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Vascular I
Terms and facts for Vascular Ultrasound.
173
Anatomy
Professional
05/22/2012
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Term
Cerebrovascular Accident
 Definition
CVA. Aka;stroke. Permanent or semi-perminent impairment.
Term
Transient Ishemic Attack
 Definition
TIA. Symptoms resolve within 24hrs.
Term
Hemiparesis
 Definition
Weakness in one side of the body, face, arm, leg. Contralateral hemisphere.
Term
Hemiplegia
 Definition
Total paralysis of one half of the body, face, arm, leg. Contralateral hemisphere.
Term
Lateralized Paresthesia
 Definition
Numbness and tingling of extremities.
Contralateral (opposite) hemisphere.
Term
Aphasia
 Definition
Inability to speak or express oneself.
Dominant hemisphere, usually left.
Term
Dysphasia
 Definition
Impairment of speech, lack of coordination and failure to arrange words in proper order. Dominant hemisphere.
Term
Dysarthia
 Definition
Imperfect articulation of speech due to disturbances of muscle control,slurring, dysfunction of any number of brain centers.
Term
CVA/TIA Symptoms
 Definition
Hemiparesis,hemiplegia, generalized weakness/motor dysfunction, parethesis & ipsilateral visual disturbances (amaurosis fugax).
Term
Amaurosis Fugax (AF)
 Definition
Aka: Transient Monocular Blindness(TMB). Ipsilateral (same side) artery.
Term
Ataxia
 Definition
Gross incoordination of muscle movements, clumsiness of limb. Contralateral hemisphere.
Term
Carotid Disturbance Symptoms
 Definition
Speech difficulty-usually left hemisphere,aphasia,dysphasia, dysarthria,sudden confusion,trouble understanding speech,sudden severe headache w/no cause & death.
Term
Vertebral-Basilar Symptoms
 Definition
Drop attack,blackouts,syncope,memory loss,vertigo,dizziness,diplopia(double vision),binocular blindness, headaches, neck pain & death.
Term
CVA Causes
 Definition
Cardiac:Emboli(free floating), cessation of perfusion.
Carotid Etiology: About 50%, thrombosis (stenosis=artery,clot=vein.
Aneurysm Rupture: Intracranial hemorrhage, vasospasm.
Term
Infarct vs Ischemic
 Definition
Complete lack of blood flow.
Narrowing getting reduced blood flow, enough until exertion.
Term
Cerebrovascular Risk Factors
 Definition
Family history of Peripheral Artery Disease (PAD), Smoking, Old age, Diabetes mellitus, Hypertension, High Cholesterol.
Term
First Branch of the Aorta
 Definition
Coronary Arteries.
Term
First Branch of the ECA
 Definition
Superior Thyroid A.
Term
First Branch of the ICA
 Definition
Ophthalmic A.
Term
Circle of Willis
 Definition
Only 50% have an intact and working circle.
Only 25% have the classic configuration.
Term
Carotid Protocol
 Definition
1.Patient History 2.Transverse Images
3.Longitudinal Images 4.Color Doppler 5.Spectral Doppler 6.Mapping areas of flow disturbance (pre-within-post)
Term
Collateral
 Definition
Alternate pathway for blood flow.
Term
ICA Waveform
 Definition
Low resistance.
Term
ECA Waveform
 Definition
High resistance.
Term
Vertebral Flow
 Definition
Should be going in the same direction as carotids. Antegrade.
Term
% Stenosis via NASCET Method
 Definition
% Stenosis = 100*(1-Residual Lumen/True Lumen).
Term
Vertebral Waveform
 Definition
Usually more low resistant.
Term
Carotid Criteria Caveat #1
 Definition
Must have all Three:
1.Focal Velocity acceleration
2.Plaque
3.Post Stenotic Turbulence
Criteria is only for grading stenosis not determining normal.
Term
PSV
 Definition
Peak Systolic Velocity.
Term
EDV
 Definition
Peak End-Diastolic Velocity.
Term
50% Stenosis
 Definition
Significant velocity acceleration occurs at stenosis of 50% diameter or greater. Velocities do not appreciably increase over stenosis less than 50%.
Term
Criteria Objective Parameters
 Definition
1.Stenosis diameter measurement (optional) 2.PSV at amx stenosis 3.EDV at max stenosis 4.ICA/CCA ratio 5.Absence of flow
Term
ICA/CCA Ratio
 Definition
PSV at max stenosis/PSV from a disease free part of mid CCA.
