What are the recommended steps for a patient experiencing dizziness, headache, and bradycardia (abnormally slow heart rate)?

Management of Dizziness, Headache, and Bradycardia

First, immediately identify and treat any reversible causes of bradycardia—medications (beta blockers, calcium channel blockers, digoxin), hypothyroidism, electrolyte abnormalities, or acute myocardial infarction—before considering permanent pacing, as this is the Class I recommendation from ACC/AHA guidelines. 1

Immediate Assessment and Stabilization

Determine if the bradycardia is causing the symptoms:

• Assess for hemodynamic compromise: hypotension (systolic BP <90 mmHg), altered mental status, signs of shock, acute heart failure, or ischemic chest pain 2
• Document the heart rate and rhythm with a 12-lead ECG immediately to identify the type of bradycardia (sinus bradycardia, AV block, sinus node dysfunction) 2
• Correlate symptoms with bradycardia timing—dizziness and headache may or may not be directly caused by the slow heart rate 1, 2

If the patient is symptomatic with hemodynamic compromise:

• Administer atropine 0.5-1 mg IV as first-line therapy, repeatable every 3-5 minutes up to a maximum total dose of 3 mg 1, 3, 4
• Caution: Doses <0.5 mg may paradoxically slow the heart rate further 3, 4
• Caution: Atropine is ineffective in heart transplant patients without autonomic reinnervation and should not be used 1, 3

If atropine fails or is contraindicated:

• Consider dopamine infusion 5-20 mcg/kg/min IV, starting at 5 mcg/kg/min and increasing by 5 mcg/kg/min every 2 minutes 1
• Alternative: epinephrine infusion 2-10 mcg/min IV or 0.1-0.5 mcg/kg/min IV titrated to effect 1
• Alternative: isoproterenol 20-60 mcg IV bolus or infusion of 1-20 mcg/min based on heart rate response 1
• Transcutaneous pacing is reasonable as a bridge to transvenous pacing if medications fail 3, 2

Identify and Reverse Underlying Causes

Medication-induced bradycardia (most common reversible cause):

• Review all medications: beta blockers, non-dihydropyridine calcium channel blockers (diltiazem, verapamil), digoxin, antiarrhythmic drugs, lithium, methyldopa, risperidone, cisplatin, interferon 1
• Withdraw or reduce the offending drug if it is not essential for another life-threatening condition 1
• For beta-blocker or calcium channel blocker overdose: administer glucagon 3-10 mg IV with infusion of 3-5 mg/h, or high-dose insulin therapy (1 unit/kg IV bolus followed by 0.5 units/kg/h infusion) 1
• For digoxin overdose: administer digoxin antibody fragment (dose dependent on amount ingested or known digoxin concentration) 1

Metabolic and systemic causes:

• Check thyroid function (TSH, free T4)—hypothyroidism commonly causes bradycardia and responds well to thyroxine replacement 1
• Check electrolytes: hyperkalemia, hypokalemia, hypoglycemia can all cause bradycardia 1
• Assess for acute myocardial infarction (especially inferior MI, which can cause bradycardia via vagal stimulation) 1
• Consider elevated intracranial pressure if headache is prominent—this can cause reflex bradycardia 1
• Screen for obstructive sleep apnea if nocturnal bradycardia is documented, as this is a common reversible cause 1

Infectious causes:

• Consider Lyme disease, legionella, typhoid fever, viral infections in appropriate clinical contexts 1

Diagnostic Workup After Stabilization

If symptoms are intermittent and not captured on initial ECG:

• Ambulatory ECG monitoring is essential to correlate symptoms with bradycardia 1, 2
• Choose monitoring duration based on symptom frequency: 24-72 hour Holter for daily symptoms, 30-day event monitor for weekly symptoms, implantable cardiac monitor for symptoms >30 days apart 1, 2

Additional testing:

• Echocardiography if structural heart disease is suspected 2
• Exercise stress testing if chronotropic incompetence (inability to increase heart rate with exertion) is suspected 2
• Electrophysiology study (EPS) may be considered if the diagnosis remains uncertain after noninvasive evaluation, but is generally not first-line 1

Long-Term Management

Permanent pacemaker indications:

• Symptomatic sinus node dysfunction that persists after reversible causes are excluded 1, 2
• High-grade AV block (second-degree Mobitz type II or third-degree) with symptoms 2
• Important: Asymptomatic bradycardia, even if severe, does NOT require pacing because the benefit of pacing is symptom relief and quality of life improvement, not mortality reduction 1

When NOT to pace:

• Asymptomatic or minimally symptomatic patients have no indication for permanent pacing, even with documented bradycardia, because pacing carries surgical risk and long-term complications 1
• Nocturnal sinus bradycardia or pauses are physiologic in many patients and do not require treatment 1
• Athletic training-induced bradycardia is physiologic and requires no intervention 1

Critical Pitfalls to Avoid

• Do not assume bradycardia is the cause of symptoms without documenting temporal correlation—symptoms may be unrelated 1, 2
• Do not use atropine in acute coronary ischemia without caution, as increased heart rate may worsen ischemia 3
• Do not give atropine doses <0.5 mg, as this may paradoxically worsen bradycardia 3, 4
• Do not implant a pacemaker before excluding reversible causes, as this exposes patients to unnecessary procedural risk 1
• Do not use benzodiazepines or opioids for sedation in bradycardic patients, as they can worsen bradycardia through sympatholytic effects 3