ECG revision Flashcards
What is convention for recording an ECG?
Convention for recording an ECG is with the patient in RIGHT lateral recumbency with limbs perpendicular to the long axis of the body. In fractious patients, it may be necessary to allow them to settle without restraint (e.g. in a basket). Also, patients with breathing difficulties may be better assessed in sternal recumbency.
How should ECG leads be applied?
Spirit + crocodile clips OR
Clip, gel and sticky electrode pad
Red: = Right foreleg: Behind Elbow
Yellow = Left foreleg: Behind Elbow
Green = Left rear leg: In front of Stifle
Black = Right rear leg: In front of Stifle
NOTE: Avoid draping the leads over the patients. Leads should also be untangled.
How should the ECG be taken?
- Allow the patient to settle. Electrical noise is the enemy of the ECG!!! This can be caused by the patient: shivering, movement, heavy panting or purring; or by mains interference.
- Switch on and set-up the ECG machine, including entering patient data as appropriate. NOTE: The instructions for this will vary with each machine. Uni machine: 50 or 25 speed–Manu Lead 2 –Filter ON– Sen 20– Run Reg—place clips Red Right Fore Yellow Left Fore Green Left Hind N – neutral black - Right Hind
- Run a lead II rhythm strip at 50mm/sec
- Run leads I, II, III and then augmented leads (aVL, aVR, aVF) at 25mm/sec.
What happens during the isovolumetric contraction phase?
During the isovolumetric contraction phase, both the AV and semilunar valves are closed. It is terminated when the semilunar valves open. Occurs during ventricular systole
What happens in the isovolumetric phase?
Both AV and semilunar valves are closed during the isovolumetric relaxation phase too. It is terminated by the opening of the AV valves. Occurs during ventricular diastole
Describe the cardiac sounds?
S1: Lub sound. Caused by AV valve closure
S2: Dub sound. Caused by semilunar valve closure
S3: Faint, can be heard in horses. Caused by ventricular diastole (blood rushing into ventricles)
S4: Caused by atrial systole (contraction of atria)
Describe atrial pressure terms?
a wave: atrial systole (contraction)
c wave: bulging of AV valve due to increased ventricular pressure
x descent: drop in pressure after ventricles empty
v: passive atrial filling
y descent: emptying of atria into ventricles
What is a long P wave indicative of?
Tall P wave?
A long p wave is suggestive of left atrial enlargement.
A tall p wave is indicative of right atrial enlargement since the larger the right atrium (location of SAN), a larger wave of excitation is produced
What does an normal ECG look like?
P wave, narrow QRS complex and a t wave
List types of bradydysrhythmias?
Sinus arrest: Pause with no complexes
Persistent Atrial Standstill: No P waves
1st degree AV Block: Long P- R interval
2nd Degree AV Block: P complex but no QRS Complex afterwards
3rd Degree AV Block: No relationship between P waves and QRS Complexes
What is this?
Sinus Arrest
Pause with no complexes
What is this?
Persistent Atrial Standstill: No P waves
What is this?
1st degree AV Block: Long P- R interval
What is this?
2nd Degree AV Block: P complex but no QRS Complex afterwards
what is this?
3rd Degree AV Block: No relationship between P waves and QRS Complexes
Look at this?
What is this?
Supraventricular Premature Complexes
P wave is early or P wave a different shape/width to other p waves.
What is this?
Supraventricular Tachycardia:
3 or more supraventricular complexes in a row.
What is this?
Supraventricular Atrial Fibrillation
No P waves and baseline is wavy. Irregularly irregular
What is this?
Ventricular Premature Complexes
Wide and bizzare QRST complex which doesn’t usually match P complex:
What is this?
Ventricular Fibrillation
No recognisable QRST Complexes and no baseline
What is wrong with this ECG?
What is this?
Low heart rate
In this case the dysrhtmia is severe and affecting cardiac output so treat it with drugs to make the animal stable whilst you find out the primary cause.
Very low heart rate: lots of P waves and only a few QRS complexes. Very low ventricular rate.
What is wrong here?
Very fast heart rate
Very fast heart rate. Heart will fail if it beats that fast and ventricles do not have time to fill.
What is wrong here?
Fast Ventricular tachycardia
Near to death with a heart rate this fast. No normal complexes. Can lead to ventricular fibrillation and death.
