A 65-year-old man is brought to the emergency department due to the sudden onset of severe… — USMLE Step 2 CK

A $65$ -year-old man is brought to the emergency department due to the sudden onset of severe, tearing chest pain that radiates to his back. His temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure is $210/120\text{ mmHg}$ in the right arm and $170/95\text{ mmHg}$ in the left arm, pulse is $112/\text{min}$ , and respirations are $20/\text{min}$ . Physical examination reveals a new diastolic decrescendo murmur at the right upper sternal border. A portable chest radiograph shows a widened mediastinum. Acute ascending aortic dissection is strongly suspected. Arrange the following steps in the most appropriate chronological sequence for the management of this patient.

1Administer intravenous esmolol
2Administer intravenous sodium nitroprusside
3Obtain computed tomography (CT) angiography of the chest
4Proceed with emergent surgical repair

Answer

The correct management sequence is to first administer intravenous esmolol, followed by intravenous sodium nitroprusside, then obtain CT angiography of the chest, and finally proceed with emergent surgical repair.

The proper sequence for managing a hemodynamically stable (but hypertensive) patient with an acute aortic dissection is initial strict blood pressure and heart rate control, followed by diagnostic confirmation, and finally definitive surgical repair for Type A dissections. Beta-blockers (esmolol) MUST be given before vasodilators (nitroprusside) to prevent reflex tachycardia and increased ventricular contractility, both of which increase aortic wall shear stress. Once the patient is medically stabilized, CT angiography is performed to confirm the anatomy. Because this patient has a Type A dissection (indicated by the aortic regurgitation murmur and right-to-left arm pulse/pressure deficits from brachiocephalic involvement), surgery is the ultimate destination.

Step-by-Step Solution

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

The patient exhibits tearing chest pain, asymmetric blood pressures, a widened mediastinum, and a new murmur of aortic regurgitation.

Recognizing the life-threatening nature of the emergency dictates immediate initial stabilization rather than delaying for imaging.

Select the first-line pharmacologic stabilization.

Administer an intravenous beta-blocker (esmolol).

Beta-blockade reduces heart rate and left ventricular contractility, thereby reducing aortic wall shear stress (

dP/dt

) and preventing dissection propagation.

Select the second-line pharmacologic stabilization.

Administer an intravenous vasodilator (sodium nitroprusside).

A vasodilator is often necessary to further reduce blood pressure but must strictly follow beta-blockade to prevent compensatory reflex tachycardia.

Choose the definitive diagnostic step.

Obtain a CT angiography of the chest.

Definitive imaging is required to confirm the diagnosis and classify the dissection before taking the patient to the operating room.

Choose the definitive therapeutic step.

Proceed with emergent cardiothoracic surgery.

Stanford Type A dissections carry a very high mortality rate and require immediate surgical intervention for repair.

Key Concept

The precise sequence of anti-impulse therapy and definitive management in acute aortic dissection.

Estimated Time:1m 30s

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