Bundle Of His Research Articles

Experience with automated ECG interpretation in intraventricular conduction disturbances

In 2019, a new document called “National Guidelines. Functional Testing” was issued recommending the use of conventional electrocardiography terms for the description of intraventricular conduction disturbances associated with atrioventricular bundle branch blocks. The article describes the experience with the use of international ECG diagnoses of intraventricular conduction disturbances generated at an automated workplace of a functional testing specialist at P.V. Mandryka Central Military Clinical Hospital of the Ministry of Defense of the Russian Federation. ECG interpretation in patients with bundle branch blocks was based on the ACC/AHA Guidelines for Ambulatory ECG (2009), which proved to be of practical importance and clearly demonstrated the functions of the bundle of His branches and fascicles.

Non Selective his Bundle Pacing: As Physiological as S-HBP but Simpler and Faster

We have read with interest Dr. Burri’s Electrocardiographic Analysis for His Bundle Pacing at Implantation and Follow up [1]. A comprehensive guide to understand electrocardiographic (ECG) nuances of His Bundle Pacing (HBP) is presented in this review. The authors, with outstanding didactics, describe a well-organized analysis of challenging HBP electrocardiographic characteristics to confirm conduction tissue (selective or non-selective HBP) at implant and follow-up. Caught our interest, in particular, the paragraph where practical pacing characteristics and benefits of non-selective HBP pacing (NSHBP) are emphasized. In this context we would like to point out the statement that pacing “ventricular myocardium adjacent to the atrioventricular septum, near the His bundle can also result in NSHBP”. Above all, of paramount clinical importance, when Dr. Burri et al. conclude that “No significant differences in cardiac mechanical synchrony or clinical outcome have been found between SHBP and NSHBP”. Our group is in total agreement with these essential features, having abandoned SHBP many years ago by developing a very simple technique to place standard pacing leads in the para-Hisian area (Figure 1). Concordant with the authors, we understand that “With non-selective His bundle pacing (NS-HBP), the lead is usually positioned in the ventricle at a site where the His bundle (HB) is surrounded by or at proximity to myocardial tissue”. That is why we named “para-Hisian pacing”. In our daily practice, at the same time, to verify and prove physiological capture of the conduction system we monitor synchrony online by analyzing the ECG signal variance [8] (Synchromax®) [2].

Patient-Specific Computer Simulation to Predict Conduction Disturbance With Current-Generation Self-Expanding Transcatheter Heart Valves

BackgroundPatient-specific computer simulation may predict the development of conduction disturbance following transcatheter aortic valve replacement (TAVR). Validation of the computer simulations with current-generation devices has not been undertaken. MethodsA retrospective study was performed on patients who had undergone TAVR with a current-generation self-expanding transcatheter heart valve (THV). Preprocedural computed tomography imaging was used to create finite element models of the aortic root. Procedural contrast angiography was reviewed, and finite element analysis performed using a matching THV device size and implantation depth. A region of interest corresponding to the atrioventricular bundle and proximal left bundle branch was identified. The percentage of this area (contact pressure index [CPI]) and maximum contact pressure (CPMax) exerted by THV were recorded. Postprocedural electrocardiograms were reviewed, and major conduction disturbance was defined as the development of persistent left bundle branch block or high-degree atrioventricular block. ResultsA total of 80 patients were included in the study. THVs were 23- to 29-mm Evolut PRO (n = 53) and 34-mm Evolut R (n = 27). Major conduction disturbance occurred in 27 patients (33.8%). CPI (28.3 ± 15.8 vs. 15.6 ± 11.2%; p < 0.001) and CPMax (0.51 ± 0.20 vs. 0.36 ± 0.24 MPa; p = 0.008) were higher in patients who developed major conduction disturbance. CPI (area under the receiver operating characteristic curve [AUC], 0.74; 95% CI, 0.63-0.86; p < 0.001) and CPMax (AUC, 0.69; 95% CI, 0.57-0.81; p = 0.006) demonstrated a discriminatory power to predict the development of major conduction disturbance. ConclusionsPatient-specific computer simulation may identify patients at risk for conduction disturbance after TAVR with current-generation self-expanding THVs.

