43 - Consequences, Determinants of Ventricular Hypertrophy

Question 1

Normal growth of the heart
1)
2)
3)

Answer 1

1) Cell hyperplasia in embryo. Ceases after a few months of life
2) Cell hypertrophy in childhood. Parallels body growth.
3) Doubles in size in six months. Triples in size by 1 year.

Question 2

How is cardiac hypertrophy during childhood mediated?

Answer 2

Thyroxine, Growth hormone, IGF control

Question 3

Factors that normal heart size depends on 
1)
2)
3)
4)
5)

Answer 3

1) Body size (lean body mass)
2) Family history
3) Athletic conditioning
4) Blood pressure
5) Angiotensin II, catecholamines

Question 4

Mean adult left ventricular mass

Answer 4

159g

Question 5

How are LV dimensions measured?

Answer 5

Echocardiogram or MRI

Question 6

Definition of cardiac hypertrophy

Answer 6

Increase in LV mass relative to body size

Question 7

Relative LV wall thickness

Answer 7

LV wall thickness/LV chamber size

Question 8

Causes of cardiac remodelling and hypertrophy
1)
2)
3)
4)

Answer 8

1) Myocardial infarction
2) Cardiac damage, EG: myocarditis
3) Volume overload
4) Pressure overload

Question 9

Hypertrophy patterns
1)
2)
3)

Answer 9

1) Concentric hypertrophy
2) Eccentric hypertrophy
3) Remodelling

Question 10

Morphology of LV concentric hypertrophy

Answer 10

Increased LV mass with increased relative wall thickness.
LV mass increases, but LV enlargement doesn’t occur.
IE: lumen narrows, wall thickens into lumen.
More sarcomeres in parallel

Question 11

Morphology of LV eccentric hypertrophy

Answer 11

Increase in LV mass, relative wall thickness stays the same (heart increases in size).
IE: lumen doesn’t narrow
More sarcomeres in series

Question 12

Difference in aetiology of concentric and eccentric hypertrophy

Answer 12

Concentric - often due to pressure overload

Eccentric - Often due to volume overload

Question 13

Dallas heart study classifications of cardiac hypertrophy 
1)
2)
3)
4)

Answer 13

1) Thick
2) Dilated
3) Thick and dilated
4) Indeterminate

Question 14

Concentricity

Answer 14

Increased wall thickness

Question 15

Cellular makeup of hypertrophic cardiac tissue
1
2
3

Answer 15

1) Increased myocyte size
2) Increased fibroendothelial cell numbers
3) Increased interstitial matrix

Question 16

Why might the body thicken LV wall in response to high pressure?

Answer 16

Thicker wall reduces or normalises stress (Laplace’s law)
Maintains systolic function, CO, LVEDP
This might not actually be a beneficial adaptation, though

Question 17

Why might the body dilate LV wall in response to high volume?

Answer 17

To compensate for volume load by increasing area of LV.

Maintain stroke volume by increasing LVEDV and ejection fraction

Question 18

Ejection fraction

Answer 18

Percentage of blood in ventricle ejected with each beat

Question 19

How can dilation lead to eventual cardiac decompensation?
1)
2)
3)

Answer 19

1) Dilation leads to increased LVEDV and LVESV, and reduced ejection fraction.
2) Increased end diastolic pressure reduces systolic function and CO
3) Eventual cardiac failure

Question 20

How does a heart appear when it decompensates?

Answer 20

Very dilated

Question 21

Cause of concentric hypertrophy

Answer 21

Excessive pressure, afterload (EG: hypertension, aortic stenosis)

Question 22

Causes of eccentric hypertrophy

Answer 22

Excessive volume, preload (EG: mitral, aortic regurgitation, ventricular septal defect)

Question 23

How can left ventricular hypertrophy be identified?
1)
2)
3)
4)
5)
6)

Answer 23

1) Forceful apex beat
2) Extra heart sounds (S3, S4)
3) Tall voltages, T-wave inversion on ECG
4) Echocardiogram
5) MRI
6) Cardiac CT

