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At least 55 records · Page 3Linked to original sources
PubMed1977

Pseudo bundle branch block produced by premature impulses arising in the bundle branches.

Pseudo bundle branch block, a previously unreported arrhythmia produced by concealed premature impulses arising in the bundle branches, was seen in two patients with sick sinus node syndrome. Although concealed conduction was not apparent in either the surface or intracardiac leads, the latter were essential in localizing the site of manifest impulse formation. Patient 1, with left bundle branch extrasystoles, had pseudo bundle branch block and pseudo atrioventricular block that depended on the timing and extent of concealment of premature depolarization. Because of the coexisting sinus bradycardia in this patient, electrical stimulation and the recording of the right ventricular apical electrograms gave additional information that helped corroborate the postulated mechanisms. Patient 2 had right bundle branch extrasystoles with sinus beats that showed a right bundle branch block pattern possibly caused by pseudo bundle branch block. In this case the possibility that both the automaticity and the conduction disturbance had a mechanical origin could not be excluded.

Arrhythmia, Sinus↗
PubMed1986

Bundle branch reentrant tachycardia treated by electrical ablation of the right bundle branch.

A 66 year old man presented with multiple episodes of tachycardia. Some had QRS complexes with a right bundle branch block configuration identical to those of sinus beats. The onset of the tachycardia was preceded by premature His bundle depolarizations. There was a His potential before each QRS complex of the tachycardia. Atrial activity was dissociated. Occasionally the appearance of sinus beats with a left bundle branch block pattern announced a tachycardia with an identical configuration and atrioventricular dissociation. His bundle activity occurred before the QRS complex and was followed by a right bundle branch deflection. A reentrant mechanism within the bundle branch system was invoked. One 200 J shock was delivered through an electrode catheter to the site of the right bundle branch. The postprocedure course was uneventful (follow-up 10 months).

Aged↗
PubMed1980

Wolff-Parkinson-White syndrome type B with tachycardia-dependent (phase 3) block in the accessory pathway and in left bundle-branch coexisting with rate-unrelated right bundle-branch block.

A patient with Wolff-Parkinson-White syndrome type B developed 2:1 atrioventricular block resulting from the association of persistent right bundle-branch block with tachycardia-dependent (phase 3) left bundle-branch block. Electrophysiological studies disclosed the coexistence of a tachycardia-dependent (phase 3) block in the accessory pathway. This conduction disturbance was exposed, not by carotid sinus massage as in previous studies, but by pacing-induced prolongation of the interval between two consecutively conducted atrial impulses. Furthermore, the surface electrocardiogram showed, at different times, ventricular complexes resulting from: (1) exclusive atrioventricular conduction through the normal pathway without bundle-branch block; (2) predominant, or exclusive, atrioventricular conduction through a right-sided accessory pathway; (3) exclusive atrioventricular conduction through the normal pathway with right bundle-branch block; (4) exclusive conduction through the normal pathway, with left bundle-branch block; (5) fusion between (1) and (2); and finally, (6) fusion between (2) and (3) However, QRS complexes resulting from simultaneously occurring Wolff-Parkinson-White syndrome type B and left bundle-branch block could not be identified. Future electrophysiological investigations should re-evaluate the criteria used to diffrentiate between true and false patterns of Wolff-Parkinson-White syndrome type B coexisting with left bundle-branch block.

Bundle-Branch Block↗
PubMed1999

The 135-kDa actin-bundling protein from lily pollen tubes arranges F-actin into bundles with uniform polarity.

A plant 135-kDa actin-bundling protein (P-135-ABP) isolated from pollen tubes of Lilium longiflorum (Thunb.) binds stoichiometrically to F-actin filaments and bundles them in vitro (E. Yokota et al., 1998, Plant Physiol. 116: 1421-1429). To further understand the mechanism of actin-filament bundle formation by P-135-ABP, the polarity of each F-actin filament in bundles was examined using myosin subfragment 1 (S-1). Dissociation of F-actin filaments from bundles organized by P-135-ABP was induced by S-1. However, F-actin filaments that remained in a bundle and decorated by S-1 showed uniform polarity. These results indicate that P-135-ABP arranges F-actin filaments into bundles with uniform polarity and consequently plays a key role in the orientation of cytoplasmic streaming in pollen tubes.

Journal Article↗
PubMed2004

Computational models of hair cell bundle mechanics: II. Simplified bundle models.

