Algorithmic triage of acute heart rates > 100–150 bpm: stability screen (immediate cardioversion if unstable), narrow vs wide QRS differentiation, Brugada VT rules, and sinus tachycardia etiology search.
New tachycardia (heart rate > 100 bpm, particularly > 140–150 bpm) in the critically ill patient is a high-yield diagnostic and therapeutic fork. The primary clinical decision is assessing hemodynamic stability: if unstable (hypotension, acute heart failure, ischemic chest pain, altered mental status), immediate synchronized electrical cardioversion is required. If stable, algorithmic differentiation based on QRS width (narrow < 120 ms vs wide ≥ 120 ms) and regularity guides safe intervention.
Caution
Dangerous Diagnosis Not to Miss: Monomorphic Ventricular Tachycardia (assume every wide-complex tachycardia is VT until proven otherwise), Pre-Excited Atrial Fibrillation (WPW with irregular wide QRS at rates > 200 bpm), and Sinus Tachycardia masking occult internal hemorrhage, septic shock, or acute pulmonary embolism.
AF with RVR: unstable means electricity; stable means phenotype-directed rate/rhythm control
Treat the patient and the precipitant, not just the ventricular rate; unstable AF requires synchronized cardioversion.
Signs of Instability: Hypotension (MAP < 65), acute pulmonary edema, acute myocardial ischemia (angina, ST-segment shifts), or altered mental status.
Unstable Management: Immediate Synchronized Electrical Cardioversion (Narrow Regular: 50–100 J; Narrow Irregular [AF]: 120–200 J; Wide Regular [Monomorphic VT]: 100 J biphasic). Ensure SYNC mode is engaged.
Sinus Tachycardia: Physiologic compensatory response to fever, pain, shock, hypovolemia, hypoxia, anemia, or exogenous catecholamines. DO NOT suppress pharmacologically; identify and treat the underlying trigger.
SVT (AVNRT / AVRT): Sudden onset/termination, rate 150–220 bpm, p-waves buried. Treat with vagal maneuvers -> IV Adenosine (6 mg rapid IV push, then 12 mg if needed).
Atrial Flutter: Fixed AV block (classic 2:1 block at rate ~150 bpm with sawtooth F-waves in leads II, III, aVF).
New-Onset Atrial Fibrillation in Critical Illness (AF-CI): Rate control with short-acting beta-blockers (Esmolol/Metoprolol) or non-dihydropyridine CCBs (Diltiazem) if LV function is preserved. In reduced ejection fraction (EF < 40%) or borderline shock, use IV Amiodarone or IV Digoxin.
Multifocal Atrial Tachycardia (MAT): ≥ 3 distinct P-wave morphologies; common in severe COPD exacerbation; treat with oxygen, bronchodilators, and magnesium.
Caution
Common Diagnostic Trap: Treating compensatory sinus tachycardia with rate-controlling medications (beta-blockers/diltiazem). In septic shock, hypovolemia, or acute PE, sinus tachycardia maintains cardiac output (CO = HR x SV); suppressing heart rate precipitates profound cardiogenic collapse.
Arrhythmias: Full diagnostic criteria, Brugada algorithms, and antiarrhythmic dosing.
Shock: Hemodynamic monitoring and perfusion endpoints in tachycardia.
Cardiogenic Shock: Arrhythmogenic pump failure and inotrope selection.
Pulmonary Embolism: S1Q3T3 patterns and RV strain in tachycardia.
Hyperkalemia: Conduction abnormalities and membrane stabilization.
Evidence status
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From confirming true hypoxemia to identifying the underlying mechanism.
From recognizing hypoperfusion and initial crystalloid bolus to dynamic fluid responsiveness assessment and vasopressor targets.
From first-line norepinephrine titration to multi-agent vasopressor escalation and inotrope selection.
From multi-vasopressor failure to rescue non-adrenergic agents and mechanical circulatory support.
Algorithmic tachy- and bradyarrhythmia management, new-onset ICU atrial fibrillation, wide-complex tachycardia differentiation, and refractory Torsades overdrive pacing protocols.
Cellular dysoxia, DO2/VO2 physiology, the 4 shock phenotypes, dynamic fluid responsiveness (PLR/PPV) vs fluid tolerance (VExUS), and vasoactive pharmacology.
Primary pump failure, SCAI staging (A–E), PAC hemodynamics (CPO, PAPi), inotrope selection, emergent revascularization, and mechanical circulatory support.
Pulmonary vascular occlusion, acute RV pressure overload, ESC/AHA risk stratification, systemic thrombolysis, catheter-directed therapies, and hemodynamic support.
Nernst resting potential mechanics, ECG progression, the 3-step resuscitation framework (Stabilize, Shift, Eliminate), and post-dialysis rebound kinetics.
Bedside recognition and organ-support priorities for thyroid storm, myxedema coma, adrenal crisis, pheochromocytoma crisis, and severe hypercalcemia.
Life-threatening organ dysfunction caused by a dysregulated host response to infection — recognized by an acute rise in SOFA score, not by infection plus fever alone.