Bundle Of His Research Articles

Bilateral impact of cardiorenal relationships in the nephrotic syndrome.

To study and analyze the cardiorenal relationships in nephrotic syndrome, taking into account sex differences. A total of 272 patients with nephrotic syndrome (NS) aged 16 to 65 years were examined. All patients underwent general clinical examination, electro-and echocardiography, assessment of peripheral and biochemical blood counts. NS was determined with daily proteinuria of more than 3.5 g/1.73 m2 per day, hypoalbuminemia (albumin less than 30 g/l) and hyperlipidemia (total cholesterol more than 5.1 mmol/l). The duration of the National Assembly ranged from 3 months or more. Depending on the gender, the total sample (n=272) was divided into two subgroups: the 1st subgroup - patients with female NS (n=88), the 2nd subgroup - males with NS (n=184). The mean systolic, diastolic, pulse and mean arterial pressure (BP) were significantly higher in male NS patients (p<0.05). Supraventricular and ventricular ectopic activity was significantly more common in males. In the subgroup of women with NA, sinus tachycardia was significantly more frequently detected, a slowing down of the impulse conduction along the bundle of His, a violation of the processes of repolarization of the LV (p<0.05). The final systolic and diastolic sizes of the left ventricle (LV), the thickness of the interventricular septum and the posterior wall of the left ventricle, the diameter of the aorta, the longitudinal size of the left atrium and the right ventricle were significantly larger in the group of males with NA. Significantly lower concentrations of hemoglobin, hematocrit, erythrocyte counts were observed in the subgroup of females with NS compared with men (p<0.05). In the cohort of men with HC, there was a significant decrease in the content of total serum protein (44.8±11.0 g/l versus 49.2±11.2 g/l; p=0.003) as compared with females. In the male subgroup of HC, serum creatinine concentration [97 (81;143) mmol/l versus 86 (68;123) mmol/l; p=0.005] and the degree of daily protein excretion [6,490 (4,865;9,661) g versus 5,585 (4,168;7,625) g; p=0.034] with urine were significantly higher compared with the female subgroup (Table 2). At the same time, in the cohort of men with HC, there was a significant decrease in the calculated GFR [62.3 (46.2; 114.9) ml/min versus 87.0 (67.7;127.5) ml/min; p=0.002]. In case of NS in females, factors of deterioration of cardiorenal interrelations are anemia, sinus tachycardia, slowing down of impulse conduction along the bundle of His. Whereas in the NA subgroup of men, negative factors of cardiorenal interrelations are hypoproteinemia, increased systolic, diastolic, pulse and mean blood pressure, creatinine concentration and daily proteinuria, which was accompanied by a decrease in glomerular filtration rate and an increase in the linear dimensions of the heart.

P2275Left-sided deviation and fibrous-fatty infiltration of the right bundle branch in the elderly: implication for transcatheter aortic valve implantation (TAVI) procedure

Abstract Introduction Permanent and irreversible damage to the conduction tissue is one of the most common complications of TAVI. Detailed knowledge of the anatomy of the atrioventricular (AV) bundle is crucial to minimize the potential for injury to the His bundle branch block or complete AV block. Purpose Preexisting anatomic location and damage of the right bundle branch (RBB) may have important unrecognized clinical implications. Methods The myocardial arrangement and the presence of fibrous and fatty tissue infiltration of the AV conduction axis and right bundle branch were examined by dissection techniques and histological sections in 57 structurally normal human heart specimens (48 males, 77±7 years). Results The AV conduction axis enters the AV component of the membranous septum and is encircled by the fibrous tissue of the central fibrous body. The AV bundle is divided in a non-branching portion and a branching portion. After a short distance of the non-branching component along the septal crest, the RBB arises at the end of the branching portion of the conduction axis and is located superficially in the muscular ventricular septum. The RBB takes off from the bundle at the level of origin of the superior fascicle of the left bundle, passing then through the thickness of the ventricular septum to emerge beneath the medial papillary muscle of the tricuspid valve. In 22 hearts (49%) in which we found to have a relatively left-sided deviation of the AV bundle in relation to the interventricular membranous septum the RBB runs intramyocardial along the muscular interventricular septum. In the remaining 51% of the hearts the RBB runs subendocardially in the crest of the interventricular muscular septum. We found connective tissue and fatty infiltration along the right bundle branch in 23 hearts (40%) from its origin to its distal part. A significant correlation was found between age and the presence of RBB fibrosis (85% of hearts from individuals with age &gt;80 years). These 2 conditions may make the RBB very vulnerable to self-expanding aortic valves during or after TAVI (figure). RBB and its critical region Conclusions The presence of an intramyocardial location of the RBB with a lef-sided deviation and the fibro-fatty infiltration found in the mayority of senescent hearts are relevant anatomic determinants that may increase the risk of complete AV block following a TAVI procedure.

