CEN Study Guide — 2026 Edition

Cardiovascular emergencies carry the heaviest weight on the CEN outline, and they reward one habit above all others: decide first whether the patient is perfusing. Chest pain, a fast or slow rhythm, a cold leg or a low blood pressure all lead back to the same questions — is the heart filling, is it pumping, is blood getting past an obstruction — and the answer determines what the emergency nurse does in the next five minutes. This chapter follows the outline's twelve sections in order.

A. Acute coronary syndrome

Acute coronary syndrome (ACS) is the spectrum of unstable angina, non–ST-elevation MI and ST-elevation MI (STEMI). Classic heart-attack pain is pressure-like, lasts minutes and is not fully relieved by rest or nitroglycerin: "The pain most often lasts longer than 20 minutes. Rest and a medicine to relax the blood vessels (called nitroglycerin) may not completely relieve the pain of a heart attack"^[1]. The exam likes the patient who does not look like the textbook: older adults, people with diabetes and women "may have little or no chest pain" and instead report dyspnea, fatigue or weakness^[1].

Triage. ESI handbook guidance is that a patient with chest pain should have an ECG within 10 minutes, and an abnormal ECG makes the patient level 2^[2]; active chest pain suspicious for ACS is a high-risk (level 2) situation even when no immediate lifesaving intervention is needed^[2], while a chest-pain patient who needs intubation or hemodynamic support is level 1^[2]. A normal first ECG does not exclude MI — "a heart attack can also occur without ECG changes"^[1] — so serial ECGs and troponin follow; troponin shows whether heart cells have been damaged^[3].

Treatment and timing. Aspirin is given unless it is unsafe, in which case another antiplatelet is substituted^[1]. For STEMI, angioplasty "should be done within 90 minutes after you get to the hospital," and when fibrinolytics are used they are ideally given "within 30 minutes of arriving at the hospital"^[1]. Bleeding is the most common and potentially life-threatening risk of fibrinolysis, and uncontrolled severe hypertension is a listed contraindication^[4].

The trap. Nitroglycerin lowers blood pressure and can cause dizziness and fainting^[5]; it must not be combined with a phosphodiesterase-5 inhibitor such as sildenafil, whose labeling warns against use with nitrates^[6]. Always ask about erectile-dysfunction and pulmonary-hypertension drugs before the first dose.

B. Aneurysm and dissection

An aortic dissection is a tear in the inner wall that creates a false channel; the pain is sudden and "sharp, stabbing, tearing, or ripping," felt below the breastbone and moving to the back^[7]. A blood-pressure difference between the arms (or arms and legs) is a key examination finding^[7], and because the dissection can stop flow to branch vessels, patients may have stroke signs, limb ischemia or abdominal pain^[7].

Why it matters in the ED. The pain "may feel like a heart attack"^[7], and the ACS reflex — antiplatelets, anticoagulants, fibrinolytics — is exactly what a dissection cannot tolerate. The priority is to lower heart rate and blood pressure: IV antihypertensives are given, and "Beta-blockers are the medicines of first choice"^[7]. Ascending dissections go to surgery^[7].

Abdominal aortic aneurysm (AAA). Rupture presents with severe abdominal or back pain that may spread to the groin or legs, fainting, clammy skin and shock^[8]; examination may find a pulsating abdominal mass^[8]. Bleeding from an aneurysm requires surgery right away^[8]. The trap is the older patient labelled "renal colic" or "back strain" who is hypotensive.

C. Cardiopulmonary arrest

Cardiac arrest is sudden loss of heart function, breathing and consciousness; a person in arrest "needs to be treated with a defibrillator right away"^[9]. Ventricular fibrillation causes immediate collapse^[10] and is treated with an electric shock that "should be done as quickly as possible"^[10].

High-quality CPR is what keeps the brain alive until the shock: compressions at 100 to 120 per minute to a depth of about 2 to 2¼ inches (5 to 6 cm)^[10], full chest recoil after each compression^[11], pauses under 10 seconds^[11], and a change of compressor every 2 minutes to prevent fatigue^[11]. Permanent brain damage can begin within about 4 minutes of absent blood flow^[11]. In suspected opioid arrest, naloxone may be given without interfering with CPR^[11].

How it is tested. Questions ask what comes first (the shock for a shockable rhythm, compressions for everything else), what interrupts compressions least, and who does what on a resuscitation team. The trap is any option that pauses compressions for a non-essential task.

D. Dysrhythmias

Manage the patient, not the monitor: the same rhythm is handled differently when the patient is stable or unstable. When an arrhythmia is serious, urgent treatment may include "Electrical therapy (defibrillation or cardioversion)," a temporary pacemaker, or IV medicines^[12].

