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
- 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
- trouble exercising
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
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
- 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.