Abstract
Numerous unusual causes of atrioventricular block (AVB) with cardiac pacemaker implantation have been documented including cough, deglutition, or other vagally mediated mechanism. In spinal cord lesions, only high cervical spinal cord lesion has been reported as a cause of severe bradycardia. We report a case with not cervical but dorsal vertebral trauma and persistent paroxysmal AVB requiring cardiac pacemaker implantation.
Case report
A 46-year-old man was referred to the trauma centre of our University Hospital following a motorcycle accident in which he suffered high dorsal direct trauma. Initial neurological examination found complete loss of voluntary motor and conscious sensory functions below the second dorsal cord. Vertebral computerized tomography (CT) scan revealed focal and stable D2 fracture. Since post-injury Day 6, he developed several episodes of prolonged asystole, consecutive to paroxysmal third-degree atrioventricular block (AVB). A temporary VVI 60 bpm pacemaker was placed on Day 10, following failure of prevention using repeated atropine and isoproterenol administrations.
Holter ECG tracing (Figure 1) was recorded while temporary cardiac pacemaker was temporary turned off. The analysis of the recorded episode showed progressive decrease in sinus rhythm rate followed by complete AVB with few junctional escape beats, then prolonged asystole. Cardiac resuscitation was started after 25 s of asystole. At 60 s, cardiac pacemaker VVI 80 bpm was turned on. Two minutes after the beginning of the episode, sinus rhythm resumed at 90 bpm.
(A) Holter ECG tracing showing prolonged asystole requiring cardiac resuscitation. Temporary cardiac pacemaker VVI 80 bpm was turned on after 60 s and sinus rhythm resumed after 120 s. No precipating factors such as proprioceptive or visceral stimulus was found. (B) Complete atrioventricular block with junctional escape beats followed by prolonged asystole in the absence of longer escape rhythm. Associated sinus bradycardia is in favour of a vagally mediated mechanism.
The persistence of asystole events on Day 42 required permanent ventricular pacemaker implantation. Thereafter the patient remained asymptomatic.
Discussion
Bradycardia is a common complication of acute cervical spinal cord injury (SCI) occurring in up to 100% of these patients.1 Asystole is not rare reported in as many as 15% of these patients within first 5–6 weeks after the SCI.1 The primary mechanism of these bradyarrhythmias appears to be an imbalance between a vaso-vagal reflex and the injured cardiac sympathetic nerve located in the cervical spinal cord.1
At this moment, precipating factors such as tracheal suction or hypoxemia are generally found, and manoeuvres aimed at avoiding precipitants are the first step of the treatment of bradycardia in spinal cord-injured patients. Administration of atropine or isoproterenol has been also empirically recommended.
Several cases of patients with high cervical SCI and symptomatic drug-resistant bradyarrhytmias still occurring after the phase of spinal shock requiring permanent pacemaker implantation have been reported.2
To the best of our knowledge, no previous permanent pacemaker therapy has been described for recurrent asystole in a patient with dorsal SCI. In the present case, the mechanism of recurrent asystole remains not well established. Spinal magnetic resonance imaging (MRI) might have brought further information. Unfortunately, it was not performed before pacemaker implantation.
The preganglionic sympathetic innervations to the heart exit the spinal cord at level D1 through D4. A damage of these structures at the level of the main lesion can be speculated. Late recurrence of near fatal asystole 6 weeks after the SCI was the indication of a permanent cardiac pacemaker implantation in our case. Now available MRI-compatible cardiac pacemaker should be considered in such conditions.
Conclusion
Recurrent asystole complicating a SCI are secondary to high cervical lesion leading to an imbalance in the autonomic nervous system. We report the rare case of a patient suffering from a D2 SCI who presented several cardiac arrests by third-degree AVB requiring permanent pacemaker implantation 6 weeks after injury.
Conflict of interest: none declared.
