Determinants and Consequences of Ventricular Hypertrophy Flashcards
What is involved in normal heart growth?
Cell proliferation as an embryo and cell hypertrophy during childhood
What does normal heart size depend on?
Body size, genetics, athletic conditioning, blood pressure, angiotensin II and catecholamines
When does remodelling and hypertrophy occur?
In response to myocardial infarction, myocarditis, volume overload, pressure overload
What is hypertrophy?
Increase in LV mass relative to body size
What is relative wall thickness?
Wall thickness over chamber size
What is remodelling?
Increased relative wall thickness without an increase in mass
What is concentric hypertrophy?
Increase in mass and increase in relative wall thickness - chamber size stays the same. Due to more sarcomeres in parallel.
What is eccentric hypertrophy?
Increase in mass but normal relative wall thickness - chamber size increases. Due to more sarcomeres in series.
When does concentric hypertrophy occur?
Usually due to pressure overload
When does eccentric hypertrophy occur?
Usually due to volume overload
What happens in hypertrophy?
Increased myocardial cell size, increased fibroendothelial cell number, increased interstitial matrix
Why does concentric hypertrophy occur?
To compensate for pressure load- thicker wall reduces stress - able to maintain CO and and EDV
Why does eccentric hypertrophy occur?
To maintain SV by having a larger EDV
What happens in decompensation?
Reduced systolic function and cardiac output - leads to cardiac failure
What are the causes of LVH?
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)
What are the features of LVH on examination?
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
What are the mechanisms of LVH?
Not very well understood- involves angiotensin, aldosterone, catecholamines, local factors, cellular and molecular mechanisms
What are the consequences of LVH?
Increased risk of ischaemic heart disease, cardiac failure, atrial fibrillation, stroke - also causes diastolic dysfunction
What happens in diastolic dysfunction?
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
What is the treatment for LVH?
Have to target underlying conniption - repair or replace valve, treat hypertension, weight loss
When does left ventricular remodelling occur?
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
When does right ventricular hypertrophy occur?
Congenitally (transposition of great arteries), pulmonary hypertension (lung disease, pulmonary embolism, left heart failure), right heart valve problems (pulmonary stenosis/regurgitation or tricuspid regurgitation)
What is hypertrophic cardiomyopathy?
An autosomal dominant genetic condition that causes left ventricular hypertrophy due to myocyte disarray - may be mild or severe, can cause ventricular arrhythmias
What is athlete’s heart?
eccentric hypertrophy - may cause ventricular arrhythmia and sudden death
