1D4 Flashcards
1
Q
what is cardiac output
A
the amount of blood ejected from the heart in liters/min
2
Q
what is the normal cardiac output
A
4-8 L/min
3
Q
what are the determinants of cardiac output
A
- heart rate
2. stroke volume
4
Q
what are the determinants of stroke volume
A
a. preload
b. afterload
c. contractility
5
Q
what is the equation for cardiac output
A
CO = HR x SV
6
Q
what is the cardiac index
A
a more accurate determinant of heart function
7
Q
what does cardiac index take into account
A
the pt’s body surface area (m^2)
8
Q
what is CI determined by
A
HR, SV, height, weight
9
Q
what is HR
A
of beats per minte
10
Q
what does optimal heart rate balance
A
coronary blood flow with cardiac output
11
Q
when does coronary blood flow take place
A
mainly during diastole
12
Q
what is the optimal heart rate b/m
A
80-100
13
Q
normal sinus rhythm ensures ______ ______ and maximizes _____ ______
A
ensures atrioventricular synchrony and maximizes cardiac efficiency
14
Q
what is stroke volume
A
the amount of blood which is ejected from the heart with each beat
15
Q
what can stroke volume be manipulated by
A
fluids, inotropes, vasopressors and vasodilators
16
Q
what is preload
A
pressure or stretch exerted on the walls of the ventricle by blood filling at end diastole
17
Q
what is the saying for Starling’s law of the heart
A
“the heart will pump what it receives”
18
Q
the frank starling mechanism describes the ability fo the heart to change its force of _____ (and hence ___ ____) in response to changes in ____ ____
A
its force of contractility (and hence stroke volume) in response to changes in venous return
19
Q
if the end diastolic volume increases, there is a corresponding _____ in stroke volume
A
increase
20
Q
preload reflects
A
volume status
21
Q
preload increases with
A
hypervolemia
22
Q
preload decreases with
A
hypovolemia
may result from bleeding, fluid loss, or vasodilation
23
Q
what is afterload
A
resistance to left ventricular contraction
end systolic wall stress or resistance
24
Q
how is after load assessed
A
by measuring systemic vascular resistance (SVR)
25
after load is the degree of ____ or _____ of the arterial circulation
constriction or dilatation
26
high after load increases what and decreases what
increases myocardial work and oxygen demand
| decreases cardiac output
27
after load increases with (5)
- hypothermia
- aortic valve stenosis
- history of hypertension
- increase in SVR
- vasoconstriction
28
contractility
the ability of the myocardial muscle fiber to shorten independent of preload and afterload
29
Contractility is the ability of the heart to ____ and the ____ at which it does so
heart to contract and the force at which it does so
30
force of contraction is determined by
the concentration of calcium ions in the cell
31
increase contractility can be increase by
flooding cell with more calcium (beta agonist) or by keeping more calcium in the cell and not letting it escape
32
when do you give calcium
after cross clamp
33
myocardial contractility is enhanced by using what
isotrope pharacological agents such as adrenaline, dobutamine, milronone and levosimendan
34
the central nervous system consists of the
brain and spinal cord
35
the central nervous system is responsible for
processing and interpreting information
36
the peripheral nervous system includes
all of the nervous tissue outside of the brain and spinal cord
37
what is the PNS comprised of what nervous systems
the autonomic nervous system and the somatic nervous system
38
what is the ANS
motor system that receives and conducts information from the brain and spinal cord to the effector cells
39
the ANS can be further divided into the
sympathetic and parasympathetic divisions
40
SNS is stimulated by what and where
acetylcholine at the preganglionic site
&
norepinephrine at the postganglionic site
41
the receptors of the SNS are also called ____ receptors
adrenergic
42
what are the 3 main adrenergic receptors
alpha
beta
dopaminergic
43
what is acetylcholine
the neurotransmitter at both pre and post sites in the PNS
44
PNS receptors are refereed to as _____ receptors
cholinergic receptors
45
what are the two major types of cholinergic receptors
nicotinic and muscarinic
46
where are nicotinic receptors found
at neuromuscular junctions
47
where are muscarinic receptors found
throughout the body on many target tissues
48
what are the two type of alpha receptors
Alpha 1
| Alpha 2
49
which alpha receptor is a postsynaptic receptor that elicits peripheral vasoconstriction
Alpha 1
50
which alpha receptor is a presynaptic receptor that decreases the release of NE at sympathetic nerve terminals
Alpha 2
51
alpha 1 location and actions
location: vascular smooth muscle
action: vasoconstriction
52
alpha 2 location and actions
location: presynaptic neurons
action: decrease NA release, decrease Act release, decrease insulin release
53
what are the the three subtypes of beta receptors
beta1
beta 2
beta 3
54
what are beta one receptors
postsynaptic receptors that when activated INCREASE HR and contractility, increase AV node conduction, and increase renin release
55
what are beta 2 receptors
postsynaptic receptors cause vasodilation, insulin release, bronchodilator, and glycogenolysis
56
what is beta 3 receptors
postsynaptic receptors cause increased lipolysis
57
B1 location and actions
location: heart
actions: increase rate, force, and automaticity
58
B2 location and actions
location: smooth muscle
action: relaxation
59
B3 location and actions
location: adipose tissue
action: increase lipolysis
60
what are the two subtypes of dopaminergic receptors
dopamine 1
| dopamine 2
61
what is dopaminergic 1 receptors
postsynaptic receptors that cause renal and mesenteric vasodilation
62
what is dopaminergic 2 receptors
presynaptic receptors that inhibit NE release
63
what receptors act on brain Parkinson's disease, schizophrenia
D2
64
what part of the cardiopulmonary system express D1, D2, D4 receptors?