A computational framework for post-TAVR cardiac conduction abnormality (CCA) risk assessment in patient-specific anatomy.

Cardiac conduction abnormality (CCA)- one of the major persistent complications associated with transcatheter aortic valve replacement (TAVR) may lead to permanent pacemaker implantation. Localized stresses exerted by the device frame on the membranous septum (MS) which lies between the aortic annulus and the bundle of His, may disturb the cardiac conduction and cause the resultant CCA. We hypothesize that the area-weighted average maximum principal logarithmic strain (AMPLS) in the MS region can predict the risk of CCA following TAVR. Rigorous finite element-based analysis was conducted in two patients (Balloon expandable TAVR recipients) to assess post-TAVR CCA risk. Following the procedure one of the patients required permanent pacemaker (PPM) implantation while the other did not (control case). Patient-specific aortic root was modeled, MS was identified from the CT image, and the TAVR deployment was simulated. Mechanical factors in the MS region such as logarithmic strain, contact force, contact pressure, contact pressure index (CPI) and their time history during the TAVR deployment; and anatomical factors such as MS length, implantation depth, were analyzed. Maximum AMPLS (0.47 and 0.37, respectively), contact force (0.92N and 0.72N, respectively), and CPI (3.99 and 2.86, respectively) in the MS region were significantly elevated in the PPM patient as compared to control patient. Elevated stresses generated by TAVR devices during deployment appear to correlate with CCA risk, with AMPLS in the MS region emerging as a strong predictor that could be used for preprocedural planning in order to minimize CCA risk.

Experimental Findings and Clinical-Pathologic Correlation of Radiofrequency Catheter Ablation at the Left Ventricle Para-Hisian Region.

BackgroundCatheter ablation target at the site with large His activation in the left ventricle poses a high risk of atrioventricular (AV) block. We aimed to identify far-field (FF) and near-field (NF) His activation at left upper septum (LUS).MethodsThree-D mapping of the aortic root and left ventricle was performed in 12 dogs. Two sites located at either the base or apex of the triangle interposed between the hinges of the the noncornary coronary cusp (NCC) - right coronary cusp (RCC) were chosen for a single radiofrequency (RF) application. Bipolar and unipolar pacing with different outputs at both sites was attempted to discern NF and FF His activation.ResultsThe sites chosen for NF and FF ablation were located at the base and apex of the triangle, which were 8.03 ± 1.18 mm (group 1) and 3.42 ± 0.61 mm (group 2) away from the RCC-NCC junction. Lower A/V ratios were found in group 1. Pacing could not differentiate NF from FF His activation. In group 1, ablation resulted in III degree AV block in all 6 dogs, whereas neither PR prolongation nor AV block occurred in group 2. Pathologic examination of group 1 showed complete/partial necrosis of the His bundle (HB) and left bundle branch in all 6 dogs. In group 2, no necrosis of the HB was seen in the 6/6 dogs.ConclusionAnatomical localization in the triangle of RCC-NCC junction can help differentiate NF from FF His activation.

New right bundle branch block after selective HIS bundle pacing, Two methods for correction

HIS Bundle Pacing (HBP) is considered the most physiologic pacing technique as it generates a physiological activation of both ventricles through synchronous ventricular depolarization of His bundle– Purkinje conduction system. Permanent HBP and Atrioventricular Node (AVN) ablation in patients with heart failure and atrial fibrillation were found to have an improvement in cardiac function and reduction of left ventricular dimensions [1]. We present case of paroxysmal atrial fibrillation and atypical atrial flutter that underwent HBP and AVN ablation. The patient developed a Right Bundle Branch Block (RBBB) following his AVN ablation with widening of QRS duration to 148 msec. We managed to correct this and restore a narrow QRS by two different mechanisms: 1. Programming the Interventricular (VV) delay to 20 msec (His pacing first followed by septal RV pacing through a back-up lead, 2. Unipolar pacing of the HIS lead with different configuration. By both methods, QRS duration was reduced to 108-110 msec with restoration of physiologic biventricular pacing. To the best of our knowledge, this has not been reported before. Keywords: atrial fibrillation; his bundle pacing; ablate; pace.

