Cardiovascular Drugs Flashcards
What are the 2 Classes of Inotropes
- Receptor Dependent
2. Phosphodiesterase inhibitors
Normal Myocardial Cell
In the body we have circulating hormones ex:(norepi &epi) these hormones stimulate Beta 1 receptors-contribute to production of Adenyl Cyclase-combines with ATP (fuel for the cell)-to produc cAMP (2nd messenger system within the cell, helps facilitate movement of CA into the cell.
- Receptor Dependent Inotrope?
Stimulates the Beta 1 receptor sites on the cell. Ex: Dobutamine
Down Regulation of the Beta 1 Receptors
Some patients that are in shock have high levels of norepi & epi circulating and the Beta 1 receptors get overloaded. So CO & CI drop and they are started on Dobutamine. This could create Down Regulation of the Beta 1 receptors. (ask for Milronine )
- Phosphodiesterase Inhibitor
Shuts down the phosphodiesterase as a result we have more cyclic AMP availabel and more CA goes into the cell causing an increase in CO and CI.
*Milronine has nothing to do with the beta 1 receptors
Where are Beta 1 receptors found:
Primarily in the heart
What does Beta 1 stimulation produce?
- increase in HR (+chronotropic effect)
- increase in contractility (+Inotropic effect)
- increase conduction velocity through AV node (+Dromotropic effect)
Where are Beta 2 receptors found?
Found in the lungs and peripheral arterioles
What does Beta 2 stimulation Produce?
- Relaxation of smooth muscle
- Vasodilation (peripheral)
- Bronchodilation
Where are Alpha 1 receptors found?
Lungs and peripheral arterioles
What does stimulation of Alpha 1 receptors produce?
*constriction of smooth muscle (vasoconstriction)
*
Where are Dopaminergic Receptors found ?
Renal, mesenteric vascular beds
What does stimulation of the dopaminergic receptors produce?
*Vasodilation
Dopamine
- Is an immediate precursor of norepinephrine
- Neurotransmitter in central and peripheral nervous system
Effects of Dopamine?
- Decrease aldosterone secretion in adreanal cortex. (less Na & H2O reabsorption so UO will
increase) - Inhibits thyroid stimulating hormone and prolactin release. (can produce hyper or hypothyrodism)
- Inhibits insulin secretion
Dopamine Range
2-10mcg/kg/min = increase contractility (beta effect) >10mcg/kg/min = vasoconstriction (Alpha effects)
Dopamine Indications?
- Shock state
- Cardiogenic
- Septic
- Post Cardiac Surgery
Dopamine Side Effects?
- N/V
- Tachyarrhythmias
- Supraventricular and ventricular
- Profound vasoconstriction
Dobutamine
- Synthetic Catecholamine directly stimulates
- Beta 1 receptors- increasing myocardial contractility that will increase HR
- Beta 2 Vasodilation
- Alpha 1 vasoconstriction
- Inotropic effect
- May drop MAP slightly
Dobutamine Indications?
- CHF
- Shock States
- Septic
- Stress testing
Dobutamine side effects?
- increase HR
- Dysrhythmias, ventricular & supraventricular
Dobutamine dosage
- 5-20mcg/kg/min
* **Never administer in an alkaline solution such as sodium bicarbonate.
Epinephrine Cardiac Effects
- Has dose dependent effects*
- Mediated through Beta receptors.
0. 005-0.02 mcg/kg/min = increase HR, +Inotropic effects; vasodilation (decrease SVR)
Epinephrine Vascular Effects
Mediated through alpha receptors at high doses: increase SVR; increase BP, renal artery vasoconstriction
Epinephrine Beta 2 stimulation
Bronchodilation
Epinephrine Alpha effects
With higher infusion rates = 1mg IVP (ACLS situation) short 1/2 life 2 min
Epinephrine Indications?
- Lower output state
- Cardiac Arrest
- Shock States
- Asthma
- Anaphylaxis
Epinephrine Side Effects?
- Restlessness, fear
- Tachyarrhythmias
- Severe HTN
- Cardiovascular Accident
- Hypokalemia
- Hypophosphotemia
Norepinephrine
Low Doses - Beta Stimulation
High Doses - Alpha stimulation
Norepinephrine Dosage?
Start 0.5-0.10mcg/kg/min or 2-4mcg/min and titrate up