Structural Heart Disease

Question 1

What are the determinants of cardiac stroke volume?

Answer 1

Determined by the preload and afterload of the heart

Preload =
Starling’ law of the heart (length tension)
Cardiac contractility

Afterload =
Arterial pressure

Question 2

What influences cardiac contractility?

Answer 2

Synthetic tone
Sympathetic fibres / innervation
Adrenaline

Question 3

What are the definitions of preload and afterload?

Answer 3

Preload = Stretching of the myocardium allowing the generation of forces

Afterload = Pressure in the aorta
Force per unit area

Question 4

What is Laplace’s law?

Answer 4

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

Question 5

Why is the law of laplace significant?

Answer 5

When radius of chamber increases pathologically

cannot generate sufficient pressure

Question 6

What are the two classifications of valvular disease?

Answer 6

Stenotic lesions - narrowing of the valve

Regurgitations - dilatation of the valve

Question 7

What are the four stenotic lesions?

Which of these are more significant?

Answer 7

Pulmonary stenosis
Tricuspid stenosis
Aortic stenosis
Mitral stenosis

Aortic and mitral stenosis

Question 8

What is aortic stenosis?

Answer 8

Aortic valve becomes significantly narrowed

Severe = area is less than 1cm^2 or if speed of blood flow is greater that 4 m/s

Question 9

What are the causes of aortic stenosis?

Answer 9

Congenital - bicuspid aortic valve

Degeneration of valve with age

Rheumatic heart disease

Infective endocarditis

Question 10

What cause mitral stenosis?

Answer 10

Rheumatic fever
Congential
Rheumatic arthritis
Lupus
Whipples disease

Question 11

What is the consequence of atrial stenosis?

What is the consequence of mitral stenosis?

Answer 11

Increased afterload on the left ventricle
Causing hypertrophy

Increased pressure on the left atrium
Increased strain causes atrial dilation
Can lead to atrial fibrillation

Question 12

What causes mitral regurgitation and what does that lead to?

Answer 12

Rheumatic fever
Infective endocarditis
Mitral valve prolapse

Less cardiac output to aorta
Reduces organ perfusion

Question 13

What causes aortic regurgitation and what does this lead to?

Answer 13

Biscuspid aortic valve
Marfaans syndrome
hypertension
Infective endocarditis

Volume overload to left ventricle as blood goes back
Causing dilation

Question 14

How does mitral regurgitation present?

How does aortic regurgitation present?

Answer 14

Systolic murmur

Diastolic murmur

Question 15

What are the three main types of cardiomyopathy?

Answer 15

Hypertrophic - heterogenous condition, high risk of mortality

Dilated

Arrhythmogenic right ventricular

Question 16

What can cause dilated cardiomyopathy and what can it lead to?

Answer 16

Stress
Post partum
Sarcodosis
Auto-immune diseases

Chambers have poor contractility
Wall tension does not generate effective pressure

Question 17

What happens in arrhythmogenic right ventricular cardiomyopathy?

Answer 17

Abnormal right ventricle radius
Cannot pump effectively
Also effects left ventricle

Question 18

How can you treat valvular issues?

Answer 18

Valve replacement

But must treat consequences of valve failure

Aim to replace before the issues has other effects

Question 19

What are the pros and cons of different valves?

Answer 19

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

Question 20

Why is the mitral valve not often replaced?

How can mitral valve issues be treated instead?

Answer 20

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

Question 21

What is cardiogenic shock?

Answer 21

Impairment of cardiac systolic function resulting in reduced cardiac output causing end organ dysfunction

81% of cases due to MI

Question 22

Why is it so important to identify cardiogenic shocl?

Answer 22

Treatment is very different to other types of shock
e.g. dangerous to give more fluid
reduces contractile function

Question 23

How is cardiogenic shock treated?

Answer 23

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

Question 24

What are inotropes?

Answer 24

Dopamine etc.
Increase height and leftward shift of pressure volume loop

Augmentation of end diastollic volume

Increase in stroke work and stroke volume

Question 25

What are the features of mechanical support devices?

Answer 25

Used when ionotropic drugs are ineffective

IABP
Impella recover
TandemHeart
VA-ECMO