Diseases of cardiovascular system atherosclerosis

 

 Diseases of cardiovascular system atherosclerosis;

  Overview;

• The term atherosclerosis (AS)  comes from the Greek athero, meaning gruel, and sclerosis meaning hardening.

• The time atherosclerosis and arteriosclerosis process are often used interchangeably.

• Arteriosclerosis process is a general term defined as a thickening of the walls of the vessels and a loss of vascular elasticity.

• Atherosclerosis process is the development of atherosclerotic plaque in the vascular wall that will occlude the lumen of The vessel and create ischemic conditions.

• The plaque begins as a fatty and fibrous growth, and overtime me calcify.

• The development of an atherosclerotic plaque can result in a restriction of blood flow severe enough to cause an infarct resulting in myocardial infarction or in a cerebrovascular accident (stroke).

• Therefore atherosclerosis is the root cause of two of the three leading cause of death in United, States coronary artery disease and stroke.

• In addition an atherosclerotic plaque in the leg can result in peripheral vascular disease that may result in the tissue that associated with gangrene and loss of a limb. Severe CVD may impair cardiac function to the point that congestive heart failure results.

     Stages of plaque progression:

• Monocytes- phagocyte white blood cell- circulate in the bloodstream and respond to injury on the artery wall.

• Monocytes slip under blood vessel cells and in gulf LDL cholesterol becoming foam cells. the thin layer of foam cells that develop on artery walls are known as fatty streaks.

• A fatty streak thickens and forms plaque as it accumulates additional lipids, smooth muscle cells, connective tissue and cellular debris.

• The artery may expand to accommodate plaque. when this occurs, the plaque that develop often contains a large lipid core with a thin fibrous covering and is vulnerable to rupture and thrombosis.

    Epidemiology:

• CVD is the leading cause of death throughout the world, and greater than 50% of all diagnosis related to CVD results from atherosclerosis.

    Etiology:

• The identified risk factors for CVD, PVD, and stroke include: 
• Family history
• Age 
• Sex 
• Obesity 
• Dyslipidemia 
• Hypertension 
• Diabetes 
• Physical inactivity 
• Cigarette smoking

• The risk factor are additive in their predictive power does the more risk factor on demonstrates the greater the risk of development of atherosclerosis and hence of CVD.

• Risk factors are often said to work together in a synergistic manner.

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     Family history:

• Familial hypercholesterolemia is caused by genetic abnormalities in lipoprotein clearance and lipid metabolism results in early death from disease.

    Age:

• Atherosclerosis develop over a span of years, a greater age allows for a greater period of time for the disease to develop.

• Heart disease is more prevalent in people over the age of 65 years.

• However the number of sudden cardiac death among people 15 to 34 has increased.

• As one ages, there are associated changes in endothelial control of vascular relaxation and in the elasticity of the arteries.

   GENDER:

• Males tend to develop  AS at a faster rate than females.

• The differences decline after the woman reaches menopause.

• The reason for the difference has to do with a protective effect of estrogen.

• The lifetime risk of development of ischemic heart disease after the age of 40 is reported to be one in two for men and one in three for women.

• Obesity:

• Obesity can be defined in several different ways when used for risk assessment but is most

•  commonly identified as a body mass index of 30 or greater.

• A  BMI of 30 or greater is associated with a proportionally higher all-cause mortality rate.

•  Alternatively obesity may be defined by waste their waist to hip ratio WHR.

• Waist girth alone  is a suitable predictor of risk.

• A waist girth of >102 cm for men or >88 cm for women is used as criteria for increased risk.

• Obesity is positively associated with dyslipidemia, hypertension, physical inactivity, and diabetes, all of which are also associated with AS.

    Dyslipidemia:

• Dyslipidemia refers to a lipid profile that increase the risk of atherosclerotic development.

• Typically dyslipidemia is a condition in which LDL levels are elevated and high density lipoprotein levels are low.

• LDL levels are the single strongest indicator of CVD risk.

• LDL are most heavily involved in  atherosclerotic process.

• Oxidation of the LDL causes this lipoprotein to be altered and can initiate damage.

• Oxidized LDL is more likely to be taken up into the atherosclerotic plaque.

• Higher the serum LDL levels the greater the risk of the initiation of an atherosclerotic plaque.

• In assessing risk for AS  one would use LDL as the primary marker if LDL is unavailable then HDL should be used as the indicator of risk.

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    Hypertension:

• An increase in BP increases the forces applied to the endothelial and cause the initiation of atherosclerotic lesion.

• Changes in pressure may also cause established plaques to rapture which not only can initiate and events such as  infarct but can also cause a proliferation of existing plaques.

    Physical activity:

• The increase in the patient was due to chronic positive caloric balance along with the associated epidemically, hypertension, and insulin resistance result in atherosclerosis.

• The exact mechanism by which physical inactivity increases atherosclerosis risk has not been identified. However increasing physical activity is known to impact several factors related to atherosclerosis by lowering blood pressure and triglycerides increasing HDL, improving endothelial function, and increasing platelet aggregation.

• Increased physical activity reduces the relative workload of any activity of daily living on the cardiovascular system.

    Atherogenic diet:

• Naturally diet plays a role in obesity which is directly and indirectly associated with atherosclerosis.

• A diet high in saturated fat, high in sodium, and low in fiber (westernized diet).

    Diabetes mellitus:

• The risk of death from cardiovascular disease in patients with type 1 and 2 diabetes is 2 to 4 time greater than those without diabetes.
•  Impaired fasting glucose and metabolic syndrome:

• Impaired fasting glucose is listed by many organizations as a separate and independent risk factor it does have a close association with other factors of the metabolic syndrome.

• Though there  is not universally accepted the definition, the metabolic syndrome is a constellation of metabolic risk factors including abdominal obesity, hypertension and prothrombotic state (a state in which the formation of blood clots is facilitated).

    Cigarette smoke:

• Environmental exposure to cigarette smoke has also been associated with the significant increase in CAD risk. In addition to the relationship noted for coronary AS process aortic and peripheral atherosclerosis are associated with smoking as well.

• Endothelial dysfunction, inflammation and modification of lipids that initiate and progress atherosclerotic development are affected by cigarette smoke.

• Endothelial relaxation is impaired by cigarette smoking. Nitric oxide which is primarily responsible for visualization of the endothelial is decreased in endothelial cells exposed to components of cigarette smoke such as nicotine.

• Cells exposed to blood from cigarette smokers demonstrate a decrease in the activity of the endothelial nitric oxide synthase enzyme.

• Inflammatory markers such as CRP are increased in response to cigarette smoke.

• The increased leukocyte count and pro-inflammatory cytokines that occur in response to cigarette smoking increase endothelial leukocyte interaction.

• Cigarette smokers also have significantly higher total cholesterol and LDL and lower HDL than non-smokers.

• More over, cigarette smoking increases oxidative modification of LDL which is a major step in the development of atherosclerosis.

•  What is main cause of atherosclerosis?

         Which are following diseases is also known as atherosclerosis?

        What are three symptom of atherosclerosis?