Term
Tardus Parvus Waveform
 Definition
Loss of amplitude and delayed rise time.
Seen distal to a stenosis.
Suggests proximal stenosis.
Term
Carotid Stent
 Definition
Used to hold a vessel open, pushes plaque against the vessel wall. Sampl prox,mid,distal,more distal. Hyperechoic, can look like x's.
Term
Carotid Dissection Proximal
 Definition
In CCA, progression of Aortic dissection. False Lumen. Usually asymptomatic. ICA extension uncommon.
Term
Carotid Dissection Distal
 Definition
Mid to distal ICA. No false lumen. Subintimal hematoma. Flow restrictive. Symptomatic.
Term
Fibromuscular Dysplasia (FMD)
 Definition
A non-atherosclerotic, non-inflammatory
arterial disease. Idiopathic. Fibrous thickening of the intima,media or adventitia. 90% women, w/hypertension, usually bilateral, prox. and dist. ICA.
Seen as turbulence w/wo velocity increase.
Term
Carotid Body Tumor
 Definition
Aka; Chemodactoma. Highly vascular, often benign, often in "crotch" of bifurcation.
Term
Carotid Criteria Caveat #2
 Definition
Image is best with stenosis < 50%.

Spectral Doppler is best with stenois > 50%.
Term
Society of Radiologists in Ultrasound (SRU) Recommmendations
 Definition
1.Gray scale,color & spectral doppler.
2.Doppler at 60° or less.
3.ICA from bulb to distal
4.Final report should discuss B-mode image and color doppler & technical limitations.
5. Compare to any previous reports in report.
6.Estimate degree of ICA stenosis.
7, Angiograms use NASCET method for stenosis.
8.Quality Assurance and internal validation.
Term
Revised SRU Criteria Table
 Definition
% Sten. PVS Plaque Est. ICA/CCA EDV
Normal <125 none <2.0 <40
<50 <150 <50 <2.0
50-60 >150 >50 2-4 60-100
≥70230 >50 >4.0 >100
NearOcc Var Vis Var Var
TotalOcc Undet Vis,No Lumen n/a n/a
Term
ICA Trickle Flow
 Definition
Can be fixed. Use low PRF color scale and Power Doppler to find flow.
Term
ICA Occlusion
 Definition
Can't be fixed. Really look with low PRF color scales and Power Doppler.
Term
CCA Stenosis
 Definition
No established Criteria.
If PSV increased by a factor of 2 over stenosis then probably a >50% stenosis.
Term
CCA Occlusion
 Definition
Verify no flow. Check ICA & ECA. ICA is often supplied with retrograde ECA flow.
Term
ECA Stenosis
 Definition
No established Criteria.
Abrupt increase in velocity, w/post stenotic turbulence.
Term
Stent Problems
 Definition
1.Poor Deployment
2.Stent Shift
3.Distal Stenosis
Term
Stent Stenosis Criteria
 Definition
% Sten. PSV ICA/CCA
50-69% >225 >2.5
≥70% >350 >4.75
Term
Anechoic
 Definition
The property of being echo-free or without echoes.
Term
Echolucent
 Definition
The property of being echo-free or without echoes.
Term
Sonolucent
 Definition
Allowing the passage of ultrasonic waves without echoes. Anechoic.
Term
Isoechoic
 Definition
Areas with similar echogenicity. Makes it more difficult to see the desired tissue structure.
Term
Echogenicity
 Definition
Echogenic, the ability to create an ultrasond echo.
Term
Hyperechoic
 Definition
Producing echoes of higher amplitude than normal for the surrounding medium.
Term
Hypoechoic
 Definition
Producing echoes of lower amplitude than normal for the surrounding medium.
Term
Plaque Morphology
 Definition
Smooth, Irregular, homogeneous, heterogeneous.
Term
Ulceration
 Definition
Sharp, irregular borders. Higher risk of emboli. Ultrasound is not very good at determining plaque ulceration.
Term
Intraplaque Hemorrhage (IPH)
 Definition
Hypoechoic area with thin fibrous cap.
Ultrasound is not very good at determining intraplaque hemorrhage.
Term
Subclavian Artery Exam Indications
 Definition
1.Supraclavicular Bruit (strange vessel sounds)
2.Reduced arm BPs
3.Abnormal vert. spectra or retrograde flow.
