Talk about development of the fetal heart p1
The fetal heart begins to develop around 3 weeks gestation and it beats by the 4th week.
The heart develops from the mesoderm near the head AKA cardiogenic area
The cardiogenic area then forms two strands known as cardiogenic cords which develops lumens becoming endocardial tubes.
Communications form between the endocardial tubes which fuse to form the primitive heart tube
P2 of development of the fetal heart
The caudal aspects of the heart tube dilates to form early atria .
The bulbus cord is gives rise to the right ventricle
The truncus arteriosus also rises from the bulbus cordis and becomes the aortic root and parts of the ascending aorta.
The truncus arteriosus also develops into the posterior portion of the right atrium the SA nose and th coronary sinus
The cranial aspects dilates to form the aortic sack which gives rise to the aortic arches
P1 of fetal circulation
Oxygenated rich blood from the placenta flows to the fetus through the umblical vein.
Which bypasses the liver by the ductus venosus and enters RA via the inferior vena cava .thr oval foramen then shuts the blood from the ra into the la . The blood then passes into the lv and out through the aorta to the fetal systemic circulation
P2 of fetal circulation
Deoxygenated blood returning from the head and neck flows through the superior vena cava and combined with some of the remaining oxygenated blood in the ra.
Thus passes into the right ventricle into the pulmonary arteries.
As there is a high pulomonary vascular resistance blood bypasses and is shunted through the ductus arteriosus from the PA to the aorta . Mixed oxygenated and deoxygenated blood sufficient oxygen level for needs of fetus
Deoxygenated blood is recycled back to the placenta through the descending aorta and umbilical arteries
Neonatal circulation ?
Once the baby is delivered and respiration begins the pulmonary resistance decreases causing blood from the pulmonary artery trunk to enter the right and left pulmonary arteries
This blood then becomes oxygenated at the lungs retuning the left atrium via pulmonary vein.the oval foramen ductus arteriosus and venosus close. The umbilical vein and arteries now occlude.
What is congenital heart disease (CHD)
Is a heart condition or defect that develops in the womb before a baby is born.
Heart defects are the most common congenital anomaly in babies born in the UK
Heart disease is the biggest cause of perinatal and infant mortality from congenital anomalies
What is ventricular septal defect ? VSD
Most common type of heart defect.
Increases blood flow from the left side to the right side of the heart, increasing pressure of blood into the lungs and making the heart work harder.
Small VSDs are often asymptomatic and infants can have a normal life.large VSDs can cause cardiac failure at birth.
If there are no symptoms in infancy then they don’t chase problems until adolescence or adult hood when fatigue, breathlessness, cyanosis or high pulmonary vascular resistance.
Can lead to pulmonary hypertension and arrthymias.
Large VsDs needs to be closed surgically
What is coarctation of the aorta
Narrowing of the aortic lumen.
Usually appears in adults with hypertension
Surgical repair like balloon angioplasty
Hypertension must also be treated
What is Atrial septal defect (ASD)
Blood is shunted from the left atrium to the right atrium which increases volume load and dilation of the right atrium and ventricle. Imcrease pulmonary blood flow and enlargement of the pulmonary vessels and reduces the filing of the left ventricle and aorta.
Secundum- occurs in the middle of the atrial septum most common and can close naturally or using device.
Sinus venosus - occurs in the upper part of the septum, rare and can’t close naturally.
Primum- occurs in the lower part of the septim and involved a compete or partial atrioventricular septal defect , needs surgical closure
Overall thus defect can lead to pulmonary hypertension , arrthmyias asn enlargement of the right atria and ventricles
What is valve stenosis ?
Can occurs in the valves like the aortic and pulmonary valve which are narrowed causing them to reduce or prevent blood flow.for e.g a valve that has leaflets that are partially fused together or a valve that has thick leaflets that don’t open all the way
What are the causes of congenital heart disease
Remains unknown but include
Infections (flu, rubella )
Smoking
Alcohol
Maternal diabetes
Certain medications
Genetic changes
A pregnant person will be sent for a fetal echocardiogram if a routine 20. Week scan suggests a heart abnormality , family history of this disease , maternal diabetes or mother is taking certain medications
How are congenital heart diseases detected ?
Missed cases - need high quality images and skills knowledge to diagnose CHD, if it is missed this increases infant morbidity and mortality as they often need very specialised care shortly after birth
Diagnosis after birth - physical examinations of the baby after birth ( listening to the heart , feeling pulse ) , characteristic signs after birth include blue colouring of the skin and lips (cynosis)
How to prevent CHD- vaccinations against rubella and flu, avoid alcohol , smoking ,folic acid supplement in the first trimester
What is transposition of the great arteries (TGA)
Where the aorta connects to the right ventricle and the pulmonary artery connects to the left ventricle .
This physiology is therefore not compatible with life and the neonate would die instantly if not for the presence of the open oval foramen ir ASD , VSD.
Treatment involves an arterial switch procedure to switch the arteries back to their appropriate ventricles.
What is patent ductus arteriosus (PDA)
The ductus arteriosus remains open.
It causes the flow of blood from the aorta to the pulmonary circulation which causes a murmur
>50 % of cases is asymptomatic
If there is a bigger shunt it can lead to heart failure.
Treatment is surgical closure of the duct
Fallot tetralogy
Is an abnormally positioned aorta that overrides the interventricular septum thus causes systemic circulation to receive too much oxygen poor blood which causes VSD, pulmonary stenosis.
Babies who are not strong enough for a full repair surgery or have other health problems may have a shunt operation .shunt = a tube that is sewn into place between the aorta and the pulmonary artery , helps blood flow to the lungs
A full tetralogy of fallot repair surgery involves placing a patch over the ventricular septal defect removing thickened tissue from the rv widening the pulmonary valve
What is hypoplastic left heart
Left side of the heart is under developed
The mitral valve or the aortic valve are either very narrow or blocked.
Aorta is small n under developed
ASD
Once the ductus arteriosus close after birth the in hypoplastic left heart syndrome the only way the blood can get to the aorta is through the ductus arteriosus
Prostaglandin can be given to keep the duct open
Norwood procedure - gets the rv to pump blood into the aorta by separating the main pulmonary artery from the right and left branches and join it to the upper part of the aorta .
The right and left pulmonary artery blood supply is then provided by a shunt placed between the aorta and the pulmonary artery or the rv and pa
. Heart transplant
