一位心衰竭病史的病人被處方 beta-blocker，護理師應監測下列何種副作用？

Beta-blocker（如 Metoprolol）透過阻斷交感神經受體，達到降低心率、心肌收縮力與血壓的效果。對於心衰竭病人，這是標準治療藥物。然而，因其直接降低心率的作用，最常見的副作用就是心搏過慢。護理師在給藥前必須確實測量心跳，若心率低於特定標準（通常為 60 bpm），則需暫停給藥並諮詢醫師。

Beta-blockers such as metoprolol block sympathetic receptors, lowering heart rate, myocardial contractility, and blood pressure. They are a standard treatment for heart failure. Because they directly slow the heart rate, bradycardia is the most common adverse effect. The nurse must check the heart rate before administration; if it is below the threshold (typically 60 bpm), the dose should be held and the provider consulted.