the pulmonary artery
65
what effect does D1, D2, and D4 receptors have on the pulmonary artery?
cause vasodilatory effects of dopamine in the blood vessels
66
what dopamine receptors does the heart have and what does it do
D4
increase CO and increase contractility without increasing HR
67
what dopamine receptors does the kidney have and what does it do
D1
affects diuresis and natriuresis
68
what are the mechanisms that regulate CO
ANS
PNS
SNS
69
how does the autonomic nervous system regulate cardiac output
alter the HR, contractility, preload and afterload
70
how does the parasympathetic nervous system regulate cardiac output
by slowing down the HR
-operates to conserve the energy expenditure of the body
71
how does the sympathetic nervous system regulate the cardiac output
innervates the conduction system of the heart, the arterioles, and veins
-regulates energy expenditure and is operative during stressful situations
72
what does stimulation of the SNS produce
an increase in HR, contractility, preload (venous constriction) and after load (arterial vasoconstriction)
73
what are inotropes
medicines that change the force of your heart's contractions
74
what is the main goal of inotropic drug therapy
to improve myocardial function and end-organ perfusion
75
how do you increase CO
by increasing stroke volume and/or heart rate
76
what does increasing diastolic pressure increase
MAP
77
what are the two kind of inotropes
positive inotropes
| negative inotropes
78
what do positive inotropes strengthen and help
strengthen the force of the heartbeat and help the heart pump more blood with fewer heartbeats
-for congestive heart failure or cardiomyopathy
79
what do negative inotropes weaken and help
weaken the force of the heartbeat
-include beta-blockers, calcium channel blockers, anti arrhythmic medicines
80
what do negative inotropes treat
treat hypertension, chronic heart failure, arrhythmias, and angina
81
all positive inotropic drugs work by
increasing calcium entry into the myocyte increasing the physiologic response of "calcium induced - calcium release"
82
when the increase of "calcium induced - calcium release", what is the result?
increase of the number of cross bridges that can form thus increasing contraction
83
in diastolic dysfunction, there may be an increase and decrease in what, and it leads to what?
increase in sarcomere Ca2+ sensitivity and a decrease in the rate of Ca2+ reuptake via SERCA2a and NCX
leads to state of Ca2+ overload
84
in diastolic dysfunction, the state of Ca2+ overload leads to and what does it cause?
a slow or incomplete relaxation of the ventricles and causes pulmonary edema and hypertension
85
what happens when augmenting diastolic function
- inotropes increase filling time
- lower LVEDP
- decrease. LA pressure
- decrease oxygen demand
86
which vasopressors-inotropes are given after lung transplant
Beta2: bronchial dilation and vasodilation of coronary arteries
87
what are sympathomimetics
substances that mimic or modify the actions of endogenous catecholamines (NE, E, dopamine) of the SNS
88
direct agonists directly activate
adrenergic receptors
89
indirect agonists enhance the
actions of endogenous catecholamines
90
what is epinephrine (adrenaline) considered
both a hormone and medication
91
where does Epinephrine act?
Direct acting catecholamine agonist at alpha1, alpha2, beta1, beta2 receptors
92
what kind of response is called from epinephrine dose?
"balanced response"
93
response at various receptors is
dose dependent
94
what are the advantages of Epinephrine? (4)
1. direct acting response not dependent on NE stores
2. balanced alpha and beta response
3. effective bronchodilator
4. Systole is shortened allowing for increased diastolic filling as long as no tachycardia
95
what are the disadvantages of epinephrine?
