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At least 19 recordsLinked to original sources
PubMed1976

Lidocaine and His bundle extrasystoles. His bundle discharge conducted with functional right of left bundle-branch block, or blocked entirely (concealed).

In this patient, discharge from the bundle of His either conducted normally, conducted with functional right or functional left bundle-branch block, or blocked entirely (concealed), depending on the preceding cycle length and the coupling interval of the premature His bundle depolarization. The presence of both functional right and left bundle-branch block may have been attributable to differences in effective and functional refractory periods between the two bundle branches. Concealed His bundle extrasystoles mimicked first-degree, and types I and II second-degree AV block, according to the interval between His bundle discharge and the subsequent P wave. Lidocaine eliminated His bundle extrasystoles that blocked entirely (concealed) or conducted with functional left bundle-branch block by improving His-Purkinje conduction and by lengthening the coupling interval of the premature His bundle extrasystole. Lidocaine had no effect on AV nodal conduction time. This patient has been known to have concealed His bundle discharge for at least three years and has not required permanent pacemaker insertion.

Bundle of His↗
PubMed1998

[Transformation of left bundle branch block into simulated bundle branch block after ablation of the right bundle in a patient with branch-to-branch reentry ventricular tachycardia].

Masquerading bundle branch block associates left bundle branch block in the standard lead and right bundle branch block in the precordial leads. Mr R., 67 year old, was referred for investigation of syncope. He had a history of idiopathic dilated cardiomyopathy (normal coronary arteries; EF: 14%, CI: 2.2 l/min/m2 at later investigations). The ECG showed LBBB with left axis deviation, a PR interval at the upper limits of normal and ventricular premature beats. During observation, he had another syncopal episode and the ECG showed wide complex tachycardia (160 bpm) reduced by external cardioversion. Electrophysiological investigations showed inducible VT due to bundle branch reentry. The HV interval in sinus rhythm was 80 ms. Radiofrequency ablation of the right bundle led to first degree AVB with masquerading bundle branch block with an increased HV interval of 120 ms. The usual facility of ablation of the right bundle branch block is an argument in favour of the hypothesis whereby masquerading bundle branch block is a variety of RBBB with severe conduction defects of the two branches.

Aged↗
PubMed1983

Determination of the left bundle branch refractoriness by distal His bundle pacing in patients with left bundle branch block.

Electrophysiological studies were carried out in two patients with an idiopathic left bundle branch block. Consistent distal His bundle pacing resulted in the normalization of the QRS complex in both patients. Extrastimulation during basic distal His pacing at several cycle lengths was carried out successfully. Using this technique, the refractory periods of the left bundle branches were measured and found to be within the normal range. In addition, they decreased with the shortening of the basic cycle length. These results demonstrated the possibility of determining the refractoriness of the left bundle branch by His bundle pacing in patients with left bundle branch block. Hypotheses are postulated about the presumed location of the lesion responsible for the left bundle branch block.

Adult↗
PubMed1978

Normalization of bundle branch block patterns by distal His bundle pacing. Clinical and experimental evidence of longitudinal dissociation in the pathologic his bundle.

Clinical and experimental observations in which bundle branch block patterns (BBBP) in ECG leads were normalized by distal His bundle (H) pacing are reported. The clinical material includes four patients with acute right BBBP secondary to anterior wall myocardial infarction and three patients with chronic left BBBP. Six of the seven patients had a prolonged H-V interval (60-85 msec) including three who showed evidence of an intra-H conduction delay (IHCD) with split H (H and H'). Distal H pacing from a right-sided electrode catheter normalized the BBBP with a stimulus-to-QRS (PI-V) interval 20-35 msec shorter than the H-V interval and almost identical to the H'-V interval in the three patients with documented IHCD. In 18 dogs ligation of the anterior septal artery resulted in IHCF with split H associated with right or left BBBP. Distal H pacing from catheter and/or plunge wire electrodes normalized the BBBP in 12 experiments (67%) with a PI-V interval identical to the H'-V interval. H pacing was selective and direct stimulation of myocardium was excluded by monitoring the high ventricular septal electrogram. The clinical and experimental observations are discussed as evidence that functional longitudinal dissociation is probably only operative in the pathologic H due to selectively greater depression of conduction in the transverse interconnections.

Animals↗
PubMed2004

Two-bundle posterior cruciate ligament reconstruction: how bundle tension depends on femoral placement.

