Left ventricular mechanics in untrained and trained males with tetraplegia

Abstract

Reduced left ventricular (LV) function is common in tetraplegia, yet it is unknown whether intrinsic myocardial function is attenuated. This study examined the effect of SCI and exercise-training status on LV mechanics (intrinsic function) and LV systolic/diastolic function by comparing untrained (UT) and trained (TT) individuals with tetraplegia and able-bodied (AB) individuals. Individuals with tetraplegia had a traumatic, chronic, motor-complete cervical spinal cord injury. Nine UT males (40 ± 10 years), 8 TT males (30 ± 5 years), and nine AB males (37 ± 9 years) participated in the study. LV indices were assessed using two-dimensional transthoracic echocardiography, with speckle-tracking analysis for the determination of LV mechanics. For systolic function, stroke volumes were lower in both UT (59 ± 9 mL; p < 0.001) and TT (63 ± 9 mL; p < 0.001) relative to AB (82 ± 11 mL), whereas systolic mechanics were similar across groups. Diastolic function was only reduced in UT, including a lower ratio of early-to-late transmitral filling velocity (1.55 ± 0.28) relative to TT (2.07 ± 0.42; p < 0.05) and AB (2.44 ± 0.61; p < 0.01) and longer isovolumetric relaxation times in UT (101 ± 7 ms) relative to TT (88 ± 11 ms; p < 0.05) and AB (85 ± 6 ms; p < 0.01). Diastolic mechanics (apical circumferential strain rate) were significantly enhanced in TT (3.03 ± 0.83 s–1) compared to AB (1.85 ± 0.65 s–1; p < 0.05). There was a trend (p = 0.062) for a between-group difference in apical radial diastolic strain rate (UT: −2.51 ± 0.83 s–1; TT: −3.92 ± 1.96 s–1; AB: −1.84 ± 0.46 s–1). In tetraplegia, attenuated LV systolic function is not attributed to intrinsic dysfunction, whereas exercise-training status appears to improve both global LV diastolic function and LV mechanics.