Electrocardiograms PCM and Newman Flashcards
What are the Lateral Leads?
• what artery does this correspond to?
I, aVL, V5, V6
• Circumflex Artery
What are the Inferior Leads?
• what artery does this correspond to?
II, III, aVF
• Right Coronary
What are the Left Anterior Descending Leads?
V1, V2 Septal/Anterior Leads
• Left Anterior Descending Coronary
What are the 2 major causes of QRS widening?
- Bundle Branch Block
* Ventricular Origin of Beat
How would you differentiate between the 2 major causes of QRS widening?
Bundle Branch Block will have RABBIT EARS in V2 and V3, you will also still have a P wave in BBB
• Ventricular Origin of Beat = no rabbit ears
What are 2 possibilities for pathology if you see a P wave before a widened QRS?
• BBB (bundle branch block) or 3rd degree heart block
What causes the Rabbit Ear Appearance on EKG?
Right and Left Ventricle are depolarizing at different times so you have 2 QRS complexes Overlapping
How do you determine between a Right or Left Bundle Branch Block?
Right Bundle Branch
• Rabbit ears in V1 or V2 (septal electrodes)
Left Bundle Branch
• Rabbit ears in V5 or V6
What if you take an EKG on a patient that comes in with chest pain and its normal, then 30 minutes later you re-do the EKG and see Rabbit ears in V5 or V6?
- the Patient has had a STEMI
What if QRS is widened but you don’t see any other abnormalities?
• Intraventricular Conduction Delay (IVCD)
What is commonly seen on the EKG in ischemia?
- ST segment Depression (2 little boxes down)
* T wave inversion
What is commonly seen on the EKG with Injury rather than ISCHEMIA?
- ST ELEVATION (not depression like with ischemia)
- T wave HYPERTROPHY (not inversion with ischemia)
If you see T go all the way until it becomes flat then comes back down this is called Tombstone T waves
How can you tell ST elevation in a healthy individual from one in someone that was having an MI?
In II you will see a wave with a DOWNWARD convexity (frowning)
What do you see in actual INFARCTION?
• HUGE Q WAVES that are 1/3 size of the overall QRS complex
What is the most important factor to take into account anytime your looking at an ECG?
Clinical Context
How do you find rate off of an ECG?
300 / (Number of LARGE boxes between QRS)
How do you determine sinus rhythm?
- Look in lead II and Make sure P-wave is upright
- Find Rate (less than 60 = brady, greater than 150 = tachy)
**Sinus arrythmia between 60 and 100 is normal
What are some reasons that you might have a NARROW QRS complex in a SUPRAVENTICULAR rhythm?
- Atrial Fibrillation (irregularly irregular)
- Atrial Flutter (irregularly irregular)
- PSVT (paroxysmal supraventricular tachycardia)
How differentiate atrial and ventricular rhythms?
Atrial Rhythm = Narrow QRS complex
Ventricular Rhythm = Wide QRS complex (greater than or equal to 120 msec)
What characterizes Ventricular Tachycardia?
• Fibrillation
- A wide QRS with a rate greater than 120
* Fibrillation has no organization to it
What is the PR interval most useful for?
*Key to determining 1st, 2nd, or 3rd degree (Mobitz) atrioventricular block
What happens in Mobitz type I?
PR interval gradually increases until the QRS is dropped
What happens in Mobitz type II?
PR interval is CONSTANT but the QRS complex is still dropped
What happens in Mobitz type III?
Atrial and Venticular Rhythms are completely independent of each other
What is the QRS interval useful for that the PR interval isn’t?
PR - good to determine heart Block
QRS - good to determine BUNDLE block
What are some possible problems that could cause the QRS interval to exceed 120?
- Bundle Branch Block
- Abnormal Ventricular Beat (like PVC)
- Ventricular Rhythm
What does a prolonged QT interval tell you?
• how long should the QT interval be?
That there is a Delay in Repolarization
• QT interval should be less than half of the RR interval (at normal rates btwn 60 and 100)
How does ischemia typically show up on an ECG?
ST depression and/or T-wave inversion
How does Injury typically show up on an ECG?
ST-elevation or Tombstone T waves
How does infarct show up on an ECG?
Q waves are a minimum of one small box wide and are 1/4 to 1/3 height of R waves (BIG Q waves)
Where would you expect an infarct of LAD to show up?
V1-V4 - this makes sense because LAD supplies the Left Ventricle which makes up most of the front wall of the heart
Where would you expect an RCA infarct to show up?
II, III, and aVF - these are the inferior nodes and the bottom/back part of the heart is mostly Right Atria supplied by the RCA
Where would you expect an Circumflex infarct to show up?
I and aVL
