What is Sinus Tachycardia?

Sinus tachycardia occurs when heart rate increases, usually due to some stimulus that has affected the heart muscle. Causes of sinus tachycardia include severe fright, distress, exercise, fever, and use of recreational, over-the-counter, or prescription drugs. In many cases, sinus tachycardia is considered normal, and the heart rate often lowers itself without treatment. If sinus tachycardia is more persistent, however, it may be the result of an underlying condition. When drugs of any type are implicated in increased heart rate, drug use habits may need to be reconsidered.

The increase in heart rate known as sinus tachycardia typically occurs when the nerve bundle known as the sinoatrial (SA) node stimulates the heart to beat more rapidly. The SA node can be found in the upper portion of the right atrium of the heart. It normally produces the electrical impulses that regulate heartbeat. Most people have a normal resting heart beat of 60 to 70 beats per minute, but sinus tachycardia can cause the heart to beat much faster.

While rapid heart rate can occur with this type of tachycardia, the heart continues to function normally. The interval between beats is usually regular and the heart beat itself is normally rhythmic. Rapid heart rate is typically the only symptom of this condition.

Many of the causes of sinus tachycardia require no treatment. It's considered normal for heart rate to increase during physical activity. Extreme fear, anxiety or emotional distress can also cause a rapid heart rate. The heart rate usually returns to normal after a suitable period of rest, or after the extreme emotions have dissipated.

More dangerous causes of sinus tachycardia can include dehydration and severe bleeding. Both conditions can lead to severe fluid loss from the body. Heart rate may increase as the heart struggles to pump less blood through the veins and arteries. Both dehydration and severe bleeding can lead to serious health consequences and death.

Use of prescription, over-the-counter and recreational drugs can also lead to sinus tachycardia. Caffeine, alcohol, and ephedrine-based respiratory remedies can stimulate the SA node and lead to rapid heart rate. Recreational or "street" drugs such as cocaine or methamphetamine can also raise the heart rate. Patients with heart problems are often strongly advised to consult a physician before using caffeine, alcohol, over-the-counter cold remedies, or any prescription drugs.