Cardiology - Coarctation of the Aorta, TGA & Tetralogy of Fallot Flashcards
What is coarctation of the aorta?
A congenital condition where there is narrowing of the aortic arch (or descending aorta).
Narrowing of the aorta reduces the pressure of blood flowing to the arteries that are distal to the narrowing. It increases the pressure in areas proximal to the narrowing, such as the heart and the first three branches of the aorta.
Where does coarctation of the aorta usually occur around?
The ductus arteriosus.
What condition is coarctation of the aorta often associated with?
Turners syndrome
What are 4 conditions that coarctation of the aorta is associated with?
1) Turner’s syndrome
2) Bicuspid aortic valve
3) Berry aneurysms
4) Neurofibromatosis
Is coarctation of the aorta more common in males or females?
Males (despite an association with Turner’s syndrome).
Often, what is the only indication of coarctation of the aorta in neonates?
Weak femoral pulses.
How will coarctation of the aorta affect BP?
Perform a four limb BP:
1) High BP in limbs supplied from arteries that come before the narrowing
2) Lower BP in limbs that come after the narrowing
What type of BP should be performed in coarctation of the aorta?
Four limb BP
Exam findings in coarctation of aorta in infancy?
1) Weak femoral pulses
2) Four limb BP findings
3) Systolic murmur: heard below the left clavicle (left infraclavicular area) and below the left scapula
4) Tachypnoea and increased work of breathing
5) Poor feeding
6) Grey and floppy baby
7) Radio-femoral delay
What additional 3 signs of coarctation of aorta may develop over time?
1) Left ventricular heave due to left ventricular hypertrophy
2) Underdeveloped left arm where there is reduced flow to the left subclavian artery
3) Underdevelopment of the legs
What key sign is seen in adults in coarctation of the aorta?
HTN
Management of coarctation of aorta?
Mild - patients can live symptom free until adulthood
Severe - emergency surgery shortly after birth.
What is there a risk of in cases of critical coarctation?
Risk of heart failure and death shortly after birth.
What is given in cases of critical coarctation that require emergency surgery?
Prostaglandin E –> used to keep the ductus arteriosus open while waiting for surgery
Purpose of Prostaglandin E in severe coarctation of aorta cases?
Used keep the ductus arteriosus open while waiting for surgery.
This allows some blood flow flow through the ductus arteriosus into the systemic circulation distal to the coarctation.
Surgical management of coarctation of aorta?
Surgery is performed to correct the coarctation and to ligate the ductus arteriosus.
What does transposition mean?
In each others place
What are the great arteries?
1) The pulmonary artery
2) The aorta
What is transposition of the great arteries (TGA)?
A type of congenital heart defect where the attachments of the aorta and the pulmonary trunk to the heart are swapped (“transposed”).
This means the right ventricle pumps blood into the aorta and the left ventricle pumps blood into the pulmonary vessels.
Is TGA cyanotic or acyanotic?
Usually acyanotic.
This is due to there being two separate circulations that don’t mix: one travelling through the systemic system and right side of the heart and the other traveling through the pulmonary system and left side of the heart.
What is the hallmark of TGA?
Ventriculoarterial discordance
This is when the aorta arises from the morphologic right ventricle and the pulmonary artery arises from the morphologic left ventricle
In the majority of patients (60%) with TGA, where is the aorta in relation to the pulmonary artery?
What is this called?
The aorta is anterior and to the right of the pulmonary artery (dextro-transposition of the great arteries [d-TGA]).
What are the 2 possible classifications of TGA?
1) Dextro-transposition of the great arteries [d-TGA]) –> the aorta is anterior and to the right of the pulmonary artery
2) Levo-transposition of the great arteries [l-TGA]) –> the aorta may be anterior and to the left of the pulmonary artery
What is the most common cause of cyanosis in the new born?
TGA
Is TGA more common in males or females?
Males (60-70%)
Describe what happens in dextro-TGA
The pulmonary and systemic circulation run in parallel, causing oxygenated blood to recirculate only in the pulmonary circulation and deoxygenated systemic blood to bypass the lungs.
This results in cyanosis unless there is mixing of oxygenated blood and deoxygenated blood.
What are 3 common anatomic sites for mixing of oxygenated and deoxygenated blood in TGA that allows life to be sustained?
1) Patent foramen ovale or atrial septal defect
2) Ventricular septal defect
3) Patent ductus arteriosus
What happens in levo-TGA [also called as CC-TGA]?
The ventricles have switched places as opposed to the arteries.
This is acyanotic as deoxygenated blood can return from the systemic circulation and enter the pulmonary circulation to be oxygenated before entering the systemic circulation again.
Which type of TGA can be acyanotic?
Levo-TGA [also called as CC-TGA].
However, the right ventricle and tricuspid valve is not accustomed to the higher pressures of the left side of the heart. There is hypertrophy over time, which can result in tricuspid regurgitation and heart failure.
What are the maternal risk factors for TGA?
1) Age >40 y/o
2) Maternal diabetes
3) Rubella
4) Poor nutrition
5) Alcohol consumption
When is TGA often diagnosed?
During pregnancy with antenatal ultrasound scans.
Presentation of TGA?
1) Cyanosis: at birth or within 24 hours (if no mixing at the atrial level)
2) Mild cyanosis (particularly when crying) might be evident)
3) Signs of congestive heart failure may appear over first 3-6 weeks:
- tachypnoea
- sweating
- poor feeding
- failure to gain weight
How can some patients with TGA initially compensate at birth?
A patent ductus arteriosus or ventricular septal defect can initially compensate by allowing blood to mix between the systemic circulation and the lungs.
Examination findings in TGA?
1) Prominent right ventricular heave
2) Single second heart sound, loud A2
3) Systolic murmur potentially if VSD present
4) No signs of respiratory distress
Management of TGA?
1) Emergency prostaglandin E1 infusion –> to keep the ductus arteriosus patent as a temporary solution that allows mixing of blood
2) Correct metabolic acidosis
3) Emergency atrial balloon septostomy to allow for mixing
4) Definitive –> surgical correction
Definitive investigation in TGA?
Echo
What is a typical CXR finding in TGA?
“Egg on a string” due to potentially narrowed upper mediastinum; cardiomegaly and increased pulmonary vascular markings
Purpose of Prostaglandin E1 in TGA?
Keeps the ductus arteriosus patent as a temporary solution that allows mixing of blood.
What is the surgical management of TGA?
A cardiopulmonary bypass machine is used to perform an “arterial switch” procedure within a few days of birth. If present, a VSD or ASD can be corrected at the same time.
What is a balloon septostomy?
Why may it be indicated in TGA?
Balloon septostomy involves inserting a catheter into the foramen ovale via the umbilicus, and inflating a balloon to create a large atrial septal defect.
This allows blood returning from the lungs (on the left side) to flow to the right side of the heart and out through the aorta to the body.
What is the most ommon cyanotic congenital heart disease (CHD) presenting after the neonatal period?
Tetralogy of Fallot (TOF)
What does ‘tetralogy’ mean?
Refers to something made up of four parts.