Cardiovascular pathology Flashcards
What is the normal weight of the heart?
- 0.45% body mass (male)
- 280-340 g male
- 0.4% body mass (female)
- 230-280 g female
Describe contraction in the heart basically
- Two stage electrical generated contraction
- Sarcomere proteins
- Contraction initiated by depolarisation and changes to calcium concentration
- Protein conformational change – contraction
- Removal of calcium (energy dependent) for relaxation to occur
What are the 2 types of cardiac myocyte?
- Atrio-ventricular conduction system – slightly faster conduction
- General cardiac myocyte
What is the normal systolic ejection fraction?
60-60%
What is cardiac failure?
Failure to transport blood out of heart
What is severe failure?
Cardiogenic shock
When can myocardial hypertrophy be adaptive/physiology?
Athletes and pregnancy
What happens if you exceed stretch capability of sarcomeres?
cardiac contraction force diminishes
What is the hypertrophic response triggered by?
- Angiotensin 2
- ET-1 and insulin-like growth factor 1
- TGF-beta
Describe left sided cardiac failure
- Pulmonary congestion
- Heart is not able to pump efficiently so blood backs up in the veins that take blood through the lungs
- Pressure in these vessels increases and fluid is pushed into the alveoli and then overload of right side
Describe right sided cardiac failure
- Venous hypertension
- High pressure in the veins of the legs, caused by venous insufficiency where blood leaks downwards due to the effect of gravity through leaky valves
- And congestion
Describe diastolic cardiac failure
- Stiffer heart (left ventricle)
- A stiffer heart means the left ventricle cannot fill properly with blood during the diastolic phase, reducing the amount of blood pumped out to the body
Describe foetal embryogenesis
- Up until 5th week of gestation the heart is a single chamber, divided by the intra-ventricular
and intra-atrial septa from endocardial cushions - The muscular intra-ventricular septum grows upwards from the apex of the heart, producing the four chambers and allowing valve development to occur
What is congenital heart disease?
A general term for a range of birth defects that affect the normal way the heart works
What does congenital heart disease result from?
- Results from faulty embryonic development
- misplaced structures or arrest of the progression of normal structure development
What are the 4 most common congenital heart disease?
- VSD (ventricular septal defect) 25-30%
- ASD (atrial septal defect) 10-15%
- PDA (persistent/patent ductus arteriosus) 10-20%
- Fallots 4-10%
What is multifactorial inheritance?
One child with the defect increases the probability of second child with another defect
What are some disorders where single genes are affected?
trisomy 21, Turner Syndrome (XO)
How can infections cause congenital heart disease?
e.g. rubella – causes congenital heart disease in baby if pregnant mother develops rubella
What is a cardiac shunt?
A pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system
What are reasons left-right shunts occur?
- Ventricular septal defect
- Atrial septal defect
- Persistent ductus arteriosus
- Truncus arteriosus (a single blood vessel comes out of the right and left ventricles
What is anomalous pulmonary venous drainage?
blood flow from a few of the pulmonary veins return to the right atrium instead of the left atrium – some pulmonary venous flow enters the systemic venous circulation
What is hypoplastic left heart syndrome?
left side of the heart does not form correctly – underdeveloped left ventricle
What are reasons right-left shunts occur?
- Tetralogy of Fallot
- Tricuspid atresia – absence of tricuspid valve, underdeveloped right ventricle
What are defects that result in no shunt?
- Complete transposition of great vessels
- Coarctation
- Pulmonary stenosis
- Aortic stenosis
- Coronary artery origin from pulmonary artery
- Ebstein malformation/anomaly
- Endocardial fibroelastosis
What is complete transposition of great vessels?
an abnormal spatial arrangement of any of the great vessels
What is coarctation?
congenital narrowing of a short section of the aorta
What is pulmonary stenosis?
narrowing at a point from the right ventricle to the pulmonary artery causing obstruction of blood flow
What is aortic stenosis?
narrowing of the aortic valve opening restricting blood flow from the left ventricle to the aorta
What is Ebstein malformation/anomaly?
faulty tricuspid valve
What is endocardial fibroelastosis?
thickening within the muscular lining of the heart chambers due to an increase in the amount of supporting connective tissue, leading to cardiac hypertrophy
Describe Eisenmenger’s complex progression?
- Initially left-right shunt
- Then right-left shunting
- Associated with right side cardiac failure and right side cardiac
hypertrophy
What is patent foramen ovale?
A condition that occurs when the foramen ovale present before birth fails to close
What does patent foramen ovale eventually lead to?
- It eventually produces cardiac arrhythmias, pulmonary hypertension, right ventricular hypertrophy and cardiac failure
- There is also a risk of infective endocarditis
What is patent ductus arteriosus?
- The ductus arteriosus is a blood vessel connecting the pulmonary artery to the proximal descending aorta before birth
- It should usually occlude once the baby starts breathing
What is the consequence of ductus arteriosis?
- Left-right shunt eventually overloads the lung circulation with pulmonary hypertension and then right side cardiac failure
- There is also risk of infecting endocarditis
How can you close a patent ductus arteriosis?
It can be closed surgically, by catheters or by prostaglandin inhibitors
What are the 4 main features of tetralogy of fallot?
- Pulmonary stenosis
- Ventricular septal defect
- Dextroposition/ over-riding aorta (aorta straddles the VSD)
- Right ventricle hypertrophy
What does tetralogy of fallot lead to?
The right ventricle blood is shunted into the left heart, producing cyanosis from birth
How do you treat tetralogy of fallot?
Surgical correction usually required during first two years of life, as progressive cardiac debility and risk of cerebral thrombosis increases
What is cyanosis?
a bluish colour of the skin and the mucous membranes due to insufficient oxygen in the blood
What is ischaemic heart disease?
- Disease characterised by reduced blood supply to the heart
- The coronary arteries supply blood to the heart so a blockage reduces the supply of blood to the heart muscle