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MARFAN SYNDROME - Complete NEET PG Notes

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1. DEFINITION

• Skeletal abnormalities (tall stature, arachnodactyly)
• Cardiovascular defects (aortic root dilatation, dissection)
• Ocular changes (ectopia lentis)

OMIM: #154700

• Goldman-Cecil Medicine, p. 2749

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2. ETIOLOGY

Gene & Protein

Epidemiology

• Incidence: 1 in 3,000-5,000 births worldwide
• No ethnic or geographic predilection
• 70-85% are familial cases; 15-30% are de novo mutations (new germ cell mutations)
• Men tend to be more severely affected than women

Related Syndrome

• Marfan Syndrome Type 2 (MFS2): Caused by mutations in the TGF-beta type II receptor (TGFBR2) - clinically similar
• Loeys-Dietz Syndrome: Mutations in TGFBR1 or TGFBR2 - features generalized arterial tortuosity + susceptibility to dissection
• Homocystinuria: Must distinguish - similar Marfanoid features but autosomal recessive, causes mental retardation, hypercoagulability; treatable with Vitamin B6/folate/B12

• Robbins Pathology, p. 110 | Goldman-Cecil, p. 2749

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3. PATHOPHYSIOLOGY

Step 1 - Structural Defect

• Fibrillin-1 is the major structural component of 10-nm microfibrils in the extracellular matrix (ECM)
• Microfibrils are abundantly found in:
  • Aorta (provide tensile strength to vessel wall)
  • Ligaments
  • Ciliary zonules of the eye (support the lens)
• Mutant fibrillin-1 acts as a dominant negative - the abnormal protein incorporates into microfibrils and disrupts them

Step 2 - TGF-beta Dysregulation (KEY CONCEPT for MCQs)

• Normal microfibrils sequester (bind and inactivate) TGF-beta (via Latent TGF-beta Binding Proteins - LTBPs, which are homologous to fibrillin)
• Defective fibrillin → microfibrils cannot sequester TGF-beta → excessive (unregulated) TGF-beta signaling
• This excess TGF-beta signaling causes:
  • Bone overgrowth (skeletal features)
  • Mitral valve prolapse
  • Aortic dilatation
  • Abnormal lung septation (pneumothorax precursor)
  • Muscular hypoplasia

Step 3 - Cardiovascular Pathology (Aorta)

• Elastic fiber fragmentation + increased proteoglycans in tunica media = "Cystic Medial Necrosis" (CMN)
  • CMN is NOT specific to Marfan - also seen in hypertension and aging
• Weakened aortic wall → Aortic root/sinus of Valsalva dilatation → progressive aneurysm
• Aortic dissection usually begins just above the aortic valve (Type A) and can progress to the bifurcation
  • ~10% begin in descending thoracic aorta (Type B)
  • Retrograde dissection → hemopericardium → death

Step 4 - Ocular Pathology

• Ciliary zonule weakness (from deficient microfibrils) → Ectopia lentis (lens subluxation)
• Lens typically displaced superiorly (vs. homocystinuria where it displace inferiorly)

• Robbins Pathology, pp. 110-111 | Goldman-Cecil, p. 2749

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4. SIGNS (Objective Findings)

A. SKELETAL SIGNS (Most Visible)

B. CARDIOVASCULAR SIGNS

• Aortic root dilatation - begins in sinuses of Valsalva (most >80% of adults)
• Aortic regurgitation murmur - early diastolic, high-pitched at left sternal border
• Mitral valve prolapse - midsystolic click + late systolic murmur (~80% of patients)
• Mitral regurgitation murmur
• Wide pulse pressure (if significant AR)

C. OCULAR SIGNS

• Ectopia lentis - bilateral lens subluxation (superior displacement) - seen in 50-80%
• Flat corneas
• Myopia (most common ocular feature, >50%)
• Increased axial length of globe
• Retinal detachment risk

D. OTHER SIGNS

• Dural ectasia - dilatation of lumbosacral thecal sac, occurs in 90% of Marfan patients; major diagnostic criterion; causes widening of neuroforamina, lumbar radiculopathy
• Striae atrophicae (stretch marks) - over shoulders, breasts, lower back
• Spontaneous pneumothorax (~5%)
• Dolichocephaly (long narrow head)
• Enophthalmos, down-slanting palpebral fissures, malar hypoplasia, retrognathia (facial features)
• Sleep apnea
• Simple cysts in liver and kidneys

• Goldman-Cecil, p. 2750 | Firestein & Kelley's Rheumatology, p. 2343

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5. SYMPTOMS (Subjective Complaints)

• Tall stature - noted since childhood
• Visual disturbances - blurring, poor near/distance vision (myopia, astigmatism)
• Back pain - from scoliosis or dural ectasia causing lumbar radiculopathy
• Palpitations / Dyspnea - from mitral valve prolapse, arrhythmias, or progressive heart failure
• Chest pain - acute tearing/ripping chest pain radiating to the back = AORTIC DISSECTION (medical emergency)
• Shortness of breath - pneumothorax (sudden onset pleuritic chest pain + dyspnea)
• Joint pains - from hypermobility and scoliosis-related mechanical problems
• Fatigue - from cardiac dysfunction
• Headache / orthostatic symptoms - CSF leak from ectatic dura causing intracranial hypotension

