Your heart's rhythm is influenced by several organs including those in the nervous, cardiovascular and endocrine systems. Normally, the heart is able to restore a healthy rhythm when common influences, such as emotions or physical activity, cause it to speed up. In some cases, however, medical conditions, drugs or other factors may cause an increased heart rate that can be dangerous if left untreated. Whether increased heart rate, or tachycardia, is dangerous depends on several factors, including how fast the heart is beating, how long it is left untreated, the type of tachycardia and the presence of underlying medical conditions. If you suspect you have an abnormal heart rhythm, seek medical attention immediately.
Definition of Tachycardia and Normal Resting Heart Rate
At age 10 and older, a normal resting heart rate is between 60 and 100 beats per minute, or bpm, according to MedlinePlus.com. The more efficiently the heart functions, the slower it needs to beat. For this reason, elite athletes or those in superior cardiovascular condition tend to have lower resting heart rates than other adults; 40 bpm is the lower limit of their normal range.
For ages 10 and older, a resting heartbeat greater than 100 bpm is considered an abnormally fast, or tachycardic, rate. At ages 1 through 9 years, normal resting heart rate is between 70 and 130 bpm. For infants that 1 through 11 months old, between 80 and 120 bpm is normal, while newborns may have heart rates as high as 190 bpm.
Complications and Symptoms of Tachycardia
Complications from tachycardia include fainting, blood clots, heart failure and sudden death, according to MayoClinic.com. Symptoms of an abnormally fast heart rate include dizziness, heart palpitations, shortness of breath and chest pain. Since tachycardia can be dangerous, seek medical attention immediately if you suspect an abnormal heart rhythm.
Measure your pulse by placing your index and middle fingers on the thumb-side of your wrist to get a radial pulse or on your neck to the right or left of your Adam's apple to get a carotid pulse. Count the number of beats for either 30 seconds or one minute to measure bpm accurately. Measure an infant's pulse by placing the same two fingers just below the biceps muscle on the inside of the arm to get a brachial pulse.
Ventricular Tachycardia
Normally, heart rhythm is set by electrical signals from a group of cells called the "sinoatrial," or SA, node in the upper portion of the heart. The SA node is the heart's pacemaker. The electrical current is sent over both upper chambers, the atria, causing them to contract. The signal then moves to the atrio-ventricular, or AV, node which causes the lower chambers to contract.
Types of tachycardia are categorized by the location of the abnormal electrical activity and fall into two main categories -- supraventricular, meaning above the ventricles, or ventricular. The most dangerous type is ventricular tachycardia, also called "V-tach," ventricular fibrilation, or "V-fib." If normal heart rhythm is not resumed within five minutes, V-tach can cause brain damage, heart damage or death, according to the Columbia University Department of Surgery. A person in V-tach without a pulse must receive CPR or be shocked with crash cart paddles or an automated external defibrilator, or AED.
Paroxysmal Supraventricular Tachycardia
Paroxysmal supraventricular tachycardia, or PSVT, is an occasional form of increased heart rate that is usually not life-threatening if you have no other medical conditions, according to the National Center for Biotechnology Information. PSVT can result from serious heart conditions or from drinking caffeine or smoking cigarettes. It can last for minutes or hours and may or may not require treatment to stop it. PSVT usually occurs in young people or babies who may not show any symptoms. Left untreated, PSVT increases the risk of heart failure. Do not try to determine whether your tachycardia is dangerous on your own since there are many types, causes and treatments of tachycardia.
References
- Columbia University Department of Surgery: Tachycardia
- MayoClinic.com: Tachycardia Complications; May 2011
- National Center for Biotechnology Information: Arrhythmias
- MayoClinic.com: Tachycardia Treatment; May 2011
- MedlinePlus.com: Pulse
- National Center for Biotechnology Information: Paroxysmal Supraventricular Tachycardia
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