Device treatment of heart failure

Background: The incidence of heart failure (HF) is rapidly increasing, introducing a significant burden and challenges in clinical practice. Non-pharmacological cardiac device therapy has been established as an essential component of optimal HF management, particularly for the prevention of sudden cardiac death and the improvement of HF symptoms, left ventricular (LV) systolic function, quality of life, and eventually survival.Current Concepts: Cardiac resynchronization therapy (CRT) can correct atrioventricular or inter/intraventricular dyssynchrony, thereby improving LV systolic function. Recently, the concept of CRT is being expanded, including His bundle (HB), HB-optimized LV, left bundle branch (LBB), and LBB optimized LV pacing CRTs. Newly introduced CRT approaches by stimulating the cardiac conduction system are expected to correct dyssynchrony better and consequently exhibit better CRT outcomes than the conventional biventricular pacing CRT. The current versions of implantable cardioverter-defibrillators (ICDs) or CRT devices can continuously monitor multiple biosignals. CRT/ICD can calculate a single index by combining these multiple bio-signal data for early detection of HF aggravation. Recently, subcutaneous and transvenous ICDs showed comparable safety and efficacy in HF patients. In drug-refractory HF patients without LV dyssynchrony, cardiac contractility modulation therapy provides some promising results.Discussion and Conclusion: Recent technological advancements have improved the efficacy and safety of cardiac device therapy. Therefore, cardiac device therapy should be used more actively to manage HF patients better.

Miniseries 2-Septal and paraseptal accessory pathways-Part I: The anatomic basis for the understanding of para-Hisian accessory atrioventricular pathways.

Although the anatomy of the atrioventricular conduction axis was well described over a century ago, the precise arrangement in the regions surrounding its transition from the atrioventricular node to the so-called bundle of His remain uncertain. We aimed to clarify these relationships. We have used our various datasets to examine the development and anatomical arrangement of the atrioventricular conduction axis, paying particular attention to the regions surrounding the point of penetration of the bundle of His. It is the areas directly adjacent to the transition of the atrioventricular conduction axis from the atrioventricular node to the non-branching atrioventricular bundle that constitute the para-Hisian areas. The atrioventricular conduction axis itself traverses the membranous part of the ventricular septum as it extends from the node to become the bundle, but the para-Hisian areas themselves are paraseptal. This is because they incorporate the fibrofatty tissues of the inferior pyramidal space and the superior atrioventricular groove. In this initial overarching review, we summarize the developmental and anatomical features of these areas along with the location and landmarks of the atrioventricular conduction axis. We emphasize the relationships between the inferior pyramidal space and the infero-septal recess of the subaortic outflow tract. The details are then explored in greater detail in the additional reviews provided within our miniseries. Our anatomical findings, described here, provide the basis for our concomitant clinical review of the so-called para-Hisian arrhythmias. The findings also provide the basis for understanding the other variants of ventricular pre-excitation.

Miniseries 1-Part I: the Development of the atrioventricular conduction axis.

Despite years of research, many details of the formation of the atrioventricular conduction axis remain uncertain. In this study, we aimed to clarify the situation. We studied three-dimensional reconstructions of serial histological sections and episcopic datasets of human embryos, supplementing these findings with assessment of material housed at the Human Developmental Biological Resource. We also examined serially sectioned human foetal hearts between 10 and 30 weeks of gestation. The conduction axis originates from the primary interventricular ring, which is initially at right angles to the plane of the atrioventricular canal, with which it co-localizes in the lesser curvature of the heart loop. With rightward expansion of the atrioventricular canal, the primary ring bends rightward, encircling the newly forming right atrioventricular junction. Subsequent to remodelling of the outflow tract, part of the primary ring remains localized on the crest of the muscular ventricular septum. By 7 weeks, its atrioventricular part has extended perpendicular to the septal parts. The atrioventricular node is formed at the inferior transition between the ventricular and atrial parts, with the transition itself marking the site of the penetrating atrioventricular bundle. Only subsequent to muscularization of the true second atrial septum does it become possible to recognize the definitive node. The conversion of the developmental arrangement into the definitive situation as seen postnatally requires additional remodelling in the first month of foetal development, concomitant with formation of the inferior pyramidal space and the infero-septal recess of the subaortic outflow tract.

