the normal ECG Flashcards
what is an ECG
a time voltage graph o electrical conduction through the heart
what kind of cells does an ECG record
myocardial cells as they are on the surface
what is needed to record pacemaker cells activity
intracardial ECG
what produces a positive reading on the ECG
movement of current towards the sensor
what doe gap junctions allow cardio myocytes to do?
rapid impulse transmission from cell to cell
what does the p wave indicate?
atrial depolarisation
what does the PR interval indicate
time for the impulse to leave the SAN, travel through the atria, reach the AVN and start depolarising the ventricles - the majority of this time is spent in the AVN to allow for ventricular filling
what does the ST segment indicate?
isoelectric portion - the time from ventricular depolarisation to repolarisation
what does the QT interval indicate
the time from ventricular depolarisation to repolarisation
why is atrial repolarisation not seen?
it is slow and diffuse
what leads is the T wave normally negative in?
aVR, V1
which are the bipolar leads
I, II, III
which are the augmented limb leads
aVR, aVL, aVF
which are the chest leads
V1-V6
what leads show the inferior aspect of the heart
II, III, aVF
what leads show the anterior aspect of the heart
V1-V6
what leads show the lateral aspect of the heart
V5, V6, I, aVL
what does left axis deviation indicate
LV hypertrophy or conduction defecit
what does right axis deviation indicate
RV hypertrophy
right axis deviation on an ECG
I -ve QRS, II +ve QRS
left axis deviation on an ECG
I +ve QRS, II -ve QRS
what leads does the R coronary artery relate to?
II, III, aVF (inf)
what leads does the L anterior descending artery relate to?
V1,V1 (septal, ant)
what leads does the L anterior descending artery relate to?
V3, V4 (ant)