4.Arm weakness
Term
High Resistive Vertebral Waveform
 Definition
Seen with distal stenosis in vertebral or basilar a.
Proximal to stenosis.
Term
Lt. Subclavian Steal
 Definition
More common on left. Flow from the rt, verts augments to supply flow to the lt arm. Usually no neurological symptoms.
Term
Subclavian Steal Syndrome
 Definition
Subclavian steal & severe carotid disease. Causes neurologic symptoms.
Term
Rt. Subclavian Steal
 Definition
If rt. vert has retrograde flow look carefully at innominate,CCA & rt subclavian.
Term
Vertebral-Subclavian Assessment
 Definition
20mmHG gradient between left and right brachial pressures suggests subclavian stenosis. Don't take BP in an arm w/a shunt or dialysis access graft.
Term
Early Systolic Deceleration
 Definition
"Bunny Ears". Seen in vertebrals with subclavian stenosis. Start of retrograde flow. Can turn into progressive early systolic decel, "to & fro" & retrograde flow (severe stenosis).
Term
Subclavian Artery Waveform
 Definition
Triphasic: above/below/above. All peripheral arteries should have this form. Biphasic is abnormal!
Term
Deep Venous System
 Definition
85% of limb blood volume. Have an adjacent artery. Paired in the calf.
Many "normal" variations.
Term
Venous Waveform
 Definition
Should be phasic, not continous.
Term
Superficial Venous System
 Definition
Includes GSV & SSV. No adjacent artery.
Term
Perforators
 Definition
Aka: Communicators. Coonects the superficial and deep systems. Flow from S to D. Dodd's Group,Boyd's PV & Cockett's Group.
Term
Peroneal & Soleal Veins
 Definition
Are only dialated when there is a clot.
Term
Calf Muscle Veins
 Definition
Gastrocs & Soleal veins.
Term
Saphenofemoral junction
 Definition
Confluence of superficial veins & GSV prior to joining the CFV through the terminal valve.
Term
Blood Flow to Extremities
 Definition
Governed by: CO. Contractility of the heart. Arterial wall compliance.
Intraluminal pressure. Peripheral resistance at the capillary bed.
Term
Capillary Bed
 Definition
Small arterioles leading into capillary beds are constricted in basal state. During exercise they vasodilate. Resistance down, flow up. Increased blood volume supports increased metabolic activity. More blood volume back to the heart.
Term
Blood Flow
 Definition
Blood flows from areas of high pressure to areas of low.
Term
Hydrostatic Pressure
 Definition
The pressue that results from the force of fluid from a column of fluid. p=ρgh. About 22mmHg/12".
Term
Approx. Distal Venous Pressures
 Definition
Lying: 0-10mmHg
Standing: 80mmHg (based on height)
Walking: 25mmHg
Term
Hydrostatic Pressure Affect on Lower Veins
 Definition
Distal transmural venous pressure up, venous distension up, venous pooling up, capillary perfusion down, venous return down, cardiac output down, Hypotension results.
Term
Cardiac Influence & Venous Flow
 Definition
This effect is most pronounced in the thoracic vessels, and is reduced in the lower extremities. If seen in the LE often means CHF.
Term
Respiratory Variation & Venous Flow
 Definition
During inspiration (inhale) diaphragm moves down increasing intra-abdominal pressure. IVC is compressed and outflow is reduced or stops. Flow resumes during exhalation.
Term
Lower Extremity Pumps
 Definition
Foot Pump: primes the calf pump.
Thigh Pump: ejects thigh blood volume.
Calf veno-motor pump: major ejection.
Term
Venous Valve Distribution
 Definition
IVC:0,CIV:0,EIV:0(IN MOST),FV:4,POP:2, PTVs:10,PVs:10,ATVs:10
Term
Calf Veno-motor Pump
 Definition
Helps venous return to the heart. Reduces the effect of hydrostatic pressure. Reduces venous pooling. Dependent on competent valves,muscle contraction & patency of outflow veins.
Term
Venous Insufficiency
 Definition
Aka: Venous Incompetence. Primary: congenital absence or defect of valves.
Secondary: Postphlebitic syndrome;valves damaged by venous thrombosis or chronic outflow obstruction.
Term
Venous Insufficiency Symptoms
 Definition
Recurrent swelling. Varicose/Spider Veins. Venous Claudication (pain in legs while walking). Stasis Dermatitis (brown "gator area"). Ulceration (usually in "gator area").
