Vascular Exam 1 - Hemodynamics and Cerebrovascular (Notes)

We typically differentiate types of vessels based on their _____ of the vasular system, meaning are they venous or arterial, and their _____.

side, size

Larger, flow away from heart; oxygen rich

Arteries

• Smaller arteries, they slow down flow velocity; increased resistance to flow due to their decreased radius

• Are called resistance vessels because they can contract or dilate to control flow and peripheral resistance

Arterioles

Arterioles have increased _____ to flow due to their decreased radius.

resistance

• Smallest vessels

• Nutrient exchange (delivery), gas exchange, waste removal, vessel “hand shake”

• Connect the arterial side to the venous side

Capillaries

Smaller veins, collect blood from capillary bed and send it to the veins

Venules

• Larger, flow towards the heart (right atrium); high capacitance/storage for blood

• Most of the blood of the circulatory system is housed in these (approximately 70%)

Veins

• Innermost vessel wall layer; the layer that actually touches blood

• Made of endothelial cells supported by elastic lamina

• Functions:

  • Permeability

  • Antithrombogenic

  • Vasoreactivity

• *Valves in veins; this layer forms valves

Tunica intima

What layer of the vessel wall forms valves?

Tunica intima

• Projections into the vessel lumen

• Ensure one-way flow back up to the heart

• Only found in veins

Valves

• Middle muscular vessel wall layer

• Made of smooth muscle cells and collagen

• Thicker in arteries than in veins; this is the thickest layer in arteries

• Functions:

  • Vasoconstriction and dilation (arteries)

Tunica media

What is the thickest layer in arteries that allows for vasoconstriction?

Tunica media

Arteries _____ or _____ in response to the cardiac cycle (exercise = _____, cold weather = _____)

contract, dilate, dilate, contract

• Outer vessel wall layer

• Made of connective tissue, collagen, vasa vasorum

  • This layer contains the vasa vasorum, which supplies blood to the vessel wall itself

• So this layer is sometimes referred to as “the blood vessel of the blood vessel”

Tunica adventitia

This, located in the tunica adventitia, supplies blood to the vessel wall itself

Vasa vasorum

Where does the aorta start?

LVOT

The aorta starts at the _____ where it exits the _____ _____. It becomes the _____ aorta then the _____ _____ giving rise to three branches: the _____ (_____) artery, the _____ _____ _____ artery, and the _____ _____ artery. Then it becomes the _____ _____ aorta. Once the aorta passes below the _____, it is classified as the _____ aorta. The _____ aorta has several branches, the first being the _____ _____, then the _____, the _____ arteries, the _____, and then it bifurcates into the _____ arteries.

LVOT, left ventricle, ascending, aortic arch, brachiocephalic, innominate, left common carotid, left subclavian, descending thoracic, diaphragm, abdominal, abdominal, celiac axis, SMA, renal, IMA, iliac

Technically, the first branches of the aorta are the _____ _____ at the aortic _____.

coronary arteries, root

The brachiocephalic artery branches into the _____ _____ _____ artery and the _____ _____ artery

right common carotid, right subclavian

The left/right common carotid artery bifurcates into the left/right _____ and _____ carotid arteries, which then terminate in the _____ _____ _____ at the base of the brain.

internal, external, Circle of Willis

The right vertebral artery branches from the _____ _____ _____

right subclavian artery

The left subclavian artery gives rise to the _____ _____ _____

left vertebral artery

Anatomy – Upper Extremity Arteries

• The right subclavian artery is a continuation of the _____ _____ after the _____ _____ _____ artery branches off of it

• Once the subclavian artery passes below the _____, it becomes the _____ artery

• The _____ artery continues to the bicep area and becomes the _____ artery

• At the level of the elbow or the _____ fossa, the _____ artery bifurcates into the _____ and _____ arteries

  • _____ = thumb side

  • _____ = pinky side

brachiocephalic artery, right common carotid, clavicle, axillary, axillary, brachial, antecubital, brachial, radial, ulnar, Radius, Ulna

Anatomy – Lower Extremity Arteries

• The common iliac arteries bifurcate into the _____ and _____ iliac arteries

• The _____ iliac artery is also called the _____ artery

• The _____ iliac artery becomes the _____ _____ artery once it passes below the _____ _____

• The _____ _____ artery bifurcates into the _____ (_____) and the _____ (_____) arteries

• The _____ _____ artery continues down the medial thigh until it passes behind the leg to the _____ or the _____ fossa. Here it gives rise to the _____, which consists of the _____ _____ artery (ATA), _____ artery, and _____ _____ artery (PTA).

• The ATA, peroneal, and PTA continue down the leg to the _____. The PTA and peroneal are more _____ and the ATA is more _____.