P6014The variable location of the atrioventricular conduction axis. Implications for permanent and safe His bundle pacing

Abstract Background/Introduction The deleterious effects of long-term RV apical pacing have been well recognized. Permament His bundle (HB) pacing has emerged as a promising technique for patients who need ventricular pacing. Purpose To describe the anatomy of the HB region and its variations for successfully approaching HB pacing in a safer and more efficient way and to understand selective vs non-selective HB pacing and to avoid permanent damage to it. Methods In 57 structurally normal human heart specimens (48 males, 77±7 years) we examined by dissection techniques and histological sections the course of the penetrating and non-branching His bundle in relation with the membranous septum and the tricuspid valve (TV) annulus. We correlated these anatomic findings with a series of angiographic studies in 60 patients (47% males, 45±16 years old) by recording the largest His electrogram sites within the limits of the triangle of Koch (TK) and the plane of the TV. Results The membranous septum is divided by the attachment on its right side of the septal leaflet of the tricuspid valve into atrioventricular (AV) and interventricular components. The AV component of the membranous septum forms the anterosuperior apex of the TK and showed in cadaveric hearts variable dimensions in length (4.6±1.5 mm, range 1–9 mm). The AV node becomes the His bundle as the AV conduction axis enters the AV component of the membranous septum and is encircled by the fibrous tissue of the central fibrous body in 100% of hearts with none of them having a “naked” entrance to it. In 30 hearts (53%) the HB penetrates the AV membranous septum at the apex of the TK at the hinge point of the septal leaflet of the TV near its commissure with the anterosuperior leaflet. However in 47% of cases the HB crossed the fibrous tissue of the central fibrous body in a lower position in the medial area of the paraseptal right atrial region of the TK with a mean distance to the AV membranous septum of 4±1.4 mm (range 1.5–8 mm) above and behind the TV annulus. These findings correlate with those obtained in patients in which the site of recording of the largest His bundle deflection does not always coincide with the anterosuperior vertex of the triangle as judged angiographically. In 51% of patients the site of the largest His bundle electrograms was found in the medial area of the triangle above (posterior-inferior) the TV annulus while in 49% of patients the His was recorded at the same level (15%) or below (anterior-inferior) the TV annulus (34% of patients) (figure). Histology of HB and catheter locations Conclusions Knowledge of the marked variability in the location of the AV conduction bundle within the paraseptal right atrial region is crucial for approaching permanent HB pacing. An anterior-inferior and ventricular HB location could yield to restriction of the septal leaflet of the tricuspid valve if a lead is to be deployed in the area.

P6015Histological pattern of penetrating His bundle division: implications for atrioventricular conduction damage during and following transcatheter aortic valve implantation

Abstract Background Severe damage to the atrioventricular conduction system is one of the most common complications of transcatheter aortic valve implantation (TAVI) and can be linked to important comorbidity, increased healthcare expense, need for long-term monitoring and pacemaker implantation. Purpose To provide a detailed description of the His bundle (HB) arrangement within the left ventricular outflow tract. Methods We examined by dissection techniques and histological sections the course of the AV conduction axis (penetrating, non-branching and branching HB) in relation with the membranous and muscular interventricular septum in 57 structurally normal human heart specimens (48 males, 77±7 years) Results The AV conduction axis is located along the inferior edge of the membranous septum (MS). The MS is divided into AV and interventricular components and is located at the base of the interleaflet triangle between the right and non-coronary leaflets of the aortic valve. The conduction axis enters the AV component of the MS and is encircled by the fibrous tissue of the central fibrous body to reach the left ventricular outflow tract. The MS showed in cadaveric hearts variable dimensions in length (4.6±1.5 mm) with a range bewteen 1 to 9mm. In 17.5% of specimens the MS length was ≤2 mm. After penetrating the AV membranous septum it has a non-branching component that in 85.5% of cases runs only for a short distance (1–3 mm) along the septal crest before giving rise to the fascicles of the left bundle (LB) on the septal surface (Type A). The most anterior fibers of the LB originate at the end of the branching portion located underneath the inferior edge of the MS. In 5 hearts (9%) the HB division was found before it reached the interventricular MS (Type B) and in 3 cases (5.5%)2–3.5 mm distal to the crest (Type C). 22 hearts (49%) were shown to have a relatively left-sided deviation of the AV bundle with the anterior part of the bundle closely related to the nadir of attachment of the right coronary leaflet of the aortic valve. In the remaining 51% of hearts, the bundle coursed centrally or with a right-sided deviation. The HB measures were (mm, mean±SD (range)): length: 3±0.6 (2–4.5), width: 3.7±1.4 (2.5–5.6), thickness: 1.4±0.5 (0.5–2.2), HB to endocardium: 0.7±0.3 (0.2–1.5). His bundle position types Conclusions A shorter membranous septum length, the variable HB dimensions and the left-sided deviation of the AV conduction axis are extremely relevant anatomic features that are linked to the frequent injury to the HB branch or complete AV block following TAVI.

