0854 A case of complete heart block in a patient with severe obstructive sleep apnea

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Abstract Introduction Obstructive sleep apnea (OSA) has been associated with bradycardic arrythmias and cases of transient heart block. Heart block occurring during sleep has been described in up to 10% of patients with obstructive sleep apnea, most commonly during stage R sleep and through a mechanism known as vagal activation. Stage R sleep is associated with desynchronization of respiratory and cardiovascular functions, and the excessive autonomic response (vagal activation) occurs due to the stronger stimulation of chemoreceptors and baroreceptors induced by hypoxemia, intrathoracic pressure swings, and hemodynamic alterations. Treatment of the underlying sleep-disordered breathing will typically treat the bradycardic arrythmia as well. Report of Cases: A 49-year-old male with a BMI of 30 kg/m , neck circumference of 16 inches, and obstructive sleep apnea presented to the sleep center to establish care for management of his preexisting OSA. He was previously diagnosed with moderate OSA in 2007 but had discontinued therapy shortly after due to Continuous Positive Airway Pressure (CPAP) intolerance. The patient complained of snoring, nocturia, and excessive daytime sleepiness (18/24 on Epworth Sleepiness Scale). During the split night study, the patient was noted to have 2:1 second degree heart block followed by a transient episode of complete heart block, manifested by 4 non-conducted p-waves. The patient remained asymptomatic throughout the night. Upon study completion, the patient denied any prior chest pain, presyncope, syncope, or medications that might cause heart block. Conclusion Bradyarrythmias can be seen in severe obstructive sleep apnea in the setting of excessive vagal stimulation through increased stimulation of chemoreceptors and baroreceptors. Treatment with PAP therapy can lead to prevention of heart block in 80-90% of these patients. Support (If Any)