Positive Inotropes and Vasopressors

Question 1

Positive inotrope

Answer 1

increases strength of heart muscle contraction

Question 2

Vasopressors

Answer 2

increase blood pressure by contracting blood vessels

Question 3

Beta 1 receptors

Answer 3

1.) increase HR and contractility
2.) release renin for the RAAS system and increase sodium and water retention

Question 4

Beta 2 receptors

Answer 4

Dilate smooth muscle cells, bronchodilation, decrease gut motility, secrete aqueous humor, increase glucose, and release glucagon

Question 5

Alpha 1 receptors

Answer 5

Constrict the walls of blood vessels, cause pupil dilation (mydriasis), and urinary retention

Question 6

Alpha 2 receptors

Answer 6

Negative feedback loop which limits pre-synaptic NT release

Question 7

Ejection fraction

Answer 7

percentage of end-diastolic volume ejected with each contraction (SV/end diastolic volume)

Question 8

Afterload

Answer 8

the force resisting myocardial fiber contraction at the start of systole. Arterial vasodilation lowers after load

Question 9

Frank starling mechanism of the heart

Answer 9

If venous return is increased, the ventricular end diastolic pressure and volume of the ventricle are increased, which stretches the sarcomeres (increases preload) this increased SV because of increased contraction

Question 10

Diastolic disfunction

Answer 10

Impaired ventricular filling. Primary abnormality in HF with preserved ejection fraction. Lower EDV = lower CO (hypertrophy heart)

Question 11

Systolic disfunction

Answer 11

impaired ventricular emptying, loss of contractile strength. Abnormality seen in HF with reduced EF. Increased ESV = decreased CO

Question 12

Inotropes

Answer 12

Beta agonists which increased contractility

Question 13

Vasopressors

Answer 13

Alpha 1 agonists which increase SVR

Question 14

Dobutamine

Answer 14

Beta agonist. Highly selective for Beta 1. Increased cAMP –> increased PKA –> Increase Ca2+ –> increase force of contraction and increase O2 and energy demand. Also some Beta 2 activity. Vasodilator vessels and lowers peripheral vascular resistance. NOT APPROPRIATE FOR CHRONIC HF. Tachyphylaxis (tolerance) SE: tachycardia, palpitations, and arrhythmias

Question 15

Milrinone

Answer 15

Phosphodiesterase inhibitor. Decreases the breakdown of cAMP. Leads to increase force of contraction and smooth muscle vasodilation (Inodilator). Strong vasodilator because it doesn’t bind to receptors but work intracellularly. SHOULD NOT BE USED FOR CHRONIC HF. SE: arrhythmias and hypotension

Question 16

Dopamine

Answer 16

Action dependent on dose. Uses: severe hypotension, acute HF, shock (vasodilatory, cardiogenic), and severe bradycardia. Adverse effects: tachycardia, dysrhythmias, N&V, and ischemia of digits and various organ systems

Question 17

Low dose dopamine (<3mcg/kg/min)

Answer 17

Stimulates renal dopamine receptors. Vasodilation (increases renal blood flow) and increased natriuresis (increased Na elimination)

Question 18

Moderate dose dopamine (4-10 mcg/kg/min)

Answer 18

Primary action Beta 1 receptors. Increase cAMP –> increase intracellular Ca2+ –> increased contractility and HR –> Increased CO

Question 19

High dose dopamine (>10mcg/kg/min)

Answer 19

Primary action is on alpha 1 receptors. Increase in vascular intracellular Ca2+ –> vasoconstriction –> increased SVR –> increased blood pressure

Question 20

Vasopressors: epinephrine

Answer 20

Balanced B1, B2, and A1 adrenergic agonist. Increased contractility, HR, and SVR

Question 21

Vasopressor: phenylephrine

Answer 21

Potent A1 agonist. (No beta). Increases SVR

Question 22

Digoxin

Answer 22

Blocks Na-K ATPase which prevents Na from leaving the cell which blocks the Na-Ca exchanger and increases intracellular calcium. Used for atrial fib/flutter and HF with reduced EF. Narrow therapeutic window (0.5-2.0 ng/ml)

Question 23

Vasopressor: Norepinephrine

Answer 23

Potent A1 and modest B stimulation (1>2). A1 = vasoconstriction (increased SVR increased BP) and B = Increased CO but HR is mostly unchanged.