Simplified versions of hair cell bundles are mechanically modeled. The influence of various geometric and material combinations on bundle stiffness, link tensions and deformation shape are examined. Three models are analyzed within this paper: two stereocilia connected by one link, two stereocilia connected by a biologically realistic set of links, and a column of stereocilia connected by realistic links. Stereocilia are modeled using a distributed parameter model [J. Biomech. Eng. 122, 44]. Some fundamental rules for linking bundles emerge from these tests: (1) Links must have a threshold stiffness value for the bundle to deform as a whole. Beyond this value, the stereocilia are perfectly linked and variations in link stiffness do not significantly effect the bundle stiffness or link tension. (2) Decreasing the relative heights of successive stereocilia may increase link tension while decreasing bundle stiffness. (3) When lateral links exist, the top most lateral links carry the majority of tension. Lower links in single column model appear mechanically insignificant. (4) Extending the length of the bundle in a column does not increase the stiffness once the column reaches a certain length.

Animals↗
PubMed2000

The effect of hair bundle shape on hair bundle hydrodynamics of inner ear hair cells at low and high frequencies.

The relationship between size and shape of the hair bundle of a hair cell in the inner ear and its sensitivity at asymptotically high and low frequencies was determined, thereby extending the results of an analysis of hair bundle hydrodynamics in two dimensions (Freeman and Weiss, 1990. Hydrodynamic analysis of a two-dimensional model for micromechanical resonance of free-standing hair bundles. Hear. Res. 48, 37-68) to three dimensions. A hemispheroid was used to represent the hair bundle. The hemispheroid had a number of advantages: it could represent shapes that range from thin, pencil-like shapes, to wide, flat, disk-like shapes. Also analytic methods could be used in the high frequency range to obtain an exact solution to the equations of motion. In the low frequency range, where an approximate solution was found using boundary element methods, the sensitivity of the responses of hair cells was mainly proportional to the cube of the heights of their hair bundles, and at high frequencies, the sensitivity of the hair cells was mainly proportional to the inverse of their heights. An excellent match was obtained between measurements of sensitivity curves in the basillar papilla of the alligator and bobtail lizards and the model's predictions. These results also suggest why hair bundles of hair cells in vestibular organs which are sensitive to low frequencies have ranges of heights that are an order of magnitude larger than the range of heights of hair bundles of hair cells found in auditory organs.

Acoustic Stimulation↗
PubMed1976

Anatomical configuration of the His bundle and bundle branches in the human heart.

The relationships among the His bundle, the origin of both bundle branches, and the interventricular (IV) septum were examined histologically in 32 human hearts, and the entire bundle branch systems were delineated in 13 of these. The His bundle in five hearts traversed the right IV septal crest, and the LBB origin was a very narrow stem (maximum 1.5 mm in cross-section) crossing from right to left through the inferior margin of the membranous septum. Proximal LBB anatomy was extremely variable, demonstrating multiple fiber groups which fanned out over the entire left septal surface. The LBB did not divide into two discrete divisions without multiple interconnections. The RBB formed an obtuse angle with the His bundle in 27 of 32 hearts. In those five hearts with "right-sided His bundles," the right bundle branch was a direct continuation. The clinical, electrophysiologic, and electrocardiographic implications of these anatomical observations are discussed.

Adolescent↗
PubMed1977

Transient unifascicular, bifasicular and trifascicular block: electrophysiologic correlations in a patient with rate-dependent left bundle branch block and transient right bundle branch block.

Correlations of the His to ventricular (H-V) conduction time were made with the surface electrocardiogram during normal intraventricular conduction, unifascicular block (right bundle branch block), bifascicular block (left bundle branch block) and trifascicular block (right and left bundle branch block) in a patient with rate-dependent left bundle branch block who had transient right bundle branch block during recording of the His bundle electrogram. The results provide a functional confirmation of the theory that a prolonged H-V time is a manifestation of trifascicular disease.

Bundle of His↗
PubMed1995

Long-term clinical outcome of right bundle branch radiofrequency catheter ablation for treatment of bundle branch reentrant ventricular tachycardia.

The study assessed the long-term outcome of patients undergoing radiofrequency ablation of the right bundle for bundle branch reentrant ventricular tachycardia. Bundle branch reentrant tachycardia was diagnosed in 16 patients (ejection fraction 31% +/- 15%) who underwent electrophysiology study in our laboratory. All patients had His-Purkinje system conduction delay with mean HV interval of 68 +/- 8 ms. After ablation, right bundle branch block developed in 15 patients. One patient developed complete heart block, which was anticipated. One patient died of heart failure 9 months after ablation. Two patients were successfully bridged to heart transplantation 0.5 and 13 months, respectively, after ablation. Two patients received implantable defibrillators for other ventricular tachycardias. One patient had syncope 11 months after ablation, but there was no evidence of ventricular tachycardia or heart block in repeat electrophysiology study. This patient died suddenly 29 months after ablation. The remaining nine patients were alive and well for a mean follow-up of 19 +/- 10 months. Radiofrequency ablation of the right bundle branch is an effective therapy for treatment of bundle branch reentrant ventricular tachycardia. Survival is excellent provided that other types of ventricular tachycardia, when present, are treated as well. This technique may be helpful in management of patients who have unacceptable frequent shocks from their implanted defibrillators and may be helpful in avoiding implantation of such a device completely in others. In some patients with terminal heart failure and incessant ventricular tachycardia, this procedure can function as a bridge to cardiac transplantation.