• The ATA eventually comes down on top of the ankle and becomes the _____ _____ (DP) artery

internal, external, internal, hypogastric, external, common femoral, inguinal ligament, common femoral, deep, profunda, superficial, femoral, superficial femoral, knee, popliteal, trifurcation, anterior tibial, peroneal, posterior tibial, foot, medial, lateral, dorsalis pedis

Veins (IVC and SVC) terminate at the…?

right atrium (RA)

When scanning arteries and veins in lab, we will always use the terms proximal, mid, or distal to describe what part of the vessel we are looking at. _____ is closest to the heart and _____ is furthest from the heart.

Proximal, distal

Anatomy – IVC

• The IVC terminates at the _____ _____ of the heart

• The IVC is formed by the confluence of the _____ _____ veins, which continue superiorly, accepting additional _____ until the IVC gets to the heart

• The _____ veins are the first tributary in relation to the heart (most _____) followed by the _____ veins

• The left gonadal vein empties into the _____ _____ vein

• The right gonadal vein empties directly into the _____

• The common iliac veins are formed by the confluence of the _____ and _____ iliac veins

right atrium, common iliac, tributaries, hepatic, proximal, renal, left renal, IVC, internal, external

Anatomy – SVC/Upper Extremity

• Opposite the IVC in the right atrium is the _____ _____ _____ (_____)

• The SVC is the final destination for all _____ extremity and _____ venous blood before dumping into the _____ _____

• The SVC is formed by the confluence of the _____ (_____) veins

• The _____ veins are formed by the confluence of the _____ and _____ _____ veins

• In the venous system, there is a _____ and _____ brachiocephalic (innominate) vein while in the arterial system, there is only a _____ brachiocephalic (innominate) vein

• The subclavian vein is formed by the confluence of the _____ vein and the _____ vein (a _____ vein)

• The _____ vein is at the bicep. The brachial vein is the confluence of the _____ and _____ veins.

• The _____ vein is another _____ vein that confluences with the brachial vein to form the _____ vein

• _____ veins of the arms and legs are paired with an artery

  • A lot of times, there are _____ veins to _____ artery

superior vena cava, SVC, upper, cerebrovascular, right atrium, brachiocephalic, innominate, brachiocephalic, subclavian, internal jugular, right, left, right, axillary, cephalic, superficial, brachial, radial, ulnar, basilic, superficial, axillary, Deep, two, one

Anatomy – Lower Extremity Veins

• The common iliac vein is formed by the confluence of the _____ and _____ iliac veins

• The external iliac vein is formed by the confluence of the _____ and _____ _____ veins

  • The external iliac vein becomes the common iliac vein once it passes under the _____ _____, just like on the arterial side

• The _____ _____ vein is the confluence of the deep (profunda) femoral vein and the superficial femoral vein

• The superficial femoral vein is located down the _____ aspect of the thigh

• The _____ vein is located at the level of the knee

• There is a confluence of veins at the _____ fossa of the _____ _____ vein (ATV) and the _____ _____ _____

  • The tibial peroneal trunk consists of the _____ _____ vein, the _____ _____ vein, and the _____ vein

internal, external, deep, superficial femoral, inguinal ligament, common femoral, medial, popliteal, popliteal, anterior tibial, tibial peroneal trunk, anterior tibial, posterior tibial, peroneal

The highest pressure in the vascular system is in the…? (100-140 mmHg)

Left ventricle / ascending aorta

Rapid rise in pressure of the left ventricle

Cardiac contraction

Once the left ventricle pressure exceeds the _____ pressure, the _____ _____ (_____) opens and blood is pumped out to the body

aorta, aortic valve, AoV

The pressure wave that travels rapidly throughout the vascular system decreases in pressure as it travels _____.

distally

Cardiac output (CO) =

stroke volume (SV) x heart rate (HR)

Amount of blood ejected in one beat

Stroke volume

How fast the heart is beating

Heart rate

Although the left ventricle generates the force, the _____ _____ between the venous and arterial sides of circulation creates movement!

pressure difference

The lowest pressure in the body is found in the…? (3 to 8 mmHg)

right atrium (RA)

Blood tends to flow from areas of _____ pressure to areas of _____ pressure

high, low

The movement of any fluid requires a _____ and a _____/_____ _____.

pathway, pressure/energy difference

The amount of flow depends on the _____/_____ _____ and _____ (peripheral).

pressure/energy difference, resistance

There is a significant drop in _____ at the arteriole/capillary level due to increased _____.

