ECG Flashcards
The p wave is?
Atrial depolarization
The PR interval is?
conduction from SA to AV node
QRS interval is
ventricular muscle depolarization
T wave is
ventricular muscle repolarization
Which lead is used for amplitude measurements?
Lead II- right shoulder to left leg
Positive waves are?
waves traveling toward the positive electrode
ECG is best to evaluate?
Heart rate, heart rhythm, and conduction
What are the 4 steps to evaluate and ECG?
- Evaluate for artifacts, quality, and calibrations
- Determine the heart rate
- Name the cardiac rhythm
- Evaluate the P-QRS-T complex configurations and morphologies
What does amplitude increase indicate?
Chamber enlargement
What is standard calibration for ECG?
Gain: 10mm/mV = 1cm/mV
- each small box is 1mm
at 50mm/sec, 1 small box =?
0.02 seconds
Name some artifacts that can render ECG uninterpretable?
purring, respiration movememt, motion, muscle twitches
Normal feline heart rate
140-220
Normal canine heart rate
60-160
What are the two most common cardiac rhythms?
Sinus rhythm and sinus arrhythmia
What is a sinus rhythm?
normal P wave with similar shaped QRS and similar P-P interval
What is sinus arrhythmia?
irregular rhythm originated from the SA node, normal in many species, normal QRS for every P with varying normal heart rate because of high vagal tone, may see varying P height
What is a wandering pacemaker?
varying P height, seen with sinus arrhythmia
How tall should the T wave be
< 1/3 QRS, can even be negative or biphasic
When may you see a sinus bradycardia in cattle?
Lack of food intake
What are the normal cardiac rhythms of horses?
sinus rhythm
sinus arrhythmia
first or second degree AV block
What is the difference between a premature and and escape ectopic beat?
PVC occurs earlier than expected and escape beats occur later than expected
What is an atrial ectopic beat (atrial premature contraction)?
Has P wave that is too early, may be on top of T wave or not visible, normal QRS
What is sinus bradycardia/bradyarrhythmia?
Normal p with every QRS, but at a slow rate
Treatment for sinus bradycardia?
Identify and address underlying cause, can give atropine if because of anesthetic complications
What is sick sinus syndrome?
abnormal rhythm disturbance in older small breed dogs, combo of:
- sinus bradycardia
- sinus arrest (pause with no P)
- AV block
- Supraventricular tachycardia- after a long pause
What are first, second, and third degree AV block?
1st: prolonged PR
2nd: intermittent blocked P wave
3rd: P and QRS unrelated
How do you differentiate pathologic 2nd degree AV block from high vagal tone?
Give atropine- if block disappears, high vagal tone
What is the only treatment fr 3rd degree AV block?
Pacemaker
What are the 3 types of tachycardia?
- sinus
- supraventricular
- ventricular
Describe sinus tachycardia
Normal p, normal qrs
Describe supraventricular tachycardia:
abnormal p, normal QRS
*3 or mor APCs or SVPCs in a row
Describe ventricular tachycardia:
no associated p, wide/bizarre QRS
What are the causes of sinus tachycardia?
Response to systemic issue, pain, excitement, hypotension
What are causes of supraventricular tachycardia?
Atrial enlargement (most common in small animals)
Enlarged hilar lymph nodes
Thoracic masses
Pulmonary inflammation
Electrolyte disturbances
*can occur in horses without structural heart disease
T/F: Atrial fibrillation is not a type of supraventricular tachycardia
False- no clear p-waves, but QRS are normal
T/F: All cases with atrial fibrillation will show bumpy baseline
False- small patients may not show bumpy baseline
What are the most common causes of atrial fibrillation in small animals?
Severe atrial enlargement caused by dilated cardiomyopathy or chronic valvular disease
T/F: Atrial fibrillation is uncommon in cats
T
What is the treatment goal for SVT or A fib?
Decrease heart rate to normal range
What drugs could be used to decrease heart rate in patients with SVT or A fib?
Digoxin,
Calcium Channel Blockers (Diltiazem)
Beta blockers (Atenolol)
T/F: “Lone a-fib” occurs in horses, humans.
True-
lone a-fib means there is no underlying heart disease
T/F: The most common cause of bovine a-fib is primary GI disease
True
T/F: Equine lone fib can successfully be converted with medical treatment (quinidine + digoxin or amiodarone)
True
T/F: Recurrence of a-fib in converted horses is uncommon.
False
T/F: V-tach can result in sudden death.
True
T/F: Anti-arrhythmics can have pro-arrhythmic effects, potentially making arrhythmias worse.
True: you must make sure you have reason to treat arrhythmias
Name some indications to treat arrhythmias:
- Paroxysms or sustained VT > 140-160bpm
- > 20 VPCs per minute
- Multiform VPCs
- Arrhythmias with myocardial failure present
- Breeds at risk for sudden death (dobys and boxers)
- Clinical hypotension
- VPCs close to the T wave of the proceeding complex
- Critically ill patients
What is the acute/emergency treatment for arrhythmias?
Lidocaine- IV in a bolus
- side effects can include seizures and vomiting
What are chronic treatments for arrhythmias available orally?
Mexilitine (similar to lidocaine) Sotalol (B blocker and class 3) Atenolol (B blocker)
T/F: V-fib is fatal unless electrical defribrillation is done in time.
True- no pulses, antiarrhythmics inneffective
