Clinical manifestations of digitalis poisoning

It is usually the earliest manifestation of digitalis poisoning, manifested by nausea, vomiting, and loss of appetite, among which loss of appetite is the first to appear, and sometimes diarrhea may occur. It is generally difficult to determine whether this symptom is caused by digitalis poisoning. It is necessary to carefully observe the changes in the patient's condition and eliminate other possible causes. For example, blood accumulation in the systemic venous system during right heart failure and insufficient oxygen in the digestive tract can also cause this digestive tract symptom.

The gastrointestinal reaction during digitalis poisoning is believed to be not the result of direct irritation of the gastrointestinal mucosa by digitalis drugs, but the result of digitalis acting on the emetic effectors in the posterior pole of the medulla oblongata, reflexively causing vomiting. For elderly people who have recovered from digitalis poisoning, due to their slowness, the first symptoms may not be nausea or vomiting, so attention should be paid.

Central nervous system symptoms: may include dizziness, headache, fatigue, mental confusion, mental disorder, yellow vision, green vision, etc. Fatigue, sleepiness, and mental confusion may occur earlier, especially in older patients. During the treatment process of heart failure, patients may also experience these symptoms due to the imbalance of water, electrolyte solutions, acid and alkali, and should be carefully identified.

Cardiac toxicity: Cardiac toxicity is easy to attract the attention of clinicians and be identified, and is usually related to the severity of such toxicity. The main side effects of cardiac toxicity are arrhythmias, including abnormalities in the generation and transmission of desire.

Digitalis causes arrhythmia in the following ways:

Blood pressure shortens the effective refractory period of the ventricular and atrial muscles, accelerates the rate of automatic depolarization in the left ventricular phase of phase 4 of the action potential, and causes increased fluid regulation in the ventricular and atrial muscles, especially increased ventricular fluid regulation, which can lead to frequent ventricular premature beats, ventricular bigeminy, trigeminy, multifocal ventricular premature beats, ventricular tachycardia (VT) and ventricular fibrillation.

The blood increases the support of the sympathetic nerves, and at the same time can directly inhibit the transmission of the atrioventricular node, and can increase the responsiveness of the sinus node and atrioventricular node to the sympathetic nerves and acetylcholine, thus causing sinus arrest, sinoatrial block, high aspect ratio or even complete atrioventricular block.