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Symptomatic Bradycardia

RULES FOR SINUS
BRADYCARDIA

REGULARITY	R-R intervals are regular, overall rhythm is regular.
RATE	The rate is less than 60 bpm, but usually more than 40 bpm.
P WAVE	There is one P wave in front of every QRS. The P waves appear uniform.
PR INTERVAL	Measures between 0.12 and 0.20 seconds in duration. PR interval is consistent.
QRS COMPLEX	Measures less than 0.12 seconds.

Table 11

RULES FOR FIRST DEGREE HEART BLOCK

REGULARITY	R-R intervals are regular, overall rhythm is regular.
RATE	The rate depends on the underlying rhythm.
P WAVE	There is one P wave in front of every QRS. The P waves appear uniform.
PR INTERVAL	Measures more than 0.20 seconds in duration. PRI is consistent.
QRS COMPLEX	Measures less than 0.12 seconds.

Table 12

RULES FOR 2ND DEGREE TYPE I AV BLOCK (WENCKEBACH/MOBITZ I)

REGULARITY	R-R interval is irregular, but there is usually a pattern to it. The R-R interval gets longer as the PR interval gets longer.
RATE	The ventricular rate is usually slightly lower than the atrial rate due to some atrial beats not being conducted. The atrial rate is usually normal.
P WAVE	P waves are upright and uniform. Most complexes will have a P wave in front of them; however, there will be some P waves that do not have a QRS complex.
PR INTERVAL	PR interval gets progressively longer until there is a dropped QRS complex.
QRS COMPLEX	Measures less than 0.12 seconds.

Table 13

RULES FOR 2ND DEGREE TYPE II AV BLOCK (MOBITZ II)

REGULARITY	If there is a consistent conduction ratio, then the R-R interval will be regular. If the conduction ratio is not constant, the R-R interval will be irregular.
RATE	The atrial rate is normal. The ventricular rate is slower, usually 1/2 to 1/3 slower than the atrial rate.
P WAVE	P waves are upright and uniform. There is not a QRS following every P wave.
PR INTERVAL	PR interval can only be measured on conducted beats, and it is usually constant across the strip. It may or may not be longer than a normal PR interval (0.12 seconds)
QRS COMPLEX	Measures less than 0.12 seconds.

Table 14

RULES FOR 3RD
DEGREE AV BLOCK

Complete Heart Block

REGULARITY	R-R interval is regular. P-P interval is also regular.
RATE	The atrial rate is regular and normally 60 to 100. Rate of QRS complexes is dependent on the focus. If the focus is ventricular, the rate will be 20 to 40. If the focus is junctional, the rate will be 40 to 60.
P WAVE	P waves are upright and uniform. There is not a QRS following every P wave.
PR INTERVAL	PR interval can only be measured on conducted beats, and it is usually constant across the strip. It may or may not be longer than a normal PR interval (0.12 seconds).
QRS COMPLEX	Interval may be normal but is more likely to be prolonged.

Table 15

SYMPTOMATIC BRADYCARDIA

Bradycardia is defined as a heart rate of less than 60 beats per minute. While any heart rate less than 60 beats per minute is considered bradycardia, not every individual with bradycardia is symptomatic or having a pathological event. Individuals in excellent physical shape often have sinus bradycardia. Symptomatic bradycardia may cause a number of signs and symptoms including low blood pressure, pulmonary edema and congestion, abnormal rhythm, chest discomfort, shortness of breath, lightheadedness, and/or confusion. Symptomatic bradycardia should be treated with the ACLS Survey. If bradycardia is asymptomatic but occurs with an arrhythmia listed below, obtain a consultation from a cardiologist experienced in treating rhythm disorders.

SYMPTOMS OF BRADYCARDIA

Shortness of breath
Altered mental status
Hypotension
Pulmonary edema/congestion
Weakness/dizziness/lightheadedness

SYMPTOMATIC BRADYCARDIA REVIEW

Sinus Bradycardia

Normal rhythm with slow rate

First Degree AV Block

PR interval is longer than 0.20 seconds

Type I Second Degree AV Block

PR interval increases in length until QRS complex is dropped

Type II Second Degree AV Block

Constant PR intervals (may be prolonged) before a random QRS is dropped

Third Degree AV Block

P waves and QRS complex are not coordinated with each other

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