Cardiovascular Pathology 2 Flashcards
What is the definition of heart failure / congestive cardiac failure (CCF)?
Inability of the heart to pump enough blood needed to meet the metabolic demands of the tissue
it can occur insidiously or suddenly
What causes heart failure to occur insidiously or suddenly?
Insidious:
- cumulative effects of chronic workload
- hypertension and valve diseases
Sudden:
- acute haemodynamic stress
- fluid overload and large myocardial infarction
What are the three categories that can cause increased cardiac work?
- Hypertension causes pressure overload
- valvular disease causes pressure and/or volume overload
- myocardial infarction causes regional dysfunction with volume overload
What does an increase in cardiac work lead to?
Increased cardiac work leads to increased wall stress
this leads to cell stretch (enhanced contractility - Frank-Sterling mechanism)
this leads to hypertrophy and/or dilation
what is hypertrophy and/or dilation characterised by?
- Increased heart size & mass
- increased protein synthesis
- induction of immediate-early genes
- induction of fetal gene program
- abnormal proteins
- fibrosis
- inadequate vasculature
what does hypertrophy and/or dilation lead to?
Cardiac dysfunction
(left-sided heart failure)
what is cardiac dysfunction characterised by?
- Heart failure (systolic / diastolic)
- arrhythmias
- neurohumoral stimulation
what is meant by neurohumoral stimulation in cardiac dysfunction?
Release of norepinephrine:
- increases heart rate and myocardial contractility
activation of renin-angiotensin-aldosterone system:
- adjusts fluid volume
release of atrial natriuretic peptides:
- Adjusts fluid volume
What are other causes of CCF that cause increased cardiac work?
- Hyperthyroidism
- beriberi
- anaemia
- congenital heart diseases
What are the clinical effects of left sided heart failure due to?
- Low cardiac output and hypoperfusion of tissues
- pulmonary congestion
What are the symptoms of left heart failure (congestion)?
- Dyspnea
- orthopnea
- paroxysmal nocturnal dyspnea (PND)
- blood tinged sputum
- cyanosis
- elevated pulmonary “wedge” pressure (PCWP)
what are the consequences of left sided failure producing a low cardiac output?
There is reduced kidney perfusion
- pre-renal azotemia
- renin-angiotensin-aldosterone activation
- salt and fluid retention leads to expansion of interstitial and intravascular fluid volume
What can advanced cardiac failure lead to?
Cerebral hypoxia
this is characterised by irritability, restlessness, stupor and coma
what is the aetiology of right sided heart failure?
What are the symptoms and signs due to?
Aetiology involves left heart failure & cor pulmonale
How does right sided heart failure affect the liver/spleen and pleura/pericardium?
Liver & spleen (portal congestion):
- Passive congestion (nutmeg liver)
- congestive splenomegaly
- ascites
- congestion and oedema of bowel wall
Pleura / pericardium (systemic venous congestion):
- pleural and pericardial effusions
- transudates
- oedema of peripheral and dependent parts of body
what are the 2 main categories of problems in valvular heart disease?
Problems with opening the valves - stenosis
problems with closing the valves - regurgitation
(or incompetence or “insufficiency”)
What is stenosis and what does it lead to?
What usually causes it?
It is the failure of the valve to open completely, impending forward flow
leads to pressure overload of the heart
almost always due to chronic abnormality of valvular leaflet caused by relatively few disorders
What causes regurgitation and what does it lead to?
What is it?
It is failure of the valve to close completely, allowing reverse flow
leads to volume overload of the heart
can result from intrinsic disease of the valve cusps or damage to the supporting structures
it has many causes and may appear acutely or chronically
What are the 2 different types of valvular abnormalities?
Congenital and acquired
What 2 conditions account for 70% of all valvular heart disease?
- Acquired aortic stenosis
- Acquired mitral stenosis
(rheumatic heart disease)
What is acquired aortic stenosis and what age group tends to be affected by it?
Calcification of a deformed (congenitally bicuspid) valve
tends to affect 50-70 year olds
or “senile” calcification of an anatomically normal aortic valve in the >70 age group
what is the prevalence of calcific aortic stenosis?
What is it the consequence of?
It is the most common valvular abnormality with a 2% prevalence, rising with increasing life expectancy
it is usually the consequence of age-related wear and tear of a normal valve or congenital bicuspid aortic valve3
the bicuspid aortic valve undergoes more mechanical stress so becomes stenotic earlier
What factors are involved in the pathogenesis of calcific aortic stenosis?
How is the mitral valve affected?
