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Mechanism of Cardiac Arrhythmias

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.

Disturbances in Heart Rhythm

Disturbances in Heart Rhythm

Arrhythmia or dysrhythmia refers to an abnormal heart rhythm caused by a defect in the heart's conduction system. It can cause the heart to beat irregularly, too quickly, or too slowly, leading to symptoms like chest pain, shortness of breath, and fainting. Factors such as stress, caffeine, alcohol, nicotine, cocaine, certain drugs, congenital defects, diseases, and electrolyte abnormalities can trigger arrhythmias.
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...

ECG Interpretation of Arrhythmias I: Sinus Arrhythmias

ECG Interpretation of Arrhythmias I: Sinus Arrhythmias

Arrhythmias are disturbances in the heart's rhythm that lead to abnormal heartbeats. These irregularities can originate from different parts of the heart and are classified based on their origin and nature.
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism, and...

Dysrhythmias III: Characteristics of Dysrhythmias

Dysrhythmias III: Characteristics of Dysrhythmias

Dysrhythmias, also known as arrhythmias, are irregular heart rhythms that result from abnormal electrical activity in the heart, affecting its ability to circulate blood efficiently. Tachyarrhythmias, a subset of dysrhythmias, are characterized by abnormally fast heart rates exceeding 100 beats per minute. Here are some types of tachyarrhythmias with their distinct ECG features:Sinus Tachycardia:Sinus tachycardia presents a regular heart rhythm with an increased rate of 101-180 beats per minute.

Dysrhythmias V: Evaluating Dysrhythmias

Dysrhythmias V: Evaluating Dysrhythmias

Dysrhythmias, also known as arrhythmias, are disturbances in the heart's rhythm that range from benign to life-threatening. A thorough evaluation is crucial for appropriate management and involves a comprehensive medical history, physical examination, and various diagnostic tests.Medical HistorySymptoms: Collect detailed information on palpitations, dizziness, syncope, chest pain, and fatigue. Note their onset, frequency, and triggers.Previous Cardiac Issues: Document any history of heart...

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

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...

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Cardiac Magnetic Resonance Imaging at 7 Tesla

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Magnetocardiography: ventricular arrhythmias

R Fenici¹, G Melillo

¹Clinical Physiology, Cardiovascular Biomagnetism Center, Catholic University, Rome Italy.

European Heart Journal

|September 1, 1993

Summary

Magnetocardiography (MCG) non-invasively maps ventricular arrhythmias, aiding in localizing the arrhythmogenic substrate and identifying sudden death risk. This technique shows promise for guiding targeted cardiac interventions.

Area of Science:

Cardiology
Biomagnetism
Medical Imaging

Background:

Magnetocardiography (MCG) has been used since 1985 for severe ventricular arrhythmias.
It aids in non-invasive localization of arrhythmogenic substrates and risk stratification for sudden cardiac death.
MCG investigates electrogenetic abnormalities and detects late magnetic fields, quantifying repolarization/depolarization issues.

Purpose of the Study:

To review the applications of MCG in cardiac electrophysiology.
To describe experience with MCG in 35 patients with Lown class 3+ ventricular arrhythmias.
To localize the origin of ventricular arrhythmias and calculate the Relative Smoothness (RS) Index.

Main Methods:

Utilized MCG for non-invasive localization of arrhythmogenic substrates.

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Studied 35 patients with severe ventricular arrhythmias (Lown class 3 or higher).

Calculated the Relative Smoothness (RS) Index to assess repolarization/depolarization abnormalities.

Main Results:

Achieved reproducible 3D MCG localization of ventricular extrasystoles and tachycardia with ~10 mm accuracy.
The RS index was significantly lower in patients with cardiomyopathy or history of sudden death.
MCG localization of arrhythmogenic substrate proved feasible for guiding invasive procedures.

Conclusions:

MCG is a valuable tool for non-invasive localization of arrhythmogenic substrates in ventricular arrhythmias.
MCG findings can guide targeted invasive electrophysiology, biopsy, and ablation procedures.
Further investigation of the RS index is needed to confirm its clinical reliability.