A CASE OF RARE PRE-EXCITATION IN HYPERTROPHIC CARDIOMYOPATHY: IDENTIFYING A NEW LINK

SESSION TITLE: Case Report Semifinalists 6 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Fasciculoventricular bypass tract (FVBT) is rarely seen in patients with hypertrophic obstructive cardiomyopathy (HOCM). Mutation in the PRKAG2 gene has been established in such patients. We present a case report with an unusual variant of pre-excitation involving the fasciculoventricular pathway in a patient with HOCM identifying a new mutation on genetic testing. CASE PRESENTATION: A 21-year-old male with a past medical history of severe HOCM and bipolar disorder presented with substernal chest pain radiating to both arms, in the setting of an altercation. He was on metoprolol 50 mg daily for severe HOCM. Family history was significant for sudden cardiac death of his mother in her forties. His physical examination was significant for tachycardia. His admission EKG revealed Wolff-Parkinson-White syndrome (WPW) type B pattern, with no ST segment or T wave changes concerning for ischemia and cardiac enzymes were normal. Echocardiogram revealed a left ventricular outflow tract gradient of >36 mm Hg, severe septal hypertrophy of 2.6 cm with normal left ventricular function. On the second night of hospitalization, the patient had an asymptomatic run of wide QRS complex tachycardia for one and a half minutes. Review of the telemetry strips determined rhythm to be atrial fibrillation with pre-excitation. He underwent an electrophysiological (EP) study, which revealed a fasciculoventricular pathway without any inducible arrhythmia, and hence no ablation could be performed. He was offered an implantable cardioverter defibrillator (ICD) which he declined. On further genetic studies, it was found that the patient has a mutation in MYH7 gly741 trp gene. Metoprolol was continued and he was discharged with EP follow up. DISCUSSION: Fasciculoventricular pathway (FVP) is a very rare form of pre-excitation, with an incidence of 1.2% to 5.1% of all pre-excitation syndromes; resulting from an accessory connection between either the bundle of His or the fascicles and the ventricle. Familial hypertrophic cardiomyopathy displays autosomal dominant inheritance with incomplete penetration of defective genes and so does some of the pre-excitation syndromes like WPW. In the literature, only a gene mutation on chromosome 7q3 (PRKAG2 gene) has been described in familial HOCM coexisting with preexcitation syndrome to date. To our knowledge, this is the first case report identifying MYH7 gene mutation in a patient with coexisting HOCM and FVBT. Although there is one reported case of MYH7 gene mutation in HOCM with WPW. Since this is the only case showing a link between the MYH7 mutation and HOCM with FVBT, we cannot conclude whether the observed mutation is a common cause for both diseases, or this patient presents an incidental co-occurrence of HOCM (caused by the MYH7 mutation) and FVBT. CONCLUSIONS: Further investigations need to be done to establish MYH7 mutation as a link between HOCM and pre-excitation syndromes. Reference #1: Andrea Giuseppe Porto, MD, Francesca Brun, MD, Giovanni Maria Severini, PhD Pasquale Losurdo, MD, Enrico Fabris, MD, Matthew R.G. Taylor, MD, PhD, Luisa Mestroni, MD, Gianfranco Sinagra, MD. Clinical Spectrum of PRKAG2 Syndrome. Circ Arrhythm Electrophysiol. 2016 Jan; 9(1): 10.1161/CIRCEP.115.003121 e003121. https://doi.org/10.1161/CIRCEP.115.003121 Reference #2: Suzuki T, Nakamura Y, Yoshida S, Yoshida Y, Shintaku H. Differentiating fasciculoventricular pathway from Wolff-Parkinson-White syndrome by electrocardiography. Heart Rhythm. 2014;11:686– 690. https://doi.org/10.1016/j.hrthm.2013.11.018. Reference #3: Bobkowski W, Sobieszczańska M, Turska-Kmieć A, Nowak A, Jagielski J, Gonerska M, Lebioda A, Siwińska A. Mutation of the MYH7 gene in a child with hypertrophic cardiomyopathy and Wolff-Parkinson-White syndrome. J Appl Genet. 2007;48(2):185-8. DISCLOSURES: No relevant relationships by Kushani Gajjar, source=Web Response No relevant relationships by Abhas Khurana, source=Web Response No relevant relationships by Gaurav Manek, source=Web Response No relevant relationships by Anand Muthu Krishnan, source=Web Response no disclosure on file for Vidya Nadig

