Acute Coronary, Valvular, Rhythm & Aortic Emergencies
Key Takeaways
Cerebral T waves and elevated troponin do not exclude an acute coronary occlusion.
Unstable tachyarrhythmia or severe bradycardia requires immediate hemodynamic management while the cause is investigated.
Acute severe valve dysfunction can cause shock without the loud murmur expected in chronic disease.
Acute aortic dissection can present with focal neurologic deficits; antithrombotic or thrombolytic treatment can be hazardous.
Cardiac Physiology as a Clinical Decision Tool
Cardiac output equals heart rate multiplied by stroke volume. Stroke volume depends on preload, contractility, afterload, and valve function. A higher arterial pressure after a pure vasoconstrictor does not necessarily mean that cardiac output or tissue oxygen delivery improved. Conversely, reducing excessive afterload can improve forward flow in selected patients but may sacrifice cerebral perfusion if systemic pressure falls too far.
The outline includes acute coronary syndromes, valvular disorders, arrhythmias, pacing, and aortic dissection. In a neurologically impaired patient, ischemic chest pain may be unreportable. New pulmonary edema, unexplained shock, ventricular arrhythmia, ECG changes, or regional wall motion abnormalities may therefore be the presenting clues. Evaluate the cardiac problem in parallel with the neurologic diagnosis rather than assuming that all abnormalities result from sympathetic stress.
Acute Coronary Syndrome and Its Mimics
Stress cardiomyopathy can produce marked ventricular dysfunction with relatively modest troponin elevation and wall motion abnormalities extending beyond one coronary territory. These findings raise suspicion but do not reliably exclude a concurrent coronary lesion. Obtain serial ECGs and biomarkers and assess echocardiography in context. Persistent ischemic changes, shock, or malignant arrhythmias may require urgent coronary evaluation.
Type 1 myocardial infarction reflects an acute coronary atherothrombotic event. Type 2 infarction involves ischemia from a supply-demand imbalance; elevated troponin without clinical evidence of ischemia is myocardial injury rather than automatically either type of infarction. Hypoxemia, anemia, tachycardia, hypotension, renal dysfunction, and systemic inflammation complicate interpretation in the ICU.
Antiplatelet and anticoagulant treatment can conflict with an active intracranial hemorrhage. The correct response is an urgent joint decision among cardiology and neurologic teams, considering the immediate threats and potential interventions. Neither automatic administration nor indefinite withholding of every antithrombotic is a universal answer. A recent coronary stent adds a specific risk of stent thrombosis if therapy is stopped.
Valvular and Mechanical Causes of Shock
| Problem | Physiologic consequence | Important diagnostic clue |
|---|---|---|
| Acute severe mitral regurgitation | Abrupt elevation of left atrial pressure and pulmonary edema | New shock or edema with acute ischemia or endocarditis |
| Acute aortic regurgitation | Ineffective forward flow and elevated LV filling pressure | Dissection, endocarditis, or acute valve injury |
| Severe aortic stenosis | Fixed outflow limitation and vulnerability to hypotension | Valve imaging, limited stroke-volume reserve |
| Prosthetic valve dysfunction | Obstruction, regurgitation, or embolism | New valve findings, altered anticoagulation, infection, or hemolysis |
Acute regurgitation may have a short or relatively soft murmur because pressures equalize rapidly. A reassuring auscultation does not substitute for echocardiography. TTE is the initial bedside study; TEE can be needed for prosthetic valves, suspected endocarditis, or anatomy not resolved by TTE, after considering procedural risks. Treat cardiogenic shock and obtain urgent structural or surgical assessment when a correctable lesion is suspected.
Tachyarrhythmia, Bradycardia, and Pacing
First ask whether the rhythm is causing instability: hypotension, altered consciousness, ischemia, or acute heart failure. Unstable organized tachyarrhythmias generally require synchronized cardioversion; pulseless VT or VF requires defibrillation and resuscitation. Polymorphic rhythms may require an unsynchronized shock when synchronization is impossible. Correct hypoxemia and electrolyte abnormalities and review QT-prolonging or conduction-slowing drugs.
Atrial fibrillation in critical illness can reflect infection, adrenergic stress, or fluid and cardiac disease. Rate or rhythm treatment depends on pressure, ventricular function, onset, and the risk of treatment. Avoid reflex administration of a negative inotrope in decompensated shock. Anticoagulation decisions require separate assessment of embolic and intracranial bleeding risks.
Symptomatic severe bradycardia or high-grade AV block may need medication and transcutaneous pacing while transvenous support is arranged. Confirm mechanical capture with a perfusion signal, not pacing spikes alone. Persistent high-grade block without a reversible cause can require a permanent pacemaker. If bradycardia accompanies new pupillary changes and severe hypertension, treat the intracranial emergency promptly; if it independently compromises circulation, manage both problems simultaneously.
Aortic Dissection and the Neurologic Presentation
Acute aortic dissection may involve carotid branches, spinal arteries, coronary ostia, the aortic valve, or the pericardium. A patient can present with stroke, spinal cord ischemia, syncope, limb ischemia, tamponade, or shock, sometimes without a classic pain description. Pulse or pressure asymmetry, a new regurgitant murmur, or an appropriate imaging finding heightens concern but absence of these signs does not exclude disease.
When dissection is suspected, obtain urgent appropriate aortic imaging and surgical or vascular consultation. Thrombolysis for a presumed ordinary ischemic stroke can be dangerous in this setting. In a hypertensive patient, impulse control commonly begins with rate control and then additional pressure control, while preserving organ perfusion. Hypotension demands investigation for rupture, tamponade, severe regurgitation, or malperfusion rather than routine escalation of antihypertensive drugs. Type A dissection generally requires emergency surgical evaluation.
Sources checked October 17, 2026: AHA 2025 adult advanced life support and ACC/AHA aortic disease guideline.
A new wide-complex tachyarrhythmia causes shock in a patient with a pulse. What determines the initial rhythm intervention?
The troponin result alone
Hemodynamic instability and rhythm type
Waiting for elective coronary imaging
The presence of a prior neurologic diagnosis excludes cardiac treatment
A focal neurologic deficit accompanies abrupt chest pain, asymmetric arm pressures, and a new aortic regurgitation murmur. Which diagnosis must be urgently considered before thrombolysis?
Uncomplicated delirium
Isolated myasthenic crisis
Acute aortic dissection with branch-vessel involvement
Typical absence epilepsy
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