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Flashcards in Cardiac Mechanical Deck (27)
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1
Q

Timing of Systole and diastole

A
  1. Atrial systole- squeezes the last bit of blood into the ventricle
  2. Atrial diastole begins
  3. Ventricular systole first phase
    1. contraction force pushes AV valves closed but not enough force to open semilunar valves
  4. Ventricular systole second phase
    1. pressure rises to exceed pressure of the arteries and semilunar valves open and blood is ejected
  5. Ventricular diastole, early
    1. ventricles relax, pressure drops, blood flows back agains semilunar valves, closing them.
    2. blood flows into the relaxed atria
  6. Ventricular diastole, late
    1. all chambers are relaxed, ventricles fill passively
2
Q

What are the three major events of ventricular diastole?

A
  1. Early diastole: pressure dropping and semilunar valves closing. Pressure less than arteries but more than atria.
  2. Late diastole: Pressure drops below atri, AV valve opens. Rapid ventricular filling passively
  3. Atrial systole: atrial contraction tops off the last bit of blood into ventricle
3
Q

What is the approximate End Diastolic Volume?

A

about 120 ml in ventricles

4
Q

What are the two major events of systole?

A
  1. First phase
    1. isovolumetric contraction, pressure increase, valves closed.
    2. pressure rises until ventricular pressure exceeds aortic pressure and valve opens
  2. Second phase
    1. Semilunar valves open
    2. rapid ejection followed by reduced ejection as ventricular pressure falls
5
Q

Normal intracardiac pressures of PA

A

Systolic: 15-30 mmHg

Diastolic: 3-12 mmHg

6
Q

Normal intracardiac pressure RA

A

0-8 mmHg

nickel

7
Q

Normal intracardiac pressures RV

A

Systolic: 15-28 mmHg

End-Diastolic: 0-8 mmHg

Quarter/nickel

8
Q

Normal Intracardiac pressures Aorta

A

Systolic: 96-140 mmHg

Diastolic: 60-90 mmHg

9
Q

Normal intracardiac pressure LA

A

4-12 mmHg

dime

10
Q

Normal intracardiac pressures LV

A

Systole: 90-140 mmHg

Diastole: 4-12 mmHg

1.25/dime

11
Q

Normal intracardiac pressure in Pulmonary Vein

A

about 9 mmHg

dime

12
Q

Heart Sounds

S1

A

“Lubb”

closure of AV valves

13
Q

Heart Sounds

S2

A

“dubb”

closure of semilunar valves

14
Q

Heart Sounds

S3

A

rapid passive filling

*not normally heard in adults; may be heard in small children or endurance athletes

15
Q

Heart Sounds

S4

A

atrial systole

normally not heard in adults

16
Q

Murmur

A

gurgling sound as blood moves through damaged valves

17
Q

bruit

A

abnormal sound as blood runs past and obstruction through arteries

18
Q

Factors that affect cardiac output

A

CO = SV x HR

Heart rate

Stroke volume: Preload, contractility, afterload

19
Q

inotropic

A

related to strength of contraction

20
Q

chronotropic

A

related to speed of contractions

21
Q

How does the Autonomic nervous system alter HR?

A
  • Sympathetic:
    • NE/Epi
    • Beta 1 receptors
    • positive chronotropic effect
  • Parasympathetic:
    • Acetylcholine
    • M2 receptor
    • negative chronotropic effect
22
Q

What are the two main mechanisms for altering stroke volume?

A

Intrinsic regulation

Autonomic regulation

23
Q

Intrinsic regulation of stroke volume

A
  • Frank-Starling law of the heart
    • increased stretch of myocytes increases strength of contraction
    • by more optimally lining up the myosin and actin so more can “grab” hold
    • increased stretch created by increase in venous return and EDV
24
Q

Autonomic regulation of stroke volume

A
  • Contractility
    • increased strength of contraction due to increased amount of cytosolic calcium (primarily SNS)
    • NE increases Ca++
25
Q

positive inotropes

A

increase contractility

epi/NE

26
Q

negative inotropes

A

decrease contractility

drugs: beta blockers, Calcium channel blockers

27
Q

Ejection fraction equation

A

EF = SV/EDV