Ventricular Sites Research Articles

Risk of pacing-induced cardiomyopathy in patients with high-degree atrioventricular block – comparison between right ventricular pacing sites using computed tomography

Abstract Background Right ventricular (RV) pacing may induce significant left ventricular (LV) dyssynchrony resulting in pacing-induced cardiomyopathy (PICM). LV activation sequence is affected by RV pacing site and previous studies suggest that RV septal pacing may be superior compared to traditional RV apical pacing. However, results are conflicting and randomized controlled trials have failed to show clear benefits from RV septal pacing. Traditionally, studies have applied fluoroscopy to determine RV lead implantation site. However, locating pacing site using this method is known to be inaccurate and poorly reproducible compared with cardiac computed tomography (CT). The purpose of our study was to evaluate the association between RV pacing site determined by cardiac CT and risk of PICM. Methods We retrospectively included 153 patients with pre-implant LV ejection fraction (LVEF) ≥50% who underwent fluoroscopy-guided dual chamber pacemaker implantation due to high-degree atrioventricular block between March 2012 and May 2020. All patients attended a follow-up visit including cardiac CT and transthoracic echocardiography. RV lead position was evaluated from CT dividing the RV into three segments: apical, septum or free wall (Figure 1). Furthermore, RV lead position estimated by the implanting physician, using fluoroscopy during pacemaker implantation, was retrieved from medical records. The primary endpoint was PICM defined as ≥10% decrease in LVEF from time of pacemaker implantation to follow-up, resulting in LVEF <50%. Results Mean duration of follow-up was 3.7 years (range 2.1–8.7). The implanting physician estimated 131 (85.6%) leads to be located septal, 5 (3.3%) located non-septal and 17 (11.1%) were unknown. Based on CT, 48 (31.4%) leads were located septal and 105 (68.6%) were located non-septal of which 31 were located on the free wall (20.4%). With CT as the golden standard, 47 (35%) leads were estimated correctly during fluoroscopy-guided implantation. No significant differences between patient characteristics in the CT-estimated septal and non-septal groups were observed except for ischemic heart disease (P=0.05) (Table 1). There were 16 (33.3%) patients in the septal group who developed PICM compared to 31 (29.5%) in the non-septal group (P=0.6). Adjusting for ischemic heart disease did not change this result. In the septal group, the change in LVEF from baseline to follow-up was −9.0±10.4% compared to −7.5±9.1% in the non-septal group (P=0.4). Conclusion In total 31% developed PICM despite having a normal pre-implant LVEF with no observed difference between RV septal and non-septal pacing. With CT as the golden standard, RV leads were inaccurately located during fluoroscopy-guided pacemaker implantation with only 35% being located correctly. Misclassification of pacing sites in previous studies may have contributed to the inconsistent results. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Svend Andersens FondKarl G Andersens Fond

Predictors of right ventricular pacing-induced left ventricular dysfunction in pacemaker recipients with preserved ejection fraction

Pacing is an effective treatment in the management of patients with bradyarrhythmias. Chronic right ventricular pacing may cause electrical and mechanical dyssynchrony leading to adeterioration of left ventricular ejection fraction (LVEF). This deterioration of LVEF has been described as pacing-induced cardiomyopathy (PICM). The incidence of PICM has been described by many studies, ranging between 10% and 26%. Predictors for PICM are not yet established-studies were limited by variations in the definition of PICM and the follow-up period. The authors studied the incidence and predictors of PICM in patients with preserved LVEF who underwent pacemaker implantation. This retrospective study included 320patients that underwent single- or dual-chamber pacemaker implantation, with amean follow up period of 4.7 ± 2.0years. Implantable cardioverter defibrillator and cardiac resynchronization therapy patients were excluded from this study. Individuals that had abaseline LVEF ≥ 50% before implantation in transthoracic echocardiography were included in the study. Of the 320patients included in the study, 45% were male, with amean age 55.5years. The incidence of PICM was 7.5%. Wider native QRS duration, particularly > 140 ms (P < 0.001), wider paced QRS (pQRS) duration > 150 ms (P < 0.001), low normal ejection fraction < 56% pre-implantation (P = 0.023) and increased LV end diastolic diameter (LVEDD) > 53 mm and LV end systolic diameter (LVESD) > 38 mm (P < 0.001) predicted the development of PICM. There was no association between burden of right ventricular pacing (P = 0.782) or pacing site (P = 0.876) and the development of pacemaker-induced cardiomyopathy. Right ventricular pacing-induced left ventricular dysfunction is not uncommon, with an incidence of 7.5%. Wider native and paced QRS durations, low normal ejection fraction (< 56%) pre-implantation and increased LVEDD and LVESD post implantation are the most important predictors for the development of PICM.