Cardiovascular Risk in Fatty Liver Disease: The Liver-Heart Axis-Literature Review.

According to the World Health Organization, cardiovascular disease (CVD) remains the leading cause of death worldwide, accounting for approximately 18 million deaths per year. Nevertheless, the worldwide prevalence of metabolic diseases, such as type 2 diabetes mellitus, obesity, and non-alcoholic fatty liver disease (NAFLD), also known to be common risk factors for CVD, have dramatically increased over the last decades. Chronic alcohol consumption is a major cause of chronic liver diseases (CLD) as well as being a major health care cost expenditure accounting for the spending of tremendous amounts of money annually. NAFLD has become one of the major diseases plaguing the world while standing as the most common cause of liver disease in the Western countries by representing about 75% of all CLD. Currently, the most common cause of death in NAFLD remains to be CVD. Several mechanisms have been suggested to be responsible for associating FLD with CVD through several mechanisms including low-grade systemic inflammation, oxidative stress, adipokines, endoplasmic reticulum stress, lipotoxicity and microbiota dysbiosis which may also be influenced by other factors such as genetic and epigenetic variations. Despite of all this evidence, the exact mechanisms of how FLD can causally contribute to CVD are not fully elucidated and much remains unknown. Moreover, the current literature supports the increasing evidence associating FLD with several cardiovascular (CV) adverse events including coronary artery disease, increased subclinical atherosclerosis risk, structural alterations mainly left ventricular hypertrophy, increased epicardial fat thickness, valvular calcifications including aortic valve sclerosis and mitral annular calcification and functional cardiac modifications mainly diastolic dysfunction in addition to cardiac arrhythmias such as atrial fibrillation and ventricular arrythmias and conduction defects including atrioventricular blocks and bundle branch blocks. Patients with FLD should be evaluated and managed accordingly in order to prevent further complications. Possible management methods include non-pharmacological strategies including life style modifications, pharmacological therapies as well as surgical management. This review aims to summarize the current state of knowledge regarding the pathophysiological mechanisms linking FLD with an increased CV risk, in addition to associated CV adverse events and current management modalities.

