Sinus node dysfunction in spinal cord injury with quadriplegia

Abstract

Patients with recent spinal cord injury and quadriplegia often demonstrate sinus bradycardia (SB), sinus arrest (SA), AV block, and hypersensitivity to vagotonic maneuvers. The presumed mechanism is interruption of the sympathetic nerves to the heart, with a relative increase in parasympathetic tone. To determine the need for permanent pacing, we examined seven patients with recent spinal cord injury and quadriplegia prospectively, 1 to 2 weeks after injury. All patients had transient SB (35-60) and SA (2-8 set). These episodes often occurred with nasotracheal suctioning, despite prior treatment with atropine and hyperventilation. In 5 of 7 patients, His-Bundle Ek!CtFogramS and sinus node recovery times (SNRT)were determined and found to be normal (A-~=10&20 msec, H-V=443 msec, SNRT=llO??lO% of resting cycle length). In 4 of 5 patients there was no disturbance in sinus node function with carotid sinus pressure, during nasotracheal suctioning or with hypoxemia. One patient had SA (4-6 set) with carotid sinus pressure and during suctioning. 6 of 7 patients had later episodes of SA and SB requiring permanent pacemakers. We conclude that there is marked temporal variability in sinus node dysfunction in patients with recent spinal cord injury and quadriplegia. A normal response to sinus node testing does not assure continued normal function. We, therefore, recommend permanent pacemaker insertion in patients with recent spinal cord injury with quadriplegia who have had significant SA or SB.