Term
DVT
 Definition
Deep Vein Thrombosis.
Term
Blood Clot
 Definition
Applies to a clot anywhere, even in a test tube.
Term
Thrombosis
 Definition
The formation of a blood clot in an artery or vein.
Term
Thrombus
 Definition
Actual clot within a vessel.
Term
Thromboembolism
 Definition
A thrombus that breaks free and travels.
Term
Phlebitis
 Definition
Inflammation of vein wall.
Term
Thrombophlebitis
 Definition
Thrombus formation associated with phlebitis.
Term
Superficial Thrombophlebitis
 Definition
Thrombosis in a superficial vein.
Term
Pulmonary Embolism (PE)
 Definition
A thrombus that travels to the heart, through the heart and into the lungs.
"Saddle" Embolus: In the Pulmonary Trunk at the bifurcation of Pulmonary Arteries.
Term
Virchow's Triad
 Definition
1.Circulatory Stasis
2.Hypercoagulable State
3.Endothelial Injury
Term
Risk Factors for DVT
 Definition
Post - operative state, previous DVT,
cancer, thrombophilia, trauma, pregnancy, high dose estrogen RX, “economy class syndrome”, Bed-rest > 4 days, lower limb paralysis.
Term
Symptoms of DVT
 Definition
Persistent leg pain with acute onset.
Persistent leg swelling.
Calf pain/tenderness.
If patients have above symptoms, 50% chance of DVT.
Term
Clinical Diagnosis of DVT
 Definition
Low Sensitivity:
Many DVTs are clinically asymptomatic.

Low Specificity:
Non-thrombotic disorders can cause the same clinical symptoms as DVT.
Ex.Cellulitis.
Term
Phlegmasia Cerulea Dolens
 Definition
Symptoms with high positive predictive value for DVT. Massive thigh and calf swelling. Limb cyanosis. Ilio-femoral outflow obstruction.
Term
Symptoms of Superficial Thrombophlebitis
 Definition
Erythemia (redness) / inflammation.
Local tenderness. Palpable cord or mass. Usually more painful than DVT.
Term
Venous Physical Exam
Definition
Swelling. Limb discoloration. Stasis dermatitis, ulceration. Varicose veins.
Palpable “cords” (STP).
Term
Venous Duplex Techniques
 Definition
In order of importance: Compressibility / coaptation of vein.
Visualization of thrombus.
Spectral Doppler.
Color Doppler.
Term
Spectral and Color Doppler Techniques
Definition
Longitudinal Evaluation:
Spontaneous flow, phasic with respiration, augments with distal limb compression, reflux ?
Term
Continuous Venous Flow
 Definition
Could be: Shallow breathers (patients with pulmonary embolus-PE). Patients who are lying supine. Patients who have their arms raised and hands behind their head. Spinal cord injured patients due to reduced abdominal muscle tone. Proximal DVT or extrinsic venous compression.
Term
Common Femoral Veins & Doppler
 Definition
Always do both veins (bilaterally), for comparison, to rule out Iliac obstruction.
Term
DVT Perspective
 Definition
Thrombus from popliteal to iliac veins is Life Threatening.
Calf vein DVT may cause PE but thrombus is too small to be fatal. Same for great saphenous thrombosis.
Term
DVT; Acute vs. Chronic
 Definition
Acute: Distended,somewhat hypo-echoic,
no collaterals,maybe free floating. Chronic: Contracted(smaller than artery),echogenic thrombus,presence of collaterals,recannalization.
Term
Calf Vein Caveat
 Definition
If you find calf, SSV, or gastroc vein thrombosis, look carefully for extension into the popliteal vein.
Term
Criteria for Venous Thrombosis
 Definition
Absence of vein compressibility.
Visualization of thrombus.
Vein distention.
Abnormal Doppler signals.
Reduced / absent augmentation.
Reduced / absent color filling.
Term
Differential Diagnoses: Leg Pain & Swelling
 Definition
Popliteal/Baker's/Synovial Cyst, Dissected Cyst, Popliteal Artery Aneurysm, Muscle Tear, Hematoma,
Lymphedema-"Ant Farm", Cellulitis, May Thurner Syndrome, Tumor, Swollen Lymph Node, Abscess, Arterio-venous fistulas.
Term
May Thurner Syndrome
 Definition
Compression syndrome. Compression/ thrombosis of left iliac vein by overlying right iliac artery.
