From the Guidelines
Bradycardia in subarachnoid hemorrhage is a serious complication that requires prompt recognition and management, often representing a manifestation of Cushing's reflex, which is a physiological response to increased intracranial pressure. When bradycardia occurs in SAH, treatment typically involves addressing the underlying SAH while managing the bradycardia. For symptomatic bradycardia, atropine 0.5-1 mg IV can be administered, which may need to be repeated every 3-5 minutes up to a maximum of 3 mg, as suggested by general medical guidelines 1. In refractory cases, temporary cardiac pacing might be necessary. Continuous cardiac monitoring is essential, and blood pressure management is crucial, often requiring a balance between preventing hypertension (which can worsen bleeding) and maintaining cerebral perfusion pressure.
The bradycardia in SAH is often due to activation of the parasympathetic nervous system as the brain attempts to reduce blood flow in response to rising intracranial pressure. This mechanism explains why bradycardia, along with hypertension and irregular breathing (Cushing's triad), can signal deteriorating neurological status and requires immediate neurosurgical evaluation for possible intervention to reduce intracranial pressure. The most recent guidelines for the management of patients with aneurysmal subarachnoid hemorrhage, published in 2023, provide recommendations based on current evidence for the treatment of these patients, emphasizing the importance of evidence-based approaches to improve quality of care 1.
Key considerations in managing bradycardia in SAH include:
- Prompt recognition of bradycardia as a potential complication of SAH
- Addressing the underlying cause of SAH while managing bradycardia
- Use of atropine for symptomatic bradycardia
- Continuous cardiac monitoring and careful blood pressure management
- Consideration of temporary cardiac pacing in refractory cases
- Immediate neurosurgical evaluation for signs of deteriorating neurological status.
From the Research
Relationship Between Bradycardia and Subarachnoid Hemorrhage
- Bradycardia, or an abnormally slow heart rate, has been observed in patients with subarachnoid hemorrhage (SAH) in several studies 2, 3.
- A cross-sectional study published in 2023 found that 24.4% of patients with non-traumatic SAH had bradycardia, which was one of the most common electrocardiographic (ECG) abnormalities associated with SAH 2.
- Another study published in 2018 found that sinus bradycardia was more common in patients with traumatic SAH, occurring in 31.4% of patients, compared to those with spontaneous SAH 3.
- The exact mechanism of bradycardia in SAH is not fully understood, but it is thought to be related to the neural-mediated process rather than a manifestation of coronary artery disease 3, 4.
- Cardiac complications, including bradycardia, have been associated with increased morbidity and mortality in patients with SAH, and early treatment of cerebral injury may help reduce the incidence of cardiac complications 3, 4, 5, 6.
Prevalence of Bradycardia in SAH Patients
- The prevalence of bradycardia in SAH patients varies depending on the study, but it is generally reported to be around 20-30% 2, 3.
- A study published in 2022 found that SAH patients have a high risk of developing cardiac syndromes, including takotsubo syndrome, which can present with similar symptoms to bradycardia 6.
- The underlying pathophysiology of cardiac syndromes in SAH is complex and involves the interplay of neural and cardiac factors, leading to a variety of cardiac complications, including bradycardia 6.
Clinical Implications
- The presence of bradycardia in SAH patients may impact morbidity and mortality, and early recognition and treatment of cardiac complications are essential to improve patient outcomes 4, 5, 6.
- Further studies are needed to evaluate the significance of ECG changes, including bradycardia, and their correlation with clinical outcomes in SAH patients 2, 3, 4.