Sinus tachycardia: Everything you need to know

Medically reviewed by Payal Kohli, MD 

Written by Jamie Eske

Tachycardia is when the heart beats faster than normal. There are different types of tachycardia, depending on the cause. Sinus tachycardia is when the sinus node, which is the natural pacemaker of the heart, fires electrical impulses abnormally quickly.

People can have either normal or inappropriate sinus tachycardia. Normal sinus tachycardia refers to a physiological increased heart rate that occurs in response to specific factors, such as stress, exercise, or a fever.

Inappropriate sinus tachycardia has no known cause. People who have it may have an increased heart rate all of the time, even at rest.

In this article, we discuss sinus tachycardia, including its symptoms, types, causes, and treatment options.

What is sinus tachycardia?

Sinus tachycardia refers to an increased heart rate that exceeds 100 beats per minute (bpm). The sinus node, or sinoatrial node, is a bundle of specialized electrical cells in the right upper chamber of the heart.

These cells act as the natural pacemaker of the heart by sending electrical impulses to the surrounding tissue. These impulses cause the heart to contract.

A properly functioning sinus node regulates the rhythm and speed of a person’s heart. A normal heart rate should usually be 60–80 bpm at rest, but it can sometimes range between 60 and 100 bpm, according to the American Heart Association.

In people with a heart rate that exceeds 100 bpm, the sinus node is sending electrical signals at a faster-than-normal rate.

Symptoms

Sinus tachycardia occurs when the heart rate is above 100 bpm.

In addition to a fast heart rate, people with sinus tachycardia may experience the following symptoms:

• abnormally strong or forceful heartbeats
• irregular heartbeats
• difficulty breathing
• dizziness
• fainting
• chest pain
• anxiety
• change in blood pressure

Types

People can develop sinus tachycardia for different reasons. The underlying cause will determine the likely outcome of a person with this condition.

The types of sinus tachycardia are:

• Normal sinus tachycardia, which occurs when the heart rate increases due to an identifiable reason, such as exercise, stimulants, or emotional distress.
• Inappropriate sinus tachycardia (IST), which has no identifiable cause. People who have IST may experience an increased heart rate while resting. IST can be the result of an inappropriately high “set point” for the heart.

According to the authors of a 2017 case report, doctors can sometimes misdiagnose IST as a symptom of mental health conditions, such as depression.

Causes

Most of the time, sinus tachycardia is a normal response of the cardiovascular system to triggers that increase the heart rate. Normal sinus tachycardia may occur as part of the body’s response to certain conditions, such as intense physical activity or emotional distress.

During exercise, the heart rate typically increases as it needs to pump more oxygen to the muscles.

Emotional stress or anxiety can trigger an increase in neurotransmitters, such as dopamine and epinephrine, which make the heart beat faster.

Other potential causes of normal sinus tachycardia include:

• stimulants, such as nicotine or caffeine
• alcohol
• anxiety
• stress
• low blood pressure
• infection

Less common causes of sinus tachycardia include:

• damage to cardiac tissue
• thyroid problems
• anemia

IST typically occurs without a known cause.

Diagnosis

A doctor can diagnose sinus tachycardia by reviewing a person’s medical history, performing a physical examination, and carrying out other medical tests.

Other tests that a doctor can use to diagnose sinus tachycardia include:

• blood tests
• thyroid function tests
• urinalysis

If a doctor needs more information about how a person’s heart functions, they may ask the individual to use a wearable medical device called a Holter monitor for at least 24 hours.

The basic diagnostic criteria for IST include:

• having a resting heart rate higher than 100 bpm and an average resting heart rate above 90 bpm during Holter monitoring for 24 hours
• increased heart rate and heart palpitations that result in emotional distress

Treatment
Treatments for sinus tachycardia vary depending on the underlying cause, but they usually involve a combination of lifestyle changes, medication, and, in very rare instances, surgery.

Doctors address the underlying cause or condition when treating normal sinus tachycardia and do not often treat the tachycardia itself. Treating IST can be more challenging.

Treatments for sinus tachycardia may include:

• reducing caffeine intake
• quitting smoking and avoiding other sources of nicotine
• exercising regularly
• drinking enough water
• consuming less than 2,300 milligrams of sodium per day

Sinus tachycardia is usually a benign condition, but if it is persistent, it can lead to weakness of the heart over time. Doctors refer to this as tachycardia-induced cardiomyopathy. Sometimes, a doctor may prescribe medications, such as beta-blockers, calcium channel blockers, or ivabradine, to reduce the heart rate and treat symptoms.

In a small clinical study, researchers gave people with ITS ivabradine twice a day for 6 months. Ivabradine reduced the participants’ average daytime heart rate from 103 bpm to 84 bpm.

A doctor may recommend more invasive forms of treatment, such as catheter ablation, for people with IST who do not respond to lifestyle changes or medication.

Catheter ablation delivers heat to the portions of heart tissue that cause rapid or irregular heartbeats. This procedure can help return the heart rate to normal. However, every procedure has complications, and people may still experience recurring tachycardia after catheter ablation.

People can discuss the risks and benefits of catheter ablation with a doctor.

Summary

Tachycardia occurs when the heart beats more than 100 times per minute, whether at rest or with exercise. People develop sinus tachycardia when the sinus node in the heart sends electrical impulses more quickly than normal.

It can occur as a result of a particular trigger, such as exercise, caffeine, or stress. However, sinus tachycardia without a physiologic trigger can be a result of an arrhythmia called inappropriate sinus tachycardia.

Treatments for sinus tachycardia focus on lowering the heart rate to normal by treating the underlying cause, such as infection or low blood pressure. Doctors may also recommend lifestyle changes, medications, and medical procedures, such as catheter ablation.

People who have sinus tachycardia can learn more about their treatment options by speaking with a doctor. A doctor can offer advice on ways to improve overall cardiovascular health to lower the resting heart rate.



SOURCE: MEDICAL NEWS TODAY