ECG Flashcards
describe what we are recording in the ECG
electrical activity of the heart
- the wave of depolarisation travels from the SAN through the atria, then goes ot the AVN, then it travels through the bundle of Left bundle His , then the RIGHT bundle of His, then the purkinje fibres
what acts as a skeleton to the heart? describe it
- ANNULUS FIBROSIS
- 4 fibrous rings around ;
- pulmonary valve
- aortic valve
- Right atrioventricular
- Left atrioventricular
describe the cellular charges changes and how this is marked in an ECG
- ECG is a positive electrode
- initially at rest the cell is more positive outside than inside, this is due ot the cell being more permeable to the potassium than sodium, alothough theyare both positively charged NA+ carries a stronger positive charge than potassium, so more positive outside than inside
- then we enter depolarisation , the sodium moves from outside to inside the cell, this makes the inside positive and the outside negative
- the wave of depolarisation travels through the myocytes from the SAN to the apex of the heart, this is movement of negative wave towards the electrode at LIMB LEAD 2, hence why it is registered as a positive deflection
what are the limb leads , draw them
what are the onducting systems of the heart and which takes over when
- SAN - natural autonomaty , intrinsi rate of 60-100
- AVN - only if SAN is firing, on the ECG you’d see that the rate is slower and theres no sinus rhythm 40-60bpm
- ventricular myocytes - fire very slowly at 20-40 bpm
draw and label the ECG pattern normal one and the length of each phase
p = atrial depolarisation 0.12-0.2
pr segment = 0.12-0.2
qrs = ventricular depolarisation
describe what the parts of each segment on ECG represents and how long they last
- p = atrial depolarisation
- PT segment =
- represents the time it takes for ventricles to fill
- it acts as an isoelectric line
- lasts 0.12-0.2 seconds (3-5 small bxes)
- Q = as the muscle in the interventricular septum depolarises from the left to the right
- there can be a small downward deflection as the wave of electrical acitivity is moving to the sides and so away from the electrode and not towards it
- R = depolarisation of the apex of the heart and free ventricular walls, large due to the larger muscle mass, so if there was left sided hypertrophy then it would be larger
- S = depolarisation upwards to the bases of the heart,
- negative due to the electrical activity moving away from the heart
- T = repolarisation of the ventricles ,
- positive deflection because of the replusion of the electrical current since becomes more positive as NA+ moves out
- also theres a driving force away from the electrode and towards the SAN and begins at the epicardial surface of apex of heart
first downward deflection after the P wave
Q wc is a result of the electrical activity moving sideways as it depolarises the left and right muscles
how do you calculate the HR of a regular ECG and irregular ECG
regular = peak from one R to next R e.g 4 big squares then do 300/4 = 75bpm
irregular count large 30 SQUARES a dn how many peaks there are in those squares, then x10
where do you put the chest leads and what are they called?
precordial chest leads
- V1 =. right strenum ridge 4th intercostal space = gives anteroseptal right view
- V2 = left strenum ridge 4th intercostal space = gives anteroseptal left view
- V3 = inbetween V2 and V3 = gives anterior apex view of lV and RV
- V4 = 5th intercostal space midclavicular line =gives anterior apex wall of Rv and LV
- V5= 5th intercostal space anterior axilllary line = gives lateral LV view
- V6= 5th intercostal space midaxillary line = gives lateral LV view of heart
what view and artery can supplies the rejoin of view of the precordial leads and limb leads
- V1= anteroseptal RV = LAD
- V2 = anteroseptal LV = LAD
- V3 = distal lad anteroapical view
- V4 = LAD anteroapical (apex of RV and LV)
- V5 = circumflex
- V6= circumflex +proximal LCA
- limb lead I= proximal LCA and circumflex
- limb lead II = RCA inferior aspect of heart
- limb lead III = RCA inferior aspect
- AvF= RCA inferior view
- AvL= circumflex and proximal LCA anteriolateral
- AvR = / /
necrosis of the right wall? wc leads
II, III, AvF
occlusion of LADwc leads?
V1 V2 V3 V4
damage to left wall
AvL, V5 V6 L1 (bold = best at looking at left side of heart
damage to posterior aspect of heart, wc lead?
R wave would be taller and peaked more than in V1 V2 because posterior aspect of heart supplied by RCA
but not always the case
draw a whole ecg script and label wc parts have wc artery and view
V1 V2 septal (RCA)
V3 V4 anterioapical (apex of LV and RV, LAD)
V5 V6 (anterolateral -proxmial LCA and circumflex artery)
L1 = RCA wave of left lateral
L2 = RCA e activity from atria to apex
L3 = inferior aspect RCA
AvR = / artery
AVL= similar to L2 but opposite side,
AvF= inferior asepect
