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Cardiovascular Embryology and Congenital abnormalities
- 1. Embryology of the Heart
- 2. Why bother? • Genetic Evolution • Insight into post-natal anatomy • Understand congenital disease • Treating adult diseases with embryonic processes
- 4. To this
- 5. Gastrulation • Mass Movement and invagination of the blastula (ball of cells) to form three layers – Ectoderm – Mesoderm – Endoderm
- 6. Each layer forms: • Ectoderm – Skin, nervous system, neural crest (coronary arteries and cardiac outflow) • Mesoderm – All muscle types, most systems (including CV), blood and kidneys • Endoderm – GI Tract (liver and pancreas) endocrine organs
- 7. Cardiovascular Embryology • Mesoderm – Smooth muscle, blood, heart, endothelium • Ectoderm – Neural crest cells • Question: When does it start?
- 8. Day 15 • First heart field is RED • The Second heart field is YELLOW • The first HF will become the left ventricle • The second will become the outflow tract, future right ventricle and atria
- 9. Over time… • Day 21 – Tube • Day 28 – 4 Chambers • Day 50 – Fully functioning
- 11. Examples: • NK x 2.5 (all heart) • GATA (Right Ventricle) • Hand (Ventricles) • Tbx (all heart) • MEF2 (Right Ventricle) • Pitx2 (vena cava) • Fog-1
- 12. 3 stages of cardiac formation 1. Formation of the primitive heart tube 2. Cardiac looping 3. Cardiac Septation
- 13. Forming the heart tube • 3rd week of development the heart is formed from the cardiogenic region (look like a horse shoe)
- 14. Day 19 • 2 endocardial tubes form • They then fuse to form a single primitive heart tube (GATA)
- 15. Endocardial tube • Becomes surrounded by myocardium and the visceral layer of the serious pericardium • Cephalic end = Arterial end • Causal end = Venous end • Arterial end is beyond the pericardium with a large vessel – Aortic sac • Heart beats at day 22 • Nkx2.5 increases heart size
- 17. Cardiac Looping – Day 23 • Bulbis Cordis moves inferiorly, anteriorly and to the embryos right • (like down, in front and right) • ORANGE Cha Cha slide
- 18. Continued • The primitive ventricle moves to the embryos left side • (RED Box to the left)
- 19. Continued • Primitive atrium and sinus venousus move superiorly and posterior • (Green and blue Love lifts us up where we belong) • The sinus venousus is posterior to the primative atrium
- 20. So far • Cha Cha slide • Box to the left • Love lifts us up
- 21. Atrioventricular canal • There is only one common atrium and one ventricle at the moment • Connected by atrioventricular canal
- 22. Endocardial cushions! • There are two, the superior (on top) and the inferior (bottom) • They grow together whilst the canal is repositioning itself to the right side of the heart • They fuse to form two separate openings, left and right canals.
- 23. Side view
- 24. Cardiac Septation • Week 4 (this is going on at the same time as the growth etc) • Septum primum (crescent-shaped tissue) grows towards the endocardial tissues • The opening between the septum primum and the endocardial cushion is called the foramen primum. Shunting
- 25. • Just before the septum primum closes it forms another hole (foramen secundum) to allow shunting.
- 26. • The second bit of tissue grows towards the endocardial cushions = Septum secundum • Thick muscular compared to thin first one
- 27. End of week 6 • Septum secundum finishes growing • Permanent opening on posterior-inferior surface • Foramen Ovale
- 28. • The septum primum gradually degenerates • The lower part remains as the valve of the foramen ovale • It closes when baby is born • Fossa ovalis
- 30. Formation of blood islands “aggregations of mesenchymal cells in the angioblast of the early embryo, developing into vascular endothelium and blood cells.”
- 31. Vascularisation • Day 17-21 • Vascularisation of yolk sac, chorionic villus (absorbs oxygen) and stalk • Angioblasts from mesoderm join together to form angioblastic cords through the embryonic disc
- 32. Vasculogenesis/Angiogenesis • Day 18 onwards • Driven by growth factors • Proliferation and sprouting • Mesodermal cells are recruited
- 33. Growth factors • Make things grow • Angiogenic growth factors – vascular endothelial growth factor, – angiopoietin 1 & 2 • Repulsive signals – Plexin / semaphorin signalling, – ephrin / Eph interactions
- 34. Aortic arches: 1st and 2nd Become minor head vessels 1st – small part of maxillary 2nd - artery to stapedius
- 35. 3rd Aortic arch • Become common carotid arteries, and proximal internal carotid arteries • Distal internal carotids come from extension of dorsal aortae
- 36. Right dorsal Aortae and Right 4th • R dorsal aorta looses connections with midline aorta and 6th arch, remaining connected to R 4th arch • Acquires branch 7th cervical intersegmental artery, which grows into R upper limb • Right subclavian artery is derived from right 4th arch, right dorsal aorta, and right 7th intersegmental artery
- 37. Left dorsal Aortae and left 4th • Left dorsal aorta continues into trunk • Left 7th cervical intersegmental artery, which grows into left subclavian artery • Right subclavian artery is derived from right 4th arch, right dorsal aorta, and right 7th intersegmental artery
- 38. 5th arches There are none. HA
- 39. 6th arches • Right arch may form part of pulmonary trunk • Left arch forms ductus arteriosus – communication between pulmonary artery and aorta
- 40. This is what it looks like:
- 42. Odd one out?