BACKGROUND: Clinically, one-bundle posterior cruciate ligament reconstructions frequently result in the return of abnormal posterior translation. We hypothesized that the return of posterior translation is caused by a nonuniform distribution of load among the graft fibers. The purpose of the present study was to determine how the femoral attachment location of the second bundle of a two-bundle posterior cruciate ligament reconstruction affects the anterior bundle tension and the load distribution between the graft bundles. METHODS: One and two-bundle posterior cruciate ligament reconstructions (one one-bundle type and three two-bundle types) were performed in nineteen cadaveric knees. The grafts were tensioned to restore posterior translation to within +/-1 mm of that of the intact knee at 90 degrees of flexion while a 100-N posterior force was applied to the proximal part of the tibia. For each reconstruction, the total graft tension was a minimum of 2.3 times larger than the applied posterior force. Bundle tension and knee motions were measured as the knee was cycled from 5 degrees to 120 degrees of flexion while a 100-N posterior force was applied. Analysis of variance was used to compare the four reconstructions, and post hoc testing was performed with use of Fischer's protected least significant difference method. RESULTS: Two-bundle reconstructions involving a middle-distal or middle-middle second bundle significantly reduced the tension in the anterior bundle in comparison with the tension in the one-bundle (anterior-distal) reconstruction. The peak anterior-bundle tensions with the middle-distal and middle-middle second bundles were 43% and 37% less than the peak bundle tension for the one-bundle reconstruction (p < 0.001 and p = 0.002, respectively). With the exception of the average bundle tension, the tension parameters calculated for the middle bundle decreased as the distance from the articular cartilage increased. The peak tensions for the middle-middle and middle-proximal bundles were 32% and 61% less than that for the middle-distal bundle (p = 0.028 and p = 0.001, respectively). CONCLUSIONS: The femoral position of the second bundle significantly affected the tension in the anterior bundle and the load distribution. A second bundle placed in a middle or distal position resulted in a significant reduction in anterior bundle tension and in cooperative load-sharing (with the bundles functioning together). A proximal second bundle resulted in reciprocal loading (with one bundle functioning in flexion and one in extension), but the tension in the anterior bundle was not different from the tension in the one-bundle reconstruction.

Cadaver↗
PubMed1976

Conduction disturbances of the bundle branches produced by lesions in the nonbranching portion of His bundle.

The present experiments were conducted on isolated dog hearts to demonstrate that conduction disturbances can be induced in the bundle branches by transection of about 50 per cent of the cross-sectional area of the His bundle on the right or left side. The His bundle, the posterior and anterior divisions of left bundle, and the right bundle were exposed by careful dissection, and microelectrode techniques were used to record action potentials from the three bundle branches. Pacing stimuli were applied to the nonbranching portion of His bundle proximal and then distal to the site of transection to study the effect of such lesions on impulse conduction to the bundle branches. It was demonstrated that conduction to the bundle branches was not affected by such lesions in the His bundle at pacing rates slower than 100 per minute; however, conduction disturbances were rate-dependent and manifested at faster pacing rates. In nine out of all 16 experiments, partial or complete block occurred in all three bundle branches regardless of the side of the lesion. In the remaining seven experiments, they were observed in the bundle branch on the same side as the lesion. It was assumed that conduction disturbances of the bilateral bundle branches resulted from decremental conduction in the uncut portion of His at the level of lesion, and those of the ipsilateral branch from the functional failure of transverse crossover connections between the longitudinal His bundle fibers. The results indicate that localized lesions in the nonbranching portion of His bundle can indeed produce the pattern of bundle branch block under certain conditions.

Animals↗
PubMed2007

Double-bundle versus single-bundle anterior cruciate ligament reconstruction: a prospective, randomize clinical study.

Anatomical observation and biomechanical studies have shown that the anterior cruciate ligament (ACL) mainly consists of two distinct bundles, the anteromedial (AM) bundle and posterolateral (PL) bundle. Conventional single-bundle ACL reconstruction techniques have focused on the restoration of the AM bundle while giving limited attention to the PL bundle. The purpose of this prospective, randomized clinical study is to compare the outcomes of ACL reconstruction when using either double-bundle or single-bundle technique and bioabsorbable interference screw fixation, and similar rehabilitation with both techniques. Sixty-five patients were randomized into either double-bundle (n = 35) or single-bundle (n = 30) ACL reconstruction with hamstring tendons and bioabsorbable screw (Hexalon, Inion Company, Tampere, Finland) fixation in both groups. The evaluation methods were clinical examination, KT-1000 arthrometer measurements, radiographic evaluation, as well as International Knee Documentation Committee and Lysholm knee scores. There were no differences between the study groups preoperatively. For an average of 14 months of follow-up (range 12-20 months), 30 patients of the double-bundle group and 29 patients of the single-bundle group were available (91%). At the follow-up, the rotational stability, as evaluated by pivot shift test, was significantly better in the double-bundle group than in the single-bundle group. However, in anterior stability of the knee, there was no significant difference between the groups. None of the patients in the double-bundle group had graft failure, while four patients in the single-bundle group had. In addition, knee scores were equal at the follow-up, and all the results were significantly better at the follow-up than preoperatively, in both groups.

