CEN Cardiovascular Emergencies: The 18-Item Area, Look-Alike Chest Pain, and Shock

The 12 topics in the CEN cardiovascular area

The July 2026 CEN outline gives Cardiovascular Emergencies 18 of the 150 scored items, 12% in Passy's arithmetic, and lists 12 topics. Grouping them by the kind of decision they involve makes the area easier to review:

Hypovolemic and distributive shock belong to Medical Emergencies, and pulmonary embolus is listed under Respiratory, so this guide links out for those. The clinical statements below come from Merck Manual Professional Edition chapters, each cited with its review date; they explain the topics BCEN names and are not BCEN statements.

Chest pain on the CEN: ACS, aortic dissection or pericarditis

Three causes of chest pain call for very different first moves. The table puts the distinguishing findings side by side:

Sources: Merck's ACS overview, aortic dissection, pericarditis and revascularization chapters.

Two details from the dissection chapter are worth memorizing. Medications to lower heart rate, blood pressure and shear stress on the aorta start immediately, and a beta-blocker is usually the first-line drug. And a vasodilator such as nitroprusside should not be given without a beta-blocker or a nondihydropyridine calcium channel blocker, because the reflex sympathetic response raises the shear stress on the aorta. Learn the exact heart rate and pressure goals from the guideline-based reference you study with; this guide doesn't restate them. Merck also notes that a chest radiograph in suspected ACS is partly a search for the widened mediastinum that suggests dissection.

Right ventricular infarction on the CEN: when nitrates become dangerous

Merck's chapter on complications of acute coronary syndromes says right ventricular infarction usually accompanies an inferior infarction and may first show as hypotension in a patient who had been stable. Merck's acute MI chapter gives the pattern to recognize: distended neck veins, clear lung fields and hypotension. Right-sided ECG leads help confirm it.

The treatment runs against the usual chest pain routine. Volume loading with saline is often effective, while nitrates and diuretics are not used, because they reduce preload and can cause severe hypotension. Merck's summary is direct: with hypotension after an inferior STEMI, obtain right-sided leads, and if right ventricular infarction is confirmed, avoid nitrates and diuretics. Once the pattern is clear, planned CEN practice lets you drill Cardiovascular Emergencies on its own.

Cardiogenic and obstructive shock in the CEN cardiovascular area

Merck's shock chapter classifies shock by mechanism as hypovolemic, cardiogenic, obstructive or distributive. Two of the four sit in this area:

• Cardiogenic shock is low cardiac output from a primary cardiac disorder, such as myocardial infarction or an arrhythmia
• Obstructive shock comes from a mechanical problem with filling or emptying the heart: tension pneumothorax, cardiac tamponade or pulmonary embolism

Tamponade is the obstructive cause the outline names as a topic of its own in this area. The shock chapter says it is suggested by jugular venous distention, muffled heart sounds and a paradoxical pulse, and the pericarditis chapter defines pulsus paradoxus as a fall of more than 10 mm Hg in systolic pressure during inspiration. Merck calls significant tamponade "a clinical diagnosis": when it is suspected, echocardiography is done unless even a brief delay could be life threatening, and pericardiocentesis follows immediately. Tension pneumothorax looks similar but has one-sided absent breath sounds, and the CEN respiratory guide covers it. Hypovolemic and distributive shock are in the CEN medical emergencies guide.

To work through these distinctions in exam-style items, 204 Cardiovascular questions are planned for full CEN prep, each with an explanation.

Dysrhythmias and arrest: stable or unstable comes first

Merck's emergency treatment of arrhythmias chapter starts with one question: is the patient hemodynamically unstable, meaning poorly perfused, with hypotension, suspected myocardial ischemia or altered consciousness?

