Vagal Maneuvers: How to Stop your Patient’s SVT

Vagal Maneuvers: How to Stop your Patient’s SVT

William J. Kelly, MSN, FNP-C
William J. Kelly, MSN, FNP-C

Author | Nurse Practitioner

Vagal maneuvers are used in the clinical setting to slow down fast heart rates – primarily for supraventricular tachycardia (SVT)  and sometimes rapid atrial fibrillation (AF RVR).

There are numerous physical maneuvers that can slow down the heart rate – and there is an important modified technique which can almost triple your chances of success!

Vagal maneuvers for SVT fbook image

Svt and Vagal Maneuvers

Supraventricular Tachycardia (SVT) is a very rapid regularly arrhythmia caused by a reentrant loop within the heart.

Essentially – the signal goes around and around in a circuit, producing very fast heart rates.

reentrant loop gif

While SVT is an umbrella term for any tachycardia originating above the ventricles of the heart, it usually is used in reference to AV Nodal Reentrant Tachycardia (AVNRT). This arrhythmia is due to a reentrant loop within/near the AV node itself.

Some patients have abnormal conduction tissue in this area, and if a premature beat comes at the wrong time – it can throw them into this very fast heart rhythm.

This condition occurs more often in younger patients, females, and can be secondary to certain triggers like exercise, stimulants, or even alcohol.

Patients will usually be symptomatic and feel palpitations, fatigue, or dizziness. They can also have chest pain, SOB, or syncope.

Remember when the heart is beating this fast, the cardiac chamber’s ability to fill is decreased, and cardiac output can suffer – leading to symptoms.

When a patient comes in with SVT, their heart rate is usually very fast, with rates often between 150-200 bpm.

AVNRT-svt

We want to stop or “break” this rhythm as soon as possible, so the patient does not decompensate.

If we look at the Adult tachycardia ACLS algorithm, we can see that the first thing we do to attempt to stop the SVT in a stable patient is vagal maneuvers.

The Vagus nerve and the Heart

In order to understand vagal maneuvers, you first need to understand how the vagus nerve works.

The vagus nerve is the primary method that the parasympathetic nervous system affects the body.

This is the 10th cranial nerve which travels from your brain throughout the body. This is how the brain controls certain automatic functions.

When the vagus nerve is activated, the following effects on the body occur:

  • Bronchial constriction
  • Pupillary constriction
  • Increased blood flow to the stomach’
  • Increased digestion

Remember – “rest and digest”

Regarding the heart, the vagus nerve also has important physiological effects on the cardiac system. These include:

  • Slowing of the heart rate
  • Slowing of the conduction velocity of the AV node
  • Decreases the strength of contractions

As you can see, stimulation of the vagal nerve can be utilized to slow the conduction and increase the refractory period of the AV node which hopefully breaks the SVT reentrant loop, leading to conversion back to normal sinus rhythm (NSR).

There are various physical maneuvers that can stimulate the vagus nerve – and many you may do without trying. These include:

  • Coughing
  • Vomiting
  • Cold water immersion

Then there are certain physical maneuvers termed “vagal maneuvers” that we can perform in the hospital to intentionally cause vagal response and hopefully slow down a tachyarrhythmia such as with SVT.

These maneuvers include the Valsalva maneuver and the carotid sinus massage.

But did you know that by modifying the Valsalva maneuver – you can almost triple your chances of success?

The Modified Valsalva Maneuver

The Valsalva maneuver is the classic vagal maneuver used to stimulate the vagus nerve and stop SVT.

This is used on patients who are stable (stable vital signs) and can follow commands.

To perform the Valsalva maneuver, the patient intentionally “bears down” or strains for 10-15 seconds.

This has a 17% success rate in converting SVT. However, by modifying the Valsalva maneuver we can almost triple this success rate!

The Modified valsalva or the positional valsalva maneuver has a significantly higher success rate of 43%!

That’s almost half of your patients with SVT who this can convert back to NSR without any additional medications or interventions.

To perform the modified Valsalva maneuver:

  1. Have a Physician or APP at the bedside
  2. Place the patient in a semi-recumbent position (45° Semi-fowlers)
  3. Have the patient take a normal breath in
  4. Have them forcefully exhale with a closed glottis (bearing down) for 15 seconds
  5. Immediately place them supine and raise their legs to 45 degrees for 15 seconds
  6. Return to semi-fowlers position and watch for up to 1 minute for resolution of the SVT

Clinical Tip: If the patient has trouble bearing down, you can place an empty 10-mL syringe in their mouth and have them blow hard enough to see the plunger move.

