Dr.S.Venkatesan MD

Heart by development  originates from near  the same spot , where the brain develop (Neuralcrest) .Hence there is no surprise  to note,  heart being a primary  vascular organ still retain many neural connections with brain .Eyeballs with it’s  extensive neural inputs  can be considered as adirect extension of brain.

Oculo cardiac reflex .

When the eyeballs or the ocular muscles are manipulated or massaged slowing of heart rate can occur .This is due to  a reflex called  Oculo cardiac reflex mediated by  vagal stimulation .This phenomenon is also referred to as  Aschner phenomenon

The circuit

• Afferent _Trigeminal branch of opthalmic nerve
• Center- Medulla : Trigeminal  neural signal  spill over signals  to Vagal nucleus
• Efferent- Vagus -SA node

Biochemical mediator -Acetyl choline

Prevention

• Adequate local anesthesia
• Retro bulbar block of ciliary ganglion
• Prompt Atropine injection

Courtesy :Indian journal of Ophthalmology

Clinical scenarios

1. Opthalmic surgery : Serious bradycardia  even  asystole can occur as a rare complication especially in elderly and very young (Cataract /Squint surgery) .
2. Cardiac events and  strokes  are clustered around opthalmic surgery in many elderly  for some unknown reason ( OCR triggered ?)
3. OCR can unmask hidden sinus node dysfunction in elderly.Routine cardiac evaluation before eye surgery may be recommended .
4. Orbital fracture especially Medial orbit can elicit dangerous bradycardia (BMJ Case Rep. 2014 Apr 15;2014.)
5. Rarely sudden death has been reported (Smith R (1994). “Death and the occulocardiac reflex.”. Can J Anaesth 41 (8): 760. )
6. OCR for termination of SVT/AVNRT : , One can use the eyeballs  to stimulate the brain stem nucleus of vagus to terminate a rapid supraventricular tachycardia (Like carotid sinus message) .Cold water immersion of eye is effective way to stimulate the vagus.(Diving  reflex -Mathews 1981)

Neural control of heart how Important it is ?

Many sudden cardiac deaths are now believed to be neurogenic in origin . Though,  somatic nerve  supply of heart is least important except over pericardium , extensive sympathetic and parasympathetic nerve supply is present . They can  now be visualized by  adrenergic receptor imaging  . Neuro cardiology is distinct developing field. A hyperbole:  Of course  one could argue , these connection has less overall significance as a person can live with an entirely new donor heart with zero neural connection with brain.

Reference

1.Lang S, Lanigan D, van der Wal M (1991). “Trigeminocardiac reflexes: maxillary and mandibular variants of the occulocardiac reflex.”. Can J Anaesth 38 (6): 757–60

2.Mathew PK (January 1981). “Diving reflex. Another method of treating paroxysmal supraventricular tachycardia”. Arch. Intern. Med. 141 (1): 22–3.

3.Borumandi F¹, Rippel C, Gaggl A.BMJ Case Rep. 2014 Apr 15;2014.Orbital trauma and its impact on the heart.