Absorbable Implants↗
PubMed1977

His bundle electrocardiography in manifest and concealed right bundle branch extrasystoles.

His bundle electrocardiography was helpful in the diagnosis of impulse formation in the right bundle branch. Ten patients with narrow QRS complexes had ectopic beats with an "incomplete" left bundle branch pattern and almost simultaneous activation of His bundle and ventricles. Both QRS morphology and H- - V intervals depended on the more proximal or distal location of the ectopic focus. In four patients with "complete" right bundle branch block the morphology of ectopic ventricular complexes and H- - V intervals also depeneded on the presence or absence of retrograde block and differential degrees of forward and/or retrograde conduction delays. Nine patients with "complete" right bundle branch block and four with "complete" left bundle branch block had premature beats which could have originated in the proximal right bundle branch, proximal left bundle branch, or distal His bundle. In one patient with "complete" left bundle branch block, "concealed" His bundle depolarizations (probably originating in an ectopic focus located in the right bundle branch) produced pseudo Type II (Mobitz) A-V block. Although lidocaine appeared to have been more effective in patients with bundle branch block than in those with narrow QRS complexes, further studies are necessary to corroborate this impression.

Adult↗
PubMed1986

Growth and regrowth of actin bundles in Chara: bundle assembly by mechanisms differing in sensitivity to cytochalasin.

Cytochalasin is known to inhibit cytoplasmic streaming rapidly in characean cells without disassembling their actin bundles. Lower cytochalasin concentrations than those needed for streaming inhibition are now shown to disrupt bundle assembly and, over longer periods, assembled bundles. After local wounding, cytochalasin limited bundle regeneration to the production of polygons and straight, discontinuous bundles that rarely connected to bundles outside the wound. The regenerated bundles supported only scattered organelle movements, whereas long, oriented bundles of control cells were connected to those outside the wound and supported bulk endoplasmic streaming. Unwounded Chara plants cultured for up to 2 weeks in 1 microM-cytochalasin maintained normal bundle orientation and rapid cytoplasmic streaming, but the mean number of bundles per file of chloroplasts fell from 5.2 in controls to 2.0 in growing cells and 3.4 in nongrowing cells. These structural effects seem more likely than the streaming inhibition to reflect cytochalasin's in vitro effect of blocking extension at the barbed but not the pointed end of F-actin. In particular, cytochalasin inhibited the extension into the wound of bundles in which only the barbed ends of filaments would be exposed. However, short lengths of isolated bundles grew within the wound and bundle growth in the intact cell continued, albeit in modified form. It is suggested that these examples of continuing bundle growth involve cytochalasin-resistant mechanisms that are not wholly dependent on barbed-end filament growth.

Actins↗
PubMed1975

Contribution of the his bundle recording to the diagnosis of bilateral bundle branch conduction defects.

The participation of intraventricular conduction defects in the AV delays and blocks has been investigated by His bundle electrogram recording in 239 patients with different degrees of AV blocks and QRS enlargement (greater than 0.12 sec). In absence of PR prolongation, the His bundle electrogram can demonstrate intraventricular conduction delay (HV superior to 55 msec) with an increasing frequency in right bundle branch block and right bundle branch with left axis deviation, left bundle branch block and right bundle block with right axis deviation. In cases of first-degree AV block (PR greater than 0.20 sec) delay within the His bundle is present in 20% of the cases and HV prolongation, isolated or associated with an upper conduction defect is demonstrated in 66% of the cases. Second-degree AV block with QRS enlargement in the conducted beats is due to a subnodal lesions of the conducting tissue in 80% of the cases. Wenckebach phenomenon and bundle branch block is as frequent above as below the site of His bundle electrogram recording. Möbitz II block has always an infranodal localization. Third-degree AV block with wide QRS complexes is the consequence of a lesion within the His bundle in 11% and of a complete bilateral bundle branch block in 78% of the cases. Exploration of the AV conduction in acute myocardial infarction with AV block confirms the usual bilateral bundle branch lesion in anterior myocardial necrosis and the AH localization of the AV block in posterior myocardial infarction even in presence of enlarged QRS complexes. Unidirectional block occurs in 19 of the 82 cases of complete anterograde bilateral bundle branch block, with retrograde conduction to the atria in 11 and concealed retrograde conduction in 8 cases.

