Aortic Aneurysm & Aortic Dissection

A patient reports sudden, tearing chest pain radiating to the back with unequal blood pressures in each arm. This isn't an MI — missing the distinction can be fatal.

An aortic aneurysm is a pathological dilation of the aorta (≥50% greater than normal diameter), most commonly in the abdominal aorta (AAA) below the renal arteries. Most are asymptomatic until they expand or rupture. A pulsatile abdominal mass is the hallmark finding — never palpate deeply once discovered, as this risks rupture. AAA rupture presents with sudden severe abdominal or back pain, hypotension, and tachycardia — treat as a surgical emergency. Aortic dissection is a tear in the intimal layer allowing blood to track between vessel wall layers. It presents with abrupt, severe "tearing" or "ripping" chest pain radiating to the back. The critical assessment finding is blood pressure asymmetry between arms (>20 mmHg difference), because the dissection flap can occlude branch vessels unequally. Type A dissections involve the ascending aorta (surgical emergency). Type B involve the descending aorta (often managed medically with aggressive BP and heart rate reduction targeting systolic 100–120 mmHg and HR <60 bpm). Nursing priorities: maintain hemodynamic stability, administer IV beta-blockers (labetalol, esmolol) as ordered to reduce heart rate and shearing force, monitor bilateral BPs, neuro status, and urine output for signs of malperfusion.

Key Distinctions

Don't confuse aortic dissection (tearing back pain, BP asymmetry, intact pulses may differ) with acute MI (crushing substernal pressure, diaphoresis, ST changes) — giving thrombolytics or anticoagulants to a dissection patient can be lethal. Students mix up aneurysm (dilation, often silent) with dissection (intimal tear, acute emergency). AAA screening: one-time ultrasound for men aged 65–75 who have ever smoked.

Clinical Pearl

Tearing pain plus unequal arm BPs equals dissection until proven otherwise. Never anticoagulate — the wall is already torn.