PATHOPHYSIOLOGY OF CYANOTIC CHD

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PATHOPHYSIOLOGY OFCYANOTIC CHD

• BY
• J. A. AL-ATA
• COSULTANT ASSISTANT PROFESSOR OF PEDIATRIC
  CARDIOLOGY

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CYANOSIS

• BLUISH discoloration of SKIN MM due to
  doxyhemoglobin.
• Desaturated arterial blood Central cyanosis.
• Peripheral cyanosis Normal Art. Sat.
• Detected clinically ( sat below 85 ), pulse
  oximetry, or ABG.

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CAUSES OF CYANOSIS

• Central cyanosis
• Respiratory
• CNS
• Muscular
• Cardiac
• Peripheral cyanosis
• CHF
• Shock
• Acrocyanosis
• Abnormal hemoglobin

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Types of Cyanotic CHD

• With pulmonary blood flow
• D-TGA
• Truncus arteriosus
• TAPVD
• DORV
• Single ventricle no ps.
• With pulmonary blood flow
• TOF
• Critical pulmonary stenosis
• Pulmonary Atresia

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D-TGA

• Parallel circulation not in series
• Body----RA----RV----AO----Body
• Lungs---LA----LV----PA----Lungs
• Poor mixing
• Hypoxia Acidemia
• Hyperventilation
• Increased pulmonary flow
• CHF
• Myocardial depression

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TRUNCUS ARTERIOSUS

• Complete mixing so cyanosis is minimal
• VSD always present
• Identical pressures in both ventricles
• Systemic saturation is proportional to pulmonary
  blood flow ( PBF )
• PVR PA.s caliber determine PBF
• CHF is a usual presentation
• Eisenmenger syndrome may develop
• AS AI are complicating factors

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TAPVR

• NON-Obstructed TAPVR
• Similar hemodynamics to a large ASD
• Lt to Rt shunt magnitude is determined by RV
  compliance ASD size
• Rt heart pulmonary volume overload
• Complete mixing at RA level
• Minimal cyanosis due to large PBF
• Slight PA pressure elevation

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TAPVR, CONT

• Obstructed TAPVR
• Pulmonary venous hypertension secondary PA RV
  hypertension
• Less RV PA volume overload
• Pulmonary venous oedema
• More cyanosis respiratory distress
• Complete mixing

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TRICUSPID ATRESIA

• Increased RA pressure size
• Dependant on the ASD or PFO
• Dilated LA LV
• Complete mixing in LV
• With TGA PBF SAT.
• Variable degree of cyanosis

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EBSTEIN ANOMALY

• Variable degrees of cyanosis depending on amount
  of Rt to Lt shunt across ASD or PFO
• Hugely dilated RA
• Incompetent TV
• Atrialized small poorly functional RV
• RVOTO PS can be associations
• SVT ( WPW ) can be associated

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TETRALOGY OF FALLOT

• Decreased PBF Amount of RT to LT shunt
  determine degree of cyanosis
• PBF is mainly determined by RVOTO PS
• Pink TOF mod RVOTO balanced shunting across
  the VSD
• Increased PBF can result from PDA or MAPCAS
• Equal ventricular pressures

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HYPERCYANOTIC SPELL
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PULMONARY ATRESIA

• With VSD
• An extreme form of TOF
• Early cyanosis when PDA closes
• Ductal dependant
• CHF with MAPCAS / PDA
• Balanced form

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PULMONARY ATRESIA CONT

• Without VSD
• Early marked cyanosis ( extremely decreased PBF )
• Ductal dependant
• RV sinusoids
• RV decompression by TR
• ASD or PFO mandatory

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SUMMARY

• Central cyanosis is the hallmark of cyanotic CHD
• Cyanosis is a serious symptom or sign
• Variable degrees of cyanosis occur due to
  variability in PBF, PVR, RVOTO, presence size
  of shunting site e.g. ASD and hemoglobin
  concentration
• CHF can occur in cyanotic CHD due to increased
  PBF
• Pulmonary AVMs Methemoglobinemia are
  non-cardiac causes of central cyanosis.

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Thank You