Bundle of His↗
PubMed1997

Bundle branch reentry ventricular tachycardia with two distinct left bundle branch block morphologies.

INTRODUCTION: Bundle branch reentry ventricular tachycardia (VT) is usually amenable to treatment with radiofrequency ablation. Different QRS morphologies during VT are possible when anterograde ventricular activation is over the left bundle branch. Manifestations of this reentrant tachycardia with more than one QRS morphology with anterograde activation via the right bundle have not been reported and would be unusual due to the more discrete anatomy of the right bundle branch. METHODS AND RESULTS: An electrophysiologic study was conducted in a patient with dilated ventricle and diminished ventricular function with VT. Typical characteristics of bundle branch reentry were noted when VT was induced. The study was notable for the presence of a right bundle recording only during macroreentrant beats or VT and the distal location of the recording. Radiofrequency ablation was performed. Postablation stimulation again induced VT, proven to be of the same bundle branch reentry mechanism but of a different QRS morphology. A second ablation was required for complete ablation of this patient's bundle branch reentry VT. CONCLUSION: In bundle branch reentry utilizing the left bundle as the retrograde limb and the right bundle branch as the anterograde limb of the circuit, VT of more than one distinct morphology can be seen. Careful evaluation to assess for the persistence of VT of the same mechanism is necessary to ensure complete ablation of the reentrant circuit. Preexisting right bundle disease and a dilated heart with more dispersed distal right bundle branches may predispose to such a phenomenon.

Adult↗
PubMed1980

[The bundle branch block anatomically located in HIS bundle (author's transl)].

Bundle branch block (BBB) patterns are commonly considered to represent conduction block in the corresponding bundle branch. However, several histological and experimental studies demonstrated the possibility of a BBB related to an anatomical lesion within the His bundle. Recently there has been demonstrated, also in clinical setting, the possibility of evaluation whether a left bundle branch block (LBBB) is related to an anatomical within such bundle. For this purpose the selective stimulation of the His bundle has been utilized. A distal simulation of such bundle (which can be evaluated by a stimulus-QRS interval shorter than HV interval) normalizing the QRS complexes compresses an anatomical lesion within the proximal His bundle. Such normalization cannot be attributed to a right septum stimulation since the LBBB pattern should be increased instead of disappearing. The Authors think that an anatomical localization within the His bundle can be evaluated only in LBBB. In fact it is possible that a right bundle branch block pattern, if a septal calcification or fibrosis is present, could be normalized also in the presence of an isoelectric line placed between the artificial stimulus and the QRS complex. There is criticized the concept supported by other Authors that normalization of the QRS complex may be related to a summation effect between the sinusal impulse and that artificially induced. In fact such effect can be easy excluded by analizing the temporal relationship between the ventriculograms registered during His bundle stimulation and the atriograms. The clinical implications of the LBBBs in relation with an anatomical lesion within the His bundle are discussed.

Bundle of His↗
PubMed2006

A retrospective study of the midterm outcome of two-bundle anterior cruciate ligament reconstruction using quadrupled semitendinosus tendon in comparison with one-bundle reconstruction.

PURPOSE: The objective of the study was to retrospectively compare the outcome of the first series of a 2-bundle anterior cruciate ligament reconstruction technique using quadrupled semitendinosus tendon with that of a 1-bundle reconstruction technique from 1992 through 1996. TYPE OF STUDY: Case-control study. METHODS: The 1-bundle group consisted of 56 patients with a follow-up period of 24 months or more (average, 46.5 months). The 2-bundle group consisted of 79 patients with a follow-up period of 24 months or more (average, 40.8 months). Manual knee laxity tests, anterior stability with KT-1000 (manual maximum), and knee extension and flexion strength by Cybex were evaluated using an average and standard deviation, and data were categorized according to the International Knee Documentation Committee (IKDC) classification. The Lysholm scale and the subjective recovery scale were also evaluated. RESULTS: A statistically greater number of patients in the 1-bundle group were positive (+ or ++) based on the Lachman test (34% in the 1-bundle group and 13% in the 2-bundle group). The average KT-1000 anterior laxity of 2.7 +/- 2.3 mm in the 1-bundle group was statistically greater than the 1.9 +/- 1.9 mm in the 2-bundle group, with a statistical power between 70% and 80%. The total Lysholm knee scale score was 93 points in both groups, and the subjective recovery score was equivalent, 82% in the 1-bundle group and 86% in the 2-bundle group, respectively. CONCLUSIONS: There was no statistical difference based on the IKDC, Lysholm, and subjective analysis. However, there was a statistical difference in the Lachman test, anterior drawer test, and KT-1000 measurements. LEVEL OF EVIDENCE: Level III.

