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Cardiovascular Pathology

Congenital Heart Diseases

Definitions
  • Atresia: complete obstruction
  • Atrophy: decrease in the volume & muscle mass of a cardiac chamber that occurs after birth
  • Hypoplasia: decreases in the volume & muscle mass of a cardiac chamber that occurs before birth
  • Shunt: abnormal communication between chambers or vessels.
  • Eisenmenger Syndrome: when left to right shunting of blood leads to pulmonary vascular hypertension that is close to systemic pressure and the shunt reverses to become a right to left shunt
  • Cyanosis: blueish color seen in skin and mucus membranes that is due to deoxygenated venous blood being shunted into the systemic arterial system
  • Clubbing aka hypertrophic osteoarthropathy: distal blunting and enlargement of fingers and toes due to prolonged and severe cyanosis. (1)(2)
Classification of Congenital Heart Diseases (CHDs)
A. Left to Right Shunts: ASD, VSD, PDA

B. Right to Left Shunts: PTA, TGA, TA, TOF, TAPVR
  • Paradoxical emboli: emboli from peripheral veins bypass pulmonary circulation and enter the systemic circulation via the right to left shunt
  • Polycythemia
  • Hypertrophic osteoarthropathy "clubbubg"
  • Cyanosis  
C. Others: Coarctation of the Aorta, Pulmonary Atresia, Aortic Atresia 
  1. Atrial Septal Defect (ASD)
    • ASDs are fixed openings in the atrial septum between the left atrium and the right atrium. They are classified by their location:(1)(2)
      • Secundum (90%) - failure of septum secundum causing a more central opening in the atrial septum
      • Primum (5%) - failure of endocardial cushion development causing a more inferior opening in the atrial septum near the AV valves
      • Sinus Venosus (5%) - opening is near the superior vena cava or inferior vena canva (*)
    • Review of embryology of septal formation (1)(2)(3)
    • Presentation
      • LA -> RA blood flow causing pulmonary blood flow to increases substantially
        • more blood passing through the tricuspid valve causes a diastolic rumble and a loud S1
        • more blood passing through the pulmonary valve causes a pulmonary flow murmur and a wide fixed split of S2 heart sound (delayed pulmonary valve closure)

      • Patients may be asymptomatic (no cyanosis) until age 30, but the shunt can reverse (Eisenmenger syndrome) leading to cyanosis. May progress to heart failure
      • Associated with Down's syndrome - most commonly ostium primum type
  2. Ventricular Septal Defect (VSD)
  3. Patent Ductus Arteriosus (PDA)
  4. Persistent Truncus Arteriosus (PTA)
  5. Transposition of the Great Arteries (TGA)
  6. Tricuspid Atresia
  7. Tetralogy of Fallot
  8. Total Anomalous Pulmonary Venous Return (TAPVR)
  9. Coarctation of the Aorta
    • Coarctation of the aorta = congenital narrowing of the descending aorta, usually near the ligamentosum arteriosum (remnant of fetal "ductus" arteriosus). The narrowing can be before the ductus (preductal), at the ductus (juxtaductal), or after the ductus (postductal). Accounts for approx. 8% of all congenital heart diseases
    • Infantile type (usually preductal)
      • usually just proximal to the left subclavian artery.
      • occurs in 10% of patients with Turner Syndrome
      • Before ductus arteriosus closes/ or with a PDA:
      • After ductus arteriosus closes (after first few days of life): The left ventricular has to pump against the increased pressure and this can lead to heart failure, also lack of blood supply to the body can lead to shock.
      • Maintain a PDA with PGE1
      • Links: (1)
    • Adult type (usually postductal) - "adult" because it's less severe and doesn't present in neonates, can take years before noticed
      • usually just distal to the left subclavian artery.
      • most commonly seen in children
      • collateral circulation to bypass narrowing:
        • Intercostal arteries: rib notching (1,2,3), pulsation, 
      • Claudication in lower extremities: leg pain & cramping during exercise
      • Radio-femoral delay (weak, delayed femoral pulse compared to radial pulse), due to the decreased blood supply reaching the lower extremities
      • Hypertension in upper body
      • Left ventricular pressure increases as it tries to pump against the narrowed aorta --> systolic ejection murmur heard in the back (usually over scapula, may have scapular bruit)
      • 50% also have a Bicuspid Aortic Valve which can also produce a murmur
      • increased risk of intracerebral hermorrahge due to development of berry aneurysms from the increased cerebral blood flow via the left common carotid
    • Diagnosis
      • CXR shows rib notching, figure 3 sign (1)
      • Echocardiography to confirm presence of coarctation
      • Aortogram (CT/MRI)
    • Treatment
      • Balloon dilatation, stenting
      • surgery
      • AHA/ACA 2008 guidelines here
        •  
         
Congenital Heart Disease Associations
    • Down Syndrome: Endocardial Cushion defect (ostium primum ASD, regurgitant atrioventricular (AV)), VSD
    • Turner Syndrome: Coarcatation of Aorta, Bicuspid aortic valve
    • Marfan Syndrome: Cystic medial necrosis --> aortic aneurysm & dissection, Mitral Valve prolapse
    • DiGeorge Syndrome (22q11 syndrome): TOF, interrupted aortic arch, truncus arteriosus
    • Kartagener Syndrome: Situs inversus
    • Tuberous Sclerosis: cardiac rhabdomyomas -> valvular obstruction
    • Friedreich Ataxia: Hypertrophic cardiomyopathy
    • Infant of Diabetic Mother: transposition of great arteries
    • Congenital Rubella: Septal defects, PDA, pulmonary artery stenosis

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