ECG (Practical 2) Flashcards
What does the ECG signal measure?
The voltage difference between 2 electrodes from the skin surface
What happens to the ECG signal when the red clip is not attached to the electrode?
There is no signal recorded
What direction does the wave of excitation (cardiac vector) normally travel through the heart?
Top right to bottom left
Which factors can influence the amplitude of the ECG signal?
- size of the muscle
- direction of the cardiac vector
What does the P waveform represent?
Atrial depolarisation
Why is the R wave amplitude larger than the P wave?
The R wave represents ventricular contraction
What is the normal duration of the QRS complex?
0.08 seconds
Approximately at what point during the ECG signal would the second heart sound (dupp) occur?
After the T waveform
Which of the ECG waveforms are most likely to indicate heart rate?
QRS complex
How does forced expiration influence the ECG signal?
The QRS amplitude is larger compared to resting ECG
How does deep inspiration influence the ECG signal?
The QRS amplitude is smaller compared to resting ECG
Why does deep inspiration influence the ECG signal?
Position of the cardiac vector is changed by expansion of the chest
How does atrial fibrillation change the ECG?
P wave disappears
How does ventricular fibrillation change the ECG?
There is no clear rhythm
What happens to the ECG signal if a patient has high blood potassium levels?
The amplitude of the T wave is larger
