Arterial (Quiz 1) Flashcards
Label a waveform
…..
What does the end diastolic flow demonstrate?
It shows the direction blood is moving - where it is going
What does the spectral window demonstrate?
If it is clean, it is laminar flow
If not, it’s turbulent flow
What happens to the upstroke if there is a blockage between the heart and sample position?
it becomes longer
What is fluid energy?
blood always moves from an area of high energy to an area of lower energy.
Name the types of pressure.
dynamic, hydrostatic, and static
Describe each type of pressure.
dynamic: changing pressure due to heart pumping
hydrostatic: created by weight of gravity on fluid column
static: exists throughout the body based on fluid balance of what’s in the vessel and soft tissue
What is Bernoulli’s Principle?
when a fluid flows without a change in velocity from one point to another, the total energy content remains constant, providing no frictional losses
if velocity remains constant from one point to another, so does the energy
What does Bernoulli’s Principle demonstrate?
velocity and pressure are inversely related.
Where does turbulent flow happen?
When narrowing, blocking or a vessel branches
What is viscosity?
the friction that exists between bordering layers of fluid
How is viscosity related to velocity?
inversely related
What is a hydraulic filter?
converts the pulsatile output of the heart to a steady flow through the capillaries
(triphasic waveform comes from hydraulic filter property)
How is energy lost?
through friction and inertia
What is friction?
energy lost in form of heat
How is energy lost through inertia?
when a vessel branches or bifurcates, energy will be lost at branch points
(more severe branching angle, the more turbulent flow)
What are the relationship properties with velocity and flow?
V = Q/A
velocity is directly related to flow
velocoty is inversely related to area
(flow is constant because of closed system)
As the total cross-sectional area increases throughout the body, what happens to blood velocity?
decreases
the farther distal, the lower the velocity will be because of the greater cross-sectional area and energery loss (over time)
What does Poiseuille’s Law demonstrate?
radius and pressure change is directly related to flow
viscosity is inversely related to flow
Describe the resistance equation
resistance is equal to the pressure drop divided by flow
resistance is inversely related to radius/diameter
blood vessel length is virtually constant as is blood viscosity
What is vascular impedance?
resistance offered by a peripheral vascular bed to pulsatile flow
Describe low resistance patterns.
dilated distal arteriolar bed, antegrade flow, typical of vessels that supply organs
Describe high resistance patterns.
slight vasoconstriction, antegrade and retrograde flow, typically found in vessels that perfuse muscles
Regulation of blood flow into the distal tissue beds is regulated primarily by what?
arterioles
What causes vasodilation in a high resistance vessel?
exercise
decreases resistance
same occurs in SMA
What is a stenosis?
an abnormal or pathologic narrowing in a blood vessel or other tubular structure
What causes most of the energy loss in a vessel?
changes in vessel radius
small change in radius results in large changes in resistance/viscous energy losses
inertial energy loss occurs at the entrace and exit of a stenosis
What is a critical stenosis?
degree of narrowing at which pressure and flow begin to be affected
typically occurs when cross-sectional area has been reduced by 75%
What is a tandem lesion?
more than one plaque in a row (blood hasn’t exited one stenosis when another stenosis occurs)
Where do athersclerotic changes typically occur?
at branch points and bifurcations
What is a collateral?
when blood flow is totally occluded, blood will find another way (rerouted)
collateral flow is a sign of blockage
Describe the normal electrical pathway of the heart.
SA node - interatrial pathways - atria - internodal pathways - AV junction(AV node to bundle of HIS) - left bundle branch - right bundle branch - purkinje fibers
Label the waves of one heart beat.
….
What does the P wave represent?
atrial depolarization
What does the QRS complex represent?
ventricular depolarization
What does the T wave represent?
ventricular repolarization or the recovery phase
What is considered a normal heart rhythm?
cardiac cycles of equal length(regular), similiar waveforms, equal number of p waves and QRS complexes
What are the four classifications of arrhythmias?
sinus, atrial, junctional, and ventricular
What is a sinus arrhythmia?
disturbances arising in the SA node
the heart can speed up or slow down
What is an atrial arrhythmia?
disturbances arising in the aorta
What is a junctional arrhythmia?
disturbances arising in the AV node
What is ventricular arrhythmia?
disturbances arising in the ventricles
ventricular contraction is effected
What is classified as a minor arrhythmia?
not of immediate concern; do not affect circulation; do not warn of development of more serious rhythm disturbances
What is classified as a major arrhythmia?
reduce the pumping efficiency of the heart; warn of the onset of lethal arrhythmias; require prompt attention/treatment
What is classified as death producing arrythmias?
lethal; requires immediate resuscitation
example: ventricular fibrillation (absent Pwave)
Describe an atrioventricular block.
a suprarentricular impulse is unable to be conducted normally through to the ventricles because of a condition disturbance at or below the AV node
abnormality in electrical conduction between the atria and ventricles
List (from less to most) the severity types of AV blocks.
