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Symptomatic Braycardia

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sinus 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. PRI is consistent.
QRS Measures less than 0.12 seconds.

first degree av block

RULES FOR FIRST DEGREE AV 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 Measures less than 0.12 seconds.

second degree type 1 av block

RULES FOR 2ND DEGREE TYPE I AV BLOCK (WENKEBACH)

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 higher 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 that do not have a P wave.
PR INTERVAL PR interval gets progressively longer until there is a dropped QRS complex.
QRS Measures less than 0.12 seconds.

second degree type 2 av block

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

REGULARITY 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 will be normal. The ventricular rate will be 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 PRI 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 PRI (0.12 seconds).
QRS Measures less than 0.12 seconds.

third degree av block

RULES FOR 3RD DEGREE AV BLOCK (COMPLETE HEART BLOCK)

REGULARITY R-R interval will be regular. P-P interval will also be regular.
RATE The atrial rate will be regular and normally be 60-100. Rate of QRS complexes is dependent on the focus. If the focus is ventricular, the rate will be 20-40. If the focus is junctional, the rate will be 40-60.
P WAVE P waves are upright and uniform. There is not a QRS following every P wave.
PR INTERVAL PRI 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 PRI (0.12 seconds).
QRS Interval may be normal but is more likely to be prolonged

SYMPTOMS OF BRADYCARDIA

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

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 patient with bradycardia is symptomatic or having a pathological event. People 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 an ACLS response. If bradycardia is asymptomatic but occurs with an arrhythmia listed below, obtain a consultation from a cardiologist experienced in treating rhythm disorders.

Quick Review of Symptomatic Bradycardia

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

PR interval is the same length with intermittently dropped QRS complex

THIRD DEGREE AV BLOCK

PR and QRS are not coordinated with each other

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