Read more about this disease, some with Classification – Types – Signs and symptoms – Genetics – Pathophysiology – Diagnosis – Screening – Prevention – Treatment and management – Cures and much more, some including pictures and video when available.
The word tachycardia comes from the Greek words tachys (rapid or accelerated) and kardia (of the heart).
Tachycardia typically refers to a heartrate that exceeds the range of the normal resting heartrate, based upon age:[1]
Tachycardia typically refers to the ventricular rate, but can also refer to an elevated atrial rate while the ventricular rate remains unaffected.[2]
When the heart beats rapidly preload or afterload may be negatively affected, causing the heart to pump blood less efficiently. The increased heartbeat leads to increased myocardial oxygen demand, which accounts for the shortness of breath felt during an acute coronary event. Acute oxygen deficiency leads to angina; chronic oxygen deficiency causes ischaemic heart disease and may lead to myocardial infarction.[2]
The body contains several feedback mechanisms to maintain adequate blood flow and blood pressure. If blood pressure decreases, the heart beats faster in an attempt to raise it. This is called reflex tachycardia.
This can happen in response to a decrease in blood volume (through dehydration or bleeding), or an unexpected change in blood flow. The most common cause of the latter is orthostatic hypotension (also called postural hypotension), a sudden drop of blood pressure that occurs with a change in body position (e.g., going from lying down to standing up). When tachycardia occurs for this reason, it is called postural orthostatic tachycardia syndrome (POTS).
Fever, hyperventilation and infection leading to sepsis are also common causes of tachycardia, primarily due to increase in metabolic demands and compensatory increase in heart rate.
An increase in sympathetic nervous system stimulation causes the heart rate to increase, both by the direct action of sympathetic nerve fibers on the heart and by causing the endocrine system to release hormones such as epinephrine (adrenaline), which have a similar effect. Increased sympathetic stimulation is usually due to physical or psychological stress (the so-called “fight or flight” response), but can also be induced by stimulants such as amphetamines.
[tubepress mode=’tag’, tagValue=’Tachycardia’]