ECG generation and interpretation Flashcards
What are cardiomyocytes
cardiac muscle cells
What is responsible for rhythmic pumping of the heart
cardiomyocytes
what is the resting potential of a cardiomyocyte
-90mV
What keeps the cardiomyocyte negative
potassium ions leaving the cells
Dipole
created by equal but opposite charges that are seprated by a short distance
when is the deflection across cells greatest
when recording electrodes at the poles
if both sides of the cell are the same charge what is the potential difference
0
If one side of the cell is positive or negative and the other isn’t, will there be a potential difference
yes
Where do you place the 3 ECG leads
right fore
left fore
left hind
Why do you use 3 leads
you may see something in one lead but not the other
What is the P wave
atrial depolarisation
What is the PQ interval
contraction and relaxation of the atria
What is the QRS wave
ventricular depolarisation
What is the T wave
ventricular depolarisation
Why perform an ECG
assess rate and rhythm of heart
what does ECG mean
electrocardiogram
What does an ECG show
electrical activity of the heart
What can cause artefacts in ECG
interference
movement of the limbs
purring
What is normal sinus rhythm
normal impulse originates in the SAN
What is sinus arrhythmia
rhythm is irregular because the rate increases with respiration
What are dysrhythmias
abnormal heart rhythms
What are bradydysrhythmia’s
low heart rate
What is sinus arrest
Flat line sandwiched between a regular rhythm
What is a fist degree AV block
P wave and QRS complex are normal but the P-R interval is prolonged
What is a second degree AV block
P wave is not conducted through the AV node, a P wave with no QRS
What is a 3rd degree AV block
persistent failure of conduction through AV node, ventricles pace themselves, wide and bizarre escape complexes
What is tachdysrhythmias
high heart rate
what is supraventricular tachydysrythmias
supraventricular premature comlexes, premature P wave interrupts normal P wave rhytm, QRST is usually normal, atrial fibrillation
What is ventricular tachydysrhythmias
ventricular origin, ventricles contract prematurely, wide and bizarre QRST complex
What is MEA
mean electrical axis
Where do you place lead 1
right fore to left fore
Where do you place lead 2
right fore to left hind
Where do you place lead 3
left fore to left hind
a long P wave is suggestive of
left atrial enlargement
a tall P wave is suggestive of
right atrial enlargement
a tall QRS complex is suggestive of
right ventricular enlargement
a wide QRS complex is suggestive of
left ventricular enlargement
what is the mean alectricl axis
represents the predominantdiraction of depolarisation during excitation of the ventricles
What is tachycardia
fast heart rate
What is bradycardia
slow heart rate
In which part of the QRST complex would AV nodal disease be manifested
PQ interval
