What causes reentry in the heart?

Reentry, due to a circuit within the myocardium, occurs when a propagating impulse fails to die out after normal activation of the heart and persists as a result of continuous activity around the circuit to re-excite the heart after the refractory period has ended; it is the electrophysiologic mechanism responsible for …

What is a reentrant tachycardia definition?

AV-nodal reentrant tachycardia (AVNRT) is a type of abnormal fast heart rhythm. It is a type of supraventricular tachycardia (SVT), meaning that it originates from a location within the heart above the bundle of His. AV nodal reentrant tachycardia is the most common regular supraventricular tachycardia.

What is the difference between AVRT and AVNRT?

In typical AVNRT, retrograde P waves occur early, so we either don’t see them (buried in QRS) or partially see them (pseudo R’ wave at terminal portion of QRS complex) In AVRT, retrograde P waves occur later, with a long RP interval > 70 msec.

What are the two main types of re entrant cardiac rhythms?

There are two broad categories of reentrant tachycardias based on where in the heart they occur: supraventricular tachycardias (SVT); and ventricular tachycardias (VT), including ventricular fibrillation (VF).

When does reentry occur?

As described elsewhere, conduction blocks can cause bradycardia; however, they can also cause tachycardia. This occurs when impaired conduction leads to a phenomenon termed “reentry.” In fact, this mechanism may account for most tachyarrhythmias found in patients.

What is functional reentry?

In functional reentry, the reentrant impulse propagates around an area with a functional (i.e. unassociated with an anatomical barrier) conduction block. In the leading circle concept, during wave rotation, the wavefront impinges on its refractory tail.

How does reentry cause an arrhythmia?

Re-entry ventricular arrhythmia is a type of paroxysmal tachycardia occurring in the ventricle where the cause of the arrhythmia is due to the electric signal not completing the normal circuit, but rather an alternative circuit looping back upon itself. There develops a self-perpetuating rapid and abnormal activation.

How does adenosine work in SVT?

Adenosine is one of components of RNA, but given intravenously, it works to terminate SVTs by binding to the AV node’s A1 receptors. This inhibits adenylyl cyclase, ultimately increasing potassium efflux from the cell, causing hyperpolarization, and thereby “blocking” the AV node.

What is AV nodal reentrant tachycardia?

Atrioventricular nodal reentrant tachycardia (AVNRT) is a regular supraventricular tachycardia (SVT) that results from the formation of a reentry circuit confined to the AV node and perinodal atrial tissue. Because of its abrupt onset and termination, AVNRT is categorized as a paroxysmal SVT (PSVT).

What is the reentry phenomenon?

Cardiology The reexcitation of a region of the heart by a single electrical impulse, which may cause ectopic beats or tachyarrhythmia; RE is the common cause of paroxysmal atrial or supraventricular arrhythmia, which is coupled to premature ventricular depolarization.

Where in the heart do reentrant circuits form?

Most reentrant circuits are located above the ventricles, consequently, other supraventricular tachycardias can be confused with reentrant arrhythmias.

What is the cure for tachycardia?

Treatment for sustained ventricular tachycardia. Sustained ventricular tachycardia often requires urgent medical treatment,as this condition may sometimes lead to sudden cardiac death.

  • Preventing episodes of a fast heart rate.
  • Monitor and treat existing disease.

    • What is reentry tachycardia?

    Reentry Tachycardia. It is a reentry tachycardia that employs both the AV node and an accessory pathway connecting the atria and ventricles. From: Critical Heart Disease in Infants and Children (Second Edition), 2006

    What are possible causes of tachycardia?

    Possible side effects and reactions to certain medicines or treatments.

  • Some forms of heart disease cause damage to the heart tissues as well as a poor blood supply.
  • Congenital abnormal electrical pathways in people’s heart.
  • Stress,anxiety,shocks and other psychological conditions can cause tachycardia.

    • What causes paroxysmal SVT?

    Atrioventricular Nodal Re-entrant Tachycardia (AVNRT) Atrioventricular nodal re-entrant tachycardia (AVNRT) is the most common cause of PSVT.

  • Wolff-Parkinson-White Syndrome (WPW) Wolff-Parkinson-White syndrome occurs when an extra muscle fiber connects the upper and lower chambers of the heart.
  • Atrial Tachycardia.