Coronary Heart Disease (CHD) otherwise known as Ischemic and Atherosclerotic Heart Disease is the result of a variety of factors such as the build up of fatty materials, calcium, and athermanous plaque within the walls of the arteries that acts as the supply for the myocardium of blood. The arteries supplying the heart are divided into three different parts, the ‘inner layer’ which is elastic and made up of Squamous Epithelium cells. Also, a ‘middle layer’ made up of connective tissue and smooth muscle, and an ‘outer layer’ made of connective tissues.
In CHD, the endothelium layer becomes damaged, constituted by a variety of lifestyle and genetic deficiencies, and results in a build up of cholesterol in the middle layer of connective and muscle tissue. As a result, these cells become known as ‘foam’ cells that swell within the cholesterol – thus narrowing the lumen. This is known as an ‘arthroma’ or ‘atherosclerosis’ of the lumen, where lipoproteins from the blood have accumulated to form a mass of fat swollen cells in the endothelium.
?If coronary artery becomes blocked, the cardiac muscle that it supplies will become short of essential nutrients and contract irregularly ‘. This arthroma pushes the endothelium lumen, and becomes known as a ‘plaque’ which can seriously narrow the lumen. A plaque is basically an area of muscle cells and fibers, where the narrowing of the lumen results in the reduction of blood to the myocardium, and can induce strains of angina – a form of ischemia. If large areas of the heart are ischemic, then this causes the irregularity of systole and diastole of the heart.
This, therefore constituting a reduction of oxygen to the myocardium can induce far more dire consequences upon the heart, where in critical scenarios a myocardial infarction or sudden cardiac arrest could ultimately follow. If plaques are overly large, it is possible for part of the plaque to break off, causing a clot within the artery. This ’embolus’ could restrict blood flow to the heart, and could also be the ultimately fatal cause of sudden cardiac arrest or myocardial infarction. ?Coronary heart disease (CHD) is a preventable disease that kills more than 110,000 people in England every year’.
There are a variety of factors affecting the development of CHD, the perhaps most apparent of these being environmental factors and self inflicted lifestyle factors. For example, tobacco smoking is a huge contributor to the development of CHD, where smokers are more than twice as likely to have a heart attack than non-smokers . The development of CHD is four times as likely for a person than smokes, than a person who does not. Carbon Monoxide and nicotine are probably the most important substances in tobacco smoke which affect the heart .
Nicotine acts as a stimulant ? a vasoconstrictor, which raises heart rate and thus the blood pressure due to the narrowing of arteries. This contributes to the development of CHD. Research into nicotine also shows that it can contribute to the development of thrombosis, raising the risks of myocardial infarctions. Carbon Monoxide inhaled from the tobacco smoke can reduce the ability for red blood cells to carry oxygen pigments, as it latches onto the hemoglobin pigment of red blood cells which enables the transport of oxygen, and therefore deems it inoperable.
Cholesterol ? another major contributor to the development of CHD is further induced by tobacco smoking as it is known to increase blood cholesterol levels. Smoking is also the cause of many other cardiovascular diseases, and the best lifestyle option to prevent these is to avoid smoking tobacco. Cholesterol is another major contributor to CHD, the higher the blood cholesterol level ? the higher level of risk. Cholesterol is a soft, waxy substance when soaked in alcohol and is transported in the blood as a soluble lipoprotein.
These lipoproteins are divided into two separate areas consisting of beneficial and less beneficial categories. Low density lipoproteins (LDL’s) are high in cholesterol and therefore contribute to the development of atheromas and are considered less beneficial. High density lipoproteins (HDL’s) are low in cholesterol and are not thought to contribute to the development of atheromas, and instead counteract the effects that LDL’s ultimately produce; therefore making them less dangerous to health.
It is cholesterol that congregates beneath the ruptured endothelium layer of the artery and turns the cells into a mass of ?foam cells’, and so the consumption LDL’s ought to be kept to a minimum by eating a healthy diet, although some levels of cholesterol for cell development.
Another major contributor to the development of CHD is blood pressure, where high blood pressure increases the heart’s workload. As mentioned before, this can be influened by tobacco smoke, where nicotine acts a vasoconstrictor narrowing the arteries and raising the blood pressure. However, high blood pressure can cause a variety of disorders, ranging from anuerisms to the damage of the endothelium layer ?thus conributing to CHD.
High systolic pressure is most significant in this regard. ?Many factors lead to hypertention, these include stress, obesity, ecessive consumption of alcohol, a high intake of sodium and smoking tobacco’ . It is normal to have a short term raised high blood pressure, or during vigerous exercise in order to compensate the muscles for their increased need for oxygen through the increment of cardiac output. Over a long term perdiod in a person who has a high blood pressure, their condition would be referred to as hypertention.
Hypertention has an increased risk of CHD, as the arteries respond to the high blood pressure and therefore begins to narrow the lumen. The ways to avoid hypertention consist of avoiding the mentioned causes, and also drugs prescribed by doctors such as Beta Blockers can lower blood pressure. Obesity is an ever growing factor in both Britain and the USA, and the condition brings with it a variety of complications. For example, the excess body weight can contribute to a raised blood pressure (hypertention), and has associations with the development of diabetes and high cholesterol.
Diabetes Mellitus contributes to CHD, or otherwise Hyperglycemia, as excess levels of glucose can damage the epithelium layer. This therefore emphasises the risk of CHD and can be avoided by losing weight to a healthy level with a lower risk of developing high blood pressure. Lack of exercise is also a factor that can lead to obesity and also needs to be taken into account to ensure a healthy lifestyle and diet. Other important indirect factors that affect the development of CHD consist of age, geder and inheritance factors. ?Men older than 45 years, and women older than 55 years are at increased risk for coronary disease’.
The male gender has an increased risk of CHD, as females have hormones that naturally decrease blood pressure. ?About 80% of people who die of CHD are aged 65 or older’. Also, CHD is a hireditory factor that is passed through the family by inheritance, as people with parents who developed CHD are far more likely to develop it themselves. Racial and cultural inheritance are also factors putting people at higher risk, not necessarily through the genetic gene pool, but rather environmental factors such as stress that could ultimately lead to hypertention.
In conclusion, CHD is a risk posed by many inherited and self inflicted factors, and unsurprisingly enough makes it one of the biggest killers in the UK. The majority of factos affecting the development boil down to the habits of the people that suffer from CHD, and can easily be rectified by quitting smoking, eating a healthier diet, avoiding prolonged stress and obesity. Many of these factos are interlinked, where avoiding inactivity can ultimately avoid obesity and lower blood pressure. However, some of the developments are out of bounds and are due to permanent dysfunctions such as Diabetes Mellitus, also the affects of ageing and gender.
Bibliography . British Heart Foundation, Heart Information Series No. 11 ? The Heart, reprinted 4/97 . British Heart Foundation, Heart Information Series No. 10 ? Smoking & Your Heart, reprinted 1996 . Class Notes ? Defining CHD and the risk factors . AQA Biology: A New Introduction to Human Biology, Hodder & Stoughton, Bill Indge, Martin Rowland, Margaret Baker. Pages 203-5. ISBN: 0-340-78166-1. . http:/en. wikipedia. org/wiki/Coronary_heart_disease Accessed 23/01/2007 . http:/www. emedicinehealth. com/script/main/art. asp? articlekey=58675&pf=3&page=2 Accessed 23/01/207.