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Narrow-complex Tachycardia In An Infant

Submitted by Dawn on Tue, 10/26/2021 - 14:20

The patient:  This ECG was obtained from a two-month-old girl who was a patient in the Emergency Department.  She had a fever due to a respiratory infection and was dehydrated. She was alert, active, and irritable.

The ECG:  There is a narrow-complex tachycardia at a rate of 194 bpm.  This is faster than the normal range for a two-month-old, which is about 80-160 bpm.  The intervals are all within normal range.  The frontal plane axis, at 145 degrees, is rightward, which is normal for this age. There are prominent, narrow Q waves in the inferior wall leads (II, III, and aVF) and in the left lateral leads (V4, V5, and V6).  There are no Q waves in the high lateral leads (I and aVL).  This is a normal pattern for this age group.   www.sciencedirect.com/science/article/pii/B9781416037743100280

The evaluation of this ECG must be preceded by a thorough evaluation of the patient.  SINUS TACHYCARDIA would be expected in the setting of fever, dehydration, hypoxia, pain or other discomfort. Should the rate fail to gradually return to a normal range after treatment, we would have to consider a reentrant supraventricular tachycardia. Reentrant tachycardias have a SUDDEN ONSET and SUDDEN TERMINATION.

Unfortunately, we do not have follow up on the patient.

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Sinus Tachycardia

Submitted by Dawn on Wed, 10/09/2019 - 20:42

This ECG is from a collection of tracings that, sadly, have no patient information.  It is interesting nonetheless, and we would love to hear your thoughts on it.

ECG Findings:  The rhythm is sinus tachycardia, at a rate of 120 bpm.  The QRS is narrow at .08 seconds (82 ms).  While the PR interval is normal, at .14 seconds (140 ms), the PR segment is very short. The PR segment is the line between the end of the P wave to the beginning of the QRS complex.  This can indicate the presence of an accessory pathway that bypasses the AV node, or of faster conduction within the AV node. The P waves in the inferior leads II, III, and aVF barely meet voltage criteria for right atrial enlargement,  but the P waves in V1 do not have the usual prominent positive deflection one would expect with RAE.  Even with the short PR segment, the segment appears to be elevated in the inferior leads, without any reciprocal PR depression.  The PR segment is where atrial repolarization occurs (the atrial “T” wave). There are many conditions that can elevate or depress PR segments, and without a patient story here, we can’t guess at the cause.  If you are an instructor, this would be a good ECG to illustrate why we use the TP segment to determine the “isoelectric line”, rather than the PR segment.

The inferior ST segments are very flat, which is not normal, while the rest of the ST segments display the normal concave up “smile” shape.  Serial ECGs would no doubt be helpful here, to recognize changes in the ST segments.

Bottom Line:  It would be much easier to make a determination about the causes of these subtle changes if we had patient information.  However, this ECG is still valuable as an exercise in measuring intervals, and as an example of short PR segment. It is also a good example of a fairly fast sinus tachycardia.  We would love to hear our visitors’ thoughts on this tracing.

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Tachycardia In An Unresponsive Patient

Submitted by Dawn on Tue, 08/20/2019 - 20:48

 The Patient     This ECG was obtained from a 28-year-old woman who was found in her home, unresponsive.  She was hypotensive at 99/35.  No one was available to provide information about past medical history or the onset of this event.

Before you read my comments, pause to look at the ECG and see what YOU think.  We would welcome comments below from all our members!

The ECG     This ECG is quite challenging, as it illustrates the helpfulness of ECG changes in patient diagnosis, and also points out how important clinical correlation is when the ECG suggests multiple different problems. Forgive me in advance, but there is a lot to say about this ECG.