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6. INVESTIGATIONS

A. Imaging (Most Important)

B. Genetic Testing

• FBN1 sequencing - identifies causative variant
• Used for presymptomatic diagnosis, prenatal diagnosis, and family testing
• Note: >1000 mutations described - testing alone is complex, so clinical diagnosis is primary

C. Revised Ghent Nosology (2010) - Diagnostic Criteria

Scenario 1: No family history of MFS

1. Aortic root Z-score ≥ 2 + Ectopia lentis (= definite Marfan)
2. Aortic root Z-score ≥ 2 + pathogenic FBN1 variant
3. Aortic root Z-score ≥ 2 + Systemic Score ≥ 7
4. Ectopia lentis + pathogenic FBN1 variant

Scenario 2: With family history of MFS

• Ectopia lentis alone
• Systemic score ≥ 7
• Aortic root Z-score ≥ 2 (adults ≥20 yr) or ≥ 3 (<20 yr)

Systemic Score Table (Revised Ghent)

• Firestein & Kelley's Rheumatology, p. 2342-2343 | Tietz Laboratory Medicine, p. 170

D. Other Lab Tests

• Plasma homocysteine - to exclude homocystinuria (key differential)
• Urine amino acids - elevated methionine in homocystinuria
• Echocardiography - essential for follow-up (annually)

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7. TREATMENT

A. Medical Management (Drugs)

1. Beta-Blockers (FIRST-LINE, most important)

• Drug of choice: Propranolol or Atenolol
• Mechanism: Reduce heart rate and dP/dt (force of ventricular contraction) → decrease hemodynamic stress on the aortic wall
• Goal: Prevent/slow aortic root dilatation and reduce risk of dissection
• Dose: Atenolol 25-100 mg/day; Propranolol 20-80 mg 2-4 times daily (titrated to HR and aortic dimensions)
• Route: Oral
• Evidence: Started as soon as diagnosis is established; continued lifelong

2. Angiotensin Receptor Blockers (ARBs) - (Emerging evidence, now used)

• Drug: Losartan (most studied)
• Mechanism: Block TGF-beta signaling via angiotensin receptor type II pathway → slow aortic dilation
• Dose: Losartan 50-100 mg/day orally
• Route: Oral
• Role: Used in patients intolerant to beta-blockers OR in combination with beta-blockers
• Evidence: Several RCTs have shown benefit in slowing aortic root growth, especially in children/adolescents

3. ACE Inhibitors

• Alternative to ARBs, similar TGF-beta pathway attenuation
• Less commonly used as first-choice compared to ARBs

Summary Drug Table

B. Surgical Management (KEY for MCQs)

Indications for Elective Aortic Root Surgery

• Aortic root diameter ≥ 5.0 cm (most guidelines)
• Rate of expansion > 1 cm/year regardless of size
• Moderate-to-severe aortic regurgitation
• Family history of dissection at smaller diameters (some use 4.5 cm threshold)
• Before or during pregnancy if root is enlarging

Surgical Options

1. Bentall Procedure - composite valve-graft replacement (most common) - replaces aortic root + valve
2. Valve-sparing aortic root replacement (David or Yacoub procedure) - preserves native aortic valve; preferred in young patients

Mitral Valve Surgery

• Indicated for severe symptomatic mitral regurgitation
• Repair preferred over replacement when possible

Scoliosis Surgery

• Spinal fusion when curves >40-50 degrees or progressive

C. Activity Restrictions

• Avoid strenuous isometric exercises (weight lifting, heavy resistance training) - increases aortic wall stress
• Avoid contact sports (basketball, football, martial arts)
• Competitive sports are generally contraindicated for patients with significant aortic enlargement
• Moderate aerobic exercise (walking, swimming) is permitted

D. Monitoring Protocol

• Annual echocardiography for aortic root surveillance
• Ophthalmologic exam annually (especially in children)
• Slit-lamp exam for lens assessment
• MRI for dural ectasia if back pain/radiculopathy develops
• Genetic counseling - AD inheritance, 50% chance of passing to offspring

E. Special Situations

Pregnancy

• High-risk situation - aortic dissection risk is significantly elevated during pregnancy
• Aortic root >4.5 cm is a relative contraindication to pregnancy
• Beta-blockers continued throughout pregnancy
• Mode of delivery: Caesarean section preferred if aortic root >4.5 cm or rapidly enlarging
• Avoid Valsalva maneuver (pushing in labor) if aortic root is enlarged

Antibiotic Prophylaxis

• For dental/surgical procedures if prosthetic heart valves are present (follows standard infective endocarditis prophylaxis guidelines)

