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Cardiology
arrhythmias
sinus bradycardia
A 68-year-old woman is brought to an urgent care center by her family due to progressive fatigue, dizziness, and two episodes of near-syncope over the past 24 hours. Her medical history includes well-controlled hypertension for which she recently had a medication adjustment. On arrival, she appears pale and diaphoretic. Her vital signs are: heart rate 42 beats/minute, blood pressure 88/55 mm Hg, respiratory rate 16 breaths/minute, and oxygen saturation 96% on room air. Cardiac auscultation reveals regular bradycardic rhythm with distant heart sounds. Her peripheral pulses are weak and thready. A 12-lead electrocardiogram shows sinus bradycardia with no acute ischemic changes. Lab results are pending. Given her hemodynamic compromise, which initial pharmacological intervention is most appropriate, and what is the crucial next step if this intervention proves ineffective?
| Lab Parameter | Value | Reference Range |
|---|---|---|
| Hemoglobin | 135 g/L | 120-150 g/L |
| White Blood Cell Count | 7.8 x 10^9/L | 4.0-11.0 x 10^9/L |
| Platelets | 250 x 10^9/L | 150-450 x 10^9/L |
| Sodium | 138 mmol/L | 135-145 mmol/L |
| Potassium | 4.1 mmol/L | 3.5-5.0 mmol/L |
| Chloride | 102 mmol/L | 98-107 mmol/L |
| Bicarbonate | 25 mmol/L | 22-29 mmol/L |
| Blood Urea Nitrogen (BUN) | 8.5 mmol/L | 2.5-7.1 mmol/L |
| Creatinine | 98 µmol/L | 50-100 µmol/L |
| Glucose | 5.2 mmol/L | 3.9-6.1 mmol/L |
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