Advanced EKGs - Ventricular Tachycardia (Classification & Localization)

Summary

This video explores various types of ventricular tachycardia (VT), covering key patterns like bundle branch reentry VT, slow VT, accelerated idioventricular rhythm (AIVR), and ventricular flutter. It explains their distinct characteristics, including axis deviations, QRS patterns, and ventricular rates, while highlighting the potential risks and diagnostic challenges. The video emphasizes the importance of accurate identification, particularly in complex cases, and outlines how certain rhythms may present in patients with structural heart disease, infarction scars, or those on antiarrhythmic medications. The video concludes by recommending further resources on EKG interpretation.

Takeaways

• 😀 Bundle branch reentry VT involves a reentrant circuit between the right and left bundle branches, often seen in patients with structural heart disease.
• 😀 In bundle branch reentry VT, the ventricular rate is very fast (usually over 200 bpm) and can cause syncope and hemodynamic instability.
• 😀 Slow VT is a type of ventricular tachycardia with a slower rate (around 120 bpm) and can be confused with SVT with aberrancy.
• 😀 Slow VT can be induced by antiarrhythmic medications, large infarct scars, or dilated chambers, and may evade detection by ICDs if the rate is below the detection threshold.
• 😀 Accelerated Idioventricular Rhythm (AIVR) typically occurs after reperfusion in acute MI and has a rate of 50–100 bpm.
• 😀 AIVR can be mistaken for sinus with aberrancy due to its narrow QRS complex and occasional P waves, but the presence of fusion and capture beats indicates a ventricular origin.
• 😀 Iso-rhythmic AV dissociation occurs in AIVR, where the sinus node fires at almost the same rate as the ventricular rhythm, causing P waves to appear before QRS complexes.
• 😀 Ventricular flutter is a high-rate, chaotic rhythm (over 250 bpm) with no isoelectric points and resembles a sine wave pattern.
• 😀 Ventricular flutter almost always degenerates into ventricular fibrillation if not treated quickly.
• 😀 The prognosis of bundle branch reentry VT is similar to scar-based VT due to its association with structural heart disease and baseline QRS prolongation.

Q & A

What is the defining feature of a typical ventricular tachycardia (VT) on an EKG?

Ventricular tachycardia (VT) is characterized by a wide QRS complex, usually greater than 120 milliseconds, with no discernible P waves. The rhythm is typically fast, with a rate above 100 beats per minute.

How can you differentiate idiopathic VT from other forms of VT?

Idiopathic VT is usually seen in patients with no significant heart disease, has a normal QRS interval (less than 120 milliseconds), and is often slower than VT due to structural issues. This makes it easier to distinguish from VT related to scar tissue or bundle branch reentry.

What is the significance of the left axis deviation in VT, and how does it affect diagnosis?

Left axis deviation in VT can indicate that the impulse is originating from the left ventricle or a more superior region of the heart. This can help distinguish different types of VT based on the axis deviation observed in the EKG.

What is a bundle branch reentry VT, and how does it occur?

Bundle branch reentry VT occurs due to a reentrant circuit involving both the right and left bundle branches. The impulse travels slowly across non-specialized myocardium, which causes a block and reentry, leading to a fast rhythm often exceeding 200 beats per minute.

What are the primary causes of bundle branch reentry VT?

Bundle branch reentry VT is commonly seen in patients with advanced structural heart disease, such as myocardial infarction, heart failure, or other conditions that cause baseline QRS prolongation.

What makes slow VT different from classic VT?

Slow VT is characterized by a slower heart rate, typically around 120 beats per minute, which is below the usual cutoff for classic VT (which is over 150 bpm). It can be mistaken for SVT with aberrancy, especially in patients with an ICD.

What conditions can lead to slow VT?

Slow VT is most commonly seen in patients who are taking antiarrhythmic medications, have large infarct scars, or possess a dilated heart chamber that creates a larger re-entrant circuit.

Why is it important to distinguish slow VT from other arrhythmias, such as SVT with aberrancy?

Distinguishing slow VT from other arrhythmias, such as SVT with aberrancy, is crucial because slow VT can sometimes fall below the detection limit of ICD devices, meaning the device might not deliver a shock when necessary.

What is an accelerated idioventricular rhythm (AIVR), and when does it typically occur?

AIVR is a slower ventricular rhythm with a rate between 50-100 beats per minute, often observed in the 24 hours after reperfusion in patients who have suffered an acute myocardial infarction (MI).

What is the characteristic EKG pattern of ventricular flutter, and why is it life-threatening?

Ventricular flutter is characterized by an extremely fast rate (over 250 bpm) and a sinusoidal wave pattern where QRS complexes and T waves merge. This rhythm is usually postless and degenerates rapidly into ventricular fibrillation, which is fatal without intervention.