BIOMED
Pathophysiology
Everything be alphabetical here (except for Homeostasis at the bottom) 😘
(& Mental Health, Lmao)
There are a lot of neonatal conditions covered, seen in high level NICU/NCCU Units.
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Table of Contents:
1 | Ageing
2 | Canc...
In coarctation of the aorta, we have a narrowed short segment (juxtaductal aorta) just beyond the first split of the aorta where the head and arms arteries stem from. Coatction is often discovered in the first few weeks of life depending on the degree of juxaductal aorta narrowing.
Coarctation may be caused by excess ductal tissue present related to the fetal ductus arteriosus. This tissue in its wall helps to close the ductus.
Further, babies with coarctation may have a hypoplastic (small) aorta or other cardiac defects, most usually involving the left side of the heart. These common coexisting defects include the bicuspid aortic valve and ventricular septal defect (see VSD chap for more info), as well as single ventricle heart defects such as Hypoplastic Left Heart Syndrome (see HLHS chap for more info).
In coarctation, the left ventricle has to work harder to create greater pressure to force blood through the narrow aortic segment, as—keeping in mind—things flow from areas of higher to lower pressure. Therefore, if the coarctation is severe enough, the ventricle may not be able to achieve this, leading to congestive heart failure and respective hypoxia and cyanosis.
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Diagnosis & Symptoms 25% of isolated coarctation is severe enough to show symptoms in the first days of life as the ductus arteriosus closes and the left ventricle is forced to pump against a far higher resistance. This can lead to heart failure and shock, and as babies are okay until their ductus closes, symptoms come on quickly and are often severe. If this is not the case however, it can be years before a heart murmur or blood pressure is discovered, and thus, investigations are begun.
When pulses in a child's legs are unable to be palpated, but there is a high blood pressure int he arms, coarctation is suspected (as the coarctation occurs in the juxtaductal aorta after the upper extremity arteries stem off.
This diagnosis is confirmed by echocardiography to look at the anatomy of the aorta and assess for other abnormalities.
MRI or CT Scans may be used in addition to look at the coarctation.
Treatment In critically unwell newborns, goals are to improve ventricular function to improve blood flow to the lower extremities and stabilise the child. Prostaglandin E is administered to keep the ductus arteriosus open and allow blood flow beyond the point of the coarctation. Other IV medications may be administered to help support the heart, and many babies will go onto ventilators prior to surgery.
There are a few surgical treatment options to repair coarctation, most commonly removing (resection) of the stenosis and anastomosis (reconnection) of the arteries either side of the removed coarctation. This may be extended towards the arch if necessary, or alternatively, the narrowing may be opened with a patch, or a portion of an artery to expand the area (subclavian flap aortaplastly).
Complications as a result of these surgeries include damage to kidneys or spinal cord due to the aorta being clamped during surgery. In 10-20% of patients there will be restenosis (return of the coarctation), however this rate decreases in older children.
Further complications include hypertension seen in infants treated by medicines, and there is a potent ion to develop aneurysms at the site of repair. MRI or CT scans will be completed in follow up cardiology management as they age to monitor for these.
Management Into Adulthood These patients will require long-term follow up with cardiology to monitor for complications, and these will include physical exam and periodic ECGs and echocardiograms. Cardiac MRI or CT may be used in larger/older patients.
There is a likelihood that patients will need to go onto hypertensives, or receive a stent or other procedure to prevent this, and it is important to note that patients usually have a bicuspid aortic valve that may break down over time. Thee patients will alto tend to develop aneurysms of their ascending aorta.
Overall however, these patients of coarctation generally do well with additional treatment to protect their long-term health.
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