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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.

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.

Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers

Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers

Class IV antiarrhythmic drugs, such as verapamil and diltiazem, block calcium channels. They primarily affect the heart, slowing the conduction in calcium-dependent tissues like the SA and AV nodes. These drugs manage reentrant supraventricular tachycardia (SVT) and reduce ventricular rate in atrial flutter/fibrillation.
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...

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...

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...

Cardiac Action Potential

Cardiac Action Potential

Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials

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Calcium-triggered short-coupled polymorphous ventricular tachycardia.

Doreen DeFaria Yeh¹, Jonathan T Lu, Albert Kim

¹Department of Medicine, Electrophysiology, University of California, Electrophysiology Service, 500 Parnassus Avenue, San Francisco, CA 94143-1354, USA. ddefariayeh@hallmarkhealth.org

Pacing and Clinical Electrophysiology : PACE

|May 7, 2010

Summary

This case study highlights an 18-year-old man with syncope due to premature ventricular complexes (PVCs) and polymorphous ventricular tachycardia (PVT). Ablation targeting calcium-triggered ventricular arrhythmias originating from muscle and fascicles was successful.

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Area of Science:

Cardiology
Electrophysiology
Cardiac Arrhythmias

Background:

Syncope in young adults can be caused by various cardiac conditions.
Premature ventricular complexes (PVCs) and ventricular tachycardia (VT) are significant arrhythmias requiring investigation.
Understanding triggers for ventricular arrhythmias is crucial for effective treatment.

Observation:

An 18-year-old male presented with syncope.
He was diagnosed with short-coupled premature ventricular complexes (PVCs) and nonsustained polymorphous ventricular tachycardia (PVT).
Electrophysiology testing identified calcium as a provocative agent for these arrhythmias, while isoproterenol did not trigger them.

Findings:

The earliest triggered event originated from the ventricular muscle, subsequently involving the fascicles.
Radiofrequency ablation successfully targeted these arrhythmogenic areas.
Calcium appears to play a role in triggering these specific ventricular arrhythmias.

Implications:

This case suggests a potential mechanism for calcium-induced ventricular arrhythmias.
Successful ablation provides a therapeutic option for similar cases.
Further research into calcium's role in cardiac electrophysiology may reveal new treatment strategies.