To go left or right? Driving towards the best direction in paediatric pacing.

Permanent pacing in children with isolated congenital complete atrioventricular block may cause left ventricular dysfunction. To prevent it, alternative pacing sites have been proposed: left ventricular epicardial or selective right ventricular endocardial pacing. To compare the functional outcome (left ventricular systolic function and synchrony) in paediatric patients with congenital complete atrioventricular block and left ventricular apical epicardial or right ventricular transvenous mid-septal pacing. Retrospective study. Epicardial leads were implanted by standard surgical technique, transvenous leads by 3D electroanatomic mapping systems. 3D mapping acquired 3D right ventricular local pacing map and defined the narrowest paced QRS site. 3D mapping guided screw-in bipolar leads on that ventricular site. Electrocardiogram (ECG) (QRS duration) and echocardiographic data (synchrony: interventricular mechanical delay, septal to posterior wall motion delay, systolic dyssynchrony index; contractility: global longitudinal strain, ejection fraction) were recorded. Data are reported as median [interquartile ranges]. p < 0.05 was significant. There were 19 transvenous systems (age 8.8 [6-14] years; right ventricular mid-septum) and 17 epicardial systems (0.04 [0.001-0.6] years; left ventricular apex). Post-implantation QRS significantly widened either in endocardial or in epicardial patients. Most patients reached 4-year follow-up. One-year and 4-year ejection fraction and global longitudinal strain were mostly within normal limits and did not show significant differences between the two groups and between the same endocardial/epicardial group. Synchrony parameters were within normal limits in the two groups. Left ventricular apical epicardial pacing and 3D mapping-guided right ventricular mid-septal pacing preserved left ventricular contractility and synchrony in children and adolescents with congenital complete atrioventricular block at short-/mid-term follow-up, without relevant significant differences between the two groups.

Status and Update on Cardiac Resynchronization Therapy Trials.

After decades of clinical use, cardiac resynchronization therapy (CRT) can be considered an established therapy. However, there are multiple open questions to be addressed that shall further improve the proportion of patients responding to CRT. Progress in better understanding the relationship between electrical and mechanical disorder in patients with heart failure with ventricular conduction abnormalities is important. This article presents and discusses ongoing studies in different areas of CRT research, including patient selection by novel diagnostic tools, extension of clinical criteria, left ventricular lead positioning and pacing site selection, optimization of CRT delivery and programming, and selection of device type.

Influence of the right ventricular septum/free-wall boundary (hinge) on differentiation of the ventricular lead implantation site

BackgroundThe prognosis associated with right ventricular (RV) free-wall pacing is worse than that of septal pacing. Identification of the pacing site using a 12‑lead electrocardiogram (ECG) is controversial and may be influenced by ECG changes within the same septal or free-wall area. The relationship between the diagnostic capabilities of ECG and pacing sites has previously been qualitatively evaluated. However, in this study, this relationship was analyzed quantitatively, and accurate evaluation of the pacing site was determined using computed tomography (CT). MethodsOf 779 consecutive outpatients, 65 who underwent pacemaker implantation and thoracic CT were prospectively included and classified into the following groups according to the lead tip position: free-wall, septal, or septum/free-wall boundary (hinge) group. The hinge was used as an anatomical marker, and the distance from the hinge to the lead tip was measured. Under RV pacing, a 12‑lead ECG was obtained. ECG findings were evaluated using three criteria (including lead I, II, and aVL and precordial leads V5 and V6) previously reported to be useful in differentiating pacing sites. ResultsThe lead tips were anchored at the free-wall in 10 patients, the septal wall in 19 patients, and the hinge in 32 patients. Paced QRS duration correlated with the distance from the hinge to the lead tip for the free-wall and septum (r = 0.47 and − 0.68, respectively). Estimation of the lead tip implantation site using the ECG algorithm was useful; however, the algorithm's accuracy decreased around the hinge. ConclusionsECG is useful in differentiating pacing sites but is less accurate around the hinge, which may be the reason that the identification of the RV pacing site using ECG remains controversial.

