Coronary Heart Disease

Coronary Heart Disease

Overview

The most common form of heart disease is Coronary disease (CHD), and so this is the disease I will investigate. CHD refers to the build up of plaque in the arteries supplying oxygenated blood to the heart, also known as Atherosclerosis. The plaque is made up of cholesterol, fat and other substances found in the blood. When this build up of plaque occurs, the artery narrows, as shown in Figure. This will restrict blood flow to the heart, and so the heart will be deprived of oxygen and other essential minerals. If the heart is completely starved of these minerals, angina or even a heart attack may occur. Angina is chest pain, although it may also cause pain in the shoulders, arms, neck, and jaw. Angina will feel like pressure and tightening of the affected area. A heart attack also occurs due to blood deprivation. If blood flow isn’t restored quickly, parts of the heart will start to die. A heart attack can lead to serious health problems, or even death.

The Heart

The heart is a muscular pump, slightly larger than your fist. It pumps roughly 72 times a minute when resting, so that the body is supplied with the nutrients it needs to function. For example, the brain must receive oxygen and glucose, or else it will stop working. The wall of the heart is made up of 3 layers: the epicardium, myocardium and endocardium. The Cavity on the other hand is made up of four parts: two upper chambers (atria) and two lower chambers (ventricles). The right atrium receives blood from the body. It then passes this blood to the right ventricle through the right atrioventicular valve, which only allows blood to flow in this direction. Next the Right ventricle pumps the blood to the lungs to be re-oxygenated. The blood will then enter the left atrium through the four pulmonary veins. As before, blood flows in one direction through the left atrioventicular valve to the left ventricle, where it will be pumped to the rest of the body.

Causes

There are many lifestyle causes of CHD, including smoking and stress. However, For the purpose of this report I will be focussing on those related to diet. If excessive amounts of LDL cholesterol circulate in the blood, they may cause a build up of plaque in the arteries surrounding the heart. As mentioned before, this will limit the amount of blood travelling through the affected artery.

Excessive levels of sodium in the blood means the heart has to work harder to keep the right level of water in the body. This means that excessive sodium levels are the largest factor of a high blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps blood. High blood pressure accounts for 49% of CHD deaths. Therefore, excessive amounts of sodium can cause CHD.

A person will become obese if they consistently consume more calories than they burn. This means the person will have an increased body mass due to more body fat. An increased body mass means that more blood needs to be pumped by the heart throughout the body. This will cause extra strain on the heart. Obesity can also indirectly cause CHD disease through causing other diseases such as hypertension and diabetes.

Excessive consumption of alcohol is also a factor of CHD. Excessive consumption of alcohol can damage your kidneys and blood vessels, in turn raising your blood pressure. Secondly, alcohol can weaken the heart muscle. This is known as cardiomyopathy, and reduces the efficiency of the heart. The government guidelines state that consumption should not exceed 3-4 units for men, and 2-3 units for woman. This is equivalent to 1-1.5 pints of 4% alcohol beer.

Diagnosis

A doctor will diagnose CHD based on your medical and family history, a physical exam, your risk factors, and the results from certain tests. There is not a particular test that can diagnose CHD, so a collection of results from the following tests are used instead:

Electrocardiogram (EKG) – An EKG test records the heart’s electrical activity. As well as being simple and painless, the EKG can affectively detect the heart’s beating speed, rhythm and strength. Electrodes are used at the surface of the skin, and an external machine interprets the data.

Echocardiography (echo) – An echo test uses sound waves to create a moving picture of the heart. It will record the shape and size of the heart as well as how well it is working. The test will also show areas of the heart that aren’t contracting normally, and areas of low blood flow.

Stress testing – During stress testing, the patient will perform some sort of exercise (usually running on a treadmill machine) to make their heart work harder. If the patient has CHD, then this exercise will make the symptoms more obvious to the doctor. More oxygen is needed during exercise, and if the patient’s arteries are narrowed due to plaque, the patient may experience abnormal changes in heart rhythm, rate or blood pressure. Chest pain may also become obvious.

Chest x-ray – A chest x-ray uses ionising radiation to create images of the chest and its contents. This will allow the doctor to analyse the heart and decide whether there is anything wrong with it. Chest x-rays are among the most common films taken, as they are diagnostic of many conditions. However, exposure must be limited due to the ionising ability of x-rays

Electron-Beam Computed Tomography (EBCT) – EBCT is used to search for specks of calcium inside the arteries, called calcification. The scan takes roughly 30 seconds, and is a variation of conventional computed tomography (CT) X-ray scans long used to examine various parts of the body. EBCT scans are not hugely common as their accuracy is unknown.

Treatment

CHD can be treated effectively through lifestyle changes, medication and in some cases surgery. Since 2000 there has been a 40% reduction in deaths from CHD in people under 75. This shows that the evolution of technology has been vital in treating potentially fatal diseases. The most obvious treatment is down to the patient. If they are to attempt to stop, or at least reduce the amount of time they spend drinking, smoking and over eating, they will often find that the symptoms of CHD reduce. For some patients, it may be very difficult to quit the use of certain drugs such as alcohol. For others, it is easier. However, all patients will have access to information on how to be healthier. This includes diet-plans, which I will discuss in more detail later on.

Many medicines are used to either lower blood-pressure or widen arteries. Antiplatelets work by thinning the blood and stopping it from clotting. Statins work by stopping the formation of cholesterol. More LDL receptors are formed in the liver, which lowers the amount of LDL cholesterol in the blood. Beta-blockers work by stopping certain nerve impulses at the synapses. The ends of these nerves release a neurotransmitter called noradrenaline, which would normally stimulate the receptors on the end of the other nerve, called beta-adrenergic receptors. Beta-blockers work by blocking these receptors and so stopping them from being stimulated by the neurotransmitter.

In more serious cases, surgery may be the only option. There are three main procedures: Coronary Angioplasty (PCI) works by inserting a small balloon to push the fatty tissue in the artery outwards. A metal stent is then used to hold the artery open. Coronary artery bypass graft (CABG) works by inserting a blood vessel at the aorta, which works as a bypass route for the blood to flow through, instead of the narrowed artery. Finally, in the most serious cases, a heart transplant may be required to replace the damaged heart.