My Clinical Notes

• Cardiac or great vessel abnormalities present at birth
• Mostly due to faulty embryogenesis between weeks 3 to 8
• Have an incidence of 1% of live births

 

Aetiology

• Genetic factors identifiable in 10% of cases e,g, Downs syndrome ASD
• Environmental factors are congenital rubella infection and teratogens

 

Clinical features

• May be cyanotic
• Failure to thrive
• Retarded development
• Increased risk of chronic or recurrent illness and endocarditis

 

• Two types of abnormality – shunts and obstructions

 

Shunts

• Abnormal communication between heart chambers or between vessels or between chambers and vessels

 

Left to right shunts

 

• Induce chronic right sided volume overload and pulmonary hypertension
• Cyanosis occurs late when the pressure within the right side exceeds left sided pressure to reverse the shunt from right to left
• The major left to right shunts are;
  • Atrial septal defect (ASD)
  • Ventricular septal defect (VSD)
  • Patent ductus arteriosis (PDA)

ASD

• Most common congenital anomaly seen in adults
• Primum type – 5%. Common in Downs syndrome. Occurs low in the atrial  septum and can be associated with mitral valve defects
• Secundum type – 90% , occurs at the foramen ovale and is generally not associated with any other anomalies
• Sinus venosum type – 5%. Occurs high in the septum near to the SVC entry
• May be asymptomatic until adulthood

VSD

• Most common congenital cardiac abnormality
• Commonly associated with other anomalies in particular, Tetralogy of Fallot
• 90% involve the membranous septum and the rest are muscular of origin
• May spontaneously close

PDA

• In the fetus the ductus arteriosus permits blood flow from the aorta to the pulmonary artery
• Closes within a couple of days of birth due to increased oxygen tension and decreased PGE
• Can be closed early with indomethacin

 

Right to left shunts

 

• Cause cyanosis from the outset
• Secondary findings are;
  • Clubbing
  • Hypertrophic osteoarthropathy
  • Polycythaemia
• The major right to left shunts are;
  • Tetralogy of Fallot
  • Transposition of the great arteries
  • Tuncus arteriosus

Tetralogy of Fallot

• Cardinal findings are;
  • VSD
  • Right ventricular hypertrophy
  • Pulmonary artery stenosis
  • Aorta overriding the ventricular septum
• With complete pulmonary obstruction, survival is through the patent PDA
• Pulmonary stenosis protects the lungs from pressure overload
• Right ventricular failure is rare because it can pump excess volume into the left ventricle and aorta

Transposition of the Great arteries

• Aorta arises from the right ventricle and the pulmonary artery from the left ventricle
• Pulmonary and systemic circulations are therefore separate
• Particularly common in children of diabetic mothers
• Postnatal life depends on there being some mechanism of blood mixing, PDA, VSD, ASD

Truncus arteriosus

• Failure of the aortic and pulmonary artery to separate
• Results in a single vessel receiving blood from both left and right ventricle
• Right to left shunting causes early cyanosis
• Later the flow reverses resulting in right ventricular hypertrophy and pulmonary hypertension

 

Obstructive congenital anomalies

 

• Do not cause cyanosis

 

Aortic coarctation

• Constriction of the aorta
• Cardiac hypertrophy can occur due to pressure overload
• Clinical manifestations depend on location and severity of the constriction
• Preductal – before the ductus arteriosus. Often rapidly fatal
• Postductal – occurs distal to the ductus arteriosus. Generally asymptomatic, leads to upper extremity hypertension with lower body hypotension with arterial insufficiency (claudication, cold sensitivity). Collateral flow develops around the coarctation via internal mammary and axillary artery dilation, resulting in intercostals rib notching on CXR

Pulmonary stenosis or atresia

• In complete pulmonary atresia the right ventricle is hypoplastic and there is an ASD with blood entering the lungs via the PDA

 

Aortic stenosis or atresia

• Complete aortic atresia is rare and generally is incompatible with neonatal survival. The can only surve is a patent PDA allows blood flow to the aorta and coronary vessels
• Resulting underdevelopment of the left ventricle is called hypoplastic left heart syndrome
• Consequences of aortic stenosis are;
  • Infective endocarditis
  • Left ventricular hypertrophy
  • Post-stenotic dilation of the aortic root
  • Sudden death

 

This entry was posted on Wednesday, February 13th, 2008 at 5:29 pm and is filed under Cardiovascular. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.