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Cardiac > Apex- Cardiac A&P > Flashcards

Apex- Cardiac A&P Flashcards

1
Q

Does hypokalemia increase or decrease RMP?

A

Decrease

hyperkalemia increases RMP (just think, physically increases it closer t

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2
Q

Hypocalcemia (increases/decreases) threshold potential

What is TP?

A

decreases

TP = -70mV

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3
Q

T/F: the wave of depolarization throughout the heart is facilitated by t-tubules

A

False - gap junctions

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4
Q

T/F- ventricular myocytes contain more mitochondria than skeletal myocytes

A

True

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5
Q

Which phase of the ventricular action potential is associated with the GREATEST calcium conductance?

1,2,3,4

A

2

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6
Q

What happens during the 5 phases of the myocytes action potential? (0-4)

A
  • Phase 0- Depolarization → Sodium in (+++)
  • Phase 1- Inital repolarization → Cl- in and K+ out (-)
  • Phase 2- Plateau → Calcium in and K+ out
  • Phase 3- Repolarization → K+ out (—)
  • Phase 4- Maintenance of TP → (K+ out & NA/K-ATPase function)
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7
Q

Match with Phase 0, 1, 2, 3, 4

  • ST segment
  • Potaassium Leak
  • Plateau
  • Isoelectric EKG
  • Q wave
  • Final Repolarization
  • Depolarization
  • Potassium Efflux
  • Calcium influx
  • T-Wave
  • Sodium influx
  • Resting phase
A

Phase 0 - Q-Wave, depolarization, NA++ influx
Phase 2 - ST segment, plateau , Ca++ influx
Phase 3- final repolarization , K+ efflux, T-wave
Phase 4 - potassium leak, isoelectric ECG, resting phase

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8
Q

Which current is responsible for sponatenous phase 4 depolarization in the SA node?

A. I-NA
B. I-K
C. I-Ca
D. I-f

A

D (I-funny channels)

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9
Q

How can volitale anesthetics cause a junctional rhythm?

A

By depressing automaticity of the SA node

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10
Q

What are the 3 phases of action potential in the SA and AV node?

A

Phase 4 = Spontaneous depolarization → Na+ in (I-f) then Ca ++ in (T-type)
Phase 0 = Depolarization → CA++ in (L-type)
Phase 3 = Repolarization → K+

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11
Q

Where are action potentials propagated after the SA node (course through the heart)

A

SA node → internodal tracts → AV node → Bundle of His → Left and Right Bundle Branches → Purkinje Fibers

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12
Q

What is the intrinsic firing rate of the SA node vs AV node vs Purkinje fibers?

A

SA node → 70-80
AV node → 40-60
Purkinjes → 15-40

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13
Q

What is the Keith-Flack node and where does it reside?

A

It’s the SA node and it resides in the right atrium

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14
Q

What is the expected o2 delivery of a 70kg adult?

A. 20ml/dL
B. 1000ml/min
C. 250ml/min
D. 15ml/dL

Can you identify the other numbers? They are signify something lol

A

B. 1,000 mL/min

A. 20ml/dL = Arterial o2 content (CaO2)
B. 1,000mL/min = Oxygen delivery (DO2)
C. 250ml/min = O2 consumption (VO2)
D. 15ml/dL = Venous o2 content (CvO2)

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15
Q

How do you calculate o2 delivery (DO2)?

A

CO x CaO2 x 10

CaO2 = O2 bound + O2 dissolved

CaO2 = (Hgb x SaO2 x 1.34) + (PaO2 x 0.003)

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16
Q

The amount of oxygen dissolved in blood (PaO2) follows what law?

A

Henrys

-at a constant temp, the amount of gas that dissolves in a solution is directly proportional to the pressure of that gas

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17
Q

Blood flow is inversely propostional to:
A. Body temp
B. Vessel Diameter
C. Afrteriovenous pressure difference
D. Hematocrit

A

D. Hematocrit

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18
Q

What 3 things does poiseuille’s law consider?

which one impacts blood flow the most?

A

Vessel diameter (R^4)
Viscosity
Tube length

*changing diamater is best way

Doubling radius → flow increase 16 fold ; Tripling radius → increases 81 fold ; Quadrupling → 256 fold

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19
Q

What reynold’s number predicts that flow will be mostly laminar vs mostly turbulant vs transitional?

A

<2,000 = laminar
>4,000 = turbulant
2,000-4,000 = transitional

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20
Q

Why do we combine PRBCs with normal saline anad run it through a warmer? What’s the overall purpose?

