Arrhythmia Recognition: The Art of Interpretation

A rhythm strip from lead 2 shows a short, curved peak of the P wave followed by a tall, sharp peak of the QRS complex between mild fluctuations. Dots in the strip locate P waves at regular intervals. The third beat is missing. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: About 100 BPM	PR intervals: Normal, except in event
Regularity: Regular, with event	QRS width: Normal
P waves: Normal, except in event Morphology: Normal Axis: Normal	Grouping: None
	Dropped beats: Yes
P:QRS ratio: 1:1, except in event	Rhythm: Sinus tachycardia with a sinus block

Discussion:

ECG 12-1 shows a patient with an underlying sinus tachycardia. The patient has a sinus block of one complex. Notice that the pause is exactly twice the normal P-P interval found throughout the rest of the strip.

ECG 12-2

A rhythm strip from lead 2 shows a tall, sharp peak of the QRS complex between two small, curved peaks of the P and T waves. Dots in the strip locate P waves at regular intervals. The third and fourth beats are missing. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: About 92 BPM	PR intervals: Normal, except in event
Regularity: Regular, except in event	QRS width: Normal
P waves: Normal, except in event Morphology: Normal Axis: Normal	Grouping: None
	Dropped beats: Yes
P:QRS ratio: 1:1, except in event	Rhythm: Sinus rhythm with a sinus block

Discussion:

ECG 12-2 shows an underlying sinus rhythm. The patient then develops a long pause that, upon measuring, is exactly three times the normal P-P interval. This is an example of a sinus block in which two of the sinus impulses were blocked. Remember, sinus blocks can occur when either one, two, or more sinus impulses are blocked from being conducted to the atria.

ECG 12-3

A rhythm strip from lead 2 shows short, irregular peaks corresponding to P wave, QRS complex, and T wave. Dots in the strip locate P waves at regular intervals. A long pause occurs in the rhythm. — From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rate: About 76 BPM	PR intervals: Normal, except in event
Regularity: Regular, except in event	QRS width: Wide
P waves: Normal, except in event Morphology: Normal Axis: Normal	Grouping: None
	Dropped beats: Yes
P:QRS ratio: 1:1, except in event	Rhythm: Sinus rhythm with a sinus pause

Discussion:

ECG 12-3 shows a sinus rhythm with very small QRS complexes. The P, QRS, and T waves above have been labeled for your convenience. The complexes are wider than 0.12 seconds. Near the middle of the strip, the patient has a prolonged pause that is longer than two times the normal P-P interval. This is an example of a sinus pause.

ECG 12-4

A rhythm strip from lead 2 shows a short, curved peak of the P wave followed by a sharp peak of the QRS complex, which curves to the baseline. There is a long period of flatline. — 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, except in event	QRS width: Normal
P waves: Normal, except in event Morphology: Normal Axis: Normal	Grouping: None
	Dropped beats: Yes
P:QRS ratio: 1:1, except in event	Rhythm: Sinus rhythm with a sinus arrest

Discussion:

ECG 12-4 shows a patient with an underlying sinus rhythm. The patient then has a very prolonged pause that was longer than four times the normal P-P interval. This is an example of a sinus arrest. The patient also has some very impressive ST-segment elevation. Evaluation with a full 12-lead ECG is indicated to evaluate the possibility of an acute myocardial infarction (MI). Clinical correlation is also indicated to evaluate the patient’s hemodynamic status because of the possible MI and the sinus arrest.