Week 2 Flashcards
Blood follows a path of?
Least resistance
What affects resistance in regards to hemodynamics?
Length and width
If blood were presented with two paths, a short and narrow one or a long and wide one, which path would it take?
The long and wide–the path of least resistance.
The most common collateral pathways involve the ______________.
Circle of Willis
What are 3 major collateral routes?
Other side of CoW
Posterior cerebral circulation
External carotid artery branches
Describe the pathway that blood can flow from the left hemisphere from the other side of the circle:
Right CCA→ rt. ICA → rt. ACA→ across the anterior communicating artery→ retrograde down the left ACA→ lt. MCA→ lt. hemisphere
Describe the alternate pathway that may originate from the posterior circulation:
Vertebral artery flow enters the basilar artery→ lt. posterior cerebral artery→ left posterior communicating artery→ distal lt. ICA→ lt. MCA
Describe the alternate pathway that may originate from the external carotid circulation:
Lt. ECA → ECA branch (superficial, temporal, maxillary or facial) → retrograde down an ICA branch (supraorbital, nasal or frontal) → continue to retrograde flow down the ophthalmic artery → carotid siphon → MCA → lt. hemisphere
What is the second most important source of collateral flow?
Anastomosis between branches of the ECA and ICA via orbital and ophthalmic arteries
What are the 6 intracranial-extracranial anastomoses?
Lacrimal Supraorbital Anterior/Posterior ethmoidal Medial Palpebral Frontal Dorsal Nasal Artery
The normal flow in the ophthalmic artery is retrograde and if there is an occlusion present, it will become antegrade flow. True or false
False
Adequate arterial perfusion relies on what? (3)
Cardiac output
Blood volume
Systemic blood pressure
If circulation is compromised, what can this lead to?
Hypoxia or anoxia
Why do collaterals develop?
Because of a change in the pressure gradient between the vessels, caused by a stenosis
If the pressure drops enough to attract flow from a vessel sitting further down the line, blood vessels may abandon their normal routes and take advantage of the new, lower pressure route. What is an example of this phenomenon?
SSS
In older individuals what can we see with their collateral pathways?
Hypoplastic or atherosclerotic
What branches of the ECA can be collaterals?
Superficial
Maxillary
Facial
Temporal
What branches of the ICA are involved in the ECA collateral circulation?
Facial
Nasal
Supraorbital
What is most essential to determine when examining the vertebrals?
Presence/absence of flow
Direction of flow
Vertebral basilar system provides 20-30% of cerebral blood flow. True or false
True
If there’s a vertebral occlusion, where is the blood flow shunted? (2)
Thyrocervical trunk
Costocervical trunk
Where do the vertebral arteries arise from?
Subclavian arteries
Basilar artery connects to the CoW via what vessel?
PCAA
What is nystagmus?
Rapid involuntary movement of the eye
Vertebral flow is low or high resistance?
Low
What is the normal velocity for the vertebrals?
20-60cm/s
Which vertebral artery is more readily seen?
Right
L=larger
R=readily seen
Which vertebral artery is commonly larger?
Left
SSS is most often seen on which side?
Left
What amount of pressure difference is there between two arms when SSS is present?
20-40mmHg
slides are either saying 20 or 40, so maybe just know both
What’s the typical PSV in the SCA when there’s a SSS?
> 400cm/s
Loss of normal triphasic waveform
One slide also said 500 so IDK
A syndrome is what?
The aggregate of signs, symptoms or other manifestations to constitute the characteristics of a morbid entity.
What can make an increase in pressure drop greater following a stenosis?
Exercise
Why does blood reverse down the vertebral artery as a result of SSS?
A drop in pressure in the SCA falls below the junction of the 2 vertebral arteries, therefore it becomes easier for blood to flow in a retrograde fashion.
Pressure gradient
Why is SSS potentially harmful?
There may be a reduction of blood flow to the brain which can result in symptoms of vertebrobasilar insufficiency
Why will a right sided innominate artery stenosis have more of an impact on cerebral hemodynamics?
Because of the involvement of the right CCA
Ultrasound is a very accurate modality in diagnosing SSS. True or false
True– 90-100%
If you see a reversal of flow in the vertebral artery, this is one of the first signs of SSS. True or false.
False– it is the final stage
Prior to constant flow, there is a deceleration of antegrade flow during systole and only retrograde flow in diastole
Usually seen better in periods of exercise
What is reactive hyperemia?
Temporary increase of blood flow that occurs following a brief period of ischemia
When a patient has a SSS, what do they clinically present with?
Loud supraclavicular bruit
Reduced pulse in affected arm
Reduce BP in affected arm
Which arm has decreased pressure?
Ipsilateral
Because of the stenosis, the SCA will now have a triphasic waveform. True or false
False– it normally has a triphasic waveform and will now appear damped (monophasic)
What does the loss of high resistant, high pulsatility flow of the distal SCA indicate?
The proximal SCA has an occlusion or stenosis.
What is thoracic outlet syndrome?
