Sinus tachycardia is considered serious or life-threatening in patients who have had a recent

What is sinus tachycardia?

Sinus tachycardia refers to a faster-than-usual heart rhythm. Your heart has a natural pacemaker called the sinus node, which generates electrical impulses that move through your heart muscle and cause it to contract, or beat.

When these electrical impulses are transmitted normally, it’s referred to as normal sinus rhythm. Normal sinus rhythm typically results in a heart rate of 60 to 100 beats per minute.

Sometimes, these electrical impulses are sent out faster than normal, causing sinus tachycardia, which often results in a heart rate of over 100 beats per minute.

In some situations, sinus tachycardia is completely normal. For example, sinus tachycardia is expected during strenuous exercise or after being startled.

Other things that can cause sinus tachycardia include:

• anxiety or emotional distress
• fever
• some medications
• stimulants, such as caffeine or nicotine
• recreational drugs, such as cocaine

If you have sinus tachycardia with no known reason, it’s called inappropriate sinus tachycardia (IST). People with IST can have an inexplicably fast heart rate even while they’re resting.

In addition to rapid heart rate, IST can cause:

• shortness of breath
• chest pains
• dizziness or fainting
• headaches
• trouble exercising
• anxiety

Causes

Doctors aren’t sure about the exact cause of IST, but it likely involves a combination of factors, including:

• a problem with your sinus node
• unusual nerve signaling that causes your heart rate to increase
• dysfunction of the nerves that work to lower your heart rate

Treatment

IST is often hard to treat since its causes aren’t fully understood. Depending on how fast your heart rate is, your doctor might prescribe beta-blockers or calcium channel blockers to lower your heart rate.

You may also need to make some lifestyle changes, such as:

• avoiding things that could cause an increase in heart rate, such as stimulants, recreational drugs, or stressful situations
• eating a heart-healthy diet
• exercising
• maintaining a healthy weight

In severe cases that don’t respond to medication or lifestyle changes, you may need a cardiac ablation procedure. This involves using energy to destroy a tiny part of the heart tissue located in the area that’s causing tachycardia.

Sinus tachycardia is an increase in your heart rate. In many cases, it’s a sign of something simple, such as vigorous exercise or having too much caffeine. In the case of IST, however, there’s no known cause. If you have IST, your doctor will work closely with you to come up with a treatment plan. Treatment will likely involve a combination of medications and lifestyle changes.

Sinus tachycardia is a type of irregular heartbeat that is characterized by a faster than normal heart rhythm. Your heart's sinus node generates electrical impulses that travel through the heart muscle, causing it to beat.

A normal sinus rhythm has a heart rate of between 60 and 100 beats/minute. When the sinus rhythm is consistently over 100 beats/minute, it is considered inappropriate sinus tachycardia.

Sinus tachycardia causes

Several different issues can cause sinus tachycardia, many of them not well understood. The most common cause is a trigger that results in the body inappropriately signaling the nerves to increase the heart rate. With inappropriate sinus tachycardia, the heart rate stays high even when triggers are not present.

Common causes of sinus tachycardia include:

• Infection from the virus
• Pain
• Fever
• Anxiety
• Dehydration
• Heart failure
• Anemia
• Hypothyroidism
• Caffeine
• Nicotine
• Alcohol
• Illegal drugs
• Lung disease
• Heart attack
• Low blood pressure
• Sepsis
• Mercury poisoning
• Electric shock
• Drug withdrawal
• Mitral valve prolapse
• Hypoxia
• Pulmonary embolism

Sinus tachycardia risk factors

Conditions that put a strain on the heart can increase your risk of developing sinus tachycardia.

Conditions include:

• Anemia
• Diabetes
• Heart disease
• Diabetes
• Drinking too much alcohol or caffeine
• High blood pressure
• Thyroid issues, such as an overactive or underactive thyroid
• Sleep apnea
• Smoking
• Using stimulant medications
• Psychological stress

You can decrease your risk of sinus tachycardia with lifestyle changes or medical treatment for other heart conditions.

Sinus tachycardia symptoms

Many patients do not experience symptoms or show signs of sinus tachycardia. It can be a symptom of the underlying disease and may indicate how severe the condition is.

Common symptoms of sinus tachycardia include:

• Rapid heartbeat
• Shortness of breath
• Fainting
• Dizziness
• Anxiety
• Headaches
• Chest pain
• Inability or decreased ability to exercise

Symptoms of sinus tachycardia may mimic symptoms of other health problems. People with heart conditions are more likely to have sinus tachycardia symptoms.

Sinus tachycardia complications

Potential complications of sinus tachycardia include:

• Blood clots that lead to a heart attack or stroke
• Heart failure if the heart cannot pump enough blood
• Loss of consciousness or fainting
• Sudden death

Sinus tachycardia diagnosis

Your doctor will diagnose sinus tachycardia by taking your medical history, performing a physical exam, and ordering diagnostic testing.

