Aortic Emergencies: Dissection and Ruptured AAA

Acute aortic dissection starts with a tear in the intima. Blood gets into the aortic wall and splits the layers apart. That gap is the false lumen. It can run along the aorta, block branch vessels or burst outward. Classification tells you where to go. Stanford type A involves the ascending aorta, and that is a cardiothoracic surgical emergency. Stanford type B stays in the descending aorta and is usually treated medically unless complications develop. DeBakey types I and II cover ascending involvement, and type III is descending only. Same anatomy, different names.

Shear stress on the aortic wall is what drives the tear onward. Shear rises with high systolic pressure and with fast, forceful ejection (dP/dt). So in a stable patient, slow the heart first and lower the pressure second.

• Background: hypertension is the usual backdrop. Connective-tissue disorders like Marfan syndrome raise the risk.
• Acute aortic syndromes: the 2022 ACC/AHA guideline groups intramural hematoma and penetrating aortic ulcer with dissection. Initial medical care here follows protocol. Surgery depends on type and complications. Blunt traumatic aortic injury is its own pathway and is not covered on this page.
• Ruptured abdominal aortic aneurysm (AAA): a dilated infrarenal aorta that bursts into the retroperitoneum or peritoneum and causes hemorrhagic shock. Don't carry the dissection BP targets and beta-blocker regimens on this page over to it. The ESC 2024 guideline names hypertension and male sex as major AAA risk factors.
• Clinical course: the International Registry of Acute Aortic Dissection (IRAD) report, published in 2000, found in-hospital mortality of 27.4% overall. Mortality by type is under ED & ICU Management.

Presentations

• Typical: sudden, severe pain. In IRAD, sudden severe sharp pain was the single most common complaint. It can sit in the chest, back or abdomen.
• Atypical: syncope, stroke or focal neurologic deficit, limb ischemia, or shock with no pain. These are common ways the diagnosis gets missed.
• Ruptured AAA: sudden abdominal, flank or back pain, hypotension, and sometimes a pulsatile abdominal mass. Pain alone won't tell it apart from renal colic.

Red Flags

• SBP below 90 mmHg or hypoperfusion (confusion, cool skin, oliguria)
• Pulse or BP asymmetry between arms, or a pulse deficit in a limb
• New diastolic murmur (aortic regurgitation)
• Neurologic deficit, syncope or a limb that is cold, pale or pulseless

Imaging makes the diagnosis. The bedside exam alone does not. The table lists the early checks and what each one should trigger.

• STEMI or NSTE-ACS: dissection can look like chest pain with ischemic ECG change. Before any thrombolytic, separate the two using pulse and BP asymmetry, the character of the pain, and CTA.
• Pulmonary embolism: pleuritic pain and hypoxemia. When both are on the table, check for asymmetric BP and a dissection flap on CTA.
• Stroke: a focal deficit with sudden onset. A neurologic presentation of dissection still needs the same BP and pulse check.
• Renal colic, pancreatitis or perforated viscus: all cause abdominal pain. Hypotension or a pulsatile mass makes ruptured AAA the one to exclude.
• Pericarditis or tamponade: chest pain with a friction rub or muffled sounds. Type A dissection can cause tamponade.

1. Recognize and call early: sudden severe chest, back or abdominal pain with any Red Flag means calling ALS now.
2. Keep the patient still: seated or supine as tolerated; minimize exertion and straining.
3. Check BP and pulses in both arms and both legs when the protocol allows, and report any difference.
4. Oxygen only for hypoxemia, per protocol.
5. Medications the patient already takes: ask about PDE-5 inhibitors (sildenafil, tadalafil, vardenafil, avanafil) and riociguat before any nitrate. Assist with the patient's own prescribed medications per protocol.
6. Aspirin and anticoagulants: if dissection is suspected (sudden tearing pain, pulse or BP asymmetry, neurologic deficit), withhold them and tell the receiving facility, per protocol and medical direction (protocol-dependent); otherwise follow the chest-pain protocol.
7. Transport priority: minimize scene time; for suspected type A, go directly to a cardiothoracic surgery center.

