Resting ECGs (section: physical state) were taken in Lifelines participants aged 13 years and older during:

• 1A Visit 1 (n = ~156.000, including ~5600 children)
• 2A Visit 1 (n = ~112.000, no children))
• 3A Visit 1

The 12-lead resting ECG measures electrical activity of the heart during rest, summarized in 12 leads.
The ECG provides many (>400) different variables at once, both quantitative and qualitative traits. These include duration, voltage and configuration characteristics. For example, information is provided of the cardiac rhythm, heart rate, the function of the sinoatrial and the atrioventricular node, atrial size, left ventricular mass, and repolarisation time (e.g. QT time).

Welch Allyn CardioPerfekt Workstation ecg_manual.pdf
Welch Allyn CardioPerfect Workstation Software ecg_software_manual.pdf
DT100 vacuum units (suction electrode system).

Electrodes were placed with conduction spray on ten clean spots at the abdomen and left side of the chest of lying participants (see illustration). In case of dextrocardia, the electrodes were mirrored.

All ECGs were checked by the research nurse and the Welch Allyn algorithm using CardioPerfekt software (see flow chart). ECG deviations (atrium fibrillation, atrium flutter, bradycardia, tachycardia, infoaction, acute ischemia, ST elevation, Wolff Parkinson White Syndrome, bigemenia, Left Bundle Branch Block, >1 premature ventricular contraction, second or third grade AV-block, pacemaker) were reported to a cardiologist.

The ECG resulted in the following variables: