A 58-year-old man is evaluated in the emergency department for sudden-onset, severe "teari… — USMLE Step 2 CK

A 58-year-old man is evaluated in the emergency department for sudden-onset, severe "tearing" chest pain that radiates to his interscapular region. He is markedly anxious and diaphoretic. His blood pressure is $218/115\text{ mmHg}$ in the right arm and $182/95\text{ mmHg}$ in the left arm. His heart rate is $114\text{/min}$ . Physical examination reveals a new prominent early diastolic decrescendo murmur at the right upper sternal border. An electrocardiogram reveals sinus tachycardia and voltage criteria for left ventricular hypertrophy. Bedside chest radiography demonstrates a widened mediastinum. Arrange the following interventions in the most appropriate sequential order for the acute management of this patient.

1Administration of intravenous esmolol
2Administration of intravenous sodium nitroprusside
3Computed tomography (CT) angiography of the chest and abdomen
4Emergent median sternotomy and graft replacement

Answer

The correct sequence is to first administer intravenous esmolol, followed by intravenous sodium nitroprusside, then perform CT angiography, and finally proceed to emergent median sternotomy and graft replacement.

The precise sequential management of an acute aortic dissection is dictated by the physics of aortic wall stress. The initial goal is to minimize

dP/dt

(the rate of rise of ventricular pressure). This is achieved by administering a short-acting, titratable beta-blocker (esmolol) to lower the heart rate and blunt contractility. Only after the heart rate is controlled should an arterial vasodilator (sodium nitroprusside) be given to reduce systolic blood pressure to

<120\text{ mmHg}

. Once hemodynamically stabilized, the patient requires CT angiography to map the dissection. The presence of a new diastolic decrescendo murmur (aortic regurgitation) and right-to-left blood pressure discrepancy in this patient strongly suggests a Stanford Type A dissection involving the aortic root and arch vessels, mandating emergent surgical repair as the final, definitive step.

Step-by-Step Solution

Control heart rate and contractility.

Administer intravenous esmolol.

Initial medical therapy for acute aortic dissection requires decreasing aortic wall shear stress (

dP/dt

). A rapid-acting beta-blocker is the imperative first step.

Control systolic blood pressure.

Administer intravenous sodium nitroprusside.

Once heart rate is

<60\text{/min}

, a vasodilator is added to safely lower systolic blood pressure to

100\text{-}120\text{ mmHg}

without triggering reflex tachycardia.

Define the anatomical extent of the lesion.

Perform CT angiography of the chest and abdomen.

After hemodynamic stabilization, imaging is required to confirm the diagnosis and map branch vessel involvement for the surgical team.

Execute definitive management.

Transfer for emergent median sternotomy.

A Stanford Type A dissection (involving the ascending aorta, as evidenced by the new aortic regurgitation murmur) carries an exceptionally high mortality rate and requires immediate operative repair.

Key Concept

In the acute management of aortic dissection, beta-blockers must strictly be administered prior to vasodilators to prevent reflex tachycardia and increased aortic shear stress, followed by imaging and definitive surgical repair.

Estimated Time:1m 30s

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