Adult↗
PubMed1979

Morphology of the atrioventricular node, bundle and proximal bundle branches: a study employing computerized reconstruction.

The morphology of the human atrioventricular node, atrioventricular bundle and bundle branches is described. A block of tissue bounded by the ostium of the coronary sinus, the pars membranacea, the septal leaflet of the tricuspid valve and the atrial and ventricular septa is removed. The block is then sectioned serially from the right endocardial surface in the frontal plane of the heart. Sectioning in this way produces fewer sections than from techniques previously described. Outlines of the atrioventricular node, atrioventricular bundle and proximal bundle branches are digitally registered and stored in a computer. Three dimensional reconstructions of the structures are then generated by computer and displayed on an oscilloscope so that the entire three dimensional image can be rotated in any plane. Stereoscopic image pairs are produced to assist perception of the shape of the atrioventricular node, bundle and branching patterns of the bundles. This technique is unique in that it describes a method from which a relatively small number of histologic sections are generated permitting not only a complete histologic examination, but also a study of the morphology of the area.

Adult↗
PubMed1987

Gap in bundle-branch conduction elicited by programmed His bundle stimulation.

The gap phenomenon in right bundle-branch conduction was elicited during programmed stimulation of the His bundle. Premature beats with short and long coupling intervals showed undisturbed intraventricular conduction, while the premature beat with intermediate coupling interval blocked within the right bundle branch. The electrophysiologic mechanism of "supernormal" conduction of the earliest beats was conduction delay at a proximal site within the His bundle which allowed recovery of the right bundle branch. This study shows that programmed His bundle stimulation is a valuable method in analyzing conduction characteristics of the distal atrioventricular conduction system in cases where atrioventricular nodal refractoriness would preclude this by atrial stimulation.

Adult↗
PubMed1994

Pleomorphic ventricular tachycardia with antegrade His-bundle activation: elucidation by multiple His-bundle recordings.

The use of multiple His bundle-right bundle branch recordings in electrophysiologic studies has facilitated definition of the mechanism and elucidation of the direction of impulse propagation in bundle branch reentrant tachycardia, "Mahaim" fiber reciprocating tachycardia, and retrograde His depolarization in fascicular or ventricular tachycardias. This report details the electrophysiologic evaluation of pleomorphic ventricular tachycardia in a patient with advanced coronary heart disease. The ventricular tachycardia at baseline revealed variation in the QRS duration without alteration of the electrocardiographic (ECG) morphology. Following flecainide administration, a ventricular tachycardia with close resemblance of the ECG morphology to sinus rhythm was induced. Proximal and distal His-bundle recordings revealed early antegrade His-bundle activation during this tachycardia. Programmed stimulation converted this tachycardia back to the clinical ventricular tachycardia with intermittent narrowing of the QRS complexes. Early His activation was evident only during the narrower complexes but not in the tachycardia beats with wide complex. Penetration of the His bundle by ventricular tachycardia, with resultant fusion from intramyocardial ventricular activation and His-Purkinje activation, could have accounted for the near normalization of the QRS morphology during the ventricular tachycardia.

Anti-Arrhythmia Agents↗
PubMed1981

["Slowing" right bundle-branch block in reciprocating tachycardia from a latent right lateral Kent bundle].

The authors report the case of a 56 year old man with paroxysmal reciprocating tachycardia. The participation of a right lateral Kent bundle, latent in sinus rhythm and with retrograde atrioventricular conduction during tachycardia was proved by : 1) the slowing of the tachycardia rhythm and lengthening of the ventriculo-atrial conduction time by 50 ms during right bundle branch block ; 2) atrial mapping during tachycardia showing right lateral atrial pre excitation ; 3) the spontaneous termination of some attacks after a blocked Hisian depolarisation. Analysis of the mechanisms of spontaneous termination of tachycardia showed a block in the accessory pathway in 80% of cases, leading to the successful use of Amiodarone. The particular electrophysiological mechanism of functional bundle branch block makes it the most reliable positive diagnostic criterion in reciprocating tachycardia. A review of previously reported series shows participation of right lateral and septal accessory pathways to be uncommon during reciprocating tachycardia. Functional bundle branch block does not necessarily lengthen the ventriculo-atrial interval with septal accessory pathways. Left lateral Kent bundles are much more common. These points are analysed together with the mechanism of functional bundle branch block in the discussion.

Bundle-Branch Block↗
PubMed1979

His bundle block and concealed His bundle premature depolarization.