• Atrial fibrillation — the rate may reach 250 to 350 and is very often over 100^[13]. The irregular rhythm "makes blood clots more likely to form," which is why stroke prevention with anticoagulation is central^[13]; but blood thinners raise bleeding risk, so not everyone can take them^[13]. Cardioversion can restore rhythm right away^[13].
• PSVT — rates may exceed 250^[14]. In a stable patient, vagal manoeuvres such as the Valsalva manoeuvre come first^[14]; emergency treatment includes IV medicines and electrical cardioversion^[14].
• Ventricular tachycardia — a rate over 100 from a ventricle with at least three beats in a row^[15]. A patient with VT who is in distress may need CPR or cardioversion^[15]; low potassium is a recognised trigger^[15], and torsade de pointes is often medication-related^[15].
• Bradycardia — dangerous when the heart cannot pump enough blood^[16]. Look for beta-blockers, calcium-channel blockers and other culprit drugs^[16]; emergency treatment uses atropine or other chronotropes and pacing^[16].

The trap: treating a number. A heart rate of 150 in a patient who is talking and perfusing is not an indication for an immediate shock; a heart rate of 40 with hypotension and confusion is not an indication to "watch and wait."

E. Endocarditis, Myocarditis, Pericarditis

Endocarditis. Bacteria reach the valves through the bloodstream; injection drug use with unclean needles is a classic portal^[17]. Look for fever with a new or changed murmur^[17], and embolic signs such as Janeway lesions^[17] or stroke from infected fragments travelling to the brain^[17]. Blood cultures guide antibiotic choice^[17] — so they are drawn before the first dose.

Myocarditis. Usually viral^[18]; the chest pain "may resemble a heart attack"^[18] and the illness is hard to diagnose because it mimics other heart and lung diseases or the flu^[18]. Suspect it in a young patient with a recent viral illness, chest pain, dysrhythmia or new heart failure.

Pericarditis. The pain is sharp, "Often increases with deep breathing and lying flat" and "Is often relieved by sitting up and leaning or bending forward"^[19]. A pericardial friction rub is the examination finding^[19]. NSAIDs are often given with colchicine^[19]. Watch for the complication: fluid build-up and poor heart function^[19] — the path to tamponade.

F. Heart failure

Acute decompensation presents with dyspnea on exertion or after lying down^[20], crackles from fluid in the lungs^[20], distended neck veins and edema. Weight gain and leg swelling over a few days signal that the body is holding fluid and heart failure is worsening^[20]. Decompensation has triggers — ischemia, high-salt food, MI, infection, not taking medicines correctly and new dysrhythmias^[20] — and NSAIDs such as ibuprofen can make heart failure worse^[20].

In the ED: sit the patient upright, give oxygen for hypoxemia, and anticipate diuretics and vasodilators per order while you look for the trigger. The trap is the patient with hypotension and cool extremities as well as congestion: that is no longer simple fluid overload but cardiogenic shock (section L).

G. Hypertension

Severe blood-pressure elevation becomes an emergency when organs are being damaged. Malignant hypertension "is a medical emergency"^[21]; it presents with headache, blurred vision, chest pain, dyspnea and changes in mental status such as confusion or decreased alertness^[21], and it threatens brain, eyes, vessels, heart and kidneys^[21]. Treatment is in hospital with IV antihypertensives until the pressure is controlled^[21].

How it is tested. The distinction is end-organ damage, not the number. A patient with 210/120 and no symptoms is managed very differently from a patient with 190/110 and new confusion. In the emergency, pressure is lowered in a controlled way with titratable IV agents under continuous monitoring — never by an unmonitored oral bolus and discharge.

H. Pericardial tamponade

In tamponade, "blood or fluid collects in the sac surrounding the heart. This prevents the heart ventricles from expanding fully"^[22]. Causes include dissection, MI, heart surgery, pericarditis and wounds to the heart^[22]. The examination findings are the ones the exam expects you to connect: neck veins that bulge "but the blood pressure is low"^[22], faint heart sounds^[22], tachycardia, and blood pressure that falls with deep breathing (pulsus paradoxus)^[22]. Bedside echocardiography is the test of choice^[22].

Priorities. The fluid "must be drained as quickly as possible"^[22]; death can occur quickly if it is not^[22]. While drainage is set up, IV fluids are given to keep the pressure up^[22]. The trap is reading distended neck veins as heart failure and reaching for a diuretic — which removes the preload a compressed heart depends on.