There is a role for hyperlipidaemia, hypertension and inflammation in pathogenesis
(factors also implicated in atherosclerosis)
mitral valve is generally normal but can be involved by extension of calcific deposits
What are the features of aortic stenosis?
- 2X gradient pressure
- left ventricular hypertrophy & ischaemia (but no hypertension)
- cardiac decompensation
- angina
- chronic heart failure
What are the survival rates like for aortic stenosis?
50% die in 5 years if angina is present
50% die in 2 years if chronic heart failure is present
What is rheumatic heart disease the result of?
What are its 3 defining features?
It follows a group A streptococcus infection, a few weeks later
it involves pancarditis
- Endocarditis
- Myocarditis
- Pericarditis
What are the features of acute rheumatic heart disease?
- Inflammation
- aschoff bodies
- antischkow cells
- pancarditis
- vegetations on chordae tendinae at leaflet junction
what are the features of chronic rheumatic heart disease?
- Thickened valves
- commisural fusion
- thick, short chordae tendinae
Which valve is always involved in rheumatic heart disease?
Mitral valve is always involved
MV affected alone in 70% of cases
MV and AV in 25% of cases
TV and PV are rarely involved
What criteria is used for acute rheumatic fever?
Jones criteria
evidence of preceding streptococcal infection
+ 2 major manifestations
or 1 major + 2 minor manifestations
what are the major and minor manifestations of acute rheumatic fever?
Major manifestations:
- migratory polyarthritis
- pancarditis - pericardial frictional rub, weak heart sound, arrhythmias
- subcutaneous nodules
- erythema marginatum of skin
- sydenham chorea
What are the minor manifestations of acute rheumatic fever?
- Fever
- arthralgia
- elevated acute phase proteins in the blood
What are the clinical features of chronic rheumatic heart disease?
What are they dependent on?
- Cardiac murmurs
- cardiac hypertrophy and dilation
- arrhythmias
- cardiac failure
- thromboembolic complications
- infective endocarditis
these features appear many years after initial episode of rheumatic fever
it depends on which cardiac valve is involved
What are the differences between aortic and mitral valve regurgitations?
Aortic regurgitation:
- rheumatic
- infectious
- aorti dilatations
- syphylis
- rheumatoid arthritis
- marfan syndrome
mitral regurgitation:
- MVP
- infectious
- Fen-Phen
- papillary muscles, chordae tendinae
- calcification of mitral ring (annulus)
what is mitral valve prolapse (MVP)?
What causes it?
Myxomatous degeneration of the mitral valve
the valve becomes “floppy”
cause is unknown in most cases, but it is associated with connective tissue disorders (marfan syndrome)
What is the incidence of mitral valve prolapse like?
How can it be identified?
3% incidence, more common in females than males
it is easily seen on echocardiogram
How can mitral valve prolapse be identified here?
- Attenuation of collagenous fibrosa layer (far left)
- thickened spongiosa layer containing mucoid deposits (myxomatous degeneration)
What is meant by myxomatous degeneration?
Connective tissue disorder characterised by thickening and elongation of mitral leaflets and chordae tendinae and by dilation of the mitral annulus
What are the clinical features of mitral valve prolapse?
It is usually asymptomatic
- mid-systolic “click”
- holosystolic murmur if regurgitation is present
- occasional chest pain, dyspnea
97% have no untoward effects
3% have infective endocarditis, mitral insufficiency, arrhythmias, sudden death
What it mitral annular calcification?
Who tends to be affected?
Degenerative calcification of the mitral “skeleton” (annulus)
it typically affects >60s and is more common in females
What are the signs and symptoms of mitral annular calcification?
There is usually no dysfunction
there is usually regurgitation, but stenosis is possible
What are the more severe outcomes of mitral annular calcification?
Arrhythmias and sudden death
this is due to deep penetration of calcium deposits impinging on atrioventricular conduction system
increased risk of infective endocarditis and emboli stroke from dislodged overlying thrombi
What is meant by congenital heart defects?
What causes them and what is the incidence like?
Abnormalities of the heart and great vessels present from birth
(may not be evident until adult life)
due to faulty embryogenesis (week 3-8)
they are usually monomorphic (single lesion) and affect around 1% of births
What are the different congenital heart defects?
What is the D and T method of remembering these?
- Ventricular septal defect
- atrial septal defect
- pulmonary stenosis
- patent ductus arteriosus
- Tetralogy of Fallot
- coarctation of aorta
- atrioventricular septal defect
- transposition of great arteries
- truncus arteriosus
- total anomalous pulmonary venous connection
- tricuspid atresia
highlighted D = L -> R shunt
highlighted T = R -> L shunt (cyanosis)
What are sporadic genetic abnormalities the main cause of?
