Aortic Dissection and Acute Aortic Syndromes

25.1Classification and immediate risk stratification

The initial clinical priority in suspected acute aortic syndrome is rapid classification. Abrupt severe chest, back, or abdominal pain remains the common entry point, but the risk signal is stronger when pain is accompanied by a pulse or pressure deficit, a new aortic-regurgitation murmur, focal neurological signs, syncope, renal or visceral ischemia, or asymmetric limb perfusion. In that setting, diagnostic delay is more dangerous than over-triage. Computed tomography angiography of the chest and abdomen is the usual confirmatory study because it defines the intimal flap, true and false lumens, branch-vessel involvement, rupture signs, and the proximal and distal extent of disease in a single examination; transthoracic and especially transoesophageal echocardiography are bedside alternatives when the patient is too unstable for CT or when the ascending aorta and valve must be assessed immediately ACC/AHA 2022 · ESC 2014 · ACC/AHA 2010.

The Stanford classification is the first branch point because it determines disposition. Any dissection involving the ascending aorta is Stanford type A and is treated as an emergency surgical disease; a dissection that originates distal to the left subclavian artery without ascending involvement is Stanford type B, and the uncomplicated type B patient is first stabilised medically ACC/AHA 2022 · ESC 2014 · International Registry Acute 2000. DeBakey terminology adds anatomic extent—ascending and descending involvement, ascending-only disease, and descending disease with variable distal extension—so it remains useful for operative description, but it does not replace the Stanford branch when the emergency decision is being made. Contemporary type B reporting standards add the language that matters for vascular planning: acute, subacute, or chronic timing; uncomplicated versus complicated presentation; entry-tear location; false-lumen status; and branch-vessel consequences Society Vascular Surgery 2020.

Risk stratification should be performed while the classification is being assigned, not after the report is filed. For type A disease, the dangerous associated problems are tamponade, severe aortic regurgitation, coronary involvement, neurological injury, and malperfusion. For type B disease, the key question is whether the patient is truly uncomplicated: persistent pain, refractory hypertension, rupture, rapidly changing diameter, or renal, visceral, spinal, or limb malperfusion moves the patient out of the medical-only pathway and into an aortic-intervention discussion ACC/AHA 2022 · Society Vascular Surgery 2020. The clinical pathway is time-critical: suspect the diagnosis, image the entire relevant aorta, assign the Stanford type, and determine whether the patient requires the operating theatre, intensive care, or an endovascular suite.

25.2Immediate medical therapy

Medical treatment begins as soon as acute dissection is suspected strongly enough to trigger aortic imaging, because every minute of uncontrolled impulse pressure increases the chance of propagation while the definitive branch decision is being made. The primary therapeutic target is the reduction of aortic wall shear stress, rather than blood pressure alone. Intravenous beta-blockade is therefore the initial drug class, with society guidance commonly aiming for a heart rate near 60 beats per minute and systolic pressure near 100–120 mmHg when end-organ perfusion tolerates that range ACC/AHA 2022 · Editor's Choice Management 2017 · ESC 2014 · Beta Blockers 2025. This order matters. A vasodilator can lower the number on the monitor, but if it is given before rate control it may provoke reflex tachycardia and increase dP/dt, which is the physiologic error the treatment is meant to prevent.

Once rate control is established, persistent hypertension is treated by adding a titratable intravenous vasodilator such as nicardipine or clevidipine. The target should be treated as a hemodynamic range rather than a rigid number: mental status, urine output, lactate trend, limb perfusion, pulse examination, and abdominal findings determine whether the lower pressure limit is safe. In a patient with suspected malperfusion, excessive pressure reduction can worsen organ flow, so the goal is the lowest pressure that maintains perfusion while the aortic team decides whether the problem is type A disease, complicated type B disease, or uncomplicated type B disease ACC/AHA 2022 · ESC 2014.

This immediate phase is also a coordination problem. Monitoring, analgesia, blood-pressure titration, and rapid communication with the receiving aortic service all support the same physiologic aim: prevent extension, rupture, and end-organ loss while definitive treatment is being arranged. Medical control is not a substitute for operation in type A dissection or for TEVAR in complicated type B dissection; it is the stabilising bridge that allows the correct pathway to occur under controlled conditions.

25.3Stanford type A: emergency surgery

Stanford type A dissection is an emergency because the ascending aorta, aortic root, valve, pericardium, coronary ostia, and arch vessels may all be threatened at once. The correct response is immediate aortic-surgery mobilization and transfer to an experienced center when definitive repair is not available locally; additional non-aortic testing should not delay transfer when the imaging or clinical probability is high ACC/AHA 2022 · Insights From International 2018 · International Registry Acute 2000. The aim of early medical therapy during transfer is to reduce shear without obscuring deterioration: falling pressure, recurrent syncope, new neurological deficit, worsening hypoxaemia, chest pain that will not settle, or loss of pulses should be treated as possible progression rather than as routine transport physiology.