His bundle electrocardiograms were recorded from a patient with previously unexplained PR prolongations or shortenings suggestive of both type I and II second degree AV block. The conduction disturbances were due to the association of concealed His bundle depolarizations (H') not propagated to atria or ventricles with first degree AV block in the His bundle. These data strongly suggest that frequent spontaneous His bundle depolarizations are another manifestation of a disease process involving the His bundle, a kind of "Sick--His bundle syndrome".

Bundle of His↗
PubMed1983

Differentiation of the atrioventricular node, the atrioventricular bundle and the bundle branches in the bovine heart: an immunohistochemical and enzyme histochemical study.

The previous observations of differences between different cardiac regions (ventricular myocardium, atrial myocardium, Purkinje fibre system) with respect to the maturation of the M-line region and the establishment of mature metabolic characteristics, have been extended. It was found that M-line maturation proceeds differently also between different regions of the conduction system. The M-line proteins, myomesin and MM-creatine kinase, were detected earlier, by means of immunohistochemistry, in the AV bundle and bundle branch cells than in the AV node cells. Also, a difference was observed in large foetuses. Striations in the AV node were less evident than in the AV bundle and the bundle branches in sections incubated with antibodies against myomesin as well as against MM-creatine kinase. Using enzyme histochemistry it was observed that the differences in metabolic properties between the AV node, the AV bundle and the bundle branches on the one hand, and the ordinary myocardium on the other, of adult hearts, are not established at the early stages. No clear difference in activity of succinate dehydrogenase was seen between the conduction tissues and the ordinary myocardium in the foetal hearts, while the conduction tissues showed a lower activity in the adult hearts. Furthermore, the pattern of activity of mitochondrial glycerol-3-phosphate dehydrogenase between the conduction tissues and the atrial and ventricular myocardium was quite different in early foetal stages compared with the adult stage.

Animals↗
PubMed2006

Anterior cruciate ligament augmentation procedure with a 1-incision technique: anteromedial bundle or posterolateral bundle reconstruction.

Arthroscopic examination before anterior cruciate ligament (ACL) reconstruction sometimes reveals that there is a relatively thick ACL remnant bridging the femur and the tibia that may function to stabilize the knee, although its attachment is not the same as the anatomic site. We have established an ACL augmentation procedure that preserves the ACL remnant with the 1-incision technique using an autogenous semitendinosus tendon and EndoButton-CL (Acufex, Smith & Nephew, Mansfield, MA) instead of ACL reconstruction. When the ACL remnant was attached to the anteroinferior portion of the anatomic femoral origin and the posterolateral (PL) bundle was well preserved, the anteromedial (AM) bundle was reconstructed. When, in contrast, the ACL remnant was attached to the high-noon position with a well-preserved AM bundle, the PL bundle should be reconstructed. We have performed 13 AM bundle reconstructions and 4 PL bundle reconstructions. The merits of our ACL augmentation procedure are (1) it is performed under arthroscopy with 1 incision, (2) it avoids resection of the ACL remnant, which contributes to prevention of anterior laxity, (3) it preserves the ACL remnant's neural elements and mechanoreceptors, and (4) it provides a favorable influence on vascularity and reinnervation to the graft.

Anterior Cruciate Ligament↗
PubMed2004

The effect of hair bundle shape on hair bundle hydrodynamics of non-mammalian inner ear hair cells for the full frequency range.

The effect of the size and the shape of the hair bundle of a hair cell in the inner ear of non-mammals on its motion for the full range of frequencies is determined thereby extending the results of a previous analysis of hair bundle motion for high and low frequencies [Hear Res. 141 (2000) 39-50]. A hemispheroid is used to represent the hair bundle because it can represent a full range of shapes, from thin, pencil-like shapes to wide, flat, disk-like shapes. Boundary element methods are used to approximate the solution for the hydrodynamics. For physiologically relevant parameters, an excellent match is obtained between the model's predictions and measurements of hair bundle motion in the free-standing region of the basilar papilla of the alligator lizard [Aranyosi, Measuring sound-induced motions of the alligator lizard cochlea. Massachusetts Institute of Technology, PhD Thesis, 2002]. Neither in the model's predictions nor in experimental measurements is sharp tuning observed. The model predicted the low frequency region of neural tuning curves for the alligator lizard and bobtail lizard, but could not predict the sharp tuning or the high frequency region. An element that represents an active mechanism is added to the hair bundle model to predict neural tuning curves, which are sharply tuned, and an excellent match is obtained for all the characteristics of neural tuning curves for the alligator lizard, and for the low and high frequency regions for the bobtail lizard. The model does not predict well the sharp tuning of the shorter hair bundles of the bobtail lizard, possibly because it does not represent tectorial sallets.

Animals↗