Chapter 22- Positive Inotropic Drugs

Question 1

Atrial fibrillation

Answer 1

A common cardiac dysrhythmia involves atrial contraction that are so rapid that they prevent full depolarization of myocardial fibres between heart beats.

Question 2

Automaticity

Answer 2

A property of specialized excitable tissue that allows self-activation through the spontaneous development of an action potential, as in the pacemaker cells of the heart.

Question 3

Cardiac glycosides

Answer 3

Glycosides (Carbohydrates that yield a sugar and a nonuser upon hydrolysis) that are derived from the plant species Digitalis purpurea and are used in the treatment of heart disease.

Question 4

Chronotropic drugs

Answer 4

Drugs that influence the rate of the heart beat.

Question 5

Dromotropic drugs

Answer 5

Drugs that influence the conduction of electrical impulses

Question 6

Ejection fraction

Answer 6

The proportion of blood that is ejected during each ventricular contraction compared with the total ventricular filling volume.

Question 7

Heart Failure

Answer 7

The heart is unable to pump blood in sufficient amounts from the ventricles to meet the body’s metabolic needs. Symptoms depend on cardiac area affected: Left Ventricular failure= most common due to hypertension, often leads to R ventricular failure.
An abnormal condition in which cardiac pumping is impaired as the result of myocardial infraction, ischemic heart disease, or cardiomyopathy.

Question 8

Inotropic drugs

Answer 8

Drugs that affect the force or energy of muscular contractions, particularly contraction of the heart muscle.

Question 9

Left ventricular end-diastolic volume

Answer 9

The total amount of blood in the ventricle before it contracts, or the preload.

Question 10

Phosphodiesterase inhibitors

Answer 10

A group of inotropic drugs that work by inhibiting the enzyme phosphodiesterase.

Question 11

Refractory period

Answer 11

The period during which a pulse generator is unresponsive to an input signal of specified amplitude and it is impossible for the myocardium to respond.

Question 12

Therapeutic Window

Answer 12

The range of drug levels in the blood that is considered beneficial as opposed to toxic or ineffective.

Question 13

Cardiac Glycosides

Answer 13

Ex) Digoxin (Lanoxin). Narrow therapeutic window

Question 14

Cardiac Glycosides Mech of Action

Answer 14

Increase myocardial contractility. Results in reduced heart rate and improved cardiac efficiency.
Increase stroke volume
Reduction in heart size during diastole
Decrease in vein engorgement
Increase in coronary circulation

Question 15

Positive inotropic effect

Answer 15

Increase in force and velocity of myocardial contraction

Question 16

Negative chronotropic effect

Answer 16

Reduced heart rate

Question 17

Cardiac Glycosides Indication

Answer 17

Heart failure. Supra ventricular dysrhythmia- Atrial fibrillation and atrial flutter

Question 18

Cardiac Glycosides Contraindications

Answer 18

Drug Allergy, sub aortic stenosis

Question 19

Cardiac Glycosides Adverse Effects

Answer 19

Narrow therapeutic index
Low potassium levels increase its toxicity
Electrolyte levels must be monitored
Bradycardia- Check HR for a full minute (60-100)
Coloured vision, halo vision
Anorexia, nausea, vomiting, diarrhea

Question 20

Digoxin Toxicity

Answer 20

Digoxin Immune Fab (Digibind) therapy.
Hyperkalemia- greater than 5mmol/L
Life-threatening cardiac dysrhythmias - symptomatic
Life-threatening digoxin overdoes

Question 21

Predisposing conditions to Digoxin toxicity

Answer 21

Hypokalemia (low potassium)
Cardiac pacemaker
Hypercalcemia- makes bradycardic

Question 22

Phosphodiesterase Inhibitors

Answer 22

ex) Milrinone

Increase contractility= vasodilation=hypotension

Question 23

Phosphodiesterase Inhibitors Indications

Answer 23

Short-term management of heart failure

Question 24

Phosphodiesterase Inhibitors Contraindications

Answer 24

Drug Allergy, presence of severe aortic or pulmonary valvular disease

Question 25

Phosphodiesterase Inhibitors Adverse Effects

Answer 25

Hypotension

Question 26

Phosphodiesterase Inhibitors Interactions

Answer 26

Diuretics=hypovolemia

digoxin (Lanoxin)=potentiates inotropic effects

Question 27

Nesiritide (Natrecor)

Answer 27

Synthetic recombinant version of BNP (synthetic hormone)
Vasodilating effects on both arteries and veins
A final effort to treat severe, life-threatening acute heart failure.

Question 28

Positive Inotropic Drugs Nursing Implications

Answer 28

Assess history, allergies, contraindications, BP, apical pulse for 1 full minute, heart and breath sounds, weight, labs, notify doctor of S&S of toxicity (anorexia, nausea, vomiting, visual disturbances).
Avoid giving Digoxin with high-fibre foods (fibre binds with digitalis)
Monitor for therapeutic effects- Increased urinary output, decreased edema, SOB, dyspnea, crackles, and fatigue.