Electrophysiology * Flashcards
What is the depolarization sequence?
SA node > AV node > Bundle of His > Left & Right Branches > Purkinje Fibres > Ventricular Fibres
What is the P wave?
It is atrial depolarization/systole.
What is the PR interval?
It’s the beginning of the P wave and goes to the QRS complex. It’s the time it takes for the impulse to go from SA node to the purkinje fibres. It’s the interval of time between atrial and ventricular depolarization.
What is the QRS complex?
It’s ventricular depolarization, (systole) and atrial depolarization (diastole)
What is the ST segment?
It’s the beginning of ventricular depolarization/diastole. It’s the end of the QRS complex, and goes to the beginning of the T wave.
What is the J point?
It’s the end of the QRS complex and beginning of the ST segment.
What is the T wave?
It’s ventricular repolarization/diastole.
What is the QT Interval?
It’s the length of time for ventricular depolarization and repolarization. Begins at Q and ends at the end of T wave. (Longest amount of time)
What are U waves?
Not always present, unless HR is slow. It follows the T wave and is smaller.
What’s the ISOelectric line?
It’s the horizontal line between cardiac cycles.
What is a 12 lead ECG?
It obtains 12 views of the heart.
What does the lead system record?
The differences between left arm, right arm and left leg.
What is lead one?
It’s the result of the difference between right and left arm. It’s the starting point.
What’s lead 2?
Difference between left leg and right arm.
What’s lead three?
Difference between left leg and left arm.
What is Einthoven’s triangle?
It’s the axis of 3 leads forming an equilateral triangle with the heart in the centre. It’s used for HR
What’s aVR?
It’s an augmented limb. It’s a right sided lead. Looks down at the heart from the right shoulder?
What’s aVL?
Left sided lead – lateral lead.
What’s aVF?
In an inferior/perpendicularly
What are precordial leads?
V1-V6. Unipolar leads that are in the transverse/horizontal plane
Where is V1?
It’s at the 4th intercostal space to the right of the sternum.
Where’s V2?
4th intercostal space. Left of sternum
Where’s V3?
Midway between V2 and V4.
Where’s V4?
Midclavicular line – 5th intercostal space.
Where’s V5?
Anterior axillary line. Same level as v4.
Where’s V6!
Midaxillary line. Same level as V4.
What are the inferior leads?
11, 3 and aVF
What are the septal leads?
V1 and V2
What are the anterior leads?
V2 to V4.
What are the lateral leads?
Precordial leads: V4-V6.
High lateral: 1, aVL.
What do 5 large boxes equal?
1 second.
What do 30 large boxes equal?
6 seconds.
What’s the voltage measurement of r?
21 mm
What’s the voltage measure of Q?
4 mm
What’s the voltage measurement of S?
7.5 mm
What’s the R to R cycle?
Ventricular rate
What’s the P to P cycle?
Atrial rate
What’s the 6 s method to calculate heart rate?
Count the number of RRI IN 6 seconds and multiply by 10.
What’s the large box method?
Locate 2 consecutive R waves. Count the number of large boxes between them and divide by 300.
What’s small box method?
Count number of small boxes between 2 R waves and divide into 1500.
What’s the duration between R waves method?
Count the duration in seconds between 2 waves and divide this number into 60.
