ECG Fundamentals and NSR Flashcards
What are the atrioventricular valves?
- Tricuspid
- mitral
What are the semi-lunar valves?
- Pulmonary
- Aortic
Define “Diastole”.
Relaxation
Define “Systole”
Contraction
What is the electrical conduction pathway?
SAN - AVN - Bundle of his - Bundle branches - Purkinje fibers
What is a septum?
The part that separates 2 chambers
What does the cardiac skeleton consist of?
4 cartilage rings around the valves to provide structure of the heart.
What are the 4 functions of cardiac myocites?
Autonomy = Ability to spontaneously initiate
Excitability = Ability to respond to a signal
Conductivity = Ability to transmit signals
Contractility = Ability to contract after depolarisation
Define “natural pacemaker”.
A cluster of cells within the heart that have the ability to cause a contraction.
What does the vagus nerve do to the SA node?
Releases a hormone to slow down the electrical conductive pathway, to lower blood pressure.
Which cranial nerves are involved with the control of blood pressure?
Vagus nerve
Glossophargengeal
When Sino Atrial node is being used as a natural pacemaker, what is the rate it is likely to beat at?
60-100
When Atrial cells is being used as a natural pacemaker, what is the rate it is likely to beat at?
55-60
When Atrioventricular node is being used as a natural pacemaker, what is the rate it is likely to beat at?
45-50
When Bundle of his is being used as a natural pacemaker, what is the rate it is likely to beat at?
40-45
When Bundle branches is being used as a natural pacemaker, what is the rate it is likely to beat at?
40-45
When Purkinje fibers is being used as a natural pacemaker, what is the rate it is likely to beat at?
35-40
When Myocites is being used as a natural pacemaker, what is the rate it is likely to beat at?
30-35
What are the 3 main ions that cause contraction in myocytes?
- Calcium
- Potassium
- Sodium
At what voltage does a cell sit at during the resting period?
-90 mV
What is the main ion inside the cell during the resting period?
Potassium
Which ion can easily pass through the membrane?
Potassium
What is the threshold?
The voltage in which sodium potassium pumps are activated, triggering depolarisation of the cell.
Which ions move through a voltage gated channel?
Calcium - During deplorisation
Sodium - During depolarisation
Potassium - During repolarisation
What increases the deflection on an ECG?
An increased number of cardiac myocytes contracting
With every cycle of the sodium-potassium pump, how many of each molecule moved against the concentration gradient?
- 3 sodium
- 2 Potassium
Which 2 polarisation show an upward deflection on an ECG?
Depolarisation towards the ECG electrode
Repolarisation away from the ECG electrode
Which 2 polarisation cause a downward deflection on the ECG?
Repolarisation towards the ECG electrode
Depolarisation away from the ECG electrode
What is a P wave?
A wave of depolarisation from the SAN across the atria
What complex shows ventricular systole?
QRS
How long is shown in 1 large square of ECG paper?
0.2 seconds
How long is shown in 1 small square of ECG paper?
0.04 seconds
What is the standard ECG printer speed?
25mm per second.
What is the expected PR interval?
0.12-0.25 (3-5 small squares)
What should the QRS width be?
1.5- 2.75 small squares (0.06 - 0.11s)
What is the normal QT segment?
0.35 - 0.42s (9-10.5 small squares)
How is heart rate calculated on a ECG3?
Number of QRS complexes on a 6 second rhythm strip
How many large boxes are on a 6 second rhythm strip?
30
What are the 9 points for checking NSR?
- Rate
- Regularity
- What does the P wave look like
- Is there a P before every QRS
- Allways a QRS post P
- Normal PR QT intervals?
- Broad QRS
- Normal ST segment
- Where is the pacemaker