During the physical exam, your doctor will check your pulse for your heart rate and try to understand if there are other causes for your fast heart rate. If your doctor suspects you have tachycardia, he or she will order tests to determine what type of tachycardia you have. Treatment will vary based on what type of tachycardia you have.

Diagnostic tests your doctor may order include:

• Electrocardiogram — can analyze the heart’s electrical rhythm
• Holter monitor —  can evaluate your heart rate over time
• Blood tests
• Echocardiogram
• Chest X-ray

Sinus tachycardia treatment

In many cases, treatment is not necessary for sinus tachycardia. If an underlying condition is causing your symptoms, it needs to be treated.

Treatments for sinus tachycardia include:

• Medications — medications such as beta-blockers or calcium channel blockers are used to lower your heart rate
• Lifestyle changes — your doctor may recommend lifestyle changes such as eating a healthy diet, exercising, maintaining a healthy weight, and avoiding anything that may increase your heart rate, such as taking recreational drugs or stimulants
• Cardiac ablation — if medications and lifestyle changes are not effective, you may need a procedure to destroy the heart tissue area that is causing problems

When to seek care

If your symptoms suddenly become more severe or frequent, call your doctor. If you are experiencing chest pain or shortness of breath, seek immediate medical care.

Author: Zachary Aust, MD (Assistant Professor of EM/Attending Physician, UTSW – Dallas, TX) // Reviewed by: Andy Grock, MD; Alex Koyfman, MD (@EMHighAK); Brit Long, MD (@long_brit)

Case:

A 34-year-old female presents to the emergency department due to a high heart rate. She noticed that her heart rate has been averaging 110 bpm on her smart watch monitor for the last 2 days. She denies any additional symptoms, no chest pain, shortness of breath. She denies any recent travel, no URI symptoms. She denies any medical problems, previous surgeries or being on any medications including OCPs. She denies any history of smoking, alcohol or drug abuse. On exam vitals show a regular rate and rhythm at 110 bpm, blood pressure is 120/70, respirations are 12, pulse ox is 100% on room air, and she is afebrile. Heart and lung exam is normal, other than the tachycardia. There is no abdominal tenderness. She is able to ambulate without change in vitals or symptoms. Labs show a normal CBC, CMP, TSH, Negative HCG. EKG shows sinus tachycardia at a rate of 110bpm. She is given 1L of IVF without change in vitals.

What additional history, exam or workup (if any) should be done? What is this patient’s disposition?

Early on in my residency training I remember one of my attendings, Dr. Raymond Fowler telling me one of the important rules of emergency medicine, “Always explain the tachycardia”.  Elevated heart rate may be one of the first signs we recognize that something more insidious is wrong with the patient. When a patient in the emergency department has sinus tachycardia our job as emergency physicians is to identify and treat of the underlying pathology1-4. This is done with a HPI, review of systems, physical exam and as indicated further diagnostic studies1,2.  The full differential diagnosis of sinus tachycardia in isolation is extensive ranging from benign etiologies such as anxiety to severely life threatening etiologies such as sepsis.  Discharging a patient with abnormal vital signs has been linked to unanticipated death. One study when looking at a population of patients that had unexpected death within 7 days of ED discharge found that of those that had abnormal vital signs at time of discharge tachycardia was present in 83% of the cases4,5. Another study looking at patients with early death after being discharged from the ED found that tachycardia was the most common abnormal vital signs and that it tended to persist despite interventions5. However, another study looking at revisits in a pediatric population found that while tachycardia at discharge was independently associated with an increased risk in ED revisit rate (relative risk of 1.3), there was no clinically important intervention required at this revisit6.

What do we do, however, when we are not able to explain the tachycardia or the patient is not responding to treatment as expected? At this point there are two large questions.

#1. Am I missing anything?

#2. What is this patient’s disposition?

This article focuses on these two questions. The first part will look at a more systematic mental model to double check ourselves in the situation where we have an unexplained sinus tachycardia. This mental model will be for those few cases where the patient requires a second look, where no obvious cause has been found or the patient is not responding to treatment as expected. In these scenarios it is important for us to have a cognitive stop point to reevaluate. We should utilize a framework to systematically ensure we have fully evaluated and treated any possible underlying life threats4. The second part will examine the disposition of the patient with unexplained sinus tachycardia. While this question is a largely evidence free zone, I hope to give some guidance and possible solutions.

Background

In adults, sinus tachycardia is a heart rate greater than 100 beats per minute (bpm) originating from the sinoatrial (SA) node1-3,7. Pediatric rate cut off for tachycardia varies with age but again is defined as a heart rate great than what the normal appropriate resting heart rate for that particular age range, again originating from the SA node8. For the most part we will be referring to normal sinus tachycardia, which we encounter most often in the emergency department. Inappropriate sinus tachycardia is a different entity which will be discussed later1-3,7.

