While a rhythmOften refers to a discernible pattern in time or distance between QRS complexes and/or P waves. as a whole may be irregular, segments may be regular. These regular periods are often referred to as the underlying rhythm. Apply the three step method to the underlying rhythm first. When naming a rhythm, the underlying rhythm is identified before any irregular rhythm components.
Regular rhythms can almost always be quickly identified with just steps #2 (Is the QRS narrow or wide?) and #3 (Check the P wavesA wave generated from the depolarization of the atria; the P wave is upright when originating from the SA node. The P wave represents the depolarization of the right and left atria. The P wave begins with the first deviation...). Simple, basic and fast. These rhythms would include sinus rhythms, atrial rhythms, junctional rhythmsA cardiac rhythm that occurs as a backup pacemaker when the sinus node fails to initiate an impulse; the junction typically fires at 40-60/minute; the P wave is either absent or inverted. A cardiac rhythm is usually named first by... and ventricular rhythms of varying rates. The irregular rhythms – those with pauses, extra beats or have a chaotic patternPattern refers to the repeating components of an ECG rhythm in a predicative order. An ECG rhythm that is initiated by one of several intrinsic pacemaker sites of a heart will often generate a regular, even rhythm pattern. This can... – often demand closer inspection.
Checking for a regular rhythm patternAn ECG rhythm that is initiated by one of several intrinsic pacemaker sites of a heart will often generate a regular, even rhythm pattern. This can also be referred to as a regularly regular rhythm. For regular rhythms, sometimes the... simply involves determining whether the R-R intervalThe distance between the top of the R waves. Figure 4.15 The Normal Q Wave and QT Interval Figure 4.15 illustrates the Q wave, QT interval and the R-R interval. A normal QT interval should be less than half the... is consistent. This often can be accomplished with a quick visual snapshot of the rhythm. Are the QRS complexes evenly spaced?
Irregular rhythms should be printed on a rhythm strip of six seconds or longer. First, try to identify any periods of regularity. While the rhythm as a whole may be irregular, segments may be regular. These regular periods are often referred to as the underlying rhythm. Apply the three step method to the underlying rhythm first. When naming a rhythm, the underlying rhythm is identified before any irregular rhythm components.
Next study the segments of the rhythm that stand out as different. This may be early beats, periods where QRS complexes are absent, or other inconsistencies. Apply the 3-step method to these segments.
An example may help clarify this process. In Figure 5.5, the rhythm as a whole is not regular. The underlying rhythm runs through the middle of this rhythm strip. First apply the 3 step method to the underlying rhythm. Using the Rule of 300sThe Rule of 300s (also known as the triplicate method) is useful for measuring heart rate over shorter periods (less than 3 seconds) or for calculating heart rates of rapid tachycardias. This method is quick but not quite as accurate..., the rateHeart Rate; calculated by counting the number of QRS complexes in six seconds and multiplying by 10; rate is also determined by measuring the number of large squares between two R waves; i.e. –1 large square = heart rate of 300/minute. is somewhere around 75-100/minute. The QRS complexThe electrical representation of ventricular depolarization; the atrial repolarization is also a part of the QRS. ECG interpretation relies heavily on the QRS complex. The QRS complex represents the depolarization of the ventricles. The repolarization of the atria is also... is narrow. The impulse originates above the ventriclesThe larger chambers of the heart (3 times the volume and muscle thickness than the atria), responsible for the pumping of blood to the lungs and the rest of the body.. Where? The P waves are upright, a sign of a sinus focus. The underlying rhythm is a sinus rhythmAlso known as regular sinus rhythm or sinus rhythm, this cardiac rhythm is not a dysrhythmia; sinus rhythm originates in the sinoatrial (SA) node with a rate of 60-100/minute; P waves are upright in most leads and the QRS is....
The faster segmentA line between waves. Segments measure time between waves (waves are not included in a segment). While waves are fairly self-explanatory, intervals measure time from the start of one wave to the start of another wave (an interval includes at... on the right of this six second strip requires a second pass of the three step method. The rate is fast at about 210/minute. The QRS complexes are wide with no visible P waves. This is most likely a run of ventricular tachycardiaNon-sustained episodes of ventricular tachycardia (runs of VT) - consisting of 3 or more consecutive PVCs - can also be called bursts or salvos of ventricular tachycardia. A patient often senses a period of syncope during these episodes. Runs of....
An interpretation of this rhythm begins with the underlying rhythm followed by a description of any remaining rhythm features. You would call this rhythm a sinus rhythm with a runA sudden group of 3 or more ectopic beats or complexes (also called a burst or a salvo). 1. Six Second ECG Guidebook (2012), T Barill, p. 204 of ventricular tachycardiaIs a cardiac rhythm characterized by rapidly occurring wide QRS complexes with absent or infrequent P waves evident; the absence of atrial kick, the lack of filling time, and the tendency for ventricular tachycardia to change to ventricular fibrillation makes....
When rhythms have abnormal components that throw off the pattern of the rhythm, look for the parts of the rhythm that have a narrow QRS AND maintain a pattern. The age old task of picking out the “parts that are not the same”, as the Sesame Street jingle goes, helps establish what is the main rhythm and what is not. First identify the normal – or underlying – rhythm using the three step method. Then apply the three step method again to any of the remaining waveforms.
Occasionally, the entire rhythm is chaotic, devoid of any pattern. This chaotic nature is typical of atrial fibrillationOne of the most common dysrhythmias, the atria have a host of sites that are concurrently firing at a combined rate of 350-600/minute; since the junction allows maximum 240 impulses through per minute, the result is a chaotic rhythm most... and ventricular fibrillationA chaotic unorganized cardiac rhythm with several firing regions within the ventricles; the result is uncoordinated ventricular activity and NO cardiac output – a lethal dysrhythmia; fine ventricular fibrillation defines an amplitude less than 3 mm; coarse ventricular fibrillation has.... Use the three step method to determine where the impulse initiates. At this point, a differential of possible rhythms is useful. An even closer inspection of the rhythm is often required.
Knowledge of select rhythms that fall outside the normal spectrum will prepare you for this eventuality. These special rhythms are not numerous, nor are they particularly difficult to interpret. Give the 3-step method a try with a few practice rhythms. You may find that rhythm interpretation can be fast and quite simple.
Note the narrow, regular QRS complexes in the middle of this rhythm strip. Sinus rhythm is the underlying normal rhythm. The brief run of wide QRS complexes (ventricular tachycardiaA cardiac rhythm with a rate above 100/minute; for example, if the impulse originates from the atria with a rate of 160/minute, the rhythm is called an atrial tachycardia. A cardiac rhythm is usually named first by the location of...) stands out from the underlying rhythm. First name the underlying rhythm and finish with a description of any abnormal rhythm components. If we ignore the first complexA collection of waveforms (i.e. QRS complex and the ECG complex). 1. Six Second ECG Guidebook (2012), T Barill, p. 194 for now, the rhythm in Figure 5.5 then would be identified as a sinus rhythm with a run of ventricular tachycardia.
1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 113-114