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Dawn's picture

Instructors' Collection ECG: Wide Complex Tachycardia

The Patient:   A 78-year-old woman called emergency responders because she had palpitations. She was alert and oriented.  Her BP was reported as being “stable”.  We do not have information about her past medical history.  We will update this post if we receive information about her outcome. 

ECG Number 1, 11:57 a.m.:  There is a wide-complex tachycardia at a rate of about 230 bpm.  The QRS is .15 seconds (150 ms).  The QRS frontal plane axis is leftward. P waves are not readily seen, but the computer gives a P axis and PRI.  The PRI given is taken from Lead II, which, along with V5, does have P waves. In the other leads, the P waves are buried in preceding T waves.  This photo shows an ECG that is not lying flat, so it is difficult to line up the complexes.  Normally, it helps to look at the leads above or below to determine where waves begin and end, as all three channels are run simultaneously. The QRS complexes have a “typical” left bundle branch block morphology, with an rS complex in V1 and a monophasic R wave in Leads I and V6.  The T waves are “discordant”, they are in the opposite direction from the QRS complexes, which is typical of LBBB. 

ECG Number 2, 12:05 p.m.:   This is a rhythm strip recording a synchronized shock at 100 joules, resulting in conversion of the WCT to a narrow complex, irregular rhythm.  It appears that there is a P wave before every narrow QRS, but artifact prevents proper evaluation. 

Dr A Röschl's picture

Atrial Fibrillation With Rate-related Left Bundle Branch Block

For a better overview, the leads aVL and V2-V4 are not shown in this ECG. The basic rhythm is atrial fibrillation (no P waves or flutter waves visible, but fibrillation waves). When the conduction rate drops, the QRS complexes are narrow. Faster conduction results in wide QRS complexes with LBBB morphology. This is an example of phase 3 (acceleration dependant) LBBB.

Dr A Röschl's picture

Left Bundle Branch Block

Why is this a left bundle branch block? We see a SR with broad QRS complexes (more than 120 ms). These are positive in the leftward leads I and aVL and in V5 and V6. In the more rightward leads III, aVR, and V1-V3, the QRS complexes are predominantly negative with deep S waves. This is a typical LBBB pattern.

Dr A Röschl's picture

Second-degree AV Block with Left Bundle Branch Block & Lead Reversal

This ECG shows second-degree AV block, Mobitz Type II and an interventricular conduction delay, probably left bundle branch block. The QRS width is about 130 ms, or .13 seconds.

Dawn's picture

Inferior Wall M.I. In A Patient With Left Bundle Branch Block

The Patient:    A 64-year-old man complaining of chest pain and shortness of breath for 20 minutes.  Long-standing history of triple vessel disease, severe aortic stenosis, hypertension, thrombocytopenia.  Meds unknown.  He was not considered to be a candidate for valve surgery.

 

The ECG: There is normal sinus rhythm with a rate of 90 bpm.  P waves are not visualized well in all leads, so remember that the three channels of this ECG are run simultaneously.  If you see a P wave in Leads I and II, they are also present in Lead III.  The PR interval is WNL.

 

The QRS complexes are wide, at .122 seconds (122 ms).  The criteria for left bundle branch block are met. (Supraventricular rhythm, wide QRS, upright QRS in Leads I and V6, negative QRS in V1).  The frontal plane axis is within normal limits, but toward the right, at 87 degrees.  The QRS complexes transition at V4 from negative to positive, but Leads V1 – V3 have no initial r waves.  These are possibly pathological Q waves, likely from a past anterior-septal M.I.

 

Dawn's picture

Rate-related Left Bundle Branch Block

The patient:  This ECG is from an 87-year-old man who was transported to the Emergency Department by paramedics. His chief complaint, as reported by caregivers, was lethargy, fever, and a declining mental status.  He appeared tired and slightly confused, and was normotensive.

The ECG:  There are a rhythm strip with two leads, II and III, and also a standard 12-lead ECG. The RHYTHM STRIP shows a tachycardiac rhythm that slows very slightly toward the end.  The rate is around 107 bpm, with an R to R interval of approximately 543 ms in the earlier, regular portion.  There are regular P waves present, all followed by QRS complexes.  Most of the QRS complexes are normal width, but the 2nd, 5th, and 8th are slightly wide at 130 ms, or .13 seconds.