Term
Venous vs. Arterial Symptoms
 Definition
VENOUS ARTERIAL
Acute onset Progressive
Limb swelling Limb coolness
Persistent pain Intermittent pain
Local tenderness Limb pallor
Palpable “cord” Gangrene
Chest pain/SOB Tissue necrosis
Cyanosis Rest Pain
Warm
Term
Comparison of Symptoms: DVT vs. Insufficiency
 Definition
DVT Insufficiency
Persistent Swelling Recurrent Swelling
Persistent Pain Heaviness/Discomfort
Local Tenderness Varicose Veins
Limb Warmth Stasis Dermatitis
Short of Breath Ulceration
Term
Venous Symptoms for Upper
Extremities
 Definition
Pain & swelling in arm. SOB, Chest pain, Pulmonary Embolus? Dilated superficial veins of arm & shoulder.
Local erythemia. Palpable cord.
Catheter infusion difficulty.
Pre-operative assessment for hemodialysis access placement.
Term
Upper DVT: Etiology
 Definition
Intimal injury: indwelling venous catheter, pacemaker wire, stents.
Stasis: compression. Radiation induced. Fibrosis. Venipuncture.
IV drug abuse.
Term
Deep Veins of the Upper Extremities
 Definition
SVC, Innominate, Subclavian, Axillary,
Brachial, Radial, Ulnar.
Term
Superficial Veins of the Upper Extremities
 Definition
Basilic
Cephalic
Median Cubital
Term
Central Veins
 Definition
External jugular, Anterior jugular, Jugular arch vein, Transverse scapular,
Inferior thyroid, Internal mammary.
Term
Normal Upper Venous Flow
 Definition
Respiratory Phasicity & Cardiac Pulsatility.
Term
Contralateral Assessment of the Upper Extremities
 Definition
Because subclavian waveform assessment is critical, it is important (& required by ICAVL) that a comparison be made with the contralateral subclavian vein.
Term
Forearm Veins
 Definition
Only Scan: Local palpable cord, suspicion of superficial thrombophlebitis, infusion difficulty with peripherally inserted central catheters (PICC lines), pre-op assessment for hemodialysis access placement(superficial veins only),
pre-op for vein harvest for arterial bypass (determine patency and size).
Term
Criteria for Venous Thrombosis Upper Extremities
 Definition
Visualization of thrombus, lack of vein coaptation, no flow in Color and Spectral Doppler, abnormal flow patterns and flow direction in central veins.
Term
Paget-Schroetter Syndrome
 Definition
Spontaneous thrombosis of subclavian - axillary vein, effort induced, atomical
factors, hypercoagulability.
Extensive collateral development.
Term
Superior Vena Cava Syndrome
 Definition
Occlusion or compression of SVC.
Increased venous pressure.
Edema of neck, face and arms, usually bilaterally.
Term
Normal Upper Extremity Venous Interpretation
 Definition
1.All veins central to the axillary vein demonstrate cardiac pulsatility, respiratory phasicity, & central flow direction.
2.Color Doppler demonstrates complete intraluminal venous filling.
3.No intraluminal thrombus seen.
4.Contralateral subclavian vein flows are symmetrical.
5.Veins below the axilla are easily compressed & demonstrate complete filling with color when augmented distally.
Term
Abnormal Upper Extremity Venous Interpretation
 Definition
1.Visualization of thrombus.
2.In the proximal veins, absence of spontaneous flow or absence of cardiac pulsatility.
3.Persistent retrograde flow in the IJV or EJV suggests obstruction in the Innominate vein.
4.Lack of compression of any vein below the axilla, confirmed by the absence of flow with Color or Spectral Doppler.
5.Absence of flow, or a filling defect in veins above the axilla.
Term
Aneurysm
 Definition
Dilatation and expansion of arterial wall. May contain thrombus, platelet aggregates, debris.
Term
Aneurysm Risk Factors
Definition
Tobacco abuse. Hereditary/family history. Advanced age. Male gender (men are 5 times more likely).
High cholesterol. Obesity.
Term
Symptoms of Aneurysm
 Definition
Most intact aortic aneurysms are asymptomatic. Palpable pulsatile mass in abdomen. Back pain. Abdominal pain.
Term
Abdominal Aorta Aneurysm Complications
 Definition
Rupture:Correlation between size and mortality rate. > 5cm Must be repaired.
Thrombosis. Embolization. Males over 60 yrs old–highest risk group.
