Background: Strain rate imaging is a new and intriguing way of displaying myocardial deformation properties by means of echocardiography. With high frame rate strain rate imaging we observed a spatial inhomogeneity in diastolic longitudinal strain rates in healthy persons. A base-to-apex time delay in diastolic lengthening could be seen both in early diastole and at atrial contraction.
Methods and results: We investigated this consistent finding and its dependence on loading conditions in 20 healthy volunteers. Propagation velocities of lengthening of 91 +/- 31 cm/s (E-wave) and 203 +/- 11 cm/s (A-wave) at rest (equal to time delays of 104 +/- 29 ms and 56 +/- 24 ms, respectively) increased significantly to 101 +/- 27 cm/s (E) and 283 +/- 17 cm/s (A) with lifting the volunteers' legs. Applying nitroglycerin sublingually and sitting upright significantly decreased propagation velocities (E-wave 76 +/- 20 cm/s, A-wave 172 +/- 93 cm/s and E-wave 66 +/- 17 cm/s, A-wave 150 +/- 64 cm/s, respectively). Free lateral walls showed a lower propagation velocity than septal walls.
Conclusion: We conclude that the propagation velocities of left ventricular lengthening waves are dependent on preload changes and increase with increasing preload.