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Related Concept Videos

Electrocardiogram01:29

Electrocardiogram

7.3K
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...
7.3K
Correlation between ECG and Cardiac Cycle01:25

Correlation between ECG and Cardiac Cycle

14.1K
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...
14.1K
Cardiac Action Potential01:30

Cardiac Action Potential

8.1K
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
8.1K
Dysrhythmias III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

616
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...
616
Electrocardiogram Fundamentals01:28

Electrocardiogram Fundamentals

1.8K
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...
1.8K
ECG Interpretation of Rhythms01:24

ECG Interpretation of Rhythms

17.1K
An electrocardiogram (ECG)graphically represents the heart's electrical activity on ECG paper or a monitor.
Components of the Electrocardiogram
The primary components of a normal ECG waveform in Normal sinus rhythm(NSR) include the P wave, PR interval, QRS complex, ST segment, T wave, and occasionally a U wave.
ECG waveforms are divided by vertical and horizontal lines at standard intervals.
The horizontal axis measures time and rate, and the vertical axis measures amplitude or voltage....
17.1K

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Updated: Mar 14, 2026

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis
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A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis

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Spike on T wave! What went wrong?

Pasquale Crea1, Giuseppe Picciolo1, Teresa Crea2

  • 1Cardiology Unit, Department of Clinical and Experimental Medicine, University Hospital of Messina, Messina, Italy.

Journal of Electrocardiology
|October 7, 2016
PubMed
Summary
This summary is machine-generated.

Pacemaker malfunction caused by intermittent atrial and ventricular undersensing led to dizziness and fatigue in an elderly patient. This highlights the need for careful pacemaker monitoring and adjustment.

Keywords:
Atrial undersensingDual chamber deviceR on TVentricular undersensing

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Area of Science:

  • Cardiology
  • Biomedical Engineering
  • Electrophysiology

Background:

  • Dual chamber pacemakers are crucial for managing bradyarrhythmias.
  • Pacemaker sensing issues can lead to suboptimal therapy and patient symptoms.

Observation:

  • An 80-year-old male with a dual chamber pacemaker presented with dizziness and fatigue.
  • Electrocardiogram (ECG) revealed sinus rhythm with variable atrioventricular intervals and mixed spontaneous/paced ventricular complexes.
  • A spike on the T wave suggested ventricular undersensing.

Findings:

  • Telemetry-guided pacemaker interrogation identified intermittent atrial undersensing.
  • The combination of atrial and ventricular undersensing likely contributed to the patient's symptoms.

Implications:

  • This case underscores the importance of comprehensive pacemaker evaluation, including both atrial and ventricular channels.
  • Inconsistent sensing can necessitate device reprogramming or lead revision.
  • Accurate pacemaker function is vital for preventing adverse cardiovascular events and improving patient quality of life.