Transvenous lead advancement in paediatric pacing to overcome growth stretching

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction One of the main complications of transvenous leads implanted in paediatric patients is the stretching of the lead caused by the somatic growth. It may cause pacing and sensing defects and lead dislodgement or even fracture. Absorbable lead ligature and atrial loop may reduce this risk. However, the loop may induce traction or may unroll too early and therefore impair lead function. Lead extraction and replacement is another solution, although it has some procedural risks in young patients. Lead advancement through pushing it from the pocket may solve growth-induced traction and spare the electrode throughout childhood until post-puberty. Purpose of the study is the retrospective analysis of the outcome of the transvenous lead advancement in children with a pacemaker (PM) in a single tertiary paediatric center. Methods Consecutive patients with a VVIR PM implanted for isolated congenital complete atrioventricular block (no structural heart disease) in alternative right ventricular (RV) pacing sites, with lead stretching underwent a trial of lead advancement during general anaesthesia, cefuroxime antibiotic profilaxis, from 2014 to 2021. After venous angiography showed venous patency, the PM pocket was opened, the lead was released from subcutaneous adherences and with a stylet was gently advanced to create a semi-loop in the atrium without dislodging the tip. Lead data (threshold, sensing, impedance) were compared before and after the procedure. Data are expressed as median (25th-75th centiles) Results: 7 patients underwent PM implantation at 6.9 (5.5-8.0) years of age, 20 (18-21) kg, 116 (106-120) cm, with the lead positioned at parahisian(3)/mid-septum (4 pts) sites. During a follow-up of 3 (1-5) years, advancement procedures were 2 (1-4) per patient. Between procedures, delta age was 15 (12-19) months, height 7 (6-11) cm and weight 4 (2-6) kg. All leads were successfully advanced without any procedural complications. Procedure time (skin to skin) was 91 (69-105) minutes, fluoroscopy was 0.4 (0.2-1.2) mGy, 13 (9-35) microGy/m2. Electrical lead parameters did not showed significant differences between consecutive control times. In one parahisian pacing, chronic threshold increased after 3 years (2 advancement procedures) from 0.7V to 2.6 V/0.4 ms. Conclusion the advancement of transvenous leads in children is a safe and effective procedure, without significant procedural complications and during follow-up, and with low fluoroscopy exposure. This procedure may maintain a good function of transvenous leads until growth has completed.

Novel multi-site, multi-point biventricular pacing configuration: acute haemodynamic benefit

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by the research grant of the AZV (Ministry of Health of the Czech Republic) Background Biventricular pacing (BVP) using multiple left ventricular (LV) sites may augment the hemodynamic effect of cardiac resynchronisation therapy (CRT) by engaging a greater mass of the myocardium. Purpose To evaluate the acute hemodynamic effect of a novel multi-site, multi-point BVP configuration. Methods The study investigated 18 patients with idiopathic dilated cardiomyopathy and left bundle-branch block during implantation of a BVP device (age: 59 ± 14 years, female gender: 7 [39%], LVEF: 27 ± 6%, native QRS: 171 ± 16 ms). Conventional leads were placed in the right atrium (RA) and ventricle (RV), one quadripolar LV lead (Quartet, Abbott, Abbott Park, IL, USA) was positioned in the posterolateral and another one in lateral or anterolateral coronary vein. Individual bipoles of all leads were connected through a splitter to separate external cardiac stimulators. Hemodynamics was evaluated using a micromanometer-tipped catheter (Micro-Cath, Millar, Tx, USA) located in the LV during RA pacing above sinus rate and five atrio-ventricular sequential pacing configurations at the same rate: 1.) RA+RV, 2.) RA + RV + distal bipole of the LV lead with greater dP/dT („conventional BVP"), 3.) RA + RV + distal and proximal bipoles of the LV lead with greater dP/dT („single-lead multi-point BVP"), 4.) RA + RV + distal bipoles of both LV leads („two-lead multi-site BVP"), and 5.) sequentional pacing RA + RV + all bipoles of both LV leads interconnected to a mesh („maximum BVP"). Results Compared to RA pacing, LV dP/dT was significantly greater during all BVP pacing configurations (RA pacing: 1940 ± 507 mmHg/s vs. conventional BVP: 2431 ± 855 mmHg/s, single-lead multi-point BVP: 2539 ± 740 mmHg/s, two-lead multisite BVP: 2517 ± 836 mmHg/s, and "maximum BVP": 2685 ± 893 mmHg/s, all p&amp;lt;0.001, Figure 1), but not during RA-RV pacing (2014 ± 721 mmHg/s, p=0.12). In addition, dP/dT was significantly greater during "maximum BVP" compared to conventional BVP (p=0.05). Conclusion Compared to RA pacing and conventional BVP, the greatest increase in LV contractility was achieved with a novel multi-site, multi-point "maximum BVP" configuration. These preliminary findings provide a rationale for designing new approaches to CRT.

