CARDIO Flashcards
Most common congenital heart disease
septal defects
types of congenital heart disease
right to left shunt
left to right shunt
obstructions
examples of right to left shunt
tetralogy of fallot (most common), transposition of great arteries
4 anatomical features of tetralogy of fallot
- ventricular septal defect (communication between RV and LV)
- obstruction to the RV outflow (pulmonary stenosis)
- over-riding aorta (above septal defect)
- RV hypertrophy (due to volume and pressure overload due to septal defect)
in the tetralogy of fallot, what factor determines the direction of the shunt
the obstruction to the RV outflow - severity of this dictates shunt direction.
Mild: L –> R
Critical: R –> L
Transposition of great arteries
anatomical discordance such that the aorta arises from the RV and the pulmonary artery emanates from the LV.
Shunt means better prognosis as there is some mixing of blood.
define right to left shunt and what it is clinically characterised as
when deoxy blood form right side of heart mixes with the left. Clinically characterised as cyanosis, since the cells of the body are receiving poorly oxygenated blood.
what is cyanosis often accompanied by
clubbing of fingers and toes
define shunt
abnormal connection between heart chambers leading to abnormal blood flow.
examples of left to right shunts
atrial septal defect, ventricular septal defect, patent ductus arteriosis
consequences of left to right shunts
increased pulmonary blood flow which causes increased pressure and volume in pulmonary circulation. this causes pulmonary hypertension and RV hypertrophy.
how does pulmonary artery response to increase pressure and volume associated with left to right shunts
vasoconstriction and resistance eventually causes the shunt to shift from a left to right shunt to a right to left shunt with associated cyanosis
atrial septal defect is an example of what kind of shunt
left to right shunt
describe atrial septal defect
communication of blood between atria.
why is atrial septal defect initially a L-R shunt.
It is classified a L-R shunt because initially the pulmonary resistance is less than the systemic resistance and because RV is capable of distension to accomodate increased volume. HT will eventually develop in pulmonary artery and increased resistance will shift it to a R-L shunt.
ventricular septal defect is an example of what kind of shunt
left to right shunt.
describe a ventricular septal defect
communication of blood between ventricles. this causes significant RV hypertrophy and hypertension in pulmonary artery from birth.
what kind of shunt is patent ductus arteriosus an example of
left to right shunt initially, however obstructive pulmonary vascular disease develops and eventually reverses it to a R-L shunt. (Eisenmengers syndrome/reaction)
describe patent ductus arteriosis
ductus arteriosus usually connects pulmonary artery and aorta during fetal development and prostaglandins usually shut this at birth. PDA is when the connection fails to close after birth.
What is Eisenmengers syndrome
the provess by which a L-R shunt causes increased flow through pulmonary vasculature resulting in pulmonary HT. This leads to elevated right sided pressure and reversal of shunt from L-R to R -L.
What are three examples of congenital obstructions
coarctation of aorta
pulmonary stenosis
aortic stenosis
describe coarctation of aorta
constriction of the aorta leading to HyperT in upper extremities but HypoT in lower extremities
describe difference between infantile coarctation and adult coarctation
infantile: proximal patent ductus arteriosis, symptoms occur early in life, lower body cyanosis.
adult: typical, ridge like infolding of the aorta opposite a closed ductus arteriosis. generally asymptomatic until later in life which manifest as enlarged intercostal arteries, saw tooth notching on ribs, stroke and brain aneuryism
define cardiomyopathy and the types
disease intrinsic to heart. types:
dilated (most common)
hypertrophic
restrictive
define dilated cardiomyopathy
progressive cardiac dilation and contraction (Systole) dysfunction. Causes - genetic, alcoholism, viral myocarditis, pregnancy
macroscopic features of dilated cardiomyopathy
heart is heavy, 2-3x the normal weight, large and flabby (dilation of all 4 chambers), thinned walls and hypocontraction
microscopic features of dilated cardiomyopathy
granular mural thrombosis, variable myocyte hypertrophy, abnormal filling (diastole). interstitial fibrosis,
define hypertrophic cardiomyopathy
genetic cause, characterised by hypertrophy and abnormal filling (Diastole) mostly due to mutations in genes of the sarcomere
most common genetic mutation underlying hypertrophic cardiomyopathy
Arg403-Gln403 in myosin heavy chain beta protein
macroscopic features of hypertrophic cardiomyopathy
heart is heavy, thick walled and hypercontracting. hypertrophy - chamber is compromised and cant hold sufficient blood for systemic circulation - compensates by contracting faster. Septal muscle bulges into the LV outflow tract, LA enlarged.
microscopic features of hypertrophic cardiomyopathy
disarray, extreme hypertrophy, characteristic branching of myocytes and interstitial fibrosis.
define rheumatic fever/ rheumatic heart disease
autoimmune mediated inflammatory disease occuring following group A streptococcal pharyngitis (strep throat).
what levels of the heart to RF/RHD effect
may effect heart at all three levels -
endocardium (valves)
myocardium (Aschoff bodies)
pericardium (fibrinous exudates)
what is a macroscopic characteristic of RF/RHD
non infectious vegetations (fibrin + platelets) along the mitral valve and thickening/shortening of the chordae tendinae. this results in eventual stenosis and regurgitation. ALSO Aschoff bodies and fibrinous pericarditis.
what are aschoff bodies composed of?
collagen surrounded by t lymphocytes and specialised macrophages (Anitschkow cells)
what is the interval between the throat infection and cardiac RHD
1-5 weeks, by this time the pharyngeal cultures for GAS are negative.
what is the pathogenesis of acute rheumatic fever
antibodies to GAS protein cross react with glycoprotein antigens in heart and joints. antibodies to streptococcal proteins e.g. m protein cross react with cardiac myosin
what are the clinical features of rheumatic fever?
- polyarthritis of large joints
- carditis
- subcutaneous nodules
- rash
- sydenhams chorea/ st vitus dance. uncontrolled movements.
what do aschoff nodules contain
swollen eosinophilic collagen surrounded by lymphocytes, occasionally plasma cells and plump macrophages.
what kind of inflammation is rheumatic myocarditis
granulomatous (foreign body type)
define infective endocarditis
when microorganisms from mouth (dental procedures) or from IV drug use lodge on a damaged valve, which causes large, infected vegetations to form on valve.
consequences of infective endocarditis
destruction of valve
embolism to brain, kidney, spleen,
what do the vegetations of infective endocarditis mostly consist of
thrombotic debris, immune cells and micro-organisms (usually bacterial)
what are the two types of infective endocarditis
acute - rapid destruction of valve, highly virulent organism, not good prognosis, often fatal despite intervention.
subacute - less virulent organism, colonisation of previously deformed valves, recovery likely.
what are the differences between vegetations of infective endocarditis and rheumatic heart disease
RHD vegetations are rows of small, warty vegetations along the lines of closure of the valve leaflets and are STERILE. ID vegetations are large, irregular masses on the valve cusps which can extend onto the chordae tendinae and are INFECTIVE.
Define congestive heart failure
the pathophysiological state in which an abnormality of cardiac function is responsible for the failure of the heart to pump blood at a rate commensurate with the requirements of metabolising tissues, despite adequate venous filling
AND OR
the heart can only pump adequately when there is an abnormally elevated diastolic volume.
what are the five clinical features of heart failure
- systolic vs diastolic
- high output vs low output
- acute vs chronic
- right sided vs left sided
- forward vs backward.
what is the difference between systolic and diastolic heart failure
systolic heart failure is an inability to contract normally
diastolic heart failure is inability to relax and or fill the heart normally