Cardiology ECG's Flashcards
What is an ECG?
Recording of electrical activity of the heart
How is an ECG recorded?
Attach electrode or leads to pt. Add conducting agents then hook to ECG machine.
Conducting agents
Alcohol
Ultrasound gel
Limb leads
Lead 1
Lead 2: most common
Lead 3
All make up “Einthoven’s triangle”
Augmented limb leads
- aVR
- aVL
- aVF
Patient placement for ECG:
Pt in R lateral recumbency (if possible) on Table on blanket or padded table
Pt breathing normal: avoid interference/artifact
Interference/artifact causes:
Pt movement: panting,trembling, etc
60-cycle: electrical interference
Lead placement on patient:
Right Axillary: White Lead Right Inguinal: Green Lead Left Axillary: Black Lead Left Inguinal: Red Lead \+/- Chest: Tan/brown Lead
P wave
Small, + deflection in lead 2.
SA node has fired and atria has depolarized.
Diastolic phase
PR Interval
Period of time where AV node is causing a delay in conduction.
QRS Complex
Q = -, R = +, S = - deflections.
Largest part.
Ventricular depolarization a.k.a contraction.
Systolic phase
T wave
+ or - deflection – uniform.
Should be 25% of the amp of the R wave.
Ventricular depolarization or relaxation.
ST segment
Period of time between ventricular contraction and relaxation.
RR Interval
Period of time between cardiac contractions.
What is an arrhythmia?
A disruption of normal electricity in the heart.
Causes of arrhythmia:
- Abnormal rate of rhythm
2. Abnormal site of origin
Intrinsic pacemaker rates:
- Dependent on size of animal/species
SA Node
70-120 bpm
Atrial muscle
0 bpm
AV Node
40-60 bpm
Bundle of HIS
40-60 bpm
Bundle branches
20-40 bpm
Purkinje fibers
20-40 bpm
Steps in evaluations: Step 1
Evaluate R-R Intervals – must be within a 10% variation.
Steps in evaluations: Step 2
Determine if impulses are sinus or not
Sinus
A,B,C
Normal conduction occurred = heart contracted normally
A. Evaluate P waves:
normal = small and positive deflection
Inverted P waves:
Impulse originates at the AV junction
Absent P waves:
Impulse originated somewhere at ventricles.
B. Look at relationship between P waves and QRS:
- Every P wave must have a QRS
- PR interval should be consistent
C. Evaluate T waves:
+ or - deflection– uniform. Should be 25% of the amp. of the R wave.
Steps in evaluations: Step 3
Look for anything unusual