2.2.1 Electrocardiography Flashcards
Which leads are responsible for capturing the horizontal planes?
Pre-cordial
79 y/0 F with severe dyspnea: note the tachycardia.
Describe the rate, rhythm, and axis? What could this patient be experiencing?
Rate: just under 150
Rhythm: Irregular rhythm
Axis: Right axis deviation
Representation of Atrial fibrillation
- almost always tachycardia
- w/ irregular rhythm
In which lead, is the Q wave normally found?
AVR lead (210 degrees)
What type of block?
Complete heart block/3rd degree
How would infarction manifest itself on an EKG? Ischemia?
Infarction: ST segment elevation
Ischemia: ST segment depression
Where does phase 2 of the cardiomyocyte AP show up on an EKG?
It forms the separation b/t the S and T wave
What is happening in the heart during the QRS complex?
Ventricular depolarization (contraction)
Altering phase 3 of the cardiomyocyte AP will affect what on an EKG?
Alter the shape of the T wave
What type of axis deviation would be found in a patient that presented with the following EKG readings?
Normal mean electrical axis, two thumbs up
Still looking at axis, a R wave that points up is considered what? downward?
Upward: positive
Downward: negative
Which leads are responsible for catching the frontal plane?
Limb
60 yF with chest pain
Infarction
What type of AV block?
2nd degree AV block Mobitz type I
What the three possible criteria to use when determining whether the patient has hypertrophy? Describe the sensitivity and specificity of these.
Romhilt Estes, Cornell, No name criteria
All poorly sensitive but very specific
What type of axis deviation would be found in a patient that presented with the following EKG readings?
Right axis deviation
Rapid review: What happens during phases 0-4 of a cardiac myocyte action potential?
What is occuring in the heart during the P wave?
Atrial depolarization (contraction)
What are the four types of AV block? What are their characteristics
What is occurring in the cardiac tissue during the ST segment?
Ventricles are the plateau phase of depolarization (phase 2)
What is happening in the heart during the T wave?
Ventricular repolarization (relaxation)
What is this patient’s HR? What else do you notice about this EKG?
300/5 = 60
Lack of P wave (not SA node pacing). Could be AV nodal pacing (almost brachycardia)
What type of axis deviation would be found in a patient that presented with the following EKG readings?
Extreme right axis deviation
36 y/o F with syncopal episode
Describe rate, rhythm, axis, and hypertrophy.
Rate: Just under 60
Rhythm: Sinus (Lead I and II are good for finding p wave due to placement over atria)
Axis: Normal
Hypertrophy: present
Describe the placement of the limb leads and the angles of the vectors that they detect?
Einthoven’s Triangle
When analyzing axis, which leads are you looking at? What is considered normal?
Lead I and AVF; anything between 0 and 90 degrees
Which leads are good for looking at ST elevation?
II, III, aVF
What is the treatment for A fib/right axis deviation?
Control HR, consider anticoagulation (CHADS2) to reduce the risk of stoke/thromboembolism
What are the 6 steps in the clinical approach to reading an EKG?
- Rate
- Rhythm
- Axis
- Intervals
- Hypertrophy
- Ischemia/Infarction
What is occurring the cardiac tissue when the QRS complex begins?
Conduction through the His-Purkinje system and ventricular system
When looking at rhythm, what is the first question to ask yourself?
Is it sinus or not? (presence of the P wave?)
What is the Cornell calculation for ventricular hypertrophy?
RAVL + SV3 = 20 (in females)
RAVL + SV3 = 28 (in males)
Gender bias is due to the fact that female breast tissue doesn’t conduct electrical impulses as well as muscle
Describe the four possible axial scenarios and the direction of the R wave in leads I and aVF.
Normal: positive R wave for both
Right axis deviation (R.A.D.): positive aVF and negative Lead I
Left axis deviation (L.A.D.): negative aVF and positive Lead I
Extreme R.A.D: negative aVF and Lead I (in healthy individual, possibly situs inversus)
How does one determine the rate when looking at an EKG?
Each big box is 300.
So, find two consecutive R-R peaks and count the number of boxes between them. Then, take 300 and divided by the number of boxes that you just counted.
What is the most common cause of L ventricular hypertrophy? What are some other possible causes?
Chronic HTN
Other causes: aortic stenosis, HOCM
An obstruction (due to MI or surgical cut) of the left bundle branch will have what effect on the QRS complex?
Wider due to slower propogation through the ventricle
- Called a left bundle branch block
What type of axis deviation would be found in a patient that presented with the following EKG readings?
Left axis deviation
What is responsible for the P-R interval found on an EKG?
The pause in the AV node
