10 and 11 - Peripheral Vascular Disease Flashcards
What is peripheral vascular disease?
- Any compromise of the circulation outside of the heart
Arterial
- Occlusive vs. Functional
- Peripheral Arterial Occlusive Disease (PAOD) = most common vascular disease
Venous
- Varicose veins
- Valve disease
Etiology of arterial vascular disease
- Atherosclerosis (narrowing of the artery) = most common etiology
- Mechanical occlusive disorders
o Thrombi (clot)
o Emboli
o Hematological disorders - Vasculitis and arteritis = acute problem of inflammation
- Buerger’s Disease (thromboangiitis obliterans) = related to smoking, very severe arteritis
- Vasospastic disorders = Raynaud’s is the most common (functional problem)
- Combination of factors listed above
Arterial atherosclerosis
- Intimal and smooth muscle proliferation
- Accumulation of matrix & lipids
- Results in narrowing, hardening or weakening
- Provides nidus for thrombus
- Provides source of emboli
Atherosclerosis risk factors
- Hypertension, hyperlipidemia
- Diabetes
o Most common occlusion is under popliteal at the “trifurcation”
o Diabetics tend to develop more severe peripheral arterial disease at a younger age - Advanced age, male Gender
- Family History
- Stress
Clinical manifestations of PVD
- Diminished or absent pulses due to arterial occlusion
- Pain
o 1st = Leg pain with walking (claudication)
Claudication is a problem with exercise, but they may never have an ulcer form
o 2nd = Ischemic rest pain
A progression from claudication – more severe, critical ischemia*** - Slow healing wounds and tissue damage (ulcer or gangrene)
Clinical indicators of the quality of distal perfusion
- Pulses and capillary refill time
- Skin color and temperature
o Rubor on dependency (purple legs when they are hanging down)
– Due to ischemia and toxic byproducts in the skin
– When you elevate this foot, it will rapidly become very white (pallor)
o Pallor on elevation (Buerger’s sign)
– When the elevated foot is white (pallor)
o Acrocyanosis (bluish or purple coloring of the hands and feet caused by slow circulation) - Skin tone and turgor (hydration)
- Hair growth on toes (hair needs oxygen to grow) and status of nails
- Presence of tissue injury (gangrene, ulcers)
o Gangrene a type of necrosis caused by a critically insufficient blood supply
Ischemic ulcers
- Dry, distal ulcers that cause severe pain (unless neuropathy is present in the limb)
o Ischemia is typically painful (same as a heart attack) - Ulcers have irregular edges, poor granulation (new tissue formation) and exhibit little bleeding with manipulation (by definition, little blood is present)
o Other signs of arterial insufficiency present as well - Generally you do NOT debride the tissue right away – priority infection/circulation assessment
Clinical features of ischemic ulceration
o Distal extremities (as we get more distal, the arterial system is smaller, more vulnerable)
o Full thickness (through all layers of skin)
o Dry necrosis (unless infected) with poor granulation
o Variable locations and spontaneous expansion of affected areas
o Poor pedal pulses and Doppler signal
Associated findings with ischemic ulceration ***
o Pain (claudication, night pain, rest pain)
o Dependent rubor, elevation -pallor
o Skin atrophy and nail dystrophy
o Decreased skin temperature
REVIEW - arterial ulcers
- Distal extremities, full thickness ulceration
- Dry necrosis with poor granulation
- Spontaneous expansion
- Pain, atrophy, pallor and rubor
- Poor pulses and Doppler
Arterial thrombus
- In situ (local) clotting occluding the vessel
- Gradual onset of worsening ischemia
- Signs of arterial disease
- Atheroma already present
Arterial embolus
- When a portion of a proximal plaque breaks off and continues to flow until it reaches an artery that it can’t fit through
- Sudden and severe ischemic symptoms
- No preexisting arterial symptoms
- Identifiable source of free body (atrial fib)
- Signs of PAOD not necessarily present
Embolus pathology
- Proximal atheroma or clot (thrombus) breaks off and floats distally, causing an acute onset
- Ischemic damage is based on the distribution of the occlusion
