Related Experiment Video

Updated: Jun 25, 2026

Analysis of Coronary Vessels in Cleared Embryonic Hearts
08:25

Analysis of Coronary Vessels in Cleared Embryonic Hearts

Published on: December 7, 2016

Exact location of the branching bundle in the living heart

Masamitsu Adachi1, Osamu Igawa, Akio Yano

  • 1Department of Cardiovascular Medicine, Tottori University Hospital, Yonago, Japan.

Pacing and Clinical Electrophysiology : PACE
|March 3, 2009
PubMed

Insights

The earliest His activation (EH) site, indicating the His bundle branching point, is approximately 10 mm proximal to the largest His bundle electrogram (LH) recording site. This finding suggests most His potentials reflect proximal right bundle activation, impacting radiofrequency ablation strategies.

Area of Science:

  • Electrophysiology
  • Cardiac Anatomy

Background:

  • The His bundle electrogram (HBE) is used to localize the His bundle, but distinguishing distal His bundle potential from proximal right bundle branch potential is difficult.
  • Accurate His bundle localization is critical for procedures like radiofrequency ablation in the para-Hisian region.

Purpose of the Study:

  • To pinpoint the His bundle branching point.
  • To compare the branching point location with the site of the largest His bundle electrogram (LH) during sinus rhythm.

Main Methods:

  • Programmed stimulation from the right ventricular apex was performed until retrograde right bundle branch block occurred.
  • The site of earliest His activation (EH) during retrograde conduction was identified as the hypothesized branching point.
  • Measurements included the distance between the LH and EH sites and the atrial-to-ventricular (A/V) amplitude ratio at both sites.

Main Results:

  • The EH site was consistently recorded at the proximal electrode of the His bundle catheter.
  • The mean distance between the EH and LH sites was 9.8 mm.
  • The mean A/V ratio at the EH site (1.01) was significantly higher than at the LH site (0.08).

Conclusions:

  • The His bundle branching point (EH site) is located approximately 10 mm proximal to the site of the largest His bundle electrogram (LH).
  • The high A/V ratio at the EH site suggests it represents proximal right bundle activation.
  • These findings necessitate careful consideration of His potential and A/V ratio, not just amplitude, during para-Hisian radiofrequency ablation.
Abstract

More Related Videos

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing12:45

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

Published on: December 11, 2017

Microdissection and Immunofluorescence Staining of Myocardial Sleeves in Murine Pulmonary Veins08:52

Microdissection and Immunofluorescence Staining of Myocardial Sleeves in Murine Pulmonary Veins

Published on: November 21, 2023

Related Concept Videos

Location and Orientation of the Heart01:13

Location and Orientation of the Heart

The human heart, despite its modest size and weight, is an organ of remarkable strength and endurance. Roughly the size of a fist, the heart weighs between 250 and 350 grams and is nestled within the mediastinum, the medial cavity of the thorax. It extends obliquely for about 12 to 14 cm, resting on the superior surface of the diaphragm. The heart is positioned anterior to the vertebral column and posterior to the sternum, with two-thirds of its mass lying to the left of the midsternal line.
Development of the Heart01:27

Development of the Heart

The development of the human heart, a crucial organ, commences from the mesoderm on the 18th or 19th day after fertilization. This process initiates in the cardiogenic area, a group of mesodermal cells at the embryo's head end, which evolves into elongated strands known as cardiogenic cords. These cords undergo a transformation to form hollow-centered endocardial tubes.
As the embryo undergoes lateral folding, these paired tubes approach each other, merging into a single primitive heart tube by...
Anatomy of the Heart01:27

Anatomy of the Heart

The human heart is made up of three layers of tissue that are surrounded by the pericardium, a membrane that protects and confines the heart. The outermost layer, closest to the pericardium, is the epicardium. The pericardial cavity separates the pericardium from the epicardium. Beneath the epicardium is the myocardium, the middle layer, and the endocardium, the innermost layer. There are four chambers of the heart: the right atrium, the right ventricle, the left atrium, and the left ventricle.
Anatomy of the Heart01:20

Anatomy of the Heart

The heart is a hollow, muscular organ approximately the size of a fist, consisting of four chambers. It is enclosed in the pericardium, a fibrous sac with two layers: the visceral and parietal pericardium, separated by a fluid-filled space containing serous fluid to reduce friction.
The heart has three layers: the innermost endocardium, the muscular myocardium, and the outer epicardium, all working together for optimal cardiac function.
Chambers of the Heart
The heart is made up of four...
Conduction System of the Heart01:20

Conduction System of the Heart

The cardiac conduction system produces and transmits electrical impulses that prompt myocardial contraction, ensuring efficient heart function. This intricate system ensures that the heart beats in a coordinated and efficient manner, beginning with the atria and then the ventricles. The conduction system optimizes cardiac output by maintaining this precise sequence, which is crucial for adequate blood circulation.
This system relies on the unique properties of nodal and Purkinje cells:...
Conduction System of the Heart01:19

Conduction System of the Heart

Autorhythmicity is a term that refers to the heart's inherent ability to generate electrical signals and instigate muscle contractions. This self-regulating conduction system within the heart consists of two key components: the pacemaker cells and specialized conducting cells.
The pacemaker cells are located in two primary nodes: the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node pacemaker cells can autonomously depolarize, triggering an action potential that leads to the...