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Dr A Röschl's picture

VT or SVT? Here, Both!

Submitted by Dr A Röschl on Sun, 07/30/2023 - 02:07

Complex ECGs like this one have to be approached systematically. Firstly, we can see a normal sinus rhythm. A is the first beat of a wide complex tachycardia. This must be a ventricular tachycardia. Although there is a P-wave before the first beat of the tachycardia, it is not premature. Therefore, there is no SVT with aberrant conduction. The first beat of the tachycardia looks different from the subsequent beats because there is a fusion beat present. The VT conducts 1:1 back to the atria (a small negative P-wave can be seen at the end of the QRS complex in V1).

Dr A Röschl's picture

Ventricular Tachycardia After Inferior Myocardial Infarction

Submitted by Dr A Röschl on Wed, 07/26/2023 - 06:20

76-year-old man, with a history of inferior wall myocardial infarction. He experiences recurrent episodes of brief palpitations, often lasting only 5-15 seconds. In this ECG, at the beginning, the last part of a wide-complex tachycardia is visible. After 2 sinus beats, another wide-complex tachycardia begins (with the same QRS configuration).

Dawn's picture

Wide Complex Tachycardia

Submitted by Dawn on Fri, 02/05/2021 - 21:11

This pair of ECGs feature one of our recurring themes:  wide-complex tachycardia (WCT). It is a fascinating topic, as tachycardia has many causes and many mechanisms, and wide QRS also has many causes, with the mechanism being slow conduction through the ventricles. 

Sometimes, it is not possible to diagnose the true origin of a WCT from one ECG, or even serial ECGs.  Is the tachycardia due to increased sympathetic activity (fear, dehydration, exercise, hypoxia, hypovolemia, etc.)?  Or is the fast rate due to reentry, where one impulse gets “caught” in a loop, repeating itself rapidly, and depolarizing the myocardium with each pass?  What is the location of the pacemaker that is responsible for the rhythm?  Is it a supraventricular rhythm that has suffered an intraventricular conduction delay, widening the QRS?  Or is the rhythm originating in a ventricular pacemaker, without the ability to travel on the fast highway that is the intraventricular conduction system? 

If you or your students work in an acute care setting, such as pre-hospital or emergency department, you may not be with the patient long enough or be able to conduct enough tests to determine without a doubt the answers to the above questions.  Some WCTs cause such severe symptoms that they must be dealt with quickly, to avoid rapid deterioration to ventricular fibrillation.  For that reason, there is a widely-accepted rule for WTC treatment:

TREAT ALL WIDE-COMPLEX TACHYCARDIA AS IF IT IS V TACH UNTIL PROVEN OTHERWISE.    

Dawn's picture

Wide Complex Tachycardia

Submitted by Dawn on Fri, 05/01/2020 - 16:19

The Patient:   The details of this patient’s complaints and presentation are lost, but we know he was a 66-year-old man who was being treated in the Emergency Department. His rhythm went from sinus tachycardia with non-respiratory sinus arrhythmia to multi-focal atrial tachycardia (MAT) to wide-complex tachycardia. The WCT lasted a few minutes and spontaneously converted to an irregular sinus rhythm.

Wide-complex tachycardia:  Ventricular tachycardia or aberrantly-conducted supraventricular tachycardia?  When confronted with a wide-complex tachycardia, it can be very difficult to determine whether the rhythm is ventricular or supraventricular with aberrant conduction, such as bundle branch block. The patient’s history and presentation may offer clues.  It is very important, if the patient’s hemodynamic status is at all compromised (they are “symptomatic”), the WCT should be treated as VENTRICULAR TACHYCARDIA until proven otherwise.  

There have been many lists made of the ECG features that favor a diagnosis of ventricular tachycardia. Here are two such lists:  Life In The Fast Lane, and National Institute of Health.

The ECG:  This ECG shows a regular, fast, wide-QRS rhythm.  The rate is 233 bpm.  It had a sudden onset and sudden offset (not shown on this ECG), and the rhythm lasted about 3-5 minutes. The patient felt the change in rate, but did not become hypotensive or unstable.  Some features that relate directly to the most commonly-referenced VT vs. SVT charts are:

Dawn's picture

ECG Basics: Ventricular Tachycardia

Submitted by Dawn on Wed, 12/20/2017 - 15:00

V tach is identified by:  wide QRS complexes (>.12 seconds), rate faster than 100 bpm.  In MONOMORPHIC V tach, all QRS complexes look alike.  There are other mechanisms of wide-complex tachycardia, but they can be difficult to differentiate from a single rhythm strip.  All WCT should be treated as V tach until proven otherwise.

Dawn's picture

Ventricular Tachycardia In A Patient With Myopathy

Submitted by Dawn on Tue, 12/19/2017 - 23:15

These two ECGs are from a 77-year-old woman who was complaining of palpitations and mild shortness of breath.  She stated a history of atrial fibrillation.  She was alert, with a systolic BP over 120.  At the hospital, she was found to have cardiomyopathy, resulting in global hypokinesis. She also had significant coronary artery narrowing in her left main, left anterior descending, and circumflex, which were treated with coronary artery bypass graft surgery.

The first ECG was taken on arrival of the EMS crew at the patient’s home.  It shows ventricular tachycardia, rate 226 bpm, All WCTs should be considered to be ventricular tachycardia until proven otherwise.  While WCT can sometimes be difficult to definitively diagnose in the field, this ECG has many features which favor the diagnosis of VT, including:

·         An extremely wide QRS (I measure .24 sec., the machine measures .368 sec.).

·         An extreme left axis deviation (aVF is all negative).

