Electrocardiogram Flashcards
What is the purpose of a 12 lead ECG?
to get 12 views of the heart and assess cardiac rhythm and diagnose the location, extent, and acuteness of myocardial ischemia and infarction and evaluate changes in activity
What are the electrode locations for the limb leads when taking an ECG?
Right Arm (RA)- infraclavicular fossa medial to the right deltoid Left Arm (LA)- infraclavicular fossa medial of left deltoid Right Leg (RL)- right side of abdomen (ground electrode) Left Leg (LL)- left side of abdomen below rib cage
What are the electrode placements of the chest for precordial leads of an ECG?
V1-4th intercostal space to right of sternum
V2-4th intercostal space to left of sternum
V3- midway between V2 and V4
V4- 5th intercostal space to left of midclavicular line
V5- left anterior axillary line at V4 level
V6- left midaxillary line at V4 and V5 levels
How many bipolar limb leads are there in a 12 lead ECG? How many augmented uni-polar limb leads? How many uni-polar leads?
3 bipolar limb leads
3 augmented uni-polar limb leads
6 uni-polar leads
Where is the positive and negative input for the bipolar limb leads in a 12-lead ECG?
Lead 1: Positive- left arm Negative- Right Arm
Lead 2: Positive- Left Leg Negative- Right Arm
Lead 3: Positive- left leg Negative- Left Arm
Where is the positive and negative input for the augmented uni-polar limb leads in a 12-lead ECG?
aVR: (+) Right Arm (-) Left arm and left leg
aVL: (+) Left Arm (-) right arm and left leg
aVF: (+) Left Leg (-) right arm and left arm
Where is the positive and negative input for the uni-polar precordial leads in a 12-lead ECG?
V1- (+) 4th IC space R of sternum (-) Central Terminal
V2- (+) 4th IC space L of sternum (-) Central Terminal
V3- (+) between V2 and V4 (-) Central Terminal
V4- (+) 5th IC space L of midclavicular line (-) Central Terminal
V5- (+) L ant axillary line at V4 level (-) Central Terminal
V6- (+) L midaxillary line at V4/V5 level (-) Central Terminal
What is the central terminal for the unipolar precordial leads?
the negative or reference input which is composed of a compound electrode formed by electrically combing the output of the LA, RA, and LL electrodes
What does the P wave on an ECG represent?
Atrial depolarization
What does the PR Interval on an ECG represent?
What is the normal duration of the PR interval?
time for atrial depolarization and conduction from the SA node to the AV node.
Normal duration is .12 to .2 seconds
What does the QRS Complex on an ECG represent?
What is the normal duration of the QRS complex?
Ventricular depolarization and atrial repolarization.
Normal Duration is .06 to .1 seconds
What does the QT interval on an ECG represent?
What is the normal duration of the QT interval?
time for both ventricular depolarization and repolarization
Normal Duration is .2-.4 seconds depending on HR
What does the ST Segment on an ECG represent?
Isoelectric period following QRS when the ventricles are depolarized
What does the T wave on an ECG represent?
Ventricular repolarization
What is normal sinus rhythm?
atrial depolarization begins in the SA node and spreads normally through the electrical conduction system with a HR between 60-100 bpm
What is sinus bradycardia?
sinus rhythm with a heart rate less than 60bpm