In This Issue

In This Issue

In This Issue

HomeCirculation ResearchVol. 125, No. 4In This Issue Free AccessIn BriefPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessIn BriefPDF/EPUBIn This Issue Ruth Williams Ruth WilliamsRuth Williams Search for more papers by this author Originally published1 Aug 2019https://doi.org/10.1161/RES.0000000000000290Circulation Research. 2019;125:367is related toMetabolic Syndrome Exacerbates Pulmonary Hypertension due to Left Heart DiseaseSingle-Cell Transcriptomics Reveals Chemotaxis-Mediated Intraorgan Crosstalk During CardiogenesisTranscriptomic Profiling of the Developing Cardiac Conduction System at Single-Cell ResolutionScRNA-Seq of the Cardiac Conduction System (p 379)Download figureDownload PowerPointSingle-cell RNA sequencing reveals novel markers of the cardiac conduction system, report Goodyer et al.The cardiac conduction system (CCS)—consisting of the sinoatrial node, atrioventricular node, bundle of His, bundle branches, and Purkinjie fibers—controls the rhythmic beating of the heart. As such, any disturbance to the CCS can cause arrhythmia or even sudden death. The small numbers of specialized cells comprising the CCS and the limited markers available for their identification, however, makes studying the CCS complicated. To address this and gain insight into CCS biology, Goodyer and colleagues harvested cells from CCS components of embryonic mouse hearts and performed single-cell RNA sequencing. Analysis of the data from 22 000 individually bar-coded cells revealed known cell types—based on established markers—and identified numerous new CCS-enriched genes. It also enabled identification of elusive CCS transitional cells, which connect the CCS to the surrounding myocardium and are implicated in several types of arrhythmia. Fluorescence in situ hybridization and immunolabelling of 3D-preserved, optically cleared heart tissue was used to validate several of the novel markers. Together, this sequencing and spatial data provide a gene expression atlas of the mouse CCS that will guide future studies into this essential electrical system, say the team.Chemotaxis-Mediated Second Heart Field Deployment (p 398)Download figureDownload PowerPointXiong et al, examine heart field progenitors at the single-cell RNA level.The developing mammalian heart originates from 2 areas of the early embryo called the first and second heart fields (FHF, SHF). Progenitor cells from these regions give rise to, largely speaking, different structures, with FHF cells ultimately forming the atria and left ventricle and SHF cells forming the right ventricle and outflow tract. A full understanding of how the FHF and SHF are regulated and interact, however, is lacking. To learn more, Xiong and colleagues isolated and performed RNA sequencing on ≈600 cells from each field (identified by marker expression) collected at 4 developmental time points. Sequence analysis revealed that FHF cells differentiated into cardiomyocytes in a gradual “wave-like” manner, say the authors, while SHF cells differentiated in a more step-wise fashion. The team also found high expression of migration factor MIF in FHF cells and MIF’s receptor, CXCR2, in SHF progenitors, suggesting FHF cells regulate SHF cell migration. Sure enough, blocking MIF-CXCR2 in cultured mouse embryos prevented SHF cell migration and normal development of right ventricular and outflow tract structures. Together, the results provide insights into both normal heart development and what may go awry in certain congenital heart malformations.Pulmonary Hypertension and Metabolic Syndrome (p 449)Download figureDownload PowerPointBy raising IL-6 levels, metabolic syndrome can worsen pulmonary hypertension, say Ranchoux et al.Pulmonary hypertension (PH) can arise from a number of causes, but chief among them is left heart disease (LHD), which itself can be the result of conditions such as diastolic dysfunction, aortic stenosis, or mitral valve disease. More than half of all patients whose PH is caused by LHD (known as group 2 PH) also have metabolic syndrome—a condition characterized by obesity with associated pathologies such as dislipidemia, type 2 diabetes, and high blood pressure. Metabolic syndrome can also be marked by elevated levels of the inflammatory cytokine IL-6, which in rats induces proliferation of pulmonary artery smooth muscle cells (PASMCs) and, consequently, PH. Ranchoux and colleagues now pull these pieces of the puzzle together showing that inducing metabolic syndrome in rats results in raised IL-6 and greatly exacerbated PH. Furthermore, they found that inhibition of IL-6 using either IL-6 antibodies or metaformin—a diabetes drug that the team showed can reduce IL-6 secretion from macrophages—could ameliorate such PH. IL-6 was also found to be raised in the lungs of PH patients and could induce proliferation of human PASMCs, suggesting not only that the observations in rats hold true for humans, but that metaformin could be studied as a potential treatment for group 2 PH treatment. Previous Back to top Next FiguresReferencesRelatedDetailsRelated articlesMetabolic Syndrome Exacerbates Pulmonary Hypertension due to Left Heart DiseaseBenoît Ranchoux, et al. Circulation Research. 2019;125:449-466Single-Cell Transcriptomics Reveals Chemotaxis-Mediated Intraorgan Crosstalk During CardiogenesisHaiqing Xiong, et al. Circulation Research. 2019;125:398-410Transcriptomic Profiling of the Developing Cardiac Conduction System at Single-Cell ResolutionWilliam R. Goodyer, et al. Circulation Research. 2019;125:379-397 August 2, 2019Vol 125, Issue 4 Advertisement Article InformationMetrics © 2019 American Heart Association, Inc.https://doi.org/10.1161/RES.0000000000000290 Originally publishedAugust 1, 2019 PDF download Advertisement

Permanent HIS bundle Pacing Feasibility in Routine Clinical Practice: Experience from an Indian Center

There is a paucity of experience regarding His bundle pacing (HBP) at laboratories initially attempting the procedure, especially in the Indian scenario. Patient who underwent HBP were selected for pacing therapy or in lieu of cardiac resynchronization therapy (CRT) at a single center. Among 22 patients attempted, 19 patients underwent successful implant, achieving selective HBP in 14 patients. There was a significant improvement in left ventricular ejection fraction (LVEF) (49.3 ± 9.3 vs. 36.7 ± 9.2) in the LV dysfunction subgroup (n = 6). Over a follow-up of 15 ± 6.5 months, thresholds were stable in all except one patient, and there was no requirement of lead revision. In summary, we found that HBP is a feasible option for achieving physiological pacing.