Why? Because there needs to be a decreased _____ and slowing of fluid at the level of the capillaries in order for nutrient exchange to happen effectively. Also, capillaries have very thin walls and would not be able to sustain high _____ or high _____.

pressure, resistance, pressure, pressure, velocity

• Blood will move from one point to another in response to differences in “_____” energy

  • Total energy = _____ energy + _____ energy

  • _____ = stored or resting energy

  • _____ = work or energy of motion

total, potential, kinetic, potential, kinetic

_____ energy in the vascular system is primarily represented by intravascular pressure, which distends vessels. This pressure is supplied by the contraction of the heart.

Potential

_____ energy in the vascular system is presented by the velocity of moving blood.

Kinetic

Realistically there is always some energy “loss” in the vascular system as a result of _____ and _____.

viscosity, inertia

Resistance to flow, blood thickness; increases with increased hematocrit (concentration of RBCs)

Viscosity

Law of motion; occurs when blood is forced to change direction or velocity

Inertia

The slower the rate of flow, the higher the pressure, and the faster the rate of flow, the lower the pressure.

P = 4v²

Q = V x A

Bernoulli’s Principle

Velocity and pressure in the vascular system (Bernoulli) are _____ related.

inversely

We describe the type of _____ in a vessel based on how the layers of blood are traveling relative to each other.

flow

A type of flow where all of the layers flow in parallel lines.

• Has two types:

  • Parabolic

  • Steady/Plug

Laminar

Type of laminar flow; layers along the vessel wall are slower due to friction, middle layers are faster

Parabolic

Type of laminar flow; all layers moving at the same velocity

Steady/Plug

Non-laminar flow; chaotic

• _____ = areas of swirling flow (helical flow)

Turbulent, Eddies

Velocity variations with the cardiac cycle, which cause the vessel diameter to expand or contract affecting flow direction; this type of flow reflects flow above and below the pulse wave baseline

• Typical of arterial flow

Pulsatile

Velocity variations with respiration

• Typical of venous flow

Phasic

What causes the difference between plug and parabolic flow?

Friction

The smaller the vessel, the _____ the friction

GREATER

• Turbulent flow occurs when _____ _____ is exceeded

  • _____ _____ is an abstract, dimensionless number that is used to determine when flow will become turbulent

  • _____ or greater = flow is turbulent

Reynold’s number, Reynold’s number, 2000

Turbulent flow is often seen _____ to a significant stenosis or at a vessel _____

distal, bifurcation

• _____ _____ (_____): How much blood is moving

  • Milliliters per minute OR liters per minute

• _____ (_____): How fast the blood is moving (speed); rate of change in position over time

  • Centimeters or meters per second

• _____ (_____): Cross sectional dimension of a vessel

  • mm or cm squared

Flow Volume, Q, Velocity, V, Area, A

Defines the relationship between flow, pressure gradient, vessel radius, vessel length, viscosity

Poiseuille’s Law

According to Poiseuille’s Law, the change in pressure and vessel radius are _____ related to flow.

directly

According to Poiseuille’s Law, the viscosity and vessel length are _____ related to flow.

inversely

What factor has the GREATEST effect on flow?

Vessel radius

Poiseuille’s Law:

Q = ΔPπr⁴ / 8Lη

• Vasoconstriction – vessel contracts

  • Radius _____

  • _____ resistance to flow

• Vasodilation – vessels relax or dilate

  • Radius _____

  • _____ resistance to flow

decreases, MORE, increases, LESS

Resistance Equation:

R = 8Lη / πr⁴

Resistance and flow are _____ related.

inversely

The highest point of a pulse wave tracing (flow profile)

Peak systolic velocity (PSV)

Where the pulse wave tracing (flow profile) stops before a new waveform begins

End diastolic velocity (EDV)

• The time it takes to get to peak systole from one waveform to the next

• You would measure from the diastole of the first waveform to the peak systole of the next waveform

Acceleration (AC) time

A calculated measurement that assesses blood flow resistance within an artery

• It essentially means more or less variation between peak systole and end diastole

Resistive Index (RI)

• A higher resistance waveform is going to have a _____ resistive index (RI)

• A lower resistance waveform is going to have a _____ resistive index (RI)

higher, lower

Resistive Index (RI) formula:

RI = (PSV - EDV) / PSV

• We can tell if flow is turbulent or laminar based on the _____ _____

  • The more open (black) the spectral window, the _____ turbulent the flow

  • The more filled in the spectral window, the _____ turbulent the flow

• We can tell how much blood we are sampling (how much blood is going through our pulse wave sample gate) based on how _____ the white part of the tracing is (spectral width)

  • A thicker tracing = a _____ gate

  • A thinner tracing = a _____ gate

spectral window, less, more, thick, wider, smaller

Does the image show pulsatile or phasic flow?

