Intervals
Results:
Short QT Interval: DDx
Key Points: Short QT Interval: A QT interval is considered short when the corrected QT (QTc) interval is less than 350 ms. A short QT interval on the ECG can…
Prolonged QT Interval: DDx
Key Points: The QT interval reflects the time it takes for total ventricular depolarization and repolarization (Q wave onset to T wave end). QT prolongation increases the risk of torsades…
QT Interval: Basics
Key Points Definition: QT = onset of QRS → end of T; reflects total ventricular depolarization + repolarization. Rate correction (QTc): Use corrected QT interval, because QT shortens with faster…
PR Interval: Basics
Key Points Definition: The PR interval runs from P-wave onset to the first ventricular deflection (Q or R). It reflects atrial depolarization plus AV node–His–Purkinje conduction delay. Normal range: 120–200…
Waveforms, Segments, & Intervals: Basics
Key Points ECGs display voltage changes across the cardiac cycle, captured as waveforms, segments, and intervals. Waveforms represent depolarization or repolarization events. Segments are baseline connections between waveforms, usually representing…
Intervals
Key Points Definition: ECG intervals measure the duration of electrical activity across different parts of the cardiac cycle. They reflect conduction times through the atria, AV node, ventricles, and repolarization…
Short QT Syndrome
Key Points Short QT Syndrome (SQTS) is a rare condition characterized by a shortened QT interval on the ECG, increasing the risk of atrial and ventricular arrhythmias, including sudden cardiac…
ECG Foundations: Waveforms, Intervals, Conduction, and Leads
Key Points: Electrocardiography Defined: An ECG records the heart’s electrical activity in real time, offering a rapid window into rate, rhythm and conduction. The ECG measures changes in voltage between…
Congenital Long QT Syndrome
Key Points Congenital Long QT Syndrome (LQTS) is a group of genetic disorders characterized by a prolonged QT interval on ECG, leading to an increased risk of ventricular arrhythmias and…
Acquired Long QT Syndrome
Key Points Acquired Long QT Syndrome (LQTS) is the most common form of LQTS, resulting from medications, electrolyte disturbances, or underlying medical conditions. High-risk factors include the use of multiple…
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