Periaortic scar-related ventricular tachycardia in patients with aortic valve replacement: transcatheter ablation is feasible and decisive

Abstract Funding Acknowledgements Type of funding sources: None. Background Aortic valve replacement (AVR) is a common procedure. While conduction disturbances are well-recognized complications, ventricular tachycardias (VTs) have not been widely reported neither described mainly because prosthetic valves represent a potential practical problem in the access to the ventricles, and this may limit the use of radiofrequency ablation (RF). Purpose and Methods We report three cases of periaortic scar-related VT in patients with AVR. Results The first case was a 85 years old (yo) man, with both aortic and mitral biological valve replacement. The left ventricular ejection fraction (LVEF) was normal and the clinical VT (left bundle branch block (BBB) and inferior axis, cycle length (CL) = 305 ms) was induced. Left ventricle (LV) was mapped with a retrograde transaortic approach: to cross safely the prosthesis, a 6-French (F) pigtail catheter was first placed in the ventricle; a 8.5-F Braided Guiding Introducer (SL1) was placed across the valve over a guidewire. The 8.5-F ablation catheter allowed to locate the VT origin underneath the septal portion of prosthetic aortic valve (PAV). The second case was a 85 yo man, with bioprosthetic AVR and replacement of the ascending aorta. LVEF was 40% with mild PAV degeneration. The clinical VT had left BBB morphology and inferior axis (CL = 352 ms). Transaortic approach was hampered by an unfavorable entry angle and by valve degeneration. Then we opted for the technique commonly used during transcatheter AVR: the access to the LV was obtained using a 6-F coronary catheter (AL1) and a stright tip 0.034" angiographic guidewire; subsequently a 8.5-F, 81 cm long, introducer sheath (SL0) was positioned across the PAV. The reentry circuit was mapped in the high anterior region, just below the PAV insertion. The third case was a 65 yo man, with mechanical PAV. LVEF was normal and the clinical VT had right BBB and left inferior axis (CL = 290 ms). After transseptal puncture, a steerable introducer was placed in left atrium. The mapping catheter allowed to identify early and fractional potentials in the anterior portion of PAV. In all cases, RF applications was delivered at the earliest ventricular activation site with termination of the VTs. Thereafter, no VTs could be induced. At 12 months follow-up, the patients are free of any VT relapses. Conclusions The most common origin of sustained monomorphic VT occurring after PAV is the surgical scar and catheter ablation is a feasible option. In case of mechanical PAV, the only practicable access is the transeptal one; on the contrary, with biological PAV the transaortic approach can also be used. In difficult cases, the access to the LV can be obtained with the technique routinely performed during transcatheter AVR.

Accuracy of non-invasive anatomical lead localization in CRT patients: BSPM vs 12-lead ECG

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant agency AZV, Ministry of Health of the Czech Republic Background Non-invasive, inverse ECG (iECG), estimating the cardiac activation from ECG signals, may be useful both to support CRT implant and optimization. However, most iECG strategies require a 32-250 electrode body surface potential mapping (BSPM), limiting their clinical utility. Objective This proof of concept study evaluates the accuracy of our novel PaceView iECG method to localize the LV/RV pacemaker lead to the cardiac anatomy using either a 96-electrode BSPM or the 12-lead ECG. Methods PaceView generates activation sequences in combination with the equivalent double layer source model to simulate the corresponding ECG signals. An initial activation sequence is iteratively optimized to match simulated and measured ECG signals. A BSPM with 96 electrodes and CT were recorded for every patient with implanted CRT. The CT was used to create patient-specific heart/torso model and to localize the ECG electrodes and CRT leads. From a BSPM, 9 signals were selected to obtain the 12-lead ECG. Both BSPM and 12-lead ECG were used to localize the RV/LV lead as the earliest ventricular activation site. Results In this study 14 consecutive patients with dilated cardiomyopathy were enrolled: mean age 58±9 years, 7 females. The localization error for the RV/LV lead was 10.4±5.4 (max 22) / 11.3±5.5 (max 20.4) mm using the 12 lead ECG and 11.7±6.1 (max 26.2) / 13.5±5.8 (max 24.5) mm for the BSPM. The time used for a 3D activation map computation was 0.9-1.8 s. Conclusion Our preliminary results show that the non-invasive lead localization error, using the 12-lead ECG, is small and comparable with a 96-lead BSPM. Therefore PaceView might be clinically beneficial, by actively localizing the LV/RV pacing sites during CRT implant, and optimize AV or VV delays at CRT follow-ups.

CMR findings after COVID-19 and after COVID-19-vaccination—same but different?

