In dyssynchronous hearts contraction patterns (CP) are heterogeneous due to non-simultaneous activation of the cardiac muscle. Any stress generated in one part of the wall reflects in all other parts of the wall therefore, the earlier activated region causes stretch in later activated regions. The CP are measured non-invasively with MRI-tagging or Ultrasound speckle tracking. Most informative are mid-wall circumferential strains, which are determined for given location in the LV wall.

CP are studied to obtain maps of the LV activation time and parameters of global ventricular function. The maps and the parameters are used to improve selection of patients for cardiac resynchronisation therapy (CRT). Maps are obtained from the prominent events in the CP like the onset of shortening time, peak shortening time and magnitude of shortening.

The parameters of global ventricular function consider interplay of CP in different regions to evaluate the coherence and the reserve capacity of the LV contraction. One of them is internal stretch fraction (ISF), which is definedas the amount of stretch relative to the amount of shorteningduring ventricular ejection. ISF isbetter predictor of reverse remodeling after CRT than differencesin time to onset and time to peak shortening.

An alternative to mapping prominent events in CP is decomposition of patterns with respect to activation time. For this purpose, a lumped parameter model (CircAdapt) is used to simulate CP in dyssynchronous hearts. The activation time map is determined with reverse modelling by using measured CP.

In the cardiac muscle, on top of altered activation times also the contractility may differ in regions. This adds a new dimension in the complexity of CP and imposes challenges in mapping both simultaneously.