Congenital Heart Disease Flashcards
Describe the frequency and types of congenital malformations of the heart and great vessels
Very common, 6-8 per 1000 births
Ventricular Septal Defects are more common than Atrial Septal Defects
What is transposition of the great vessels?
Transposition of the great vessels (TGV) is a group of congenital heart defects involving an abnormal spatial arrangement of any of the great vessels: superior and/or inferior venae cavae, pulmonary artery, pulmonary veins, and aorta.
Congenital heart diseases involving only the primary arteries (pulmonary artery and aorta) belong to a sub-group called transposition of the great arteries
What is Tetralogy of Fallot?
Cyanotic heart defect characterised by:
- Pulmonary stenosis
- Ventricular Septal Defect
- Right Ventricular Hypertrophy
- Over-riding aorta
What are the acyanotic heart defects?
Left to right shunts
- Atrial Septal Defect
- Ventricular Septal Defect
- Patent Ductus Arteriousus
Obstructive lesions
* Aortic, Mitral and Pulmonary stenosis
Coarctation of the Aorta
What are the cyanotic heart defects?
To be cyanotic, right pressure must be higher than left
- Tetralogy of Fallot
- Transposition of the great arteries
- Total Anomalous Pulmonary Venous Drainage
- Univentricular heart
Briefly explain Atrial Septal Defect
Transposition of the great vessels (TGV) is a group of congenital heart defects involving an abnormal spatial arrangement of any of the great vessels: superior and/or inferior venae cavae, pulmonary artery, pulmonary veins, and aorta. Congenital heart diseases involving only the primary arteries (pulmonary artery and aorta) belong to a sub-group called transposition of the great arteries
What is the foramen ovale?
In the fetal heart, the foramen ovale allows blood to enter the left atrium from the right atrium. It is one of two fetal cardiac shunts, the other being the ductus arteriosus (which allows blood that still escapes to the right ventricle to bypass the pulmonary circulation). In most individuals, the foramen ovale closes at birth. It later forms the fossa ovalis.
Briefly explain a patent foramen ovale (PFO)
PFOs are not a true ASD. PFOs may be present in ~20% of the population and are generally clinically silent, since the higher left atrial pressure causes functional closure of the flap valve.
A PFO may however be the route by which a venous embolism reaches the systemic circulation if pressure on the right side of the heart increases even transiently. This is called a paradoxical embolism.
Briefly explain ventricular septal defects (VSD)
VSDs are an opening in the Interventricular Septum. This most commonly occurs in the membranous portion (upper part) of the septum, but can occur at any point. Since left ventricular pressure is much > than right, blood will flow left to right.
Briefly explain patent ductus arteriosus (PDA)
The ductus arteriosum diverts foetal blood from the right heart to the aorta, diverting it away from the lungs.
When the lungs are perfused, their pressure drops and the ductus arteriosum should close.
If it does not close, this is a PDA
Blood will thus flow from the aorta to the pulmonary arteries, thus is an acyanotic defect.
Chronic left to right shunting can lead to pulmonary remodelling.
If R pressure exceeds L, then the shunt reverses. This is called Eisenmenger syndrome.
What is coarctation of the aorta?
Coarctation of the Aorta is a narrowing of the aortic lumen in the region of the ligamemtum arteriosum (former ductus arteriosus). The narrowing of the aorta increases the afterload on the left ventricle and can lead to left ventricular hypertrophy. Because the vessels to the head and upper limbs usually emerge proximal to the Coarctation, the blood supply to these regions is not compromised. However blood flow to the rest of the body is reduced. The extent of the symptoms depends on the severity of the Coarctation.
Explain Tricuspid atresia
Tricuspid Atresia is the lack of development of the tricuspid valve. This leaves no inlet to the right ventricle. There must be a complete Right to Left shunt of all blood returning to the right atrium (ASD or PFO) and a VSD or PDA to allow blood to flow to the lungs.
Briefly explain transposition of the great arteries
Results in two unconnected parallel circulations instead of two in series. In this defect, the right ventricle is connected to the aorta and the left ventricle to the pulmonary trunk. This condition is not compatible with life after birth, unless a shunt exists to allow the two circulations to communicate. A shunt must be maintained or created immediately following birth to sustain life until surgical correction can be made. The ductus arteriosus can be maintained patent and/or an atrial septal defect formed.
What is hypoplastic left heart?
In some cases the left ventricle and ascending aorta fail to develop properly resulting in a condition called Hypoplastic left heart. A PFO or ASD are also present and blood supply to the systemic circulation is via a PDA. Without surgical correction this is not compatible with life.
Outline the pressures and SpO2% levels of different areas of the heart and vessels
RA: 4mmHg, 60-70%
RV: 25/3 mmHg, 60/70%
PA: 25/10 mmHg, 60/70%
LA: 5mmHg, 100%
LV: 120/4 mmHg, 100%
AA: 120/80 mmHg, 99-100%