Cardiac involvement has been described in varying proportions of patients recovered from COVID-19 and proposed as a potential cause of prolonged symptoms, often described as post-COVID or long COVID syndrome. Recently, cardiac complications have been reported from COVID-19 vaccines as well. We aimed to compare CMR-findings in patients with clinical cardiac symptoms after COVID-19 and after vaccination. From May 2020 to May 2021, we included 104 patients with suspected cardiac involvement after COVID-19 who received a clinically indicated cardiac magnetic resonance (CMR) examination at a high-volume center. The mean time from first positive PCR to CMR was 112 ± 76 days. During their COVID-19 disease, 21% of patients required hospitalization, 17% supplemental oxygen and 7% mechanical ventilation. In 34 (32.7%) of patients, CMR provided a clinically relevant diagnosis: Isolated pericarditis in 10 (9.6%), %), acute myocarditis (both LLC) in 7 (6.7%), possible myocarditis (one LLC) in 5 (4.8%), ischemia in 4 (3.8%), recent infarction in 2 (1.9%), old infarction in 4 (3.8%), dilated cardiomyopathy in 3 (2.9%), hypertrophic cardiomyopathy in 2 (1.9%), aortic stenosis, pleural tumor and mitral valve prolapse each in 1 (1.0%). Between May 2021 and August 2021, we examined an additional 27 patients with suspected cardiac disease after COVID-19 vaccination. Of these, CMR provided at least one diagnosis in 22 (81.5%): Isolated pericarditis in 4 (14.8%), acute myocarditis in 9 (33.3%), possible myocarditis (acute or subsided) in 6 (22.2%), ischemia in 3 (37.5% out of 8 patients with stress test), isolated pericardial effusion (> 10 mm) and non-compaction-cardiomyopathy each in 1 (3.7%). The number of myocarditis diagnoses after COVID-19 was highly dependent on the stringency of the myocarditis criteria applied. When including only cases of matching edema and LGE and excluding findings in the right ventricular insertion site, the number of cases dropped from 7 to 2 while the number of cases after COVID-19 vaccination remained unchanged at 9. While myocarditis is an overall rare side effect after COVID-19 vaccination, it is currently the leading cause of myocarditis in our institution due to the large number of vaccinations applied over the last months. Contrary to myocarditis after vaccination, LGE and edema in myocarditis after COVID-19 often did not match or were confined to the RV-insertion site. Whether these cases truly represent myocarditis or a different pathological entity is to be determined in further studies.

PO-710-03 TEMPORAL AND SPATIAL EVOLUTION OF REVERSIBLE AND IRREVERSIBLE VENTRICULAR LESION BOUNDARIES PRODUCED BY PULSED ELECTRIC FIELD ABLATION

During pulsed electric field (PEF) ablation, electric pulses induce reversible (R) or irreversible (IR) injury on cardiac myocytes. Using triphenyl tetrazolium chloride (TTC) staining, we have reported that acute PEF ablation lesions show a dark central zone (DCZ, contraction band necrosis and hemorrhage) surrounded by pale boundary (PB, no mitochondrial activity, consistent with IR zone) and a hyperstained rim (HR, indicating enhanced mitochondrial activity) beyond the PB, indicating R zone. To assess histologically the spatial extent and temporal evolution of PEF ablation lesions in a swine model. A 7Fr catheter with a 3.5 mm ablation electrode (TactiCath, Abbott) was connected to a PEF generator (CENTAURI, Galaxy Medical) and positioned in RV and LV under EnSite guidance in 4 closed chest pigs. Biphasic PEF current (19 A, total duration 1.4 ms) was delivered between the ablation electrode and a skin patch at 50 ventricular sites at different target timepoints of <30 min, 1hr, 2hrs, 4hrs and 14 days after ablation. TTC was infused prior to animal sacrifice. Fig. The HR was initially greatest (<30 min) and gradually decreased over time while PB increased up to 4hr after ablation. The DCZ became evident only after 1hr and increased up to 4hr after ablation. At 14 days, ablation lesions show slightly smaller PB with no or minimal DCZ and HR. Histology showed fibrosis within the PB at 14 days, consistent with IR zone. TTC staining showed dynamic temporal and spatial evolution of the DCZ, PB and HR. The large initial HR zone indicates IR lesions are surrounded by relatively large R zone even 4hrs after ablation, suggesting the mechanism of transient conduction block during PEF ablation.

Impact of right ventricular pacing site on the subcutaneous ICD sensing-a step towards personalised device therapy?

