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Common Congenital Heart Lesions - page 10 / 126





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2. Transposition of the Great Arteries

Clinical Presentation: neonate presents on first day of life with cyanosis that increases as ductus arteriosus closes

Physical Findings: 1. Palpable right ventricular impulse at lower sternal border (because RV has to pump against systolic pressure)

  • 2.

    Accentuated S2 (closure of aortic valve closer to chest wall)

  • 3.

    No prominent murmurs unless there is an additional defect

Diagnostic Imaging and Testing:

  • A.

    Chest x-ray: usually normal, base of heart may be narrow

  • B.

    ECG: RVH

  • C.

    Echo: shows abnormal orientation of great vessels (definitive diagnosis)

Treatment: TGA is a medical emergency. Give prostaglandin infusion to keep ductus arteriosus open. Also, use balloon catheter to create an opening in the interatrial septum. Permanent correction occurs via “arterial-switch:” transaction of great vessels above semilunar valves and ostia of coronary arteries. Great vessels switched, and coronary arteries relocated to “new” aorta Etiology: great vessels arise from the opposite ventricle, cause is unknown but thought to be from failure of aorticopulmonary septum to spiral or from abnormal growth of subpulmonary and subaortic infundibuli

Pathology: RVH

Pathophysiology: pulmonary and systemic circulations are in parallel rather than in series, deoxygenated systemic blood passes into RA and RV and returns to circulation, oxygenated blood from lungs goes to LA and LV and returns to lungs. If no mixing of the two systems, then TGA is lethal. However, if ductus arteriosus and foramen ovale remain patent, then the two sides can communicate and deliver enough O2 to the brain and vital organs.

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