Displaying 31 - 40 of 66
Dawn's picture

ECG Basics: Normal Sinus Rhythm With Premature Ventricular Contractions

Submitted by Dawn on Sat, 02/21/2015 - 17:22

This ECG shows an underlying rhythm of normal sinus rhythm at a rate of 80 / min.  There are two premature ventricular contractions (PVCs).  The sinus rhythm actually continues uninterrupted, causing a “compensatory pause”.  If you march out the P waves, you may even see hints of the hidden P waves in the ST segments of the PVCs.  The P waves that occur in the ST segments of the PVCs land in the refractory period of the ventricles, and so are unable to continue into the ventricles and cause a QRS. 

 

It is also permissible to call these beats “ventricular premature beats (VPBs)” or “ventricular premature complexes (VPCs)”.  

Dawn's picture

ECG Challenge: Grouped Beating - Double Tachycardia - ANSWER

Submitted by Dawn on Tue, 02/03/2015 - 19:06

This series of strips was donated by Arnel Carmona, and was taken from a patient admitted to the hospital for a urinary tract infection.  No other history is known.   On close examination of this rhythm what do we see?

Strip 1:   Narrow-complex tachycardia with NO apparent P waves.

Strip 2:   Some irregularity, with long regular groups and still NO P waves.

Strips 3 & 4:  Grouped beating.

Strip 5:   A narrow-complex rhythm that is approximately ½ the rate of Strip 1. 

When grouped beating is seen, one should always suspect Wenckebach conduction.  Wenckebach conduction (progressively longer conduction times through the A-V conduction system) can occur in rhythyms other than sinus rhythm.  Without P waves and PR intervals, GROUPED BEATING is our major clue to Wenckebach conduction. 

This patient has an underlying atrial fibrillation – hence no P waves.  Fine fibrillatory waves can be seen, but artifact can cause the same appearance.  So, why is there no irregular irregularity?  There is another rhythm at work here along with the atrial fibrillation.  Junctional tachycardia is seen in Strip 1.  When two tachycardias coexist, one from above the AV junction, and one from below, the rhythm can be called a “double tachycardia”.  This particular combination often happens in patients with digitalis toxicity. 

In some cases, a complete heart block at the level of the atrial conduction fibers or the AV node causes  two rhythms to operate independently.  Any supraventricular rhythm, including atrial fib, can occur with a complete heart block, in which case we would see an “escape” rhythm.  Escape rhythms are usually slow, either idiojunctional (40-60 bpm) or idioventricular (< 40 bpm).  

 Let’s look at each of the strips in detail.  We will begin with the hypothesis that this is atrial fibrillation with concurrent junctional tachycardia at around 150 bpm.  I will include laddergrams to illustrate my view of what is happening. 

Dawn's picture

ECG Challenge: Grouped Beating - Double Tachycardia

Submitted by Dawn on Sun, 01/25/2015 - 17:42

This very interesting set of strips was donated to the ECG Guru by Arnel Carmona, well-known to many of you as the Administrator of the blog, "ECG Rhythms" and the FB page by the same name.  He is a frequent contributer to the FB page, "EKG Club", and is an ECG Guru!  This set of strips was previously posted to his blog and to the EKG Club.  In case you haven't already seen it, we will withhold the interpretation for now to give everyone a chance to comment.  In one week, we will post the interpretation.

SEE THE INTERPRETATION AT THIS LINK

*********************************************************************************************

Dawn's picture

ECG Basics: Paroxysmal Supraventricular Tachycardia Treated With Adenosine

Submitted by Dawn on Sun, 12/28/2014 - 17:43

This series of ECG rhythm strips shows a paroxysmal supraventricular tachycardia successfully treated with adenosine.  The patient was complaining of a rapid heart rate and palpitations, but was hemodynamically stable.  It is not known whether any parasympathetic stimulation, such as a Valsalva maneuver or carotid sinus massage, was used initially.   