Patients with an existing subcutaneous implantable cardiac defibrillator (S-ICD) may develop a pacing indication. When transvenous pacing is not feasible, combining an S-ICD and a leadless pacemaker (LP) can be a reasonable option. There are reports of concomitant use of both devices. However, the effect of pacing on the S-ICD sensing is not well studied. We hypothesise that pacing changes R and T-wave amplitudes, causing changes in R:T ratios as perceived by a S-ICD, increasing the risk for T wave oversensing (TWO) during paced rhythm with a subsequent risk of inappropriate shocks. This is a prospective study in patients undergoing electrophysiological studies. Participants were fitted with a Holter®, and the leads were placed to correspond to the vectors of an S-ICD. The right ventricle was paced at four positions for 10 beats each at 8mA/2ms. The Holter® traces were analysed, using two-way analysis of variance (ANOVA) to assess the effect of pacing on the R:T ratio. Forty-seven patients (age 56.02 ± 16.02, 72% male) were enrolled (81% structurally normal heart, 15% dilated cardiomyopathy, 2% ischaemic cardiomyopathy, and 2% adult congenital heart disease). Age, sex, and aetiology had no effect on the R:T ratio. Pacing caused significant changes in the R:T ratio. There was no significant difference in the R:T ratios between the pacing sites (p < 0.001). Pacing alters the R:T ratio significantly in most patients, theoretically increasing the risk for TWO and inappropriate shocks. Tailored programming for both devices is important for concomitant use of LPs and S-ICDs.

Acute hemodynamic impact of atrioventricular delay and left ventricular pacing vector programming in MultiPoint Pacing.

The benefits of cardiac resynchronization therapy (CRT) in heart failure patients have been shown to depend on device programming, particularly atrioventricular delay (AVD) and left ventricular (LV) pacing site selection. This study compared the hemodynamic AVD optimization for commonly used biventricular (BiV) and MultiPoint Pacing(MPP, Abbott) LV vector selection strategies. After de novo CRT-D (Abbott Quadra Assura MP) and quadripolar LV lead (Abbott Quartet) implant, acute LV pressure was measured across a range of AVDs (60-225 ms) in four pacing modes: BiV with most proximal cathode, BiV with most distal cathode, MPP using two cathodes with earliest and latest right ventricle (RV)-LV activation times, and MPP using two cathodes with maximal anatomical separation. Hemodynamic improvement was evaluated by changes in maximum LV pressure first-derivative versus RV pacing (ΔdP/dt). Twenty patients (64 years old, 68% male) completed the acute pacing protocol at six centers in China. Hemodynamic improvement versus RV pacing for BiV (proximal), BiV (Distal), MPP (electrical), and MPP (anatomical) was 22.1% ± 13.6%, 23.7% ± 13.4%, 24.5% ± 13.4%, and 25.1% ± 13.9%, respectively. The best MPP setting was marginally superior to the best BiV across all patients (25.8% ± 13.4% vs. 24.5% ± 13.1%, p = .040) and in the majority of patients (75.0% vs. 25.0%, p = .004). AVD programmed as little as 20 ms from optimum significantly reduced the ΔdP/dt benefit for all modes. The maximal hemodynamic improvement across AV delays in this population was greater with MPP than BiV. Furthermore, patient-specific AVD programming was critical in achieving the full hemodynamic response for all BiV and MPP modes.

On the Electrophysiology and Mapping of Intramural Arrhythmic Focus.

Conventional mapping of focal ventricular arrhythmias relies on unipolar electrogram characteristics and early local activation times. Deep intramural foci are common and associated with high recurrence rates following catheter-based radiofrequency ablation. We assessed the accuracy of unipolar morphological patterns and mapping surface indices to predict the site and depth of ventricular arrhythmogenic focal sources. An experimental beating-heart model used Langendorff-perfused, healthy swine hearts. A custom 56-pole electrode array catheter was positioned on the left ventricle. A plunge needle was placed perpendicular in the center of the grid to simulate arrhythmic foci at variable depths. Unipolar electrograms and local activation times were generated. Simulation models from 2 human hearts were also included with grids positioned simultaneously on the endocardium-epicardium from multiple left ventricular, septal, and outflow tract sites. A unipolar Q or QS complex lacks specificity for superficial arrhythmic foci, as this morphology pattern occupies a large surface area and is the predominant pattern as intramural depth increases without developing a R component. There is progressive displacement from the arrhythmic focus to the surface exit as intramural focus depth increases. A shorter total activation time over the overlying electrode array, larger surface area within initial 20 ms activation, and a dual surface breakout pattern all indicate a deep focus. Displacement from the focal intramural origin to the exit site on the mapping surface could lead to erroneous lesion delivery strategies. Traditional unipolar electrogram features lack specificity to predict the intramural arrhythmic source; however, novel endocardial-epicardial mapping surface indices can be used to determine the depth of arrhythmic foci.

