Pathophysiology (cardiovascular system)

Question 1

At what point in gestation does the foetus develop a heart beat?

Answer 1

Day 23

Question 2

How do the foetus’ heart structures change at birth?

Answer 2

Foramen ovale- at birth, the lungs open up and the pulmonary blood pressure falls into the heart via the pulmonary veins increasing the pressure in the left atrium, which closes the septal wall that formed the foramen ovale

Ductus arteriousis
-before birth, any blood entering the pulmonary artery would transfer across the ductus arterioles into the aorta
-after birth, this duct is not needed and starts to close as oxygen saturation increase

Ductus venosus
-before birth, this allows oxygenated blood from the placenta to flow from the umbilical vein through the duct bypassing the liver to enter the inferior vena cava
-after birth, this is no longer used and it closes

Question 3

What are the possible causes of congenital cardiac conditions?

Answer 3

1. environmental factors- if mother is exposed to a drug or chemicals, infections or physical agents there can be a risk of the unborn baby developing a cardiac or cardiovascular condition
2. maternal illness- mothers with insulin dependent diabetes mellitus have a 5x greater risk of babies being born with cardiac anomalies
3. genetics- chromosomal changes or mutations may increase risk of developing a cardiac anomaly.

Question 4

When are congenital cardiac conditions usually diagnosed?

Answer 4

-at the 20 week scan will usually show any major heart abnormality
-can be babies present in either the first week with cyanosis or 8-10 days old as the ductus arterioles closes fully

Question 5

What is the congenital cardiac condition patent ductus arteriosus?

Answer 5

-a blood vessel connecting the aorta to the pulmonary artery, allowing blood to bypass the lungs present in the foetus, but should close naturally itself
-not cyanosed

Question 6

What is the congenital cardiac condition atrioventricular septal defect?

Answer 6

-a hole in the centre of the heart allowing blood to flow between all 4 chambers
-cyanosed

Question 7

What is the congenital cardiac condition atrial septal defect?

Answer 7

-develops when the foramen ovale does not close at birth so a hole connects the atria
-not cyanosed because the pressure of blood flow is higher on the left side of the body

Question 8

What is the congenital cardiac condition ventricular septal defect?

Answer 8

-there is a hole between the right and left ventricle, allowing for the mixing of blood
-cyanosed

Question 9

What is the congenital cardiac condition coarctation of the aorta?

Answer 9

-narrowing in part of the aorta which causes the left side of the heart to work harder

Question 10

What is the congenital cardiac condition truncus arteriosus?

Answer 10

-A single large blood vessel leaves the heart instead of two separate vessels, allowing the mixing of blood (ventricular septal defect)
=cyanosed

Question 11

What is the congenital cardiac condition transposition of the great vessels?

Answer 11

-the aorta and pulmonary arteries are switched, reversing the position of the two main blood vessels that carry blood away from the heart
-cyanosed

Question 12

What is the congenital cardiac condition Tetralogy of Fallot?

Answer 12

-when 4 structural abnormalities develop together, they include
-atrioventricular septal defect
-ventricular septal defect
-overriding aorta
-right ventricle myocardium thickened

-cyanotic

Question 13

What is the congenital cardiac condition pulmonary valve stenosis ?

Answer 13

pulmonary valve narrows, making it harder for blood to flow from the heart to the lungs

Question 14

When does heart failure occur?

Answer 14

-when the heart fails to pump blood effectively around the body
-two main types are failure of the pump and overloading of the heart

Question 15

What are the possible causes of heart failure?

Answer 15

-congential heart disease
-heart valve disease
-conduction (ECG) problems
-infections e.g endocarditis, myocarditis, pericarditis
-rheumatic disease
-muscular dystrophy
-medications (e.g for cancer)

Question 16

What is the physiology behind heart failure?

Answer 16

-the mechanism in developing heart failure is similar to adults in that the cause triggers a reduction in the ability of the myocardium to contract, reducing cardiac output

-the brain responds to the lower cardiac output by:
-activating the sympathetic nervous system- increases heart beat
-activating the RAAS- hormones increases blood volume by reducing urine output