2.4 Shock, Vascular, and Pericardial Emergencies
Key Takeaways
- Cardiogenic shock is pump failure with hypotension, cool clammy skin, and pulmonary congestion; treat with inotropes (dobutamine) and afterload reduction, NOT large fluid boluses.
- Aortic dissection is managed by lowering heart rate to about 60 with an IV beta-blocker (esmolol/labetalol) FIRST, then systolic BP to 100-120 with a vasodilator like nicardipine.
- Hypertensive emergency requires lowering mean arterial pressure by no more than about 25% in the first hour to avoid cerebral, cardiac, or renal hypoperfusion.
- Cardiac tamponade presents with Beck's triad (hypotension, jugular venous distension, muffled heart sounds) and pulsus paradoxus; the definitive treatment is pericardiocentesis.
Cardiogenic Shock
Cardiogenic shock is failure of the heart as a pump - most often after a large anterior MI - producing hypotension despite adequate or elevated filling pressures. The presentation is hypotension, cool and clammy skin, weak thready pulses, oliguria, altered mental status, and pulmonary congestion (crackles). Because the lungs are already wet, the classic trap is to give a large fluid bolus - that worsens pulmonary edema.
Management targets contractility and afterload:
- Inotropes to improve contractility: dobutamine (or dopamine) when blood pressure permits.
- Vasopressors such as norepinephrine for profound hypotension.
- Afterload reduction and mechanical support (intra-aortic balloon pump, Impella) for refractory shock.
- Definitive therapy is reperfusion of the culprit coronary artery via PCI.
Contrast with hypovolemic shock, where fluids ARE the answer - the CEN tests whether you can tell wet (cardiogenic) from dry (hypovolemic) shock.
Aortic Aneurysm, Dissection, and Hypertensive Crisis
Aortic dissection is a tear in the aortic intima allowing blood to split the wall. Classic findings: sudden tearing or ripping chest or back pain, a pulse or blood-pressure difference between arms (>20 mmHg), and a widened mediastinum on chest x-ray. The Stanford classification is high-yield: Type A involves the ascending aorta (surgical emergency); Type B is limited to the descending aorta (often managed medically).
The drug sequence is the trap: lower the heart rate first to about 60/min with an IV beta-blocker (esmolol or labetalol) to reduce shear force, then lower systolic BP to 100-120 mmHg with a vasodilator such as nicardipine or nitroprusside. Giving a vasodilator first causes reflex tachycardia that increases wall stress and can extend the dissection.
Abdominal aortic aneurysm (AAA) rupture presents with abdominal/flank pain, a pulsatile mass, and hypotension - it is a surgical emergency; avoid aggressive fluids that raise pressure and dislodge clot.
Hypertensive emergency (severe hypertension with end-organ damage) requires controlled lowering: reduce mean arterial pressure (MAP) by no more than about 25% in the first hour. Dropping pressure too fast causes cerebral, coronary, or renal hypoperfusion and stroke.
Pericarditis, Tamponade, and Endocarditis
Pericarditis causes sharp, pleuritic chest pain that is worse lying flat and relieved by sitting forward, often with a pericardial friction rub and diffuse ST elevation with PR depression across many leads (unlike the localized ST elevation of STEMI). Treatment is usually NSAIDs and colchicine.
Cardiac tamponade occurs when pericardial fluid accumulates fast enough to compress the heart and limit filling. Memorize Beck's triad:
- Hypotension
- Jugular venous distension (elevated CVP)
- Muffled or distant heart sounds
Also expect pulsus paradoxus - a drop in systolic BP greater than 10 mmHg during inspiration. Tamponade is obstructive shock; the definitive treatment is pericardiocentesis to remove the fluid, with a fluid bolus as a temporizing bridge.
Infective endocarditis is infection of the heart valves, seen in IV drug users and patients with prosthetic valves. Findings include fever, a new or changed murmur, and peripheral embolic signs: Janeway lesions (painless), Osler nodes (painful), splinter hemorrhages, and Roth spots. Blood cultures and long-course IV antibiotics are the mainstay.
Peripheral arterial occlusion presents with the 6 Ps: pain, pallor, pulselessness, paresthesia, paralysis, and poikilothermia (coolness) - a limb-threatening emergency requiring anticoagulation and urgent revascularization.
Venous Emergencies and Vascular Distinctions
The CEN also contrasts arterial with venous vascular emergencies, which have opposite findings and treatments:
| Feature | Acute arterial occlusion | Deep vein thrombosis (DVT) |
|---|---|---|
| Onset | Sudden | Gradual over hours to days |
| Skin | Pale, cool, mottled | Red, warm, swollen |
| Pulses | Diminished or absent | Present |
| Pain | Severe, distal | Aching, calf, with swelling |
| Threat | Limb loss within hours | Pulmonary embolism |
Deep vein thrombosis presents with unilateral leg swelling, warmth, redness, and tenderness. The feared complication is pulmonary embolism (PE) - sudden dyspnea, pleuritic chest pain, tachycardia, hypoxia, and in massive PE, obstructive shock and PEA arrest. Treatment of DVT/PE is anticoagulation (heparin, then oral agents); massive PE with hemodynamic compromise may receive fibrinolytics. A key teaching point: never massage a suspected DVT - it can dislodge the clot.
Differentiating the Shock States
Many cardiovascular CEN items reduce to identifying the type of shock, because the treatment diverges sharply:
- Cardiogenic (pump failure): hypotension with pulmonary congestion and cool skin - give inotropes, reduce afterload, reperfuse; avoid large fluids.
- Obstructive (tamponade, tension pneumothorax, massive PE): hypotension with distended neck veins - relieve the obstruction (pericardiocentesis, needle decompression, thrombolysis).
- Hypovolemic (hemorrhage, dehydration): hypotension with flat neck veins and dry mucosa - give fluids and blood.
- Distributive (septic, anaphylactic, neurogenic): warm or vasodilated, low systemic vascular resistance - fluids plus vasopressors.
The quick discriminator is the neck veins: distended in cardiogenic and obstructive shock, flat in hypovolemic shock. Pairing that single finding with the lung exam lets you separate the cardiovascular shock states the CEN tests side by side.
Pericarditis versus STEMI on the ECG
One more vascular and pericardial discriminator the exam loves is separating pericarditis from STEMI. Pericarditis produces diffuse, concave-upward ST elevation across many leads with associated PR-segment depression, and the pain is sharp, pleuritic, and positional (worse supine, better leaning forward). A STEMI produces localized, often convex ST elevation confined to one arterial territory, frequently with reciprocal ST depression in the opposite leads, and the pain is pressure-like and unaffected by position.
Treating pericarditis as a STEMI could send a patient to unnecessary fibrinolytics - dangerous if a pericardial effusion is present - while dismissing a true STEMI as pericarditis delays life-saving reperfusion. The position-dependence of the pain plus the diffuse ST pattern is the fastest tell.
A patient in cardiogenic shock after a large anterior MI has crackles throughout both lung fields and a BP of 78/50. Which intervention is most appropriate?
Which medication sequence is correct for managing acute aortic dissection?
Beck's triad is associated with which cardiovascular emergency?
When treating a hypertensive emergency with end-organ damage, by how much should the mean arterial pressure be lowered in the first hour?