As you can see, this technique requires a few assistants, but it is clearly the better option when attempting to convert SVT with vagal maneuvers.

The modified valsalva maneuver infographic

The Carotid Sinus Massage

The carotid sinus massage is a vagal maneuver that you can perform on someone who cannot follow commands.

The carotid sinus is an area located just below the internal carotid artery at the level of the thyroid cartilage, near the pulse.

This area is very sensitive to mechanical pressure, and mechanical pressure to this area can stimulate the vagus nerve.

To perform the carotid sinus massage:

  1. Place the patient supine with their neck extended toward the opposite side
  2. Ensure there is no carotid bruit with your stethoscope
  3. Locate the carotid sinus. This is inferior to the angle of the mandible at the level of the thyroid cartilage near the pulse
  4. Apply firm pressure for 5-10 seconds
  5. You can repeat on the other side if needed

The carotid sinus should never be performed in the following circumstances:

  • Without a physician / APP at the bedside
  • On both sides simultaneously
  • In someone with TIA or stroke within the last 3 months
  • In someone with known carotid stenosis or active carotid bruit

Carotid sinus massage infographic

Complications of Vagal Maneuvers

Any side effects from vagal maneuvers are usually short-lived and an “over-exaggeration” of expected effects.

These include sinus pauses, brief asystole, bradycardia, AV blocks and hypotension.

These will usually fix themselves within seconds to minutes.

Strokes are a major concern with the carotid sinus massage and can happen in <1% of patients.

This is why those with potential carotid stenosis or recent history of strokes should not have the carotid sinus massage.

References:

Aehlert, B. J. (2017). ECGs made easy (6th ed.). Elsevier Health Sciences.

Burns, E. (2019). Supraventricular tachycardia. In ECG Library. Retrieved from https://litfl.com/supraventricular-tachycardia-svt-ecg-library/

Frisch, D. R., Zimetbaum, P. J. (2020). Vagal maneuvers. In UpToDate. Retrieved from https://www.uptodate.com/contents/vagal-maneuvers

Grauer, K., MD. (2014). ECG Pocket Brain: Expanded Version (6th ed., pp. 65-68). Gainesville, FL: KG/EKG Press.

Knight, B. P. (2020). Atrioventricular nodal reentrant tachycardia. In UpToDate. Retrieved from https://www.uptodate.com/contents/atrioventricular-nodal-reentrant-tachycardia

Tintinalli, J. E., Brady, W. J., Laughrey, T. S., & Ghaemmaghami, C. A. (2016). Cardiac Rhythm Disturbances. In Tintinalli’s emergency medicine: A comprehensive study guide (8th ed., pp. 126). McGraw-Hill Education.

Want to Learn More?

If you want to learn more about vagal maneuvers, SVT, and every other cardiac arrhythmia – check out my ECG Rhythm online video course out now!

It’s specifically designed for nurses, and not only teaches you how to identify each arrhythmia, but also why and how they occur, and what to do about it!

If you’re not ready to take that leap yet but still want to learn more about ECG rhythms – be sure to download my free ECG Cheat Sheet below!

You may also like:

Vagal maneuvers for SVT Pin

The Cranial Nerve Assessment for Nurses

The Cranial Nerve Assessment for Nurses

The cranial nerve assessment is an important part of the neurologic exam, as cranial nerves can often correlate with serious neurologic pathology. This is important for nurses, nurse practitioners, and other medical professionals to know how to test cranial nerves and what cranial nerve assessment abnormalities may indicate. This becomes especially important when evaluating potential new strokes.

In school, cranial nerves tend to be something you memorize and then forget the day after the test. But they are important in testing a patient’s neurologic status, as an abnormality in a cranial nerve can indicate a central lesion (stroke, tumor, bleed, etc).

Every nurse should at the least know how to do a basic cranial nerve assessment, specifically the visual acuity and pupillary light reflex. When evaluating a stroke, The NIH scale is a method to evaluate the severity of a stroke. This scale walks you through evaluating many of the cranial nerves, but not all of them. If you want to feel confident when you chart “Cranial nerves II-XII grossly intact”, then keep reading!

