Arrhythmia Recognition: The Art of Interpretation

A rhythm strip from lead 2 illustrates sinus rhythm with PJC.

Rate: About 80 BPM	PR intervals: Normal, except in event
Regularity: Regular with an event	QRS width: Normal
P waves: Present, except in event Morphology: Normal, except in event Axis: Normal, except in event	Grouping: None
	Dropped beats: Present
P:QRS ratio: 1:1, except in event	Rhythm: Sinus rhythm with a PJC

Discussion:

ECG 22-1 shows a sinus rhythm. The cadence of the rhythm is interrupted by a premature complex (blue arrow) that is slightly different in morphology than the other QRS complexes. There is no real noticeable change in the T wave prior to the event, and the pause is compensatory. Both of these findings point toward a PJC. The slight irregularity is due to some aberrancy. Note that both the normal and aberrant complexes start off in the positive direction.

ECG 22-2

A rhythm strip from lead 2 shows sinus rhythm with multiple PJCs.

Rate: About 72 BPM	PR intervals: Normal, except in event
Regularity: Regular with an event	QRS width: Normal
P waves: Present, except in event Morphology: Normal, except in event Axis: Normal, except in event	Grouping: None
	Dropped beats: Present
P:QRS ratio: 1:1, except in event	Rhythm: Sinus rhythm with multiple PJCs

Discussion:

ECG 22-2 shows a sinus rhythm with some ST-segment abnormalities, which could be due to digitalis effect (note the ladle-like or scooped-out appearance of the complexes). The two premature complexes (blue arrows) are slightly different in morphology. The first is a PJC with some aberrancy. The height is slightly shorter, but so is the fifth complex. The terminal S wave in the QRS complexes of the third complex may actually be a buried, inverted P wave. The morphology of the second PJC is exactly like the normal ones.

ECG 22-3

A rhythm strip from lead 2 shows a normal sinus rhythm. An arrow pointing toward a PJC shows the P wave buried to the initial portion of the QRS complex. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: About 80 BPM	PR intervals: Normal, except in event
Regularity: Regular with an event	QRS width: Normal
P waves: Present, except in event Morphology: Normal, except in event Axis: Normal, except in event	Grouping: None
	Dropped beats: Present
P:QRS ratio: 1:1, except in event	Rhythm: Sinus rhythm with a PJC

Discussion:

ECG 22-3 shows a nice sinus rhythm clipping along at 80 BPM. The cadence of the ventricular complexes is broken up by a premature complex that is narrow and similar in morphology to the rest of the complexes. This is obviously a PJC. The cadence of the atrial complexes, however, is not broken and persists right through the PJC, making this a compensatory pause. Notice the buried upright P wave within the PJC (blue arrow). The fact the P wave is upright means that it did not come from the PJC.

ECG 22-4

A rhythm strip from lead 2 illustrates sinus tachycardia with PJC.

Rate: About 110 BPM	PR intervals: Normal, except in event
Regularity: Regular, except in event	QRS width: Normal
P waves: Present, except in event Morphology: Normal, except in event Axis: Normal, except in event	Grouping: None
	Dropped beats: Present
P:QRS ratio: 1:1, except in event	Rhythm: Sinus tachycardia with a PJC

Discussion:

This patient has an underlying sinus tachycardia and one wide, bizarre ventricular-looking complex (ECG 22-4). Is it a PVC or a PJC with aberrancy? Let’s look at how they both start. They both are positive, and notice that the very early onset of both the normal beats and the aberrant one are identical. This is an aberrantly conducted PJC. The negative deflection after the tall R wave may be an S wave and part of the complex or a buried P wave. It is difficult, if not impossible, to say which is correct from this strip.

ECG 22-5

A rhythm strip from lead 2 illustrates sinus rhythm with multiple aberrant PJCs.

Rate: About 86 BPM	PR intervals: Normal, except in event
Regularity: Regular with events	QRS width: Normal, events are wide
P waves: Present, except in event Morphology: Normal, except in event Axis: Normal, except in event	Grouping: None
	Dropped beats: Present
P:QRS ratio: 1:1, except in event	Rhythm: Sinus rhythm with multiple PJCs

Discussion:

Once again, we are faced with a diagnostic challenge. Are the wide, premature complexes on ECG 22-5 of junctional or ventricular origin? How do both aberrant beats start? They start with positive waves that are identical to the start of the sinus QRS complexes. Then an aberrancy begins to develop along a slightly different location for each one, accounting for the slight differences in morphology between the two.

ECG 22-6

A rhythm strip from lead 2 shows a curved peak of the P wave, a sharp peak of the QRS complex, and a wide peak of the T wave. A PJC occurs in the strip. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: About 58 BPM	PR intervals: Normal, except in event
Regularity: Regular with an event	QRS width: Normal
P waves: Present, except in event Morphology: Normal, except in event Axis: Normal, except in event	Grouping: None
	Dropped beats: Present
P:QRS ratio: 1:1, except in event	Rhythm: Sinus bradycardia with a PJC

Discussion:

ECG 22-6 shows a sinus bradycardia with a PJC. The PJC causes a noncompensatory pause and the sinus rate is reset after the PJC. The ST-segment depressions found on this strip should make you think about getting a full 12-lead ECG to evaluate the possibility of ischemia. Clinical correlation would also be extremely helpful in establishing a clinical diagnosis.

ECG 22-7

A rhythm strip from lead 2 shows a fluctuating peak of the P wave, a sharp peak of the QRS complex, a fluctuating ST segment, and a wide and curved peak of the T wave. A PJC occurs in the strip. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: About 64 BPM	PR intervals: Normal, except in event
Regularity: Regular with an event	QRS width: Normal
P waves: Present, except in event Morphology: Normal, except in event Axis: Normal, except in event	Grouping: None
	Dropped beats: Present
P:QRS ratio: 1:1, except in event	Rhythm: Sinus rhythm with a PJC

Discussion:

ECG 22-7 is another example of a PJC. The morphology of the T wave immediately prior to the PJC is a bit altered, but the PR interval would have to be exceedingly long in order for a P wave to buried in there. The QRS morphology is similar to the others and narrow, signifying a supraventricular origin.