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ATRIAL SEPTAL DEFECT

Dr. SALEEM HASAN

MUKKADDAM

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Embryology

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  • Gestational Week 4 Gestational Week 4-6 •

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  • A thin, crescent shaped wedge of tissue of (septum primum) grows towards and fuses with endocardial cushions.
  • The remaining opening is called the ostuim primum. •

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  • As the septum primum is growing down, the endocardial cushions fuse and the ostium primum is eventually obliterated.

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Embryology

  • The interatrial septum forms during the first and second months of fetal development.
  • Stage I is the formation of the septum primum.
  • The septum primum walls off a crescent-shaped portion of the hole between the right and left atria.

Foramen primumramen primum (also called the ostium primum) stays open

  • The remaining part of the opening between the right and left atria is closed by the septum secundum.
  • The 2 tissue layers overlap like a flap, allowing blood flow to continue during fetal life.
  • Changes in circulation at birth, closes the flap permanently.

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Anatomy and Physiology

  • Extends from cavo-atrial junction with superior and inferior vena cavae
  • Ends near the atrio-ventricular canal near the tricuspid valve

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Ostium Secundum

  • Most common type of ASD
  • Center of the septum between the right and left atrium
  • Variant of this type of ASD is called a Patent Foramen Ovale (PFO) which is very small.

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Ostium Primum

  • Next most common type

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  • Located in the lower portion of the atrial septum.

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  • Will often have a mitral valve defect associated with it called a mitral valve cleft.

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  • A mitral valve cleft is a slit-like or elongated hole usually involves the anterior leaflet of the mitral valve.

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Sinus Venosus

  • Least common type of ASD
  • Located in the upper portion of the atrial septum.

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  • Association with an abnormal pulmonary vein connection

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  • Four pulmonary veins, two from the right lung and two from the left lung, normally return red blood to the left atrium.

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  • Usually with a sinus venosus ASD, a pulmonary vein from the right lung will be abnormally connected to the right atrium instead of the left atrium.

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  • This is called an anomalous pulmonary vein.
  • ..\asd-veno.jpg

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Foramen Ovale

  • Remnant of fetal circulation
  • Behaves like flap valve
  • Opens during increased intra-thoracic pressure

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  • Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped out to the body through the aorta.

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  • An atrial septal defect allows oxygen-rich (red) blood to pass from the left atrium, through the opening in the septum, and then mix with oxygen-poor (blue) blood in the right atrium.
  • An atrial septal defect allows oxygen-rich (red) blood to pass from the left atrium, through the opening in the septum, and then mix with oxygen-poor (blue) blood in the right atrium.

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DEFINITION

  • An atrial septal defect is an opening in the atrial septum, or dividing wall between the two upper chambers of the heart known as the right and left atria..

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GROSS SPECIMENS

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EMBRYOLOGY

  • The heart is forming during the first 8 weeks of fetal development. It begins as a hollow tube, then partitions within the tube develop that eventually become the septa (or walls) dividing the right side of the heart from the left. Atrial septal defects occur when the partitioning process does not occur completely, leaving an opening in the atrial septum.

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HEMODYNAMICS

  • RT.ATRIUM RECEIVES BLOOD FROM SUP. & INF.VENA CAVA & FROM LT. ATRIUM
  • RT.ATRIUM ENLARGES

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HEMODYNAMICS

  • LARGE VOL OF BLOOD FROM RT.ATRIUM PASSES THRU NORMAL TRICUSPID VALVE & PULMONARY VALVE

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  • DELAYED DIASTOLIC MURMUR(LOW LT STERNAL BORDER)
  • RT.VENTRICLE ENLARGES
  • PULMONARY EJECTION MURMUR

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HEMODYNAMICS

  • PULM. VALVE CLOSES LATE & P2 IS DELAYED
  • RV IS FULLY LOADED,SO FURTHER RISE IN RV VOLUME CANNOT OCCUR
  • WIDELY SPLIT S2

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  • FIXED SPLIT S2

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  • ACCENTUATED S2

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PRESENTATION

  • recurrent chest infections
  • fatigue
  • sweating
  • rapid breathing
  • shortness of breath
  • poor growth

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ON EXAMINATION

  • INSPECTION
  • PARASTRNL IMPULSE
  • PALPATION
  • SYSTOLIC THRILL AT 2ND LT SPACE

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AUSCULTATION

  • WIDE FIXED SPLIT S2
  • ACCENTUATED P2
  • ESM AT LT 2nd & 3rd INTERSPACES
  • DELAYED DIASTOLIC MURMUR AT LOW LT INTERSPACE

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CXR FINDINGS

  • MOD. CARDIOMEGALY
  • RA ENLARGEMENT
  • RV ENLARGEMENT
  • PROMINENT MAIN PULM ARTERY
  • PLETHORIC LUNG FIELDS

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ECG CHANGES

  • RT AXIS DEVIATION
  • RT VENT HYPERTROPHY
  • rsR’ PATTERN IN V1

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ECHO PICTURES

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SEVERITY ASSESMENT

  • INTENSITY OF THE TWO MURMURS
  • THE HEART SIZE

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COMPLICATION

  • PULMONARY HYPERTENSION(ABOVE 20 YEARS)
  • DISAPPEARANCE OF DIASTOLIC MURMUR
  • APPEARANCE OF PULM EJECN CLICK
  • LOUD PALPABLE P2
  • P2_STILL WIDELY SPLIT

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MANAGEMENT

  • MEDICAL
  • ANTIBIOTICS FOR CHEST INFECTIONS
  • DIGOXIN TO INCREASE WORK OF HEART
  • DIURETICS TO REDUCE PRELOAD

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SURGICAL REPAIR:DEVICES

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REPAIR