The heart rate is 148 bpm, and the rhythm is regular, although not perfectly. P waves are not seen, even though the ECG machine gives a P wave axis and PR interval measurement. The rate is fast enough to bury the P waves in the preceding T waves, especially if there is first-degree AV block. Differential dx: sinus tachycardia, PSVT, atrial flutter. The very slight irregularity points more towards sinus tachycardia.  The rate of nearly 150 suggests atrial flutter with 2:1 conduction, but the only lead that looks remotely like it has flutter waves is V2. The lack of an onset or offset of the rhythm makes it difficult to diagnose PSVT with any certainty.

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Syncope and tachycardia

Submitted by Dawn on Sun, 01/13/2019 - 22:32

The patient:  This ECG is taken from a 55-year-old man whose wife called 911 because he had a syncopal episode.  When the paramedics arrived, he was conscious and alert, and denied any symptoms.  He gave a history of "cardiac", diabetes, and opiate abuse.  We do not know the nature of his cardiac history or his medications.  

It is difficult to pinpoint a definite diagnosis with this lack of information and a clearly abnormal ECG.  We will limit our discussion to listing the abnormalities seen:

The ECG rhythm:  There is a fast, regular rhythm that is supraventricular in origin (there are P waves).  When a supraventricular rhythm has a rate of about 150 per minute, we should ALWAYS consider ATRIAL FLUTTER WITH 2:1 CONDUCTION.  Atrial flutter produces P waves (flutter waves) at approximately 250-350 per minute.  The normal AV node is able to conduct half of these, at a rate of about 150 per minute. Atrial flutter with 2:1 conduction is the most common presentation of new-onset atrial flutter.  It is often missed by people who expect to see several flutter waves in a row, producing the "sawtooth pattern".  That being said, atrial flutter is usually discernable in at least a few leads if it is present.  We do not see any signs of flutter waves in this ECG.

That leaves us with a differential diagnosis of sinus tachycardia vs. one of the regular supraventricular tachycardias like reentrant tachycardias or atrial tachycardia.  Sinus tachycardia can be recognized by several features. If we are fortunate enough to witness the onset or offset of the fast rhythm, will will recognize sinus tachycardia by a "warm up" or gradual speeding up of the rate, and a "cool down", or gradual slowing.  On the other hand, SVTs often have abrupt onset and offset.  Sinus tachycardia often has a very obvious cause, such as hypovolemia, fever, pain, anxiety, vigorous exercise, or hypoxia.  Sinus tachycardia usually has a distinct, upright P wave in Lead II, and a clearly-seen, often negative, P wave in Lead V1.  This ECG does not show the onset of the tachycardia, and is not long enough to evaluate for rate changes. Lead II appears to have upright P waves on the downslope of the previous T waves. V1 has deeply negative P waves, and V4 has the most clearly-seen P waves.  Without being positive, this looks more like sinus tachycardia than a reentrant tachycardia.  It would help to know more about the patient's condition.

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Left Bundle Branch Block

Submitted by Dawn on Tue, 01/17/2017 - 18:36

This ECG was taken from an unknown patient.  It shows sinus tachycardia with left bundle branch block. The ECG criteria for left bundle branch block are: 

* Wide QRS (.12 seconds or greater)

* Negative QRS deflection in V1

* Positive QRS in Leads I and V6 

* Supraventricular rhythm

In addition to these criteria, left bundle branch block will cause repolarization abnormalities.  This is because depolarization is altered through the left ventricle, which causes repolarization to also be altered.  Instead of the electrical impulse traveling down the left bundle branch to depolarize the left ventricle, it depolarizes the right ventricle first, then spreads cell-to-cell across the larger left ventricle. The ST and T wave changes caused by left bundle branch block are normally “discordant”.  That is, the ST segment will be elevated in leads with negative QRS complexes, and depressed in leads with positive QRS complexes.  This elevation and depression of the ST segment may “imitate” the changes caused by acute myocardial infarction.  They may also work to conceal M.I. changes, as we may not recognize  STEMI as we attribute the ST changes to the left bundle branch block itself. 

