Cardiovascular · Year 1 · from Cardiovascular
Case 3: Coarctation of the Aorta - Differential Blood Pressure
Clinical Image
Source: Wikimedia Commons - Aortic coarctation - CC BY-SA 3.0
Patient Presentation
A 16-year-old male is referred to cardiology after being found to have hypertension during a sports physical. He has no symptoms but his mother recalls he was a "poor feeder" as an infant and had frequent nosebleeds as a child. He is an active soccer player but admits to occasional leg fatigue with running.
Demographics
- Age: 16 years
- Sex: Male
- Past Medical History: "Heart murmur" noted as infant, no follow-up
- Family History: Mother has a bicuspid aortic valve
Chief Complaint
Hypertension discovered on routine sports physical
Physical Examination
- Right arm blood pressure: 162/88 mmHg
- Left arm blood pressure: 158/86 mmHg
- Right leg blood pressure: 110/78 mmHg
- Heart rate: 72 bpm
- General: Well-developed, muscular teenager
- Cardiovascular: Grade 2/6 systolic ejection murmur at left upper sternal border, systolic murmur between scapulae posteriorly
- Peripheral pulses: Strong radial pulses bilaterally, weak femoral pulses with radio-femoral delay
- Extremities: Well-developed upper body, leg muscles somewhat less developed
Workup
- Chest X-ray: "3" sign (indentation at coarctation with pre- and post-stenotic dilation), rib notching (inferior surface of ribs 3-8)
- ECG: Left ventricular hypertrophy
- Echocardiography: Bicuspid aortic valve, discrete coarctation distal to left subclavian artery with gradient of 45 mmHg
- CT angiography: Discrete coarctation with well-developed intercostal collaterals
- Ankle-brachial index: Abnormal (0.68)
Diagnosis
Coarctation of the Aorta with Associated Bicuspid Aortic Valve
Treatment
- Beta-blocker for blood pressure control pending intervention
- Intervention options:
- Balloon angioplasty with stent placement (preferred for discrete coarctation in adolescents/adults)
- Surgical repair if complex anatomy
- Long-term surveillance for:
- Recoarctation
- Bicuspid aortic valve complications (stenosis, regurgitation, aortopathy)
- Cerebral aneurysms (increased risk)
- Persistent hypertension despite repair
- Endocarditis prophylaxis counseling
Physiological Principles Demonstrated
- Differential blood pressure: The hallmark finding is upper extremity hypertension with lower extremity hypotension. Blood pressure proximal to the coarctation is elevated; distal pressure is reduced.
- Collateral circulation development: Chronic obstruction leads to development of collateral vessels through intercostal and internal mammary arteries, which erode the undersurface of ribs (rib notching) and cause the posterior systolic murmur.
- Associated anomalies: Coarctation is strongly associated with bicuspid aortic valve (50-80% of cases) and Turner syndrome in females.
- Hypertension mechanism: Upper body hypertension results from mechanical obstruction and activation of the renin-angiotensin system due to reduced renal perfusion. Hypertension may persist after repair due to vascular remodeling.