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Objective To investigate the electrophysiological characteristics and curative effect of radiofrequency ablation(RFA)of idiopathic ventricular arrhythmias(VAs)originating from the right bundle branch of the moderator band.Methods The patients(n=10)with idiopathic VAs originating from the right bundle branch of the moderator band verified by electrophysiological examination and RFA were chosen from Department of Cardiology in Beijing Anzhen Hospital affiliated to Capital Medical University from April 2019 to July 2022.Excited sequence mapping and pacing mapping were performed respectively on the moderator band.The characteristics of surface ECG,electrophysiological characteristics and potential characteristics at successful ablation targets were analyzed,and curative effect of RFA was observed and analyzed.Results Idiopathic VAs originated from the moderator band,and surface ECG showed mostly graph of left bundle branch block(LBBB)with left superior axis deviation and a narrower QRS complex.All patients showed an rS wave in leads V,and V2,and no notching on the S wave downstroke.The R-wave transition lead was at leads V4-V6 during VAs,which was later than that during sinus rhythm in all patients.All patients had an R wave in lead V6.A leading RBB potential at the target during VAs was observed for all patients.Ablation of the leading RBB potential effectively eliminated the arrhythmia.6 patients showed RBB block after ablation and 2 of them were recovered during follow-up.Conclusions Electrocardiographic of MB-RBB VAs is characterized by a typical left bundle branch block pattern with a relatively narrow QRS complex,and left superior axis deviation.The R-wave transition lead was later than that during sinus rhythm.Ablation of the leading RBB potential are effective in eliminating VAs.
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Background and objectives: Moderator band is a specialized bridge present between the base of the anteriorpapillary muscle and interventricular septum. It carries the right branch of the bundle of HIS with it. The band isknown to prevent the over distension of the right ventricle during the diastolic phase. There is a need of lot ofresearch and studies on the septomarginal trabecula as it proves to be important clinically. Here we measuredthe length, breadth, height, angle with the interventricular septum, and the superficial marking of Moderatorband on the sternocostal surface of the right ventricle is done. This paper describes the morphological variationsfound in its origin and insertion.Materials and Methods: 15 formalin-soaked cadaveric hearts were taken from the Department of Anatomy ofKVG Medical College, Sullia. The foetal hearts, the hearts with gross pathology, if any are excluded from the study.Result: The morphometric parameters are tabulated and the morphological variations are noted. The results arecompared with the results of the previous studies on the moderator band.Conclusion: It is confirmed that the thickness of moderator band varies at its origin and insertion. The surfacemarking of moderator band on sternocostal surface of the heart will help in locating the moderator band throughthe echocardiography and during cardiac surgeries on right ventricle. The possibility of second moderator band,multiple origin or insertion is more than 20%.
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Background: The moderator band has the right bundle of His within the right ventricle. It also is known to prevent the over dilatation of RV. It is important because of its involvement in RV infarcts, in differentiating RV from LV in congenital anomalies, in VPDs & VTs and in VSDs. The present literature is very much lacking in its morphometry. Materials and Methods: Moderator band was looked for in 50 hearts and only in this study did we find it in all the hearts. The length, the thickness, the distance from the tricuspid valve along with the presence of any trabeculations in the septal end or in the papillary muscle end were looked for and recorded. Results: The average length was 14.71±4.99mm, the average thickness was 4.97±1.64 mm, the average distance from the tricuspid orifice was 19.85±5.92 mm. The attachment to the anterior papillary muscle was found to be branched in 8 hearts that is having an incidence of 14% . The septal end were branched and separated as two in only two specimens. Only one specimen had branched attachments on both the apical and septal ends. Conclusion: The distance from tricuspid valve and knowledge of branching are important in corrective surgeries of the VSDs. An awareness of length and thickness helps the clinician to differentiate moderator band from the other structures, which may result in misdiagnosis during echocardiography. Its presence may in fact be of significance in preventing over distension of the heart in RV myocardial ischaemia.
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We report herein a case of 35-year-old male with a history of complex congenital heart disease, consisting of double-chambered right ventricle (DCRV) with ventricular septal defect and presenting with transient 2:1 atrioventricular (AV) block on electrocardiogram. This unique presentation has not yet been described in literature, hence it was worth describing this rare complication of DCRV.
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The specimens were taken from two adults' hearts, thirty-four and twenty-eight years of age respectively. The A-V bundle was taken from the middle part of postero-inferior edge of the membranous part of the ventricular septum. The moderator band were cut from its superficial and deep part. The pseudochordae tendineae were collected from the left ventricle. All of the samples were fixed by 4％ glutaraldehyde. The chief results were as follows:There are many Purkinje cells in the A-V bundle, moderator band and pseudochordae tendineae. The shape of the Purkinje cells is broader and shorter than the ordinary myocardial cells. The myofibrils and myofiliments of the Purkinje cells are less than of those of the ordinary myocardial cells. The mitochondria of the Purkinje cells were often situated around the nucleus. In the A-V bundle, a few transitional cells and general myocardial cells may be observed. Therefore the His bundle may be consisted of Purkinje cells transitional cells and a few general myocardial cells. Our findings are not in accordance with that of Glomset et al. They observed that the A-V bundle only consisted of the general ventricle myocardial cells. The intercalated discs present between the Purkinje ceils in the A-V bundle were not typical. Besides the intercalated discs, we observed two sorts of the junction types in the A-V bundle: (1) An intercalated disc was observed between a branch of a transitional cell and the lateral surface of the other adjacent transitional cell. (2) Through the collagenous septum, there was a junction between a transverse branch of transitional cell and opposite transitional cell.