His bundle has a shorter chronaxie than does the adjacent ventricular myocardium: Implications for pacemaker programming

Strength-duration curves for permanent His bundle (HB) pacing are potentially important for pacemaker programming. We aimed to calculate strength-duration curves and chronaxies of the HB and of the adjacent right ventricular (RV) working myocardium and to analyze zones of selective HB capture and battery current drain when pacing at different pulse durations (PDs). Consecutive patients with permanent HB pacing were studied. The RV and HB capture thresholds were assessed at several PDs. Battery current drain and zones of selective HB capture at PDs of 0.1, 0.2, 0.4, and 1.0 ms were determined. In the whole group (N = 127), the HB chronaxie was shorter than the RV chronaxie. This difference was driven by patients with selective HB pacing (HB chronaxie 0.47 ms vs RV chronaxie 0.79 ms). The strength-duration curve for the HB had a lower rheobase and its steep portion started at shorter PDs, thus creating wider distance-zone of programmable selective HB pacing-between the HB and RV strength-duration curves at shorter PDs. The battery current drain was lower with pacing at PDs of 0.1-0.4 ms vs 1.0 ms. Chronaxie-adjusted PDs offered the lowest current drain. For the first time, the strength-duration curves for permanent selective and nonselective HB pacing were determined. Selective HB capture and battery longevity can be promoted by shorter PDs (0.2 ms). Longer PDs (1.0 ms) offer greater safety margin for RV capture and may be preferable if simultaneous RV capture during HB pacing is desired.

Comparison of area under curves for serum methylglyoxal and glucose in patients with diabetes mellitus

The lower limit of the membranous septum (MS) is considered an anatomic landmark for the emergence of the Bundle of His into the left ventricle. Computed tomography (CT) assessment of MS anatomy may provide useful information about the risk of conduction abnormalities following transcatheter aortic valve replacement (TAVR).The study included 102 consecutive patients undergoing TAVR with the Edwards Sapien 3 (S3) valve. Using pre-TAVR CT and post-procedure angiography we evaluated for the presence of calcium in the left ventricular outflow tract (LVOT), calcium depth (CD), implantation depth (ID) and MS length. The MS length minus the prosthesis ID was calculated (Delta MSID). Outcomes included new left bundle branch block (LBBB) or permanent pacemaker (PPM) within 30 days. Seventeen patients (17%) received a PPM and 28 (27%) developed new LBBB following TAVR. Mean (± SD) MS length and delta MSID were 7.5 mm (2) and 0.9 mm (4.5), respectively. Twenty-one patients (20%) had calcium in the device landing zone and the mean (SD) CD was 6.8 mm (± 4). Calcium in the device landing zone (37% versus 16%, p = 0.02) and implantation depth (6 mm (4–8) versus 4 mm (4–5), p = 0.02) predicted new conduction abnormalities after TAVR.The presence of calcium in the device landing zone is associated with increased risk of conduction abnormalities after TAVR with S3. In such cases, a more aortic deployment of the prosthesis may be warranted.

Effect of selective His bundle pacing on ventricular fibrillation activation rates in rabbit hearts

