護理師即將給予心衰竭病人 digoxin 0.25 mg。給藥前，優先評估下列哪項數據？
A nurse is administering digoxin 0.25 mg orally to a client with heart failure. Before administration, which assessment finding is the priority?
- ASerum potassium level血清鉀濃度
- BBlood pressure血壓
- CRespiratory rate呼吸頻率
- DApical pulse rate✓ 正解心尖脈搏速率
Digoxin 是一種強心苷類藥物，主要透過抑制心肌細胞膜上的鈉鉀幫浦（Na+/K+-ATPase），增加心肌收縮力，同時具有負性傳導作用，能減慢房室結（AV node）的傳導。由於其治療指數狹窄且具有潛在的心律不整副作用，給藥前最關鍵的評估指標為心跳速率。若心跳過慢（成人 < 60 bpm），給藥可能加重心跳過緩或誘發致命性心律不整。
Digoxin is a cardiac glycoside that primarily inhibits the sodium-potassium pump (Na+/K+-ATPase) on the myocardial cell membrane, thereby increasing myocardial contractility. It also has a negative chronotropic effect, slowing conduction through the AV node. Because of its narrow therapeutic index and potential for cardiac dysrhythmia side effects, the most critical assessment before administration is the heart rate. If the heart rate is too slow (adult < 60 bpm), administration may worsen bradycardia or trigger fatal dysrhythmias.