USMLE Step 2 - Question 50

A 55 year old male with a history of hypertension presents to the emergency room with acute onset chest pains. His temperature is 37.0, blood pressure 190/70 in the left arm and 150/70 in the right arm, heart rate 110, respirations 22, and oxygen saturation 94% on room air. Physical examination reveals normal lung sounds, elevated jugular venous pressures and a II/IV early diastolic murmur at the right upper sternal border. ECG shows normal sinus rhythm and left ventricular hypertrophy. Which of the following is the most likely diagnosis?

A. Pulmonary embolus

B. Mitral valve stenosis

C. Aortic dissection

D. Ascending aortic aneurysm

E. Myocardial ischemia

Symptoms of aortic dissection include acute onset “tearing” chest pains that radiate to the upper back. Unlike symptoms of myocardial ischemia which slowly begin and worsen, aortic dissection pain peaks at its onset. Complications of aortic dissection include acute aortic valve regurgitation from aortic root dilation and failure of the aortic valve leaflets to coapt, cardiac tamponade from aortic root rupture causing a bloody pericardial effusion, shearing off of the right coronary artery resulting in inferior wall ST elevation myocardial infarction, and dissection up the carotid artery resulting in stroke. Hypertension is the number 1 risk factor for aortic dissection. When hypertensive during an aortic dissection the medication of choice to lower blood pressure is IV labetolol which reduces the shear force coming out the left venricle hitting the ascending aorta.