Congenital Heart Disease Flashcards
Aetiology of congenital heart disease
Genetic – Down
Normal physiology
In the Right atrium - de-oxygenated blood, with oxygen saturation being 65%
Blood then goes to right ventricle with oxygen saturation being 65%
From here goes to the pulmonary artery with oxygen saturation being 65%
From lungs comes back through pulmonary veins entering LA, with oxygen saturation being 99-100%
From here goes to LV, with oxygen saturation being 99% (same with aorta)
Pressure comes into RA at pressure of 4mmHg
Pressure in the RV varies - with diastole (relaxation) it’s 3mmHg with systole (tensing) its 25mmHg
In the pulmonary artery when valve opens pressure is 25mmHg, when the valve shuts the pressure goes back down to 10mmHg
In the LA the blood enters under the pressure of 5mmHg
In the LV the blood pressure varies - under diastole the pressure is 4, under systole the pressure in th heart is 80mmHg
In the aorta the pressure when valve opens is 80mmHg, when the valve closes the pressure is 40mmHg
Classification of congenital heart disease
Acyanotic
Left to right shunts: ASD,VSD,PDA (patent ductus arteriosus)
Obstructive lesions: Aortic stenosis (Hypoplasia) Pulmonary stenosis (Valve, outflow, branch) Coarctation of the Aorta, Mitral stenosis
Cyanotic (Complex, Right to Left shunts)
– Tetralogy of Fallot (VSD/Pulm stenosis …)
– Transposition of the Great Arteries
– Total Anomalous Pulmonary Venous Drainage
– Univentricular Heart
Haemodynamic effects or left to right (acyanotic) shunts and right to left shunts (cyanosis)
Left to right shunt -
Requires a hole !
Blood from the left heart is returned to the lungs (as it goes to the right side of the heart) instead of going to the body – Increased lung blood flow by itself is not damaging, But due to this increased volume of blood it leads to increased pulmonary artery or pulmonary venous pressure which is damaging.
Right to left shunt -
Requires a hole and distal obstruction!
De-oxgenated blood bypasses the lungs and stays in single system with the body, very oxygenated blood stays with the lungs and very little of it reaches the body
Atrial and ventricular septal defects
Atrial septal defects Haemodynamic effects 1. Increased pulmonary blood flow 2. RV Volume overload 3. Pulmonary hypertension is rare 4. Eventual Right Heart Failure
Ventricular Septal Defects
Illustrating the different locations of VSD
Tetralogy of fallout
Occurs due to a variety of problems
1st problem occurs during embryology - when heart is growing, embry will experience narrowing of pulmonary valve -which can come with an overriding aorta which sits below the pulmonary valve - this then means the heart grows slightly to the left - so aorta is sitting where the heart wants to create its septum so it cant so a gap appears (problem 1 - overriding aorta)
2nd issue is due to the narrowing of the pulmonary valve the pulmonary artery will experience stenosis(the valve cant open 100%), this creates a pressure increase in the right ventricle (2nd problem pulmonary valve stenosis)
Following this the 3rd issue is, due to the increased pressure in the RV, it begins to hypertrophy - increasing the size of the right side of the heart
Problem 4 - due to the hypertrophy, the small septal defect at birth is now worsened as the heart size increases - but since the pressure in the right side of the heart is greater than the left side (due to the stenosis) the blood flows from right to left making it a cyanotic shunt
Tricuspid Atresia
Congenital heart defect where the tricuspid valve tissue hasn’t formed - instead there is just solid tissue between the 2 chambers (RV is seriously underdeveloped) - usually occurs with atrial septal defect - so de ox blood mixes with oxygenated blood and a mixture of the 2 bloods are sent to the body and lungs
A baby, child or adult with tricuspid atresia can’t get enough oxygen through its body. People with this condition tire easily, are often short of breath and have blue-tinged skin.
Tricuspid atresia is treated with multiple surgeries. Most babies with tricuspid atresia who have surgery live well into adulthood, though follow-up surgeries are often needed.
Transposition of the great arteries
Life threatening in the transition phase from going from in utero to trying to survive in world as in utero heart is a single channel, whereas when all the shunts close during first breath,with this disease, 2 separate routes develop for blood - oxygenated blood stays with lungs and deoxygenated blood stays with the body
It occurs due to
1) RV connected to Aorta
2) LV connected to Pulmonary Art
3) Not viable for life unless the two circuits communicate connect via atrial, ventricular or ductal shunts
4) Example of bi-directional shunting
Hypoplastic left heart
Congenital birth defect - incompatible with life outside womb - left side of the heart is underdeveloped (not formed properly)
As a conscequence the aorta is very small and the right side of the heart supports systemic circulation in utero - due to the presence of the foramen ovale
For even short term survival there must be an atrial septal defect and a patent ductus Arteriosus (therefore connecting the pulmonary artery and the aorta), to allow some oxygenated blood to reach systemic body
Natural history and clinical relevance of common congenital heart diseases
ASD: Usually asymptomatic late into adulthood. Late onset arrythmia and Right Heart Failure
VSD: Unless very small, present in infancy with Left Heart Failure. Untreated, can lead to in-operable pulmonary hypertension
Coarctation – Neonatal variety: associated with PDA, R to L shunt
– Adult variety: complicated by Renal Hypertension, Left Vent Hypertrophy, often associated Aortic Valve Stenosis
Tetralogy of Fallot: Present in infancy or early childhood with
Cyanotic spells. Mild cases compatible with adulthood
Transposition/ hypoplastic left heart/Pre-ductal Coarctation/Pulmonary atresia: Presenting as Neonatal emergencies, often due to reduced pulmonary blood flow
