Cardio Intro (Cardio 1) Flashcards
Path of Blood Flow Through the Heart
SVC and IVC –> right atrium –> right ventricle –> pulmonary trunk/arteries –> lungs –> pulmonary veins –> left atrium –> left ventricle
Sequence of Electrical Activity of Heart
- SA node produces signal that causes atria to contract
- signal reaches AV node
- Bundle of His
- Purkinje fibers
- ventricles contract
EKG/ECG
recording of the electrical activity of the heart
What is an EKG machine reading?
the change in polarity/electrical activity in the heart
12 Lead
- 12 “pictures” of the heart to get a “3D rendering” of the heart on a piece of paper
- only use 10 leads, but get 12 views
- always looks at electrical movement from negative to positive
What are the types of leads?
- 6 limb leads: 3 simple/standard and 3 augmented
- 6 precordial leads (chest)
Lead I
electrical movement from right arm (-) to left arm (+)
Lead II
electrical movement from R arm (-) to left leg (+)
What is the most monitored lead and why?
- lead II
- it shows how the electricity is supposed to move through the heart normally
Lead III
movement from left arm (-) to left leg (+)
Lead aVR
movement from the left arm and left leg to the right arm (+)
**the only lead where the R arm is positive!
Lead aVL
movement from right arm and left leg to left arm (+)
similar to lead I (goes to a positive at the left arm)
Lead aVF
movement from the arms to the left leg (+)
similar to lead II (goes to a positive at the left leg)
Positive Deflection
-an upward spike on the EKG when electrical activity moves toward a positive lead
Negative Deflection
-a downward spike on the EKG when electrical activity moves away from a positive lead
P Wave
atrial DEpolarization
QRS
ventricular DEpolarization
-also hides the atrial repolarization
T Wave
ventricular REpolarization
PR Interval
time from the start of atrial depolarization (P wave) to the start of ventricular depolarization
ST Segment
time between end of ventricular depolarization to start of ventricular repolarization
What does depolarization do to heart muscle?
stimulates it to contract
Which heart structure has more electrical changes/depolarization and why?
the ventricles b/c they have more muscle mass
What is on the horizontal axis of an EKG?
time
What is on the vertical axis of an EKG?
voltage/electrical activity
- What is the width of one small box on an EKG?
2. Large box?
- 0.04 seconds (1 mm)
2. 0.2 seconds (5 mm)
- What is the height of one small box on an EKG?
2. Large box?
- 0.1 mV or 1 mm
2. 0.5 mV or 5 mm
In the circle of axes/quadrant system, what 2 leads are you looking at?
lead I and lead aVF
In the circle of axes/quadrant system, which quadrant has both leads negative?
What does this represent?
- upper right quadrant (of the pt, so it’s opposite of on a paper)
- extreme right axis deviation, aka no man’s land
In the circle of axes/quadrant system, which quadrant has both leads positive?
What does this represent?
- lower left quadrant
2. this quadrant is normal and where you would expect the heart’s electrical vector to be
In the circle of axes/quadrant system, which quadrant has lead I POSITIVE and aVF NEGATIVE?
What does this represent?
- upper left quadrant
2. left axis deviation LAD
In the circle of axes/quadrant system, which quadrant has lead I NEGATIVE and aVF POSITIVE?
What does this represent?
- lower right quadrant
2. right axis deviation RAD
Causes of LAD
- left anterior hemiblock: electrical activity blocked from passing through His bundle
- Q waves of inferior MI
- artificial cardiac pacing
- emphysema
- hyperkalemia
- Wolff Parkinson White syndrome
- tricuspid atresia
- injection of contrast into left coronary artery
Is left ventricular hypertrophy cause left axis deviation?
NO!
they can be correlated, but not always
Causes of RAD
- normal finding in kids and tall thin adults (heart sits more up and down than tilted
- right ventricular hypertrophy
- chronic lung dz
- anterolateral MI
- left posterior hemiblock
- pulmonary embolus
- Wolff Parkinson White syndrome
- atrial or ventricular septal defect
Causes of Extreme RAD
- emphysema
- hyperkalemia
- lead transposition (most common!)
- artificial cardiac pacing
- ventricular tachycardia
Steps 1, 2 and 3 of EKG Interpretation
- regular or irregular
- fast, slow, normal
- what is the rate (bpm)
Steps 4 and 5 of EKG Interpretation
- is there a P with every QRS (find each QRS then check for P)
- is there a QRS with every P (find each P then check for QRS)
**if one or both of these answer NO, then look for weird/extra beats!!!
Steps 6 and 7 of EKG Interpretation
- what is the PR interval
7. what is the width of the QRS complex
Step 8 of EKG interpretation
- what is the rhythm (eg normal sinus rhythm)
Steps 9, 10, 11 of EKG Interpretation
- what is the axis
- are there any funny or extra beats (if so, what are they and why)
- any other changes: ST, T or Q wave changes; indication of hypertrophy, etc
What is a normal PR interval?
.12 - .20 seconds (3-5 little boxes or w/in one large box)
What is a normal QRS width?
.08 - .12 seconds (2-3 little boxes)