• Tachycardia with instability: cardioversion
• Wide-complex tachycardia, stable: treat as ventricular tachycardia
• Narrow-complex tachycardia, stable: a trial of adenosine, a nondihydropyridine calcium channel blocker, or possibly an IV beta-blocker

In cardiac arrest, Merck's adult CPR chapter gives the order: chest compressions start immediately, ventricular fibrillation and pulseless ventricular tachycardia receive an unsynchronized shock as soon as a defibrillator is available, compressions resume right after the shock, and compressions are not interrupted for more than 10 seconds. Opening the airway is the second priority after compressions begin.

One note on references. BCEN's 2026 resource list names the 2020 edition of AHA's ACLS provider manual, and BCEN doesn't say which guideline edition its items follow. Passy's CCRN cardiovascular review sets out the 2025 AHA rhythm recommendations if you want the newest wording.

Hypertension, aneurysm, limb ischemia and heart failure

Hypertensive emergency. Merck's chapter describes severe hypertension, often 180 mm Hg systolic and/or 120 diastolic or higher, with signs of target-organ damage. Pressure is lowered progressively, not abruptly, with a short-acting titratable IV drug, and Merck says normal pressure isn't needed urgently. Severe hypertension without target-organ damage doesn't require immediate reduction. For how far to lower pressure in the first hour, Passy's CCRN cardiovascular review gives the limit from the 2025 AHA/ACC blood pressure guideline.

Ruptured abdominal aortic aneurysm. Patients who survive to reach care typically arrive with abdominal or back pain, hypotension and tachycardia. Merck's AAA chapter calls for fluids and blood but describes permissive hypotension during resuscitation: pressure is not pushed back to normal, because bleeding may increase.

Acute limb ischemia. Merck's chapter lists severe pain, pallor, paresthesias, poikilothermia (coldness) and pulselessness, with paralysis often called the sixth P. Pain out of proportion to the examination, with sudden onset, is the early clue.

Acute pulmonary edema. Merck's chapter describes severe dyspnea, diaphoresis, wheezing and sometimes blood-tinged frothy sputum, treated with oxygen and ventilatory support, IV furosemide and/or nitrates, and BiPAP when hypoxia is significant.

A Passy-written CEN cardiovascular practice item

This is an original practice item, not a BCEN question.

A patient has a regular narrow-complex tachycardia at 190/min. Her blood pressure is 70/40 mm Hg, her skin is cool and clammy, and she has become confused. Which should the nurse prepare for first?

• A. Synchronized cardioversion
• B. IV adenosine
• C. Unsynchronized defibrillation
• D. A 12-lead ECG, then reassessment in 15 minutes

Preferred response: A. Hypotension and altered consciousness make this tachycardia unstable, and Merck's arrhythmia chapter gives cardioversion for tachycardia with instability. Adenosine (B) is for a stable narrow-complex tachycardia. Unsynchronized shocks (C) are for ventricular fibrillation and pulseless VT; for cardioversion, Merck's cardioversion chapter describes delivering the shock after synchronization to the QRS complex is confirmed. Waiting (D) delays care for a poorly perfused patient. The CEN priority questions guide shows the same decision order on other areas.

How to review the 18 CEN cardiovascular items

A practical plan, not a BCEN rule:

1. Review by look-alike pairs. ACS against dissection and pericarditis, tamponade against tension pneumothorax, cardiogenic against obstructive shock. Most cardiovascular reasoning is a choice between two pictures.
2. Memorize the few numbers that drive actions. ECG within 10 minutes, pulsus paradoxus above 10 mm Hg, no more than 10 seconds off the chest.
3. Use a reference from BCEN's list. The resource list includes ENA's Emergency Nursing Core Curriculum (8th edition, 2027) and Sheehy's Manual of Emergency Care (8th edition, 2024), among others.
4. Give it a week. Cardiovascular is the largest area; the CEN study plan gives it the first content week.

Test yourself on the free CEN practice questions, which include cardiovascular items. For quick review of the numbers above, 65 Cardiovascular flashcards are planned for full CEN prep; checkout isn't open yet.