A 75-year-old patient suffering from congestive hea failure accidentally ingests a toxic dose of digoxin. Clinical consequences due to the toxic effects of cardiac glycosides are likely to include
## **Core Concept**
The question tests understanding of cardiac glycoside toxicity, specifically digoxin, which is used in treating congestive heart failure and certain arrhythmias. Cardiac glycosides work by inhibiting the **Na+/K+-ATPase pump**, leading to increased intracellular calcium and enhanced cardiac contractility. However, toxicity can lead to severe clinical consequences.
## **Why the Correct Answer is Right**
Digoxin toxicity primarily affects the heart and the nervous system. The mechanism involves the inhibition of the **Na+/K+-ATPase pump** in cardiac cells, which leads to an increase in intracellular sodium and subsequently an increase in intracellular calcium through the **Na+/Ca2+ exchanger**. This increase in calcium enhances cardiac contractility but can also lead to arrhythmias and, in severe cases, cardiac arrest. Neurological symptoms can range from nausea and vomiting to confusion, seizures, and xanthopsia (yellow vision).
## **Why Each Wrong Option is Incorrect**
- **Option A:** While digoxin toxicity can cause nausea and vomiting, which could potentially lead to hypokalemia, the direct effect on potassium levels is not the primary mechanism of toxicity.
- **Option B:** This option might seem plausible due to the effect on the heart, but the specific clinical consequences listed need to align with known effects of digoxin toxicity.
- **Option C:** This option is not provided, but typically, effects like **arrhythmias** (including atrial tachycardia with AV block, ventricular tachycardia, and ventricular fibrillation) and **neurological symptoms** are key consequences.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that **hypokalemia, hypomagnesemia, and renal impairment** can increase the risk of digoxin toxicity. Additionally, digoxin toxicity can present with a variety of arrhythmias, and treatment includes stopping the drug, administering activated charcoal if ingestion was recent, and using **digoxin-specific antibody fragments (Fab)** as an antidote in severe cases.
## **Correct Answer:** .