Session 3 Flashcards
How common are congenital heart defects?
6 to 8 per 1000 births. VSD most common, followed by ASD.
Where are the most common locations of an atrial septal defect?
Foramen ovale (most common) or ostium primum . No mixing of deoxygenated blood with oxygenated blood because left atrial pressure > right atrial pressure. It is an acyanotic lesion.
What is a paradoxical embolism?
When a venous embolism passes through a patent foramen ovale it can reach the systemic circulation if pressure in the RA increases even transiently.
Where do ventricular septal defects most commonly occur?
In the membranous portion of the septum, but can occur at any point.
What happens to blood flow when a patent ductus arteriosus is present?
Blood flows from aorta to the pulmonary artery resulting in a constant mechanical murmur through systole and diastole (pressure in aorta is always greater).
What are the consequences of chronic left to right shunting?
Leads to vascular remodelling of the pulmonary circulation and an increase in pulmonary resistance.
Can lead to Eisenmenger Syndrome if the pulmonary resistance increases beyond the systemic resistance, so the shunt will reverse direction.
What is coarctation of the aorta?
Narrowing of the aortic lumen in the region of the ligamentum arteriosum. This increases the after load on the LV, leading to LV hypertrophy. Vessels to the head and upper limb are not compromised because they emerge proximal to coarctation.
In severe cases infants present with symptoms of heart failure.
Femoral pulses are weak and delayed with upper body hypertension.
What is tetralogy of fallot?
A group of 4 defects occurring together: VSD, overriding aorta, pulmonary stenosis and right ventricular hypertrophy. This results in R to L shunt. Deoxygenated blood mixes with oxygenated blood resulting in cyanosis.
Level of severity depends on severity of the pulmonary stenosis.
What is tricuspid atresia?
The lack of development of the tricuspid valve, leaving no inlet to the RV. There must be a complete R to L shunt of all blood returning to the RA (ASD or PFO) and a VSD or PDA to allow blood flow to the lungs.
What is transposition of the great arteries?
When the RV is connected to the aorta and the LV is connected to the pulmonary trunk. Results in two unconnected parallel circulations.
This is fatal unless there is a shunt for the two circulations to communicate. The ductus arteriosus can be maintained patent and/or an atrial septal defect formed.
What is a hypo plastic left heart?
When the left ventricle and ascending aorta fail to develop correctly. A PFO or ASD is also present and blood flow to systemic circulation is via patent ductus arteriosus. Lethal without surgical correction.