·         Absence of either RBBB or LBBB pattern, with a  completely negative QRS in V6.  This all negative V6 places the liklihood of the rhythm being VT to about 100%.

Dawn's picture

Atrial Fib To Cardiac Arrest

Submitted by Dawn on Sun, 07/03/2016 - 14:31

A paramedic crew responded to the office of a local physician. A 61-year-old male presented with a one-week history of chest pain and shortness of breath. He had a previously undiagnosed atrial fibrillation with rapid ventricular response and left bundle branch block, but was alert. Shortly after transport commenced, the patient became unresponsive with Torsades de Pointes, which rapidly degenerated into ventricular fibrillation. The paramedic placed pads and defibrillated within one minute.  After two minutes of compressions, the patient had a fairly regular rhythm with return of spontaneous circulation.  Transport time was short.  On catheterization, the patient was found to have severe coronary artery disease, requiring coronary artery bypass graft surgery (CABG) A balloon pump was inserted in an attempt to strengthen him for surgery.

What is the rhythm?   The 12-lead ECG presented here shows atrial fibrillation at a rate of 138 per minute.  The rhythm is irregularly-irregular with no P waves.  Since the patient had not yet been diagnosed with atrial fib, obviously no therapy had been initiated to control the rate. There is a PVC near the end of the strip.

Dawn's picture

Wide-complex Tachycardia: Ventricular Tachycardia

Submitted by Dawn on Tue, 06/14/2016 - 14:23

This ECG is from a man who was experiencing palpitations and light-headedness with near-syncope. On first look, you will see a wide-complex tachycardia (WTC) with a rate around 240 per minute.  It is difficult to assess for the presence of P waves because of the rate and the baseline artifact. 

 

The differential diagnosis of WCT includes ventricular tachycardia and supraventricular tachycardia with aberrant conduction, or interventricular conduction delay (IVCD). We should ALWAYS consider VENTRICULAR TACHYCARDIA first.  If the patient is an older adult with structural heart disease, WCT almost always proves to be VT. 

ABERRANT SVT?   In the setting of SVT with wide QRS, the most common aberrancy is right or left bundle branch block.  This ECG could be said to have a “RBBB” type pattern in V1, rSR’ and in Lead I and V6 with a wide S wave.  However, the other precordial leads do not have a RBBB pattern. 

VENTRICULAR TACHYCARDIA? There are some features of this ECG that favor the diagnosis of VENTRICULAR TACHYCARDIA (VT).  They include, but are not limited to:

* Regular, wide QRS complexes, about .14 seconds in this ECG, but varies because of difficulty in measuring the beginning and end of the QRS in each lead.  The artifact obscures the exact points of beginning and ending. The QRS complexes, especially from V2 leftward, are very “ugly”, and don’t resemble patterns we would expect with bundle branch block.

* Horizontal plane axis extremely abnormal:  Leads II, III, and aVF are negative and aVR and aVL are positive.  The biphasic Lead I indicates a nearly vertical axis at around – 90 degrees.

* There is “almost” precordial concordance, but V1 is biphasic. 

Unfortunately, we do not see capture beats or fusion beats, which would secure the diagnosis of VT. Disassociated P waves would also be a sure sign of VT, but the artifact in this ECG makes it impossible to say whether there are P waves. 

Dawn's picture

Non-Sustained Ventricular Tachycardia

Submitted by Dawn on Sat, 06/04/2016 - 14:02

This ECG was obtained from a 45-year-old man who was experiencing palpitations and lightheadedness, which he originally attributed to anxiety. There are short, but frequent periods of ventricular tachycardia, which are self-limiting.  This is called "NON-SUSTAINED VENTRICULAR TACHYCARDIA".  The underlying rhythm is sinus, with a remarkably long PR interval, and at least one episode of failure of the P wave to conduct, making "second-degree AV block, Type II" a possibility. It is difficult to thoroughly evaluate the underlying rhythm because it is not seen very often in this ECG. The rate of the underlying P waves is about 67 bpm.  The PR interval is .40 seconds (400 ms).  The "normal" QRS complexes are slightly widened, at about .10 sec (100 ms), which is typical of Type II AVB.  The ventricular QRS complexes are wide at .16 sec. (160 ms)

To assist you in using this tracing for teaching, we have also supplied a "marked up" version.  The P waves, both visible and hidden, are marked with red lines. The PR intervals are shown in the Lead V1 rhythm strip in green.  And the QRS complexes are numbered.  QRS complexes numbered 2, 3, 6, and 12 are sinus. The P wave AFTER QRS #5 is non-conducted.

To review the differentiation of ventricular tachycardia from supraventricular tachycardia with aberrant conduction, go HERE.

Dawn's picture

Ventricular Tachycardia

Submitted by Dawn on Thu, 03/19/2015 - 14:42

This wide-complex tachycardia is ventricular tachycardia.  Along with the wide QRS and the fast rate, features which favor a diagnosis of VT over BBB include:  backwards (extreme right) QRS axis, negative QRS in V6, and an apparently monophasic QRS in V1, as opposed to the rSR' pattern of right bundle branch block. 
Remember, ALL wide-QRS tachycardias should be treated as V Tach until proven otherwise, as it is a life-threatening arrhythmia.  Factors which lower cardiac output during V Tach include:  Fast rate, wide QRS, and lack of P wave preceding the QRS.  The sudden severe lowering of perfusion that usually accompanies V Tach can lead to rapid deterioraton and ventricular fibrillation.

For discussions by Jason Roediger (ECG GURU extroidonairre) on recognizing ventricular tachycardia, go to this LINK, and this LINK.

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