When the subclavian artery and brachial nerve plexuses become compressed
Can lead to limb ischemia
An entrapment syndome
What is Paget-Schroetter syndrome?
Effort induced DVT of the upper extremity veins in young patients
Classified as TOS
What does TOS present as clinically?
Upper extremity circulation problem
Cold, painful or numb extremities
Can vary with limb positioning–if they lift the arm up it will show symptoms
Repeated irritation of TOS can cause thrombus formation in which can travel to the distal parts of the arm. True or false
True
Uncomplicated TOS means what?
No thrombus, plaque or aneurysm formation
Nerve compression
What are the patient positions when scanning for TOS?
Segmental BP and pulse volumes are obtained with:
Arm in neutral position
Arm in position that causes symptoms
Arm in extreme positions
What will be seen in patients with TOS? (signals)
The radial artery signal goes flat
If there are no changes in Doppler signal or PVR waveforms the exam is over and TOS is negative
What is popliteal artery entrapment?
Common site for entrapment syndromes in young athletes
Hyperextension of the knee or plantar extension can cause diminished flow in the calf and foot due to compression by the medial head of the gastrocnemius muscle
In popliteal entrapment syndrome, what amount of pressure drop will be seen?
20 mmHg
What is anterior compartment syndrome?
Where trauma (sports injuries or car accidents) can result in arterial compression and subsequent ischemic distal to the site of compression can occur
What is blue toe syndrome?
One of the most frequent manifestations of tissue ischemia
Caused by occlusion of small vessels
Usually caused by cholesterol crystals or a lump of plaque getting stuck in small vessels
If blue toe syndrome is left untreated, what can occur?
Gangrene
Who does blue toe syndrome usually occur in?
Elderly men who undergo an invasive vascular procedure
Develops suddenly and rapid
Usually only one foot
What is the diagnostic tool of choice for blue toe syndrome? (2)
US
CTA
What are the treatment options for blue toe syndrome?
Stenting
Bypass surgery
Anti-coagulants/anti-platelet
Who is more likely to have Raynaud’s disease, men or women?
Women
What is Raynaud’s disease?
Causes some area of the body such as fingers and toes, to feel numb and cold in response to cold temperatures or stress
Smaller arteries that supply blood to the skin narrow, which limits the blood circulation to affected areas
In Raynaud’s disease, the smaller arteries limiting blood to affected areas is because of vasospasm. True or false
True
What are the changes of color in the skin in a Raynaud’s disease attack?
White-first
Blue- cold and numb
Red- as you warm and circulation comes back, it may feel tingly and swollen
What is the difference between primary and secondary Raynaud’s disease?
Primary- more common. Not the result of an underlying associated medical condition that causes vasospasm
Secondary- caused by an underlying problem. Tends to be more serious
Which type of Raynaud’s disease typically shows symptoms later in life?
Secondary– around 40yrs
What are some conditions that can cause secondary Raynaud’s disease?
CT disease: scleroderma, lupus, rheumatoid arthritis, Sjorgen’s syndrome
Atherosclerosis, Buerger’s disease and pulmonary hypertension
Carpal tunnel syndrome, RSI’s, smoking, fractures and certain medications
What is the test in diagnosing Raynaud’s disease?
Cold test– hands are placed in water until symptoms appear and then a device measures how long it takes the fingers to return to normal body temperature
What is nutcracker syndrome?
The compression of the left renal vein between the SMA and aorta
What can result from nutcracker syndrome?
Renal venous hypertension–resulting in the rupture of thin walled veins into the collecting system with resultant hematuria
What are splanchic vessels?
Consists of the blood supply to the gastrointestinal tract, liver, spleen, and pancreas
What can be caused from nutcracker syndrome?
Nausea and vomiting
Unusual manifestation of varicocele formation and varicose veins in the lower limbs
What are the signs of nutcracker syndrome?
Lt renal enlargement Persistent hematuria Proteinuria Hypertension RV thrombus
What are the surgical approaches for NCS?
Nephrectomy
Nephropexy
Renocaval reimplantation
Intravascular stent
What are the 3 main symptoms of Leriche syndrome?
Claudication
Impotence
Decreased pulses to lower limbs
What is Leriche syndrome?
Blockage in the lower part of the aorta just before the starting point of the common iliac arteries
Blood supply to lower limbs and groin is reduced
What are risk factors for Leriche syndrome?
Atherosclerosis
Smoking
What’s another term for Leriche Syndrome?
Aorta iliac occlusive disease
What aids in the diagnosis of Leriche syndrome?
Ankle brachial index
Arterial doppler study of aorta/iliac region
Distal/bif will be occluded
What is Marfan’s syndrome?
Genetic disorder that affects the body’s connective tissue
Valvular heart disease that causes a thickened mitral valve leaflet displacement
What parts of the body can be affected by Marfan’s?
Heart, blood vessels, bones, joints and eyes
What can occur from Marfan’s syndrome?
Aortic aneurysm and dissection
What do people with Marfan’s syndrome look like?
Long arms and legs
Thin
Tall
Long thin fingers
