Your heart normally beats in a regular rhythm at a rate of roughly 60 to 100 beats per minute at rest. When the resting heart rate exceeds 100 beats per minute, this is called tachycardia. Many conditions and diseases can cause tachycardia. Some are related to the heart itself, while others represent the heart's response to an underlying medical condition. It's important to seek medical evaluation for a persistently elevated heart as it may signal a serious health problem.
Stimulants and Medications
Stimulants such as caffeine from coffee, tea or energy drinks and nicotine from tobacco are common causes of a temporarily elevated heart rate. Certain illegal drugs and over-the-counter and prescribed medications can also stimulate the heart and cause it to beat faster than usual. According to a June 2010 article published in "Critical Care Medicine," drugs commonly associated with an increased heart rate include:
-- bronchodilators used for asthma treatment, such as albuterol (Proair, Ventolin)
-- medications used to treat attention deficit hyperactive disorder, such as amphetamine derivatives (Adderall, Vyvanse) and methylphenidate (Ritalin, Concerta)
-- antihistamines, such as diphenhydramine (Benadryl)
-- illegal stimulants, such as cocaine
Fear, Anxiety and Stress
Fear, anxiety and stress trigger the release of adrenalin, commonly known as the fight-or-flight hormone. Adrenalin stimulates an increase in heart rate, along with other effects. This response is normal in short-term situations, but can cause frequent or persistent tachycardia in people with an anxiety disorder, including:
-- panic disorder
-- social anxiety disorder
-- generalized anxiety disorder
-- obsessive compulsive disorder
-- post-traumatic stress disorder
Circulatory and Lung Problems
The heart and lungs work together to deliver oxygen to the body organs and tissues and rid the body of carbon dioxide, a waste product of normal metabolism. Circulatory and lung problems that impair this function can lead to a low blood oxygen level, a high carbon dioxide level, or both. These abnormalities stimulate the heart to beat faster to compensate. Examples of circulatory and lung problems that frequently lead to tachycardia include:
-- congestive heart failure
-- serious congenital heart defects
-- extremely low blood pressure, or shock
-- chronic obstructive pulmonary disease
-- collapsed lung, or pneumothorax
-- a blood clot in the lung, or pulmonary embolism
Heart rate and rhythm are controlled by a network of cells -- called the conduction system -- that sends electrical signals leading to a regular, coordinated heart beat. Malfunctions in this system can lead to tachycardia and an irregular heart rhythm, or arrhythmia. Atrial tachycardia originates in the upper chambers of the heart and can cause lightheadedness, shortness of breath and palpitations -- feeling like your heart is pounding or beating irregularly. Ventricular tachycardia arises from a malfunction of the conduction system in the lower chambers of the heart. This type of tachycardia is particularly dangerous as the heart may be unable to effectively pump blood to the rest of the body. Uncorrected, ventricular tachycardia can lead to loss of consciousness, cardiac arrest and death.
Other Medical Conditions
Certain other medical conditions can lead to an elevated heart rate. For example, tachycardia is a common sign of hyperthyroidism, or an overactive thyroid gland. Low blood sugar, which frequently occurs in people with diabetes on insulin therapy, also stimulates an elevated heart rate. Anemia, or a lack of red bloods, stimulates an increase in heart rate to compensate for the reduced oxygen-carrying capacity of the blood. Anemia is frequently due to a nutritional deficiency, such as iron or vitamin B12, or bleeding. More generally, any illness that causes a fever, dehydration or intense pain can lead to a high heart rate.
Warnings and Precautions
A healthy heart can usually tolerate a temporary, mild increase in heart rate due to a minor illness. However, tachycardia can be potentially life-threatening in some situations. So it's important not to ignore this potentially serious condition. Always consult with your doctor if you have a persistently elevated heart rate. Seek emergency medical attention if you experience:
-- chest pain or tightness
-- shortness of breath or difficulty breathing
-- dizziness or fainting
Reviewed by: Tina M. St. John, M.D.