Determinants and Consequences of Ventricular Hypertrophy

Question 1

What is involved in normal heart growth?

Answer 1

Cell proliferation as an embryo and cell hypertrophy during childhood

Question 2

What does normal heart size depend on?

Answer 2

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

Question 3

When does remodelling and hypertrophy occur?

Answer 3

In response to myocardial infarction, myocarditis, volume overload, pressure overload

Question 4

What is hypertrophy?

Answer 4

Increase in LV mass relative to body size

Question 5

What is relative wall thickness?

Answer 5

Wall thickness over chamber size

Question 6

What is remodelling?

Answer 6

Increased relative wall thickness without an increase in mass

Question 7

What is concentric hypertrophy?

Answer 7

Increase in mass and increase in relative wall thickness - chamber size stays the same. Due to more sarcomeres in parallel.

Question 8

What is eccentric hypertrophy?

Answer 8

Increase in mass but normal relative wall thickness - chamber size increases. Due to more sarcomeres in series.

Question 9

When does concentric hypertrophy occur?

Answer 9

Usually due to pressure overload

Question 10

When does eccentric hypertrophy occur?

Answer 10

Usually due to volume overload

Question 11

What happens in hypertrophy?

Answer 11

Increased myocardial cell size, increased fibroendothelial cell number, increased interstitial matrix

Question 12

Why does concentric hypertrophy occur?

Answer 12

To compensate for pressure load- thicker wall reduces stress - able to maintain CO and and EDV

Question 13

Why does eccentric hypertrophy occur?

Answer 13

To maintain SV by having a larger EDV

Question 14

What happens in decompensation?

Answer 14

Reduced systolic function and cardiac output - leads to cardiac failure

Question 15

What are the causes of LVH?

Answer 15

pressure overload (aortic stenosis, hypertension), volume overload (valve regurgitation, septal defect), myocardial infarction, myocarditis, obesity, diabetes, renal failure, infiltration, hypertrophic cardiomyopathy (genetic), fabry’s disease (genetic)

Question 16

What are the features of LVH on examination?

Answer 16

forceful apex beat, 3rd and 4th heart sound, tall voltages on ECG, inversion of T wave, large heart size on X-ray (if eccentric) - more accurate diagnosis using echo, MRI and CT

Question 17

What are the mechanisms of LVH?

Answer 17

Not very well understood- involves angiotensin, aldosterone, catecholamines, local factors, cellular and molecular mechanisms

Question 18

What are the consequences of LVH?

Answer 18

Increased risk of ischaemic heart disease, cardiac failure, atrial fibrillation, stroke - also causes diastolic dysfunction

Question 19

What happens in diastolic dysfunction?

Answer 19

The thickened muscle is stiffer, so a higher LVEDP is required to achieve the same LVEDV - the pressure backs up in to the LA and the pulmonary veins and causes pulmonary congestion

Question 20

What is the treatment for LVH?

Answer 20

Have to target underlying conniption - repair or replace valve, treat hypertension, weight loss

Question 21

When does left ventricular remodelling occur?

Answer 21

Following a myocardial infarction - the damage to the heart muscle and the following scar leads to dilation of the heart - can prevent this occurring with ACE inhibitors

Question 22

When does right ventricular hypertrophy occur?

Answer 22

Congenitally (transposition of great arteries), pulmonary hypertension (lung disease, pulmonary embolism, left heart failure), right heart valve problems (pulmonary stenosis/regurgitation or tricuspid regurgitation)

Question 23

What is hypertrophic cardiomyopathy?

Answer 23

An autosomal dominant genetic condition that causes left ventricular hypertrophy due to myocyte disarray - may be mild or severe, can cause ventricular arrhythmias

Question 24

What is athlete’s heart?

Answer 24

eccentric hypertrophy - may cause ventricular arrhythmia and sudden death