Key result
Paraplegic hypertensive rats had a 35% lower effective refractory period, 62% lower electrical stimulation threshold to induce ventricular arrhythmias, and 84% higher cardiac sympathetic tonus.
Why the study?
Does paraplegia increase susceptibility to ventricular arrhythmias in hypertensive rats?
Does paraplegia increase susceptibility to ventricular arrhythmias in hypertensive rats?
In a hypertensive rat model, paraplegia significantly increases cardiac sympathetic tonus and susceptibility to ventricular arrhythmias.
Answers are grounded in this paper and cite their sources.
May increase arrhythmia susceptibility in paraplegic hypertensive models; leaves open translation to human risk or practice.
Individuals with spinal cord injury (SCI) between thoracic vertebrae four (T4) and five (T5) have elevated levels of sympathetic activity to the heart. Notably, female spontaneously hypertensive rats (SHR) also have increased cardiac sympathetic nerve activity (SNA). Since elevated levels of cardiac SNA increase the risk for cardiac arrhythmias, we tested the hypothesis that hypertensive, paraplegic rats have an increased susceptibility to ventricular arrhythmias. To test this hypothesis, intact (n = 7) and paraplegic hypertensive rats (n = 6) were chronically instrumented with silver stimulating electrodes on the left ventricle, electrocardiogram (ECG) recording electrodes and an arterial catheter. After recovery, the effective refractory period, the electrical stimulation threshold to induce ventricular arrhythmias and cardiac sympathetic tonus (ST) were determined. Paraplegic rats had a lower effective refractory period (35%), lower electrical stimulation threshold to induce ventricular arrhythmias (62%), and higher cardiac ST (84%). These data document an increased susceptibility to ventricular arrhythmias in hypertensive, paraplegic rats.
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Rodenbaugh et al. (2003) studied Hypertension and paraplegia (animal model) (n=13). Paraplegia vs. Intact hypertensive rats was evaluated on Effective refractory period, electrical stimulation threshold to induce ventricular arrhythmias, and cardiac sympathetic tonus. Paraplegic hypertensive rats had a 35% lower effective refractory period, 62% lower electrical stimulation threshold to induce ventricular arrhythmias, and 84% higher cardiac sympathetic tonus.
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