These wider QRS complexes represent aberrant conduction with LBBB occurring intermittently.  Aberrant conduction often occurs due to a faster heart rate, but the only clue here is the intermittent conduction disturbance seems to disappear when the rate slows very slightly.  It is hard to determine mechanism of aberrant conduction when we have only a ten-second rhythm strip.

The 12-LEAD ECG  has essentially the same rate and rhythm, except all the beats in the first ¾ of the ECG are conducted aberrantly, in a LEFT BUNDLE BRANCH BLOCK pattern.  This indicates that the LBB is refractory at this time.  Beat No. 15 is premature (PAC).  The pause after the PAC allows the left bundle branch to repolarize, conducting one single beat normally.

Dawn's picture

Left Bundle Branch Block

This ECG is taken from an elderly man with heart failure. 

The ECG   The first feature that might capture your attention is the wider-than-normal QRS complex, which is 160 ms (.16 seconds).  The rate is 58 bpm. We do not know the patient’s medications or baseline rate.  There are P waves present, and so the rhythm is SINUS BRADYCARDIA. The P waves are broad , > 110 ms in Lead II (red lines in close up) and bifid, with greater than 40 ms between the two peaks in Lead II (blue lines).  In V1, the P waves are biphasic, with the terminal negative portion greater than 40 ms duration (red lines). This meets the ECG criteria for LEFT ATRIAL ENLARGEMENT, or preferably, LEFT ATRIAL ABNORMALITY. (https://LITFL.com/left-atrial-enlargement-ecg-library/) ECG criteria are not highly accurate for detecting atrial enlargement, and abnormal findings should be confirmed by anatomic measurement. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2244611/).

The QRS complexes, as mentioned, are wide. Because there is sinus rhythm, we know the delay in conduction is due to interventricular conduction delay, and not to ventricular rhythm.  This ECG meets the criteria for LEFT BUNDLE BRANCH BLOCK. 

·        Supraventricular rhythm 

·        Wide QRS (>.12 seconds)

Dawn's picture

Wide Complex Tachycardia

The Patient   A 64-year-old woman has called 911 because she has chest discomfort radiating to her left arm, palpitations, weakness, and a headache.  She had a valve replacement (we do not know which valve) two weeks ago and has a healing incision over her sternum.  She is found sitting in a chair, pale, cool, and diaphoretic. Her blood pressure is 94/palp.  Her pulse rate is 196 bpm and weak. She is afebrile.

ECG #1   This ECG shows a wide-complex tachycardia at 196 bpm.  The QRS complexes are .132 seconds in duration, per the ECG machine. The rate is too fast to appreciate whether there are P waves present.  We did not see the onset of the tachycardia, but with a rate this fast and regular, it is most likely a reentrant rhythm, rather than sinus tachycardia.  An abrupt onset of the rhythm would point to a diagnosis of a reentrant rhythm, either ventricular tachycardia (VT) or paroxysmal supraventricular tachycardia (PSVT). 

There is an important rule in emergency medical care:  a wide-complex tachycardia should be treated as VT until and unless it is proven to be something else.  The most likely alternate interpretation is PSVT with aberrant conduction, which usually takes the form of left or right bundle branch block. Fortunately, the paramedics on this call have a protocol for treating WCT that includes electrical cardioversion for the unstable patient, and amiodarone for the stable patient.  This protocol serves both possibilities, VT and PSVT, well.  The patient’s perfusion status and BP made her borderline in this determination, but she was alert and oriented, so the paramedics opted for administering the amiodarone while they prepared to electrically cardiovert.

Dawn's picture

Wide Complex Tachycardia

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

Wide QRS Complex With First-degree AV Block

The Patient:  This ECG was taken from a 73-year-old man with a history of heart failure with preserved ejection fraction, severe left ventricular hypertrophy, Type II diabetes, and stage 4 chronic kidney disease.  He also suffered deep vein thrombosis and is on anticoagulation.  He has a recent diagnosis of IgA myeloma.  He presented with a complaint of nausea and vomiting and was found to have a worsening of acute kidney infection.  There was suspicion of renal and cardiac amyloidosis, but the patient refused biopsy to confirm this.  He was started on chemotherapy for multiple myeloma and will be followed as an outpatient.

The ECG:  The rhythm is sinus at around 60 bpm, although the rate varies a little at the beginning of the strip.  The QRS complex is wide at .12 seconds, or 120 ms., representing interventricular conduction delay (IVCD).  The PR interval is .32 seconds, or 320 ms. This constitutes first-degree AV block.  There is left axis deviation in the frontal plane and poor R wave progression in the horizontal plane.

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