The first rhythm strip shows a PSVT, presumably AV nodal reentrant tachycardia, at a rate of about 215 per minute.  (We originally indicated a rate of 240 per minute, but this was a typo). Using the simplist method of determining rate, the six-second method, we see 21, but almost 22, QRS complexes in six seconds. Differential diagnosis would include sinus tachycardia, but this rate is too fast for sinus tach, especially in a resting patient.  Also, sinus tach would slow down as the patient is rested or made more comfortable, and this rate did not vary.  Also, when confronted with a supraventricular tachycardia, one should also consider atrial flutter and atrial fibrillation.  This is somewhat slow for atrial flutter with 1:1 conduction, and that rhythm is much more rare than AVNRT. It is too regular for atrial fibrillation.  So, we are left with the probable diagnosis of paroxysmal supraventricular tachycardia.  The “paroxysmal” part is presumed since AVNRT has an abrupt onset, and the patient’s symptoms started suddenly. 

The second rhythm strip shows what happened after adenosine was administered.  The patient received first a 6 mg dose, rapid IV push.  When that was not effective, he received 12 mg rapid IV push.  The rhythm strip is typical of the first minute or so after adenosine administration.  Adenosine can cause transient AV blocks, escape rhythms, and ectopic irritability.  The half-life of adenosine is only 6 seconds, so the dysrhythmias and uncomfortable symptoms are short-lived.  In this strip, we see frequent PVCs and runs of V tach.  

Dawn's picture

ECG Basics: Paroxysmal Supraventricular Tachycardia

Submitted by Dawn on Fri, 11/21/2014 - 21:07

This two-lead rhythm strip clearly shows the transition from normal sinus rhythm to a paroxysmal supraventricular rhythm.  In this case, the arrhythmia is AV nodal reentrant tachycardia, AVNRT.  The rate of the first rhythm, NSR, is around 75 per minute.  The fourth beat on the strip is a PAC which initiates the paroxysm of tachycardia lasting 12 beats.  The arrhythmia terminates spontaneously at that point.  The tachycardia rate is about 150/min.

The topic of supraventricular tachycardias can be a very complex one to teach.  For an excellent example of a concise lesson geared toward Primary Practice physicians, go to Dr. Grauer's VIDEO - Part III of his Arrhythmia series.

To cover the important points for the beginner-level student:

  *  It can be difficult to determine a rhythm is SVT if the rhythm is near 150 bpm and you DON'T see the beginning or end of the arrhythmia.  If the onset (or offset) is sudden, then this is not a sinus rhythm.  The sinus node speeds and slows more gradually - it doesn't change rates in one heartbeat.  This strip has an excellent view of BOTH the onset and the offset.

  *  The faster the rate, the more likely we are looking at a PSVT rather than sinus rhythm.  If a sinus tachycardia exists, we can almost ALWAYS see the reason for it in the patient's clinical situation.  We may see fever, dehydration, bleeding, fear, pain, exercise.  Therefore, a patient at rest with a rate of 150 would be suspect for PSVT.  A patient on a treadmill for 5 minutes would be considered to have a sinus rhythm.

  *  Any patient with a rate around 150 per minute should be evaluated for ATRIAL FLUTTER with 2:1 conduction.  Atrial flutter often conducts at that ratio, because a rate of 150 is fairly easy for the AV node to conduct, whereas the instrinsic rate of atrial flutter (250-350) is not.  A 12-lead ECG makes it easier to search for tell-tale flutter waves.

Dawn's picture

ECG Basics: Ventricular Fibrillation Converted With Defibrillation

Submitted by Dawn on Sat, 09/06/2014 - 20:48

A good example of ventricular fibrillation converted by electric defibrillation to what appears to be a sinus rhythm.  There is significant artifact in the post-conversion strip, but the last beat on the strip appears to have a P-QRS-T sequence.

Of course, V Fib presents without pulses, and must be defibrillated as soon as possible.  Best results are achieved by defibrillating a perfused heart, so if there is any delay from onset of V Fib, CPR should be performed to perfuse the heart prior to defibrillation.