A

To improve flow
-adding saline reduces viscosity and improves flow
-warming fluid reduces viscosity and improves flow

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21
Q

2 ways to calculate MAP

A

SBP + (2)DBP / 3

(CO x SVR)/ 80 + CVP

SVR = MAP - CVP/CO * 80

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22
Q

CPP autoregulates between what

A

MAPs between 60-140mmHg

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23
Q

What is PAOP the same as?

A

LVEDP

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24
Q

CPP =

A

DBP- PAOP (or LVEDP)

CPP is the driving force of coronary blood flow

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25
Q

What variables are related by the Frank-Starling mechanism?

A. LVEDP and SVR
B. Contractility and CO
C. PAOP and SV
D. CVP and MAP

A

C. PAOP & SV

remember PAOP = LVEDP = Preload (I think)

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26
Q

What is the functional unit of the contractile tissue in the heart?

A

The sarcomere

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27
Q

True or False: The end diastolic volume is called preload

A

True - the amount of blood in the ventricles just prior to systole

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28
Q

Atrical contraction (kick) contributes what percent to CO?

A

20-30%

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29
Q

Define preload

A

The amountof tension on the ventricle wall at the end of diastole (just prior to systole)

*think of it as a rubber band- - increased stretch/tension = greater snap after tension is released

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30
Q

Conditions associated with decreased myocardial compliance where these people wouldn’t tolerate afib or junctional rhythm as well (4)

A
  1. Myocardial hypertrophy
  2. Diastolic HF (HF with preserved EF) → think can’t relax, less compliant
  3. Fibrosis
  4. Aging
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31
Q

LVEDP, LAP, and PAOP are all surrogate measures of what

A

LVEDV

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32
Q

What is the primary substance that determines inotropy?

A

Calcium

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33
Q

5 ways to increase myocardial contractility

A
  1. SNS stimulation
  2. Catecholamines
  3. Calcium
  4. Digitalis
  5. PDE inhibitors

PDE turns off adenylate cyclase which converts ATP → cAMP; so inhibiting this leads to increased concentrations of cAMP

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34
Q

A reduction of which factor would MOST likely augement stroke volume?
A. Preload
B. Contractility
C. Afterload
D. MAP

A

C. Afterload

*READ - note REDUCTION in which factor

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35
Q

What is afterload and what it is set by?

A

The tension the heart must overcome to eject its stroke volume.

-usually set by SVR (mainly at the arterioles)

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36
Q

Normal SVR

A

800-1500 dynes/sec/cm

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37
Q

What 2 major things can reduce afterload

A
  1. Arterial vasodilators → Propofol, Clevidipine
  2. Sympathectomy → Regional anesthesia
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38
Q

Which phases of the cardiac cycle are associated with an open mitral valve and closed aortic valve? (Select 3)

-Isovolumetric contraction
-Rapid ventricular filling
-Ventricular ejection
-Atrial systole
-Diastasis
-Isovolumetric relaxation

A

Rapid ventricular filling
Atrial systole
Diastasis (middle 3rd of diastole)

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39
Q

What is the incisura

A

The dicrotic notch

The onset of AV closure causes a short period of retrograde flow from the aorta towards the aortic valve, followed by termination of retrograde flow upon complete AV closure.

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40
Q

What does the height of a PV loop signify?

What about the width?

A

Ventricular pressure

Width = ventricular volume

41
Q

Describe valve positions of the PV loop - bottom/top/left/right corners

A

Bottom left = MV opens
Bottom right = MV closes
Top right = AV opens
Top left = AV closes

42
Q

Label

A
43
Q

EF values for normal, mild, mod, and severe dysfunction

A

Normal = >/= 50%
Severe = </= 25%

Mild dysfunction = 41-49%
Moderate dysfunction = 26-40%

44
Q
A

IV fluid bolus

increased preload → increased EDV → increased force of contraction; *note loop gets wider but returns to orginal ESV

45
Q

what would cause a PV loop to get wider but still return to starting ESV?

A

increased preload

46
Q

What would cause a PV loop to get narrower but still return to the orginal ESV?

A

Decreased preload

47
Q

What would cause a PV loop to get wider, taller, and shift to the left?

A

increased contractility

48
Q

What would cause a PV loop to get narrow, shorter, and shift to the right?

A

Decreased contractility

49
Q

What would cause the PV loop to get narrower, taller, and shift the ESV to the right

A

Increased afterload (cant fully empty so increased ESV)

50
Q

What would cause the PV loop to get wider, shorter, and shift the ESV to the left?

