Anesthetic Considerations for Cesarean Delivery in a Patient With Third-Degree Heart Block: A Case Report

Congenital third-degree complete heart block (CHB) detected during pregnancy is a rare condition. This report discusses a pregnant patient with an incidental finding of CHB and its implications for maternal and fetal outcomes. A 21-year-old female patient, gravida 2 para 0 (G2P0010), first registered at five weeks, two days gestation, with an incidental finding of third-degree heart block. Her baseline heart rate of 40-50 beats per minute, with no prior cardiac diagnosis. She had a history of miscarriage at six weeks' gestation. During the current pregnancy, she experienced two episodes of dizziness upon standing, each resolving within a minute without signs of hemodynamic instability. A 12-lead EKG and 24-hour Holter monitoring confirmed CHB, and echocardiography ruled out secondary causes. Cardiology and electrophysiology recommended temporary transcutaneous pacing and bedside atropine in case of instability. CHB in pregnancy is often congenital and characterized by independent ventricular activity due to atrial stimulus blockage. While typically asymptomatic, symptoms such as dizziness, hypotension, syncope, severe bradycardia, and cardiac arrest can occur. Pregnancy and labor stress, including the Valsalva maneuver, can exacerbate bradyarrhythmia, leading to adverse outcomes. Inadequate fetal perfusion and oxygenation can result in fetal bradycardia and hypoxia. Management requires a multidisciplinary approach, with echocardiograms, Holter monitoring, and, in some cases, cardiac MRI to rule out structural heart disease. Asymptomatic patients with good functional capacity may avoid permanent pacemakers, though temporary pacing is considered on a case-by-case basis. Neuraxial anesthesia is preferred for cesarean delivery in both symptomatic and asymptomatic CHB patients due to its minimal impact on myocardial function. General anesthesia should be avoided when possible. If necessary, anesthetic agents with minimal cardiac depression, such as ketamine, etomidate, rocuronium, and isoflurane, are recommended. Assisted early deliveries, such as vacuum or forceps, can help reduce the risk of Valsalva-induced bradycardia. Asymptomatic CHB cases without significant heart disease typically have favorable outcomes. However, careful cardiovascular monitoring and individualized care plans are essential to mitigate potential complications. Postpartum cardiology follow-up is necessary to assess the development of new symptoms and determine the need for a permanent pacemaker. This case highlights the importance of early diagnosis, adequate monitoring, early elective delivery, and multidisciplinary management in CHB during pregnancy. Neuraxial anesthesia and strategic labor management are key to ensuring positive maternal and fetal outcomes. Further research is needed to develop standardized guidelines for this rare condition.