Differences in Left Ventricular Global Function and Mechanics in Paralympic Athletes with Cervical and Thoracic Spinal Cord Injuries

Abstract

Following a spinal cord injury, there are changes in resting stroke volume (SV) and its response to exercise. The purpose of the following study was to characterize resting left ventricular structure, function, and mechanics in Paralympic athletes with tetraplegia (TETRA) and paraplegia (PARA) in an attempt to understand whether the alterations in SV are attributable to inherent dysfunction in the left ventricle. This retrospective study compared Paralympic athletes with a traumatic, chronic (>1 year post-injury), motor-complete spinal cord injury (American Spinal Injury Association Impairment Scale A-B). Eight male TETRA wheelchair rugby players (34 ± 5 years, C5-C7) and eight male PARA alpine skiers (35 ± 5 years, T4-L3) were included in the study. Echocardiography was performed in the left lateral decubitus position and indices of left ventricular structure, global diastolic and systolic function, and mechanics were derived from the average across three cardiac cycles. Blood pressure was measured in the supine and seated positions. All results are presented as TETRA vs. PARA. There was no difference in left ventricular dimensions between TETRA and PARA. Additionally, indices of global diastolic function were similar between groups including isovolumetric relaxation time, early (E) and late (A) transmitral filling velocities and their ratio (E/A). While ejection fraction was similar between TETRA and PARA (59 ± 4 % vs. 61 ± 7 %, p = 0.394), there was evidence of reduced global systolic function in TETRA including lower SV (62 ± 9 ml vs. 71 ± 6 ml, p = 0.016) and cardiac output (3.5 ± 0.6 L/min vs. 5.0 ± 0.9 L/min, p = 0.002). Despite this observation, several indices of systolic and diastolic mechanics were maintained in TETRA but attenuted in PARA including circumferential strain at the level of the papillary muscle (−23 ± 4% vs. −15 ± 6%, p = 0.010) and apex (−36 ± 10% vs. −23 ± 5%, p = 0.010) and their corresponding diastolic strain rates (papillary: 1.90 ± 0.63 s−1 vs. 1.20 ± 0.51 s−1, p = 0.028; apex: 3.03 ± 0.71 s−1 vs. 1.99 ± 0.69 s−1, p = 0.009). All blood pressures were lower in TETRA. The absence of an association between reduced global systolic function and mechanical dysfunction in either TETRA or PARA suggests any reductions in SV are likely attributed to impaired loading rather than inherent left ventricular dysfunction.

Patients with chronic high spinal cord injury can be safely treated with neuromuscular electrical stimulation: cardiovascular function is unaffected

“…Systolic pressure became higher during the test itself (fatigue) due to the increasing speed imposed by the test and consequently the increase of the force of ventricular contraction and cardiac output during the exercise. 19 On the other hand, diastolic pressure was lower at the end of the exercise itself. The values were significant in relation to the phase and were consistent with a drastic drop in resistance to peripheral blood flow during exercise.…”

“…The values were significant in relation to the phase and were consistent with a drastic drop in resistance to peripheral blood flow during exercise. 19 …”

Left Ventricular Mechanics in Untrained and Trained Males with Tetraplegia

“…Cardiac adaptations following a spinal cord injury (SCI) have been well documented by echocardiography studies over the past few decades. While changes in both left ventricular (LV) structure and global LV systolic and diastolic function have been observed in individuals with tetraplegia and paraplegia, [1][2][3][4][5][6][7][8][9][10][11][12] there appears to be a lesion level-dependent effect of SCI on cardiac function with the most severe changes occurring in individuals with tetraplegia. In particular, reductions in global LV systolic function including stroke volume (SV), cardiac output ( ) and ejection fraction (EF) have been documented in both untrained individuals with tetraplegia (UT) and trained individuals with tetraplegia (TT) relative to either individuals with paraplegia or able-bodied (AB) controls.…”

“…In particular, reductions in global LV systolic function including stroke volume (SV), cardiac output ( ) and ejection fraction (EF) have been documented in both untrained individuals with tetraplegia (UT) and trained individuals with tetraplegia (TT) relative to either individuals with paraplegia or able-bodied (AB) controls. 1,5,8,11,12 Conversely, global LV diastolic function appears to be influence by exercise-training status whereby global LV diastolic dysfunction in present in UT while Paralympic athletes with tetraplegia (TT) have global LV diastolic values comparable to AB individuals. 11 While it has long been speculated that the differences in global function are attributed to reductions in loading, it still remains to be determined whether inherent dysfunction in the myocardium itself is a contributing factor.…”

“…16 We recently demonstrated that LV mechanics were not affected in TT when compared to Paralympic athletes with paraplegia. 12 However, it remains to be determined how LV mechanics are affected in UT, in addition to how the values in UT and TT compare to a control sample of AB individuals. Therefore, the primary objective of this study was to examine the effect of SCI on both LV mechanics and indices of global LV systolic and diastolic function by comparing individuals with tetraplegia and AB individuals.…”