The differential diagnosis of sinus tachycardia is long. The elevation in heart rate may be normal under stress or during exercise3. Regarding emergent underlying causes, it may be helpful to think of etiologies of tachycardia as anything that could cause a need for increased cardiac output. This cardiac output increase is often due to need for increased oxygen delivery. Factors such as hypoxia, hemorrhage, or even fever can increase the demand of tissue for oxygen and thus lead to a compensatory increase in heart rate. Tachycardia may be present both from many medications or drugs. The removal of substances, causing a withdrawal state, is another etiology1- 3,7.

Many of these underlying etiologies may be obvious initially. A patient’s history and physical often will give us strong clues with additional evidence coming back on diagnostic workups. What I present here is not suggested for the initial evaluation as this would cognitively slow us. This is designed for the second look when the pieces do not fit together as they should. Here is the mental model in full, and while much of this happens in tandem, for sake of digestion it will be laid out in list format.

Vital Signs

Start with double checking vital signs. This prompts us to do a reassessment and evaluate where we are. Do they have any other explanation on their vitals that could contribute to the heart rate?

• Heart Rate
  • Does the patient still have tachycardia?
  • Has there been any change increase or decrease after intervention?
• Blood Pressure
  • What is the patients blood pressure trend?
  • Have they had any hypotension?
  • Do they have a widened or narrowed pulse pressure?
• SPO2
  • Any Hypoxia?
  • Are we getting a good waveform on the SPO2?
    • Poor waveforms more often indicate decreased perfusion than hypoxia.
  • Respiratory Rate
  • Temperature
    • Do we have a recent and accurate temperate?
      • A core temperature may be indicated.
    • Glucose POC

EKG

Then next question is: Is this actually sinus tachycardia? Looking at the initial or even repeating the EKG will be helpful here.

• QRS (wide/narrow)
• Regular/Irregular

In general sinus tachycardia should be regular and narrow complex (excluding having a bundle branch block), wide complex tachycardia should make you think Ventricular Tachycardia until proven otherwise.

• P waves?
  • Are there p waves or is this possibly another SVT?
• Origin from SA node?
  • Upright p waves in I, II, aVL
  • Negative p waves aVR
• Flutter?
  • Then ask are we missing another underlying arrhythmia such as Atrial Flutter. Think about this especially with the rate being consistently around 150 bpm (+/-20 bpm)

History

• Repeat ROS
• Infectious
• Cardiopulmonary
• Tox

Have we done a comprehensive review of symptoms? Have we asked about any possible infectious etiologies for the patient’s symptoms? Is there any history of medications or substances that could be causing the tachycardia either from acute ingestion or withdrawal? Is the patient having any shortness of breath at rest or with exertion?

Physical Exam

Is there anything we have overlooked on physical exam? A more detailed exam may provide a clue to the underlying etiology.

• General
  • On repeat assessment how does the patient generally appear, what is your overall gestalt?
• Cardiopulmonary
  • Are there any abnormal sounds that may point to a diagnosis?
• Abdominal Tenderness?
• Neuro/Tox
  • Pupils
  • Clonus/Rigidity
  • Reflexes
  • All may help indicate another underlying cause such as toxic ingestion or withdrawal.
• Skin
  • Diaphoretic/Dry?
    • May point to Toxic or infectious etiology
  • Infections/Wounds/Rashes
    • Have we overlooked an infectious source?
    • Axilla, Sacral, GU
  • Overall Volume Status?
    • Do they have edema?
    • JVD?
    • How are their mucous membranes?

POCUS

My personal favorite way to assess for volume status is using point of care ultrasound (POCUS) which is the next part of our mental model. For this I believe doing the RUSH exam (Rapid Ultrasound for Shock and Hypotension) is a helpful framework. While it was derived to help identify unexplained hypotension, if we accept that sinus tachycardia may be an early indicator of shock, we can utilize this general approach to help reevaluate as clinically indicated.

Are there signs of pericardial effusion or tamponade? Are the ventricles normal sized? How is the cardiac squeeze? Any signs of fluid or PTX in the lungs? Does the IVC indicate to you that the patient is severely volume up or down. Any signs of AAA? Any signs of free fluid in the abdomen?

Diagnostics

Are there any laboratory abnormalities that either we overlooked or need to consider adding on?

• CBC
• Chem
  • Have we fully elevated for anemia and electrolyte disturbances?
• TSH
• D-Dimer
  • Is this patient low to intermediate risk for pulmonary embolism?
• Tox
  • Ethanol
  • ASA/APAP
  • Serum Osm
    • On repeat exam is there any more concern for toxic ingestion we may consider adding on APAP/ASA or looking for toxic alcohols.
  • Lactate
  • Troponin
    • Could this be ACS or myocarditis?
  • Is there additional imaging indicated?

