Congenital Pediatric Heart Disease

Congenital Pediatric Heart Disease – Board Review  (PDF with pictures)

Basic Pathophysiology

Fetal Circulation

  • Have shunts to bypass liquid filled lungs
  • Oxygenated blood from mom goes through placenta into baby via umbilical vein
    • Half the blood goes to liver
    • Half goes to ductus venosus to inferior vena cava where it mixes with deoxygenated blood returning from lower half of body
      • IVC and SVC (this is deoxygenated blood returning from upper half of body) meet at right atrium
        • Blood then goes to either:
          • LA via foramen ovale to LV to aorta
          • RV which then goes to pulmonary artery where most is shunted away from lungs via ductus arteriosus into aorta
          • Small amount goes to lungs to provide oxygen and nutrients for growth

 

Transitional Circulation

  • When baby is born, lungs expand and fill with air with gradual reabsorption of fetal lung fluid – this increases PaO2 of blood flowing in the lungs which in turn mediates transition from fetal to neonatal lung patterns
  • Flow through umbilical arteries stops and venous flow slows and stops eventually too
  • Pulmonary vascular resistance falls and pulmonary blood flow increases – this continues for the first 30-45 days of life
  • Ductus venosus and arteriosus close, this helps to continue decrease pulmonary vascular resistance, increases systemic resistance
  • LA pressures increase, resulting in closure of foramen ovale

Neonatal Cardiac Physiology

  • They have non-compliant ventricular walls, so they can’t increase SV, rely on increasing HR to increase CO – so sinus tachycardia is first response to stress (DO NOT EVER BLOW OFF TACHYCARDIA!!!)
    • Remember CO = SV x HR
    • Due to this, they are more susceptible to CHF as there is but so much one can increase HR before it is not effective
  • Ductus arteriosus closes within first 15 hours of life
  • Foramen ovale closes within first 3 months of age

Basics of Congenital Heart Disease

  • According to professionals like the ones at HTTPS://WWW.CAROLINACARDIOLOGYASSOCIATES.COM/, congenital heart defects can present at any age in a spectrum from cyanosis, cardiovascular collapse to CHF
  • Occur in 1 in 1000 births
  • Cyanotic vs Acyanotic
  • Cyanotic – Terrible Ts
    • Tetralogy of Fallot
    • Tricuspid anomalies – tricuspid atresia and Ebstein’s anomaly
    • Truncus arteriosus
    • Total anomalous pulmonary venous return
    • Transposition of great arteries
  • Acyanotic
    • VSD – ventricular septal defect
    • ASD – atrial septal defect
    • PDA – patent ductus arteriosus
    • Atrioventricular canal
    • Coarctation
    • Pulmonary stenosis
    • Aortic stenosis
  • Cyanosis
    • In order for cyanosis to be present, 3-5 mg/dL has to be deoxyhemoglobin – this corresponds to 70-80% O2 sat
    • Here we are referring to central cyanosis – best places to look mucous membranes in mouth, under tongue, not just lips

Tetralogy of Fallot

  • Most common cyanotic lesion – 10% of all pediatric cardiac anomalies
  • Four characteristics: large VSD, right ventricular outflow obstruction (due to pulmonic stenosis), overriding aorta, right ventricular hypertrophy
  • Intensity of cyanosis depends on the amount of obstruction of right ventricular outflow tract
    • This also determines the shunting through VSD
      • Severe pulmonic stenosis à R -> L shunt à this will lead to cyanosis
      • Mild pulmonic stenosis à L -> R shunt à these are the ones you may discover later, will have stories of TET spells and episodic cyanosis, and can be helped by flexing hips and knees to increase pre-load
    • CXR – boot shaped heart with decreased pulmonary markings

Transposition of Great Vessels

  • Most common to present in newborn period – 6-8% of all pediatric cardiac anomalies
  • Aorta arises from R ventricle and pulmonary artery arises from L ventricle
    • So you need communicating systems as this is not compatible with life – need VSD, ASD, PDA or any combination of those
  • CXR – egg on a string, narrow mediastinum, increased pulmonary markings

Total Anomalous Pulmonary Venous Return

  • 1% of all pediatric cardiac anomalies
  • Pulmonary veins empty into R ventricle after returning from lungs instead of emptying into L ventricle
  • Four types: depending on where the veins are emptying
    • Supracardiac (empty into SVC) – 50%
    • Cardiac (empty into coronary sinus) – 20%
    • Infracardiac (empty into portal vein, hepatic artery, IVC, ductus venosus) – 20%
    • Mixed lesions – 10%
  • Again, not compatible with life without communications – need VSD or PDA or both
  • CXR – Snowman sign, cardiomegaly, increased pulmonary markings

 

 

Tricuspid Atresia

  • 1-2% of all pediatric cardiac anomalies
  • Absence of tricuspid valve resulting in underdeveloped RA, RV and decreased flow to pulmonary vasculature
  • Again, not compatible with life without communications – need VSD or PDA or both
  • CXR – Normal heart with decreased pulmonary markings

 

 

Truncus Arteriosus

  • <1% of all pediatric cardiac anomalies
  • All pulmonary, systemic and coronary circulations arrive from one arterial trunk
  • Have to have various other abnormalities to be compatible with life such as VSD, ASD, PDA, coronary artery irregularities
  • CXR – Cardiomegaly with increased pulmonary markings

Written by Hima Kumar MD PGY-4