- 43. Ventricular Septal Defect • Abnormal connection between the two ventricles • 20% of all heart defects • Many close on their own in childhood
- 44. VSD • High pressure in the left ventricle • Low pressure in the right ventricle • Blood flows from high to low • Some oxygenated blood gets into RV • Increased blood flow to the lungs
- 45. VSD- Size of holes • Large • High pulmonary flow in infancy • Breathlessness • Poor feeding • Need it fixed (PA band/ repair) • Eisenmenger’s Syndrome • Small • Small increase in pulmonary flow • Risk of endocarditis • No intervention needed
- 46. Clinical signs • Large • Small skinny breathless • Increased resp. rate • Tachycardia • Big heart • Murmur varies • Small • Loud systolic murmur • Thrill (buzzing) • Well grown • Normal heart rate and size
- 47. Eisenmenger's syndrome • High pressure pulmonary blood flow • Damage to pulmonary vasculature • Resistance in lungs increase • Right ventricle pressure increases • Blood flow reverses • Shunt • BLUE
- 48. Atrial Septal Defects • Abnormal connection between two atria • Septum primum/secundum or sinus venousus • Common • Present in adulthood mostly • Slightly higher pressure in the left atrium than the right atrium • Left to right shunt • NOT BLUE
- 49. ASD- Size of holes • Large • Increased flow to the right heart and lungs • Right heart dilation • Increased chest infections • SOBOE • Should be closed if its stretching the heart • Small • Small increase in flow • No right heart dilation • No symptoms • Leave it alone!
- 50. Clinical signs of ASD’s • Pulmonary flow murmur • Fixed split second heart sound (delayed closure of pulmonary valve) • BIG pulmonary arties on X ray • BIG heart • Close: – Surgical – Percutaneous (umbrella)
- 51. Atrioventricular Septal Defects • 2 in 10000 live births (common in downs) • Hole at very centre of heart • Involves Atrial septum, ventricular septum, mitral and tricuspid valves • Complete or partial • Just one massive malformed valve • Leaky
- 52. AVSD
- 53. AVSD Types • Complete • Breathless as a neonate • Poor weight gain • Poor feeding • Torrential pulmonary blood flow • Repair/PA band in infancy • Surgically challenging • Partial • Present in late childhood • Presents as a small ASD/VSD • Leave it alone if not right heart dilation
- 54. Patent Ductus Arteriosus • Aortic arch joined to the pulmonary artery
- 55. PDA- Size of holes • Large • Torrential flow from aorta to pulmonary artery • Breathlessness • Poor feeding • Common in premature babies • Surgically close • Small • Little flow from aorta to pulmonary artery • Murmur • Risk of endocarditis
- 56. Clinical Signs and Treatment • Signs • Continuous machinery murmur • Big heart and breathless • Eisenmenger’s syndrome • Blue • Clubbing • Treatments • Surgical or Percutaneous • Local anaesthetics • Venous approach (AV loop) • Low risk operation
- 57. Coarctation of the Aorta • Narrowing of the aorta at the side of insertion of the Ductus Arteriosus
- 58. Type of CA • Severe • Obstruction to aortic flow • Collapse • Heart failure • Needs urgent repair • Mild • Presents with hypertension • Incidental murmur • Repair to prevent long term problems
- 59. Clinical Signs and Long Term Problems • Signs • Right arm hypertension • Bruits (buzzes) over the scapulae and back from collateral vessels • Murmurs • Problems • Hypertension (stroke, CAD, sub arachnoid haemorrhage) • Recoarctation • Aneurysm at site of repair
- 60. Coarctation repair • Surgical vs Percutaneous • Subclavian flap • End to end repair • Coarctation angioplasty
- 61. Bicuspid Atrioventricular Valves • Normally they have 3 • This time there’s only 2 • Severely stenotic • Degenerate quicker • Regurgitate earlier • Association with coarctation and dilation of ascending aorta
- 62. Tetralogy of Fallot 1. Ventricular Septal Defect 2. Pulmonary Stenosis 3. Hypertrophy of Right Ventricle 4. Overriding Aorta • Shunt from RV to LV • Blue Cause 10% of all heart defects
- 63. Clinical Signs and Repair • Signs • Cyanosed • Clubbed • Harsh Systolic murmur from the right ventricle outflow tract obstruction (RVOT) • Repair • By the age of 2 • Close the VSD • Resect the RVOT obstruction • They may get pulmonary valve obstruction in adult life
- 64. Pulmonary Stenosis • Narrowing of the right ventricle outflow • Can be valvar, sub valvar, supra valvar, branch • 8-12% of all defects
- 65. Type of PS • Severe • Right ventricle collapse as a neonate • Poor pulmonary blood flow • Right ventricular hypertrophy • Tricuspid regurgitation • Moderate/mild • Well tolerated • Right ventricular hypertrophy
- 66. Treatment • Balloon valvuloplasty • Open valvostomy • Open trans-annular patch • Shunt to bypass the blockage
- 67. Thanks for staying with me!