Term
Aortic Dissection
 Definition
Intimal tear, blood in tunica media. Thoracic Aorta Dissection is an emergrncy!
Term
Aorta Waveform
 Definition
Triphasic below the renals. Not triphasic above the renals.
Term
Renovascular Hypertension Causes
 Definition
Atherosclerosis, usually in the proximal renal artery, is most common etiology. Fibromuscular dysplasia (FMD). Dissection or extension of aortic dissection. Renal artery stenosis must be ≥ 70% before it’s likely to cause hypertension.
Term
Renal Doppler Indications
 Definition
Uncontrolled hypertension, especially in younger patients.
Decreasing renal function.
Abdominal bruit.
Term
Renal Doppler Purpose
 Definition
Identify vascular etiology of hypertension.
Prevent renal failure due to permanent parenchymal changes.
Evaluate renal transplants for complications.
Term
Renal Doppler Patient Preparation
 Definition
Overnight fast,morning exam, patients should be well hydrated: some labs request that patients drink 16 oz of water 30 minutes before the exam.
No chewing gum or tobacco, & no smoking prior to exam.
Term
Kidneys
 Definition
Measure each kidney length & compare to the contralateral side.
A 2-centimeter difference is significant. Normal adult kidney length is 9-12 cm.
Term
Main Renal Arteries- Normal Characteristics
 Definition
High flow velocity (PSV 100 ± 20 cm/s.)
Low resistance (RI < 0.75)
High diastolic flow vel. (EDV 30 ± 5 cm/s)
Term
Renal/Aortic Peak Systolic Velocity Ratio (RAR)
 Definition
The highest velocity obtained in the renal artery divided by the peak velocity from the aorta.
Term
Renal Doppler: Criteria for > 60% Stenosis
 Definition
Renal-Aortic Ratio (RAR) ≥ 3.5.
Peak Systolic Velocity (PSV) > 180 cm/sec.
Post stenotic turbulence.
Low flow in distal renal artery.
Term
Renal Doppler: Renal A. Occlusion
 Definition
No flow in well visualized renal artery.
Low amplitude signal from parenchyma.
Small kidney size (< 9 cm ).
Term
Renal Parenchymal Disease
 Definition
High resistance flow in kidney and main renal artery. Velocity is reduced.
Term
Renal Doppler: Indirect Criteria for > 60% Main Renal Artery Stenosis
 Definition
Sample Segmentals: Loss of early systolic peak (ESP). Acceleration time > 0.07- 0.1 sec. Abnormally low ipsilateral RI (< 0.75). Reduced color flow in kidney. Tardus Parvus Waveform.
Flattened systolic upslope.
Term
Renal Fibromuscular Dysplasia (FMD)
 Definition
Non-atherosclerotic, non-inflammatory arterial disease of unknown origin.
Fibrous thickening of vessel wall.
Predominance in women (90%).
Associated with hypertension.
Occurs in mid to distal segments of renal arteries.
Can occur in carotid arteries.
If renal artery stenosis is detected distal to the origin in mid segment, FMD should be suspected.
Term
Renal Doppler & Transplants
 Definition
R/O kinks / twists in renal artery.
RI for rejection:
Normal 0.73 ± 0.04
Abnormal > 0.8 ± .07
RI not universally accepted.
Term
Resistivity Index (RI)
 Definition
PSV-EDV/PSV
Term
Energy Gradient
 Definition
The energy level difference between two points. Must be present for fluid to flow from one point to another in a closed system. Fluid energy gradient is reflected in a pressure gradient.
Term
Pressure Gradient
 Definition
Highest pressure in arterial system is in left ventricle & thoracic aorta during systole. The intra-arterial pressure in distal vascular bed is lower during systole, so blood flows towards the vascular beds.
Term
Triphasic/Multiphasic Waveform
 Definition
Normal peripheral arterial waveform.
In systole, intra-arterial pressure is high, flow moves forward.
In diastole intra-arterial pressure is decreased and pressure distally is high (due to peripheral resistance)& flow reverses.
Third component is thought to be due to the elasticity of the arterial wall (rebounding).
Term
Laminar Flow vs. Parabolic Flow
 Definition
Laminar: A fluid flows in parallel layers with no disruption between layers.
Parabolic: Describes velocity profile.
Term
Friction
 Definition
Resistance of movement of one layer of blood against another layer or a wall.
The diameter of a vessel determines the amount of friction: the smaller the radius, the greater the friction and less amount of flow.
