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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

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.

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...

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...

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 VI: Management of Dysrhythmias

Dysrhythmias VI: Management of Dysrhythmias

Dysrhythmia management involves a multifaceted approach, incorporating pharmacological treatments, medical procedures, surgical interventions, lifestyle modifications, and patient education.Pharmacological ManagementAntiarrhythmic Drugs:Class I (Sodium Channel Blockers): This class includes quinidine and procainamide, which reduce the speed of impulse conduction in the heart, stabilize the cardiac membrane, and control arrhythmias. Quinidine and procainamide are Class IA agents that prolong the...

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Related Experiment Video

Updated: May 15, 2026

Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus

Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus

Published on: April 5, 2011

Early repolarization pattern and risk for arrhythmia death: a meta-analysis.

Su-Hua Wu¹, Xiao-Xiong Lin, Yun-Jiu Cheng

¹Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China. wusuhua@hotmail.com

Journal of the American College of Cardiology

|January 8, 2013

Summary

Early repolarization pattern (ERP) is linked to a higher risk of arrhythmia death, though the overall incidence rate is low to intermediate. Further research is needed to identify specific high-risk subgroups within the general population.

Related Experiment Videos

Last Updated: May 15, 2026

Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus

Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus

Published on: April 5, 2011

Area of Science:

Cardiology
Electrophysiology
Public Health

Background:

Early repolarization pattern (ERP) has been controversially linked to ventricular fibrillation risk.
Prognostic significance of ERP in the general population remains debated.

Purpose of the Study:

To determine the risk and incidence rate of arrhythmia death, cardiac death, and all-cause death in the general population with ERP.
To analyze the association between ERP and mortality outcomes.

Main Methods:

Meta-analysis of 9 relevant studies published up to July 31, 2012.
Inclusion of studies reporting risk ratios and 95% confidence intervals.
Data extraction and synthesis using a random-effects model.

Main Results:

ERP was associated with a 1.70-fold increased risk of arrhythmia death (p = 0.003).
No significant association was found for cardiac death (RR: 0.78) or all-cause death (RR: 1.06).
Absolute risk of arrhythmia death was 70 per 100,000 subjects/year; J-point elevation in inferior leads and notching increased risk.

Conclusions:

ERP is associated with an increased risk of arrhythmia death.
The absolute incidence rate of arrhythmia death in ERP subjects is low to intermediate.
Further studies are required to identify specific ERP subgroups at higher risk for arrhythmia death.