Cardiology Flashcards
(83 cards)
What are the 3 foetal shunts ?
Ductus venosus - bypass liver
Foramen ovale - right atrium to left atrium
Ductus arteriosus - bypass pulmonary circulation
What happens to the foramen ovale at birth ?
The first breaths the baby takes expand the alveoli decreasing pulmonary vascular resistance. This causes a fall in right atrial pressure. This causes the left atria to have a higher pressure which causes the closure of the foramen ovale. This then becomes the fossa ovalis.
How does the ductus arteriosus close at birth ?
Prostaglandins are required to keep the ductus arteriosus open. Increased blood oxygenation causes a drop in circulating prostaglandins causing it to close. This then forms the ligamentum arteriosum.
How does the ductus venosus close at birth ?
Immediately after birth it stops functioning as the umbilical cord is clamped and there is no flow in the umbilical veins. It then structurally closes a few days later and becomes the ligamentum venosum.
What are some features indicating an innocent murmur ?
Soft
Short
Systolic
Symptomless
Situation dependent
what are some features of a murmur that would require a follow up from a paediatric cardiologist ?
Murmur louder than 2/6
Diastolic murmur
Louder on standing
Other symptoms - failure to thrive, cyanosis, feeding difficulty and shortness of breath
What investigations are required for a murmur ?
ECG
CXR
Echocardiology
What are some pan-systolic murmurs and where are they heard loudest ?
Mitral regurgitation - mitral valve ( fifth intercostal space, mid clavicular line )
Tricuspid regurgitation - tricuspid area ( fifth intercostal space, left sternal border )
Ventricular septal defect - left lower sternal border
What are some ejection-systolic murmurs and where are they heard loudest ?
Aortic stenosis - aortic area ( second intercostal space, right sternal border )
Pulmonary stenosis - pulmonary area ( second intercostal space, left sternal border )
What murmur is head in a an atrial septal defect ?
Mid systolic crescendo decrescendo murmur heard loudest at the upper left sternal border
Why is there a fixed split second heart sound ?
This occurs because blood is flowing from the left atrium into the right across the defect. This increases the volume of blood that the right ventricle has to empty before the pulmonary valve can close.
What causes splitting of the second heart sound ?
During inspiration the chest walls and diaphragm pull the lungs open. This also pulls the heart open. This is called negative intra-thoracic pressure. This causes the right side of the heart to fill faster as it pulls in blood from the venous system. The increased volume causes it to take longer to empty during systole. This causes the pulmonary valve to close slightly later than the aortic valve causing the split.
What murmur is heard in tetralogy of fallot ?
Ejection systolic murmur loudest at the pulmonary area
The murmur is due to the pulmonary stenosis
When does cyanosis occur in heart disease ?
When deoxygenated blood enters the systemic circulation. This occurs when the blood is able to bypass the pulmonary circulation and the lungs. - right to left shunt.
What heart defects cause a left to right shunt and therefore cyanosis ?
Ventricular septal defect
Atrial septal defect
Patent ductus arteriosus
Transposition of the great arteries
What is the pathophysiology of patent ductus arteriosus ?
The pressure in the aorta is higher than that in pulmonary vessels so blood flows from the aorta to the pulmonary artery. This creates a left to right shunt. This increases pressure in the pulmonary vessels causing hypertension. This increases the pressure for the right side of the heart causing right ventricular hypertrophy.
What is the presentation of patent ductus arteriosus ?
SOB
Difficulty feeding
Poor weight gain
Lower respiratory tract infections
When can patent ductus arteriosus be picked up ?
During the newborn examination if the murmur is heard.
What is the murmur heard in patent ductus arteriosus ?
Continuous crescendo - decrescendo ‘machinery’ murmur
What investigations are performed when suspecting patent ductus arteriosus ?
Echocardiogram
( Doppler flow )
What is the management of patent ductus arteriosus ?
Monitored until 1 years old using echo
Highly likely after 1 year it closes by itself
or
Trans-catheter or surgical closure
What is an atrial septal defect ?
A defect ( hole ) in the septum between the two atria. This connects the right and left atria allowing blood to flow between them.
How does an atrial septal defect occur ?
A defect in the development of the septum between the atria occurs causing a hole to develop connecting the left and right atria.
How does pulmonary hypertension occur from an atrial septal defect ?
An ASD leads to a shunt with blood moving between the two atria. Blood moves from the left atrium to the right. This means blood continues to flow to pulmonary vessels and lungs to get oxygenated and the patient does not become cyanotic. However the increased flow leads to right heart strain and overload. This strain can lead to right heart failure and pulmonary hypertension.