science

Re-entry ventricular arrhythmia

Re-entry ventricular arrhythmia is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Re-entry ventricular arrhythmia rather than just read about it. In short: 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.

Key takeaways

Re-entry ventricular arrhythmia belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Re-entry ventricular arrhythmia to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Re-entry ventricular arrhythmia from memory before moving on to harder problems.

Reference excerpt

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. ("Circus Movement" is another term for this.) Conditions necessary for re-entry include a combination of unidirectional block and slowed conduction. Circus movement may also occur on a smaller scale within the AV node (dual AV nodal physiology), a large bypass tract is not necessary. Re-entry is divided into two major types: [Anatomically Defined] re-entry and [Functionally Defined] re-entry. The circus movement can occur around an anatomical or functional core. Either type may occur alone, or together. Anatomically defined re-entry has a fixed anatomic pathway. Anomalous conduction via accessory pathways (APs) creates the re-entry circuit (which are also called bypass tracts), that exists between the atria and ventricles. Wolff–Parkinson–White syndrome (WPW) is an example of anatomically defined re-entry. WPW syndrome is an atrioventricular re-entrant tachycardia (AVRT), secondary to an accessory pathway that connects the epicardial surfaces of the atrium and ventricle along the AV groove. The majority of time symptomatic WPW fits the definition of AVRT (Supraventricular tachycardia) however AVNRT (dual AV nodal physiology) exist in ~10% of patients with WPW syndrome creating the possibility of spontaneous atrial fibrillation degenerating into ventricular fibrillation (VF). The fact that WPW patients are young and do not have structural heart disease, lead to using catheter ablation of the APs with the elimination of the atrial fibrillation as well as the episodes of re-entrant ventricular tachycardia. This elimination of the atrial fibrillation with ablation implies APs have some pathophysiologic role in the development of a-fib in the WPW patient. Functionally defined re-entry does not require the alternative anatomically defined circuit accessory pathways and it may not reside in just one location. Ventricular fibrillation (VF) following ventricular tachycardia (VT) may be described as a functionally defined re-entry problem caused by multiple mini re-entrant circuits spontaneously created within the ventricular myocardium. The original re-entrant circuit breaks down into multiple mini reentrant circuits. (VF becoming the grand finale of a single prolonged VT larger circus movement, propagating change in the "functional core" of the ventricular myocardium, dissipating mini reentrant circuits, exhibited as ventricular fibrillation.) Ischemia, electrolyte, pH abnormalities, or bradycardia are potential causes of functionally defined re-entry due to changes in the properties of the cardiac tissue's functional core. (No accessory pathway required). For reentry to occur, the path length of circuit should be greater than the wave length (ERP × conduction velocity) of impulse.

See also AV reentrant tachycardia AV nodal reentrant tachycardia

References

External links

Worked examples

Example 1 — a first encounter with Re-entry ventricular arrhythmia

Start with the simplest possible case. Write down what Re-entry ventricular arrhythmia claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Re-entry ventricular arrhythmia before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Re-entry ventricular arrhythmia ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Re-entry ventricular arrhythmia

In research: Re-entry ventricular arrhythmia appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Re-entry ventricular arrhythmia in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Re-entry ventricular arrhythmia is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cardiac arrhythmia, so understanding it makes those chapters shorter.
In everyday life: Look for Re-entry ventricular arrhythmia outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Re-entry ventricular arrhythmia in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Re-entry ventricular arrhythmia means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Re-entry ventricular arrhythmia out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Re-entry ventricular arrhythmia in simple terms?

Why does Re-entry ventricular arrhythmia matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Re-entry ventricular arrhythmia?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Re-entry ventricular arrhythmia.