Structural Heart Disease Flashcards
What are the determinants of stroke volume?
arterial pressure (preload/afterload) energy of contraction: (starling's law, contractility)
What is Starling’s Law?
the more the heart fills the harder it will contract therefore the bigger the stroke volume (up to a point)
What is the Anrep effect?
autoregulation method in which myocardial contractility increases with afterload
What is the law of Laplace?
the tension within the wall of a sphere filled to a particular pressure depends on the thickness of the sphere (inversely proportional)
Give an equation for the law of Laplace.
pressure = (2 x thickness x stress)/radius = 2x tension/radius
Label a normal pressure volume loop.
valves opening and closing isometric relaxation/contraction diastolic filling ventricular ejection SBP/DBP ESV/EDV SV
What is aortic stenosis?
narrowing of the aortic valve opening
What is mitral stenosis?
narrowing of the mitral valve opening
Classify types of valvular dysfunction.
narrowing ie stenotic lesions
dilatation ie regurgitation
Valvular dysfunction is more clinically significant on what side of the heart?
left
When is aortic stenosis classified as severe?
when aortic valve area is <1cm2
speed of blood flow >4m/s
What investigation can be done to assess severity of aortic stenosis?
trans thoracic echocardiogram
Common causes of aortic stenosis
bicuspid aortic valve
degeneration of valve in elderly
rheumatic heart disease
Rare causes of aortic stenosis
infective endocarditis
hyper urethemia
Causes of mitral stenosis
rheumatic fever
congenital mitral stenosis
features of lupus, rheumatoid arthritis
How does aortic stenosis affect the heart?
increased afterload > contraction of LV is less effective > LV abnormally remodels > LV hypertrophy
How does mitral stenosis affect the heart?
increased pressure on LA > more strain on LA > LA dilates
Aortic stenosis can be discovered by what heart sound heard when?
murmur
systole
Dilation of mitral and aortic valves causes?
mitral regurgitation
aortic regurgitation
Cause of mitral regurgitation?
rheumatic fever mitral valve prolapse coronary artery disease or heart attack rheumatoid arthritis endocarditis ventricular dilation
What effect does regurgitation have on cardiac output?
decreases
Cause of aortic regurgitation?
Congenital heart valve disease Age-related changes to the heart Endocarditis Rheumatic fever Other diseases Trauma
Classify cardiomyopathies.
hypertrophic
dilated
arrhythmogenic right ventricular
List treatment modalities.
valve replacement (surgery/intervention via catheter)
What are types of valve replacement?
aortic+mitral
aortic only
What are advantages and disadvantages to metallic valve replacement?
adv - last up to 20 years, can avoid multiple surgeries/scarring
disadv - have to take warfarin (complicated monitoring/interactions with other meds)
Define cardiogenic shock.
impairment of cardiac systolic function resulting in reduced cardiac output causing end organ dysfunction
How do you treat cardiogenic shock?
early coronary angiography > PCI > reassess haemodynamics/tissue perfusion : if improved, review and wean as indicated. if persistent, reimage for RV involvement/mechanical complications > advanced support
the majority of cardiogenic shock cases are caused by?
myocardial infarction
define inotrope
an agent that influences the force of muscular contraction
list inotropes used in cardiogenic shock
cAMP
phosphodiesterase inhibitor
what types of drugs are used to treat cardiogenic shock?
inotropes
vasopressors
list vasopressors used in cardiogenic shock
dopamine
epinephrine
norepinephrine
