Basic ECG Concepts
What does the ECG measure?
The electrical activity of the heart.
What does the P-wave represent?
Atrial depolarization.
A rhythm with no P-waves and irregularly irregular R-R intervals is:
A-fib
First-degree AV block shows what hallmark?
Prolonged PR interval.
ST - elevation suggests:
Myocardial injury (possible STEMI).
The purpose of these chambers is to receive blood.
Left atrium and right atrium.
What does a lead represent on an ECG?
A viewpoint of the heart's electrical activity.
What interval measures AV node delay?
The PR interval.
What rhythm has saw-tooth flutter waves?
A-flutter
Mobitz I block is also called:
Wenckebach.
ST depression typically indicates:
Myocardial ischemia.
The right and left sides of the heart are separated by an internal wall of connective tissue called:
Septum.
Which leads make up Einthoven's Triangle?
Leads I, II, III.
What does the QRS complex represent?
Ventricular depolarization.
A wide-complex tachycardia is most likely:
V-tach.
Mobitz II is identified by
Dropped QRS complexes without PR prolongation.
Which leads show inferior wall MI?
II, III, aVF.
The walls of the heart are made up of three tissue layers.
The endocardium, myocardium, and epicardium.
What is the standard ECG paper speed?
25 mm/sec.
What is the normal duration of a QRS complex?
Less than 0.12 seconds
What rhythm presents with chaotic ventricular activity and no organized QRS?
V-Flutter.
Complete heart block features:
Atria and ventricles beating independently.
Which ECG sign is classic for pericarditis?
Diffuse ST elevation with PR depression.
When the cardiac muscle is relaxed, the calcium channels are _.
Closed.
What is the normal amplitude of a standard calibration box?
10 mm = 1 mV.
The QT interval should be corrected for heart rate using what formula?
Bazett's formula.
Which arrhythmia originates from the AV junction with narrow QRS & a rate of 150-250 bpm?
SVT.
Left bundle branch block has what classic finding in V6?
Broad, notched ("M-shaped") R waves.
Reciprocal changes in STEMI are important because they:
Confirm the diagnosis of acute MI.
What does the release of norepinephrine result in as far as predictable outcomes?
Increased force of contraction
Increased HR
Increased BP