Structural Heart Disease Flashcards
What are the determinants of cardiac stroke volume?
Determined by the preload and afterload of the heart
Preload =
Starling’ law of the heart (length tension)
Cardiac contractility
Afterload =
Arterial pressure
What influences cardiac contractility?
Synthetic tone
Sympathetic fibres / innervation
Adrenaline
What are the definitions of preload and afterload?
Preload = Stretching of the myocardium allowing the generation of forces
Afterload = Pressure in the aorta
Force per unit area
What is Laplace’s law?
P + 2T/r
P = pressure, T = tension, r = radius
Internal pressures generated inside a chamber is directly proportional to the tensions and inversely proportional to the radius
Why is the law of laplace significant?
When radius of chamber increases pathologically
cannot generate sufficient pressure
What are the two classifications of valvular disease?
Stenotic lesions - narrowing of the valve
Regurgitations - dilatation of the valve
What are the four stenotic lesions?
Which of these are more significant?
Pulmonary stenosis
Tricuspid stenosis
Aortic stenosis
Mitral stenosis
Aortic and mitral stenosis
What is aortic stenosis?
Aortic valve becomes significantly narrowed
Severe = area is less than 1cm^2 or if speed of blood flow is greater that 4 m/s
What are the causes of aortic stenosis?
Congenital - bicuspid aortic valve
Degeneration of valve with age
Rheumatic heart disease
Infective endocarditis
What cause mitral stenosis?
Rheumatic fever Congential Rheumatic arthritis Lupus Whipples disease
What is the consequence of atrial stenosis?
What is the consequence of mitral stenosis?
Increased afterload on the left ventricle
Causing hypertrophy
Increased pressure on the left atrium
Increased strain causes atrial dilation
Can lead to atrial fibrillation
What causes mitral regurgitation and what does that lead to?
Rheumatic fever
Infective endocarditis
Mitral valve prolapse
Less cardiac output to aorta
Reduces organ perfusion
What causes aortic regurgitation and what does this lead to?
Biscuspid aortic valve
Marfaans syndrome
hypertension
Infective endocarditis
Volume overload to left ventricle as blood goes back
Causing dilation
How does mitral regurgitation present?
How does aortic regurgitation present?
Systolic murmur
Diastolic murmur
What are the three main types of cardiomyopathy?
Hypertrophic - heterogenous condition, high risk of mortality
Dilated
Arrhythmogenic right ventricular
What can cause dilated cardiomyopathy and what can it lead to?
Stress
Post partum
Sarcodosis
Auto-immune diseases
Chambers have poor contractility
Wall tension does not generate effective pressure
What happens in arrhythmogenic right ventricular cardiomyopathy?
Abnormal right ventricle radius
Cannot pump effectively
Also effects left ventricle
How can you treat valvular issues?
Valve replacement
But must treat consequences of valve failure
Aim to replace before the issues has other effects
What are the pros and cons of different valves?
Metallic valves =
Used more so in the past
Lasts longer - used in the younger population
Need to be on warfarin
Prosthetic biological valves =
Only last 20 years
Why is the mitral valve not often replaced?
How can mitral valve issues be treated instead?
The arrangement of the mitral valve means that it isn’t easy to replace
Increased emphasis on repairing the existing valves
This avoids open heart surgery
Increasing use of the mitraclip - catheter used to implant small clip onto mitral valve to help it close more completely
What is cardiogenic shock?
Impairment of cardiac systolic function resulting in reduced cardiac output causing end organ dysfunction
81% of cases due to MI
Why is it so important to identify cardiogenic shocl?
Treatment is very different to other types of shock
e.g. dangerous to give more fluid
reduces contractile function
How is cardiogenic shock treated?
Early coronary angiography
PCI or CABG
Reassess haemodynamic/tissue perfusion
First line of treatment = inotropes (medicines that change the force of your heart’s contraction)
Second line of treatment = Advanced mechanical support
What are inotropes?
Dopamine etc.
Increase height and leftward shift of pressure volume loop
Augmentation of end diastollic volume
Increase in stroke work and stroke volume
What are the features of mechanical support devices?
Used when ionotropic drugs are ineffective
IABP
Impella recover
TandemHeart
VA-ECMO
