12.3

Question 1

panel 2 shows

Answer 1

HR and vo2/HR (oxygen pulse)

Question 2

panel 2

Answer 2

heart rate (HR) and VO2/HR versus time and work rate

Question 3

VO2/HR is

Answer 3

O2 pulse

Question 4

O2 pulse =

Answer 4

stroke volume x arteriovenous O2 difference

Question 5

what is HR and VO2/HR for patients with certain CV defects

Answer 5

HR is high and vo2/HR is low for a given work rate

Question 6

o2 pulse is used as a surrogate of

Answer 6

Stroke volume

Question 7

when could O2 pulse could be normal or high

Answer 7

with chronotropic incompetence or B-adrenergic blockade without systolic or diastolic dysfunction

Question 8

whats without systolic or diastolic dysfunction

Answer 8

good squeeze, good relaxation
no Hfpef or Hfref

Question 9

why is O2 pulse normal for person with chronotropic incompetence or β-adrenergic blockade without systolic or diastolic dysfunction

Answer 9

Hr slower
diastolic filling time longer

Question 10

the O2 pulse is calculated by

Answer 10

dividing the VO2 by the simultaneously measured HR

Question 11

what is oxygen pulse

Answer 11

the volume of O2 taken up by the pulmonary blood during the period of a heart beat and depends on the volume of o2 extracted by the peripheral tissues

Question 12

why is the measurement of O2 pulse useful

Answer 12

because it equals the product of SV and the arterial-mixed venous O2 difference [C(a-v)O2]

Question 13

the immediate increase in O2 pulse at start of exercise depends

Answer 13

primarily on the increase of stroke volume

Question 14

later on what is O2 pulse mediated by

Answer 14

A-VO2 diff when continuing to rise (O2 extraction at muscle)

Question 15

as the work rate is increased, the O2 pulse

Answer 15

increases, primarily because of an increasing C(a-v)O2

Question 16

if stroke volume is reduced and the C(a-v)O2

Answer 16

the O2 pulse reach maximal values at a relatively low work rate

Question 17

when o2 pulse reaches max values at relatively low work rate the O2 pulse has a

Answer 17

low asymptote (plateau)

Question 18

O2 pulse is low in subjects with

Answer 18

anemia, high levels of carboxyhemoglobin, marked arterial hypoxemia, and muscle mitochondrial or glycolytic enzyme defects because of reduced C(a-V)O2 at max exercise

Question 19

stroke volume is estimated from the O2 pulse by the following equation

Answer 19

SV= (O2 pulse/C(a-v)O2) x 100

Question 20

when is the O2 pulse measured breath by breath informative

Answer 20

in transition from rest to exercise and from exercise to recovery

Question 21

increase in O2 pulse at start of exercise depends on

Answer 21

the size of the stroke volume increase and the increase in C(a-v)O2

Question 22

increase of O2 pulse at start of exercise will be low in patients

Answer 22

who cannot increase their SV in response to exercise

Question 23

what happens to O2 pulse in normal subject when stopping exercise

Answer 23

O2 pulse promptly decreases

Question 24

what happens to O2 pulse in patients with left ventricular failure (LVF) and exercise induced myocardial ischemia when stopping exercise

Answer 24

transiently increases

Question 25

what is the explanation for increase of O2 pulse in patients with CV problems

Answer 25

the afterload of the LV is abruptly decreased when stopping exercise because of the immediate decrease in systemic arterial BP

Question 26

what does this allows for the patient with the failing heart stops exercising

Answer 26

allows improved ventricular ejection and increased SV

Question 27

What does the increase in SV do for patient with failing heart at stopping of exercise

Answer 27

allows capillary blood flow to move more rapidly through the lung during the period of a heartbeat, thereby absorbing more O2

Question 28

overview of why O2 pulse stays high for failing heart

Answer 28

terrible squeezing with increased afterload so as soon as stop exercise afterload decreases and resistance decreases SV really increases

Question 29

patients with low SVs such as those with heart disease tend to have

Answer 29

low O2 pulse values at maximal exercise

Question 30

arteriovenous O2 difference is

Answer 30

oxygen extraction

Question 31

what is the highest atriovenous O2 diff score

Answer 31

20

Question 32

what is relationship of A-VO2 diff between healthy person and chronic heart failure at peak exercise

Answer 32

not very different 16.2 in normal, 15.0

Question 33

why is heart failure patient similar to healthy for AVO2 diff at peak exercise

Answer 33

thought to be because of low CO transit time of RBCs will be slower more time for O2 to diffuse across capillary bed, more offloads

Question 34

black diamonds is

Answer 34

O2 pulse/HR

Question 35

White circles is

Answer 35

HR

Question 36

questions answered in panel 2

Answer 36

what is resting HR what is peak HR what was VO2/HR at peak exercise

Question 37

what does panel 2 have for axis

Answer 37

2 y axis

Question 38

expect O2 pulse to rise

Answer 38

linearly

Question 39

know its end of exercise when O2 pulse values

Answer 39

drop

Question 40

at end of exercise in healthy control

Answer 40

O2 pulse and HR recover immediately

Question 41

recovery for other patients

Answer 41

O2 pulse slow in all except normal heart

Question 42

what to expect with healthy O2 pulse

Answer 42

expect linear, fairly steep rise and at termination should come down immediately

Question 43

what can assume if O2 pulse decreases before end of exercise

Answer 43

deflection because not linear, can assume cardiac dysfunction occured

Question 44

expected HR

Answer 44

linear

Question 45

very exercise intolerant

Answer 45

HR high at beginning

Question 46

if O2 pulse linear

Answer 46

no exercise intolerance

Question 47

slow rise or shallow of o2 pulse indication of

Answer 47

CV disease

Question 48

panel 2: HR normally

Answer 48

increases abrubtly at the start of unloaded cycling and then increases approximately linearly with work rate to the predicated maximal HR

Question 49

May have low HR if

Answer 49

terminated exercise early

Question 50

panel 2: normal O2 pulse

Answer 50

increases but with a gradual decreasing rate of rise

Question 51

O2 fails to increase normally in patients with

Answer 51

reduced SV and therefore reduced exercise capacity

Question 52

the value of peak O2 during exercise is

Answer 52

abnormally low in CV patients