Vagal manoeuvres involve the stimulation of the vagus nerve that runs from the belly to the brain. It is a main part of the autonomic nervous system (ANS), which is linked with body functions including those of the heart, the lung and even the gut.
The ANS is divided into:
- the sympathetic nervous system (SNS), which is responsible for impulsive (fight or flight mode) reactions, and
- the parasympathetic nervous system (PSNS), which is all about responding in a calm and sober (rest and digest mode) manner.
Dr Guruprasad, cardiac electrophysiologist, Fortis Hospital, Vadapalani, Chennai, says that the vagus nerve is one of the main components of the PSNS. Vagal manoeuvres are often used by paramedics and health-care providers to stimulate the vagus nerve and regulate the heart rate in people with tachycardia (high heart rate). Experts advise a bit of caution as excess vagal nerve stimulation could also result in dangerously low heart rate in some people.
How do vagal manoeuvres work?
The stimulation of the vagus nerve alters the electrical conduction through the atrioventricular node of the heart which is responsible for synchronised heartbeat. The stimulated vagal nerve ensures that the pace and frequency of electrical impulse in the heart is slowed down (leading to a slower heart rate).
Common vagal manoeuvres
1. Valsalva manoeuvres: Take a deep breath and then exhale after closing the nostrils and mouth. These manoeuvres can also be done by lying down and exhaling hard in the same manner — like women in labour do to push out the baby.
“This generates increased pressure within the chest cavity and stimulates the vagus nerve, which results in a slower heart rate”, says Dr A Ravikant, senior cardiologist, Kamineni Hospitals, Hyderabad.
The valsalva manoeuvre leads to an increase in the pressure in the chest cavity. This leads to fluctuations in blood pressure, finally resulting in the simulation of the vagus nerve. Though generally considered to be safe, it is always recommended to get your doctor to explain the process to you initially and only then try it by yourself (if required).
2. Carotid sinus massage: Applying pressure to the carotid artery on the side of your neck can also stimulate the vagus nerve and help slow the heartbeat along with lowering blood pressure, says Dr Guruprasad.
“Carotid sinus massage should not be done or performed on older people as they could be having carotid artery disease,” he adds.
The carotid sinus has arterial baroreceptors which relay signals corresponding to blood-pressure variations to the ANS during the massage, which leads to the simulation of the vagal nerve.
“One should not perform a carotid sinus massage on both sides of the neck at the same time — but it can be done alternatively,” Dr Guruprasad says. “Doing massage on both sides simultaneously can lead to a very low heartbeat (or bradycardia).”
Carotid sinus message should always be performed by health-care experts.
3. Diving reflex or immersing head in ice water bucket: Doctors often advice people with severe palpitations to take a deep breath, hold it and then immerse their head in a bucket of ice water. This helps in lowering the heart rate. This method is also called the mammalian diving reflex which is common to most mammals. Cold water increases vagal nerve activity (vagal tone) and induces bradycardia (lowers heart rate). This method is often used to address supraventricular tachycardia in clinical settings. “Throwing ice water on the face can stimulate the vagus nerve,” Dr Guruprasad says.
4. Gag reflex: “The easiest way to trigger a gag reflex is by sticking your fingers inside the throat,” says Dr Vanita Arora, senior consultant electrophysiologist & interventional cardiologist, Indraprastha Apollo Hospitals, Delhi.
Dr Guruprasad says that applying or performing the gag reflex properly can also stimulate the vagus nerve, which further slows the heart rate. The gagging reflex — one of the most important reflex actions in the human body — emits nerve signals right up to medulla oblongata and also activates the vagal nerves. Some studies indicate that gagging reflex could both increase and decrease the heart rate in some people.
Risks or complications
While vagal manoeuvres can be effective in managing certain cardiac conditions, there are some risks involved.
“Vagal manoeuvres can cause a sudden drop in blood pressure that can lead to fainting,” says Dr Ravikant. He also adds that carotid sinus massage can increase the risk of stroke in people who have underlying vascular and cardiac complications.
Dr Arora says carotid sinus massage should be done under medical supervision. People should not perform vagal manoeuvres unless they have a faster heartbeat or supraventricular tachycardia. People with chest pain or low blood pressure should also avoid doing vagal manoeuvres, she adds.
Takeaways
Vagal manoeuvres are generally safe but should be done properly. People with certain medical conditions — such as carotid artery disease — should avoid carotid sinus massage, as it can cause a dangerous drop in blood pressure. It is important that people with heart disease or other medical conditions try this only after consulting medical experts.