Thrombus formation at the inflow cannula of continuous-flow left ventricular assist devices-A systematic analysis.

Despite numerous design iterations, thrombus formation at the inflow cannula of continuous-flow left ventricular assist devices remains an unsolved problem. We systematically investigated the impact of cannula surface on thrombus formation. Thrombus appearance was photographically documented in 177 explanted hearts with the polished (N=46) or sintered (N=131) inflow cannula of the Medtronic HeartWare™ HVAD™ System. Thrombus load was compared for both inflow cannula types. Mean thrombus length was correlated with protruding cannula length. Support duration and the extent of thrombus growth were examined. The prevalence of thrombi at the left ventricular entry site and at the sintered-to-polished transition zone was correlated with left ventricular geometry and hemodynamic parameters. Polished inflow cannulas showed a greater percentage and also a greater mean length of thrombus formation at the entry site than sintered cannulas (91.3% [Pol] vs. 36.7% [sTi]; p<0.0001; mean 7.6mm vs. 1.9mm; p<0.0001). A comparison of the early postoperative period (POD1-90) with long-term support (POD>90) showed an increase in thrombus length originating from the transition zone (1.96±3.41mm vs. 3.03±2.91mm; p=0.013). A sintered titanium surface at the entry site is crucial to enable anchoring of myocardial tissue to the cannula. As thrombus growth progresses on polished surfaces, a greater sintered length seems to be beneficial. After an initial three-month healing period, thrombus load appears to decline during prolonged support duration at the sintered entry site but not at the transition zone.

Safe closure of percutaneous ventricular access site for interventions in structural heart disease

Percutaneous transapical ventricular access for transcatheter procedures in structural heart disease is associated with an increased risk of bleeding from the access site. There are currently numerous suture and sutureless closure devices that are being investigated to close the transapical access site safely and effectively. Meticulous preprocedural planning with advanced imaging techniques is recommended to lay out the access path and closure of the transapical access site.

Septal versus apical pacing sites in permanent right ventricular pacing: The multicentre prospective SEPTAL-PM study

The optimal right ventricular pacing site for patients requiring pacemaker implantation for permanent atrioventricular block is a matter of debate. Long-term right ventricular apical pacing has been associated with left ventricular ejection fraction impairment and heart failure. Right ventricular septal pacing has been proposed as an alternative. The aim of this randomized prospective multicentre trial was to compare left ventricular remodelling and outcomes between right ventricular apical and septal pacing after mid-term follow-up. Patients requiring pacemaker implantation for high-degree atrioventricular block were enrolled and randomized in a 1:1 fashion to receive a right ventricular apical or septal lead. A total of 141 patients were included, 69 in the septal group and 72 in the apical group. Both groups exhibited similar left ventricular ejection fractions after 18 months of follow-up (septal 57.1±11.9% vs. apical 57.4±13.4%), and left ventricular ejection fraction variation was similar in the two groups at the end of follow-up (septal -1.5±13.2% vs. apical 0.3±13.3%). Additionally, left ventricular volume, quality of life and 6-minute walk distance were similar in the two groups. However, patients in the septal group were more likely to be asymptomatic, with a significantly lower concentration of N-terminal prohormone of brain natriuretic peptide. Lastly, lead position did not impact 18-month survival. Pacing from the right ventricular apex does not have any detrimental effect on left ventricular systolic function compared with septal pacing over an 18-month period.

Optimization of Left Ventricle Pace Maker Location Using Echo-Based Fluid-Structure Interaction Models.

