The normal heart rate is 60 - 90 beats per minute and when the heart rate increases to more than 100 beats per minute, it is known as tachycardia. So when you have a heart disease or any abnormality in the heart, the heart's electrical system is affected, which leads to abnormal impulses and heart rate. However, you can suffer from tachycardia when there is no structural damage to the heart by valve-related issues, regurgitation, blockage/obstruction of the arteries or damage of the heart muscles but by an abnormality in the electrical signalling of the heart. Dr Santosh Dora, Consultant cardiology and electrophysiology, Asian Heart Institute, Mumbai explains about causes fo tachycardia when it is not due to a heart disease.
1. Automaticity
The heart rate is nothing but electrical impulses that control the pumping of the heart. So every time the heart pumps, your heart beats. These electrical signals pass from the upper chamber to the lower chamber through a single definite route known as AV node. Although the normal heart rate is 60 - 90 beats per minute, when you perform a heavy exercise, it might increase to 120/130 beats per minute, which is not a cause for concern. However, in some cases, the muscles of the upper and lower chamber are hyperactivated without any known cause (idiopathy). So hyperactivity in the upper chamber causes atrial tachycardia and in the lower chamber of the heart, it leads to ventricular tachycardia. Whatever is the case, the abnormal heart rate reaches to 140 per minute. Here's everything you need to know about arrhythmia or irregular heart beat.
2. Abnormal conductions
The second common cause is abnormal conductions in which instead of following a single route, the electrical impulses take 2 or more routes to conduct the impulses. This is commonly seen from birth or with age. So the electrical impulses travel to the lower chamber through one route and travel up to the upper chamber through another route, leading to tachycardia.
3. Triggered activity
This is similar to automaticity, but, the only difference is that the heart rate is triggered by an outside factor. It could be due to medications or viral infection, which causes hyperactivity or increased heart rate. There are some situations that can lead to tachycardia, which can be treated by dealing with the underlying causes of the condition. This inlcudes anemia, bleeding, fever, injury or pain, infection and thyrotoxicosis (hyperthyroidism). In the case of thyrotoxicosis, the electrical impulse stops at sinus node, causing regional hyperactivity. This is known as sinus tachycardia in which the heart rate goes up to 130 - 140 beats per minute. Read about tachycardia or increased heart rate — 5 causes that indicate heart disease.
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