Positive Inotropes And Vasopressors Flashcards
Beta 1 receptors do what?
- increase HR and contractility
- release renin (increase sodium and water rentention)
Peripheral resistance myocardial fiber contraction at the start of systole
After load
Mechanism for Milrinone:
- Decrease breakdown of cAMP
- PKA phosphorylates Ca++ channels
- Increase Ca++
- Increase in force of cardiac muscle contraction
How does a moderate dose of dopamine increase CO?
- Act on Beta1 receptors
- Increase cAMP
- Increase intracellular Ca++
- Increase force of cardiac contraction
- Increase contractility and HR
- Increase CO
What lowers after load?
Arterial vasodilation
Filled volume of ventricle prior to contraction
EDV
Frank-Starling mechanism is the relationship between what?
Preload and cardiac performance
amount of blood that returns to the heart
Preload
Alpha 2 receptors do what?
NE binds to alpha 2 receptors on pre-synaptic neuron
What is contractility reasonably reflected by?
Ejection fraction (EF)
What does low dose (<3mcg/kg/min) of dopamine do?
- vasodilation (increase renal blood flow)
- increase natriuresis (elimination of Na+ in body=decrease water in body)
How does a high dose of dopamine increase BP?
- Acts on Alpha1 receptors
- Increase vascular intracellular Ca++
- Vasoconstriction
- Increase SVR
- Increase BP
Equation for EF
Amount of blood pumped out of the ventricle / total amount of blood in ventricle
What do phosphodiesterases do?
Breaks down cAMP
Where do you see diastolic dysfunction?
Heart failure with preserved EF
How can EF be assessed non invasively?
Echocardiography
Where is systolic dysfunction seen?
Heart failure with reduced EF
What is CO?
Volume blood / minute (HRXSV)
Alpha 1 receptors do what?
- contract walls of blood vessels
- mydriasis (pupil dilation)
- urinary retention
3 positive inotropes?
Dobutamine
Dopamine
Milrinone
Dobutamine reflects with Beta 1:
- increase HR and contractility
- increase O2 and energy demands
Effects of phenylephrine:
Increase SVR (minimal effect on HR or contractility)
NE attachment?
Potent Alpha1 receptor agonist
Modest Beta stimulation (B1>B2)
Impaired ventricular filling
Diastolic dysfunction
Voluntary movement of our skeletal muscles
Somatic nervous system
NE effect with Alpha 1 mechanism:
- Vasoconstriction
- Increase SVR
- Increase BP
NE effect with Beta:
- moderate increase CO
- HR remains unchanged
What receptors do Phenylephrine attach to?
ONLY Alpha1 agonist
What receptors do dobutamine go for?
Beta agonists
-highly selective for Beta1 and some Beta2
What receptors do Epi effect?
Balanced Beta1, Beta2, and Alpha1 adrenergic agonist
What does moderate dose (4-10mcg/kg/min) of dopamine do?
Increase CO
What are inotropes?
Beta agonists (increase contractility)
What is milrinone?
Phosphodiesterase inhibitor
Therapeutic uses for Phenylephrine (2):
- vasodilatory hypotension (with decrease SVR)
- vagal-mediated and medication-induced hypotension
What is Digoxin used for?
Decrease HR
Therapeutic uses of dopamine (4):
- severe hypotension
- acute heart failure
- shock (vasodilator, cardiogenic)
- sever bradycardia
What are vasopressors?
Alpha 1 agonists (increase SVR, vasoconstriction)
Impaired ventricular emptying, loss of contractile strength
Systolic dysfunction
What is SV determined by? (3)
- preload
- after load
- strength of contraction
Percentage of end-diastolic volume ejected with each contraction
EF
Does NE or dopamine have a greater dysrhythmia effect?
Dopamine
What is the mechanism for Dobutamine (beta1)?
- Attaches to beta1
- Adenylate cyclase convert ATP to cAMP
- PKA phosphorylates Ca++ channels
- Increase Ca++ = increase force of cardiac muscle contraction
Therapeutic uses for Epi (4):
- cardiopulmonary resuscitation for cardiac arrest
- shock (cardiogenic, vasodilator)
- bronchospasm/anaphylaxis
- symptomatic bradycardia
Adverse effects of phenylephrine (4):
- reflex bradycardia
- ischemia of digits and various organ systems
- tissue necrosis with extravasation
- severe HTN
What are the vasopressors?
NE
Epi
Phenylephrine
What does a high dose (>10mcg/kg/min) of dopamine do?
Increase BP
Toxicity of Digoxin:
- GI upset, altered color perception, malaise
- bradycardia, AV block, ventricular tachycardia
What is “inodilator”?
Milrinone that causes increase in cardiac contraction and smooth muscle vasodilation
When is milrinone not used when considering SBP?
<90mmhg
Adverse effect of NE (2):
- dysrhythmias
- ischemia of digits and various organ systems
If there’s increased preload, what happens to SV?
Increase
Residual volume of blood remaining in the ventricle after ejection
ESV
What is the mechanism for Dobutamine (beta2)?
- Attach to Beta 2
2. Causes vasodilation and lowers PVR
Adverse effect of dopamine (4):
- tachycardia
- atrial and ventricular dysrhythmias
- nausea and vomiting
- ischemia of digits and various organ systems
When should milrinone NOT be used?
Chronic heart failure
Cause increase morbidity and mortality
What are the side effects for dobutamine?
Tachycardia
Palpitations
Arrhythmias
In LV dysfunction: as SVR goes down, what does SV do?
Goes up
What does increase in cAMP in smooth muscle cause?
Relaxation, vasodilation
What is SV?
Volume blood / beat
What is the treatment for milrinone used for?
Acute heart failure
Involuntary movement of the smooth muscles and glands of our organs
Sympathetic and parasympathetic
Autonomic nervous system
Beta 2 receptors do what? (6)
- dilate smooth muscle cells
- bronchodilation
- decrease motility
- secretion of aqueous humor
- more glucose
- release of glucagon
Effects of Epi:
Increase contractility
Increase HR
Increase SVR
Increase BP by contracting blood vessels
Vasopressors
Increase strength of heart muscle contraction
Positive inotropes
Dobutamine effects of beta 2:
- stimulate heart (acute heart failure or cardiogenic shock)
- not appropriate for chronic heart failure (tolerance)
Adverse effects of Epi (4):
- dysrhythmias
- ischemia of digits and various organ systems
- high and prolonged doses can cause direct cardiac toxicity
- severe HTN (cerebral hemorrhage)
What is ventricular SV?
Ventricular end-diastolic volume - end-systolic volume
What neurons are responsible for sympathetic nervous system?
Postganglionic neurons (adrenergic neurons)
Side effects for milrinone:
- arrhythmia
- hypotension (due to vasodilation)
Indication for Digoxin:
- atrial flutter (control ventricular rate)
- HR with reduced EF
What does Digoxin do?
Inhibit ATPase
- increase Na+
- Increase Ca++
Therapeutic uses for NE (2):
- hypotension
- shock-like state accompanied by peripheral vasodilation