Background/significanceThe His‐Purkinje system is electrically active and influences activation patterns and rates during ventricular fibrillation (VF). Purkinje system is involved in maintaining VF and may contribute to defibrillation shock failure. This study investigates if the His‐Purkinje system could be paced to modulate rate or patterns of activation during VF.MethodSeven New Zealand rabbit hearts were explanted and perfused in a Langendorff setup. The His bundle (HB) was accessed from the right atrial septal wall by opening the right atrium. An 8×8 Ag/AgCL electrode array was placed by the anterior vertex of Koch's triangle. The HB was identified using a custom real‐time stimulation‐recording and signal processing system. The system used spatial derivatives to identify electrodes specifically over the HB. A separate silver wire was inserted in the ventricular myocardium (VM) of the right septal wall to stimulate the VM and detect ventricular cycle lengths. A 64‐channel basket catheter (Orion catheter, Boston Scientific Inc) was inserted through an opening made in left atrium through the mitral valve and into the left ventricle. VF was induced by 50 Hz pacing on the left ventricular free wall. During VF, the HB was paced at 80 and 95% of intrinsic HB cycle lengths. Both the HB and VM were paced at 80 and 95% of the intrinsic VM cycle lengths. Both HB and VM were stimulated during VF at 10× the amplitude of the diastolic stimulation threshold. While the VM and HB were being stimulated, left ventricular endocardial activations were recorded from the basket catheter electrodes.The left ventricular endocardial recordings were analyzed using a custom graphical user interface developed in MATLAB (Mathworks, Inc., MA, USA). Broken channels or channels not in contact with the endocardial wall were excluded from the analysis.ResultsData from 2 out of 7 animals were excluded from analysis as pacing at electrodes with HB potentials did not lead to capture of the HB. HB pacing at 80% or 95% of HB CL did not affect the VF. In 4 animals, when the HB was paced at 95% of VM cycle lengths, the left ventricular endocardial activation rate was higher than when VM was paced at 95% of VM cycle lengths. In 3 animals, when HB was paced at 80% of VM cycle length, the left ventricular endocardial activation rate was higher than when the VM was paced at 80% of VM cycle length.Conclusion and discussionHB paced at 80 or 95% of HB cycle length did not affect the underlying VF. HB paced at 80% or 95% of VM cycle length affected the underlying VF activation rate more than when VM was paced at 80% or 95% VM CL. The increase in ventricular activation rate suggests ventricular tissue is activated at the Purkinje endpoints of the His‐Purkinje system as a result of His bundle pacing.Support or Funding InformationNational Institutes of Health award number R01HL128752 to Dr. Derek DosdallThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

HIS BUNDLE PACING TO TREAT TRICUSPID REGURGITATION CREATED BY RIGHT VENTRICULAR LEAD PLACEMENT

His Bundle pacing has reemerged as an alternative to ventricular pacing in hopes to resynchronize the ventricles, narrow the QRS complex and improve clinical symptoms of congestive heart failure. Multiple case reports have documented the benefit of HIS bundle pacing; however, severe tricuspid

SYNCOPE AND AN INTRA-HISIAN ATRIOVENTRICULAR (AV) BLOCK AFTER RADIATION THERAPY

Disease in Bundle of His (Intra-His block) presents an uncommon diagnostic challenge to clinicians. Formal diagnosis is made with electrophysiological (EP) study. We present a patient with remote history of chest radiation (XRT) for breast carcinoma and sudden onset syncope. 53-year old female

HIS BUNDLE PACING INSIGHTS FROM ELECTRO-ANATOMICAL MAPPING: TOPOGRAPHY AND PACING TARGETS

Visualization of selective (S) and non-selective (NS) His bundle (HB) capture areas by 3D electro-anatomical mapping (EAM) has not been described and may help to guide HB pacing (HBP). The objective was to conduct EAM of the AV septum by using pace- and activation mapping. EAM was performed with

Direct Visualization of the His Bundle Pacing Lead Placement by 3-Dimensional Electroanatomic Mapping: Technique, Anatomy, and Practical Considerations.

His bundle pacing (HBP) remains technically challenging and is currently guided by electrograms and 2-dimensional fluoroscopy. Our objective was to describe a new technique for HBP directly guided by electroanatomic mapping (EAM). Twenty-eight patients were included. The atrioventricular septum was mapped via EAM, and His bundle (HB) electrograms, selective, and nonselective HB capture sites were tagged. Pacing leads were connected to EAM, navigated to tagged HB target sites and deployed. Intracardiac electrograms and pacing parameters were recorded. Lead location was tagged on the cloud of HB sites, which was divided into 3 arbitrary segments. In 5 patients, atrioventricular nodal ablation was performed with direct visualization of the HBP lead by EAM. Reproducible navigation of the pacing lead to predetermined HBP locations guided by EAM was achieved in all patients. The lead was successfully deployed in 25 patients. HB cloud area was 360 (212) mm2. There was no correlation between HBP threshold and lead location on the His cloud. The intracardiac electrograms atrial/ventricular ratio at the lead deployment site correlated with its EAM position on the His cloud ( P=0.045). Procedure, fluoroscopy, and mapping times were 116.0 (38.8), 8.6 (6.3), and 9.0 (11.4) minutes, respectively. HBP threshold at implant was 1.5 (2.3) V at 1.5 (1.0) ms. Distance between HB lead and ablation sites was 10.0 (1.3) mm in patients undergoing atrioventricular nodal ablation. Direct guidance of HBP by EAM allows for direct visualization of the pacing lead on the HB cloud and reproducible navigation to predetermined HB capture sites. Intracardiac electrograms atrial/ventricular ratio at the lead deployment site correlates with His cloud location. EAM can be applied during standard HBP procedures or combined with atrioventricular nodal ablation.

