exercise physiology clinical application

Question 1

factors affecting O2 supply

Answer 1

1) coronary blood flow
- perfusion pressure
- vascular resistance

2) O2 content

Question 2

factors affect O2 demand

Answer 2

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

Question 3

how does O2 extraction change with exercise

Answer 3

minimal incr O2 extract

Question 4

factors decr O2 supply

Answer 4

Hypotension (MAP

Question 5

factors affecting coronary vascular resistance

Answer 5

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

Question 6

a

Answer 6

a

Question 7

factors incr O2 demand

Answer 7

1) exercise
2) fever
3) acute HTN
4) emotional distress
5) cardiac disease (LVH)
6) drugs- amphetamines/cocaine

Question 8

consequences of myocardial ischemia

Answer 8

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)

Question 9

what determines when O2 supply decr

Answer 9

severity of coronary stenosis

rest: need 90% stenosis
exercise: coronary blood flow decr with 70% stenosis

Question 10

a

Answer 10

a

Question 11

a

Answer 11

a

Question 12

what causes ST depression during exercise

Answer 12

decr intracellular K+ in subendocardium (early repol)

Question 13

a

Answer 13

a

Question 14

determinants of myocardial O2 demand with exercise (MVO2)

Answer 14

1) incr systolic BP, incr wall stress and contractility

2) incr HR

Question 15

what is RPP

Answer 15

rate-pressure production

RPP = HRmax x SBPmax 
RPP = HR^2 x SV x SVR

HR is most important

Question 16

equation for SVR

Answer 16

SVR = MAP/CO

Question 17

define ischemic threshold

Answer 17

RPP where ischemia occur

inadequate supply to meet demand

Question 18

what does ischemic threshold depend on

Answer 18

1) severity of coronary stenosis (fixed RPP)

2) abnormal coronary vasomotion (variable RPP) = varying activities causing angina

Question 19

more severe ischemia occurs at ___ RPP

Answer 19

lower RPP

Question 20

relationship btwn workload and RPP

Answer 20

incr workload, incr RPP LINEARLY

until threshold –> when supply can’t meet demand

Question 21

effect of beta blocker on MVO2

Answer 21

can exercise longer time and do more work before reach SAME RPP

Question 22

effect of PCI on MVO2

Answer 22

can INCR RPP

Question 23

exercise testing protocols

Answer 23

1) staged

2) ramp = gradual incr in HR and BP (RPP)

Question 24

a

Answer 24

a

Question 25

how does severe myocardial ischemia affect SV during exercise

Answer 25

decr SV with incr workload exertional hypotension ~ severe CAD

Question 26

what happens if you have decr HR response during exercise

Answer 26

chronotropic incompetence = severe CAD

Question 27

define chronotropic index

Answer 27

how abnormal patient's HR is normal > 80% more severe CAD, decr max HR

Question 28

a

Answer 28

a

Question 29

Benefits of exercise training on coronary artery physiology for patients with CAD

Answer 29

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

Question 30

a

Answer 30

a

Question 31

how does exercise affect peak VO2

Answer 31

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

Question 32

a

Answer 32

a

Question 33

a

Answer 33

a

Question 34

effect of exercise on altering ischemic threshold in CAD patients

Answer 34

1) uncommon to alter threshold- 2) High RPP when ischemia occurs 3) incr myocardial perfusion 4) less vasoconstriction

Question 35

people with CAD ____ more than people without during exercise

Answer 35

vasoconstrict

Question 36

a

Answer 36

a

Question 37

mechanisms of improved perfusion with exercise training (4 things)

Answer 37

1) corrects endothelial dysfunction 2) regress atherosclerosis 3) collaterals 4) vasculogenesis by bone marrow stem cells

Question 38

if reach anaerobic threshold sooner, then ___

Answer 38

more CAD

Question 39

what is RER

Answer 39

RER = respiratory exchange ratio = ratio btwn CO2 production | and O2 consumption, —> high intensity exercise (anaerboic sooner)

Question 40

a

Answer 40

a

Question 41

a

Answer 41

a

Question 42

a

Answer 42

a

Question 43

equation for VO2 in terms of CO

Answer 43

VO = CO x a-v O2

Question 44

equation for CaO2 or CvO2

Answer 44

CaO2 = [Hgb] x 1.34 x O2 sat

Question 45

why to use exercise training in chronic systolic HF

Answer 45

1) assess functional limitations 2) predict prognosis in severe HF 3) pre-transplant eval

Question 46

hemodynamics of LV systolic dysfunction at rest

Answer 46

1) incr HR, incr EDV, ESV, incr preload and afterload 2) decr SV, LVEF 3) normal or decr CO

Question 47

hemodynamics of LV systolic dysfunction at exercise

Answer 47

1) limited incr CO, SV, HR, HR reserve (peak - rest) 2) high cardiac filling P = dyspnea 3) limited vasodilation

Question 48

what is HR reserve

Answer 48

peak HR - rest HR narrowed with CAD because resting HR higher to compensate for lower SV and decr peak HR due to abnormal sympathetic

Question 49

peak VO2 is more closely related to ___

Answer 49

cardiac output than O2 extraction so good assessment with stress test in HF

Question 50

___ is more closely related to cardiac output than O2 extraction

Answer 50

peak VO2

Question 51

functional HF class based on VO2 correlates with ___ patients

Answer 51

chronic heart failure

Question 52

___ influences 1 yr survival in patients with severe LV systolic dysfunction

Answer 52

peak VO2 decr peak VO2, decr survival with systolic HF