Tachycardia , also called tachyarrhythmia , is a heartbeat that exceeds the normal resting rate. In general, a resting heartbeat of more than 100 beats per minute is accepted as tachycardia in adults. Heart rate above resting numbers may be normal (as with exercise) or abnormal (such as electrical problems in the heart).
Video Tachycardia
Definitions
The upper threshold of normal human heart resting pulses is based on age. The cutoff value for tachycardia in different age groups is quite standard; Typical pieces are listed below:
- 1-2 days: Tachycardia & gt; 159 beats per minute (bpm)
- 3-6 days: Tachycardia & gt; 166 bpm
- 1-3 weeks: Tachycardia & gt; 182 bpm
- 1-2 months: Tachycardia & gt; 179 bpm
- 3-5 months: Tachycardia & gt; 186 bpm
- 6-11 months: Tachycardia & gt; 169 bpm
- 1-2 years: Tachycardia & gt; 151 bpm
- 3-4 years: Tachycardia & gt; 137 bpm
- 5-7 years: Tachycardia & gt; 133 bpm
- 8-11 years: Tachycardia & gt; 130 bpm
- 12-15 years: Tachycardia & gt; 119 bpm
- & gt; 15 years - adults: Tachycardia & gt; 100 bpm
Heart rate is considered in the context of prevailing clinical features. For example: in sepsis & gt; 90 bpm is considered tachycardia.
When the heart beats excessively or rapidly, the heart pumps less efficiently and provides less blood flow throughout the body, including the heart itself. Increased heart rate also causes increased work and oxygen demand by the heart, which can lead to ischemic associated rates.
Relative tachycardia involves an increase in rates greater than expected in a particular disease state.
Maps Tachycardia
Cause
Some causes of tachycardia include:
Differential diagnosis
The electrocardiogram (ECG) is used to classify the type of tachycardia. They can be classified into narrow and wide complexes based on QRS complexes. The order presented is at least common:
- Complex narrow
- Sinus tachycardia, derived from the sino-atrial node (SA), near the superior cava vein
- Atrial fibrillation
- Atrial flutter
- AV nodal reentrant tachycardia
- Accessory path mediated tachycardia
- Atrial tachycardia
- Multifocal atrial tachycardia
- Junctional tachycardia
- Complex area
- Ventricular tachycardia, any tachycardia originating from the ventricles
- Any narrow complex tachycardia combined with problems with cardiac conduction systems, often called "supraventricular tachycardia with abnormalities"
- Complex tachycardia with accessory conduction pathways, often called "supraventricular tachycardia with pre-excitation" (eg Wolff-Parkinson-White syndrome)
- Tracked pacemaker or pacemaker-mediated tachycardia
Tachycardia may be classified as a narrow complex tachycardia (supraventricular tachycardias) or wide complex tachycardia. Narrow and wide refers to the width of the QRS complex on the ECG. The narrow complex tachycardia tends to come from the atria, whereas the broad complex tachycardia tends to come from the ventricles. Tachycardia may be further classified as regular or irregular.
Sinus
The body has 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 unexpected changes in the bloodstream. The most common cause of the latter is orthostatic hypotension (also called postural hypotension). Fever, hyperventilation, diarrhea and severe infections may also cause tachycardia, especially as metabolic needs increase.
Increased stimulation of the sympathetic nervous system causes the heart rate to increase, either 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 has a similar effect. Increased sympathetic stimulation is usually due to physical or psychological stress. This is the basis for what is called a fight-or-flight response, but such stimulation can also be caused by stimulants such as ephedrine, amphetamine or cocaine. Certain endocrine disorders such as pheochromocytoma can also cause epinephrine release and may cause tachycardia independent of nervous system stimulation. Hyperthyroidism can also cause tachycardia. The upper limit of normal levels for sinus tachycardia is considered to be 220 bpm minus age.
Ventricle
Ventricular tachycardia (VT or V-tach) is a potentially life-threatening cardiac arrhythmia originating from the ventricle. Usually complex and regular tachycardia at rates between 120 and 250 beats per minute.
Both of these rhythms usually last only for a few seconds to minutes (paroxysmal tachycardia) , but if VT persists it is very dangerous, often leading to ventricular fibrillation.