For more on determining the presence of acute M.I. when the patient has left bundle branch block, check out these links:  ECG Guru, LBBB with AMI; Life in the Fast Lane, Sgarbossa Criteria; EMS 12-Lead, Sgarbossa Criteria;  Dr. Smith's Modified Sgarbossa Criteria. 

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Teaching Series - Tachycardia and Left Anterior Fascicular Block

Submitted by Dawn on Sat, 10/15/2016 - 15:48

This series of three ECGs is from a 60-year-old man who was brought to the Emergency Department after being involved in a motor vehicle accident.  No injuries were found, but the patient was severely intoxicated by alcohol consumption.  He was conscious but agitated. 

ECG NO. 1     15:07:23

The first ECG was taken by fire-rescue personnel at the scene of the accident. His hemodynamic status was stable, and the rate was not addressed in the field. ECG No. 1 shows a supraventricular rhythm at 161 bpm, with a narrow QRS and P waves visible before each QRS. 

A notable feature of this ECG are the left axis deviation, by default diagnosed at left anterior hemiblock (left anterior fascicular block).  The .10 second QRS width is typical of LAHB, as is the rS pattern in Lead III.

Also  noted is the unusual R wave progression in the precordial leads.  The R waves are prominent in V2, and then fail to progress across the precordium, and the S waves persist. This is probably due to the hemiblock.  We do not know this patient’s medical history, except that he self-described as an “alcoholic”.  LAFB can be associated with coronary artery disease. 

ECG NO. 2      15:20:38

Now being evaluated in the Emergency Dept., we see the patient's heart rate is 163 bpm.  Some variability in the rate was noted with patient agitation and activity, so it was determined that the rhythm was probably sinus tachycardia.  There were no other significant changes in the ECG from the first one.  Unfortunately, we no longer have access to lab results, so we do not know his electrolyte or hydration status.  Labs confirmed ETOH intoxication. 

ECG NO. 3   15:43:26

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ECG Basics: Sinus Tachycardia vs. PSVT

Submitted by Dawn on Thu, 04/21/2016 - 00:13

Narrow-complex tachycardias can be very confusing to students of basic-level ECG.  There are very many rhythms that fall into the broad category of narrow-complex tachycardia.  We usually further divide them into sinus tachycardia and other "supraventricular tachycardias".  The basic student will want to make this distinction, as well as be able to differentiate atrial fib and atrial flutter from the other SVTs.  The more advanced student will want to go into more detail about which mechanism for supraventricular tachycardia is present.

Just the basics, please.   When the tachycardia is regular, it is most important to determine whether it is a SINUS TACHYCARDIA or a SUPRAVENTRICULAR TACHYCARDIA.  (Yes, we are aware that sinus rhythms are supraventricular, but the term "supraventricular tachycardia" or "SVT" is usually reserved for the fast, regular rhythms that are not sinus.)  So, what clues will be most helpful to our beginner students?

Rate    SVTs tend to be faster than sinus tachycardia.  More importantly, they are fast regardless of the patient's situation.  Sinus tachycardia almost always is reacting to the patient's situation.  For instance, a 22-year-old woman resting in a chair with a heart rate of 150 is likely to have an SVT.  A 22-year-old woman who is running in a 10 k marathon race and has a heart rate of 160 is responding appropriately to an increased need for oxygen and nutrients to her cells. Sinus tachycardia will ususally be 160 or less, and have an obvious reason for being, such as fever, pain, anxiety, exercise, hypovolemia, hypoxia, or drugs.  Unfortunately, many beginning students are told that any narrow-complex tachycardia with a rate of 150 or less is sinus, and over 150 is SVT. While they may be right most of the time, or on the written test they are about to take, this rule should not be applied in "real life".  Sinus rhythms can go over 150, and SVTs can be slower than 150.  So, what other clues should we be teaching beginners?

