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Related Concept Videos

Electrocardiogram01:29

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...
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

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...
ECG Interpretation of Rhythms01:24

ECG Interpretation of Rhythms

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. When...
Electrocardiogram Fundamentals01:28

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...
ECG Interpretation of Arrhythmias I: Sinus Arrhythmias01:16

ECG Interpretation of Arrhythmias I: Sinus Arrhythmias

Arrhythmias are disturbances in the heart's rhythm that lead to abnormal heartbeats. These irregularities can originate from different parts of the heart and are classified based on their origin and nature.
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism, and...
Correlation between ECG and Cardiac Cycle01:25

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...

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Identifying QT prolongation from ECG impressions using a general-purpose Natural Language Processor.

Joshua C Denny1, Randolph A Miller, Lemuel Russell Waitman

  • 1Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA. josh.denny@vanderbilt.edu

International Journal of Medical Informatics
|October 22, 2008
PubMed
Summary

Natural language processing (NLP) accurately identifies QT prolongation from ECG reports, outperforming machine-generated QTc values. This technology can enhance clinical decision support for detecting cardiac abnormalities.

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Area of Science:

  • Cardiology
  • Medical Informatics
  • Natural Language Processing

Background:

  • QT interval prolongation on electrocardiograms (ECGs) is a risk factor for sudden cardiac death.
  • Medications can cause or worsen QT interval prolongation, necessitating accurate detection for clinical decision support.

Purpose of the Study:

  • To evaluate the accuracy of natural language processing (NLP) in identifying QT prolongation from cardiologist-generated ECG impressions.
  • To compare NLP-based detection with corrected QT (QTc) thresholds reported by ECG machines.

Main Methods:

  • A locally developed NLP tool, KnowledgeMap, was enhanced with negation detection.
  • NLP and regular expression queries were evaluated against manual physician review of 44,318 ECGs.
  • Performance metrics included sensitivity and specificity; manual review investigated false positives.

Main Results:

  • The NLP query achieved a sensitivity of 0.996 and a positive predictive value of 1.000 for QT prolongation.
  • Regular expression queries showed high performance (sensitivity 0.999, PPV 0.982).
  • ECG machine QTc thresholds had significantly lower positive predictive values (0.07-0.25) compared to NLP.

Conclusions:

  • NLP and regular expression queries are more effective than automated ECG machine QTc values for identifying QT prolongation.
  • NLP offers a promising tool for future clinical decision support systems to detect ECG abnormalities.