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VETERINARY CLINICAL CARDIOLOGY
CARDIOLOGY CONCEPTS
Electrocardiology
Dysrhythmias
1. Approach to the ECG to assess dysrhythmias.

Try the diagnostic algorithm here (a chart form is here).

  1. Determine the ventricular rate - note paper speed.

  2. Determine the atrial rate - note paper speed.

  3. Are P and QRS associated?
    • same rate
    • reasonable PR interval
    • consistent PR interval

  4. Determine PR interval - note paper speed
    • does it vary?

  5. Are there any P waves that are not followed by a QRS complex?

  6. Are there any QRS complexes with no P waves?

  7. Determine the width of the QRS complexes - note paper speed.

  8. Is the rhythm regular or irregular?

  9. Any premature beats? - note morphology and duration

  10. Are the P waves positive in lead II?

  11. Are the QRS complexes of normal morphology?

The critical feature with most dysrhythmias is to identify P waves (if present), note if the atrial rate is equal to, less than, or greater than the ventricular rate, and note if there is any relationship between the P waves and the QRS complexes.

Dysrhythmias - Algorithm to Diagnose Cardiac Rhythm Disorders By Electrocardiography

RHYTHM
HEART RATE
P WAVES PRESENT?
DO QRS COMPLEXES HAVE ASSOCIATED P WAVES?
DISORDERS
REGULAR
SLOW
YES
YES

Sinus Bradycardia

2nd Degree Heart Block

NO

3rd Degree Heart Block

NO

Hyperkalemia

Persistent Atrial Standstill

NORMAL
YES
YES

Normal Sinus Rhythm

2nd Degree Heart Block

Atrial Flutter

NO
Ventricular Tachycardia
NO

Hyperkalemia

Persistent Atrial Standstill

FAST
YES
YES

Sinus Tachycardia

Supraventricular Tachycardia

Atrial Flutter

NO

Ventricular Tachycardia

Non-Paroxysmal Junctional Tachycardia

NO

Supraventricular Tachycardia (P waves present but buried in QRS or T)

RHYTHM
HEART RATE
P WAVES PRESENT?
DO QRS COMPLEXES HAVE ASSOCIATED P WAVES?
DISORDERS
IRREGULAR
SLOW
YES
YES

Sinus Bradycardia

Sinus Arrhythmia

Sick Sinus Syndrome

2nd Degree Heart Block

NO
NO

Slow Atrial Fibrillation

NORMAL
YES
YES

Sinus Arrhythmia

2nd Degree Heart Block

Atrial Flutter

NO
Ventricular Tachycardia (rhythm is usually regular)
NO

Atrial Fibrillation

FAST
YES
YES

Sinus Tachycardia

Atrial Flutter

Supraventricular Tachycardia

NO

Ventricular Tachycardia (rhythm is usually regular)

Non-paroxysmal Junctional Tachycardia

NO

Atrial Fibrillation

production