Lecture 5 (Cardiovascular Dysfunction) Flashcards
What is the number 1 killer in sci above cardiovascular disease?
respiratory disease
Are individuals with sci at inc risk of CVD compared to able bodied?
Depends
- since sci so broad
- odds are different depending on injury
- CVD also very broad so depends on type of disease
What is ischemic heart disease? Who is at most risk?
Inadequate oxygen supply tor meet needs of heart, primarily due to occlusion of coronary arteries (Supplying the heart tissues blood and o2) therefore tissue suffers
Complete tetraplegia sci are the only sci injury significantly affected (2.5x more likely to DIE from this disease)
What is the process of ischemic heart disease?
- LDL (bad cholesterol) gets caught in intima
- HDL (Good cholesterol) tries to get rid of LDL by antioxidants reversing oxidation of LDL
- oxidized LDL attracts monocytes
- monocytes turn to macrophages and eat LDL, forming foam cell
- smooth muscle cells from media cover over top “Capping” the foam cells
- cap of smooth muscle cracks, foam cell signals for platelets to mend crack
- platelets signal for more platelets, creating a ball of them (Thrombus)
- Thrombus dislodges (Now an embolus) plugs the artery down stream and alters blood flowing to heart - myocardial infarction/heart attack
Why are individuals with complete tetra at increased risk of death due to ischemic HD?
Lower HDL levels (Due to insulin resistance, altered lipid metabolism - atrophy, etc)
- good cholesterol
- therefore not more bad cholesterol, just less good to fight it off
- HDL ratios are higher in individuals with complete tetra (better to have smaller ratios, since less difference between the two)
Stickier platelets
- Feedforward cycle of platelet aggregation triggering release of PDGF (platelet derived growth factor), causing more aggregation, causing more PDGF, etc making it more “sticky”
- PGI2 inhibits aggregation, but after SCI, there is 50% less binding of PGI2 to plug the receptors on platelets, therefore tougher to slow down aggregation
Obesity
- independent risk factor
Inactivity
- independent risk factor
Silent ischemia
- May not feel chest pain that is normally associated with ischemic HD
Why are some SCI individuals HDL and platelet aggregation equivalent to able bodied?
Since due to inactivity, therefore reversible
-Probably not increased risk strictly due to SCI, just easier to obtain with SCI, but able to fight it
- except silent ischemia
What is non-ischemic heart disease? Who is most at risk?
cardiac dysfunction that is not primarily due to occlusion of coronary arteries
- everything else (Enough blood flow to heart something else happening though)
Incomplete (4x = 2x) and complete tetraplegia (23.4x = 11.7) more likely to die
-likely overestimation
- autopsies will likely rule as non-ischemic, so divide by half (NO LONGER complete paraplegia significant)
What are the two highest risk heart diseases affecting sci?
Congestive heart failure
- Heart works harder to pump
- Since needs to increase blood pressure
- Think of a car door
○ If no pressure/wind, no problem opening door
○ If windy, tougher to open the door
- Left ventricle becomes thicker and muscular since working harder to open that valve to empty the ventricle
○ Becomes pathological/pushes all the time
- Eventually so thick it makes the ventricle smaller/less space for blood, meaning can not pump as much blood,
○ Now cannot supply these tissues with blood
Thicker walls requiring more blood, but less blood able to be pumped
Rhythm disorder
-Imbalance of para and symp nervous systems causing alternate rhythm of heart beats
Are SCI causing congestive heart failure? Why?
Likely due to inactivity
- Also higher BP due to stiffer blood vessels due to edema/swelling pushing on the vessels tightening them up (Difficulty dilating)
- Activity can increase elasticity and dilation of vessels
Are SCI causing rhythm disorders? Why
Not clear
- Could be increased with more activity, not enough research
- Need balance of para and symp nervous systems, but high level SCI throws off sympathetic nervous system and therefore the outflow of the heart, meaning rhythm disorders caused
What is Cerebrovascular disease? Who is at most risk?
Damage to or occlusion of blood vessels that supply the brain (Stroke, brain damage or death)
- Complete tetraplegia most at risk (5.4x more likely to die)
Why are those with tetraplegia increased risk of death due to cerebrovascular disease? Is this risk due to the SCI itself, or can it be reversed?
Susceptibility to autonomic dysreflexia (Large increase in blood pressure in those most commonly with injury at T6 or above)
- Yes due to the SCI, exercise won’t really have an effect on autonomic dysreflexia
What is deep vein thrombosis? Why is it a big problem in SCI?
- Blood flow is more sluggish after SCI
- Tendency for blood to coagulate/clot
- clot forms on wall of blood vessel (Appears red and hot, do not massage)
- Thrombus may detach making embolus (Float down veins which get larger and larger, could float through heart, and then into pulmonary system where the vessels get smaller
- therefore causes rapid breathing, chest pain, bloody cough, PULMONARY embolism
What are diseases of the pulmonary circulation? Who is most at risk and is it due to SCI
Pulmonary embolism
- All types of SCI are highly at risk/increased chance of death (23x - 107x)
- Yes due to sci, exercise may help, depends on sci level, type of disease, and most likely just going to be a slight help
- Such high risk is reason why most are given blood thinners right after SCI
What is orthostatic intolerance?
inability to withstand upright posture (Sitting up or standing up) without experiencing fainting due to extreme drop in blood pressure
- common with t6 or higher
- susceptible since loss of sympathetic drive to stomach and heart, loss of muscle pump
- BP drops since cannot constrict vessels in stomach