Adolescent↗
PubMed1997

Hair bundles of sea anemones as a model system for vertebrate hair bundles.

Sea anemones are marine invertebrates that use hair bundles to detect swimming movements of prey. Prey are captured by nematocysts (stinging capsules) that discharge into the prey. To further characterize anemone hair bundles and to compare hair bundles in anemones with hair bundles in vertebrates, we investigated fine structure and cytochemistry of anemone hair bundles. In addition, using a biological assay based on counting nematocysts discharged into vibrating test probes, we examined sensitivity of vibration detection to aminoglycoside antibiotics, Ca(2+)-free seawater, and amiloride. Like vertebrate hair bundles, anemone hair bundles are composed of stereocilia, possess lateral linkages between stereocilia whose preservation for transmission electron microscopy is enhanced by ruthenium red, and possess tip links morphologically similar to vertebrate tip links. Furthermore, vibration-dependent discharge of nematocysts is reversibly inhibited by 10(-4) M streptomycin and abolished by brief exposure to Ca(2+)-free seawater. However, unlike vertebrate hair bundles, anemone hair bundles appear to be insensitive to amiloride since vibration-dependent discharge of nematocysts is unaffected by up to mM amiloride. Thus, anemone hair bundles may serve as a useful model system for vertebrate hair bundles with the interesting feature of being insensitive to amiloride.

Amiloride↗
PubMedDate not supplied

Codominance of the individual posterior cruciate ligament bundles. An analysis of bundle lengths and orientation.

BACKGROUND: It is unclear how each bundle of the posterior cruciate ligament contributes to posterior knee stability. HYPOTHESIS: Changes in bundle orientation and length occur such that neither bundle dominates in restraining posterior tibial motion throughout knee flexion and extension. STUDY DESIGN: Controlled laboratory study. METHODS: Six fresh-frozen cadaveric knees were studied in a joint-testing rig with individual quadriceps and hamstring muscle loading. Kinematic data for the tibia and femur were obtained at knee flexion angles from 0 degrees to 120 degrees. The joint was then disarticulated, and the insertions of the two bundles on the tibia and femur were digitized. RESULTS: Length of the anterolateral bundle increased with increasing knee flexion angle from 10 degrees to 120 degrees. Length of the posteromedial bundle decreased with increasing knee flexion angle from 0 degrees to 45 degrees and increased slightly from 60 degrees to 120 degrees. Length of the anteromedial bundle was significantly less than that of the posteromedial at 0 degrees, 10 degrees, and 20 degrees of knee flexion. The anterolateral bundle was significantly more horizontal at flexion angles of 0 degrees, 10 degrees, 20 degrees, 30 degrees, and 45 degrees (P < 0.05). The posteromedial bundle was more horizontal at 120 degrees. CONCLUSIONS: Changes in orientation take place such that neither bundle dominates in restraining posterior tibial motion throughout knee flexion and extension. CLINICAL RELEVANCE: Double-bundle reconstructions achieve more physiologic knee function.

Aged↗
PubMed1989

Inadvertent catheter-induced right bundle branch block in a patient with preexistent left bundle branch block and recurrent macroreentrant ventricular tachycardia.

This article describes the inadvertent, catheter-induced induction of right bundle branch block resulting not only in transient complete infra-His heart block but also in temporary interruption of the macroreentry circuit of ventricular tachycardia. A patient with preexistent left bundle branch block and spontaneous ventricular tachycardia based upon the bundle branch reentry mechanism underwent electrophysiological testing for the evaluation of sotalol drug efficacy. In search of an optimal His-bundle recording, the manipulation of a 6 Fr quadripolar catheter caused a right bundle branch block, thus advancing the preexistent left bundle branch block to complete heart block. Retrograde ventriculoatrial conduction remained unaffected. The macroreentrant tachycardia with left bundle branch block configuration was no longer inducible. While the patient continued on unchanged sotalol medication (320 mg/d) he required temporary pacing for 16 hours until the block subsided. A subsequent induction attempt demonstrated initiation of the tachycardia. Finally, guided by invasive testing, the patient successfully received amiodarone therapy (300 mg/d). The patient completed an uneventful follow up of 27 months. No progression of conduction delay was observed. This case suggests that the inadvertent induction of right bundle branch block prevents the initiation of ventricular tachycardias relying on bundle branch reentry. Therefore, missed diagnosis or misinterpretation of antiarrhythmic drug efficacy might occur if there is no electrophysiological reevaluation after right bundle branch recovery.

Aged↗