Sinus bradycardia is a heart rate slower than 60 beats/ min due to increased vagal influence on the normal pacemaker or organic disease of the sinus node. The rate usually increases during exercise or administration of atropine. In healthy individuals, and especially in patients who are in excellent physical condition, sinus bradycardia to rates of 50 beats/min or even lower is a normal finding.
However, severe sinus bradycardia (< 45 beats/min) may be an indication of sinus node pathology, especially in elderly patients and individuals with heart disease. It may cause weakness, confusion, or syncope if cerebral perfusion is impaired. Atrial, junctional and ventricular ectopic rhythms are more apt to occur with slow sinus rates. Pacing may be required if symptoms correlate with the bradycardia.
Hypertension may be due to poisoning with amphetamines, anticholinergics, cocaine, performance-enhancing products (containing caffeine, phenylephrine, ephedrine, or yohimbine), monoamine oxidase (MAO) inhibitors, and other drugs. Severe hypertension (eg, diastolic blood pressure > 105–110 mm Hg in a person who does not have chronic hypertension) can result in acute intracranial hemorrhage, myocardial infarction, or aortic dissection.
Hypertensive patients who are agitated or anxious may benefit from a sedative such as lorazepam, 2–3 mg intravenously. For persistent hypertension, administer phentolamine, 2–5 mg intravenously, or nitroprusside sodium, 0.25–8 mcg/kg/min intravenously. If excessive tachycardia is present, add propranolol, 1–5 mg intravenously, or esmolol, 25–100 mcg/kg/min intravenously, or labetalol 0.2–0.3 mg/kg intravenously. Caution: Do not give betablockers alone, since doing so may paradoxically worsen hypertension as a result of unopposed alpha-adrenergic stimulation.