What is the role of ECG in the workup of tetralogy of Fallot (TOF)?

Updated: Nov 13, 2018
  • Author: Shabir Bhimji, MD, PhD; Chief Editor: Yasmine S Ali, MD, FACC, FACP, MSCI  more...
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The electrocardiogram (ECG) will usually show the presence of right ventricular (RV) hypertrophy with a right bundle branch block. The longer the QRS interval, the larger will be the RV mass and volume. Furthermore, when the QRS interval is longer than 180 milliseconds (ms), it is a significant marker for the development of ventricular arrhythmias and sudden death. [22]

Another ECG feature that is also known to predict the risk for ventricular arrhythmias and sudden death is the rate of change in the QRS interval. A relatively fast increase (>3.5 ms/year) is associated with a higher risk of death. A rapid change in the rate of change is also a significant event in the absence of prolongation of the QRS interval. Finally, variation in the heart rate is also a marker for sudden death in these patients. [22]

In other patients, the ECG will reveal atrial tachycardia or atrial fibrillation.

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