(cardioresp) structural heart disease Flashcards
what is the tricuspid valve?
the valve that allows blood to flow from the right atrium to the right ventricle
prevents blood from flowing backward
where is the tricuspid valve found?
attached to the walls of the right ventricles via the chordae tendinae (three cusps)
what is the mitral valve?
the valve that allows blood to flow from the left atrium to the left ventricle
prevents blood from flowing backward
where is the mitral valve found?
attached to the walls of the left ventricles via the chordae tendinae (two cusps)
how many cusps does the tricuspid valve have?
three
how many cusps does the mitral valve have?
two
what are the semi-lunar valves?
pulmonary valve (right ventricle)
atrial valve (left ventricle)
when does blood move past the semi-lunar valves?
when the ventricles contract, blood is pushed past the semi-lunar valves to either the lungs for oxygenation OR to the rest of the body
what is the heart made up of?
myocardium
what are the layers of the heart?
epicardium (epithelial cells)
myocardium
endocardium
define systole
contraction
define diastole
relaxation
what are the two main categories of structural heart disease?
congenital (from birth)
acquired (happen later in life)
what are examples of congenital structural heart diseases?
atrial septal defect (ASD)
ventricular septal defect (VSD)
coarctation of aorta (part of the aorta being narrower)
patent foramen ovale (PFO - opening bw two atria in atrial septum)
patent ductus arteriosus (extra blood vessel between aorta and pulmonary artery)
tetralogy of fallot (TFO)
what are examples of acquired structural heart diseases?
valvular dysfunctions (atrial/mitral stenosis or regurgitation)
cardiomyopathies
what is ventricular septal defect?
wall between two ventricles fails to develop properly so mixing of oxygenated and deoxygenated blood
how does ventricular septal defect present?
poor weight gain, palpitations, poor feeding
how is ventricular septal defect treated?
either if hole is small enough = closes on its own
OR
cardiac catherisation/open heart surgery
what are the congenital defects in TFO?
tetralogy of Fallot
1) ventral septal defect (VSD)
2) pulmonary valve stenosis
3) misplaced aorta
4) right ventricular hypertrophy
what is atrial septal defect?
hole in the septum between the atria
can occur during embryonic development if the two atria fail to develop properly
what is coarctation of the aorta?
narrowing of wall of aorta SO blood has to force through a narrower exit
= so ventricle has to work harder to push blood out to the rest of the body (can lead to LVH)
which heart valves are most commonly affected by stenosis or regurgitation?
aortic valve (1)
mitral valve
define stenosis
narrowing
define regurgitation
incompetence leading to backflow
what is the most common valvular disease requiring treatment?
aortic stenosis
second most frequent cause of cardiac surgery
what precedes aortic stenosis?
aortic sclerosis = aortic valve thickening without flow limitation
what is aortic stenosis?
narrowing of the aortic valve
how is aortic stenosis suspected?
auscultating heart of patient = early-peaking, shrill, systolic ejection murmur
confirmed by echocardiography
why does aortic stenosis cause an early-peaking systolic ejection murmur?
due to aortic sclerosis (thickening of the aortic valve)
what are the causes of aortic stenosis?
rheumatic heart disease
congenital heart disease
calcium build-up (age-related)
what are the risk factors for aortic stenosis?
hypertension
high LDL levels
smoking
elevated CRP
congenital bicuspid valves (aortic valves have two instead of three cusps)
CKD
radiotherapy
old age
what is bicuspid aortic valve disease and why is it a risk factor for aortic stenosis?
instead of having three cusps, the aortic valve has two cusps
1 = automatic narrowing (stenosis) of the aortic valve 2 = more prone to wear and tear and infection (can lead to stenosis)
(can also cause aortic regurgitation)
describe the pathophysiology of aortic stenosis
abnormal blood flow across the valve (e.g. due to bicuspid aortic valve) OR an unknown trigger
= vascular endothelium is damaged
= endocardial injury
= inflammatory process initiated (similar to atherosclerosis)
= leaflet fibrosis + deposition of calcium on the valve
= progressive fibrosis and calcium deposition limit aortic leaflet mobility
= aortic stenosis
describe the pathophysiology of aortic stenosis caused by rheumatic disease
Streptococcus infection targets the valvular endothelium
= autoimmune inflammatory reaction
= calcification
= limits aortic leaflet mobility
= aortic stenosis
what is rheumatic heart disease?
rheumatic heart disease starts as a sore throat from a bacterium called Streptococcus pyogenes
sometimes = repeated strep infections
= cause the immune system to react against the tissues of the body i.e. inflaming and scarring the heart valves
= rheumatic fever
(so rheumatic heart disease results then from the inflammation and scarring of heart valves caused by rheumatic fever)
what is rheumatic fever?
when there are repeated strep infections cauing the body to produce an immune response against the body’s own tissues
= inflammation + scarring of the heart valves
what are the complications of untreated or poorly managed aortic stenosis?
left ventricular hypertrophy
systolic heart failure
how does aortic stenosis lead to left ventricular hypertrophy?
aortic stenosis blocks left ventricular outflow
the left ventricle needs to generate excess pressure to pump out sufficient amounts of blood
afterload increases
heart responds by increasing muscle muscle to allow the increased pressure requirements to be met
= LVH
how does left ventricular hypertrophy lead to systolic heart failure?
long-standing, increased afterload = LVH
if aortic stenosis continues to worsen after this
= still increased afterload
= adaptive mechanism of LVH fails
= left ventricular wall stress increases
LVW stress increase causes systolic function to decline
= systolic heart failure