dose dependent
1. potential for tachycardia
2. increased oxygen demand
3. PVR may increase in higher doses potentiating RV failure
96
Norepinephrine directly acts on
alpha, apha2, and beta1 agonist
97
what does norepinephrine not act on
beta2
98
actions of norepinephrine
```
increase contractility (minimal)
increases CO (may decrease due to SVR)
increase BP
increase SVR
increase PVR
```
99
advantages of norepinephrine
very effective alpha1 effect
may be effective when phenylephrine is not due to increased potency
100
disadvantages of norepinephrine
- reduced end organ perfusion
- risk of ischemic bowel
- increase PVR
101
what is dopamine
catecholamine precursor to NE and E that has both direct and indirect actions that are dose dependent
102
direct actions of dopamine
alpha1
beta1
beta2
D1 agonist
103
indirect actions of dopamine
increase endogenous NE
| does dependent
104
what is dopamine metabolized by
MAO and COMT
105
advantages of dopamine
increased renal flow
| easy to titrate response
106
at low doses, what is dopamine useful as
vasodilator
107
how much is a "renal dose" of dopamine
1-3 ug/kg/min
| -works primarily at D1 receptors to increase renal and mesenteric flow
108
at 3-10 ug/kg/min, where does dopamine work
at beta1 and beta2
| increased HR and CO , decreased SVR
109
at > 10 ug/kg/min, where does dopamine work and what does it do
alpha1 starts to dominate response
- increased SVR and SVR
- decreased renal flow
- increased in HR
110
what is a disadvantage of dopamine
an increase in after load may decrease CO and increase oxygen demand
111
where does dobutamine directly act
beta1 synthetic agonist with little alpha1 and beta2 effects
112
what does dobutamine increase
HR
CO
contractility
113
what does dobutamine decrease
LVEDP
SVR slightly
PVR (beta2)
114
advantages of dobutamine
decreases after load while increasing contractility, therefore decreasing how hard heart has to work
no MAO metabolism, COMT only
115
what are the disadvantages of dobutamine
1. tachycardia
| 2. non-selective vasodilator which may increase shunting
116
what is ephedrine
plant derived non-catecholamine with mild direct beta1 and beta2 effects
117
ephedrine is primarily an _____ effect via ___ release
an indirect effect via NE release
118
is ephedrine metabolized by MAO or COMT
no
119
length of action of ephedrine
5-10 min
120
what are the physiological effects of ephedrine
-increased HR slightly, CO, contractility, BP, SVR slightly, preload increased (vasoconstriction)
121
what is the dose of ephedrine
5-10 mg bolus IV
max dose: 60 mg
122
advantages of ephedrine
1. short duration of action
| 2. not likely to cause tachycardia
123
ephedrine is used in pregnancy. why
does not reduce placental blood flow because it doesn't cross placenta
safe to give
124
disadvantages of ephedrine
- little or no effect if NE stores are depleted
| - MAo inhibitors indirectly effect ephedrine
125
what is phenyephrine
direct acting on alpha1
| non-catecholamine
126
what are the beta effects on phenylephrine
none
127
actions of phenylephrine
decrease HR
increase BP
increase SVR
increase coronary perfusion pressure w/o increase MVO2
128
what is a bad action of phenyelphrine
increase PVR
129
how long and what dose of phenyelphrine
<5 minutes
IV infusion = 100-500 ug/min
bolus 50-200 ug (on CPB usually 100 ug)
130
what is methoxamine
synthetic non-cathecholamine
131
what does methoxamine directly affect
direct alpha1 agonist
132
actions of methoxamine
increase systolic and increase diastolic BP
increase SVR
decrease HR
133
what is the difference between methoxamine and phenyelphrine
methoxamine has a long duration of action
134
on CPB, you give 1 cc bolus of what
methoxamine
135
1 cc bolus =
100 mcg/ml
136
what does phosphodiesterase inhibitors do
prevents breakdown of cAMP by enzyme phosphodiesterase
137
causes of phosphodiesterase inhibitors
increase in intracellular Ca+ in myocytes
augments catecholamines at B1 B2 receptors
138
actions of phosphodiesterase inhibitors
- inodilation: Increase rate and increase force of contraction
- peripheral vasodilation in skeletal muscle (B1)
- bronchodilation (B2)
139
indications of PDE3
- aminophylline: asthma, cardiac failure
- enoximone: cardiac surgery, pt failing to respond to dobutamine
- inocor
- primacor
140
what is the most common vasopressor
milrinone
141
what is milrinone
PDE III inhibitor
142
what does milrinone inhibit
cAMP breakdown
143
actions of milrinone
increase CO
decrease SVR and decrease PVR
decrease Preload
144
onset and offset of milrinone
max effect within 15-20 min
half life varies b/w 30-60 min
145
advantages of milrinone
- more dependable in states where receptors may be compromised like CHF
- improves RV function due to PVR effects
146
disadvantages of milrinone
vasodilation with loading dose (20-50 ug/kg over 10 min)
147
what are the cardiac glycosides (digitalis)
digoxin
| digitoxin
148
what are the actions of cardiac glycosides
increase force and increase rate of contractions by action on the cellular sodium potassium ATPase pump
-increase inotropy
increase ejection fraction
decrease preload
decrease pulmonary congestion/edema
149
what is cardiac glycosides used for
1. low output heart failure - CHF
2. atrial fibrillation and flutter
3. paroxysmal atrial tachycardia
150
what is digitalis toxicity
occurs with plasma concentration >2.0 ng/ml
-can cause life-threatening arrhythmias