Consider the clinical situation    Look for an obvious cause for sinus tachycardia.  If none is found, strongly consider SVT.  Remember that pediatric patients have faster heart rates, especially infants.  If the strip is on a test, with no clinical information, consider these:

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ECG Basics: Sinus Tachycardia, Peaked T Waves, and Baseline Artifact

Submitted by Dawn on Sun, 03/13/2016 - 21:45

This strip offers several good teaching opportunities.  If it were a 12-lead ECG, no doubt it would be a bonanza!  First, there is sinus tachycardia at a rate of about 138 per minute.  The P waves are all alike and regular.  The T waves are tall and narrow, with a sharp peak.  This is often a transient sign of hyperkalemia, and should be investigated with serum electrolyte tests and with a 12-lead ECG.  In addition, the baseline shows a wandering type of artifact.  This is due to the patient's deep breathing, and the fact that the arm electrodes were placed on the chest.  This patient was a diabetic in ketoacidosis with hyperkalemia. 

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Inverted T waves in Lateral Wall

Submitted by Dawn on Tue, 11/10/2015 - 20:45

This ECG was obtained from a 49-year-old man who was a patient in an Emergency Dept.  We do not know his presenting complaint, only that he had a history of insulin-dependent diabetes mellitus (IDDM).  It was noted by the donor of the ECG that the patient had no chest pain, no shortness of breath, and no other cardiac symptoms.  We do not know his hydration or electrolyte status.  There are quite a few interesting abnormalities on this ECG, and the exact interpretation would, of course, depend upon the patient's clinical status.  It would definitely help to be there!

First, we note a sinus tachycardia at a rate of 118 bpm.  This could be due to very many causes, including but not limited to:  dehydration, pain, anxiety, high or low blood glucose, fever, or CHF.  The PR and QT intervals are within normal limits.  The QRS complexes are narrow.  The axis is normal at 0 degrees.  The QRS voltage in the lateral leads is on the high side of normal, but we do not know this patient's body type.  Voltage as read by the ECG can be influenced by a thin chest (making voltage look larger) or a large chest (making voltage lower).

There are T wave abnormalities in the lateral leads:  I, aVL, V5 and V6.  The T waves are inverted, which can have many meanings.  However, when inverted T waves are in the lateral leads, as opposed to the inferior or right chest leads, it is often a sign of ischemia.  The flat, horizontal ST segments can also signify coronary artery disease (CAD).  This patient denied cardiac symptoms, but his age and history of IDDM make it probably that CAD is a factor.  The leads with T wave inversion also have a small amount of ST segment depression.  The right precordial leads, V1 and V2, have a small amount of ST elevation,  This possibly represents a reciprocal change to the ST depression in V5 and V6.

Because we are not at the bedside of this patient, there are many details we do not know.  But these inverted T waves could be ischemic T waves, and this requires that the patient be further evaluated.

As always, we welcome comments, as this ECG probably has more to say!

 

REFERENCES:  Dr. Ken Grauer,  Life In The Fast Lane, World Journal of Cardiology 

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ECG Basics: Sinus Tachycardia

Submitted by Dawn on Wed, 06/10/2015 - 20:53

This is a good teaching strip on many levels.  At the BASIC level, we see a strip that clearly meets all the criteria for sinus tachycardia:  a regular rhythm over 100/min. with P waves that look normal and all look alike.  The rate is 110 per minute.  The PR interval is just at the upper limits of normal at .20 second, or 200 ms.  The QRS complex is within normal limits, but slightly wide at .10 seconds.

This strip is good for teaching rate determination by several different methods.  It is helpful that QRS complexes 1, 5, and 10 fall on the dark lines of the paper.

This is a Lead II rhythm strip, and it is helpful to show students that not ALL Lead II strips produce an upright QRS complex.  Of course, correct lead placement should be confirmed.  In this particular case, the patient had suffered an anterior - septal wall M.I., and has a left anterior hemiblock, also called left anterior fascicular block.  This shifts the frontal plane axis to the left, causing Lead II to have a negative QRS.  Axis can't be accurately determined from one lead, but axis shift explains the negative QRS in this strip.

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