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On modern ECG machines, the QTc is given. However, the machines are not always capable in the correct determination of the end of the T wave. Therefore, it is important to check the QT time manually. | On modern ECG machines, the QTc is given. However, the machines are not always capable in the correct determination of the end of the T wave. Therefore, it is important to check the QT time manually. | ||
[[Image:Surawicz.jpg|120px|thumb|right|Dr Surawicz, still active in November 2006, at age 89.]] | [[Image:Surawicz.jpg|120px|thumb|right|Dr Surawicz, founder of the tangent method, still active in November 2006, at age 89.]] | ||
Although QT prolongation is potentially lethal, measurement of the QT interval by physicians is poor as different definitions of the end of the T wave exist.<cite>Viskin</cite> Most QT experts define the end of the T wave as the intersection of the steepest tangent line from the end of the T-wave with the base line of the ECG.<cite>Lepeschkin</cite> This leads to the following stepwise approach: | Although QT prolongation is potentially lethal, measurement of the QT interval by physicians is poor as different definitions of the end of the T wave exist.<cite>Viskin</cite> Most QT experts define the end of the T wave as the intersection of the steepest tangent line from the end of the T-wave with the base line of the ECG.<cite>Lepeschkin</cite> This leads to the following stepwise approach: | ||