Term
Plug Flow vs. Parabolic Flow
 Definition
Plug Flow occurs during acceleration.
Systole: Plug Flow, narrow spectrum.
Diastole: Parabolic Flow, wider spectrum.
Term
Non-Laminar Flow
 Definition
Helical Flow & Flow Separation.
Term
Viscosity(η)
 Definition
Property of fluid that resists flow.
A friction that exists between adjacent layers of fluid or a wall.
Higher viscosity, higher resistance to flow. Water has low viscosity compared to blood.
Viscosity of Blood ∝ Hematocrit
Term
Turbulence
 Definition
As flow streams increase in velocity, a point is reached when laminar flow is disrupted. Flow becomes chaotic.
Flow speed at which turbulence occurs depends on: Density of the fluid. Viscosity. Diameter of the vessel.
Term
Reynold's Number (Re)
 Definition
Unitless number; predicts turbulence.
Reynold's#>2000 turbulence is likely.
Re=inertial forces/viscous forces or
Re=ρDv/η (density.diameter.velocity)/viscosity
Term
Inertia
 Definition
The property that causes a fluid or object to resist a change in direction or speed. Friction, viscosity, & resistance are the foes of inertia.

Objects at rest tend to remain at rest…
Term
Poiseuille's Law
 Definition
Predicts flow in a cylindrical vessel.
Relates Pressure and Flow
Q=ΔPπr^4/8lη
Assumes: Steady-State Flow, Rigid Flow Conduits and Newtonian Fluids. Which doesn't happen in the body.
Term
Resistance Equation
 Definition
R=8lη/πr^4
Term
Simplified Law of Hemodynamics
 Definition
ΔP=Q*R
Term
Ohm’s Law
 Definition
V(voltage)=I(current)x R(resistance)
Compare to: ΔP=Q*R
Term
Bernoulli's Law
 Definition
Total energy at one location must equal all the total energy of another location.
Total energy = potential energy + kinetic energy.
Term
Bernoulli Effect
 Definition
A 75 % area reduction (50% diameter if circumferential) will cause a velocity increase, and a distal pressure decrease.
Velocity ∝ 1/area
Term
“Triggers” for Vasodilation
 Definition
Low oxygen tension in tissue. Increased CO2 levels in tissue.
Increase in lactic acid.
Epinephrine from adrenal medulla.
Increased potassium ions.
Term
Exercise Waveform
 Definition
Normal: From triphasic to low resistance.
Term
Risk Factors for PAD
 Definition
Familial/genetic component (Hx:CVA,TIA,MI). Cholesteral >240 mg/dl. Hypertension. Diabetes mellitus. Severe obesity. Elevated triglycerides. LDL > 160 mg/dl. Depressed fibrinolytic system. Tobacco abuse. Increased oxidation of LDLs. Hx: CVA,TIA,MI.
Term
Mild Occlusive Arterial Disease/PAD
 Definition
Asymptomatic (ASX)
Not hemodynamically significant.
Mild decrease in ankle pressure w/exercise. Athero disease may be seen on US exam, but no flow reduction.
Bruit.
Term
Moderate Occlusive Arterial Disease/PAD
 Definition
Asymptomatic at rest.
Intermittent claudication: Most common symptom of PAD. Pain, fatigue or cramping in calf, thigh or buttock w/exercise. Relieved by rest. Brought on by transient ischemic event in muscles. Exercise causes a significant decrease in ankle pressure.
Term
Severe Occlusive Arterial Disease/PAD
 Definition
Night pain in feet/toes,relieved by dependancy.
Dependant rubor. Ischemic rest pain in feet/toes. Non-healing wounds on feet/toes. Ulceration on lower leg or foot. Tissue necrosis, gangrene.
Term
Other Arterial Pathology
 Definition
Buerger’s disease: Small vessel thrombosis,“fixed” occlusive disease.
Raynaud’s syndrome: Small vessel vasospasm.
Pulsatile Masses -aneurysms & pseudoaneurysms.
Arteritis .
Arterial–venous fistulas (AVF).
Blue Toe Syndrome.
Term
Entrapment Syndromes
 Definition
Structures that extrinsically pinch or constrict arterial flow. Popliteal artery entrapment(claudication-like symptoms). Nutcracker syndrome:renal vein. Median arcuate syndrome:celiac axis. SMA syndrome:SMA. Thoracic outlet syndrome:subclavian or axillary artery.
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