Vasovagal response characterized by slow Heart rate, sudden drops in Blood Pressure and Fainting. It is due to response of the vagus nerve. It can be dangerous sometimes and require treatment. More than 50% of syncope in the world is due to a vasovagal response.

Cause/Etiology of Vasovagal Response

It induced by triggers, Triggers may vary from person to person.

  1. The sight of blood, Neddle, unpleasant things or be in a unpleasant situation.
  2. Pain
  3. Stress
  4. Standing for a long period.

Pathophysiology of Vasovagal Response

In response to the above triggers, vagus nerve stimulated and it activates parasympathetic response(Vagal tone) and withdraws Sympathetic response tone. It affects the Sinoatrial node(SA Node) of the heart causes bradycardia(Decrease heart rate) and decrease heart contractibility. Which leads to decrease cardiac output and it ultimately leads to severe hypotension(Dropping blood pressure).

Withdrawl of Sympathetic response causes loss of muscle tone so, it widens blood vessels(Vasodilation). Decreased cardiac output and vasodilation make the condition worse and dramatically decrease blood flow to the brain. It causes fainting which is known as vasovagal syncope, it is also known as neurocardiogenic syncope.

Vasovagal in Cath Lab

During coronary angiography, renal angiography and carotid angiography the arterial access is needed. The vasovagal response is common in femoral artery access or during removal of the arterial sheath. It’s mainly due to severe pain, fear of blood loss or fear of harm. It can be avoided by administering local anesthesia in the access site. Heath education and diversional therapy are very important during arterial access to reduce vasovagal response.

During arterial access or sheath removal, closely monitor the vitals of the patient, keep talking with the patient and ask for any discomfort. For safe side always keep atropin injection and normal saline ready.

Signs and symptoms of Vasovagal response

Before syncope you may feel lightheadedness, Dizziness, blurred vision and slow weak pulse, but it’s very difficult to recognize. Vasovagal syncope is resolved normally by the body in most cases. In rare cases, it may lead to seizure and organ damage due to prolonged hypotension.

Treatment of vasovagal response

If you can identify pre symptoms or feel like faint then lie down in-ground and elevate your leg to increase blood supply to the brain. Vasovagal normally reverted by Injection atropin and intravenous fluid bolus. The best way of prevention is to avoid the triggers.

Elevate your leg to increase blood flow to the brain

Complication of vasovagal response

Complications include fall-related injuries and multi-organ failure in prolonged hypotension.

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Biswa Prakash

Hi, I am Biswa Prakash Swain, a Public Health expert and author of this Article. I have Done BSc in Nursing and Masters in Public Health (Epidemiology), Now Preparing for Ph.D. in Epidemiology and Clinical Research. I have more than 7 years of experience in Healthcare sectors like Hospitals and almost 4 years of experience in the Public health field and Clinical research.


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