Marfan Syndrome — Arachnodactyly and Wrist/Thumb Signs
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stethoscope Medicine
A 19-year-old man presents to the cardiology clinic for evaluation of a new early diastolic murmur detected on routine sports screening. He is noted to be unusually tall and thin with long, slender fingers. On examination, when he flexes his thumb into a closed fist, the tip of the thumb protrudes beyond the ulnar border of his hand—the structure marked **B** in the diagram. His father died suddenly at age 39 from suspected aortic dissection. Slit-lamp examination reveals bilateral superotemporal ectopia lentis, and echocardiography shows aortic root dilatation (5.1 cm, Z-score > 3) with aortic regurgitation and mitral valve prolapse. Which of the following is the most appropriate next step in management of this patient?
A. Prescribe high-dose aspirin and refer for ophthalmologic surgery to correct the lens dislocation
B. Perform immediate aortic root replacement surgery before any further cardiac testing
C. Initiate penicillin prophylaxis and schedule routine follow-up echocardiography in 2 years
D. Initiate beta-blockers or losartan to reduce dP/dt and slow aortic root dilatation; refer for cardiothoracic surgery consultation and restrict competitive sports
Explanation
Why option 1 is correct
The positive Steinberg thumb sign (structure B) is a highly characteristic hand finding in Marfan syndrome and, combined with ectopia lentis and aortic root dilatation, confirms the diagnosis. According to Braunwald's Heart Disease (12th Edition, Chapter 92), the management of Marfan syndrome with aortic root involvement includes: (1) beta-blockers or losartan (an ARB) to reduce dP/dt and slow aortic root dilatation, (2) cardiothoracic surgery consultation for elective aortic root replacement when the root diameter reaches 5.0 cm (or smaller if there is a family history of dissection or rapid progression), and (3) avoidance of competitive, contact, and isometric sports. This patient's aortic root is already 5.1 cm with a family history of sudden death from suspected aortic dissection, making him a high-risk candidate for elective surgery. Medical therapy and close monitoring are the immediate priorities.
Why each distractor is wrong
Option 2: Immediate aortic root replacement is not the standard first step. Elective surgery is indicated when the aortic root reaches 5.0 cm, but medical optimization with beta-blockers or losartan is initiated concurrently, and the timing of surgery is individualized based on risk factors, rate of progression, and surgical candidacy. Emergency surgery is reserved for acute dissection or rupture.
Option 3: High-dose aspirin is not indicated for Marfan syndrome and does not address the underlying pathophysiology of aortic root dilatation. Ophthalmologic surgery for ectopia lentis is not an urgent priority in the acute management of aortic root disease; the lens dislocation is managed conservatively unless it causes significant visual impairment. The cardiac manifestations take precedence.
Option 4: Penicillin prophylaxis is indicated for rheumatic heart disease or endocarditis risk, not Marfan syndrome. A 2-year interval for follow-up echocardiography is far too long in a patient with significant aortic root dilatation (5.1 cm) and a family history of sudden cardiac death; more frequent monitoring (typically every 6–12 months) is required to detect rapid progression.
High-YieldNEET PG
The positive Steinberg thumb sign is a hallmark of Marfan syndrome; when combined with ectopia lentis and aortic root dilatation, it confirms the diagnosis and mandates aggressive cardiac management with beta-blockers/losartan, surgical consultation, and sports restriction to prevent sudden cardiac death.
Braunwald's Heart Disease, 12th Edition, Chapter 92: The Marfan Syndrome and Other Heritable Disorders of Connective Tissue
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