Doses vary by protocol; follow local protocols and medical direction.

• IV access, 12-lead ECG, and continuous monitoring (Paramedic/RN/CCT). In ruptured AAA, one line is not enough.
• Hemodynamic check first (Paramedic/RN/CCT): Stable means SBP 90 mmHg or higher with no shock or tamponade. The rate and pressure regimens below apply only to that patient. If SBP is below 90 or the patient is in shock, skip to the next bullet.
• Heart rate first, stable patients (Paramedic/RN/CCT): labetalol 20 mg IV over 2 min, then 40 or 80 mg every 10 min (cumulative max 300 mg), or infusion at 2 mg/min adjusted to the BP response. Recheck BP and HR after each dose. Targets: HR 60–80 bpm and SBP below 120 mmHg, or the lowest BP that keeps organs perfused. Do not give labetalol with bronchial asthma, overt cardiac failure, heart block greater than first degree, severe bradycardia, cardiogenic shock, or severe prolonged hypotension. See Labetalol.
• Short-acting titratable alternative (ED/ICU): esmolol 500 mcg/kg IV over 1 min (optional loading dose), then 50 mcg/kg/min, titrated at intervals of at least 4 min to the label dose range. Reach for it when the effect has to wear off quickly: borderline bronchospasm, borderline LV function, possible surgery. As a beta-blocker, esmolol is contraindicated in severe sinus bradycardia, heart block greater than first degree, sick sinus syndrome, decompensated heart failure, cardiogenic shock, pulmonary hypertension, and IV verapamil or diltiazem given in close proximity. Use an arterial line where available. See Esmolol.
• Beta-blocker contraindicated or not tolerated (ED/ICU): IV verapamil or diltiazem, a non-dihydropyridine calcium-channel blocker, is the guideline alternative for heart rate control (2022 ACC/AHA, recommendation class 2a, level B-NR). Don't give it close in time to a beta-blocker dose. Together they add bradycardia and heart-block risk (see the Esmolol contraindication above). Calcium-channel blockers are generally avoided in Marfan syndrome unless needed for BP control.
• Hypotension, shock or suspected tamponade (SBP below 90 or hypoperfusion): give no beta-blocker, no vasodilator and no rate-control drug. Treat as rupture, tamponade or severe aortic regurgitation: blood or volume per protocol and immediate transfer to the surgical team. Pericardial drainage is the surgeon's call. Blind pericardiocentesis is off the table.
• Analgesia: IV opioid titrated to effect (Paramedic/RN/CCT). Fentanyl 1 mcg/kg IV, max initial 100 mcg (see Fentanyl); morphine per protocol (see Morphine). Relieving pain lowers sympathetic drive. It can also drop the BP, so reassess after each dose.
• Second agent if SBP stays above 120 mmHg after heart rate is controlled (ED/ICU): nicardipine 5 mg/hr IV, titrate up to 15 mg/hr (see Nicardipine), or clevidipine 1–2 mg/hr IV (see Clevidipine). Add these only after beta-blockade in a stable patient. A vasodilator alone drives reflex tachycardia.
• Do not give: Thrombolytics for suspected dissection are out (see Tenecteplase). Nitroglycerin is not a preferred agent. It causes reflex tachycardia (see Nitroglycerin).
• Ruptured AAA (Paramedic/RN/CCT): the dissection targets above (HR 60–80, SBP below 120) and the beta-blocker and nicardipine regimens do not apply here. Place two large-bore IVs. Give blood and fluid per protocol, and limit crystalloid. Hypotensive (permissive) resuscitation with early blood products is commonly used. The vascular surgery team sets the target. Rapid transfer is the priority.