Mitral Annulus Calcification and Cardiac Conduction Disturbances: A DANCAVAS Sub-study.

BACKGROUNDDue to its location very close to the bundle of His, mitral annulus calcification (MAC) might be associated with the development of atrioventricular (AV) conduction disturbances. This study assessed the association between MAC and AV conduction disturbances identified by cardiac implantable electronic device (CIED) use and electrocardiographic parameters. The association between MAC and traditional cardiovascular risk factors was also assessed.METHODSThis cross-sectional study analyzed 14,771 participants, predominantly men aged 60–75 years, from the population-based Danish Cardiovascular Screening trial. Traditional cardiovascular risk factors were obtained. Using cardiac non-contrast computed tomography imaging, MAC scores were measured using the Agatston method and divided into absent versus present and score categories. CIED implantation data were obtained from the Danish Pacemaker and Implantable Cardioverter Defibrillator Register. A 12-lead electrocardiogram was available for 2,107 participants. Associations between MAC scores and AV conduction disturbances were assessed using multivariate regression analyses.RESULTSMAC was present in 22.4% of the study subjects. Participants with pacemakers for an AV conduction disturbance had significantly higher MAC scores (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.01–1.23) than participants without a CIED, whereas participants with a CIED for other reasons did not. Prolonged QRS-interval was significantly associated with the presence of MAC (OR, 1.45; 95% CI, 1.04–2.04), whereas prolonged PQ-interval was not. Female sex and most traditional cardiovascular risk factors were significantly associated with high MAC scores.CONCLUSIONSMAC was associated with AV conduction disturbances, which could improve our understanding of the development of AV conduction disturbances.

Can permanent His Bundle Pacing be safely started by operators new to this technique? Data from a multicenter registry

Right ventricular pacing (RVP) induces ventricular asynchrony in patients with normal QRS and increases the risk of heart failure and atrial fibrillation on long-term. His bundle pacing (HBP) is a physiological alternative to RVP, and could overcome its drawbacks. Recent studies assessed feasibility and safety of HBP in expert centers with a vast experience of this technique. These results may not apply to less experienced centers. We aim to evaluate feasibility and safety of permanent HBP performed by physicians who are new to this technique. We included all patients who underwent pacemaker implantation with attempt of HBP in 3 hospitals between September 2017 and January 2020. Indication for HBP was left to operators’ discretion. All the operators were new for HBP. His Bundle (HB) electrical parameters were recorded at implant, 3- and 12-month follow-up. HBP was successful in 141 of 170 patients (82.9%); selective HBP was obtained in 96 patients and nonselective HBP in 45. The mean procedure and fluoroscopy durations were 67.0 ± 28.8 min, and 7.3 ± 8.1 min (3.1 ± 4.1 Gy.cm 2 ), respectively. The mean HB paced QRS duration was 106 ± 18 ms. The mean HB capture threshold was 1.29 ± 0.77 V and did not increase at 3- and 12-month follow-up. Ventricular lead revision was required in 5 patients. Our results showed a rapid technical learning allowing a high procedure success rate (89.8%) after 15 procedures ( Fig. 1 ). HBP performed by operators new to this technique appeared feasible and safe. This should encourage HBP to be performed in patients expected to experience high RVP burden.

