Cardiac Rhythms and Dysrhythmias
Characteristics ,Question and Answer Session with a
Perfect 100% Accuracy, 2024
Normal Sinus Rhythm Characteristics
Rate: 60-100
Rhythm: regular
P:QRS: 1:1
PR Interval: 0.12-0.20
QRS Complex: 0.06-0.10
Sinus Tachycardia Characteristics
Rate: 101-150
Rhythm: regular
P:QRS: 1:1 (with very fast rates, P wave may hidden in preceding T wave.)
PR Interval: 0.12-0.20
QRS Complex: 0.06-0.10
Sinus Bradycardia Characteristics
Rate: <60
Rhythm: regular
P:QRS: 1:1
PR Interval: 0.12-0.20
QRS Complex: 0.06-0.10
Atrial Flutter Characteristics
Rate: atrial 240-360; ventricular rate depends on degree of AV block and usually is
<150
Rhythm: atrial regular; ventricular usually regular
P:QRS: 2:1, 4:1, 6:1; may vary
PR Interval: not measured
QRS Complex: 0.06-0.10
Atrial Fibrillation Characteristics
Rate: atrial 300-600 (too rapid to count); ventricular 100-180 in untreated patients
Rhythm: irregularly irregular
P:QRS: variable
PR Interval: not measured
QRS Complex: 0.06-0.10
Paroxysmal Supraventricular Tachycardia (PSVT) Characteristics
,Rate: 100-280 (usually 150-200)
Rhythm: regular
P:QRS: P waves often not identifiable
PR Interval: not measured
QRS Complex: 0.06-0.1
Ventricular Tachycardia Characteristics
Rate: 100-250
Rhythm: regular
P:QRS: P waves usually not identifiable
PR Interval: not measured
QRS Complex: 0.12 sec or greater; bizarre shape
Ventricular Fibrillation Characteristics
Rate: too rapid to count
Rhythm: grossly irregular
P:QRS: no identifiable P waves
PR Interval: none
QRS Complex: bizarre, varying in shape and direction
First Degree AV Block Characteristics
Rate: usually 60-100
Rhythm: regular
P:QRS: 1:1
PR Interval: >0.21
QRS Complex: 0.06-0.1
Second Degree AV Block - Type 1 Characteristics
Rate: 60-100
Rhythm: atrial regular; ventricular irregular
P:QRS: 1:1 until P wave blocked with no subsequent QRS complex
PR Interval: progressively lengthens in a regular pattern
QRS Complex: 0.06-0.1; sudden absence of QRS complex
Second-Degree AV Block - Type 2 Characteristics
Rate: atrial 60-100 bpm; ventricular <60
Rhythm: atrial regular; ventricular irregular
P:QRS: typically 2:1, may vary
PR Interval: constant PR interval for each conducted QRS complex
QRS Complex: 0.06-0.1
Third-Degree AV Block (Complete Heart Block) Characteristics
Rate: atrial 60-100; ventricular 15-60
Rhythm: atrial regular; ventricular regular
P:QRS: no relationship between P waves and QRS complexes; independent rhythms
PR Interval: not measured
QRS Complex: 0.06-0.1 if junctional escape rhythm; >0.12 if ventricular escape rhythm
, Junctional Escape Rhythm Characteristics
Rate: 40-60; junctional tachycardia 60-140
Rhythm: regular
P:QRS: P waves may be absent, inverted, and immediately preceding or succeeding
QRS complex or hidden in QRS complex
PR Interval: <0.10
QRS Complex: 0.06-0.1
Premature Ventricular Contractions (PVCs) Characteristics
Rate: variable
Rhythm: irregular, with PVC interrupting underlying rhythm and followed by a
compensatory pause
P:QRS: no P wave noted before PVC
PR Interval: absent with PVC
QRS Complex: wide (>0.12) and bizarre in appearance; differs from normal QRS
complex
Sinus Tachycardia Management
Treated on if symptomatic or patient is at risk for myocardial damage.
Treat underlying cause (hypovolemia, pain, fever). Beta-blockers or verapamil may be
used.
Sinus Bradycardia Management
Treated on if symptomatic.
IV atropine or isoproterenol and/or pacemaker therapy may be used.
Paroxysmal Supraventricular Tachycardia (PSVT) Management
Treat if symptomatic.
Treatment may include vagal maneuvers (Valsalva, carotid sinus massage); oxygen
therapy; adenosine or a beta-blocker; temporary pacing, or synchronized cardioversion.
Atrial Flutter Management
Synchronized cardioversion; medications to slow ventricular response such as a beta-
blocker or calcium channel blocker, followed by a Class I antidysrhythmic agent or
amiodarone.
Atrial Fibrillation Management
Synchronized cardioversion; medications to reduce ventricular response rate:
Metoprolol, diltiazem, or digoxin; anticoagulant therapy to reduce risk of clot formation
and stroke.
Junctional Escape Rhythm Management
Treat cause if symptomatic
Premature Ventricular Contractions Management
Treat if symptomatic or in presence of severe heart disease. Advise against stimulant
use (caffeine, nicotine).
Beta-blockers or Class I or III antidysrhythmic agents may be used for patients with
severe heart disease who are symptomatic.
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