Cardiac Interpretation Flashcards
Order of the electrical conduction system of heart
SA node → inter-nodal pathways → AV node → Bundle of His → L + R bundle branches → Purkinje fibers
12 Lead EKG and views
- 10 electrodes used → 12 different perspectives
- Limb leads - Vertical view
- RA, LA, RL (neutral or grounding lead), LL
- Precordial Leads - Horizontal view
- V1 to V6
- Chest
5 different views of heart (sections)
- Anterior wall
- Inferior wall
- Lateral wall
- Posterior wall
- Septal wall
Limb leads + where each lead is placed? How is each lead read (L → R)
which one is the neutral lead?
- Einthoven’s triangle
- Limb leads - VERTICAL VIEW
- RA, LA, RL (grounding lead), LL
- Lead 1: R arm → L arm
- Lead 2: R arm → L leg
- Lead 3: L arm → L Leg
Reads negative → positive
Which limb lead corresponds to which part of the heart?
- STANDARD LIMB LEADS
- I: R arm → L arm - lateral wall
- II R arm → L leg - inferior wall
- III L arm → L leg - inferior wall
Augmented Limb Leads view
- AVR - junk lead, non-specific view
- AVL - lateral wall
- AVF - inferior wall
Limb leads cheat sheet chart
aVR - square root of SQUAT
Precordial lead placement
Which view in general vs Limb lead view?
- Limb leads → vertical view
- Precordial leads → horizontal view
Views of heart on EKG - Precordial Leads (chart)
Again, LOOKING AT HORIZONTAL PLANE
Views of heart on EKG
*Contiguous leads*
Limb leads and chest leads together
Contiguous leads (slide 12)
EKG waveforms: P wave
What does it indicate when this wave is abnormal?
- Atrial DEpolarization (contraction)
- Starts in SA node
- P wave absent or abnormal - atria malfunction
EKG wave forms: QRS complex
What does it indicate when this wave is abnormal?
- Ventricular DEpolarization
- Atrial REpolarization
- Abnormal → ventricular issue
EKG wave forms: T wave
What does it indicate when this wave is abnormal?
- Ventricular repolarization
- Same - heart has trouble relaxing and filling with blood - diastole issue
Isoelectric line
Considered baseline
EKG waveforms should ALWAYS return to straight and flat level in between complexes
What makes a wave positive or negative?
- A wave of electrical depolarization moves parallel to the direction of a lead.
- If it moves towards the (+) pole of the lead, a (+) deflection occurs on the EKG.
- If it moves away from the (+) lead, towards the (-) pole of the lead, a (-) deflection occurs onEKG.
- Positive wave form → goes up from isoelectric line
- (-) lead → (+) lead
- Negative wave form → goes down from isoelectric line
- (+) lead → (-) lead
What does Lead II mimic?
- REMEMBER: LEAD II = R ARM → L LEG li>
- Trajectory mimics the natural conduction system of the heart (impulse/conduction of heart)
What is the Axis of the heart?
Overall direction of the electrical activity of the heart
What is the correct positioning of the axis?
Should be downward and to the left
Between -30 and +90 degrees
What does it indicate if the axis is deviated?
Think about the Axis chart of positives and negatives!
If axis is deviated, it can indicate various problems such as hypertrophy, BB, tissue damage, conduction abnormalities
Positive = above isoelectric line
Negative = below isoelectric line
RAD = R axis deviation
LAD = left axis deviation
Easiest way to determine axis? Which leads would you look at?
Look at Leads I (R arm → L arm) and aVF (interior portion of LV)
EKG graph paper, what two things does it measure?
Time (rate) - horizontal line
Amplitude (voltage) - vertical line
EKG squares = what numbers?
- Horizontal:
- 1 small square = 0.04s (40msec)
- 1 Large square = 0.2s (200msec)
- 5 Large squares = 1s (1000msec)
- Vertical:
- 1 small square = 1mm (0.01mV)
- 1 Large square = 5mm (0.5mV)
- 2 Large squares = 1mV
Steps to reading EKG
- Rate
- Rhythm: regular or irregular
- Does it look uniform? P wave present?
- Intervals? PR, QRS
- Basic rhythm/origin
-
Hypertrophy
- For now concentrate on ventricular
- ST segment abnormalities
