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Dr A Röschl's picture

Long QT Syndrome,Look Closely and Do Not Trust the ECG-Computer

Submitted by Dr A Röschl on Wed, 07/26/2023 - 06:36

ST-elevation V2/V3, why? The patient never had chest pain, echocardiography inconspicious. History of several syncopal episodes. But, there is something wrong with the ECG. We observe a sinus rhythm ECG, at first glance, there are ST-elevations in leads V2-V4. No ST-depressions are visible. Upon closer examination, a prominent T-wave is noted, starting immediately after the QRS complex. The ECG computer erroneously indicates a significantly shortened QT and QTc interval.

Dawn's picture

ECG Basics: Torsades de Pointes

Submitted by Dawn on Sat, 07/13/2013 - 12:30

Torsades de pointes, or polymorphic ventricular tachycardia, is a ventricular tachycardia precipitated by and associated with long QT Syndrome.  Long QT Syndrome can be congenital or acquired.  Torsades is life-threatening, and can be made worse by many drugs, including some of the drugs used to treat VT.  The rate is usually 150 - 250 / min. and the appearance is of a wide-complex tachycardia with QRS morphology changes.  In some leads, it will appear as if it is "twisting" around the isoelectric line, giving it the French name, Torsades de pointes, a ballet term meaning twisting of the points.  For a thorough discussion of Torsades, check this LINK.

Dawn's picture

Third-degree AV Block and Junctional Escape Rhythm With Right Bundle Branch Block and Prolonged QTc Interval

Submitted by Dawn on Sat, 01/26/2013 - 13:48

This ECG is from a 70 year old woman for which we have, unfortunately, no clinical information.  It shows a sinus rhythm with a rate of about 72 bpm (NSR) with AV dissociation caused by third-degree heart block.  The escape rhythm is junctional at a rate of 38 bpm.  There appears to be a right bundle branch block, based on the QRS duration of 132 ms, and a wide S wave in Leads I and V6.  The precordial leads do not show the usual RBBB pattern of rSR' in V1 and V2, and the r wave progression is poor (non-existent).  This is felt to be due to poor lead placement (a good teaching point).  Of interest, the ECG machine has reported a "severe right axis deviation" based on the tall upright R wave in aVR and the deep S in avF.  In RBBB, the first part of the QRS represents left ventricular depolarization, and the terminal wave represents the delayed right ventricle.  In effect, the two ventricles have their own electrical axes, which we can see because the ventricles are not depolarizing simultaneously.  The axis of the LV appears to be normal in this tracing.

In addition to the above, this patient has a very prolonged QT interval.  The QT is longer in bradycardic rhythms, but when corrected to a standard of 60 bpm (QTc), this patient's QT interval is still prolonged at QTc: 552 ms.  Without clinical data, we cannot speculate  as to why this patient's QTc is prolonged, but it can be a very dangerous situation.  Follow the links for more information on QT prolongation and Torsades de Pointes and Long QT Syndrome.

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