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V Tach

Ventricular Tachycardia

Sat, 11/24/2012 - 15:52 -- Dawn

This is a good example of ventricular tachycardia with PRECORDIAL CONCORDANCE.  The QRS complexes in the chest, or precordial, leads all point downward.  When the precordial leads are all  negative or all positive in a wide-complex tachycardia, there is virtually a 100% chance that the WCT is ventricular tachycardia.  This ECG shows many characteristics of VT, including the extreme "backwards" axis:  aVR is positive and II, III, and aVF are negative.  Lead I is almost equiphasic.  Also, the lack of a clear BBB pattern and a negative V6 are strongly suggestive of VT.  REMEMBER:  In the treatment of wide-complex tachycardia, the rhythm should be considered VT unless proven otherwise.  This is especially true in unstable patients, patients over 50 years old, and patients with known heart disease.

INSTRUCTORS' NOTE:  We purposely left the machine interpretation on this week's ECG of the Week.  How many errors did the machine make?  This might be a good teaching point for students of all levels.

 

Ventricular Tachycardia

Wed, 09/12/2012 - 00:00 -- Dawn

A 66 year old man is complaining of palpitations and chest pain which radiated to his left arm and neck, which lasted 20 minutes, then went away.  Paramedics found him in V Tach.  His BP was 120/80 and his pulse 120/min. He converted to a narrow-complex rhythm while being given amiodarone, but became nauseated.  He returned to V Tach, and his symptoms disappeared.  This patient had an implanted defibrillator, which never went off.  How do we know this is V Tach?

First, ALWAYS consider any wide-complex tachycardia to be VT unless you have proof that it is not.  When symptoms include chest pain, it can be especially dangerous to miss the diagnosis of VT.  Remember, some VT can be asymtomatic, even for prolonged periods of time.

ECG signs that this is VT include: QRS is extremely wide (>.14 sec), no P waves associated with the QRS complexes, negative complexes in V4, V5 and V6.  In fact, this patient has negative "precordial concordance" - all the chest leads are negative. This is a strong sign of VT.  The wide little r wave in V1, greater than .04 sec (one small block) is a strong indicator of VT, as is the delayed nadir of the S waves in V1 through V3 (the slope of the S wave is not steep, indicating a long time to depolarize the ventricles).

For more about V Tach criteria, browse this site and visit the ECG blogs on the Favorites page.  It is a favorite topic among ECG experts.

 

AV Sequential Pacing to Ventricular Tachycardia

Wed, 08/01/2012 - 13:01 -- Dawn

This is an interesting ECG for showing students AV sequential pacing and also ventricular tachycardia.  The unusual thing about this ECG is that the V Tach starts at the time the machine begins recording the precordial leads.  This particular ECG machine shows a slight "gap" at the lead change, so we don't see the actual start of the V Tach.  Both rhythms have wide QRS complexes. The pacemaker is pacing the right ventricle, so you will see a wide QRS with a leftward axis, as the impulse spreads up and leftward toward the left ventricle.   The V Tach portion is, of course, limited to the precordial leads, so we cannot plot the frontal plane axis.  But, it meets many of the accepted criteria for ventricular tachycardia, including:  very wide QRS, negative QRS in Lead V6, absence of RBBB or LBBB pattern.   For more on recognizing V Tach in a WCT, go to Ask the Expert at this LINK.    

This is also a very good example of how the interpretation by the machine can be wrong.  Always read the ECG yourself!

Wide Complex Tachycardia: V Tach

Sat, 06/02/2012 - 16:02 -- Dawn

This wide complex tachycardia occurred in a 91 year old man with a history of atrial fibrillation. He complained of "fluttering" in his chest, and denied chest pain or other problems.  While the paramedic attempted to start an I.V., he spontaneously converted to atrial fibrillation with left BBB, and PVCs.  Once he converted, his symptoms abated.  Remember, all wide complex tachycardias (WCT) should be treated as V Tach in the field, as this is by far the most common WTC and the most dangerous.

Some of the ECG clues that this WTC is ventricular tachycardia are:

* Monophasic upright QRS in V1  (does not have RBBB pattern of rsR')

* Extreme left axis deviation (II, III, and aVF are negative, I, aVL, and aVR are poisitive)

* V6 is negative

 

For a more thorough discussion of the ECG signs of V Tach, go to Jason Roediger's Ask the Expert page discussion on the topic:

http://www.ekgguru.com/node/157

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