Initial Management of Severe Dizziness, Tachycardia, and Fainting Sensation
Immediately assess hemodynamic stability and proceed directly to synchronized cardioversion if the patient shows acute altered mental status, ischemic chest pain, acute heart failure, hypotension, or shock—do not delay for diagnostic workup. 1, 2
Immediate Stabilization (First 2-3 Minutes)
Attach cardiac monitor, obtain vital signs, establish IV access, and assess oxygen saturation immediately upon patient arrival. 1, 2 These steps occur simultaneously while determining stability status.
- Check for signs of hemodynamic instability: acute altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or shock 1, 2
- Assess respiratory status: evaluate work of breathing and check pulse oximetry 1
- Provide supplemental oxygen if oxygen saturation is inadequate or respiratory distress is present, as hypoxemia commonly drives tachycardia 1, 3
Stability-Based Management Algorithm
If Patient is UNSTABLE (any of the above instability signs present):
Perform immediate synchronized cardioversion without waiting for 12-lead ECG. 1, 2 This is the critical decision point that determines mortality risk.
- Sedate the patient prior to cardioversion if conscious and time permits 1
- For wide-complex tachycardia, presume ventricular tachycardia and cardiovert immediately 1, 2
- Consider precordial thump only for witnessed, monitored unstable ventricular tachycardia if defibrillator is not immediately ready 1
If Patient is STABLE:
Obtain 12-lead ECG to define the rhythm while continuing monitoring 1, 2
Critical Rhythm Assessment:
Determine if heart rate is ≥150 bpm: This threshold indicates a likely primary arrhythmia requiring immediate workup rather than physiologic response 3
- Below 150 bpm, tachycardia is more likely secondary to underlying stress (fever, dehydration, pain, anxiety) unless ventricular dysfunction exists 3
Assess QRS complex width:
- Narrow-complex regular tachycardia: Administer adenosine 6 mg rapid IV push, followed by 12 mg if needed 1
- Wide-complex tachycardia: Use IV adenosine for both treatment and diagnosis of regular monomorphic wide-complex tachycardia of uncertain origin 1
- Consider amiodarone 150 mg IV over 10 minutes for ventricular tachycardia 1
Identify and Address Reversible Causes
While initiating treatment, identify potential reversible causes including hypoxia, electrolyte disturbances (particularly hypokalemia and hypomagnesemia), myocardial ischemia, and drug effects 1, 4
Assessment for Transient Loss of Consciousness (TLoC)
Given the "fainting sensation," consider whether this represents:
- Uncomplicated vasovagal syncope if there are "3 Ps": posture (prolonged standing), provoking factors (pain, medical procedure), or prodromal symptoms (sweating, feeling warm) 5
- Orthostatic hypotension: Check for postural vital sign changes 5
- Cardiac arrhythmia as cause of near-syncope: Requires ambulatory ECG monitoring if episodes are recurrent 5
Critical Pitfalls to Avoid
- Never delay cardioversion in unstable patients while obtaining 12-lead ECG 1, 2
- Never use AV nodal blocking agents (adenosine, calcium blockers, beta-blockers) in pre-excited atrial fibrillation or flutter, as this accelerates ventricular response 1, 2
- Never give adenosine for irregular or polymorphic wide-complex tachycardia 1, 2
- Never normalize heart rate in compensatory tachycardia where cardiac output depends on the rapid rate 1, 2
- Never combine multiple AV nodal blocking agents with overlapping half-lives, which causes profound bradycardia 1, 2
Urgent Specialist Referral Indications
Arrange urgent cardiovascular specialist assessment for patients with TLoC who have ECG findings suggesting inherited cardiac conditions (long QT syndrome), TLoC during exercise, history or physical signs of heart failure, ECG abnormalities, or structural heart disease 5