A 68-year-old woman is brought to the emergency department via ambulance due to the sudden… — USMLE Step 2 CK

A 68-year-old woman is brought to the emergency department via ambulance due to the sudden onset of severe, "tearing" chest pain that radiates to between her shoulder blades. The pain started $45$ minutes ago while she was watching television. She has a history of poorly controlled essential hypertension and tobacco use. On arrival, she is visibly diaphoretic and in acute distress. Her blood pressure is $210/115 \text{ mm Hg}$ in the right arm and $175/95 \text{ mm Hg}$ in the left arm. Her heart rate is $112/\text{min}$ , and her respiratory rate is $22/\text{min}$ . Oxygen saturation is $96\%$ on room air. Physical examination reveals a new early diastolic decrescendo murmur auscultated best at the right upper sternal border. Neurologic examination is unremarkable. Two large-bore intravenous lines are established.

Arrange the following steps in the most appropriate chronological order for the evaluation and management of this patient.

1Perform a 12-lead electrocardiogram (ECG) to assess for acute myocardial ischemia
2Initiate intravenous esmolol to decrease heart rate and wall shear stress
3Add intravenous sodium nitroprusside to strictly control systolic blood pressure
4Obtain urgent computed tomography (CT) angiography of the aorta
5Consult cardiothoracic surgery for emergent ascending aorta replacement

Answer

The correct chronological sequence for managing this patient is: (1) Perform a 12-lead ECG, (2) Initiate intravenous esmolol, (3) Add intravenous sodium nitroprusside, (4) Obtain a CT angiogram of the aorta, and (5) Consult cardiothoracic surgery.

The correct sequence prioritizes rapid life-threat triage (ECG), followed by immediate empirical hemodynamic stabilization (beta-blocker first to lower heart rate and

dP/dt

, then vasodilator to lower blood pressure). Once the patient's hemodynamics are medically controlled, definitive imaging (CT angiography) is safely obtained to map the anatomy, which is necessary before cardiothoracic surgery can perform a targeted operative repair for a Type A dissection.

Step-by-Step Solution

Recognize the clinical presentation as highly suspicious for an acute aortic dissection.

The patient has tearing chest pain radiating to the back, an asymmetric blood pressure presentation, and a new murmur of aortic regurgitation.

This constellation of findings is the classic triad for a Stanford Type A aortic dissection.

Determine the immediate triage action for any patient presenting with severe acute chest pain.

A 12-lead ECG must be performed first.

Regardless of the suspected diagnosis, acute coronary syndrome must be rapidly evaluated and ruled in or out, as it dictates immediate life-saving pathways and can sometimes co-occur with or mimic dissection.

Determine the first step in medical stabilization for a suspected aortic dissection.

Intravenous beta-blockers (esmolol) are initiated.

Reducing the heart rate and the force of left ventricular contraction (wall shear stress,

dP/dt

) is the most critical medical intervention to prevent propagation of the dissection flap.

Determine the secondary step in medical stabilization for refractory hypertension.

Intravenous vasodilators (sodium nitroprusside) are added.

Vasodilators lower the sheer mechanical pressure on the aorta but must strictly follow beta-blockade to prevent reflex sympathetic tachycardia, which would paradoxically increase shear stress.

Determine the appropriate diagnostic imaging modality for a hemodynamically stable patient.

CT angiography of the aorta is performed.

While medical therapy is started empirically, definitive diagnosis and anatomical mapping require imaging. CT angiography is preferred in stable patients without renal failure.

Determine the definitive management based on the likely anatomic involvement.

Emergent cardiothoracic surgical consultation is obtained.

Stanford Type A dissections (involving the ascending aorta) carry a high risk of fatal complications like cardiac tamponade or free rupture, requiring urgent surgical replacement.

Key Concept

The management of suspected acute aortic dissection follows a strict sequence: initial ECG triage, empirical anti-impulse therapy (beta-blockers strictly BEFORE vasodilators), definitive imaging (CT angiography in stable patients), and surgical consultation for Type A involvement.

Estimated Time:2m 0s

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