Supraventricular
This is a type of tachycardia that originates from the top of the ventricles, such as the atria. Sometimes known as paroxysmal atrial tachycardia (PAT). Several types of supraventricular tachycardia are known to exist.
Atrial fibrillation
Atrial fibrillation is one of the most common cardiac arrhythmias. In general, it is an irregular and narrow complex rhythm. However, it may show a wide QRS complex on ECG if there is a block of bundle branches. At a high level, the QRS complex may also become widespread because of the Ashman phenomenon. It may be difficult to determine the regularity of the rhythm when the rate exceeds 150 beats per minute. Depending on the patient's health and other variables such as drugs taken to control the rate, atrial fibrillation can cause heart rates ranging from 50 to 250 beats per minute (or even higher if the accessory path is present). However, the onset of new-onset fibrillation tends to appear with numbers between 100 and 150 beats per minute.
AV nodal reentrant tachycardia
AV nodal reentrant tachycardia (AVNRT) is the most common reentrant tachycardia. This is a common narrow complex tachycardia that usually responds well to Valsalva maneuvers or adenosine drugs. However, unstable patients sometimes require synchronized cardioversion. The definitive treatment may include catheter ablation.
AV reentrant tachycardia
AV reentrant tachycardia (AVRT) requires an accessory path for maintenance. AVRT may involve orthodromic conduction (where the impulse travels through the AV node to the ventricle and returns to the atria through an accessory pathway) or antidromic conduction (which pushes the way down the accessory path and back to the atria via the AV node). Orthodromic conduction usually produces narrow complex tachycardia, and antidromic conduction usually produces complex tachycardia that often mimics ventricular tachycardia. Most antiarrhythmias are contraindicated in AVRT emergency care, because they can paradoxically increase conduction in the accessory pathway.
Junctional tachycardia
Junctional tachycardia is an automatic tachycardia derived from an AV connection. It tends to be a complex and narrow order of tachycardia and may be a sign of digitalis toxicity.
Management
Management of tachycardia depends on the type (complex and narrow complex), whether the person is stable or unstable, and whether this instability is caused by tachycardia. Unstable means that important organ function is affected or heart attack will happen soon.
Unstable
In those who are unstable with a narrow complex tachycardia, intravenous adenosine can be tried. In all others cardioversion is immediately recommended.
Terminology
The word tachycardia came into English from the New Latin as a neoclassical compound constructed from a composite form of tachy - - cardia , which is derived from the Greek language? ???? tachys , "fast, fast" and ??????, kardia , "heart". As a matter of both choices of use in medical literature and idioms in natural language, the words tachycardia and tachyarrhythmia are usually used interchangeably, or loosely enough so that the exact differentiation is not explicit. Some careful writers try to maintain the logical differentiation between them, which is reflected in the main medical dictionary and the main general dictionary. The difference is that the tachycardia is reserved for the rapid heartbeat itself, regardless of its cause, physiological or pathological (ie, from a healthy response to exercise or from cardiac arrhythmias), and that tachyarrhythmia is reserved for pathological forms (ie rapid-rate arrhythmias). This is why five of the above mentioned dictionaries do not include cross references that indicate a synonym between their entries for two words (as they do elsewhere whenever the synonym is intended), and that is why one of of them explicitly stipulate that the two words are not confused. But prescriptions may never be applicable to general use, not only because much of the existing medical literature ignores them even when the words stand alone but also because the terms for certain types of arrhythmia (the standard of adjectives and nouns) are deeply established idiomatic version of tachycardia as the more commonly used version. So SVT is called supraventricular tachycardia more than twice as often as supraventricular tachyarrhythmia; moreover, the two terms are always exactly the same - in natural language there is no such term as "healthy/physiological supraventricular tachycardia". The same theme also applies to AVRT and AVNRT. So this couple is an example when certain recipes (which may be preserved 50 or 100 years earlier) can no longer be enforced without breaking idioms. But the power to differentiate in an idiomatic way is not lost, no matter, because when the physiological tachycardia specification is required, the phrase correctly conveys it.
References
External links
Source of the article : Wikipedia
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