Structural Heart Disease Flashcards
What are the determinants of cardiac stroke volume?
Starling’ law of the heart (length tension)
Cardiac contractility
Arterial pressure
What influences cardiac contractility?
Synthetic tone
Adrenaline
What is the after load?
Pressure in the aorta
Force per unit area
What is preload?
Stretching of the myocardium allowing the generation of forces
What is the law of laplace?
P + 2T/r
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 classification of valvular disease?
Stenotics
Dilatations
What are two types of stenotic lesions?
Aortic stenosis
Mitral stenosis
What is aortic stenosis?
Aortic valve becomes significantly narrowed
Severe is area is less than 1cm^2 or if speed of blod flow is greater that 4 metres per second
What are the causes of aortic stenosis?
Bicuspid aortic valve - Congenital
Degeneration of valve with age
Rheumatic heart disease
Infective endocarditis
What cause mitral stenosis?
Rheumatic fever Congential Rheumatoid arthritis Lupus Whipples disease
What is the consequence of aortic stenosis?
Increased afterload on the left ventricle
Causing hypertrophy
What is the consequence of mitral stenosis?
Increased pressure on the left atrium
Increased strain causes atrial dilation
Can lead to AF
What causes mitral regurgitation?
Rheumatic fever
Infective endocarditis
Mitral valve prolapse
What is the consequence of mitral regurgitation?
Less cardiac output to aorta
Reduces organ perfusion
What causes aortic regurgitation?
Biscuspid aortic valve
Marfaans syndrome
hypertension
Infective endocarditis
What is the consequence of aortic regurgitation?
Volume overload to left ventricle as blood goes back
Causing dilation
How does mitral regurgitation present?
systolic murmur
How does aortic regurgitation present?
diastolic murmur
What are the three main types of cardiomyopathy?
Hypertrophic
Dilated
Arrhythmogenic right ventricular
What is the result of dilated cardiomyopathy?
Chambers have poor contractility
Wall tension does not generate effective pressure
What can cause dilated cardiomyopathy?
Stress
Post partum
Sarcodosis
Auto-immune diseases
What happens in arrhthmogenic right ventricular cardiomyopathy?
Abnormal right ventricle radius
Cannot work effectively
Also effect left ventricle
How can you treat valve 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
- last longer
- need to be on warfarin
Prosthetic valves
-only last 20 years
Why is the mitral valve not often replaced?
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
Define cardiogenic shock?
Impairment of cardiac systolic function resulting in reduced cardiac output causing end organ dysfunction
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
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
How do you calculate cardiac output?
Stroke volume x Heart rate
How do you calculate ejection fraction?
Stroke volume divided by end diastolic volume
How do you calculate mean arterial pressure?
MAP = Cardiac output x total peripheral resistance
MAP = Diastolic blood pressure + 1/3 Pulse Pressure
MAP = 2/3 Diastolic blood pressure + 1/3 Systolic Pressure
What is infective endocarditis?
Infection of the endocardium (inner lining of the heart). Commonly caused by bacteria.
How do you diagnose infective endocarditis?
Dukes criteria
Major: positive blood cultures/evidence of endocardium involvement
Minor: predisposing factors, pyrexia, vascular phenomena, immunological phenomena, microbioloigcal evidence
Blood cultures
ECG
ECHO
Which part of the heart does infective endocarditis affect particularly?
Heart valves, normally left aortic and mitral valves
Right sided occurs less frequently
What are some features of decompensation?
Weight loss
Difficulty breathing
Leg/Foot Swelling
Fatigue
What is the relationship between IV drug use and infective endocarditis?
Higher risk of developing infective endocarditis
Can be right sided involving the tricuspid
Define dilated cardiomyopathy
Ventricle stretches and thins and is no longer able to pump efficiently
What are some common causes of dilated cardiomyopathy?
Heart disease Poorly controlled hypertension Infection Genetics Peri-partum Toxins Auto-immune Endocrine Metabolic disorders
What genes have been implicated in the diagnosis of dilated cardiomyopathy?
MYH7, MYBPC3, TNNT2, and TNNI3
ACBC1, ACBC 2
How is dilated cardiomyopathy managed?
Medication: Diuretics, ACEi, Beta Blockers, Anti-coagulants, ARBs
Pacemaker
Surgical: LVAD (Left ventricular assist device) or Heart transplant
What are the implications of dilated cardiomyopathy?
High risk of heart failure
Needs to manage BP
Lower alcohol intake, stop smoking, minimise salt and caffeine
