Unit 3,4 Flashcards
What do positive inotropic agents do?
Stimulate the heart and increase the strength of the cardiac muscle contractions.
Name four types of positive inotropic agents.
- Cardiac glycosides
- Catecholamines
- Benzimidazole Pyridazinones
- Methylxanthines
What is the primary treatment use of cardiac glycosides like Digoxin?
Treatment for heart failure.
How do cardiac glycosides strengthen myocardial contraction?
By increasing calcium ions and slowing heart rate.
What enzyme do cardiac glycosides block to affect calcium ion release?
The enzyme that reduces cellular release of calcium ions during repolarization.
What are common signs of toxicity in patients taking cardiac glycosides?
- Anorexia
- Vomiting/diarrhea
- Muscle weakness
- CNS depression/confusion
- Cardiac arrhythmia
List three clinical uses of digitalis compounds.
- Congestive heart failure (CHF)
- Atrial fibrillation
- Supraventricular tachycardia
What are catecholamines?
Injectable synthetic forms of naturally occurring neurotransmitters.
Name three examples of catecholamines.
- Epinephrine
- Dopamine
- Dobutamine
What is the primary action of catecholamines on the heart?
Increase heart rate, blood pressure, and strength of contractions.
What is Pimobendan commonly used for?
Treatment of CHF secondary to dilated cardiomyopathy or chronic mitral valve insufficiency.
What are the side effects of Benzimidazole Pyridazinones like Pimobendan?
- Anorexia
- Lethargy
- Diarrhea
What is the action of Methylxanthines such as Theophylline?
Mild positive inotropic effect and act as bronchodilators.
What do antiarrhythmics aim to correct?
Electrical disturbances within the heart.
Classify antiarrhythmics into four classes.
- Class IA
- Class IB
- Class II
- Class IV
What is the primary use of Class IA antiarrhythmics like Quinidine?
Treat atrial and ventricular arrhythmias.
How does Lidocaine act as a Class IB antiarrhythmic?
Stabilizes myocardial cell membranes and blocks sodium entrance into cells.
What is the function of Class II beta blockers?
Block actions of the sympathetic nervous system on the heart.
List two examples of Class II beta blockers.
- Propranolol
- Atenolol
What do Class IV calcium-channel blockers do?
Depress contractile mechanism of the heart and impulse transmission.
Name two examples of Class IV calcium-channel blockers.
- Amlodipine
- Diltiazem
What is the primary action of vasodilator drugs?
Dilate arteries, veins, or both to decrease afterload and improve cardiac output.
How does Hydralazine function as a vasodilator?
Reduces peripheral resistance to improve cardiac output.
