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Inappropriate Sinus Tachycardia


Inappropriate Sinus Tachycardia

Related article: Supraventricular tachycardias.

Inappropriate sinus tachycardia is a tachycardia generated in the sinus node, wich appears at rest or in situations of mild effort, and it is accompanied by a set of symptoms that can be disabling for the patient.

The mechanisms of the inappropriate sinus tachycardia are not fully specified.

It is important to distinguish it from the sinus tachycardia itself and other similar, such as postural orthostatic tachycardia syndrome, because their symptoms can be confused 1.


Clinical Picture of Inappropriate Sinus Tachycardia

Inappropriate sinus tachycardia is a rare arrhythmia. It is more frequent in females and in the age range between 15 and 45 years.

It presents a varied symptomatology. The most common symptoms are palpitations and dyspnea, although, chest pain, dizziness, presyncope, and in some cases, syncope may also appear chest 2.

These symptoms are in relation to sinus tachycardia and they are usually triggered by mild exercise, psychological stress or postural changes.

Although symptoms can be disabling, inappropriate sinus tachycardia has a benign prognosis.

It is often confused with psychological symptoms or anxiety, which tends to delay the diagnosis.

Electrocardiogram of Inappropriate Sinus Tachycardia

Inappropriate Sinus Tachycardia

Electrocardiogram of sinus tachycardia

  • Heart Rate greater than 100 bpm.
  • Sinus P waves (positive in inferior leads and in precordial leads V2-V6).
  • All P waves are followed by a QRS complex

How to Make the Diagnosis of Inappropriate Sinus Tachycardia

The diagnosis of sinus tachycardia is made by exclusion.

It must rule out other more frequent supraventricular tachycardias as AV nodal reentrant tachycardia, atrial flutter or atrial tachycardia.

In certain cases it is necessary to make an electrophysiology study to rule out other causes of tachycardias. Other causes of "appropriate" sinus tachycardia (fever, hyperthyroidism, hypoxia, drug use, among others) should be ruled out.

The presence of sinus tachycardia in situations that are not in accordance with the physiological needs of the patient, accompanied by symptoms, may help with the diagnosis.


Treatment of Inappropriate Sinus Tachycardia

The treatment most commonly used in inappropriate sinus tachycardia are the beta-adrenergic blocking agents (beta blockers) and the non-dihydropyridine calcium channel blockers (diltiazem and verapamil).

Treatment often is initiated with low doses, and it may increase according to the symptomatology.

Also the increase in the consumption of salt and water can reduce the symptomatology.

Recently, the ivabradine (selective If channel inhibitor), a drug that acts at the level of the sinus node and which is indicated in the ischemic heart disease and heart failure. It arises as an alternative in the treatment of inappropriate sinus tachycardia 3.


Summary

Inappropriate sinus tachycardia is a rare arrhythmia, generated in the sinus node and that produces high heart rates in response to mild stimuli not related to the patient's physiological needs.

On the electrocardiogram, a sinus tachycardia is observed,and despite their significant symptoms, it has a benign prognosis.

Currently its treatment is based on the use of drugs that decrease the rate of the sinoatrial node, especially beta blockers and non-dihydropyridine calcium channel blockers.


Related article: Supraventricular tachycardias.

References

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