10 - ECG 1 Flashcards
1
Q
What are different labels of the ECG squares scale?
A
a. 0.5mV
b. 0.2s
c. 0.1mV
d. 0.04s
2
Q
What is the p wave?
A
- electrical signal that stimulates contraction of atria
- atrial systole
3
Q
What is the QRS complex?
A
- electrical signal that stimulates contraction of ventricles
- ventricular systole
4
Q
What is the T wave?
A
elecrical signal that signifies relaxation of ventricles
5
Q
What are the features of cardiac vectors as measured by an ECG?
A
- steepness of line denotes velocity of AP
- downward deflections are towards the anode (-): depolarisation
- upward deflections are towards the cathode (+): repolarisation
- width of deflection denotes event duration
6
Q
What are the different cardiac vectors, their features and position on ECG?
A
- SA node: atrial depolarisation, auto-rhythmic myocytes (P wave)
- AV node: AVN depolarisation, slow transduction, protective (isoelectric)
- bundle of His: rapid conduction, insulated
- bundle branches: septal depolarisation (Q)
- purkinje fibres i: ventricular depolarisation (R)
- purkinje fibres ii: late ventricular depolarisation (S)
- fully depolarised ventricles (isoelectric)
- repolarisation: ventricular repolarisation (T wave)
7
Q
What do LCx, RCA and LAD stand for on an ECG?
A
- left circumflex artery
- right coronary artery
- left anterior descending artery
8
Q
Where are the 6 different electrodes placed on an ECG?
A
- v1: right sternal border, 4th intercostal space
- v2: left sternal border, 4th intercostal space
- v3: halfway between v2 and v4
- v4: mid-clavicular line, 5th intercostal space
- v5: anterior axillary line, level of v4
- v6: mid-axillary line, level of v4
9
Q
What are the different electrode leads, making up Einthoven’s triangle in an ECG?
A
- lead i: right arm (+ve) –> left arm (-ve)
- lead ii: right arm –> left leg
- lead iii: left arm –> left leg
- right leg = reference lead (+ve)
- first electrode of each pair negative
- also have avR, avL and avF
10
Q
How do you calculate the cardiac axis?
A
- lead ii: 60 degrees and aVL: -30 degrees
- calculate lead net deflections for QRS complexes for both leads
- angle = 60 - tan-1(aVL/lead ii)
- normal range = -30 to 90
11
Q
What is defined at left and right axis deviation?
A
- left axis deviation: between +90 and 180
- right axis deviation: between -30 and -90
- look at lead i and aVF to determine deviation
