Final answer:
The most common cause of death in a kid who ingested TCAs is cardiovascular toxicity, which can cause life-threatening arrhythmias and cardiac arrest.
Step-by-step explanation:
The most common cause of death in a kid who ingested TCAs (Tricyclic Antidepressants) is from cardiovascular toxicity. TCAs can cause significant changes in heart rhythm and function, leading to life-threatening arrhythmias and cardiac arrest. The overdose of TCAs can also result in respiratory depression and seizures.
For example, an overdose of TCAs can block the normal sodium channels in cardiac cells, prolonging the QT interval on an electrocardiogram (ECG). This can lead to a potentially fatal arrhythmia called torsades de pointes.
It is important to note that TCA overdose is a medical emergency, requiring immediate medical attention and treatment to minimize the risk of death.