1. The Olfactory Nerve (CNI)

The olfactory nerve is responsible for the sense of smell. Although rarely tested in practice, alterations in smell can be caused by serious intracranial pathology (brain tumors, strokes, TBI), neurodegenerative diseases like Alzheimer’s, Parkinson’s, or MS, or benign and transient causes such as the common cold.

If both branches of the olfactory nerve are damaged, this can lead to permanent anosmia (loss of smell) and can lead to food tasting bland and decreased appetite. In most individuals, the sense of smell decreases over time, with up to 75% of individuals older than 80 have some degree of anosmia.

 How to test the Olfactory Nerve

The olfactory nerve is almost never tested within an acute care setting such as in the hospital. However, this is sometimes tested in outpatient neurology offices. To test the olfactory nerve, blindfold the patient and have them smell and identify common scents such as vanilla, cinnamon, coffee, or peppermint while covering up one nostril at a time. Do not use ammonia or alcohol as these can trigger intranasal trigeminal nerve receptors and bypass the olfactory nerve.

2. The Optic Nerve (CNII)

The optic nerve is the second of the cranial nerves and is responsible for vision. This nerve transmits signals perceived in the retina and cones of the retina to the occipital lobe. This is commonly tested within the clinical setting and for a variety of presentations.

Partial or complete loss of vision can be caused by conditions such as:

  • Diabetes
  • Intracranial pathology (ischemia, stroke, tumors)
  • Inflammation or infection of the eye
  • Toxicity

How to test the Optic Nerve

When testing the optic nerve, you need to examine the visual fields, the visual acuity, and the pupillary light reflex. All three are an important part of the cranial nerve assessment, although the pupillary light reflex involves cranial nerve 3 as well.

Testing the Visual Fields (II)

If the patient loses part of their vision on one side, it is termed partial hemianopia, and if they lose complete vision on one side it is complete hemianopia. There are a few different ways to test visual fields, but here is an easy way. Stand one arm length away from the patient and ask them to cover up one eye or do it for them if they are unable. Close your own eye on the same side. Now hold up numbers with your fingers at each of the four corners of their vision. Once satisfied, test the other eye.

Testing the Visual Acuity (II)

Nurses often assess visual acuity, and most emergency departments will have a Snellen eye chart to use. The distance the patient stands depends on the visual acuity chart (it should say). If you do not have easy access to this, there is an app you can get on your phone which is super helpful!

Have the patient stand the appropriate distance away and have them cover up one eye. Do not have them forcibly close the eye as this can somewhat inhibit their ability to see out of their open eye. Ask the patient to read the 20/20 line on the chart. On a standard Snellen eye chart, this would be 20 feet away. If the patient gets more than half wrong, move onto the line above. Stop once the patient gets over 50% right. Mark this down and test the other eye. If they wear glasses – have them wear their glasses for this as well!

Pupillary Light Reflex (II, III)

The pupillary light reflex tests both cranial nerves II and III. First, inspect both pupils and make sure they are equal in size and shape. Then dim the lights if possible and shine a penlight directly into the right eye. Both pupils should constrict and maintain symmetry. Note if they are brisk or sluggish and if they are symmetric. Remove the light source and watch both eyes dilate equally as well. Do the same for the left eye.

3. The Oculomotor Nerve (CNIII)

The oculomotor nerve controls the majority of the extraocular muscles. It is primarily responsible for eye movement, eyelid movement, and pupillary constriction. If there is any oculomotor nerve impairment, there will be a pupillary dilation, ptosis (drooping eyelid), and outward deviation of the eye – termed abduction. When a patient has diplopia (double vision), it is often due to a unilateral lesion on this cranial nerve. In most cases, third nerve palsy resolves over weeks to months.

Causes of oculomotor nerve palsy include:

  • Intracranial aneurysm
  • Microvascular ischemia (in diabetics especially)
  • Trauma: Severe blows to head with skull fracture

Testing Extraocular Muscles (III, IV, VI)

To test the oculomotor nerve, you need to assess the EOMs. Testing the EOMs also tests cranial nerves IV and VI, as all three nerves are responsible for eye movement.

Hold your finger or a pen 2 feet in front of the patient’s eyes midline and have the patient focus on it with both eyes. Ask the patient to follow your finger or pen with only their eyes, moving the pen to the right, back to the midline, and then to the left and back again. Do this again for up and down. Lastly, do this again to the down-left diagonal angle, and then the down-right diagonal angle. You should have tested a total of 6 different directions – termed the “6 cardinal directions”.

