Revised 03 Dec Accepted 12 Dec Published 18 Jan Abstract We present a case of atrial repolarization waves from an ectopic atrial rhythm mimicking inferior ST segment elevation myocardial infarction in a year-old male patient who presented with left sided chest wall and shoulder pain.
Introduction Clinical conditions other than myocardial ischemia can affect the ST segment resulting in either ST segment elevation or depression. Case Presentation A man in his late 70s presented with a two-week history of constant nonexertional left sided chest pain and neck pain. Figure 1. Figure 2. References G.
Slavich, D. Tuniz, R. Fregolent, and M. View at: Google Scholar F. Holmqvist, J. Carlson, and P. Puletti, M. Curione, F. Pozzar, G. Righetti, and G. Sacher and P. Ari, F. Kahraman, H. Bas, and A. Sapin, M. If the QRS complex only includes an upward positive deflection, then it is an R wave.
The S wave is the first negative deflection after an R wave. Under normal circumstances, the duration of the QRS complex in an adult patient will be between 0. It can also be thought of as the start of the ST segment. The J-point also known as Junction is important because it can be used to diagnose an ST segment elevation myocardial infarction. A T wave follows the QRS complex and indicates ventricular repolarization. Unlike a P wave, a normal T wave is slightly asymmetric; the peak of the wave is a little closer to its end than to its beginning.
When a T wave occurs in the opposite direction of the QRS complex, it generally reflects some sort of cardiac pathology. If a small wave occurs between the T wave and the P wave, it could be a U wave. The biological basis for a U wave is unknown. One of the quickest ways is called the sequence method. To use the sequence method, find an R wave that lines up with one of the dark vertical lines on the ECG paper. If the next R wave appears on the next dark vertical line, it corresponds to heart rate of beats a minute.
The reason for this is that the repolarization wave does not utilize the high-velocity bundle branch and purkinje system, and therefore primarily relies on cell-to-cell conduction. Sometimes a small positive U wave may be seen following the T wave not shown in figure at top of page. This wave represents the last remnants of ventricular repolarization. Inverted T waves or prominent U waves indicates underlying pathology or conditions affecting repolarization.
The QT interval represents the time for both ventricular depolarization and repolarization to occur, and therefore roughly estimates the duration of an average ventricular action potential.
This interval can range from 0. At high heart rates, ventricular action potentials shorten in duration, which decreases the QT interval. Because prolonged QT intervals can be diagnostic for susceptibility to certain types of tachyarrhythmias, it is important to determine if a given QT interval is excessively long.
In practice, the QT interval is expressed as a "corrected QT QTc " by taking the QT interval and dividing it by the square root of the R-R interval interval between ventricular depolarizations. This allows an assessment of the QT interval that is independent of heart rate. Normal corrected Q-c intervals are 0. There is no distinctly visible wave representing atrial repolarization in the ECG because it occurs during ventricular depolarization. Because the wave of atrial repolarization is relatively small in amplitude i.
ECG tracings recorded simultaneous from different electrodes placed on the body produce different characteristic waveforms. Cardiovascular Physiology Concepts Richard E. Klabunde, PhD. Klabunde, all rights reserved Web Design by Jimp Studio.
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