Cardiology Review and Intro to ECGs

Vocabulary flashcard from ECG terminology.

what are the special properties of cardiac cells

excitable, conductive, automatic, refractory

three things cardiac innercation controls

heart rate and blood pressure, conduction of electrical impulses through the heart muscle, myocardial contraction

system that works to slow the heart rate

parasympathetic nervous system

system that works to increase heart rate and blood pressure

sympathetic nervous system

SA node

stimulates atrial contraction - main pacemaker of the heart

AV node

slows conduction, allowing atria to fully contract - controls length of diastole

bundle of his

signals beginning of systole

6 ways to evaluate heart function

pulse rate and quality/ heart rate and rhythm, heart sounds, mucous membrane color, capillary refill time, Electrocardiogram

what does ECG tell us

heart rate and rhythm, chamber enlargement, visual representation of how the electrical impulses move through the heart, can help determine best course of treatment

ECG indications

evaluation of arrhythmias and heart rate, history of syncope, weakness or trauma, pre - anesthetic work - up, cardiac monitoring during anesthesia, critical illness, concurrent drug administration

how many of 4 cables become charged - Lead Polarity

2 out of 4 cables become charged - one limb becomes positive and a different limb becomes negative

we usually look at Lead II on an ECG, what happens when the lead is changed

the polarity of the electrodes are changed - changing the appearance and amplitude of the ECG waves which can affect interpretation of the heart's electrical activity.

Lead I

RA - LA +

Lead II

RA - LL +

Lead III

LA - LL +

How could the ECG tracing change when using Einhoven’s triangle

electrical impulses traveling toward the + pole of the lead will crate a positive or upward defection, electrical impulses traveling away from the + lead will cause a negative deflection

the magnitude of the deflection is proportional to the mass of the muscle

true

poper positioning for ECG

right lateral recumbency, legs 90 degrees to the body, clips should be attached near the elbows/stifles, clips should not touch each or the table, patient and restrainer must remain still

correct cable placement

white - right forelimb

green lead - right hind limb

black - left forelimb

red lead - left hind limb

what is calibration

used to calculate the amplitude of the waves on an ECG tracing

calibration settings

5mm/mv - often used for large animals

10mm/mv - often used for dogs

20 mm/mv o often used for cats

what do abnormally long times on an ECG tracing mean

one or more chambers are enlarged or ± faulty electrical conduction

what do shorter/faster than normal times mean

SA node is being driven to contract faster by sympathetic nervous system (fear) or by drugs

ectopic focus - damaged heart tissue/muscle cell (usually in the ventricles

what do the amplitudes of the p wave and the QRS complex indicate

p wave - size of atrial mass

qrs complex - size of ventricular mass

what do larger than normal amplitudes indicate

corresponding chamber enlargement

what do smaller than normal amplitudes indicate

the corresponding muscle mass is smaller than normal