Left Ventricular Untwisting in Restrictive and Pseudorestrictive Left Ventricular Filling: Novel Insights into Diastology

Background: Conceptually, an ideal therapeutic agent should target the underlying mechanisms that cause left ventricular (LV) diastolic dysfunction. The objective of our study was to gain further insight into the mechanics of diastology by comparison of LV untwisting measured by speckle tracking echocardiography (STE) in young healthy adults with normal and "pseudorestrictive" LV filling, and dilated cardiomyopathy (DCM) patients with "true restrictive" LV filling. Methods: The study comprised 20 healthy volunteers with a Doppler LV-inflow pattern compatible with restrictive LV filling but a diastolic early phase filling velocity/early diastolic velocity of the mitral annulus (E/Em) ratio < 8 ("pseudorestrictive"), 20 for age and gender-matched healthy volunteers with normal LV filling and an E/Em ratio < 8, and 10 DCM patients with "true restrictive" LV filling and an E/Em ratio > 15. LV untwisting parameters were determined by STE. Results: Compared to healthy subjects, DCM patients had decreased peak diastolic untwisting velocity (-62 +/- 33 degrees/s vs -113 +/- 25 degrees/s, P < 0.01) and untwisting rate (-15 +/- 9 degrees/s vs -51 +/- 24 degrees/s, P < 0.01). Compared to healthy subjects with normal LV filling, healthy subjects with "pseudorestrictive" LV filling had increased peak diastolic untwisting velocity (-123 +/- 25 degrees/s vs -104 +/- 30 degrees/s, P < 0.05) and untwisting rate (-59 +/- 23 degrees/s vs -44 +/- 22 degrees/s, P < 0.05). Conclusion: Faster LV untwisting plays a pivotal role in the rapid early diastolic filling occasionally seen in young healthy individuals. In contrast, in DCM patients untwisting is severely delayed and this impairment to utilize suction may reduce LV filling. (Echocardiography 2010;27:269-274)