Related Experiment Video

Updated: Aug 19, 2026

Electrophysiological Assessment of Murine Atria with High-Resolution Optical Mapping
08:19

Electrophysiological Assessment of Murine Atria with High-Resolution Optical Mapping

Published on: February 22, 2018

Short atrioventricular Mahaim fibers: observations on their clinical, electrocardiographic, and electrophysiologic

Eduardo Back Sternick1, Márcio L Fagundes, Fernando E S Cruz

  • 1Biocor Instituto, Nova Lima, Brazil. eduardosternick@aol.com

Journal of Cardiovascular Electrophysiology
|February 22, 2005
PubMed
Abstract

Insights

Short atrioventricular (A-V) Mahaim fibers are uncommon preexcitation variants. Catheter ablation is effective for these pathways, though their electrophysiologic properties can be variable.

Area of Science:

  • Electrophysiology
  • Cardiology
  • Medical Devices

Background:

  • Short atrioventricular (A-V) decrementally conducting accessory pathways are rare preexcitation variants.
  • Existing data suggest their decremental properties may not originate from A-V nodal-like tissue.

Purpose of the Study:

  • To compare clinical, electrocardiographic, and electrophysiologic parameters of short A-V Mahaim pathways versus atriofascicular pathways.
  • To assess the efficacy of radiofrequency catheter ablation for these accessory pathways.

Main Methods:

  • Compared 8 patients with short A-V Mahaim pathways (Group A) to 33 with atriofascicular pathways (Group B).
  • Radiofrequency catheter ablation guided by activation mapping (annulus for Group A, "M" potential for Group B).

Main Results:

  • Clear preexcitation persisted in 7/8 Group A patients post-ablation; only 1 had reentrant tachycardia.
  • Automatic rhythms occurred in 4/8 Group A patients during ablation; adenosine blocked Mahaim fibers in 3/5.
  • Group B patients showed minimal preexcitation (72%) and frequent circus movement tachycardia (29/33).
  • Accessory pathway automaticity was noted in 30/33 Group B patients; adenosine blocked atriofascicular pathways in 11/12.

Conclusions:

  • Short, decrementally conducting, right-sided accessory pathways have distinct ECG patterns but non-uniform electrophysiologic properties.
  • Catheter ablation is a successful method for interrupting these pathways.

More Related Videos

Isolation of Atrial Myocytes from Adult Mice08:34

Isolation of Atrial Myocytes from Adult Mice

Published on: July 25, 2019

Related Concept Videos

ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias

Arrhythmia is a condition characterized by an irregular heart rhythm, with ECG changes that differ based on its origin and nature. The types of arrhythmias discussed below include atrial, junctional, and ventricular arrhythmias.Atrial ArrhythmiasPremature Atrial Complexes (PACs): PACs are early atrial beats caused by stress, caffeine, alcohol, electrolyte imbalances, hypoxia, hyperthyroidism, or certain medications (e.g., bronchodilators and decongestants). The ECG shows early P waves with an...
Electrophysiology of Normal Cardiac Rhythm01:19

Electrophysiology of Normal Cardiac Rhythm

The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase of...
Mechanism of Cardiac Arrhythmias01:28

Mechanism of Cardiac Arrhythmias

Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

Bradyarrhythmias are cardiac rhythm disorders characterized by a slower-than-normal heart rate, typically defined as fewer than 60 beats per minute. Some of which are discussed here:Sinus BradycardiaSinus bradycardia presents a heart rate lower than 60 beats per minute, with a regular rhythm originating from the SA node. The ECG typically shows normal P waves preceding each QRS complex, a normal PR interval (0.12 to 0.20 seconds), and a normal QRS duration (0.06 to 0.10 seconds).First-Degree AV...
Dysrhythmias II: Classification of Tachyarrhythmias01:28

Dysrhythmias II: Classification of Tachyarrhythmias

Tachyarrhythmias are a type of dysrhythmia where the heart rate exceeds 100 beats per minute. Here are some common types of tachyarrhythmias:Sinus TachycardiaSinus tachycardia originates from increased impulses from the sinus node, leading to an elevated heart rate. It is often triggered by stress, fever, or exercise.Patients may experience palpitations, a sensation of a racing heart, dizziness, and chest discomfort.Causes and Risk Factors: Common causes include physical exertion, emotional...
Specialized Characteristics of Cardiac Muscles01:27

Specialized Characteristics of Cardiac Muscles

The primary role of cardiac muscles is to propel blood throughout the cardiovascular system. The cardiac muscle cells, or cardiomyocytes, exhibit specialized characteristics that allow them to perform this function.
Cardiac muscle cells are smaller than skeletal muscles, averaging 10–20 mm in diameter and 50–100 mm in length. However, they have large energy demands for continuous contraction and relaxation. This energy is almost exclusively derived from aerobic metabolism of energy reserves in...