T5: ECG Flashcards
(41 cards)
What does an electrocardiograph do?
- Monitors heart rate, cardiac rhythym and axis deviation.
- Records electrical activity of the heart.
What does a normal heart contraction require?
Normal electrical conduction of activating electrical impulses through cardiac muscle tissue.
What are ECGs taken for?
- Diagnosing cardiac diseases and abnormal cardiac rhythym (arrythmia)
- Aids in detection of enlaged heart
- Aids in detection of electrolyte, systemic or metabolic disorders
- Anaesthetic monitoring
- Useful in cardiac arrest cases and CPR
- Useful in diagnosing ventricular fibrillation
Where in the heart does deoxygenated blood enter and where does it go?
Right side of heart.
Pumped to lungs.
Where in the heart does oxygenated blood enter and where does it go?
Comes from the lungs and enters left side of heart.
Pumped to the body.
What is a trace?
The recorded electroactivity on heat sensitive paper
What does an ECG represent?
Amplitude and duration of electical activity
What happens in each heart contraction?
Each contraction of the heartis preceded by an electrical wave font that stimulates the heart to contract and relax in preperation for next heart beat.
What is Depolarization?
Contraction of the myocardium
What is Repolarization?
Relaxation of cells after depolarization
What is systole?
Contraction of the ventricals
What is diastole?
The filling of ventricles (relax)
What are the parts to an ECG?
- P Wave
- QRS Interval
- ST/T wave
- PR interval
- QRS Duration
- QT Interval
- RR Interval
- PP interval
Attempt to draw a typical ECG printout.
What does each ECG lead have?
Each lead has a positive and negative pole which is attached to the skin of the animal and can be used to measure the spread of the eclectrical activity within the heart.
Different leads allow you to look at the heart from different angles. Each angle is called a lead.
Describe Alligator Clips
- Good for once off ECGs
- Clips should be placed on loose folds of skin at the elbows and knees.
- Requires a conducting medium (eg spirit) just sufficient enough to wet clip and hair through skin.
Describe ECG pads
- Good for lengthy ECGs eg during surgery
- Can be taped to patient’s feet to provide a ore reliable contact with the skin.
- Gel is required - some pads come with gel
How do you read an ECG Strip?
- ECG paper is a grid where time is measured along the horizontal axis
- Each sml sq is 1mm in length and represents 0.04 secs
- Each lrg sq is 5mm in length and represents 0.2 secs
- Voltage is measured along the vertical axis
- 10mm is equal to 1mV in voltage
How do you measure the heart rate on ECG paper?
- ECG paper moves at a standardized 25mm/sec.
- Vertical lines can be used to measure time.
- There is a 0.20 sec between 2 of the large lines.
- ECG paper usually has special markings every 3 seconds
What should you check before doing an ECG?
- Machine contains enough paper
- Pen is in centre of paper
- Lead clips are clean
- Aqaquete amount of elctrode gel available
- Machine is earthed
What are the 3 basic controls on an ECG machine?
- Paper speed: faster the paper speed the more spread out the heart beat is across page
- Calibration settings: sets the height of the complexes typically Icm/mV
- Filter: can help reduce the impact of artefacts on the recorded trace, but always have it turned off initially.
How would you position a dog and a cat for an ECG reading?
Dog: right lateral recumbancy
Cat: sternal recumbancy
Why do you not want to sedate an animal for an ECG reading?
Sedation, esp with alpha 2 agonists, may alter cardiac rythym
What 4 questions should you ask when trying todetermine if a rhythm is normal or abnormal ?
- Is there a P for every QRS?
- Is there a QRS for every P?
- Are the Ps and QRSs consistently and reasonably related?
- Are the Ps and QRSs all the same?
