Cardiovascular function after SCI Flashcards
Cardiovascular disease is the:
-number 2 killer in individuals with SCI
-most common killer in through 60 years old or older and those who had an SCI for more than 30 years
What is Ischemic heart disease?
- lack of oxygen to support the heart, often causes by coronary artery occlusion
-incomplete para and tetra and complete para has equal risk
-complete tetra has an increased risk due to cholesterol
The three main culprits of Occlusion of coronary artery?
1.LDL, low density lipoprotein, the bad type of cholesterol
2. HDL, high density lipoprotein, good type of cholesterol
3. monocytes: found in white blood cells, the protector in a way
What are the 3 layers of blood vessels?
1.intima: endothelial cells, closest to wall
2. media: smooth muscle cells
3.adventitia: connective tissue
What happens during occlusion of coronary artery?
-LDL dips in and out of intima layer, then it gets stuck and becomes oxidized, HDL transports antioxidants which reverses LDL typically
- then the monocytes (white blood cells) go in and try and get the LDL
-the monocytes mature causing macrophages which eats the oxidized LDL, which then turns into a foam cells
-foam cells collect, causing the smooth cells (from media) to move into the intima layer which narrows the artery due to bulge forming and making a cap
- the cap then cracks open and the platelets get signalled in to fix the crack
-plateletes signal more platelets creating a ball of platelets (thrombus)
- then the thrombus dislodges (embolus) which causes plug of the artery and an MI
Complete tetraplegia and increased risk from IHD:
1) individuals with comp tetra have lower HDL levels, not more LDL just less HDL, total cholesterol ratio, you want a low number not high but comp tetra have higher ratios
2) Individuals with SCI have stickier platelets
a) platelets sticking to each other facilitated by platelet derived growth factor (PDGF)
-more prone to platelet aggregation
platelet aggregation–>release of PDGF–>platelet aggregation (makes a feedforward cycle)
-blood PDGF levels in SCI are 3x greater than able bodied people
-PDGF also causes smooth muscle migration into intima
b) platelet aggregation is inhibited by prostacyclin (PG12)
- prostacyclin–> stops stickiness
-less prostacyclin = more sticky
-after SCI there is a 50% less binding of PGI2 to platelets due to loss of PGI2 receptors
3)obesity (independent risk factor for IHD)
-individuals with comp tetra are more likely to be obese
4)Inactivity (independent risk factor)
-individuals with comp tetra are more likely to be inactive
5)silent ischemia- don’t feel the chest pains (angina) in comp tetra
Is the risk for comp tetra for IDH from the SCI?
-SCI athletes have HDL levels that are equivalent to able bodied, this means it is due to inactivity, it is reversible with exercise (increase HDL)
-exercise training is associated with reducing resting platelet aggregation- the reduction is partially due to an increase in prostacyclin (PGI2 levels)
-individuals with comp tetra are at a higher risk for death from IHD
What is non-ischemic heart disease?
-cardiac dysfunction that is not primarily due to an occlusion of the coronary arteries
-incomp para is same risk
-comp para, incomp tetra and comp tetra have increased risks, worse risk with worse sci
What are the different types of NIHD?
- congestive heart failure
- rhythm disorders
What is congestive heart failure?
-heart stops working harder than normal to pump due to increased blood pressure
-when it pumps the valve has to be opened, so with high BP the left ventricles have to work very hard, then it gets bigger and stronger and thicker and more muscle
-so much muscle is there and there is not enough blood to meet the thick muscle wall
Risk for tetra due to?
- atrophy of the peripheral blood vessels
-stiffening of the peripheral blood vessels
-increased total peripheral resistance (like opening car door in the wind)
-the blood vessels get smaller and stiffer
What are Rhythm Disorders?
-stiffening of blood vessels after SCI from edema
-healthy able bodied: blood is fast and goes right through
-after SCI- blood is sluggish–> fluid accumulates causing swelling from sluggish flow- there is pressure on both sides of blood vessel
increased risk for tetraplegia: disturbance to autonomic outflow to the heart, imbalance of sympathetic and parasympathetic
Individuals with tetra are at a higher risk for death CHF and rhythm disorders due to?
- increased total peripheral resistance
- disturbance to the autonomic outflow to heart
What is cerebrovascular disease (stroke)?
-damage to or occlusion of the blood vessels that supply the brain–>stroke–>brain–>damage or death
risk for comp tetra:
-susceptibility to autonomic dysreflexia, condition most common in individual switch injuries at T6 or higher, characterized by large increases in blood pressure
What is increased risk of deep vein thrombosis (DVT)?
-Sluggish blood flow, blood coagulates and causes a clot, when the blood vessel with clot is stuck to wall it causes a thrombosis, if it detaches (embolus) it can migrate to the lungs causing a pulmonary embolism
-when the clot form its thrombus, DVT–>hot, redness, don’t massage
-pulmonary embolism–> rapid breathing, chest pain, bloody cough, call 911