Pulsatile (Variable velocity and direction based on the cardiac cycle)

Does the image show pulsatile or phasic flow?

Phasic (Continuous/steady flow that is dependent on respiratory variations)

A surgical procedure to remove fatty plaque buildup from the inside of a blocked or narrowed artery

Endarterectomy

The CCA has a _____ resistance when it’s closer (proximal) to the heart, BUT we will characterize it as a _____ resistance vessel.

higher, low

High or low resistance?

• ICA =

• Vertebral Arteries =

• ECA =

low, low, high

The _____ of the CCA is where the CCA is slightly bigger before it bifurcates into the _____ and _____

bulb, ICA, ECA

True or false: You should pulse wave the bulb of the CCA

False (unless pathology is visualized in the bulb)

Differentiating ICA/ECA

• The ICA is usually _____, _____ resistance, usually always has color fill since it feeds the _____ (constantly _____), and is usually more _____

• The ECA is usually _____, _____ resistance, typically has a _____ moment where it doesn’t fill with color (PULSES/FLASHES) because it doesn’t have constant _____, and is typically more _____

  • The ECA has _____ branches (outside the brain)

  • The ICA branches once it is inside the _____, so we wouldn’t see those

• ***Vascular anatomy is notorious for not being like the textbook, meaning the ICA and ECA can switch on which one is more medial and which one is more lateral

larger, low, brain, perfusing, lateral, smaller, high, small, perfusion, medial, extracranial, brain

Carotid Interpretation % Stenosis Grading Chart

Normal values with NO stenosis (ICA PSV, Plaque Estimate, ICA/CCA Ratio, ICA EDV)

<180 cm/s, None, <2.0, <40 cm/s

Carotid Interpretation % Stenosis Grading Chart

Values with <50% stenosis (ICA PSV, Plaque Estimate, ICA/CCA Ratio, ICA EDV)

<180 cm/s, <50%, <2.0, <40 cm/s

Carotid Interpretation % Stenosis Grading Chart

Values with 50-69% stenosis (ICA PSV, Plaque Estimate, ICA/CCA Ratio, ICA EDV)

180-230 cm/s, >50%, 2.0-4.0, <100 cm/s

Carotid Interpretation % Stenosis Grading Chart

Values with ≥ 70% stenosis but < near occlusion (ICA PSV, Plaque Estimate, ICA/CCA Ratio, ICA EDV)

>230 cm/s, >50%, >4.0, >100 cm/s

Carotid Interpretation % Stenosis Grading Chart

Values with near occlusion (ICA PSV, Plaque Estimate, ICA/CCA Ratio, ICA EDV)

High/low/undetectable, visible, variable, variable

Carotid Interpretation % Stenosis Grading Chart

Values with total occlusion (ICA PSV, Plaque Estimate, ICA/CCA Ratio, ICA EDV)

Undetectable, no visible lumen, N/A, N/A

Use a _____ than _____ box for color!

taller, wide

Where is the Circle of Willis located?

The base of the brain

What are the first branches of the aorta?

Coronary arteries

What are the two branches of the brachiocephalic (innominate) artery?

Right common carotid artery, right subclavian artery

The vertebral arteries are a branch off of the _____ arteries on both the right and left side!

subclavian

Common carotid arteries (CCA) become the _____ and _____ carotid arteries

• ICA – primary blood supply to the _____

  • _____% of CCA blood

  • Typically _____ vessel (width)

  • NO _____ branches!

  • The first branch of the ICA is the _____ artery

  • Typically located _____

  • _____ resistance

• ECA –  primary blood supply to the _____, _____, and _____

  • _____ extracranial branches

  • Typically _____ vessel (width)

  • The first branch of the ECA is the _____ _____ artery

  • Typically located _____

  • _____ resistance

internal, external, brain, 80, bigger, extracranial, ophthalmic, laterally, Low, face, neck, scalp, 8, smaller, superior thyroid, medially, High

The ophthalmic artery supplies the _____ artery of the _____

• The ophthalmic artery branches into the _____, _____, and _____ arteries

retinal, eye, Supraorbital, Frontal, Nasal

The ICA is divided into 3 segments:

1. _____ segment – extends from CCA bifurcation to the carotid canal of the petrous portion of the temporal bone

2. _____ segment – Courses through the petrous portion of the temporal bone and is inaccessible to ultrasound (US)

3. _____ (_____ _____) segment – consists of three areas: parasellar, genu (bend), supraclinoid

Cervical, Petrous, Cavernous, carotid siphon

Label the following ICA segments (1 → 7):

Cervical, Petrous, Cavernous, Parasellar, Genu, Supraclinoid, Ophthalmic artery