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8. COMPLICATIONS

• Primary: Aortic dissection/rupture (retrograde → hemopericardium)
• Secondary: Heart failure (from valvular regurgitation)
• Without treatment, many patients die before 30-40 years of age
• With appropriate management, life expectancy approximates that of the general population

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9. IMPORTANT HIGH-YIELD POINTS FOR NEET PG (MCQ TRAPS)

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10. DIFFERENTIAL DIAGNOSIS

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Sources Used:

• Goldman-Cecil Medicine International Edition, Chapter 239 (Marfan Syndrome), pp. 2748-2751
• Robbins & Kumar Basic Pathology, pp. 110-111 (Genetic Disorders chapter)
• Firestein & Kelley's Textbook of Rheumatology, Chapter 107, pp. 2342-2344
• Bradley & Daroff's Neurology in Clinical Practice, Chapter 104
• Tietz Textbook of Laboratory Medicine, 7th Ed., pp. 165-184
• Thompson & Thompson Genetics and Genomics in Medicine, 9th Ed.

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Clinical Interpretation - Dhiraj Lande, 23 Years

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REPORT 1: 2D ECHOCARDIOGRAPHY

Finding-by-Finding Breakdown

Echo Conclusion

Important for the Marfan context: Notably, the echo does not report aortic root dimensions (diameter at sinus of Valsalva). In a patient with suspected or known Marfan syndrome, this is a critical measurement. If aortic root diameter was not specifically measured and reported, a repeat echo with specific measurement of aortic root Z-score should be requested.

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REPORT 2: ECG (12-Lead)

ECG Parameters

Automated ECG Interpretation

1. Sinus Bradycardia with Sinus Arrhythmia
2. Prolonged P-wave
3. 1st-degree AV Block
4. Positive T-wave in V1

Manual Interpretation of Each Finding

1. Sinus Bradycardia with Sinus Arrhythmia

• HR is 80 bpm - this is actually NOT bradycardia (bradycardia = HR <60 bpm)
• The machine's "sinus bradycardia" label at 80 bpm is likely a machine error or borderline interpretation artifact
• Sinus arrhythmia = slight variation in RR intervals with breathing - completely normal and physiological, especially in young adults and athletes

2. Prolonged P-wave (103 ms)

• Normal P-wave duration is up to 120 ms
• 103 ms is within normal limits - the machine's "prolonged" flag is borderline
• Could indicate mild left atrial enlargement or intra-atrial conduction delay if truly prolonged, but 103 ms is not clinically significant

3. 1st-Degree AV Block

• PR interval = 145 ms - this is within normal limits (120-200 ms)
• 1st-degree AV block is diagnosed at PR > 200 ms
• The machine's interpretation of "1st-degree AV block" appears to be incorrect at this value - the PR of 145 ms is normal
• Clinically, this is NOT a 1st-degree AV block

4. Positive T-wave in V1

• Normally, T-waves in V1 are negative or flat
• A positive T-wave in V1 can be a normal variant in young people, OR
• Can indicate right ventricular strain, posterior MI, or RBBB pattern - but given the normal echo and other parameters, this is likely a normal variant in this 23-year-old

ECG Conclusion

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WHY IS PAIN RETURNING AFTER BETA-BLOCKER COURSE?

1. Beta-Blockers Were Stopped (Most Likely Reason)

• In Marfan syndrome, beta-blockers (e.g., Atenolol/Propranolol) are NOT a short 1-month course
• They are lifelong, continuous therapy to protect the aorta from progressive dilatation
• Stopping them causes:
  • Return of elevated heart rate and dP/dt (force of contraction)
  • Increased hemodynamic stress on the aortic wall
  • Return of palpitations, chest discomfort, and atypical chest pain

2. Inadequate Dose

• If the dose was too low, the aortic protection was insufficient
• Target is to keep resting HR around 55-65 bpm

3. Pain May Be Non-Cardiac

• Musculoskeletal pain is very common in Marfan syndrome due to scoliosis, joint laxity, and ligamentous hypermobility
• Beta-blockers do not treat this type of pain
• This pain would persist or return regardless of cardiac medications

4. Dural Ectasia

• If pain is in the lower back / radiating to legs, this could be from dural ectasia (present in 90% of Marfan patients)
• Beta-blockers have no effect on dural ectasia pain
• Requires MRI lumbosacral spine for diagnosis

5. Mitral Valve Prolapse Syndrome

• Even with a "normal" mitral valve on this echo, MVP can cause atypical chest pain, palpitations, and anxiety-related symptoms
• These can persist even with beta-blockers if dose is subtherapeutic

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KEY ACTION POINTS FOR DHIRAJ

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Disclaimer: This is an educational interpretation for a medical student. All clinical decisions must be made by the treating physician who has full access to the patient's clinical history, examination, and all investigations. The patient should return to their cardiologist for reassessment, specifically to discuss whether beta-blockers should be continued, the dose needs adjustment, and whether aortic root dimensions have been properly assessed.