IntroductionCardiac pacing has been an effective treatment in the management of patients with bradyarrhythmia and tachyarrhythmia. Different pacemaker location has different responses, and pacemaker effectiveness to each individual can also be different. A novel image-based ventricle animal modeling approach was proposed to optimize ventricular pacemaker site for better cardiac outcome.MethodOne health female adult pig (weight 42.5 kg) was used to make a pacing animal model with different ventricle pacing locations. Ventricle surface electric signal, blood pressure and echo image were acquired 15 min after the pacemaker was implanted. Echo-based left ventricle fluid-structure interaction models were constructed to perform ventricle function analysis and investigate impact of pacemaker location on cardiac outcome. With the measured electric signal map from the pig associated with the actual pacemaker site, electric potential conduction of myocardium was modeled by material stiffening and softening in our model, with stiffening simulating contraction and softening simulating relaxation. Ventricle model without pacemaker (NP model) and three ventricle models with the following pacemaker locations were simulated: right ventricular apex (RVA model), posterior interventricular septum (PIVS model) and right ventricular outflow tract (RVOT model). Since higher peak flow velocity, flow shear stress (FSS), ventricle stress and strain are linked to better cardiac function, those data were collected for model comparisons.ResultsAt the peak of filling, velocity magnitude, FSS, stress and strain for RVOT and PIVS models were 13%, 45%, 18%, 13% and 5%, 30%, 10%, 5% higher than NP model, respectively. At the peak of ejection, velocity magnitude, FSS, stress and strain for RVOT and PIVS models were 50%, 44%, 54%, 59% and 23%, 36%, 39%, 53% higher than NP model, respectively. RVA model had lower velocity, FSS, stress and strain than NP model. RVOT model had higher peak flow velocity and stress/strain than PIVS model. It indicated RVOT pacemaker site may be the best location.ConclusionThis preliminary study indicated that RVOT model had the best performance among the four models compared. This modeling approach could be used as “virtual surgery” to try various pacemaker locations and avoid risky and dangerous surgical experiments on real patients.

Clinical outcomes in patients with atrioventricular block undergoing pacemaker: 3-year follow-up.

Left ventricular function can be affected by chronic ventricular pacing. Different right ventricular (RV) pacing sites have shown heterogeneous clinical outcomes. We investigated these factors in patients receiving permanent pacemaker (PPM) implants. This multicenter, retrospective analysis of PPM use in South Korea, included all patients undergoing de novo transvenous PPM implantation for atrioventricular block from 2017 to 2019. Clinical characteristics, 12-lead electrocardiograms, echocardiography, and laboratory parameters were evaluated. Composite outcomes are defined by two coprimary endpoints: (1) hospitalizations and (2) cardiac death by heart failure during follow-up period. There were 167 patients (66 males; overall mean age 75.3 ± 11.9years), divided into two groups according to the pacing site: 83 apical RV (RVA) vs. 84 septal RV (RVS). There were no significant baseline differences. Paced QRS duration (pQRSd) increased with RVA (168.5 ± 20.1 vs. 159.1 ± 16.3ms; p < 0.001). Over a median 31-month follow-up, there were 15 hospitalizations and 2 deaths. More patients with RVA were hospitalized or died (16% vs. 5%, respectively; p = 0.049). In Cox proportional regression analysis, pQRSd (hazard ratio [HR] 1.046; 95% confidence interval [CI] 1.004-1.091; p = 0.033), and diastolic dysfunction (HR 7.343; 95% CI 2.035-26.494; p = 0.002) were independent predictors of composite clinical outcomes. RVS placement shortened the pQRSd and improved clinical outcomes. However, the determinants of these were pQRSd and diastolic dysfunction. Therefore, clinicians should try to shorten the pQRSd when implanting a PPM, and patients with diastolic dysfunction should be monitored intensively.

Beating heart implantation of transventricular artificial cordae: How can access site selection and leaflet insertion improve mitral regurgitation correction?

NeoChord-DS1000-System (NC) and The Harpoon-Mitral-Repair-System (H-MRS) are two trans-apical chordal implantation devices developed for the treatment of degenerative mitral valve (MV) regurgitation (DMR) either if as Fibroelastic-Deficiency (FED), Forma-Frusta (FF), or Barlow (B) presentation. The aim of this study is to evaluate some of the advantages and disadvantages of these two different devices by performing numerical simulation analyses focused on different transventricular access sites in all subsets of DMR presentations. By applying a novel approach for the development of patient-specific MV domains we worked out a set of numerical simulations of the artificial chordae implantation. Different leaflet insertions and ventricle access sites were investigated, and resulting contact-area (CA), tensioning-forces (F) and leaflet's stress (LS) were calculated. The analyses showed that: i) NC-approach maintains low LS when performed with a posterior access site and optimizes the overlap between the leaflets at the systolic peak; ii) H-MRS-system presents better results in case of a more anterior ventricular entry site; however, for FED prolapse large variation of F and LS with respect to NC-approach are found; iii) an accidental contact between artificial sutures and the anterior leaflet may occur when valve function is restored through an excessive anterior access site. Present findings set light on specific technical aspects of transapical off-pump chords implantation, either performed with NC and H-MRS systems and highlight the advantages and disadvantages proper to the two devices. Our study also paves the basis for a systematic application of computational methodology, in order to plan a patient-specific mini-invasive approach thus maximizing the outcomes.