The operation is an anatomic rescue that extends beyond simple replacement of the visible flap. At minimum, the ascending aorta is replaced and the proximal tear is controlled when feasible; root, valve, coronary, hemiarch, or arch work is added according to the entry tear, aortic-regurgitation mechanism, connective-tissue phenotype, arch involvement, and the patient’s physiologic reserve. Registry and contemporary surgical series consistently show that type A dissection carries high early mortality, that survival depends on rapid operative management, and that outcomes have improved across the IRAD era as diagnosis, transfer, operative technique, and perioperative care have matured Current Outcome after 2023 · Insights From International 2018 · International Registry Acute 2000.

The center decision matters because type A repair is rarely a single-technical-step operation. Cerebral protection, myocardial protection, management of malperfusion, bleeding control, and postoperative critical care all affect outcome, and center-volume analyses and IRAD reports support regionalised care for patients who can be moved safely Management acute type 2022 · Prediction prognosis reintubation 2022 · Insights From International 2018. Very elderly patients, patients presenting with coma or severe malperfusion, and those with prohibitive comorbidity require individualised judgment, but the default remains urgent open repair rather than prolonged medical treatment. Endovascular approaches for selected type A scenarios are reported, but they remain exceptional and should not dilute the emergency open-repair pathway for the usual patient with ascending involvement ACC/AHA 2022 · Current status challenges 2023.

25.4Uncomplicated type B: medical therapy and the TEVAR question

The uncomplicated type B patient is the patient in whom the descending dissection is dangerous but not yet declaring rupture, malperfusion, uncontrolled symptoms, or rapid enlargement. In that setting, the acute treatment is optimal medical therapy: heart-rate and pressure control, close clinical examination, and interval imaging to confirm that the aorta is not enlarging and that branch-vessel perfusion remains intact ACC/AHA 2022 · Society Vascular Surgery 2020. This default is important for trainees because the presence of a dramatic dissection flap on CT is not, by itself, an indication for immediate stent-graft placement. The decision is made from the clinical state, the anatomy, the time from presentation, and the predicted risk of late aneurysmal degeneration.

The role of TEVAR in uncomplicated type B dissection is primarily a question of timing. The INSTEAD trial compared TEVAR plus optimal medical therapy with optimal medical therapy alone in stable uncomplicated type B dissection and did not show an early aortic-related mortality advantage at 2 years; the extended INSTEAD-XL follow-up showed lower aortic-specific mortality and less disease progression at 5 years in the TEVAR group Endovascular repair type 2013 · Randomized comparison strategies 2009. That result supports the concept that favorable remodelling can matter over time, but it should not be read as proof that every acute uncomplicated patient should undergo immediate TEVAR. The enrolled populations were stable subacute or chronic patients, and the benefit signal is strongest when the anatomy is suitable and the procedural risk is low.

In contemporary practice, early TEVAR is considered selectively in the subacute window when the anatomy suggests high late risk: a large total aortic diameter, a large false lumen, partial false-lumen thrombosis, a dominant proximal entry tear, or a proximal landing zone that permits durable coverage without unacceptable arch or spinal risk ACC/AHA 2022 · Initial Thoracic Endovascular 2023 · Mid- long-term outcomes 2022 · Thoracic endovascular aortic 2016. Uncomplicated acute type B dissection usually starts with medical therapy, progressing to elective or semi-elective TEVAR only when the patient’s anatomy, remodelling behavior, and operative risk make late aortic benefit plausible.

25.5Complicated type B: TEVAR

Complicated type B dissection is defined by the failure of the aorta to behave safely under medical therapy, rather than by the length of the flap. Malperfusion of the visceral, renal, lower-limb, or spinal circulation; contained rupture; refractory pain; refractory hypertension; or rapid expansion on serial imaging should be treated as an intervention indication rather than as a reason to intensify observation ACC/AHA 2022 · Society Vascular Surgery 2020. Arch involvement, entry-tear position, and branch-vessel anatomy refine the plan, because proximal seal and preservation of critical branch flow determine whether TEVAR alone is enough or whether adjunctive fenestration, branch stenting, or staged repair will be needed Acute type B 2007 · Thoracic endovascular aneurysm 2011.

The procedural objective is sequential. First, cover the dominant proximal entry tear when there is an adequate landing zone. Second, expand the true lumen so that dynamic malperfusion improves. Third, promote false-lumen thrombosis and favorable aortic remodelling while avoiding new injury at the proximal and distal edges of the repair. TEVAR has become the default operation for suitable complicated acute type B dissection because it directly addresses the entry tear and true-lumen compression without the physiologic insult of open descending thoracic replacement Endovascular treatment complicated 2023 · Thoracic endovascular aneurysm 2011. The technical plan should still be individualised: coverage near the left subclavian artery, extensive thoracic coverage, renal or visceral branch compromise, and chronic dissection membranes all change the risk profile and the need for adjunctive procedures Thoracic Endovascular Aortic 2022.

