ECG Acquisition Theory Flashcards
When was the ECG first developed?
Early 20th Century
What does an ECG look at?
- Heart rate
-heart rhythm - electrical impulses
-spread of electrical activity
What is the P wave in an ECG?
The P wave is Atrial depolarization, it represents the electrical impulses that causes the atria (upper heart chambers) to contract (depolarize) - which pushes blood into the ventricles. The P wave appears as a small upward deflection in the ECG trace.
What is the QRS complex in an ECG?
The QRS complex is ventricular depolarization. It’s the most prominent part of an ECG. It shows the ELECTRICAL IMPULSES AS IT TRAVELS THROUGH THE VENTRICLES (lower heart chambers). Causing them to contract and pump blood to the lungs and the rest of the body. The QRS complex is typically sharp and tall; a small downward deflection (Q), a large upward spike (R), and a downward deflection (S).
What is the T wave on an ECG?
after ventricular contraction, they must reset in preparation for the next beat. This process is called re polarization and it shows up as the T wave; usually a small, rounded, upward deflection following the QRS complex.
What is the PR interval?
It is the time between the start of the P wave and the start of the QRS complex. It represents the time taken for the electrical impulse to travel from the atria to the ventricles through the AV node and the bundle of his.
What might a prolonged PR interval indicate?
it may indicate delayed conduction, which is potentially a sign of heart block.
What is the QT interval on an ECG?
it is the time taken for the ventricles to depolarize (contract) and then re polarize (reset)
What does a prolonged QT interval indicate?
may indicate a risk for dangerous arrhythmia’s , such as Torsades de pointes.
What is the ST segment on an ECG?
It is the flat section between the end of the QRS complex and the beginning of the T wave. It represents the time when the ventricles are contracting and emptying (but not yet re polarizing.
What can elevation or depression of the ST segment indicate?
Heart attack = ST elevation
ischemia = ST depression
How does an ECG measure heart rate?
The time between successive R waves (peak of QRS complex) enables heart rate to be measured . It also shows if the heart rate is irregular by looking at the intervals between these waves.
What can the amplitude of Waves on an ECG indicate?
High P wave = potential atrial enlargement
Tall or deep QRS complex = potential ventricular hypertrophy.
What are electrodes on an ECG machine?
small sensors that are placed on specific parts of the skin (arms, legs and chest). They detect the tiny electrical impulses generated by the heart.
What is artifact on an ECG? What are the potential reasons for artifact on an ECG?
misleading data on an ECG, not caused by the hearts electrical activity. Reasons this can occur includes:
-movement
-phones
-medical equipment
-electrode placement (loose electrode)