Eye movement should be symmetric, smooth, and moving in all directions. At each extremity of vision, you should be observing excessive nystagmus. Nystagmus is repetitive uncontrolled eye movement.

Conjugate nerve palsy is when both eyes are unable to look in a specific direction during your testing. This most commonly occurs in the horizontal directions. This is usually due to a stroke within or near the brain stem.

The pupillary light reflex listed above is also used to assess the oculomotor nerve.

4. CN IV: The Trochlear Nerve

The fourth cranial nerve, the trochlear nerve, innervates the superior oblique muscle of the eyes. This means it controls the downward movement of the eyeball and prevents it from rolling upward. When there is a fourth nerve palsy, patients will often complain of vertical diplopia and/or tilting of objects. This may be most noticeable when in a downward gaze such as when going down the stairs. They may also have a head tilt, as the visual changes improve with tilting of the head. On exam, the eye will with deviated upward and rotated outward.

Testing the trochlear nerve involves evaluating the patient’s extra-ocular movements as described above.

5. CN V: The Trigeminal Nerve

The Trigeminal nerve is the 5th cranial nerve and responsible for facial sensation, as well as moving the muscles involved with biting and chewing. This has three branches including the ophthalmic V1, maxillary V2, and Mandibular V3. Compression of this nerve root can cause trigeminal neuralgia – a rare but painful condition.

How to test the Trigeminal Nerve

To test the trigeminal nerve, you are testing their facial sensation. Lightly touch both sides of the forehead and ask if they felt the same. Do this on the cheek, and then the chin. If the patient is uncooperative, you can test their corneal reflex. Do this by having the patient look right, then touch their left cornea with a whisp of cotton. They should blink. Do this on both sides.

6. CN VI: The Abducens Nerve

The sixth cranial nerve, the abducents nerve innervates the lateral rectus muscle of the eye. This means its responsible for outward movement of the eyes. Patients with dysfunction of this nerve will be unable to outwardly move their eyes. This causes horizontal diplopia, where the double images are side-by-side, which is worse at far distances.

This nerve is often the first nerve compressed when there is any increased intracranial pressure (ICP). However, more common causes include vascular disease (diabetes, hypertension, atherosclerosis) or trauma.

To test the abducents nerve, test the EOMs as described above.

7. CN VII: The Facial Nerve

Cranial nerve VII is the facial nerve, which controls the muscles of facial expression, as well as the sensation of taste of the front of the tongue. Facial nerve palsy can occur for various reasons, the most common being Bell’s palsy. Some other common causes include stroke, Lymes disease, trauma, or even diabetes.

How to test the Facial Nerve

To test the facial nerve, you must assess the patient’s facial expressions. Have the patient close their eyes tightly, then have them open their eyes. Ask them to frown, looking for symmetry in the forehead muscles. Have them smile and look for any drooping or asymmetry.

Clinical Tip: To differentiate Bell’s palsy from stroke, assess the patient’s use of their forehead muscles. Peripheral nerve lesions (such as with Bell’s palsy) cause paresis of the entire side of the face. Central lesions tend to only effect the lower portion of the face. This is not always the case though, so you must use clinical judgement. Bell’s palsy should have no other associated neuro deficits. Check out my Infographic for more information!

8. CN VIII: The Vestibulocochlear Nerve

The vestibulocochlear nerve, also called the auditory vestibular nerve, is responsible for hearing and balance. Vestibular neuritis is when the nerve becomes inflamed and can cause vertigo, dizziness, and balancing difficulties – most likely from a viral infection.

How to test the Vestibulocochlear Nerve

While not routinely tested within the hospital, the vestibulocochlear nerve involves testing both hearing and balance. Hearing is tested by holding your fingers a few inches away from their ears and rubbing them together. If they can hear, then that is a pass. Test their balance by assessing their gait while walking. The presence of nystagmus can also indicate vestibular dysfunction.

9. CN IX: The Glossopharyngeal Nerve

The glossopharyngeal nerve is partially responsible for the sensation of taste, pharyngeal sensation, as well as for the gag reflex. A damaged glossopharyngeal nerve can cause a loss of taste in part of the tongue and cause trouble swallowing.

How to test the Glossopharyngeal Nerve

Palatal Movement (IX, X)

Instead of doing the gag reflex which can be very uncomfortable for patients, you can instead assess palatal movement. Do this by having the patient yawn or say “ahh”, and observe their palate movement for symmetry. If this is abnormal, consider testing the gag reflex.