1st degree; 2nd degree type 1 (wenckebach); 2nd degree type 2 (mobitz); 3rd degree (complete block)
Define tachycardia.
greater than 100 BPM
it has a diminished peak systolic velocity and an elevated diastolic velocity
Define bradycardia.
less than 60 BPM
exaggerated peak systolic velocity
diminished diastolic velocity
may mimic high resistance pattern
What are signs of aortic stenosis?
higher velocity, less volume
if distal to stenosis: decreased velocity and delayed acceleration time
If there is an aortic stenosis, how can you be sure it’s not in the artery you are scanning, for example, a carotid study?
Take a look at the other carotid artery and if the same wave form is seen, it is aortic stenosis and not in just the one vessel
aortic stenosis will cause the same waveform throughout the body
What is aortic regurgitation?
when the aortic valve is letting blood back into the heart (like a swinging door)
blood is not maintaining a constant velocity
What is CHF?
blood leaving the heart that isn’t reaching the need to supply the body tissues
List each layer of arteries and what they are composed of.
tunica intima (innermost): endothelial lining with connective tissue components beneath it tunica media (middle): smooth muscle tunica adventitia (outermost): connective tissue, nerve fibers, small vessel capillaries
What is the thickest of the three artierial layes?
tunica media
Which arteries supply most of the blood to the brain and eyes?
the right and left internal carotid arteries
Which carotid artery does not contain any extracrainial branches?
the ICA
How many branches arise off the ECA?
eight
superior thyroid, lingual, facial, occipital, posterior auricular, ascending pharyngeal, maxillary, superficial temporal arteries
Does the ECA supply blood to the brain?
no
serves as important collateral pathway
What are the four arteries that supply blood to the brain?
right and left vertebral arteries and right and left ICA’s
What is the largest branch of the brachial artery?
deep brachial artery
Which artery is larger, the ulnar or radial?
ulnar
When does the abdominal aorta begin?
at the level of the 12th thoracic vertebra
When does the aorta terminate?
level of the fourth lumbar vertebra
Which vessels carry oxygenated blood to the liver?
hepatic artery and portal vein
Where is the highest pressure within the vascular system?
the left ventricle
Where is the lowest pressure within the vascular system found?
the right atrium
What happens to blood velocity as it travels from the aorta through the arteries, arterioles and finally through the capillaries?
What happens to the blood velocity as it travels back to the heart?
it decreases
it increases
A low resistance flow profile characteristically has what type of flow throughout the cardiac cycle?
antegrade
What does high resistance flow demonstrate?
both antegrade and retrograde
Stated by Poiseuille’s Law, if the viscosity of blood increases, what will happen to the flow?
it will decrease
According to what principle will the radius of a vessel have a significant impact to blood flow?
Poiseuille’s Law
According to what principle will the vessel radius have a significant impact on resistance?
Ohm’s Law
What is the Reynolds number directly proportional to?
velocity of blood, density of blood, and radius of blood vessel
What is the Reynolds number inversely proportional to?
blood viscosity
What will the Reynolds number be for laminar flow? Turbulent flow?
below 2,000
above 2,000
What are resistance vessels? What is another name for them?
vessels involved in regulating blood flow
arterioles
What will effect the vasomotor tone?
oxygen, carbon dioxide, hydrogen ions, potassium ions
What do resistance vessels do in response to high and low blood pressure?
high: dilate
low: constrict
Where does atherosclerosis typically develop?
at branch points and bifurcations
Most abnormal energy losses in the arterial system result from what?
stenoses or obstruction of the vessel lumen
When viewing a stenosis, is the length or radius most important?
radius
Where is initial energy loss encountered?
at entrance and exit of a stenosis
more so at the exit
Define a critical stenosis.
a degree of narrowing at which pressure and flow begin to be affected.
What are the divisions of collateral arteries?
stem arteries (large branches) midzone collaterals (small intramuscular branches) reentry arteries (vessels that rejoin a major artery distal to area of stenosis/occlusion)
What is the typical pressure in mmHg’s exerted by static pressure?
5-10 mmHg
What does the static pressure depend on?
volume of blood and elasticity of vessel walls
What does hydrostatic pressure depend on?
specific gravity of blood and height above or below right atrium
What does Poiseuille’s Law describe?
the steady laminar flow of Newtonian fluids and the pressure/flow relationships in the vascular system
Pressure and flow vary with ____.
time
