Increased myocardial stiffness is characteristic of many diseases, leads to a loss of diastolic function, and is a cause of diastolic heart failure (DHF). Methods to estimate myocardial stiffness include Shear Wave Elastography (SWE). Currently, ultrasound-based cardiac SWE includes acoustic radiation force (ARF)-based methods; however, the in vivo generation and detection of the shear waves in myocardium is significantly degraded due to limited ARF penetration and clutter noise. Consistently successful cardiac SWE is limited to low BMI patients. The objective of this research is to develop an ultrafast cardiac SWE technique where the shear wave is generated by the mechanical stimulus of the diastolic atrial kick. The amplitude of this wave is at least one order of magnitude higher than ARF-induced shear waves and thus more easily visualized, having a higher chance of success in a broader patient population.