An Open-Source Algorithm for Standardized Bullseye Visualization of High-Resolution Cardiac Ventricular Data

Job Stoks1, Uyen Chau Nguyen2, Ralf Peeters1, Paul Volders1, Matthijs Cluitmans1
1Maastricht University, 2Cardiovascular Research Institute Maastricht (CARIM)


Processing electro- or mechano-anatomical results from cardiac ventricles for scientific purposes in a structured manner can be challenging. Providing a clear, unified graphical representation of data by standardization, whilst still considering inter-individual anatomical aspects, could aid researchers in gain-ing more insight from complex data. We developed UNISYS (Universal veN-trIcular bullSeYe viSualization): an algorithm to process the geometry of cardiac ventricular data and display them uniformly in a 2D high-resolution circular representation (bullseye plot).

The algorithm provides a semi-automated approach, programmed in MATLAB and is suitable for invasive and non-invasive electro- or mechani-cal-anatomical mapping data of the ventricles. Through the circular repre-sentation it employs, this works either for the epicardium for both ventricles simultaneously, or for the endocardium of one ventricle separately. The in-put geometry consists of vertices, and each vertex should contain an associ-ated value to display (e.g. activation time, repolarization time, voltage, strain etc). Firstly, the user denotes the apex, base and lateral right ventricle through a graphical user interface. Subsequently, the ventricles are rotated parallel to the heart axis, with the apex pointing downwards. Secondly, the ven-tricles are morphed to a cone shape, with increasing radius from apex to base, converting cartesian to polar coordinates. Thirdly, the cone is translated into a 2D circular disk. Lastly, the initial values associated with each vertex in the ventricles are colour-coded in 2D, with apical values displayed in the centre and basal values in the outer ring. By visuali-zation of the individual points’ contribution to the bullseye plot, a scientifi-cally correct interpretation is warranted.

The algorithm is now freely available through the consortium for ECG imaging to encourage its widespread use and contribute to the scientific de-velopment in the field of cardiac mapping, while preserving scientifically accurate interpretation of the data.