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02. Cardiovascular > L21. Ventricular Hypertrophy > Flashcards

L21. Ventricular Hypertrophy Flashcards

1
Q

What side of the heart does ventricular hypertrophy affect the most?

A

The left side

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2
Q

What is the difference between hyperplasia and hypertrophy?

A

Hyperplasia when cells proliferate and this processes ceases in the heart a few months after birth.
Hypertrophy is wen cells grow and this is normal parallel to growth. This stops after adolescence.

Hypertrophy can be restarted due to pressure demands throughout life.

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3
Q

How is normal hypertrophy controlled and influenced?

A

Endocrine control: Growth Hormones, IGF, and Thyroxine

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4
Q

What does the normal heart size depend on?

A

Body size, family history and genetics, athletic conditioning, blood pressure, angiotensin II and catecholamines

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5
Q

What is the mean left ventricular mass in young healthy adults?

A

160 g

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6
Q

How are the dimensions of the left ventricle normally measured?

A

Echocardiography or MRI

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7
Q

What is meant by cardiac remodelling and hypertrophy?

A

Any change in the size, shape and/or function of the heart following some form of cardiac injury

Hypertrophy = increase in LV mass

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8
Q

What kinds of cardiac injury lead to ventricular hypertrophy?

A 
Myocardial Infarction
Cardiac Inflammation (Eg. myocarditis)
Volume Overload (Regurgitation)
Pressure Overloads (stenosis)
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9
Q

What is cardiac remodelling?

A

Normal LV mass but there is an increase in the relative thickness of the walls (redistribution)

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10
Q

What is Concentric Hypertrophy?

A

An increase in BOTH mass and LV thickness of the wall
= More sarcomeres in parallel to one another
= Overall diameter of the heart doesn’t necessarily change
= reduced chamber volume
= due to PRESSURE OVERLOAD (eg. aortic stenosis, chronic hypertension)

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11
Q

What is Eccentric Hypertrophy?

A

An increase in BOTH mass and thickness RELATIVE TO EACH OTHER
= More sarcomeres in series (cardiomyocyte elongation)
= large dilated ventricle
= due to VOLUME OVERLOAD (eg. regurgitation)

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12
Q

What are the characteristic of hypertrophy (at the cellular level)?

A

Increase in cell size (not number)
More mitochondria, myofibrils, SR
Increased fibroendothelial cell numbers
Increased interstitial matrix

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13
Q

What happens when the compensation (hypertrophy) fails and thus decompensation occurs?

A

LV dilation
Major increases in the pressure and volume in the ventricle
Reduced Ejection Fraction
Reduced systolic function and Cardiac Output
Eventual cardiac failure

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14
Q

What is the ejection fraction?

A

The percentage of blood leaving your heart each time it contract

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15
Q

Is hypertrophy symptomatic?

A

Normally hypertrophy is compensation and is asymptomatic. However at a some tipping point ‘something’ happens to cause decompensation

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16
Q

Why does concentric hypertrophy occur as a result of pressure overload?

A

A thicker wall is thought to reduce the wall stress (tension) according to Laplace’s Law
An adaptation to maintain the systolic function, cardiac output and end diastolic pressure

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17
Q

Why does eccentric hypertrophy occur as a result of volume overload?

A

Dilation of the ventricle and thicker wall maintains the stroke volume and ejection fraction.

18
Q

Why are the explanations for why concentric and eccentric hypertrophy occur controversial?

A

Because some studies that analyse subjects that don’t undergo hypertrophy have observed that they survive better than those that do - the compensatory mechanism may actually be making it worse

19
Q

What are environmental/pathogenic causes of left ventricular hypertrophy?

A

Pressure Overload or Volume overload
Following Myocardial Infarct of Cardiac Injury
Obesity
Diabetes
Renal Failure
Infiltration (amyloidosis or sarcoidosis)

20
Q

What are genetic causes of left ventricular hypertrophy?

A

Hypertrophyic cardiomyopathy

Fabry’s Disease (absence of an enzyme)

21
Q

What are some clinical features of LVH?

A

Forceful apex beat

Abnormal or extra heart sounds: S3 and S4

22
Q

What would an ECG display for LVH?

A

Tall voltages (QRS) and T wave insertions

23
Q

What would a cardiac xray (CXR) show for LVH?

A

An eccentric would show a large heart while concentric a normal sized heart

24
Q

What are the mechanisms that lead to left ventricular hypertrophy?

A

Still a widely unknown cause:

Angiotensin, aldosterone, catacholamines, local factors, cellular and molecular mechanisms, stem cells(?)

25
Q

What are the consequences of LVH?

A

Increased risk of ischaemic heart disease, cardiac failure, atrial fibrillation and stroke

Diastolic dysfunction (inability to fill)

26
Q

How do we currently treat LVH?

A

Treat the underlying condition/s

27
Q

What type of hypertrophy leads to the most highest increased risk of death following cardiovascular disease?

A

Concentric > Eccentric > Remodelling

28
Q

Why does diastolic dysfunction occur in LVH?

A

The thick muscle loses its compliance and thus it is difficult to relax
This means there is a poor filling and a higher pressure is required for dilation and for filling

29
Q

What is a result of diastolic dysfunction?

A

Increased EDP to achieve adequate filling.
This means a back flow of pressure into the left atrium and into the pulmonary system.
= pulmonary hypertension and left heart failure

30
Q

Why are patients with diastolic dysfunction more susceptible to fluid loading?

A

Administering too much fluid leads to shortness of breath and pulmonary oedema
Administer too less fluid leads to lost CO, decreased BP and dizziness

31
Q

Why are these patients with diastolic dysfunction more prone to atrial fibrillation?

A

Because the atrial kick is very important and is stronger to achieve adequate diastolic filling.
This more forceful pressure kick is sensitive to fibrillation

32
Q

What is Left Ventricular Remodelling?

A

A post-MI remodelling

  • scar tissue that becomes thin and dilated out
  • myocyte hypertrophy and apoptosis occurs increasing the LV volume
  • interstitial fibrosis occurs
33
Q

What are the causes of left ventricular remodelling?

A

Renin-Angiotensin-Aldosterone system, the adrenergic nervous system, endothelin, cytokines, local factors

34
Q

How is left ventricular remodelling prevented?

A

Giving angiotensin blocking and beta adrenergic blocking upon MI

35
Q

What are the consequences of LV remodelling?

A

Increased risk of heart failure and mortailtiy

36
Q

What two types of cardiomyopathy affect the size and shape of the heart?

A

Hypertrophic cardiomyopathy

Dilated cardiomyopathy

37
Q

What are some of the consequences of hypertrophic cardiomyopathy?

A

Depends on the severity:

Outflow obstruction, ventricular arrhythmia, shortness of breath, heart failure, syncope, sudden cardiac death

38
Q

What is the mechanism of hypertrophic cardiomyopathy?

A

Unclear:

May have to do with calcium transport, ATP usage, signalling?

39
Q

What is dilated cardiomyopathy?

A

When the heart enlarges and becomes weaker as a result. Mostly idiopathic causes (may have some genetic cause)

40
Q

What is athletes heart?

A

Common among competitive athletes where wall thickness decreases with ECCENTRIC HYPERTROPHY
while cardiac FUNCTION IS NORMAL
it usually regresses with deconditioning

41
Q

What are the causes of right ventricular hypertrophy?

A

Congenital (rare)
Pulmonary Hypertension ie. cor pulmonale, lung disease, PE
Chronic Left ventricular hypertension leading to right
Right heart valve problems

02. Cardiovascular (43 decks)

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