Ventricular Hypertrophy Flashcards
(27 cards)
What hormones are important in embryonic myocardial hyperplasia (growth)?
GH, Insulin GF, Thyroxine
What are the determinants of normal heart size?
- Body size & surface area
- genetics
- athletic conditioning (~larger)
- BP
- Angiotensin II
- Catecholamines
What is hypertrophy?
Increase in LV mass relative to body size
What is relative wall thickness?
LV wall thickness/LV chamber size
What is remodeling?
increased relative wall thickness without increased LV mass
(looks thicker but the heart gets smaller)
Concentric Hypertrophy
- Increased LV mass & increased relative wall thickness
- Walls thickened, no enlargement
- tf decreased volume
- usually due to pressure overload (high afterload)
- more sarcomeres in parallel
- thickened wall to reduce wall stress
- to maintain systolic function e.g. CO, LVEDP
Eccentric Hypertrophy
- Increased LV mass, normal relative wall thickness
- overall enlargement - large dilated heart
- increased volume
- often due to volume overload (leaky mitral, aortic; ventricular, septal shunt; high preload)
- myocyte stretching - more sarcomeres in series
- maintain SV by +LVEDV, +EF (i.e. gets larger to pump a bigger SV each beat)
Dilated heart is analagous to
Eccentric hypertrophy
Thickened heart is analagous to
Concentric Hypertrophy
Laplace’s Law
Thicker wall reduces or normalizes wall stress - e.g. in concentric hypertrophy due to pressure overload
Decompensation
- long term, failure of compensation
- LV dilation to +SV
- +LVEDV
- +LVESV
- -EF
- -SV
- -CO
- eventual heart failure
What are the environmental causes of LVH?
Environmental:
- Concentric: P overload (high afterload) from HT, aortic stenosis
- Eccentric: V overload (high preload) from mitral or aortic regurge, ventricular septal defects
- Post-MI
- Post-cardiac injury e.g. myocarditis
- Obesity
- Diabetes
- Renal failure
- Infiltration by proteins e.g. amyloidosis (dep in ECM)
What are the genetic causes of LVH?
- Hypertrophic cardiomyopathy
- Fabry’s disease: x-linked enzyme deficiency
What are the clinical signs of LVH?
Forceful apex beat
S3 & S4 sounds present
What are the ECG indicators of LVH?
tall volatages
inverted T waves
What are the signs of LVH on chest x-ray (CXR)?
large heart if Eccentric LVH
normal size if Concentric LVH
What tests are ordered for diagnosis of LVH?
- ECG
- CXR
- Echo
- MRI
- CardioCT
LVH increases risk of:
- ischaemic heart disease
- cardiac failure
- atrial fibrillation
- stroke
- diastolic dysfunction (doesn’t fill well)
Left ventricular remodeling following MI involves
- Increased LV volume, more spherical shape
- myocyte hypertrophy and apoptosis
- interstitial fibrosis (scar tissue, collagen)
What are the consequences of LVH remodeling?
- Increased heart failure
- Mortality [-EF, +EDV, larger infarct segment length]
What are the causes of RVH?
Congenital
- transposition (switched anatomy) of great arteries i.e. RV pumps into systemic, LV pumps into pulmonary - RVH to cope
Pulmonary Hypertension (creates a high P pulm circuit)
- lung disease
- pulmonary embolus
- chronic left HF
Right heart valves (less common than left)
- Pulmonary stenosis or regurge
- Tricuspid regurge
Hypertrophic Cardiomyopathy
- Genetic condition, autosomal dominant
- Mutation in genes for sarcomere proteins
- Beta cardiac myosin heavy chain
- cardiac myosin binding protein
- cardiac troponin I & T
What are the characteristics of HCM (hypertrophic cardiomyopathy)?
- Asymmetrical hypertrophy of LV, especially septum
- Cellular hypertrophy
- myocyte disarray
What is the main issue of HCM?
- Muscle is prone to abnormal rhythms
- it is NOT that the cavity is reduced tf -filling
