Arrhythmia Recognition: The Art of Interpretation

A rhythm strip from lead 2 shows a small peak of the R wave, a sharp dip of the S wave, a broad peak of the T wave, and flat f waves leading to the R wave. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: Atrial: None Ventricular: About 90 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Normal
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

ECG 20-1 shows the typical changes of atrial fibrillation: lack of P waves and an irregularly irregular ventricular response. Note that the f waves are present but they are very fine, almost a straight line in appearance. Perhaps the f waves would be more easily demonstrated in another lead. The QRS complexes are normal in appearance and narrow, well within the normal limits for the QRS interval. The ST segments and T waves all appear normal.

ECG 20-2

A rhythm strip from lead 2 shows sharp peaks of varying heights occurring at irregular intervals, followed by ST segments with scooping appearance. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: Atrial: None Ventricular: About 90 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Normal
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

ECG 20-2 shows an irregularly irregular rhythm and no visible P waves. This is another typical example of atrial fibrillation. Some slight morphologic differences between the QRS complexes are frequently seen in Afib. The ST segments are depressed and have some scooping visible. However, they are not your typical digitalis-effect scooping ST segments. Ischemia is another dangerous possibility. Clinical correlation is indicated.

ECG 20-3

A rhythm strip from lead 2 shows small peaks of the R waves, small dips of the S waves, and mild fluctuations of the f waves. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: Atrial: None Ventricular: About 80 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Wide
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

ECG 20-3 shows a more defined f-wave pattern and no obvious or recurrent changes that could be interpreted as P waves. The ventricular rhythm is irregularly irregular, making this an atrial fibrillation rhythm. What about the ventricular response—do you notice anything unusual? The QRS complexes are wider than 0.12 seconds. The rate is not too fast, so aberrancy is probably not likely. Ventricular escape would result in a regular rhythm; this is also unlikely. A preexisting bundle branch block is your best reason for the wide complexes.

ECG 20-4

A rhythm strip from lead 2 shows sharp peaks of the QRS complexes occurring at irregular intervals, scooping appearance of the ST segment, and mild fluctuations of the f waves. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: Atrial: None Ventricular: About 70 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Normal
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

ECG 20-4 above is for the classic patient in atrial fibrillation with the rate controlled by digitalis. The digitalis effect is obvious and appears to be the classic scooped-out or ladle-like appearance. There is a fine f-wave pattern visible on the strip, and the irregularly irregular ventricular response is evident.

ECG 20-5

A rhythm strip from lead 2 shows sharp peaks of the QRS complexes occurring at irregular intervals, irregular morphologies of ST segments and T waves, and moderate fluctuations in some regions of the f waves. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: Atrial: None Ventricular: About 100 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Normal
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

ECG 20-5 shows the changes expected in atrial fibrillation. In addition, you will notice the QRS, ST segment, and T-wave morphologic variations we mentioned before due to fusion. In this case, it is not only fusion with the f waves but fusion with each other. The f waves are present in a coarser pattern than we have seen so far in the other strips.

ECG 20-6

Rate: Atrial: None Ventricular: About 110 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Normal
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

ECG 20-6 also shows your typical atrial fibrillation pattern with an irregularly irregular pattern and no visible P waves. There is some pretty wide variation in the R-R intervals throughout the strip. This makes the rate a bit more troublesome to calculate. Remember, take the number of complexes in a 6-second strip and multiply that number by 10 to get your answer. Some authors simply give the ranges from the slowest to the fastest rates. Either way is OK, and each has its merits. Dig effect also appears evident. Clinical correlation is warranted.

ECG 20-7

A rhythm strip from lead 2 shows sharp peaks of the QRS complexes occurring at irregular intervals and with varying morphologies between highly fluctuating f waves. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: Atrial: None Ventricular: About 130+ BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Normal
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

ECG 20-7 above shows an irregularly irregular rhythm with an uncontrolled, coarse Afib pattern. There is a bit more variation in the QRS morphology in this strip. This could be due to fusion of the QRS complexes with the coarse Afib or aberrancy (rate-related or an atypical Ashman’s phenomenon). Coarse Afib is more difficult to evaluate than fine Afib because many of the randomly occurring f waves may appear to be P waves or T waves. Calipers are an invaluable tool in these cases.

ECG 20-8

A rhythm strip from lead 2 shows sharp dips of the QRS complexes followed by broad peaks of the T waves. Between two complexes, mild fluctuations of the f waves occur. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: Atrial: None Ventricular: About 140 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Wide
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

Is ECG 20-8 uncomplicated Afib? There is some normalization of the QRS rate at the onset of the rhythm, and this breaks down into a random pattern as the strip continues. This patient has typical flutter-fibrillation pattern. At the onset of the strip, the patient has a recurrent R-R interval at about 140 BPM. There are no visible flutter waves in this lead, but you can assume they are there. The rhythm breaks down into Afib as the arrhythmia continues. Strips from other leads may help tremendously in diagnosing the rhythm.

ECG 20-9

A rhythm strip from lead 2 shows sharp peaks of the QRS complexes, scooping appearance of the ST segments, and curved peaks of the T waves. The complexes occur at high frequency, and mild to moderate fluctuations occur between some of the them. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: Atrial: None Ventricular: About 190 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Normal
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

ECG 20-9 is one fast arrhythmia! It is a narrow-complex tachycardia above 200 BPM. The most important thing in the differential diagnosis is the irregularity of the rhythm. As a matter of fact, it is completely irregularly irregular. This is uncontrolled atrial fibrillation. The faster an Afib becomes, the greater the chance of an accessory pathway being involved. You always need to consider that possibility in any patient with Afib over 200 BPM.

ECG 20-10

A rhythm strip from lead 2 illustrates Ashman’s pattern.

Rate: Atrial: None Ventricular: About 70 BPM	PR intervals: Not applicable
Regularity: Irregularly irregular	QRS width: Normal
P waves: f waves present Morphology: f waves Axis: Not applicable	Grouping: None
	Dropped beats: Not applicable
P:QRS ratio: Not applicable	Rhythm: Atrial fibrillation

Discussion:

The rhythm in ECG 20-10 is atrial fibrillation. There are no obvious P waves throughout the strip, a fine f-wave pattern, and irregularly irregular pattern. There is some aberrancy caused by Ashman’s phenomenon present on the ECG, with the third and sixth complexes being aberrantly conducted. Note that there is the classic Ashman’s pattern of a long cycle followed by aberrancy during the short cycle. The two aberrant complexes have different morphologies because the refractory area was different in both cases.