CARDIAC GLYCOSIDES, ANTIANGINALS AND ANTIDYSRHYTHMICS

CARDIAC GLYCOSIDES

Actions and Uses:

Cardiac Glycosides inhibit the sodium-potassium pump resulting in an increase in intracellular sodium. This increase in intracellula sodium leads to an influx of calcium, causing the cardiac muscle fibers to contract more efficieintly. They have three effects on heart muscle- a positive inotropic action which increases the myocardial contraction stroke volume. A negative chronotropic action that decreases the heart rate and a negative dromotropic action that decreases the conduction of the heart cells. The increase in myocardial contractility increases cardiac, peripheral and kidney function by increasing cardiac output, decreasing preload, improving blood flow, decreasing edema, and increasing fluid excretion. It does not prolong life, but increases the force and velocity of myocardial systolic contraction.

Cardiac Glycosides are a secondary drug for heart failure. They are also used to correct atrial fibrilation and atrial flutter. They do this by decreasing heart rate and decreasing conduction through the atrioventricular node.

Side Effects and Adverse Effects:

Some side effects of cardiac glycosides include: anorexia, nausea, vomiting, headache, blurred vision, diplopia, photophobia, drowsiness, fatigue, and confusion. Adverse reactions include: bradycardia and visual disturbances. Some adverse reactions are life threatening. These reactions include: atrioventricular block and cardiac dysrhythmias. An overdose or accumulation of cardiac glycosides causes toxicity.


Nursing Implications:

The nurse should advise the client taking cardiac glycosides to eat foods that are rich in potassium. These foods help maintain and desired serum potassium level. Some potassium rich food choices are: fresh and dried fruits, fruit juices, and vegetables, including potatoes.

Assess the patient's vital signs, especially pulse rate daily. Do NOT administer any cardiac glycosides if the pulse rate is less than 60 bpm. Before discharging the patient, make sure that they are capable of assessing their own pulse rate and know the importance of holding the medication and immediately informing the healthcare provider if their pulse rate is less than 60 bpm.


ANTIANGINALS

Actions and uses:

Antianginal drugs are used to treat a condition of acute cardiac pain called angina pectoris. This pain is caused when inadequate bloodflow to the myocardium, or muscle layer of the heart, leads to inadequate oxygenation of the myocardium. Antianginal drugs increase blood flow increasing oxygen content of the blood or decreasing oxygen demand by the myocardium.

Side Effects and Adverse Effects:

Some side effects of antianginals include: nausea, vomiting, dizziness, syncope, weakness, confusion, rash, dry mouth, and headache. Some adverse effects include: hypotension, reflex tachycardia, and paradoxical bradycardia. A life threatening adverse effects is circulatory collapse.

Nursing Implications:

Advise a client to take a SL nitroglycerin tablet if chest pain occurs. The client needs to repeat in five minutes a second and third time, each five minutes apart, if the pain has still not been resolved. Make sure that the client is aware to not take more than three tablets and to take the tablets with five minutes between tablets. If chest pain lasts longer than fifteen minutes, consult your healthcare provider for immediate medical assistance.


Hypotension is associated with most antianginal drugs. The nurse must closely monitor the vital signs of the patient. Clients taking antianginal drugs must be instructed to take a pulse rate if dizziness or faintness occurs as these are signs of hypotension.

ANTIDYSRHYTHMICS

Actions and Uses:

Antidysrhythmic drugs are used on patients whose heart rate deviates from the normal rate or pattern. This includes bradycardia, tachycardia, or irregular heartbeats or dysrhythmias. The antidysrhythmic drug's action is to restore the cardiac rhythm to normal. Antidysrhythmic drugs do this by blocking adrenergic stimulation of the heart, depressing myocardial excitability, decreasing conduction velocity and cardiac tissue, increasing recovery time of the myocardium and suppressing automaticity.

Side Effects and Adverse Effects:

There are many side effects of antidysrhythmic drugs. These include: nausea, vomiting, diarrhea, hypotension, confusion, and dizziness. Some high doses can cause cardiovascular depression, bradycardia, seizures, blurred and double vision. Some life threatening adverse reactions include: ventricular dysrhythmias and agranulocytosis.

Nursing Implications:

Advise a client taking antidysrhythmics to avoid alcohol, caffeine and tobacco. Alcohol can intensify a hypotensive reaction. Caffeine can increase the catecholamine level, and tobacco promotes vasoconstriction.

A nurse must ensure that the client understands that medication compliance is essential. The must take their prescribed drugs as ordered.

The nurse must provide specific instructions for each drug and make certain that the client understand their instructions.

REFERENCES:
Kee, Joyce L., Hayes, Evelyn R., & McCuistion, Linda E. (2009). Pharmacology: A Nursing Process Approach (6th ed.), (pp. 623-640). St. Louis, Missouri: Saunders Elsevier

Edited by: Grant Gardner