ECG's

Most common Tachyarrythmias

Sinus Tachycardia, Ventricular Tachycardia, Supraventricular/Atrial Tachycardia, Atrial Fibrillation, Atrial Flutter

Sinus Rhythm

A type of Normal Rhythm

• P wave for every QRS

• Rhythm is regular

• Intervals have normal values

Respiratory Sinus Arryhmthmia

A type of Normal Rhythm

• Same as sinus rhythm except

• Heart rate varies with respiration

• Increases with inspiration

• Decreases with expiration

Wandering Pacemaker

A normal type of Normal Sinus

• P waves differ in size within the same lead

• Pacemaker site within SA node shifts locations

Sixty-cycle interference

A type of Artifact

• Electrical interference pattern due to equipment not properly grounded

• Examples of causes:

• Power cord not grounded

• Clips not contacting skin

• Clips are dirty or loosely attached to the cable

• Legs are touching

• Cables are touching the table or restrainer

• Fluorescent lights

• Other equipment running nearby

Muscle Tremors or Purring

A type of Artifact

• Rapid irregular movements of baseline

• Correct by calming the patient or reapplying the clips

Wandering Baseline

A type of Artifact

• Caused by respiratory movement

• Correct by holding patient’s mouth closed for 3-4 seconds

Sinus Tachycardia

A type of Atrial/Supraventricular Tachyarrhythmias

• Normal ECG complexes

• Fast heart rate

• R-R interval is consistent

• Causes: stress, drugs, shock, anemia, thyroid dz, CHF

• Tx: address underlying cause

Supraventricular Premature Complexes

A type of Atrial/Supraventricular Tachyarrhythmias

• P waves look different (taller, smaller, hidden, or different shape)

• Impulse initiated in atria not SA node

• Cause: usually due to atrial enlargement

Supraventricular Tachycardia

A type of Atrial/Supraventricular Tachyarrhythmias

• 4 or more SPCs in a row

• Causes: congenital malformation of the conduction system, thyroid dz, anemia, electrolyte abnormalities, trauma

• Affects dogs and cats

• Treatment: beta blockers (sotalol, atenolol) and calcium channel blockers (diltiazem), ablation

Atrial Fibrillation

A type of Atrial/Supraventricular Tachyarrhythmias

• No P waves, undulating PR segments, presence of f waves (fibrillations on baseline)

• Irregular intervals between R waves

• Tx: diltiazem, atenolol, digoxin, cardioversion (rate often reverts back and meds are used to slow the rate)

Atrial Flutter

A type of Atrial/Supraventricular Tachyarrhythmias

• Rapid rate

• Saw-toothed “flutter” waves instead of P
  waves

• Rhythm degenerates into atrial
  fibrillation

• Tx: drug therapy or cardioversion

1st Degree AV Block

A type of Bradyarrythmia

• Prolonged PR interval

2nd Degree AV Block

A type of Bradyarrythmia

• Occasional missing QRS complexes

3rd Degree AV Block

A type of Bradyaarythmia

• No relationship between P waves and QRS
  complexes

Sinus Pause/Arrest

A type of Bradyarrythmia

• SA node fails to fire then resumes or a
  different pacemaker fires

Sinus Bradycardia

A type of Bradyarrythmia

• Heartbeat is too slow

• Too slow varies by species:

• Cat: <100 beats/min

• Dog: <60 beats/min

• Associated with cardiac arrest

• Tx: address underlying cause (drugs, hypothermia, vagal tone, etc.)

Sick Sinus Syndrome

A type of BradyarrhySA node stops firing, heart stops beating

•Often has a rhythm with many long pauses, sinus bradycardia, may see tachycardia as well

•Tx: pacemaker

Ventricular Asystole

A type of Bradyarrhythmias

• No ventricular complexes (“flat line”)

• No pulse (heart is no longer beating)

• CARDIAC ARREST—initiate CPR (epinephrine)

• Irreversible brain damage occurs within 3-4 minutes from lack of oxygen

Ventricullar Fibrillation

A type of Ventricular Tachyarrhythmia

• Rapid heart rate, irregular wide and bizarre waves

• No P, QRS, or T waves seen

• Oscillations seen on ECG can be large and coarse or small and fine

• No pulse—cardiac arrest is near

• Tx: defibrillation

Ventricular Premature Complexes

A type of Ventricular Tachyarrhythmia

• Electrical impulses that arise from ectopic foci in the ventricles

• They do not travel through the special conduction system, but through ordinary muscle which slows conduction

• Wide and bizarre QRS complexes

• A single VPC is not life threatening, but strings of VPCs are a concern

Ventricular Tachycardia

Type of Ventricular Tachyarrhythmia

• VPCs from an ectopic focus in the ventricles

• Can be intermittent (3 or more in a row) or continuous (all complexes are VPCs)

• Rate is regular and >180 bpm

• QRS complexes are wide and bizarre

• No relationship between P and QRS (P waves not discernible)

• Associated with cardiac arrest

• Tx: defibrillation

Electromechanical Dissociation

• Term which means there is electrical activity
  recorded on the ECG, but no heartbeat can be
  auscultated

• Pulseless rhythm (Pulseless Electrical Activity)

• The electrical activity can look like anything

• Patient is near death. Initiate cardiac
  resuscitation NOW

• Always monitor manually. DO NOT RELY ON
  MACHINES!