Cardiac Hypertrophy Flashcards
What is cardiac hypertrophy ?
Adaptation of the heart which causes it to enlarge. This includes thickening of the wall, enlargement of cavities and an increased LV (left ventricle) mass.
What is the renin-angiotensin system (RAS) ?
The RAS is a hormonal system that helps regulating blood pressure and fluid balance.
What does RAS do during exercise ?
During exercise, the RAS constricts certain blood vessels and increases blood pressure to maintain blood flow to the muscles. This ensures the muscles obtain sufficient nutrients and oxygen.
What are the types of cardiac hypertrophy ?
“Physiological” hypertrophy from regular exercise or pregnancy - not associated with cardiac damage.
“Pathological hypertrophy” from unphysiological pressure or after myocardial infarction.
What are the causes of hypertrophy ?
- Intense sport activities
- Ventricular pressure overload (concentric hypertrophy) caused by hypertension
- Ventricular volume overload (eccentric hypertrophy) caused by valve insufficiency
- Genetic origin : hypertrophic cardiomyopathy
What is RWT (relative wall thickness) ?
RWT is defined as 2 times wall thickness divided by the left ventricular diastolic diameter
What happens to myocardiocytes during hypetrophic remodelling ?
Myocardiocytes increase in length and width. The heart undergoes a balanced hypertrophy (chambers, walls and septum all enlarge in unison).
What is a concentric adaptation of the heart ?
It’s a response to pressure overload and causes individual cardiomyocytes to increase in length and width
What happens to myocardiocytes in pathologic concentric hypertrophy ?
They increase in width compared to length, resulting in the wall and septal thickening and a loss of chamber area.
What is an eccentric adaptation of the heart ?
It’s a response to volume overload and causes individual cardiomyocytes to reduce in width and increase in length.
What happens to myocardiocytes in pathologic eccentric hypertrophy ?
They reduce in width and increase in length, causing extreme chamber enlargement with loss of wall
and septal thickness and large increases in wall tension.
What are the 3 main approaches to disitinguish a pathological and a phyisiological hypertrophy ?
- Electrocardiogram
- Echocardiography : cardiac chamber and wall dimension, valves insufficiency, heart function
- MRI : heart structure, function, fibrosis
What is bradycardia ?
Bradycardia is a slower than normal heart rate (lower than 60bpm). It’s often associated with an athlete’s heart.
What is cardiac fibrosis ?
It is a characteristic feature of pathological hypertrophy and heart failure. It’s characterized by increased collagen and ECM components in the heart muscle.
What happends to cardiomyocytes after birth ?
They stop cycling and switch from hyperplasia (growth by increasing number of cells) to hypertrophy (growth by increasing size of existing cells).