They are the main known cause of congenital heart diseases
gene abnormalities are present in 10% of CHD cases
What are sporadic genetic abnormalities seen in congenital heart diseases?
Trisomies:
- 21, 13, 15 and 18
- also monosomy XO in Turner syndrome
mutations of genes encoding transcription factors:
- TBX5 - atrial / ventricular septal defects
- NKX2.5, GATA4 - atrial septal defects
deletion of chromosome 22q11.2:
- conotruncus
- abnormal development of thymus and parathyroid (DiGeorge syndrome)
What are the environmental factors that influence congenital heart defects?
- Rubella (congenital rubella syndrome)
- gestational diabetes
- teratogens
What is the result of having a L to R shunt in congenital heart disease?
All “Ds” in their names
there is NO cyanosis
there is pulmonary hypertension
significant pulmonary hypertension is irreversible
What is the result of having a R to L shunt in congenital heart disease?
All “Ts” in their names
results in cyanosis (“blue” babies)
venous emboli become systemic “paradoxical”
What types of congenital heart disease cause obstructions?
- Coarctation of aorta
- aortic / pulmonary valve stenosis
What is the most feared consequence of L to R shunts?
What conditions produce this?
Irreversible pulmonary hypertension is the most feared consequence
- atrial septal defects
- ventricular septal defects
- atrioventricular septal defects
- patent ductus arteriosus
What is an atrial septal defect?
What symptoms do they have?
Abnormal fixed opening in atrial septum caused by incomplete tissue formation that allows communication of blood between the left and right atria
(NOT patent foramen ovale)
they are usually asymptomatic until adulthood and mortality is low following repair
How are atrial septal defects classified?
They are classified according to their location
secundum:
- 90% of ASDs
- defective fossa ovalis (near centre of atrial septum)
primum:
- 5% of ASDs
- adjacent to AV valves, mitral cleft
sinus venosus:
- 5% of ASDs
- near entrance of SVC with anomalous pulmonary veins draining to SVC or RA
When do ventricular septal defects tend to occur?
Most common congenital heart disease defect
30% of these occur in isolation
they usually occur with tetralogy of fallot
How are VSDs classified?
According to size and location
membranous VSD:
- 90% involve the membranous septum
infundibular VSD:
- 10% involve the muscular septum or lie below the pulmonary valve
- if muscular septum is involved, there can be multiple holes (“Swiss-cheese” septum)
What happens to small and large ventricular septal defects?
Small ones often close spontaneously
large ones progress to pulmonary hypertension
what is shown in this image?
Membranous type ventricular septal defect
What are the 5 different congenital abnormalities which cause a right to left shunt?
- Tetralogy of Fallot
- Transposition of great arteries
- Truncus arteriosus
- Total anomalous pulmonary venous connection
- Tricuspid atresia
(all start with T)
what are the 4 components of Tetralogy of Fallot?
why does it occur?
- Large ventricular septal defect
- obstruction of right ventricle outflow tract (subpulmonary stenosis)
- aorta overrides the VSD
- right ventricular hypertrophy
occurs due to anterosuperior displacement of the infundibular septum during embryogenesis
What does survival depend on in tetralogy of Fallot?
What is a “pink” tetralogy?
Survival depends on severity of subpulmonic stenosis
classical TOF is a cyanotic congenital heart disease
a “pink” tetralogy occurs if the subpulmonic obstruction is small
the greater the obstruction, the greater the R –> L shunt
what 3 conditions can be referred to as obstructive chronic heart disease?
- Coarctation of the aorta
- pulmonary stenosis / atresia
- aortic stenosis / atresia
Who tends to be affected by coarctation of the aorta?
It affects more males than females (2:1)
commonly seen in females with Turner syndrome (XO)
a bicuspid aortic valve is present 50% of the time
what is meant by the infantile form of coarctation of the aorta?
This is proximal to PDA and is very serious
there is shunting of deoxygenated blood via patent ductus arteriosus (PDA), producing cyanosis in the lower half of the body
What is meant by the adult form of coarctation of the aorta?
Why is this not as serious as the infantile form?
What sign might be visible?
The ductus arteriosus is closed, rather than patent
typically hypertension in the upper extremities and hypotension / weak pulses in lower extremities and features of arterial insufficiency (claudication / coldness)
development of collateral circulation between pre-coarctation arterial branches and post-coarctation arteries through enlarged intercostal and internal mammary arteries causes visible erosions (notching) of the undersurface of the ribs
