Week 3 topic 4 Flashcards
(24 cards)
Define cardiac remodelling?
Cardiac remodelling is a change in the size, shape and function of the heart in response to cardiac injury or increased workload.
Occurs in physiological and pathological conditions.
What factors influence cardiac remodelling?
Factors influencing cardiac remodelling include:
* Haemodynamic load
* Oxidative stress
* Production of endothelin
* Cytokines
* Nitric oxide (NO)
What is physiological remodelling?
Physiological remodelling refers to changes in the heart due to normal physiological processes such as exercise.
How does strength training such as weight lifting affect cardiac remodelling?
Strength training leads to:
* Increase in systolic and diastolic pressure
* Pressure overload causes stretching of cardiomyocytes
* Promotes parallel addition of sarcomeres
* Lateral growth of cardiomyocytes
* Results in concentric hypertrophy or increase in ventricular wall thickness.
How does endurance training affect cardiac remodelling?
Endurance training results in:
* Increase in blood volume (Increased albumin, ADH and aldosterone)
* Volume overload of the ventricles
* Stretching of the cardiomyocytes
* Promotes addition of sarcomeres in-series
* Longitudinal growth of cardiomyocytes
* Results in eccentric hypertrophy or dilation of the ventricular chambers.
What is pathological remodelling?
Pathological remodelling occurs due to disease processes that lead to changes in heart structure and function.
What are the effects of myocardial infarction on cardiac remodelling?
Myocardial infarction leads to:
* Ischaemia
* Necrosis of cardiomyocytes
* Influx of inflammatory cells
* Fibrosis of infarct and surrounding myocardium
* Thinning of the ventricular wall and loss of function.
* Ventricular dysfunction and heart failure
What are the consequences of hypertension on cardiac remodelling?
Hypertension causes:
* Stretching of cardiomyocytes
* Addition of sarcomeres in parallel
* Concentric hypertrophy
*Increased ventricular wall thickness
* Increased stiffness of myocardium
* Diastolic dysfunction and heart failure.
What happens in the case of aortic and mitral regurgitation?
Aortic and mitral regurgitation lead to:
* Volume overload
*Addition of sarcomeres in series
* Eccentric hypertrophy of the left ventricle
* Dilation of the ventricular chamber
* Systolic dysfunction of LV causes stasis of blood and reduced cardiac output.
What is the relationship between myocyte hypertrophy and capillary numbers?
Myocyte hypertrophy is not accompanied by a proportional increase in capillary numbers.
What are the metabolic demands of a hypertrophied heart?
A hypertrophied heart has:
* Increased mass
* Increased heart rate
* Increased contractility
* Increased cardiac oxygen consumption.
What is concentric remodelling?
Concentric remodelling occurs in response to pressure overload, leading to:
* Addition of sarcomeres in parallel
* Left ventricular wall thickening without an increase in chamber size.
What are the complications of concentric remodelling?
Complications of concentric remodelling include:
* Increased stiffness
* Reduced ventricular compliance
* Impaired diastolic filling
* Heart failure.
What is eccentric remodelling?
Eccentric remodelling occurs in response to volume overload, characterized by:
* Addition of sarcomeres in series
* Left ventricular chamber dilation so the wall becomes thinner or remain the same
What are the complications of eccentric remodelling?
Complications of eccentric remodelling include:
* Reduced mechanical efficiency
* Impaired systolic and diastolic function
* Reduced contractility
* Reduced ejection fraction.
What diagnostic methods are used for cardiac remodelling?
Diagnostic methods include:
* Imaging studies
* ECHO
* Ventriculography
* CT
* CMR.
What changes are assessed in cardiac remodelling diagnosis?
Changes assessed include:
* Cavity diameter
* Mass (hypertrophy/atrophy)
* Geometry (heart wall thickness and shape)
* Fibrosis.
What are newer diagnostic methods for cardiac remodelling?
Newer diagnostic methods include detection of:
* Alpha-actin
* Myosin heavy chain
* Natriuretic peptide
* Angiotensin-converting enzyme
* Shift from fatty acid to glucose oxidation.
In what hypertrophy are sarcomeres added in parallel?
Concentric hypertrophy
In what hypertrophy are sarcomeres added in series
Eccentric hypertrophy
When does concentric hypertrophy occur?
Pressure overload
Strength training
Hypertension
When does eccentric hypertrophy occur?
Volume overload
Endurance training (aerobics)
aortic and mitral regurgitation
What is the following hypertrophy
Concentric hypertrophy
- parallel
What is the following hypertrophy
Eccentric hypertrophy
- in series
