From the Guidelines
The Bezold-Jarisch reflex is a reflex that occurs in response to certain stimuli, including ischemia or reperfusion, resulting in decreases in heart rate, systemic vascular resistance, and blood pressure mediated by parasympathetic activity. This reflex can be triggered by various factors, including ischemia, reperfusion, or certain medications, and is characterized by sudden bradycardia, vasodilation, and hypotension 1. The Bezold-Jarisch reflex is mentioned in the context of acute myocardial infarction, where it may be related to ischemia, reperfusion, or morphine or nitroglycerin therapy 1.
Some key points about the Bezold-Jarisch reflex include:
- It is a protective mechanism that can sometimes be detrimental in clinical settings
- It can be triggered by mechanical or chemical stimuli, including hypovolemia, certain medications, or inferior wall myocardial infarctions
- Management typically involves restoring blood volume and counteracting bradycardia with medications such as atropine
- Atropine is most effective for sinus bradycardia occurring within 6 hours of onset of symptoms of acute MI, and should be used with caution due to its potential to counteract the protective effect of parasympathetic tone against ventricular fibrillation and myocardial infarct extension 1.
In clinical practice, the Bezold-Jarisch reflex can manifest as sudden fainting or near-fainting episodes, especially when a person stands up quickly while dehydrated or after prolonged standing. Atropine can be used to treat symptomatic sinus bradycardia related to the Bezold-Jarisch reflex, with doses in increments of 0.5 mg, titrated to achieve minimally effective heart rate up to a maximum of 2.0 mg 1.
From the Research
Definition and Characteristics of the Bezold-Jarisch Reflex
- The Bezold-Jarisch reflex (BJR) is an inhibitory reflex characterized by bradycardia, hypotension, and apnea originating from ventricular mechanoreceptors 2.
- It is a cardioinhibitory parasympathetic response to activation of ventricular mechanoreceptors, which can result in bradycardia, atrioventricular block, or asystole 3.
- The reflex is a depressor reflex of the heart due to the preferential distribution of vagal nerves in the inferior wall of the left ventricle 4.
Triggers and Associations
- BJR can be triggered by acute myocardial ischemia, intra-arterial nitroglycerine use, natriuretic peptides, and dobutamine infusion during stress echocardiography 3.
- It may occur during regional anesthesia, upper-extremity blocks, and sometimes in general anesthesia, resulting in hypotension, bradycardia, apnea, or cardiac arrest elicited by chemical or mechanical receptor stimulations 5.
- The reflex can also be caused by severe dystrophic cervical kyphotic deformity leading to thoracic inlet compression 6.
- Coronary spastic angina can cause the Bezold-Jarisch reflex in the acute phase of Stanford type A acute aortic dissection 4.
Clinical Presentation and Management
- The clinical presentation of BJR includes bradycardia, hypotension, apnea, or cardiac arrest 2, 5.
- Management of BJR involves stopping anesthesia, intravenous fluid, left-lateral positioning, judicious vasopressors, fetal monitoring, and preparing for emergent delivery in cases of neuraxial anesthesia 2.
- In cases of severe cervicothoracic deformities, thoracic inlet decompression may be necessary to address the unique complication of BJR 6.
- Recognition of the Bezold-Jarisch reflex is crucial, as it may require different management than other conditions 4.