Cardiovascular disease Flashcards
Your heart is a muscular pump which generates the blood pressure needed to keep the blood flowing. This can be measured using a piece of equipment called
a sphygmomanometer or digital blood pressure meters which take the readings automatically.
The first number is the higher pressure caused as the left ventricle contracts to push blood out of the heart. Doctors call this the systolic pressure.
The lower value is the pressure in the arteries during the time that the heart is filling with blood. This is the diastolic pressure.
Doctors always give blood pressure as two readings.
A healthy person's normal pressure might be "120 over 80 mm of mercury (mmHg)".
When you are relaxed, your resting blood pressure is relatively low. When you are active your blood pressure rises to supply blood faster to the hard-working muscles. This is caused by the body producing
adrenaline, the hormone which prepares your body for 'fight or flight'.
A person has high blood pressure, called
hypertension, if their resting blood pressure is higher than about 140/90mmHg. In the United Kingdom over 10million people have hypertension.
Hypertension is a health problem because
it puts great strain on the heart, which can lead to serious heart disease. It can also cause tiny blood vessels to break. If this happens in the brain it leads to a stroke. A blood clot forms and deprives a part of the brain of blood and therefore of oxygen. This damages nerve cells and can lead to paralysis or even death.
........ can be genetic but it is often caused or made worse by lifestyle choices. Being overweight, smoking and not taking exercise all increase the risk of hypertension.
Often it is possible to lower your blood pressure by taking simple measures such as losing weight, taking more exercise and eating a balanced diet containing lots of fruit and vegetables, low levels of saturated fat and salt and limited amounts of alcohol.
If lifestyle measures do not help lower the blood pressure, medicines called beta-blockers can be given to slow the heart rate and reduce the force of contractions. This helps to reduce the blood pressure. Medicines known as ACE-inhibitors can also help by opening up the arteries and veins to allow the blood to flow more easily.
Low blood pressure can be a sign of heart failure or may be due to a dramatic loss of blood due to severe bleeding after something like a road accident. If it is not treated quickly, oxygen is not delivered to the brain and this is fatal. At the scene of a car accident, fluids may be put in to the blood stream, using an intravenous drip, to help maintain the blood pressure.
Cardiovascular diseases include:
- High blood pressure (hypertension)
- Atherosclerosis - this is when a fatty deposit or plaque builds up inside an artery so the artery wall becomes harder and the gap for the blood to flow through gets narrower.
Atherosclerosis is the cause of many serious cardiovascular conditions including:
Atrial fibrillation is a form of arrhythmia
A heart attack
Coronary artery disease
- Coronary artery disease is when
atherosclerosis takes place in one of the coronary arteries. This reduces the blood supply to the heart muscle itself. The lack of food and oxygen can cause problems including pain and shortness of breath when you exercise, this is known as angina.
- A stroke
happens when a blood clot forms in one of the blood vessels supplying the brain with food and oxygen. This is often the result of atherosclerosis in the vessels. If a blood vessel in the brain breaks and bleeds this can also cause a stroke. Bleeding in the brain is often the result of high blood pressure.
- A heart attack
results if one or more branches of the coronary artery become completely blocked by plaque or by a clot which forms as a result of the plaque. In a heart attack part of the heart muscle is starved of oxygen. In a severe heart attack the patient may die. About 27% of all deaths in countries such as the UK are caused by coronary heart disease.
- Atrial fibrillation is a form of arrhythmia when
the natural rhythm of the heart is disturbed. The atria beat very fast and irregularly so they do not empty properly.
- Genetic problems with the heart such as long QT syndrome
can cause serious problems. This is the most common cause of death due to heart problems in teenagers and young adults.
Angiograms show up a blocked coronary artery
ECG (electrocardiogram). This machine gives images of the electrical activity of the heart. Doctors can use this to see how the heart is beating.
Factors affecting cardiovascular disease
- It may run in the family - there is a genetic tendency to develop CVD such as hypertension
- Age - the older you are, the more likely you are to suffer from CVD
- Being male - men are more likely to suffer from CVD than women, particularly before women go through the menopause
- Being overweight - obesity is closely linked to CVD (see graph below)
- Smoking - smoking narrows and hardens the arteries which causes CVD
- Lack of exercise - if you don't exercise your cardiovascular system is not very fit and your risk of disease increases - your risk goes up
- High blood cholesterol - this may be genetic or related to the amount of fat in the diet.
The relationship between obesity and coronary heart disease is shown in the graph below.
Preventing cardiovascular disease
- Keep your weight down - or lose some weight if you know you are overweight or obese
- Stop smoking - or better still never start
- Take regular exercise - even walking from place to place helps
- Watch your blood cholesterol levels by eating a low fat diet and having the levels tested regularly
Treating cardiovascular disease
are special mesh tubes which can be inserted into an artery affected by atherosclerosis. The stent is opened up using a tiny balloon which inflates. This squashes the fatty deposits and opens up the blood vessel so the blood can flow freely again. Stents can be put in place in the coronary arteries by feeding them in through the blood vessels in the leg. This doesn't need an operation so it is faster, safer for the patient and cheaper. Some stents are now made which contain medicines which reduce the risk of blood clotting even further.
medicines which lower cholesterol levels in people who cannot control them by diet alone. They also help to balance the amounts of good and bad cholesterol. They prevent many strokes and heart attacks.
are medicines which help stop the blood clotting too easily. They are useful for preventing clots forming when people are at risk of heart attacks or strokes - for example if they suffer from atrial fibrillation.
- Bypass surgery
replaces blocked coronary arteries with healthy blood vessels from somewhere else in the body, often the legs or the chest. The surgery restores the blood supply to the heart muscle and prevents angina pain and heart attacks. This surgery involves opening up the chest of the patient to get at the heart so it takes a long time, costs a lot of money and carries a risk to the patient. In recent years doctors often avoid the need for bypass surgery by the use of stents.
- Artificial pacemakers
are put into the body with two wires running to the heart. Their job is to take over the function of the natural pacemaker region if it goes wrong. The pacemaker has a battery and sends a small shock into the heart muscle at regular intervals to stimulate it to beat normally.
Treating a heart attack
doctors try to get them stable enough to have bypass surgery, stents or treatment with medicines to keep them alive and well.
Defibrillators can save lives
- Clot-busting medicines (thrombolytic medicines)
are given to people to dissolve the clots in the coronary arteries that are causing a heart attack (or stroke). The sooner they are given, the more effective they are.
- If the ventricles of the heart stop pumping blood properly, or the heart stops completely, a defibrillator can be used.
This gives the heart an electric shock and may start it beating again in a normal rhythm. Defibrillators are often used by doctors or paramedics in ambulances and hospitals. However every minute that passes after a cardiac arrest reduces the chances of survival by 14%. Automated defibrillators are sometimes found in pubs, swimming pools and shopping centres. They can be used by members of the public as they give clear automatic instructions about what to do to save a life.