Increased right ventricular afterload induces postsystolic thickening of the ventricular septum in nonischemic hearts

Background: We aimed to assess whether myocardial postsystolic thickening (PST) can be induced by an acute increase in right ventricular (RV) afterload and, thus, demonstrate that PST may have a nonischemic cause. Methods. In 8 anesthetized open-chest pigs, radial strains of the interventricular septum (IVS) and left ventricular inferolateral wall were obtained by Doppler tissue echocardiography before and during constriction of the pulmonary artery. Results: After each constriction, RV peak systolic pressure increased from 30 +/- 5 to 57 +/- 8 min Hg (P<.001). Peak systolic radial strain of the IVS decreased from 20.8%+/- 5.3% to 9.5%+/- 4.1% (P=.003), and PST of the IVS increased from 0.3%+/- 0.5% to 6.1%+/- 4.8% (P=.01). The onset of PST started 41 +/- 20 milliseconds after peak negative dP/dt of RV pressure. The inferolateral wall did not show PST. Conclusion: An acute increase in RV pressure causes a significant reduction in peak systolic strain of the IVS associated with the nonischemic appearance of PST.