The cardiovascular system (comprising of the heart, arteries and veins) isessential for keeping homeostasis balanced throughout the body. The heart works as a pump to push blood containing oxygen and nutrientsthrough the extensive network of arteries and arterioles to replenishorgans, tissues and respiring cells, once replenishment has taken placewaste products and carbon dioxide are removed and taken back to the heartin the blood stream through veins and venules to be redirected through thepulmonary circulation back to the lungs to be deoxygenised (see appendix1).
The heart also needs to be replenished with oxygen rich blood to survive;blood is supplied to the heart by the coronary circulation (see appendix2). Just like any other organ in the body, the heart and surrounding vesselsare susceptible to disease. One of these many diseases is Coronary HeartDisease. Coronary heart disease is the most common cause of premature death in theUnited Kingdom. On average every year 110. 000 people die from heartrelated diseases, whilst 300.
000 people have heart attacks and more than1. 4 million suffer from angina, (British Heart Foundation 2001). CHD iscaused by a number of “risk factors” (risk factors are issues that cancontribute to a disease). Risk factors associated with CHD are high bloodpressure (hypertension), cigarette smoking, alcohol, physical inactivity,obesity (being overweight), and high blood cholesterol. As fatty foods are consumed and digestion initiates, saturated fats fromthe digested food is broken down by the liver to produce cholesterol.
Passing into the bloodstream the cholesterol combines with proteins tocreate “lipoproteins”. Lipoproteins are used for transporting numeroustypes of lipids to and from the cells. Lipoproteins are divided into twocategories, high density lipoproteins (HDL) and low density lipoproteins(LDL). HDL’s remove excess cholesterol from the cells and transports it tothe liver to be destroyed, whereas LDL’s are responsible for supplyingcells with cholesterol.
The cells in the body have LDL receptors attachedto them. Once inside the cell the LDL is broken down and cholesterol isreleased to fulfil the cells requirements. When the cell has adequatecholesterol to function a negative feedback prevents the cell from makingnew LDL receptors. Unfortunately CHD can also be a genetic disease,thought to be caused by a mutation in the apolipoprotein B (main protein inthe low density lipoprotein group). The mutation causes insufficientproduction of receptors and therefore high levels of cholesterol arereleased increasing the susceptibility to CHD.
With the combination ofhigh levels of LDL and raised levels of homocysteine (an amino acid,building blocks that make up protein) derived from methionine another aminoacid which is found in eggs, milk and meat atherosclerosis occurs (seeappendix 3). Atherosclerosis is caused by a build-up of cholesterol and fatty substanceson the inner wall of the artery, beginning as fatty streaks which graduallydevelop to form lumps known as plaques (see appendix 4). Raisedhomocysteine levels damage the lining of the artery whilst plaques assistthe walls of the artery to thicken and harden therefore the lumen of theartery narrows. This results in myocardial ischemia (poor blood flow tothe heart) and the oxygen needs being suspended (hypoxia).
As the heartsrequests for oxygen surpass the amount available the heart omits warningsigns in the form of tightening and pain in the chest, sometimes extendingto the upper extremities, lumber area and abdomen, this is clinicallyreferred to as stable angina. In extreme cases of atherosclerosis theplaques in the misshapen coronary artery affect blood flow resulting in thedevelopment of blood clots (thrombus) When a thrombus occurs (see appendix5), it blocks the artery triggering an attack of unstable angina, if theheart continues to be starved of oxygen for more than a few minutes theheart muscle begins to die resulting in myocardial infarction (heartattack). Myocardial infarction can contribute to total starvation of theheart resulting in congestive heart failure and inventively death. Some heart attacks can be looked upon as warning signs and that a change inlifestyle is required. There are many prescribed medications available toreduce the risks of heart failure, for example; aspirin is used to reducethe stickiness of the platelets therefore reducing the risk of blood clots(thrombus).
Diuretics (which target the kidneys to increase excretion ofwater in the urine) these reduce blood pressure and build-up of water intissues (oedema). Lipid lowering drugs (statins) raise the amount of highdensity lipoproteins (good cholesterol) and lower low density lipoproteins(bad cholesterol), these work by inhibiting the enzyme involved in thesynthesis of cholesterol. The administration of these drugs are designedto be incorporated into a newly modified lifestyle. Practitioners will advise CHD patients to reassess their former standard ofliving and introduce an alternative healthier option. To achieve anoverall healthy eating plan the patient should endeavour to consume fivefruit and vegetable portions daily, use only low fat or fat-free dairyproducts, include six wholegrain foods (found in cereals and bread), eatonly lean meat and remove skin from poultry, try to include two portions offish weekly, especially fatty fish (sardines, pilchards) containing largeamounts of omega 3 oils as it helps to reduce the risk of CHD and improvesthe chance of survival after a heart attack.
Limit sugary foods and foodswith no nutritional value (fast food fries), cut down on trans-fats(partially hydrogenated vegetable oils) these consist of pastries, crispsand some margarines. Avoid using sodium (salt), limit alcohol intake toone drink a day or if possible cease drinking alcohol altogether. If a CHD patient follows a sensible diet, controls other risk factors,(smoking and alcohol) partakes in exercise (which helps to lower andcontrol blood pressure, and combined with a healthy diet increases physicalfitness) and takes possible medication prescribed by the doctor (somepatients may not be administrated any medication), there is a strongpossibility the patient will carry on to have an extended healthier life. Although the majority of all patients will need to attend the doctorssurgery for regular health checks (blood cholesterol tests, blood pressurechecks and weight checks) to clarify the body is still responsive to thealternative changes. In some CHD patients modifying risk factors are notenough and surgery is performed to combat chances of heart failure. Surgery of the coronary arteries isreferredtoasPercutaneousTransluminal Coronary Angioplasty (PTCA).
Several types of procedures maybe performed ranging from balloon angioplasty (a small balloon insertedinto the blocked artery to widen the artery for blood flow) (see appendix6); to coronary artery bypass (patches of veins and arteries from anotherpart of the body are removed and placed into the heart in an attempt tobypass the blocked arteries) (see appendix 7). All surgical procedureshave the chance of failure especially with the delicate tissues of theheart. The fundamental key to coronary heart disease is prevention. People livein ignorance about disease and only show signs of interest if theunthinkable happens to them or a family member.
If the whole populationwas to be forewarned about the risk of CHD or coronary heart failure at anearlier age the consequences could be lessened. Children should beeducated on how diseases can affect the body and also how to avoid them;they should be taught how to look after their bodies, physically throughexercise, eating healthier diets and the avoidance of smoking and drinking.