Histological Features of the Atrioventricular Conduction System in Cats with High-Grade Atrioventricular Block

The histopathological features of the atrioventricular (AV) conduction system of nine cats with high-grade atrioventricular block (H-AVB) were compared with those of 22 cases of third-degree atrioventricular block (3-AVB). All nine H-AVB cats had experienced syncopal attacks of variable severity and had been diagnosed electrocardiographically. The AVB, which was permanent in all cases, had been observed for 15-1,981 days (average 663 days) before death. Histological examination of the AV conduction system revealed moderate (25-50%) or severe (>50%) loss of conduction fibres associated with fibrous replacement in the regions of the branching portion of the AV bundle and the upper portion of the left bundle branch in almost all of the H-AVB cases and in all the 3-AVB cases. Comparison of lesion severity in each region in the H-AVB and 3-AVB cases revealed that the branching portion of the AV bundle was less severely affected in the H-AVB cases. This finding might explain why the H-AVB cases had intermittent block of AV conduction while the 3-AVB cats had permanent block.

During Early VF in Rabbit Hearts, His Bundle Pacing is Less Effective Than Working Myocardial Pacing in Modulating Left Ventricular Activation Rates.

The potential of pacing and capturing the His-Purkinje system (HPS) to synchronize VF wavefronts is not known even though the HPS is thought to be electrically linked during VF. In this study the effect of selective His Bundle (HB) pacing was compared with nearby working myocardial (WM) pacing on the left ventricular (LV) endocardial activation rates. Rabbit hearts (n = 9) were explanted and Langendorff perfused. Electrodes directly on the HB were identified and paced subsequently using an electrode array. The WM was paced through a silver wire inserted in the right ventricular septal wall. After VF was induced, the HB was paced at rates faster than the intrinsic HB activation rate (n = 18 episodes) and also at rates faster than the LV activation rate (n = 16). A basket array inserted in the LV was used to record electrograms before and during each pacing episode. Activation rates at five LV electrodes each from the earliest and latest activating sinus rhythm regions were analyzed before and during pacing. Both HB and WM pacing reduced LV activation rates during pacing, but WM pacing was more effective (p < 0.005). WM pacing events were more effective (p < 0.05) in reducing LV activation rates than HB pacingin episodes which were faster than LV activation rates. This study provides evidence that during early VF in rabbit hearts, the HPS cannot be driven to effectively modulate the LV activation rates.

El sistema especializado de conducción eléctrico del corazón. Los nodos del corazón y el sistema His-Purkinje. Sustrato anatómico de las vías accesorias

The specialized electrical conduction system of the heart. The heart nodes and the His-Purkinje system. Anatomical underpinnings of the accessory pathwaysThe muscular architecture of the heart myocardium is mainly composed of muscle cells, or cardiomyocytes, that are responsible for myocardial contraction as well as an interstitial space with a component of collagen-producing cells, or fibroblasts, surrounded by an extracellular matrix of connective tissue. Small cell groups predominantly located in the atria have neuroendocrine characteristics. In order to activate of the striated myocardium and excitation-contraction coupling through transmembrane action potential, the presence of specialized cells of the specific conduction system is necessary. The process and sequence of activation of the heart chambers occurs through the specific conduction system and is modulated by sympathetic and parasympathetic fibers of the neurovegetative system, which exercise autonomous control of it.The atrioventricular conduction system is composed of specialized myocytes and has an atrial component: the sinoatrial node and atrioventricular node, which are in contact with the atrial myocardium. Next, the bundle of His crosses the central fibrous body and divides into two bundles or branches—the left and the right—which branch into the ventricles, forming what is known as Purkinje fibers. The bundle of His and its branches are surrounded by a layer of connective tissue that is lost in the Purkinje fibers, allowing them to establish direct contact with the ventricular myocardium. Detailed knowledge of the specific conduction tissue is necessary to understand normal heart rhythm and the anatomical and electrical underpinnings that constitute heart arrhythmias.