• Definitive imaging: CTA of the chest, abdomen and pelvis classifies the dissection, maps the branch vessels and shows the aortic root and coronary arteries before surgery.
• Stanford type A or suspected type A: emergency cardiothoracic surgery is the usual management. In IRAD, mortality was 26% for surgically managed type A. It was 58% for type A patients not operated on, typically because of age or comorbidity.
• Stanford type B, uncomplicated: treat medically with heart rate and BP control, then watch. Intervene for malperfusion, rupture, refractory pain or expansion. In IRAD, medically treated type B mortality was 10.7%.
• Infusion titration: run beta-blocker, nicardipine or clevidipine infusions through an arterial line. Titrate in steps to the target, checking BP at each one. The drug pages list the intervals.
• Ruptured AAA: emergency repair is endovascular or open, and the vascular team makes the call. In the IMPROVE randomised trial, 90-day mortality was similar either way. Between 3 months and 3 years, the endovascular strategy had fewer deaths (hazard ratio 0.57). Anatomy decides: endovascular when it is suitable, open when it is not.
• Blood and coagulation: massive transfusion and surgical bleeding control, per protocol. See Blood Transfusion and Hemorrhage Control.
• Hemodynamic monitoring: see Hemodynamic Monitoring.

• Destination: suspected type A goes to a cardiothoracic surgery center with an aortic team and an ICU. Suspected ruptured AAA goes to a vascular surgery center that can do endovascular and open repair and has a blood bank. Protocol and medical direction set the rule for the nearest facility.
• Time: Don't hold transfer to a surgical center to finish imaging at a facility that cannot operate. The receiving surgical team decides what imaging is needed where local systems allow it.
• In transit: continuous ECG and BP at protocol intervals, or an arterial line where present. In a stable patient, keep the beta-blocker or nicardipine infusion running on a pump with a titration plan. The heart rate target is 60–80 bpm, with SBP below 120 mmHg. If the patient turns hypotensive, stop titrating and follow the hypotension steps in ALS Management.
• Handoff: time and dose of every beta-blocker and vasoactive, pain medication, BP and HR trend, IV access sites, last oral intake, anticoagulant and antiplatelet use, and any PDE-5 inhibitor.
• Equipment and drugs: pumps, arterial line transducer, large-bore IV supplies, blood products per protocol, and labetalol and esmolol per the transport protocol.

• Pediatrics: The sources used here do not establish beta-blocker or nicardipine doses for children. Get pediatric cardiology or PICU guidance, and use weight-based dosing.
• Cocaine or stimulant-associated dissection: whether to give a beta-blocker is debated. Follow medical direction and the receiving team's plan.
• Pregnancy: a multidisciplinary team manages dissection in pregnancy, including maternal-fetal medicine and cardiology (2022 ACC/AHA guideline). Blood pressure control in pregnancy follows the obstetric protocol. For the obstetric labetalol regimen, see Labetalol.
• Genetic risk: Marfan and other connective-tissue disorders raise the risk. Genetic evaluation and family screening for aortic disease are part of the 2022 ACC/AHA guideline.
• Renal impairment: CTA contrast and volume shifts call for creatinine follow-up. No labeled dose change for the infusions on this page is established here.
• Patients on PDE-5 inhibitors or riociguat: Nitrates are contraindicated. Ask before any nitrate. See Nitroglycerin.

• Error: thrombolytic for presumed MI or stroke. A lytic given into a dissection can cause fatal hemorrhage. Dissection has to come up before every lytic decision. See Fibrinolytics.
• Error: beta-blocker or vasodilator in a hypotensive patient. Blocking the heart or dropping pressure in tamponade, rupture or shock can precipitate arrest. Treat the shock first. The dissection targets do not apply.
• Error: vasodilator before beta-blocker. Reflex tachycardia pushes shear stress up. In a stable patient, slow the heart first and only then lower the pressure.
• Error: nitrate in a patient on a PDE-5 inhibitor or riociguat. Together they cause severe hypotension, syncope or ischemia.
• Error: anchoring on ACS. A normal ECG and a troponin rise do not exclude dissection. Reconsider when pulses or BP differ.
• Error: BP taken in one arm only. A difference between the arms can be the only early sign. When stable, recheck both arms.
• Error: over-lowering BP. Push SBP below target while perfusion is poor, and you risk coronary and cerebral ischemia and organ injury. Use the lowest BP that keeps organs perfused.
• Error: nitroprusside without monitoring. Its boxed warning covers precipitous BP drops. It needs an arterial line and ICU-level monitoring. Use its label dilution and rate instructions (see DailyMed).