Differences in left ventricular global function and mechanics in Paralympic athletes with cervical and thoracic spinal cord injuries

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, both systolic and diastolic mechanics were maintained in TETRA, while several indices were lower 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

Orthostatic hypotension among elite wheelchair athletes

Presentation at ISCoS 2009 (International Spinal Cord Society annual research meeting) in Florence, Italy on October 24th, 2009.Medicine, Faculty ofMedicine, Department ofPhysical Medicine and Rehabilitation, Division ofUnreviewedFacult

Cold pressor test in spinal cord injury-revisited

STUDY DESIGN Systematic review. OBJECTIVES A spinal cord injury (SCI) commonly results in alterations of cardiovascular physiology. In order to investigate such alterations, the cold pressor test (CPT) has been used as an established challenge test. This review summarizes the basic physiology underlying a CPT, discusses potential mechanisms responsible for abnormal pressor responses following SCI, and highlights the utility of CPT in the SCI population. SETTING Canada and Switzerland. METHODS We have completed a comprehensive review of studies that have investigated the effect of foot or hand CPT on hemodynamic indices in individuals with SCI. RESULTS Depending on the level of spinal cord lesion and the location of cold application, i.e., above or below the lesion, mean arterial pressure typically increases (ranging between 4 and 23 mmHg), while heart rate responses demonstrated either a decrease or an increase (ranging between -4 and 24 bpm) during CPT. The increase in blood pressure during foot CPT in high-level lesions might not necessarily be attributed to a physiological CPT response as seen in able-bodied individuals, but rather due to a reflexic sympathetic discharge below the level of lesion, known as autonomic dysreflexia. CONCLUSIONS Further investigations in a wider range of individuals with SCI including incomplete injuries might be helpful to examine the ability of CPT assessing the integrity of the autonomic nervous system following SCI. Furthermore, additional autonomic tests are needed to emphasize the integrity of autonomic pathways and to account for the complexity of the autonomic nervous system

The Blood Pressure Pendulum following Spinal Cord Injury: Implications for Vascular Cognitive Impairment

Cognitive impairment following spinal cord injury (SCI) has received considerable attention in recent years. Among the various systemic effects of SCI that contribute towards cognitive decline in this population, cardiovascular dysfunction is arguably one of the most significant. The majority of individuals with a cervical or upper-thoracic SCI commonly experience conditions called orthostatic hypotension and autonomic dysreflexia, which are characterized by dangerous fluctuations in systemic blood pressure (BP). Herein, we review the potential impact of extreme BP lability on vascular cognitive impairment (VCI) in individuals with SCI. Albeit preliminary in the SCI population, there is convincing evidence that chronic hypotension and hypertension in able-bodied individuals results in devastating impairments in cerebrovascular health, leading to VCI. We discuss the pertinent literature, and while drawing mechanistic comparisons between able-bodied cohorts and individuals with SCI, we emphasize the need for additional research to elucidate the mechanisms of cognitive impairment specific to the SCI population. Lastly, we highlight the current and potential future therapies to manage and treat BP instability, thereby possibly mitigating VCI in the SCI population