Taquicardias supraventriculares

Supraventricular arrhythmias are a set of tachycardias or rapid arrhythmias in which any of the structures located above the bundle of His is essential for its onset and maintenance. By definition, they are rapid rhythms, with a heart rate above 100 bpm. They have a good prognosis, although on occasion they can have an incessant nature and favor the development of tachycardiomyopathy. The term supraventricular tachycardia (SVT) refers to a group of supraventricular arrhythmias which excludes atrial fibrillation, as it is an entirely different entity.

Non-invasive Characterization of Human AV-Nodal Conduction Delay and Refractory Period During Atrial Fibrillation.

During atrial fibrillation (AF), the heart relies heavily on the atrio-ventricular (AV) node to regulate the heart rate. Thus, characterization of AV-nodal properties may provide valuable information for patient monitoring and prediction of rate control drug effects. In this work we present a network model consisting of the AV node, the bundle of His, and the Purkinje fibers, together with an associated workflow, for robust estimation of the model parameters from ECG. The model consists of two pathways, referred to as the slow and the fast pathway, interconnected at one end. Both pathways are composed of interacting nodes, with separate refractory periods and conduction delays determined by the stimulation history of each node. Together with this model, a fitness function based on the Poincaré plot accounting for dynamics in RR interval series and a problem specific genetic algorithm, are also presented. The robustness of the parameter estimates is evaluated using simulated data, based on clinical measurements from five AF patients. Results show that the proposed model and workflow could estimate the slow pathway parameters for the refractory period, and ΔRSP, with an error (mean ± std) of 10.3 ± 22 and −12.6 ± 26 ms, respectively, and the parameters for the conduction delay, and , with an error of 7 ± 35 and 4 ± 36 ms. Corresponding results for the fast pathway were 31.7 ± 65, −0.3 ± 77, 17 ± 29, and 43 ± 109 ms. These results suggest that both conduction delay and refractory period can be robustly estimated from non-invasive data with the proposed methodology. Furthermore, as an application example, the methodology was used to analyze ECG data from one patient at baseline and during treatment with Diltiazem, illustrating its potential to assess the effect of rate control drugs.

The relationship between anatomy and electrical parameters in His bundle pacing

Abstract Background The relationship between anatomy and electrical parameters of His bundle (HB) pacing has not been extensively studied. Purpose To characterize the anatomical location of the HB lead tip and its relationship with acute electrical parameters. Methods Consecutive patients who underwent HB lead implantation, guided by standard fluoroscopy and electrophysiology, were prospectively enrolled. The relationship between HB lead tip and tricuspid valve plane (TVP) was assessed with post-procedure transthoracic echocardiography. Results Twenty-five patients were studied. In 11 patients (44%), the HB lead tip did not cross the TVP (A group): in 7 cases it was screwed in the right atrium at a mean distance of −6.1 mm from the TVP and, in 4 cases, at the level of the tricuspid annulus. In the remaining 14 patients (56%), the lead tip crossed the TVP (V group): it was screwed in the right ventricle at a mean distance of 9.3 mm from the TVP. A and V groups had comparable HB capture thresholds (1.6±1 V vs 1.7±0.7 V, 1 ms pulse-width; p=0.66); selective HB capture was significantly more represented in the A group (91% vs 21%; p=0.001). Significantly higher R-wave amplitudes were seen in the V group (6.7±3 vs 2.5±1.7 mV; p=0.0004), and they positively correlated with the distance from the TVP (p=0.0038). Atrial oversensing was never observed. Conclusion In a consecutive cohort of HBP recipients, the rate of patients who had an effective HB capture in the atrium was substantial and was characterized by different electrophysiological properties than in the ventricle. Funding Acknowledgement Type of funding sources: None.

