Bezold Jarisch reflex

The Bezold-Jarisch reflex is a parasympathetic inhibitory reflex induced stimulation of mechanoreceptors in the heart, chemical or mechanical leading to leading to bradycardia, shallow respiration or low respiratory rate, vasodilation, and hypotension.

Bezold Jarisch reflex is thought to be the basis of some unusual reactions where hyper stimulation of the myocardium paradoxically leads to profound bradycardia or asystole.

The Bezold-Jarisch reflex is often incriminated as a cause of bradycardia or hypotension in various clinical settings such as stress testing and neuraxial anesthesia.

It has been reported to cause asystole in dobutamine induced stress testing.

The reflex is named after Albert von Bezold and Adolf Jarisch Junior.

Causes and Physiology

Prolonged upright posture results in some degree of pooling of blood in the lower extremities that can lead to diminished intracardiac volume especially in case of dehydration.

This leads to decrease in arterial pressure which is sensed by the carotid sinus baroreceptors.

Sensory fibers from these receptors trigger autonomic signals that increase cardiac rate and contractility.

However, pressure receptors in the wall and trabeculae of the underfilled left ventricle may then sense stimuli and sending signals that trigger paradoxical bradycardia and decreased contractility, resulting in additional and relatively sudden arterial hypotension.

The reflex can be seen  in following situations

• sinus bradycardia that commonly occurs within the first 60 minutes following an acute myocardial infarction
• Profound bradycardia and circulatory collapse after spinal anesthesia.
• Complication of interscalene brachial plexus block.
• The reflex occurs with several biologically active chemicals [ the chemical stimulates the arterial or ventricular baroreceptors]
  • Nicotine
  • Capsaicin
  • Veratrum alkaloids [neogermitrine and protoveratrine]
  • Bradykinin
  • Atrial natriuretic peptides
  • Prostanoids
  • Nitrovasodilators
  • Angiotensin II type 1 receptor antagonists
  • serotonin agonists may also elicit the reflex.
  • Dobutamine

Diagnosis of Bezold Jarisch Reflex

Before labeling the Bezold-Jarisch reflex as cause of bradycardia or asystole, other causes  need to be eliminated.

These are

• Inferior ischemia causing sinoatrial or atrioventricular nodal dysfunctions
• Ventricular outflow obstruction
  • Arrhythmia
  • Valvulopathies
  • Atherosclerosis or thrombi
• Ischemia caused by a dynamic obstruction

References

1. J. A. Campagna and C. Carter, “Clinical relevance of the Bezold-Jarisch reflex,” Anesthesiology, vol. 98, no. 5, pp. 1250–1260, 2003.
2.  J. B. Pollard, “Cardiac arrest during spinal anesthesia: common mechanisms and strategies for prevention,” Anesthesia & Analgesia, vol. 92, no. 1, pp. 252–256, 2001.