A

decreased afterload (can fully empty)

51
Q

Which coronary artery supplies this area

A

Circumflex- supplies left lateral wall of Lv

LAD- supplies anterior wall of LV, 2/3 septum and small portion of the anterior RV
RCA- supplies posterior wall of the LV, most of the RV, and posterior 3rd of the septum

52
Q

Which coronary arteries arise from the aortic root?

A

Left and Right (LCA & RCA)

53
Q

What does the LCA divide into?

A

the LAD and circumflex arteries

54
Q

Where does the coronary sinus reside? What does it do?

A

on the hearts posterior surface

-it returns cardiac venous blood to the right atrium
* it can be cannulated to administer retrograde cardioplegia solution during CPB

55
Q

When using TEE/TTE, the best view fro diagnosing myocardial ischemia is what?

A

Midpapillary muscle level in short-axis

56
Q

What does the LAD perfuse

EKG leads

A

LV - anterolateral and apical walls
Anterior 2/3 of intraventric septum

V1-V4

57
Q

What does the circumflex artery supply?

EKG leads

A

Left atrium
LV - lateral posterior walls

I, avL, V5-V6

58
Q

What does the RCA perfuse?

EKG leads

A

Right Atrium
Right Ventricle
Posterior LV
Interarterial septum
Posterior 3rd of the interventricular septum

II, III, aVF

59
Q

Which coronary artery determines coronary dominance?

A

Posterior descending artery

60
Q

In 70-80% of patients, the ________ gives rise to the PDA, and we call this (left/right) dominance .

A

RCA (70-80%)
*Right side dominance

in the reminder of patients, the circ or RCA + circ supply the PDA and we call it LEFT dominance or co-dominance

61
Q

The SA node receives its blood supply from the ____ in 70% of patients

what about the remainder of the population?

A

RCA

circumflex in the rest

62
Q

The AV node recieves is blood supply from the ______ in 80% of patients

A

RCA

63
Q

What supplies blood to the bundle of his and left and right bundle brances?

A

LCA

64
Q

Most cardiac blood returns to which cardiac vein?

A

Coronary sinus

65
Q

Match: Great, middle, and anterior cardiac veins with :

RCA, LAD, PDA

A

Great = LAD
Middle = PDA
Anterior = RCA

66
Q

A small amount of blood empties directly into all 4 chambers via the __________ veins

A

Thebesian veins - contributes to a small amount of anatomic shunt

67
Q

Label

A

orange supplied by RCA
blue supplied by circ
green supplied by LAD

68
Q

II, III, aVF - what leads/ what CA

A

Inferior/RCA

69
Q

What are the lateral leads and what supplies them?

A

I, aVL, V5, V6
Circ

70
Q

What are the septal leads and what supplies them?

A

V1-V4
LAD

71
Q

Mediators of coronary vasodilation include (select 2)
- adenosine
- beta 2 stimulation
- alpha 1 stimulation
- hypocapnia

A

Adenosine & beta 2 stimulation

*Alpha-1 and hypocapnia cause coronary vasoconstriction

72
Q

Coronary blood flow at rest

what % of CO

A

225-250ml/min

~ 5%

73
Q

Coronary Blood flow =

A

Coronary perfusion pressure/coronary vascular resistance

74
Q

Coronary Perfusion Pressure =

A

Aortic DBP - LVEDP

75
Q

Coronary blood flow autoregulates between a MAP of what?

A

60-140mmHg

76
Q

What is the most important determinant of coronary vessel diameter?

A

local metabolism

77
Q

At rest, the myocardium consumes o2 at a rate of ______ml/min/100g with an extraction ratio of _____%

A

8-10ml/min/100g
70% extraction ratio

78
Q

What is a byproduct of ATP metabolism and is a potent coronary vasodilator?

A

Adensoine

79
Q

Causes coronary artery constriction or dilation:
Histamine 1
Histamine 2
Alpha
Beta 2
Muscarinic

& How

A

Histamine 1→ CX (^ intracellular CA)
Histamine 2→ dilate (^cAMP, decreased MLCK sensitivity to CA++)
(histamine- think first is worst, second is the best)
Alpha→ CX (^ intracellular calcium_
Beta 2→ dilate (^cAMP, decreased MLCK sensitivity to CA++)
Muscarinic → dilate (increase nitric oxide)

80
Q

T/F- the RV subendocardium is most vulnerable to ischemia

Why or why not?

A

False - the LV subendocardium is most vulnerable to ischemia bc LV contraction compression the endocardial vessels during systole

flow through the RV is relatively constant throughout the cardiac cycle

81
Q

Which region on the heart does thsi pressure waveform represent?

