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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...

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

Class III antiarrhythmic drugs are a group of medications that can prolong action potentials in the heart. They achieve this by blocking potassium channels or enhancing inward currents from sodium channels. However, these drugs have a unique property of "reverse use-dependence," which is most pronounced at slower heart rates and can lead to torsades de pointes—a specific type of arrhythmia. However, it is essential to note that excessive QT interval prolongation—a measure of the heart's...

Dysrhythmias II: Classification of Tachyarrhythmias

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...

Dysrhythmias IV: Characteristics of Bradyarrhythmias

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 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.

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

Class I antiarrhythmic drugs are used to treat various types of arrhythmias or irregular heart rhythms. These drugs block the sodium (Na+) channels in the cardiac cells, thereby affecting the movement of electrical impulses across the heart. Class I antiarrhythmic drugs are divided into three subgroups: Class IA, Class IB, and Class IC, each with distinct mechanisms of action and effects on the heart.
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...

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Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation

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Long and short QT syndrome.

B Borchert¹, T Lawrenz, C Stellbrink

¹Städtisches Klinikum Bielefeld Mitte, Abteilung für Kardiologie und internistische Intensivmedizin, Teutoburger Strasse 50, 33604 Bielefeld, Germany.

Herzschrittmachertherapie & Elektrophysiologie

|January 11, 2007

Summary

Molecular genetic analysis has advanced understanding of inherited long QT syndrome (LQTS) and short QT syndrome (SQTS), which stem from cardiac ion channel defects. This knowledge impacts clinical management of these arrhythmogenic conditions.

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Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation

Published on: January 16, 2019

Electrocardiogram Recordings in Anesthetized Mice using Lead II

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Published on: June 20, 2020

Area of Science:

Cardiology
Genetics
Molecular Biology

Background:

Inherited arrhythmogenic syndromes like long QT syndrome (LQTS) and short QT syndrome (SQTS) are characterized by abnormal QTc intervals.
These conditions arise from cardiac ion channel dysfunctions, termed
Genetic heterogeneity is observed in the molecular pathways linking genetic defects to phenotypic expression.

Purpose of the Study:

To review the molecular basis of LQTS and SQTS.
To highlight the impact of molecular genetics on the clinical management of these channelopathies.

Main Methods:

Review of current literature on molecular genetics of LQTS and SQTS.
Analysis of the relationship between genetic defects and clinical phenotypes.

Main Results:

Molecular genetic analysis has significantly expanded knowledge of LQTS and SQTS.
Understanding of cardiac ion channel dysfunction in these syndromes has grown.
Genetic heterogeneity influences disease presentation and management.

Conclusions:

Molecular genetics provides critical insights into the pathogenesis of LQTS and SQTS.
Advances in genetic understanding are transforming the clinical management of these inherited arrhythmias.