Gag Reflex (IX, X)

When performing the cranial nerve assessment, the easiest way to test the glossopharyngeal nerve is to test their gag reflex, however, this is usually not necessary in the clinical setting. Remember that approximately 20% of people will not have a gag reflex at baseline. Check both sides of the pharyngeal wall by gently poking the pharynx with a cotton swab.

Dysarthria (IX, X, XII)

There is no specific test for this but listen to the patient’s speech. Assess for any slurred speech or abnormality of the voice. Ask the patient or the family if it sounds different than normal.

10. CN X: The Vagus Nerve

The Vagus nerve innervates the hearts, lungs, and digestive tract, along with a few muscles. Most noticeably, it controls the heart rate, GI motility, sweating, and speech. It is also partially responsible for the gag reflex (along with cranial nerve IX).

Overstimulation of the vagal nerve can drop the heart rate and cause syncope, termed vasovagal syncope. Activities that stimulate the vagal nerve include bearing down, holding breath, carotid massage, or extreme fear or stress.

There are even implantable vagus nerve stimulators that can help slow down the firing of neurons within the brain and thus help manage seizures.

How to test the Vagus Nerve

The only real way to test the vagus nerve is via the gag reflex as described above.

11. CN XI: The Accessory Nerve

The accessory nerve innervates the sternocleidomastoid and trapezius muscles. This means it is responsible for tilting/rotating the head as well as shrugging the shoulders. This nerve can be damaged after neck surgery or blunt force trauma.

How to test the Accessory Nerve

To test the trapezius muscle, ask the patient to shrug both of their shoulders at the same time. Then apply some downward pressure with both hands and ask them to shrug both shoulders against the resistance.

To test the sternocleidomastoid, place a hand against their cheek and ask them to rotate their head against resistance in each direction. If you notice weakness, this indicates the opposite side is the weaker muscle.

12. CN XII: The Hypoglossal Nerve

The hypoglossal nerve controls most of the movement of the tongue. This means it is highly responsible for speech and swallowing. Damage to the hypoglossal nerve is rare, but if so are likely to be caused by tumors or gunshot wounds. Other causes include stroke or neurodegenerative disease.

How to test the Hypoglossal Nerve

To test the hypoglossal nerve, ask the patient to stick out their tongue. If the tongue deviates to one side, this indicates hypoglossal nerve dysfunction on the side of deviation. Then ask them to move their tongue from side to side rapidly. Additionally, listen for dysarthria when the patient is speaking as described above.

Cranial Nerve Assessment Cheat sheetCranial Nerve Assessment Cheat Sheet

How’s that for a refresher?  Although we may have forgotten some of the in’s and out’s of the cranial nerve assessment, this should serve as a reminder for how to examine cranial nerves. Hopefully, after reading this, you can feel more confident in your neurologic assessment!

If you need an easy cranial nerve assessment handout, you can download my handout here! This is the perfect cheat-sheet that you can refer to in practice when assessing cranial nerves!

References:

Gelb, D. (2019). The detailed neurologic examination in adults. In UpToDate. Retrieved from https://www.uptodate.com/contents/the-detailed-neurologic-examination-in-adults

Lee, A. G. (2019). Third cranial nerve (oculomotor nerve) palsy in adults. In UpToDate. Retrieved from https://www.uptodate.com/contents/third-cranial-nerve-oculomotor-nerve-palsy-in-adults

Lee, A. G. (2019). Fourth cranial nerve (trochlear nerve) palsy. In UpToDate. Retrieved from https://www.uptodate.com/contents/fourth-cranial-nerve-trochlear-nerve-palsy

Mullen, M. T. (2014). Differentiating Facial Weakness Caused by Bell’s Palsy vs. Acute Stroke. Journal of Emergency Medical Services39(5). Retrieved from https://www.jems.com/2014/05/07/differentiating-facial-weakness-caused-b

Oculomotor Nerve. (n.d.). Retrieved from https://www.sciencedirect.com/topics/neuroscience/oculomotor-nerve

Olfactory Nerve. (n.d.). Retrieved from https://www.sciencedirect.com/topics/neuroscience/olfactory-nerve

Rea, P. (2014). Clinical Anatomy of the Cranial Nerves. Cambridge, MA: Academic Press.

Trigeminal Nerve. (n.d.). Retrieved from https://www.sciencedirect.com/topics/medicine-and-dentistry/trigeminal-nerve