Registry and comparative analyses report lower aortic-specific mortality and better remodelling with TEVAR than with medical therapy alone in complicated or high-risk type B disease, but selection bias, center experience, and inconsistent definitions of “complicated” influence the size of the effect Endovascular treatment complicated 2023 · Initial Thoracic Endovascular 2023 · Mid- long-term outcomes 2022. Open repair is now reserved for patients whose anatomy, access, rupture pattern, or end-organ disease cannot be managed endovascularly. The clinical question is whether proximal entry-tear coverage will restore perfusion or prevent rupture more safely than continued medical therapy.

25.6Long-term outpatient management

A patient who survives the acute episode has not been cured of aortic disease. Long-term management is built around two linked goals: keep impulse pressure low enough to reduce late aortic events, and detect adverse remodelling before rupture, malperfusion, or aneurysmal degeneration forces an emergency return. Beta-blockade is the pharmacologic foundation for chronic dissection follow-up, with current society guidance and contemporary observational analyses supporting long-term use to reduce aortic-related events when it is tolerated ACC/AHA 2022 · ESC 2014 · Beta Blockers 2025. The physiologic logic of the acute phase applies longitudinally: the goal is a sustained reduction in heart rate, systolic pressure, and shear stress during daily activity.

Most patients need more than one drug. If blood pressure remains above target on beta-blockade, an angiotensin receptor blocker or ACE inhibitor is layered, with angiotensin receptor blockade particularly attractive when a genetic aortopathy such as Marfan or a related syndrome is part of the phenotype ACC/AHA 2022 · ESC 2014. Drug choice is then shaped by renal function, bradycardia, frailty, concomitant coronary disease, and tolerance. The outpatient visit should explicitly check adherence and home measurements, because late aortic enlargement often reflects months of poor pressure control rather than a single missed scan.

Lifestyle counseling should be concrete. Smoking cessation, weight management, and avoidance of high-intensity isometric exertion or competitive contact sport reduce recurrent hemodynamic stress and the competing cardiovascular risk that many dissection patients carry. Statin therapy is considered against the patient’s broader cardiovascular comorbidity rather than prescribed simply because a flap exists. Long-term care therefore belongs to an aortic clinic model: medication titration, surveillance imaging, symptom education, and rapid re-entry to specialist care when pain, pulse change, neurological symptoms, or limb or visceral ischemia recurs ACC/AHA 2022 · Current Outcome after 2023.

25.7Post-acute imaging surveillance

Surveillance is the safety net that prevents chronic dissection from becoming an unplanned rupture or malperfusion admission. After acute aortic syndrome, cross-sectional imaging is generally organized at 1 month, 6 months, and 12 months, and then annually when the aorta is stable ACC/AHA 2022 · Editor's Choice Management 2017 · ESC 2014 · Insights From International 2018. Computed tomography angiography is the usual modality because it shows diameter, true-lumen caliber, false-lumen patency, branch-vessel involvement, entry tears, rupture signs, and stent-graft position after TEVAR. Magnetic resonance angiography is used in selected patients to reduce cumulative iodinated contrast and ionising radiation, especially in younger patients who face lifelong imaging.

The scan should be interpreted as a comprehensive management tool rather than a simple diameter report. The clinician should compare the same aortic segments over time, record false-lumen thrombosis or persistent flow, note true-lumen collapse or recovery, reassess visceral, renal, spinal, and limb perfusion, and identify new tears or stent-graft edge problems after TEVAR. Stable or shrinking diameter with favorable false-lumen thrombosis supports movement toward the annual cadence; persistent false-lumen pressurisation, interval growth, a new entry tear, or recurrent branch-vessel compromise should shorten the interval and open a re-intervention discussion at that visit ACC/AHA 2022 · Insights From International 2018 · Society Vascular Surgery 2020.

The surveillance plan also has to match the original treatment. A medically managed uncomplicated type B dissection is watched for late aneurysmal degeneration and changing false-lumen behavior. A TEVAR-treated patient is watched for remodelling, endoleak, distal stent-induced injury, progressive distal dissection, and access-vessel sequelae. A repaired type A patient may still have residual arch or descending dissection that requires the same disciplined follow-up as primary type B disease. Surveillance intervals can be extended only when the aorta demonstrates stability; they must be shortened immediately if symptoms, diameter growth, malperfusion, or adverse remodelling appear ACC/AHA 2022 · Editor's Choice Management 2017 · ESC 2014.