A

LCA
*flow greatly decreases during ventricular systole due to the mass of hte LV, contraction dramatically compresses the endocardial vessels decreasing flow during systole

82
Q

Which condition increases myocardial o2 consumption?
-decreased diastolic filling time
-decreased end-diastolic volume
-decreased P50
-decreased aortic diastolic BP

A

Decrased diastolic filling time

(another way of saying increased HR)

decreased end-diastolic volume reduces wall stress and reduces demand; deceased P50 shifts the curve to the left (left = love) , less o2 is released to myocardium which decreases supply; decreased aortic DBP reduces coronary perfusion pressure which reduces o2 supply

83
Q

Which condition increases myocardial o2 consumption?
-decreased diastolic filling time
-decreased end-diastolic volume
-decreased P50
-decreased aortic diastolic BP

A

Decrased diastolic filling time

(another way of saying increased HR)

decreased end-diastolic volume reduces wall stress and reduces demand; deceased P50 shifts the curve to the left (left = love) , less o2 is released to myocardium which decreases supply; decreased aortic DBP reduces coronary perfusion pressure which reduces o2 supply

84
Q

Why is tachycardia detrimental to the iscemic heart?

A

Bc it s imultaneously decreases O2 supply while increasing o2 demand

85
Q

If an increased afterload increases myocardial o2 demand, why is it mostly benificial?

A

Bc an increased afterload increases coronary perfusion pressure and typically outweighs the risk of increased wall tension

86
Q

Most perioperative MIs occur when?

A

24-48hrs following surgery

87
Q

What is it that actually causes chest pain?

A

lactic acid production due to anaerobic metabolism

88
Q

How does tachycardia decrease o2 supply?

A

bc the LV is best perfused during diastole, and tachycardia = less time in diastole → less time to deliver o2 to the LV

89
Q

Why shouldnt you increase preload in the cardiac ischemic patient?

A

increased preload increases wall stress, increased wall stress = increased o2 demand

also, increased EDV decreases CPP ( aortic DBP - increased LVEDP = decreased CPP)

90
Q

T/F- inhaled nitric oxide causes hypotension

A

False- it reduces pulm vascular resistance and RV afterload but is inactivated by hemoglobin , explaining it’s ultra-short half-life (~5 secs)

inactivated before it enters systemic circulation

91
Q

T/F- inhaled nitric oxide causes hypotension

A

False- it reduces pulm vascular resistance and RV afterload but is inactivated by hemoglobin , explaining it’s ultra-short half-life (~5 secs)

inactivated before it enters systemic circulation

92
Q

Bradycardia is caused by:
A. making the RMP more positive
B. increasing the slope of phase 4 depolarization
C. Increasing potassium conductance
D. Making the threshold more negative

A

C. Increasing potassium conductance

PNS stimulation increases K+ conductance; since more K (a positive ion) exits the myocite, its interior becomes more negative. This increases the distance b/t RMP and TP – so it takes longer fro the cell to reach TP; slowing the heart rate

93
Q

What 3 things cause the SA node to increase it’s firing rate?

A
  1. The slope of spontaneous phase 4 depolarization INCREASES
  2. TP becomes more negative (shorter distance between RMP and TP)
  3. RMP becomes more positive (shorter distance between RMP and TP)
94
Q

Which phase exhibits greatest conductance of which ion conductance? 0-3

A

Phase 0 = Na+
Phase 1 = Cl-
Phase 2 = Ca++
Phase 3 = K+

95
Q

T/F - contractility is depdendent on neither preload or afterload

A

True!

-contractility is the ability of the sarcomeres to shorten and perform work indpendent of preload and afterload

*remember- Chemicals affect Contractility - especially Calcium

96
Q

What is the MOST potent local vasodilator substance released by the cardiac myocytes?

A. Nitric Oxide
B. Carbon Dioxide
C. Adenosine
D. Prostacyclin

A

C. Adenosine

97
Q
A
98
Q

The Sarcoplasmic reticulum releases calcium when:
A. calcium stimulates the ryanodine receptor
B. Repolarization occurs
C. Troponin binds to the actin/myosin complex
D. The SERCA2 pump is turned on

A

A. Calcium stimulates the ryanodine receptor

-after this, CA binds to TNC on the actin/myosin complex which causes muscle contraction

99
Q

Transection of the right vagus nerve would MOST likely affect:
A. SA node automaticity
B. AV node conduction
C. Bundle of His

A

A. SA node automaticity

the LEFT vagus nerve innervates the AV node

Cardiac (7 decks)

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