Flashcards in Cardiac function measurements Deck (29):
What is a doppler electrocardiography?
Measures and visualizes the speed and direction of blood flow
- Red= hot=towards
-Blue= cold= away from
What is a normal ejection fraction?
55% and above
Increase or decrease in contractibility leads to downward shift of ESPVR line? Name a cause
Decreased contractibility causes by heart disease
How would a vasoconstrictor affect the ESPVR line?
increases after load and thus increase contractibility
What is Fick's principle?
Calculates the rate at which a substance is being added to or removed from the blood as it passes through an organ
What is the most accurate measurement of CO? What else is this good for?
Using Fick's Principle
Tissue metabolism as well
What is a cardiac index?
Cardiac output/Body surface area
- use the Namogram scale using weight and height
What does the P wave represent?
What does the flat line between the P wave and QRS complex mean?
Pause that allows the ventricles to fill
What is the QRS complex represent?
What does the ST segment represent? What is responsible for this?
Plateau phase of ventricular AP
What does the PR interval represent?
Conduction time through the atria and AV node
What does the QT interval represent?
Total time of ventricular systole
What do the smallest boxes on an EKG represent in time?
What does 1 large box represent?
In Einthoven's Triangle where are the leads?
RA- both neg
LA- One neg one positive
LL- Both pos
Where are leads 1,2 and 3?
1. RA to LA
2. RA to LL
3. LA to LL
What doe positive and negative inflections of the EKG represent?
1. pos- moving toward a positive charge
2. moving away from a pos charge
Where does the depolarization begin of the QRS complex?
Left intra-ventricular septum
Why does the T wave a repolarization effect have a positive inflection on EKG?
Negative wavefront moving away from positive charge (towards negative). Thus double negative making a positive wave form
What is the mean electrical axis?
The orientation of the Cardiac dipole during the most intense phase of ventricular depolarization
What are normal, left and right axis deviations?
-30-90 degrees= normal
90= right axis deviation
Which lead should have the largest R wave?
What are Augmented leads?
For 6 lead EKG
- Named for the physical location on the body voltage recording the + pole
What are aVR,aVL and aVF? What are their perpendiculars?
aVR- Starts RA and 3
aVL- Start LA and 2
aVF- Start LL and 1
What are the degrees of the a 6 lead EKG?
How does one calculate the mean electrical axis?
1. Calculate by finding largest R wave and this is your dipole. If wave is negative then its 180 degrees of dipole
2. Determine lead that is most equiphasic QRS complex. Which lead is 90 degrees away from that
What is the limit of the 6 lead EKG? What solves this?
6 lead is 2d. If you want 3d view you need a 12 lead.