- Pulses may be normal and 85% of emboli are cardiac in origin (A-fib)
What to focus on so far
NEED TO KNOW THE CLINICAL SIGNS AND SYMPTOMS OF THE OCCLUSIVE PHENOMENONS
Raynau’d phenomenon
- FUNCTIONAL arterial problem
- Epidemiology
o 2% of the population experiences Raynaud’s phenomenon - Pathophysiology
o Episodic reduction in peripheral blood flow in response to cold exposure or stress
o This is NOT an occlusive (atherosclerotic) disorder, but rather a vascular malfunction - Skin color changes
o White – ischemia from vasoconstriction
o Blue – venous stasis
o Red – hyperemia - Sensory changes
o Pain and paresthesias (“pins and needles”) - Treatment
o Nifedipine
o V Prostacyclin or prostaglandin E1 for severe cases
o Evening primrose oil
Venous ulceration anatomy
- Arterial system
o High pressure system of blood “in flow” - Venous system
o Low pressure system of blood “out flow”
o Includes superficial veins, deep veins, perforating veins, all with one way valves - Valves
o Veins have one-way bicuspid valves opening to the deep system
o The valves close when pressure rises in the deep system preventing retrograde flow
o Transmission of elevated pressure to the superficial veins
Venous pressure
- Normal Resting Venous Pressures at ankle in standing position is 60-90mmHg
- Venous insufficiency increases the pressure and amount of blood in the venous system (pooling)
- High pressure induces mechanical and physiologic effects in the vein w/ secondary skin changes
Venous pump in foot and calf
o This is the primary mechanism to return venous blood to the heart
o “Calf pump” muscle contraction can increases venous pressure, to force blood to the heart, but more and more research is pointing to a greater role of the “foot pump”
o Emptying the deep system decreases venous pressure, opening the valve and forcing blood from the superficial to the deep system
Foot pump history and anatomy
o Le Dentu 1869
– Recognized venous foot pump, hypothesized muscular activity powers pump
o Gardner 1989
– Venous emptying occurs prior to muscular contraction in gait
– Clarified the motor of the pump to be direct compression and/or stretching of the veins in the sole of the foot
– Correlates with clinical observations of improved post-traumatic and surgical swelling with early ambulation
Hemodynamics of foot pump
o Impulse pumping causes a sudden rise in venous pressure which causes a greater percentage of the venous capillary loops to open causing proximal drainage
o Direct stretching and compression of the plantar foot veins is the mechanism (NOT Muscular)
– This is a DIRECT mechanical function NO muscular function
– ***This means that it is very important for your venous patients to be walking
o Powerful enough to displace a column of blood from the LE to the heart
o Venous pump is powerful enough to move blood past a 100mm/hg cuff
o Venous priming opens closed arterial capillaries and reduces tissue pressure
– Hyperemic flow lasts 20 seconds after each impulse and increases popliteal artery flow by 93% in normal arteries and 84% in PAOD
– Local release of endothelium derived relaxing factor dilates vessels and increases capillary flow
Pressure-induced vein pathology
- Dilation of venous system (varicose veins) and increased venous permeability lead to fluid retention (pooling of blood)
- There will be bi-directional flow (valve failure) and shunting of blood from deep to superficial
Venous insufficiency physiology
- Varicose veins = genetics, standing, high abdominal pressure
- Incompetence of valves = aging, genetic defects, DVT
o DVT: the clot forms around the valve, so even after the DVT is resolved, the valve is ruined and no longer prevents blood from pooling in the lower extremity, leads to residual edema in the leg and foot - Pump failure = age, arthritis, immobility
Venous ulcer pathophysiology
- Arterial-venous shunting
- Fibrin cuff theory
- White blood cell trapping theory
Arterial-venous shunting
o Fistulae divert blood away from dermis = Ischemia
o If you have higher pressure in the venous system, there is less flow in the arterial system, meaning you will have ischemia
