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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

Electrocardiogram

Electrocardiogram

An electrocardiogram (ECG or EKG) is a critical diagnostic tool that records the electrical signals produced by the heart during each heartbeat. This recording is achieved through electrodes placed strategically on the arms, legs, and chest. The electrocardiograph amplifies these signals and produces 12 distinct tracings, offering a comprehensive understanding of the heart's electrical activity.
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...

Electrocardiogram Fundamentals

Electrocardiogram Fundamentals

Introduction
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin to...

Correlation between ECG and Cardiac Cycle

Correlation between ECG and Cardiac Cycle

The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...

Electrophysiology of Normal Cardiac Rhythm

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...

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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Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System

Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System

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Atrial repolarization: its impact on electrocardiography.

Rory Childers¹

¹Department of Medicine, Section of Cardiology, University o f Chicago, IL, USA. rchilder@medicine.bsd.uchicago.edu

Journal of Electrocardiology

|October 25, 2011

Summary

This summary is machine-generated.

The atrial repolarization (T(a)) wave, often unseen in normal heart rhythms, can mimic injury during stress tests. Its higher voltage in retrograde P waves is crucial for diagnosing acute atrial infarction.

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Area of Science:

Cardiology
Electrophysiology
Cardiac Diagnostics

Background:

The repolarizing T(a) wave is typically not visible in normal sinus rhythm.
Its visibility is dependent on conditions like long P-R intervals or complete atrioventricular block, often with low voltage.
The T(a) wave can significantly impact the interpretation of inferior lead ST deviation during stress testing.

Purpose of the Study:

To elucidate the diagnostic significance of the T(a) wave in various cardiac conditions.
To investigate the T(a) wave's influence on electrocardiographic findings, particularly ST deviation.
To highlight the T(a) wave's role in diagnosing acute atrial infarction.

Main Methods:

Analysis of electrocardiographic recordings under different rhythm conditions (sinus rhythm, retrograde P waves).
Evaluation of T(a) wave characteristics, including voltage and visibility.
Correlation of T(a) wave findings with stress test results and clinical diagnoses.

Main Results:

The T(a) wave is often unseeably low in normal sinus rhythm but can be influenced by long P-R intervals or AV block.
Inverted or retrograde P waves exhibit a higher voltage T(a) wave, potentially simulating inferior myocardial injury.
Specific atrial action potential properties, like resistance to hyperkalemia and supernormality, support specialized internodal tracts.

Conclusions:

The T(a) wave plays a critical role in interpreting stress test ST deviations.
The T(a) wave's characteristics in retrograde P waves can be misleading, mimicking infarction.
The T(a) wave is essential for the diagnosis of acute atrial infarction.