular BVP with 4 LV lead configurations: single-lead conventional BVP; single-lead multipoint pacing; triventricular pacing from distal dipoles of 2 LV leads; and maximum MSP (MSP-Max) from 4 dipoles of 2 LV leads. Compared with right atrial pacing, any BVP configuration produced a significant increase in the maximal LV diastolic pressure rise (LVdP/dTMax) (amedian relative increase of 28% [IQR: 8%-45%], 25% [IQR: 18%-46%], 36% [IQR: 18%-54%], and 38% [IQR: 28%-58%], respectively; all, P< 0.001). MSP-Max but no other multisite BVP generated a significant increase of the maximal LVdP/dTMax than conventional BVP (P=0.041). Increased LVdP/dTMax during MSP-Max was associated with greater LV diameter and lower LV ejection fraction, independently of the QRS width. The study shows the hemodynamic advantage of a novel dual-vein MSP-Max configuration that could be useful for CRT in patients with advanced LV remodeling.

A novel automated peak frequency annotation algorithm for identifying deceleration zones and ventricular tachycardia ablation sites

BackgroundCurrent annotation of local fractionated signals during ventricular electroanatomic mapping (EAM) requires manual input subject to variability and error. ObjectivesThe purpose of this study was to evaluate a novel peak frequency (PF) annotation software for its ability to automatically detect late potentials (LPs) and local abnormal ventricular activity (LAVA), determine an optimal range for display, and assess its impact on isochronal late activation mapping (ILAM). MethodsEAM data from 25 patients who underwent ventricular tachycardia (VT) ablation were retrospectively analyzed. Samplings of electrogram PFs from areas of normal bipolar voltage, areas of low voltage, and areas of low voltage with fractioned signals were performed. An optimal range of frequency display was identified from these patients and applied to a validation cohort of 10 prospective patients to assess high PF within scar as a predictor of VT ablation target sites, in particular deceleration zones (DZs) identified by ILAM, LP, and LAVA. ResultsVoltage and PF ranges of normal endocardial tissue varied widely. Using 220 Hz as a frequency cutoff value in areas of low bipolar voltage, areas of high fractionation were identified with sensitivity of 91% and specificity of 85% There was no significant reduction in targeted DZ surface areas, and colocalization with DZs was observed in all cases. Applied to the prospective cohort, PF predicted fractionated areas and DZ in 9 of 10 patients. ConclusionA PF annotation algorithm with a cutoff of 220 Hz accurately identifies areas of fractioned signals and accurately predicts DZs during ILAM.

CRT non-responder to responder conversion rate in the MORE-CRT MPP Trial.

To assess the impact of MultiPoint™ Pacing (MPP) in cardiac resynchronization therapy (CRT) non-responders after six months of standard biventricular pacing (BiVP). The trial enrolled 5,850 patients who planned to receive a CRT device. The echocardiography core laboratory assessed CRT response before implant and after six months of BiVP; non-response to BiVP was defined as < 15% relative reduction in left ventricular end-systolic volume (LVESV). Echocardiographic non-responders were randomized in a 1:1 ratio to receive MPP (541 patients) or continued BiVP (570 patients) for an additional six months and evaluated the conversion rate to the echocardiographic response. The characteristics of both groups at randomization were comparable. The percentage of non-responder patients who became responders to CRT therapy was 29.4% in the MPP arm and 30.4% in the BIVP arm (p=0.743). In patients with > 30 mm spacing between the two left ventricular pacing sites (MPP-AS), identified during the first phase as a potential beneficial subgroup, no significant difference in the conversion rate was observed. Our trial shows that approximately 30% of patients, who do not respond to CRT in the first six months, experience significant reverse remodeling in the following six months. This finding suggests that CRT benefit may be delayed or slowly incremental in a relevant proportion of patients and that the percentage of CRT responders may be higher than what has been described in short/middle-term studies. MPP does not improve CRT response in non-responders to BiVP, even with MPP-AS.

Left ventricular endocardial activation maps during right ventricular pacing in pediatric patients.

Cardiac pacing from right ventricular (RV) sites may cause electromechanical ventricular dyssynchrony. Invasive and noninvasive mapping studies showed left ventricular (LV) activation sequence in adults. Aim of this study was to seek out the LV endocardial activation (LVEA) in pediatric patients who underwent RV pacing. Single-center, prospective study conducted on pediatric patients who underwent left sided catheter ablation of accessory pathways with the Carto Univu mapping system. After successful ablation procedures, LVEA was recorded by the ablation catheter during sinus rhythm (SR) and during para-hisian (PHP), midseptum (MSP), and apical (RVAP) pacing. Seventeen patients, 13 males, aged 12 (10-15) years, registered LV activation maps and times (LVAT). SR showed significantly shorter LVAT than during pacing. LVAT of PHP was shorter than MSP, while there were not significant differences among PHP and MSP versus RVAP. In SR initial LV endocardial activation occurred in two midseptum sites, inferior-posterior and superior-anterior. During PHP, initial activation occurred at parahisian basal septum, rapidly followed by midseptum as in SR. During MSP and RVAP initial activation occurred at midseptum and apex, respectively. From all initial sites, the excitation spreads toward the base of the lateral LV free wall. A mild linear correlation was found between QRS duration and LVAT for MSP and for PHP. In pediatric patients LVEA maps during RV pacing showed that the shortest LVAT was obtained with PHP. The LV activation pattern seemed similar in sinus rhythm, PHP and MSP, from midseptum to LV lateral base.

Clinical outcomes of transcatheter mitral valve replacement: two-year results of the CHOICE-MI Registry.

Transcatheter mitral valve replacement (TMVR) using dedicated devices is an alternative therapy for high-risk patients with symptomatic mitral regurgitation (MR). This study aimed to assess the 2-year outcomes and predictors of mortality in patients undergoing TMVR from the multicentre CHOICE-MI Registry. The CHOICE-MI Registry included consecutive patients with symptomatic MR treated with 11different dedicated TMVR devices at 31 international centres. The investigated endpoints included mortality and heart failure hospitalisation rates, procedural complications, residual MR, and functional status. Multivariable Cox regression analysis was applied to identify independent predictors of 2-year mortality. Atotal of 400patients, median age 76 years (interquartile range [IQR] 71, 81), 59.5% male, EuroSCORE II 6.2% (IQR 3.8, 12.0), underwent TMVR. Technical success was achieved in 95.2% of patients. MR reduction to ≤1+ was observed in 95.2% at discharge with durable results at 1 and 2years. New York Heart Association Functional Class had improved significantly at 1 and 2years. All-cause mortality was 9.2% at 30days, 27.9% at 1year and 38.1% at 2years after TMVR. Chronic obstructive pulmonary disease, reduced glomerular filtration rate, and low serum albumin were independent predictors of 2-year mortality. Among the 30-day complications, left ventricular outflow tract obstruction, access site and bleeding complications showed the strongest impact on 2-year mortality. In this real-world registry of patients with symptomatic MR undergoing TMVR, treatment with TMVR was associated with adurable resolution of MR and significant functional improvement at 2years. Two-year mortality was 38.1%. Optimised patient selection and improved access site management are mandatory to improve outcomes.