Cryoablation of the para-Hisian region

Basis: the ablation of the para-Hisian region is a challenge due to the risk of inadvertent lesion of a bundle of His. Cryoablation, due to its slower progression, allows interruption of the application in case of signs of undesired lesions and catheter adhesion during the applications, which has made cryoablation the ideal method for these patients. Objectives: to demonstrate the results of an initial series of patients referred for cryoablation of para-Hisian pathways. Patients and methods: From April 2015 to August 2017, 13 patients were referred for cryoablation due to the necessity for a para-Hisian approach detected in previous ablation procedures. Of the 13 patients, seven were submitted a radiofrequency ablation attempt (RF) and presented failure or recurrence, five performed only electrophysiological studies, and no ablation was attempted, and one was indicated primarily. The mean age was 32 ± 16 years. Eleven patients had manifest anomalous pathways (APs), one hidden and one nodal reentrant tachycardia (NRT) with a transient atrioventricular block (AB) during RF. A cycle of 4 minutes followed by one more cycle in case of a positive result. Results: Of the 13 patients, 11 had an acute success in eliminating the accessory pathway. One patient had multiple accessory pathways, one right side, and one left side. In this patient, it was possible only the ablation of the left pathway. In all others, it was observed exuberant Hisian potential at the point of application with success. The patient with NRT was ablated in the M region without intercurrences. Four applications were required on average to eliminate the accessory pathway successfully. The mean local temperature was -74 ºC. In five patients, the occurrence of third-degree right branch block (RBB) was observed. In one patient, early application of RBB was interrupted and the bonus application was not applied. This wasthe only acutely successful patient who presented clinical recurrence. Transient AB was not observed in any patient. No complications were observed. Conclusion: Cryoablation of para-Hisian pathways and NRTs in regions surrounding the His was an effective method for treatment in this population of patients refractory or refused for RF treatment. The occurrence of acute RBB does not seem to be a criterion for the interruption of applications.

Mitral Annulus Calcium Score

Background: The risk of conduction system abnormalities (CSA) after transcatheter aortic valve implantation remains high. We aimed to evaluate the impact of mitral annular calcium (MAC) score on th...

Learning Curve and Initial Experience of Implementing a HIS Bundle Pacing Program

Learning Curve and Initial Experience of Implementing a HIS Bundle Pacing Program

Indication of permanent cardiac pacing after transcatheter aortic valve implantation (TAVISTIM NCT02337140)

Regarding the extent of TAVI's indication to patients with intermediary risks, it seems essential to lower its complication. Conduction disturbances after TAVI remains a major complication without any standardized guidelines to help with its treatment. The primary end-point of this study is to confirm that standard criterion for pacing are reliable in post-TAVI conduction disorders and to analyze the contribution of a systematic electrophysiological study. In TAVI patients, indications for pacing were persistent high-degree atrioventricular block or bundle branch block appearance associated to HV interval longer than 70 ms, 24 hours after the procedure. After a two-month follow-up, clinical and ECG evaluation and 24-hour ECG Holter monitoring were realized in patients without pacemaker and compared to data obtained from the devices in pacemaker implanted patients (% of ventricular pacing > 1%; presence of more than 1 AVB episode). A total of 165 consecutive patients who underwent TAVI were prospectively included. Out of the 165 patients included, 157 were sampled: 20 in the high grade persistent AV block, 5 in the persistent bundle branch heart block with HV interval > 70 ms, 13 with HV interval < 70 ms, and 119 in the temporary conduction disturbances group. Amongst the 22 patients implanted with PMK following the protocol, only 1 had conduction recovery. On the other hand there were 14 patients who didn’t benefit from a PMK implant but should have. HV interval in the bundle branch block group has an 88% specificity and a 44% sensibility. None of the pacing indication would have been missed if considered at day 3 instead of day 2, independently of HV measurement. From this experimental protocol it appears that an HV based algorithm has a good specificity but a poor sensibility. Conduction disorders are stable at day 3 and allow to decide if pacing is needed. Besides QRS duration, PR interval might be of interest in predicting risk of AV block after TAVI.