CHAPTER 22 – OVERVIEW OF THE HEART AND DRUGS AFFECTING CARDIAC FUNCTION

Question 1

Mrs Dy, a 75 year old female, normally enjoys good health. She has been treated with digoxin for atrial fibrillation for the past 10 years but maintains an independent and socially active life. For the past 5 days she has been feeling unwell and had vomited frequently in the last 24 hours. She calls the retirement village nurse who visits her immediately and ascertains that Mrs DY feels nauseous, has lost appetite and is a little confused and agitated. The nurse takes her pulse and is immediately concerned about the bigeminal rhythm. Mrs DY is taken to hospital where blood sample is drawn for electrolytes and for digoxin plasma concentration.

Answer 1

Mrs Dy, a 75 year old female, normally enjoys good health. She has been treated with digoxin for atrial fibrillation for the past 10 years but maintains an independent and socially active life. For the past 5 days she has been feeling unwell and had vomited frequently in the last 24 hours. She calls the retirement village nurse who visits her immediately and ascertains that Mrs DY feels nauseous, has lost appetite and is a little confused and agitated. The nurse takes her pulse and is immediately concerned about the bigeminal rhythm. Mrs DY is taken to hospital where blood sample is drawn for electrolytes and for digoxin plasma concentration.

Question 2

1. Discuss the most likely explanation for her current gastrointestinal and CNS symptoms.

Answer 2

Adverse reactions to Digoxin is nausea, agitation, confusion thus explaining her current status

Question 3

2. Discuss the mechanism of action of digoxin and explain why she has developed a bigeminal rhythm.

Answer 3

Digoxin decreases HR and slows conduction velocity by altering electrophysiological properties of cardiac tissues. Mrs DY is suffering from Digoxin toxicity and the bigeminal rhythm is a common sign of digoxin poisoning.

Question 4

3. Discuss the exacerbating factors that may have contributed to the current situation

Answer 4

Elderly people may have age related renal or hepatic impairment and a decreased volume of distribution for digoxin.

Question 5

4. Explain why blood sample has been sent for analysis of electrolytes and to determine a plasma digoxin concentration.

Answer 5

Digoxin has a small therapeutic range and people can display toxic effects when the plasma drug concentration is within the range therefore the need for dosages to be individualised and should be assessed often.