MANAGEMENT OF RECURRENT BRADYCARDIA WITH THEOPHYLLINE IN THE SETTING OF SPINAL CORD INJURY

Abstract

TOPIC: Cardiovascular Disease TYPE: Medical Student/Resident Case Reports INTRODUCTION: Cardiovascular complications are common in patients with cervical or high thoracic spinal cord injury (SCI) including autonomic dysreflexia and cardiac arrhythmias. Cardiac instability is a result of disruption of the descending sympathetic pathways and lack of compensation to parasympathetic responses via the vagus nerve for supraspinal control of the heart. We present a rare case of a 49-year-old male with recurrent episodes of bradycardia and subsequent complete heart block post SCI responding to theophylline. CASE PRESENTATION: 49-year-old male with a history significant for T5 fracture and spinal cord injury resulting in paraplegia was found to have brief episodes of bradycardia two months post accident during prolonged ventilator weaning. He was initially treated with and titrated off chronotropic agents (dopamine and isoproterenol). A month later, he began having recurrent episodes of transient complete heart block with the absence of ventricular activity for up to 30 seconds. After the period of heart block, he would progress to sinus bradycardia for about 30 seconds before transitioning to normal sinus rhythm. After specialty consultation, the patient was started on theophylline 100 mg three times daily with complete resolution of his symptoms for nine days. Then, during manual disimpaction, he had re-emergence of his transient complete heart block and had a brief cardiac arrest with pulseless electrical activity, which led to the implantation of a leadless pacemaker. DISCUSSION: This patient is unique in that cardiac dysrhythmias and cardiac arrest are more common in the acute phase of SCIs (2-6 weeks post injury), whereas this patient was 3 months post injury. Chronotropic and inotropic infusions are the primary treatment strategy for bradyarrhythmias. Dopamine and isoproterenol were trialed in the patient but stopped due to transient improvement in the symptoms. Minimizing vagal stimulation is important for the prevention of bradycardia associated with SCIs. Theophylline has been found to have anti-bradyarrhythmia effects and may be used for prevention of recurrent bradycardia. The mechanism is thought to be through antagonism of adenosine receptors, which is a crucial pathway in patients with high SCIs with unopposed vagal tone. In this case, initiation of oral theophylline prevented recurrent bradycardia and complete heart block for 9 days before a pacemaker was implanted. CONCLUSIONS: Routine use of theophylline to prevent cardiovascular complications in spinal cord injuries is not well known. Methylxanthine therapy may prevent recurrent bradyarrhythmias from occurring and avert or delay implantation of a pacemaker. REFERENCE #1: Furlan JC, Fehlings MG. Cardiovascular complications after acute spinal cord injury: pathophysiology, diagnosis, and management. Neurosurg Focus. 2008;25(5):E13. doi: 10.3171/FOC.2008.25.11.E13. REFERENCE #2: Alboni P, Rossi P, Ratto B, Pedroni P, Gatto E, Antonioli GE. Electrophysiologic effects of oral theophylline in sinus bradycardia. Am J Cardiol.1990; 65:1037-1039. REFERENCE #3: Whitman CB, Schroeder WS, Ploch PJ, Raghavendran K. Efficacy of aminophylline for treatment of recurrent symptomatic bradycardia after spinal cord injury. Pharmacotherapy. 2008 Jan;28(1):131-5. doi: 10.1592/phco.28.1.131. DISCLOSURES: No relevant relationships by Kirsten McGrew, source=Web Response No relevant relationships by Lindsay Saum, source=Web Response No relevant relationships by Adam Smalley, source=Web Response