Geometrical and functional cardiac changes after cardiac surgery: a phisiopatological explanation based on speckle tracking.

Abstract

Cardiac surgery induces geometrical and functional changes, which are not clearly explained. Objective: to investigate the physiopathology of the heart after cardiac surgery using advanced techniques of echocardiography. Thirty patients undergoing cardiac surgery had echocardiographic study prior and after surgery. Left and right ventricular (RV) longitudinal displacement and strain were studied with speckle-tracking. Using longitudinal displacement, we defined a static longitudinal reference-point (sLRP) to which the other segments moved during systole. Transversal displacement and global function were determined by conventional-echo. Left and RV segments showed systolic longitudinal displacement towards the apex, which was the sLRP before surgery; and towards the medium segment of lateral RV-wall one week after surgery. The displacement of basal RV segment towards this sLRP was smaller, causing decreased TAPSE. Apical segments showed an inverse displacement towards the new sLRP, and septum displacement was decreased or inverted towards the lateral RV-wall, causing paradoxus septal motion. RV-wall longitudinal strain was reduced (- 23.1 ± 8.6 vs. - 14.6 ± 5.3;p < 0.001), RV transversal fractional shortening was increased (36.5 ± 10.5 vs. 41.7 ± 13; p = 0.011), and the RV fractional area change was unchanged (46.7 ± 9.5 vs. 47.8 ± 11.7; p = 0.625). The medium segment of RV lateral wall, in contact with sternotomy, remains static after surgery and acts as a new sLRP towards which the rest of segments move, explaining the reduction of TAPSE and paradoxus septal motion. The longitudinal strain of the lateral RV-wall gets impaired, but an increase of transversal motion maintains global RV function.