Electrocardiogram

An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart in the form of a continuous strip graph. It is the prime tool in cardiac electrophysiology, and has a prime function in screening and diagnosis of cardiovascular diseases.

ECG measures

QT interval

The QT interval is measured from the beginning of the QRS complex to the end of the T wave. The QT interval as well as the corrected QT interval are important in the diagnosis of long QT syndrome and short QT syndrome. The QT interval varies based on the heart rate, and various correction factors have been developed to correct the QT interval for the heart rate.

Related Topics:
QT interval - Long QT syndrome - Short QT syndrome

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The most commonly used method for correcting the QT interval for rate is the one formulated by Bazett and published in 19201. Bazett's formula is QTc = rac{QT}{sqrt {RR} }, where QTc is the QT interval corrected for rate, and RR is the interval from the onset of one QRS complex to the onset of the next QRS complex, measured in seconds. However, this formula tends to not be accurate, and over-corrects at high heart rates and under-corrects at low heart rates.

Related Topics:
1920 - QTc

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