Question 24

Hypertrophic cardiomyopathy

Answer 24

Enlarged LV wall, particularly septum.
Cellular hypertrophy.
Cellular disarray

Question 25

Functional consequences of LVH

Answer 25

Diastolic dysfunction

Question 26

LVH gives increased risk of:
1)
2)
3)
4)

Answer 26

1) Ischaemic heart disease
2) Cardiac failure
3) Atrial fibrillation
4) Stroke

Question 27

Effects of LV hypertrophy on heartbeat 
1
2
3
4
5

Answer 27

1) Thickened muscle is stiff
2) Increased LVEDP required for the same LVEDV.
3) This increases left atrial pressure, therefore increases pulmonary vein pressure
4) This increases likelihood of pulmonary congestion
5) More sensitive to fluid loading (heart failure) or dehydration (low bp)

Question 28

When is atrial ‘kick’ more important?

Answer 28

Diastolic dysfunction from LV hypertrophy.
LV end diastolic pressure too high, so can’t fill ventricle from atrium passively.
Need atrial contraction to fill ventricle. In a healthy person, this atrial kick isn’t as important

Question 29

Symptoms of left ventricular diastolic dysfunction
1)
2)

Answer 29

1) If drink too much fluid, become short of breath (pulmonary oedema)
2) If drink too little, become dizzy (low bp)

Question 30

What is left ventricular remodelling?
1)
2)
3)
4)

Answer 30

1) Follows a myocardial infarct.
2) Infarct zone can become thin and elongated (fibrous scar)
3) Spherical ventricular dilation can occur through whole ventricle (not just at infarct zone)
4) Interstitial fibrosis occurs

Question 31

Causes of LV remodelling 
1)
2)
3)
4)

Answer 31

1) Renin-angiotensin-aldosteorne system
2) Sympathetic nervous system
3) Endothelin
4) Cytokines

Question 32

How can LV remodelling be reduced or blocked?

Answer 32

Block angiotensin or beta-adrenoceptors

Question 33

Predictions of mortality from LV hypertrophy types
1)
2)
3)
4)

Answer 33

In order of increasing likelihood of mortality:

1) Normal
2) Concentric remodelling
3) Eccentric hypertrophy
4) Concentric hypertrophy

Question 34

Causes of RV hypertrophy
1)
2)
3)

Answer 34

1) Congenital
2) Pulmonary hypertension
3) Right heart valve issues

Question 35

Congenital problem that could lead to RV hypertrophy

Answer 35

Transposition of the great arteries.

Aorta connected to RV, pulmonary artery connected to LV.

Question 36

Right heart valve problems that could lead to RV hypertrophy
1
2
3

Answer 36

1) Pulmonary valve stenosis
2) Pulmonary valve regurgitation
3) Tricuspid regurgitation

Question 37

How does hypertrophic cardiomyopathy develop?

Answer 37

Autosomal dominant.
Mutations in genes for sarcomere proteins.
Over 900 mutations in 12 genes found.
Heterogenous phenotype

Question 38

Most common mutant genes implicated in hypertrophic cardiomyopathy

Answer 38

Beta cardiac myosin heavy chain

Cardiac myosin binding protein

Question 39

Effects of hypertrophic cardiomyopathy
1
2
3

Answer 39

1) LV outflow tract obstruction
2) Diastolic dysfunction
3) Ventricular arrhythmias (can result in sudden death)

Question 40

Phenotypes of hypertrophic cardiomytopathy
1
2
3
4
5
6
7

Answer 40

1) Can be mild, asymptomatic
2) Outflow obstructions
3) Ventricular arrhythmias
4) Shortness of breath
5) Heart failure
6) Syncope
7) Sudden cardiac death

Question 41

Causes of dilated cardiomyopathy

Answer 41

Multiple causes, mostly idiopathic

Question 42

Athlete's heart
1)
2)
3)
4)
5)

Answer 42

1) Especially endurance athletes
2) Wall thickness over 14mm (normal is about 10mm)
3) Eccentric hypertrophy
4) Cardiac function normal
5) Usually regresses with deconditioning