exercise physiology clinical application Flashcards
factors affecting O2 supply
1) coronary blood flow
- perfusion pressure
- vascular resistance
2) O2 content
factors affect O2 demand
1) wall stress (P x r / (2h))
P = sys P
r = radius of LV
h = wall thickness
2) HR
incr # contraction, incr # ATP
3) contractility
incr by sympath stim
how does O2 extraction change with exercise
minimal incr O2 extract
factors decr O2 supply
Hypotension (MAP
factors affecting coronary vascular resistance
1) external compression
- intramyocardial pressure = highest in systole
- subendocardium more vulnerable
2) intrinsic regulation
- local metab (adenosine vasodilate)
- NO, EDHF (vasodilate) vs. endothelin 1 (vasoconstriction)
- alpha + b2 receptors
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factors incr O2 demand
1) exercise
2) fever
3) acute HTN
4) emotional distress
5) cardiac disease (LVH)
6) drugs- amphetamines/cocaine
consequences of myocardial ischemia
1) angina
2) ST depression (decr intracellular K+)
3) decr systolic fxn, decr SBP
decr diastolic fxn, incr wedge pressure
mitral regurg
4) incr HR, BP (sympath)
what determines when O2 supply decr
severity of coronary stenosis
rest: need 90% stenosis
exercise: coronary blood flow decr with 70% stenosis
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what causes ST depression during exercise
decr intracellular K+ in subendocardium (early repol)
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determinants of myocardial O2 demand with exercise (MVO2)
1) incr systolic BP, incr wall stress and contractility
2) incr HR
what is RPP
rate-pressure production
RPP = HRmax x SBPmax RPP = HR^2 x SV x SVR
HR is most important
equation for SVR
SVR = MAP/CO
define ischemic threshold
RPP where ischemia occur
inadequate supply to meet demand
what does ischemic threshold depend on
1) severity of coronary stenosis (fixed RPP)
2) abnormal coronary vasomotion (variable RPP) = varying activities causing angina
more severe ischemia occurs at ___ RPP
lower RPP
relationship btwn workload and RPP
incr workload, incr RPP LINEARLY
until threshold –> when supply can’t meet demand
effect of beta blocker on MVO2
can exercise longer time and do more work before reach SAME RPP
effect of PCI on MVO2
can INCR RPP
exercise testing protocols
1) staged
2) ramp = gradual incr in HR and BP (RPP)
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how does severe myocardial ischemia affect SV during exercise
decr SV with incr workload
exertional hypotension ~ severe CAD
what happens if you have decr HR response during exercise
chronotropic incompetence = severe CAD
define chronotropic index
how abnormal patient’s HR is
normal > 80%
more severe CAD, decr max HR
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Benefits of exercise training on coronary artery physiology for patients with CAD
1) incr peak VO2, incr peripheral O2 extract, incr SV
2) decr sympathetic and decr HR/BP at submaximal exercise, decr myocardial VO2
3) no change in total body VO2
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how does exercise affect peak VO2
1) decrease metabolic activity (decr myocardial O2 demand)
2) can do more work before reach ischemic threshold
3) decr RPP
4) minimal incr in O2 extraction
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effect of exercise on altering ischemic threshold in CAD patients
1) uncommon to alter threshold-
2) High RPP when ischemia occurs
3) incr myocardial perfusion
4) less vasoconstriction
people with CAD ____ more than people without during exercise
vasoconstrict
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mechanisms of improved perfusion with exercise training (4 things)
1) corrects endothelial dysfunction
2) regress atherosclerosis
3) collaterals
4) vasculogenesis by bone marrow stem cells
if reach anaerobic threshold sooner, then ___
more CAD
what is RER
RER = respiratory exchange ratio = ratio btwn CO2 production
and O2 consumption, —> high intensity exercise (anaerboic sooner)
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equation for VO2 in terms of CO
VO = CO x a-v O2
equation for CaO2 or CvO2
CaO2 = [Hgb] x 1.34 x O2 sat
why to use exercise training in chronic systolic HF
1) assess functional limitations
2) predict prognosis in severe HF
3) pre-transplant eval
hemodynamics of LV systolic dysfunction at rest
1) incr HR, incr EDV, ESV, incr preload and afterload
2) decr SV, LVEF
3) normal or decr CO
hemodynamics of LV systolic dysfunction at exercise
1) limited incr CO, SV, HR, HR reserve (peak - rest)
2) high cardiac filling P = dyspnea
3) limited vasodilation
what is HR reserve
peak HR - rest HR
narrowed with CAD
because resting HR higher to compensate for lower SV and decr peak HR due to abnormal sympathetic
peak VO2 is more closely related to ___
cardiac output than O2 extraction so good assessment with stress test in HF
___ is more closely related to cardiac output than O2 extraction
peak VO2
functional HF class based on VO2 correlates with ___ patients
chronic heart failure
___ influences 1 yr survival in patients with severe LV systolic dysfunction
peak VO2
decr peak VO2, decr survival with systolic HF