I. Peripheral vascular disease (e.g., venous and arterial)

Arterial. Acute arterial occlusion from an embolus — very often from atrial fibrillation^[23] — produces a painful, pale, numb limb with decreased or absent pulse and blood pressure^[23]. Anticoagulation prevents new clot^[23] and embolectomy removes the clot^[23]; the limb is kept level or slightly dependent, never elevated or warmed. Chronic peripheral artery disease causes claudication — leg pain on walking or climbing stairs^[24].

Venous. Chronic venous insufficiency causes swelling and slow-healing ulcers; compression stockings "gently squeeze your legs to move blood up your legs"^[25]. The trap is to confuse the two: compression and elevation help venous disease and harm an ischemic arterial limb.

J. Thromboembolic disease

Deep vein thrombosis causes swelling, pain or tenderness of a limb^[26] and is confirmed with Doppler ultrasound^[26]; its danger is pulmonary embolism, "which may be fatal"^[26]. PE classically causes sudden dyspnea and chest pain that "Often gets worse with deep breathing"^[27]. When PE is severe and life-threatening, clot-dissolving (thrombolytic) therapy or thrombectomy may be used^[27]. The exam tests the unstable PE as obstructive shock (section L) and the stable DVT as a diagnostic-pathway question.

K. Cardiovascular trauma

Blunt cardiac injury (myocardial contusion) follows car crashes, pedestrian strikes and even CPR; a severe contusion may look like a heart attack^[28], and ventricular dysrhythmias are a key finding^[28]. Most patients are "closely monitored for at least 24 hours" with continuous ECG^[28].

Blunt aortic injury follows rapid deceleration — "hitting the steering wheel of a car during an accident" is a named risk for dissection^[7]. Penetrating cardiac wounds cause tamponade^[22]: any wound near the heart with hypotension, distended neck veins and muffled sounds is tamponade until proven otherwise.

L. Cardiogenic shock and obstructive shock

Shock is inadequate blood flow to the body^[29]. Cardiogenic shock occurs "when the heart is unable to supply as much blood as the body needs"^[30], most often around an MI, with systolic pressure most often below 90 mm Hg^[30], cool clammy skin and pulmonary congestion. Treatment is to fix the cause quickly^[30] — for MI, catheterization with angioplasty and stenting^[30] — with inotropes and vasopressors as a bridge.

Obstructive shock is caused "by something outside of the heart which prevents the heart from pumping enough blood"^[29]: tamponade, tension pneumothorax, massive PE. The treatment is to remove the obstruction — drain, decompress, lyse — not to give inotropes to a heart that cannot fill.

Sources cited in this excerpt

1. Heart attack: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000195.htm
2. Emergency Severity Index (ESI) Handbook, Fifth Edition. Emergency Nurses Association (Emergency Severity Index Handbook, 5th edition). https://californiaena.org/wp-content/uploads/2023/05/ESI-Handbook-5th-Edition-3-2023.pdf
3. Acute coronary syndrome: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/007639.htm
4. Thrombolytic therapy: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/007089.htm
5. Nitroglycerin Sublingual: MedlinePlus Drug Information. U.S. National Library of Medicine. https://medlineplus.gov/druginfo/meds/a601086.html
6. Sildenafil: MedlinePlus Drug Information. U.S. National Library of Medicine. https://medlineplus.gov/druginfo/meds/a699015.html
7. Aortic dissection: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000181.htm
8. Abdominal aortic aneurysm: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000162.htm
9. Sudden Cardiac Arrest | MedlinePlus. U.S. National Library of Medicine. https://medlineplus.gov/cardiacarrest.html
10. Ventricular fibrillation: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/007200.htm
11. CPR - adult and child after onset of puberty: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000013.htm
12. Arrhythmias: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/001101.htm
13. Atrial fibrillation and atrial flutter: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000184.htm
14. Paroxysmal supraventricular tachycardia (PSVT): MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000183.htm
15. Ventricular tachycardia: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000187.htm
16. Slow heart rate - bradycardia: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/007856.htm
17. Endocarditis: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/001098.htm
18. Myocarditis: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000149.htm
19. Pericarditis: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000182.htm
20. Heart failure: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000158.htm
21. Malignant hypertension: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000491.htm
22. Cardiac tamponade: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000194.htm
23. Arterial embolism: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/001102.htm
24. Peripheral Arterial Disease | MedlinePlus. U.S. National Library of Medicine. https://medlineplus.gov/peripheralarterialdisease.html
25. Venous insufficiency: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000203.htm
26. Deep vein thrombosis: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000156.htm
27. Pulmonary embolus: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000132.htm
28. Myocardial contusion: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000202.htm
29. Shock: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000039.htm
30. Cardiogenic shock: MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000185.htm