Selectra 3D- guided conduction system pacing: single-center experience

Abstract Background Conduction system pacing (CSP)is becoming increasingly popular thanks to the ability to both maintain physiological electrical activation in patients with narrow QRS and restore ventricular synchrony in patients with bundle branch block (BBB). The Selectra3D introducer is a new tool able to support the correct positioning and screwing of the catheter on the bundle of His (HBP) or on the left branch (LBBP). It does exist in 3 different shapes: S, M, L (Fig. 1) based on the radius of main curvature. The internal diameter of 7.3 Fr allows it to support both the 3830 lumen-less catheter historically used for CSP, as well as standard 6Fr stylet-driven leads. Objective To evaluate the effectiveness of the Selectra3D introducer for CSP (including both HBP and LBBP), considering the procedural success rate and the lead stability (stability of electrical parameters or need for implant revision) in the medium-term follow-up. Methods and results The Selectra3D introducer was used in 56 patients' candidates for CSP (mean age 80±6 years). Pacing indications included A-V block in 21 patients, AF with slow ventricular response in 9 patients; SND in 8 patients and HF and severe ventricular dysfunction in 18 patients (of which 4 were PICM). The mean baseline EF was 40±15%. A PM was implanted in 40 patients and an ICD in 16. A standard stylet-driven lead was used in 48 cases, a fixed exposed screw lead was used in 8 patients. HBP was obtained in 21 cases and LBBP in 30 cases, while in 5 cases (8.9%) neither HBP nor LBBP could be obtained. Implants were performed via a left-sided approach in 55 cases and a right-sided approach in 1 case. The baseline QRS duration was 144±38 ms and the paced QRS duration was 118±21 ms. The electrical parameters were optimal with sensing 8.7±8 mV; impedance 625±276 ohm; threshold 1±0.5 V. During follow-up, 2 lead dislodgement (3.9%) (1 HBP and 1 LBBP) were recorded, both within 7 days after implantation. All the others showed stability of the electrical parameters at a mean follow-up of 8.4±4.2 months. Conclusions The new Selectra3D introducer supports effectively and safely the lead implant on conduction system catheters (HBP and LBBP), allowing the implant of both exposed fixed screw leads and standard stylet-driven leads, leading to procedural success&amp;gt;90%. The electrical parameters were optimal at implantation and remained stable during follow-up. Funding Acknowledgement Type of funding sources: None. Figure 1

Nationwide prevalence and characteristics of transthyretin amyloid cardiomyopathy in Sweden

ObjectiveTransthyretin amyloid cardiomyopathy (ATTR-CM) is a rare, progressive and fatal condition caused by deposition of transthyretin amyloid fibrils in the heart. This study aims to identify all patients diagnosed with...

Retrograde penetration pacing into the conduction system as an alternative approach of his-bundle pacing

BackgroundThe optimal right ventricular (RV) pacing site during pacemaker implantation is still unclear due to left ventricular (LV) dyssynchrony by traditional RV pacing. His-bundle (HIS) pacing has achieved narrow QRS and maintained LV synchrony but high failure rate. RV septal pacing occasionally has QRS waveform with wide and narrow component in the early and late phase, respectively, and maintains LV synchrony, reflecting the normal conduction system. We aimed to define this QRS waveform as retrograde penetration pacing into the conduction system (RPP-CS) and compared its effect on LV synchrony as an alternative approach of HIS pacing. Methods and ResultsWe enrolled 42 patients with atrio ventricular block (AVB) or bradycardia atrial fibrillation (AF) requiring pacemaker implantation (RPP-CS, n = 27; no RPP-CS, n = 15). Baseline characteristics were similar between the groups. RPP-CS was observed in 96% and 26% of the RV septum and apex area, respectively. RPP-CS had a significantly shorter QRS width (p < 0.001). The frequency of maintaining LV synchrony was significantly higher in RPP-CS (67% vs. 20%, p = 0.003). The QRS interval's optimal cut-off value during RPP-CS was 132 ms for prediction of LV synchrony (sensitivity 83%, specificity 89%, positive predictive value 94%, and negative predictive value 73%). During RPP-CS, shorter QRS intervals (QRS ≤ 132 ms) had better postoperative LV ejection fraction than longer intervals (p < 0.001). ConclusionsRPP-CS, especially with short QRS intervals (≤132 ms), had a high frequency of LV synchrony, maintained postoperative cardiac function, and may be an adequate first-line RV pacing site strategy for AVB or bradycardia AF as an alternative approach of HIS pacing.