A new anatomical view on the vector cardiogram: The mean temporal-spatial isochrones.

AIM: This proof of principle study aims to show the direct relationship between cardiac anatomy and the mean cardiac activation path as captured by the 12 lead ECG derived mean temporal-spatial isochrones (mean TSI) path.

METHODS: To obtain the mean TSI signal a vector cardiographic (VCG) signal is constructed from the 12 lead ECG. The construction of the VCG signal uses a model of the heart and torso with patient specific electrode extracted from a 3D photo. The propagation of the activation through the heart is captured by estimating the mean of a cardiac activation isochrone using this VCG signal. The mean TSI signal is related to the heart model in a standard view using 3 orthogonal heart views, instead of the standard body related orthogonal planes.

RESULTS: The mean TSI was computed for 4 patients with the ECG containing ectopic activations like Premature ventricular contractions (PVCs) or pacemaps, and normal His-Purkinje activations. For each patient, a specific model with known electrode positions was available. For each activation, the mean TSI was shown in relation to the cardiac anatomy. The region of origin of the PVC or pacemap could easily be localized from these views. Also the initial trans-septal activation for normal His-Purkinje activations could easily be detected and related to the septum.

CONCLUSION: This proof of principle study showed that the mean path of cardiac activation can be derived from the ECG and related to standard orthogonal heart views: LAO, RAO, and 4 chambers. This new methodology might help to improve the diagnostic value of the ECG, as the interpretation of the mean TSI is easier to be related to the cardiac anatomy, also for less experienced physicians.