Deciphering T-wave Morphologies on ECGs: The Simplified Egg and Changing Yolk Model and the Importance of the QTp Interval

The Electrocardiogram (ECG) serves as an integral tool in the diagnosis and management of a variety of cardiac diseases. It visualises electrical activity in the heart, offering insights into several cardiac processes, including ventricular repolarisation. The morphology of the T-wave observed on ECGs during this repolarisation phase varies and can be peaked, flat, inverted, or biphasic, each representing different cardiac conditions. Despite their prevalence, the interpretation of these patterns remains challenging. Therefore, we proposed the Simplified Egg and Changing Yolk Model, a novel idea to aid in the understanding of these T-wave morphologies in ECGs. The proposed Simplified Egg and Changing Yolk Model was developed through an analysis of various T-wave morphologies and their corresponding clinical implications. The model was further designed to conceptualise the ST interval and the T-wave as a single unit, contributing to a simplified yet comprehensive understanding of ventricular repolarisation. In this context, the Q-wave start to T-wave peak interval(QTp) was compared to the more commonly used corrected QT-interval (QTc) for assessing the risk of arrhythmia and the effects of medication that prolong the QT-interval. The Simplified Egg and Changing Yolk Model could effectively explain and interpret the variation of ECG patterns associated with ventricular repolarisation. It provided insight into the relevance of deflections seen during this phase. Importantly, the model identified QTp as a more reliable measure than QTc for assessing arrhythmia risk and evaluating medication impacts on the QT-interval. Our model offers a significant enhancement to the understanding of ventricular repolarisation and its manifestation on ECGs. By emphasising the superiority of QTp over QTc in clinical assessment, this model can have significant impact in clinical practice.