Cardiology Flashcards
In a fetus where does the blood get oxygenated?
At the placenta
Why does it not make sense for the feotal blood to pass through the pulmonary circulation.
As the fetal lungs are not fully developed or functional
What are the 3 feotal shunts
Ductus venosus: This shunt connects the umbilical vein to the inferior vena cava and allows blood to bypass the liver.
Foramen ovale: This shunt connects the right atrium with the left atrium and allows blood to bypass the right ventricle and pulmonary circulation.
Ductus arteriosus. This shunt connects the pulmonary artery with the aorta and allows blood to bypass the pulmonary circulation.
Why does the foramen ovale close at birth?
The first breaths the baby takes expands the alveoli, decreasing the pulmonary vascular resistance. The decrease in pulmonary vascular resistance causes a fall in pressure in the right atrium. At this point the left atrial pressure is greater than the right atrial pressure, which squashes the atrial septum to cause functional closure of the foramen ovale
What is required to keep the ductus arteriosus open.
Prostaglandins
What causes closure of the ductus arteriosus, which becomes the ligamentum arteriosum.
Increased blood oxygenation causes a drop in circulating prostaglandins.
What causes the ductus venosus to close
Immediately after birth the ductus venosus stops functioning because the umbilical cord is clamped and there is no flow in the umbilical veins.
What does the ductus venosus become?
The ductus venosus structurally closes a few days after birth and becomes the ligamentum venosum.
What murmurs are common to hear in children?
Innocent murmurs are also known as flow murmurs. They are very common in children. They are caused by fast blood flow through various areas of the heart during systole.
What are innocent murmurs heard as?
Soft Short Systolic Symptomless Situation dependent, particularly if the murmur gets quieter with standing or only appears when the child is unwell or feverish
How do you investigate a murmur ?
ECG
Chest Xray
Echocardiography
What are the types of pan-systolic murmurs and where are they heard?
Mitral regurgitation heard at the mitral area (fifth intercostal space, mid-clavicular line)
Tricuspid regurgitation heard at the tricuspid area (fifth intercostal space, left sternal border)
Ventricular septal defect heard at the left lower sternal border
What are the ejection systolic murmurs and where are they heard?
Aortic stenosis heard at the aortic area (second intercostal space, right sternal border)
Pulmonary stenosis heard at the pulmonary area (second intercostal space, left sternal border)
Hypertrophic obstructive cardiomyopathy heart at the fourth intercostal space on the left sternal border
Why can the second heart sound sometimes be split?
When breathing in there is a negative intra-thoracic pressure. This causes the right side of the heart to fill faster as it pulls in blood from the venous system. This increases the filling of the right side causing a delay in the pulmonary valve closing. When the pulmonary valve closes slightly later than the aortic valve, this causes the second heart sound to be “split”.
What does an ASD cause?
mid-systolic, crescendo-decrescendo murmur loudest at the upper left sternal border, with a fixed split second heart sound.
This is because blood is flowing from the left atrium into the right atrium across the atrial septal defect, increasing the volume of blood that the right ventricle has to empty before the pulmonary valve can close.
What does a PDA cause?
a continuous crescendo-decrescendo “machinery” murmur that may continue
What does ToF cause?
pulmonary stenosis, giving an ejection systolic murmur loudest at the pulmonary area (second intercostal space, left sternal border).
How does a cyanotic heart disease arise?
This occurs across a right-to-left shunt. A right-to-left shunt describes any defect that allows blood to flow from the right side of the heart to the left side of the heart.
What heart defects can cause a right to left shunt?
Ventricular septal defect (VSD)
Atrial septal defect (ASD)
Patent ductus arteriosus (PDA)
Transposition of the great arteries
Why are patients with VSD, ASD and PDA not usually cyanotic?
because the pressure in the left side of the heart is much greater than the right side, and blood will flow from the area of high pressure to the area of low pressure.
What is Eisenmenger syndrome.
pulmonary pressure increases beyond the systemic pressure blood will start to flow from right-to-left across the defect, causing cyanosis
Patients with transposition of the great arteries will always have…
cyanosis because the right side of the heart pumps blood directly into the aorta and systemic circulation.
Why does the PDA sometimes fail to close?
reasons why it fails to close are unclear, but it may be genetic or related to maternal infections such as rubella. Prematurity is a key risk factor.
What can PDA lead to in adult life?
Heart failure if it is undiagnosed in early life.
