Tutor profile: Nayan S.

A 63 year old man with hypertension receives an echocardiogram that shows mild aortic stenosis and left ventricular dilation with an ejection fraction of 35%. He has been taking amlodipine for the past 3 years, and he has no symptoms and good exercise tolerance. His blood pressure is 132/78 mmHg, his pulse is 82/min, and oxygen saturation is 99%. What is the best next step in managing this patient's care? A. Initiate digoxin B. Initiate lisinopril C. Initiate low-dose diuretic D. Initiate spironolactone E. Reassure patient and follow up in 6 months.

The correct answer is B. Initiate lisinopril. Because the patient has an ejection of 35%, and normal ejection fraction is between 50-75%, he has left ventricular systolic dysfunction. Because he has no symptoms, this is defined as asymptomatic left ventricular systolic dysfunction, which is usually diagnosed after an abnormal ECG, murmur, or echocardiogram. The first step in managing asymptomatic left ventricular systolic dysfunction is starting an ACE inhibitor or angiotensin II receptor blocker to delay the onset of symptomatic heart failure and improve long-term cardiac function.

Increasing the substrate concentration overcomes the effect of inhibition in which reversible inhibitors? A. Competitive B. Uncompetitive C. Noncompetitive D. Both competitive and noncompetitive E. None of the above

The correct answer is competitive inhibitors (A). Competitive inhibitors bind to the active site of enzymes, competing with endogenous substrate. If you increase the substrate to high enough levels, it will outcompete the inhibitor for the active site. Uncompetitive and noncompetitive inhibitors bind sites away from the active site. Therefore, adding more substrate will not overcome the effects of these inhibitors.

A college professor presents to your office with weakness in her right hand and tingling on the front of her palm and right hand. She reports a recent increase in workload, requiring extended hours using her laptop. Based on the symptoms, which nerves could be affected and should be tested clinically?

The median and ulnar nerve. Both of these nerves innervate the palm of the hand, however the radial nerve primarily supplies the dorsal hand.