Investigating the QT Interval in a normal population

The purpose of this project is to record the electrical activity of the heart in a group of healthy people over a 24 hour period. The researchers are interested in the interval in the activity of the heart that represents the time it takes for the electrical system to fire an impulse through the ventricles and then recharge. The time it takes for the heart muscle to contract and then recover ready for the next beat is called the QT interval. If this interval is prolonged then the muscle may not be ready when the electrical pulse triggering the next beat reaches it and this may result in erratic heart rhythm.  This QT interval is very important in diagnosing life threatening heart rhythm disorders.  To improve understanding of the QT interval this study will collect information about the QT interval in healthy adults to enable clinicians to better diagnose when the QT interval is not normal.

The objectives of this study are to:

• Investigate the QT interval in a normal population including individual QT variability
• Investigate the relationship between QT and heart rate (RR interval) for individuals in a normal population
• Investigate other factors that many influence the length of the QT interval – age, sex, diurnal variation
• Investigate QT hysteresis in a normal population

Our hypothesis is that about 1 to 3% of the normal population will have an abnormal QT based on the QT nomogram. Little information is known about QT hysteresis in the normal population but previous studies suggest it is on average about 2 minutes.

Would you like to be involved in this study?

We are after healthy adults who have no known heart problems or who are taking any medications known to affect the activity of the heart. Please call (02) 401 43874 or by email ctrg@newcastle.edu.au for more information.