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[Calcium inhibitors and anesthesia]
1Département d'Anesthésie-Réanimation Chirurgicale I, Hôpital B, Centre Hospitalier Universitaire, Lille.
Insights
Calcium blockers (CB) can interact with anesthetic drugs, potentially causing cardiovascular collapse. Careful monitoring and management are crucial when using CB with anesthetics, especially halogenated agents.
Area of Science:
- Cardiology
- Anesthesiology
- Pharmacology
Context:
- Calcium blockers (CB) are widely prescribed for cardiovascular conditions like hypertension and arrhythmias.
- Anesthetic agents, particularly halogenated ones, can affect cardiac function through calcium channels.
- Concurrent use of CB and anesthetics presents potential for drug interactions.
Purpose:
- To review the interactions between calcium blockers and anesthetic agents.
- To discuss the clinical implications and management strategies for patients on CB undergoing anesthesia.
- To highlight the importance of monitoring and cautious drug selection.
Summary:
- CB inhibit calcium influx, affecting cardiac and smooth muscle, with established uses in coronary heart disease, hypertension, and arrhythmias.
- Interactions with halogenated anesthetics, which also influence cellular calcium exchange, can lead to significant cardiovascular events, from collapse to mild hypotension.
- Management requires careful consideration of patient pathology, concurrent medications, and anesthetic type, with continued CB therapy often recommended.
Impact:
- Informed anesthetic management for patients on CB, minimizing risks of adverse cardiovascular events.
- Guidance on perioperative use of CB for conditions like ischemia, hypertensive crises, and arrhythmias.
- Emphasizes the need for vigilant hemodynamic and electrocardiographic monitoring during and after anesthesia.
Abstract:
Calcium blockers (CB) are routinely used. This could lead to possible interference with anaesthetic drugs. CB prevent calcium from entering the cell by inhibiting the slow voltage-dependent calcium channels. They act mostly on heart and smooth muscle. Of all the possible indications, the three that are confirmed are coronary heart disease, arterial hypertension and supraventricular rhythm disturbances. Most of the work published and the cases reported concerns interactions between CB and halogenated anaesthetic agents; the latter's actions on the heart depend on cellular calcium exchange. Also, the cardiovascular effects of these anaesthetics are similar to that of CB. Experimentally, halothane and enflurane have direct cardiac inhibitory effects similar to verapamil and diltiazem, whereas isoflurane's properties seem closer to the dihydropyridines (nifedipine and nicardipine). Giving verapamil or diltiazem increases the number of sino-atrial and atrio-ventricular blocks when using a halogenated agent. Clinically, interpreting the effects of CB during anaesthetic induction is difficult because of the pathology (coronary heart disease, cardiac failure), the other drugs (beta-blockers and nitrates) and the type of anaesthesia (emergency or elective). Interactions can give rise to anything from a severe cardiovascular collapse, requiring catecholamines, to a mild fall in blood pressure which responds well to plasma expansion, or even no effect on blood pressure. Rebound is seen on stopping CB in patients with coronary heart disease or arterial hypertension; stopping them before surgery does not therefore seem justified. However, extreme care must be taken when using halogenated agents for patients under treatment with CB and/or beta-blockers. A wary anaesthetist will be able to adapt the technique to the patient. It has been suggested that CB could be used to treat preoperatively myocardial ischaemia (diltiazem), hypertensive crises (nifedipine, nicardipine) and ventricular rhythm disturbances (verapamil); this must be done with caution, the patient being closely monitored (haemodynamic and electrocardiographic monitoring). Postoperatively, intranasal nifedipine, continuous intravenous nicardipine or diltiazem have been used to treat increases in arterial blood pressure during recovery and to adapt the cardiovascular system to the increased metabolic needs. Here again, close patient monitoring is essential. In any case, treatment with CB which has been stopped should be started up again as soon as possible.