Introduction to EKGs Flashcards
The ___ dominates the visual view while the ___ dominates the electrical view
RV, LV
The heart is in the ____ of the sternum
Lower 1/2
Blood contains
RBCs, WBCs, Platelets, Plasma
Describe the direction of blood flow
Vena Cava, Right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein, left atrium, left ventricle, aorta, body, repeat
The atria have ____ walls while the ventricles are ____ walled
Thin, Thick
How much atrial blood flow is passive?
80%
What are valves made of
dense CT and endocardium
Purpose of the valves
Prevent backflow
The right AV valve is called the
Tricuspid valve
The left AV valve is called the
Mitral or bicuspid valve
The first phase of the cardiac cycle is
Diastolic filling
The active phase of the heart is called
Systole
How many layers does the pericardium have
Three. The fibrous, Serous, and Pericardial
The heart wall is comprised of
Epicardium, Myocardium, and endocardium
What allows for spontaneous contraction of the heart
Autorhythmic cells, Cell to cell transmission, and Antitetanic
What are the two key cell types in the heart
Autorhythmic and Contractile
RMP of autorhythmic cells
-60
Describe RMP of autorhythmic cells
Net Na+ influx is greater than net K+ efflux.
True or false: Cardiac and skeletal muscle require extracellular Ca2+ to contract
False. Only cardiac muscle needs extracellular Ca2+
what does extracellular Ca2+ do for cardiac muscle
Induces SR release of Ca2+
Chronotropic
Time of contraction
Ionotropic
Force of contraction
Dromotropic
AV conduction
Lusitropic
Relaxation
Where is the hearts conduction system located
The heart walls
Atrial cells are innervated by
direct cell to cell contact
Myocardial cells are innervated by
the Purkinje system
The pacemaker of the heart is
The SA node
Where is the SA node located
The right atrium
List the internodal pathways
Anterior, Middle, Posterior-Posterolateral
Main function of the AV node
Delay conduction from the atria to the ventricles to allow for the atria to empty
The AV node is supplied by the
right coronary artery
The only route of communication between the atria and ventricles is called
The bundle of His
What supplies the Bundle of His
Left anterior descending and Posterior descending artery
What’s the first bundle branch to depolarize
Left bundle branch
How many fascicles does the left bundle branch have
3
Left anterior fascicle is ___ stranded and innervates the ___
ingle, anterior/superior aspects of LV
Left posterior fascicle is a _____ like structure that innervates
Fan, posterior/Inferior aspects of LV
Why is the left posterior fascicle hard to block
It is widely distributed
Left mid septal fascicle is found in ___ percent of humans innervates the ___
85, Mid septal area
Where does the left mid septal fascicle rise from?
The LBB generally but may rise from another fascicle
The right bundle branch innervates the
RV and interventricular septum
Where are the Purkinje cells located
Endocardium
What do Purkinje cells innervate
Myocardial cells
SA node inherent pace is
60-100
Atrial cells inherent pace is
60-80
The Junction’s inherent pace is
40-60
The ventricles inherent pace is
20-40
A vector represents
The sum total of energy and its direction
The final vector
is the electrical axis of the heart
An upwards wave results from
An impulse moving toward an electrode
Inferior leads
II, III, aVF
Lateral leads
I, aVL, V6, V5
Septal leads
V1, V2
Anterior leads
V3, V4
What direction does aVR look in
Fuck you thats what direction
Where is V1 placed
4th intercostal space, R sternal border
Where is V2 placed
4th intercostal space, L sternal border
Where is V3 placed
Midway between V2 and V4
Where is V4 placed
5th intercostal mid-clavicular line
Where is V5 placed
Anterior axillary line
Where is V6 placed
Mid axillary line
What is the rhyme to remember limb lead placement in adults
Red heart on the left, smoke over fire. Clouds over fields.
All limb leads should be how far from the heart?
10 cm
EKG height is measured in
millimeters
EKG width is measured in
Milliseconds
A small box on an ekg is
0.04 seconds
A big box on an EKG is worth
0.2 seconds
A Q wave is significant if
0.03 seconds or wider, height equal to or greater than 1/3 height of the R wave, Indication of MI
The ST segment begins at
the J point
A normal QT interval lasts
less than 1/2 the R-R
