3.2.10 Electrocardiograms (ECGs) Flashcards
Electrocardiograms (ECGs)
Electrocardiography can be used to monitor and investigate the electrical activity of the heart
Electrodes that are capable of detecting electrical signals are placed on the skin
These electrodes produce an electrode cardiogram (ECG)
An ECG shows a number of distinctive electrical waves produced by the activity of the heart
A healthy heart produces a distinctive shape in an ECG
EGC Key Features
use along side corresponding paper flashcard
The P Wave
- caused by the depolarisation of the atria, which results in atrial contraction (systole)
The QRS Complex
- caused by the depolarisation of the ventricles, which results in ventricular contraction (systole)
- this is the largest wave because the ventricles have the largest muscle mass
The T Wave
- caused by the repolarisation of the ventricles, which results in ventricular relaxation (diastole)
The U Wave
- scientists are still uncertain of the causes of the U wave
- some think it is caused by the repolarisation of the Purkyne fibres
Using ECGs to Diagnose Heart Problems
If someone has a suspected heart problem, a doctor will often use an ECG as a diagnostic tool
Some heart problems produce certain shapes or ways in an ECG which allow for a diagnosis
Tachycardia
When the heart beats too fast, it is tachycardic
An individual with a resting heart rate of over 100 bpm is said to have tachycardia
Bradycardia
When the heart beats too slow, it is bradycardic
An individual with a resting heart rate below 60pm is said to have bradycardia
A lot of fit individuals or athletes tend to have lower heart rates and it is usually not dangerous
Ectopic Heartbeat
This condition is caused by an early heartbeat, followed by a pause
It is common in the population and usually requires no treatment, unless it is very severe
Fibrillation
An irregular heartbeat will disrupt the rhythm of the heart
Severe cases of fibrillation can be very dangerous, even fatal