Dawn's picture

ECG Basics: Atrial Flutter With 2:1 Conduction Ratio, Rhythm strip

Submitted by Dawn on Thu, 07/17/2014 - 15:40

One of the most frequently misdiagnosed rhythms, atrial flutter with 2:1 conduction often masquerades as sinus tach.  Sinus tach usually has an obvious cause, such as exercise, severe hypovolemia, or age less than 6 months.  Atrial flutter usually produces flutter waves (P waves) at a rate of 250 - 350 per minute.  Therefore, a 2:1 conduction ratio would result in a heart rate of about 125 - 175 bpm).  

Often, students are taught about atrial flutter using an electronic rhythm generator or a book with limited illustrations, and they become acustomed to seeing atrial flutter with 3:1 or 4:1 conduction.  The flutter waves are very easy to see in such a situation.  However, the AV node, if not affected by medication, is usually well able to conduct at a rate of 150 or more.  Therefore, the physiological block that protects us from extreme rates will keep the heart rate around 150 bpm in atrial flutter.

This is a single rhythm strip.  It can be VERY helpful to look at multiple leads to look for flutter waves.  See this week's Instructors' Collection ECG of the WEEK for the SAME patient's 12-Lead ECG.  Also, your students should be reminded that sinus rhythms, including sinus tach, tend to change rates based on the needs of the patient.  For example, as a patient is treated for his/her condition, the rate may improve by slowing.  Conversely, if the condition becomes worse, or the patient is stressed, the rate may increase.  Atrial flutter, like all re-entry tachycardias, tends to stay at a steady rate unless the conduction ratio changes.

Show your students that the flutter waves are CONTINUOUS.  That is, they don't pause for the QRS.  The second illustration shows the flutter waves highlighted, to aid in seeing the continuous line of flutter waves.

Dawn's picture

ECG Basics: Baseline Artifact

Submitted by Dawn on Thu, 07/10/2014 - 21:07

This rhythm strip shows normal sinus rhythm, slightly on the fast side of normal at 95 bpm.  The baseline undulates up and down with the movements of the patient's chest as she breathes.  One way to correct this problem on a monitor strip is to move the limb electrodes away from the chest and onto the limbs.

Dawn's picture

ECG Basics: 60-cycle Artifact

Submitted by Dawn on Mon, 06/09/2014 - 19:55

Here is a good example of 60-cycle interference artifact on a sinus rhythm strip.  The artifact is caused by electrical interference from a nearby electrical appliance. Modern monitors are able to filter interference out, but it is still occasionally seen.  Even though we can still discern P waves in this strip, and we can see that the rhythm is irregular, possibly sinus arrhythmia, the artifact prevents us from accurately evaluating the strip.  Every effort should be made to identify the offending device.  In "ECG Basics", we attempt to stay "basic", but if any of our Gurus would like to comment on this in a more technical fashion, it is welcome.

Dawn's picture

ECG Basics: Normal Sinus Rhythm

Submitted by Dawn on Mon, 05/19/2014 - 13:15

We try to remember to include some good old "Normal Sinus Rhythm" strips from time to time.  Teachers often have large collections of strange and unusual strips that their colleagues have saved for them.  But, then they find themselves resorting to electronic rhythm generators for samples of "normal".  Here is a strip from a healthy, 23-year-old woman showing NSR.  The rate is 65 bpm, QRS duration 76 ms, PRI 136 ms, QTc 410.  There are no abnormal ST segments or T wave changes.  There are very slight rate changes from beat to beat, and the P waves appear to change morphology a bit.  This can be due to the patient's breathing movements, and we would not delve too deeply into this in light of the fact that this is an ECG from an asymptomatic young ECG student.  Absolute precision would come from an generator, but rarely from a human being. This is a good strip to teach rate and interval determination.

Pages

All our content is FREE & COPYRIGHT FREE for non-commercial use

Please be courteous and leave any watermark or author attribution on content you reproduce.