Tachycardia Syndrome Causes
The human heart beats at a normal rate of about 60 to 100 beats a minute during a period of rest. Tachycardia is a condition where the heart beats at a rate of more than 100 a minute. Periods of anxiety, stress or exercise can cause people to experience transient rapid heartbeats, also known as sinus tachycardia. However, when tachycardia occurs during a state of rest or without logical cause, it is considered abnormal. Tachycardia is classified into two main types. Abnormal supraventricular tachycardia, which originates in the upper chamber of the heart and ventricular tachycardias, which originates in the lower chambers of the heart.
The more common forms of tachycardia’s are:
• Paroxysmal supraventricular tachycardia, where the heart rate is roughly 140 to 200 beats in a minute, develops spontaneously, then stops and starts suddenly, but has the tendency to re-occur.
• Atrial flutter, where the upper chambers of the heart beat at a rate of 240 to 300 beats in a minute while the actual pulse rate is much slower because not all of these impulses are translated into contraction of the ventricles.
• Ventricular tachycardia is a very serious arrhythmia that is initiated in the ventricles, in which the heart rate is usually between 150 and 250.
• Atrial fibrillation is a condition where the heart beats faster and irregularly, with the upper chambers contracting upto 500 times a minute and the lower ones up to 180 times.
Sinus tachycardias is more likely to occur in those that are easily exitable, suffer from anxiety or consume large amounts of caffeine. They are also commonly seen in people with thyroid disease, fever or with certain medications like those for asthma and allergies. The occurrence of tachycardias under any of the above mentioned circumstances does not necessarily imply any underlying heart disease. Most of the severe types of tachycardia occur to those who have an underlying heart disease. They are more likely caused due to an electrical disturbance within the heart without any anatomic deformity, or by congenital defects, chronic disease of the heart valves, or chronic lung diseases. Tachycardias may also occur during the course of a heart attack.
The main symptom of tachycardia is the awareness of a rapid heartbeat, commonly known as “palpitations” of the heart. Depending on the underlying cause and extent of the tachycardia, other symptoms could possibly include a shortness of breath, actual syncope (fainting), chest pain, severe anxiety and dizziness.