This is not saying you should just blindly order all of these labs; we want to order them only when clinically indicated. These are listed here as a cognitive stop point: have we at least considered these possible life threats?

Treatments

Finally, have we adequately treated possible underlying causes?

• IVF
  • Have we rehydrated as clinically indicated?
• Analgesia
  • Have we provided adequate analgesia?
• Benzos
  • Are they requiring benzodiazepines for withdrawal?
• Additional Resuscitation
  • Have we addressed all potential sources of shock for the patient in front of us? Does the patient require blood, a procedure to address obstructive shock, or other source control?
• Iatrogenic
  • Is it possible they weren’t tachycardia to begin with but we have given them something to stimulate the heart rate such as albuterol?

Utilizing this mental model provides a thorough approach to the patient with continued unexplained sinus tachycardia.

Disposition

What now for the patient who after all of this, still continues to have a high heart rate? This will obviously be very dependent on the scenario, but the elephant in the room we need to address is: can we discharge the patient in sinus tachycardia?

In short: yes, but it depends.

This is going to be variable based on providers risk tolerance, patient status and ability to follow up. Let’s use the example of the well appearing patient, without significant co morbidities. They may have presented due to palpitations or noticing their heart rate was elevated on a home monitoring device. In this case let us say we have a patient with either:

• Asymptomatic but persistent sinus tachycardia
• Sinus tachycardia with a found/treated underlying etiology that would otherwise not make you concerned for discharge if not for the heart rate.

There are other conditions such as inappropriate sinus tachycardia and sinus node reentry tachycardia that could be causing this2,3,7. It is not unreasonable to arrange for cardiology evaluation. Patients can develop a tachycardia-mediated cardiomyopathy from any tachyarrhythmia. Often the ventricular dysfunction from this is reversible. The risk seems to be greatest once reaching 110-120 bpm, the older the patient the higher likelihood they are at risk for this. The time course, however, does seem to take from a month to possibly years9. Given this fact, it may be reasonable to discharge if patient is able to get reliable cardiology follow up in a short period of time.

Pearls

• Sinus Tachycardia is often the first sign something more insidious is wrong with the patient.
• Tachycardia can be a response to anything that causes the body to have an increased oxygen demand, sympathetic stimulus, or withdrawal of a substance.
• In the ED, our job is to identify and treat underlying causes.
• When no cause is found, or the patient is not responding to treatment as expected, a more systematic mental model is needed.
• Disposition of sinus tachycardia depends on many factors, however the well-appearing asymptomatic patient does not require admission for tachycardia alone.

#FOAMED

References

1) Henning A, Krawiec C. Sinus Tachycardia. In: StatPearls. Treasure Island (FL): StatPearls Publishing; April 30, 2022.

2) Yusuf S, Camm AJ. Deciphering the sinus tachycardias. Clin Cardiol. 2005;28(6):267-276. doi:10.1002/clc.4960280603

3) Yusuf S, Camm AJ. The sinus tachycardias. Nat Clin Pract Cardiovasc Med. 2005;2(1):44-52. doi:10.1038/ncpcardio0068

4) Sklar DP, Crandall CS, Loeliger E, Edmunds K, Paul I, Helitzer DL. Unanticipated death after discharge home from the emergency department. Ann Emerg Med. 2007;49(6):735-745. doi:10.1016/j.annemergmed.2006.11.018

5) Gabayan GZ, Sun BC, Asch SM, et al. Qualitative factors in patients who die shortly after emergency department discharge. Acad Emerg Med. 2013;20(8):778-785. doi:10.1111/acem.12181

6) Wilson PM, Florin TA, Huang G, Fenchel M, Mittiga MR. Is Tachycardia at Discharge From the Pediatric Emergency Department a Cause for Concern? A Nonconcurrent Cohort Study. Ann Emerg Med. 2017;70(3):268-276.e2. doi:10.1016/j.annemergmed.2016.12.010

7) Brugada J, Katritsis DG, Arbelo E, et al. 2019 ESC Guidelines for the management of patients with supraventricular tachycardia: The Task Force for the management of patients with supraventricular tachycardia of the European Society of Cardiology (ESC) [published correction appears in Eur Heart J. 2020 Nov 21;41(44):4258]. Eur Heart J. 2020;41(5):655-720. doi:10.1093/eurheartj/ehz467

8) Fleming S, Thompson M, Stevens R, et al. Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies. Lancet. 2011;377(9770):1011-1018. doi:10.1016/S0140-6736(10)62226-X

9) Kim DY, Kim SH, Ryu KH. Tachycardia induced Cardiomyopathy. Korean Circ J. 2019;49(9):808-817. doi:10.4070/kcj.2019.0199