Cardiovascular disease is the leading cause of death in many nations today, accounting for almost a third of all deaths in the US, Australia and the UK.[1-3] Unfortunately cardiovascular disease rates are soaring in the developing world as well, and this is putting a strain on health systems globally. You may be surprised to know then that the World Health Organisation estimates that 80% of heart disease can be prevented with the right knowledge. Today's article is one in a series focusing on cardiovascular disease and associated risk factors. Enjoy!
What does cardiovascular mean?
There are three different types of muscle in the body: skeletal muscle (found in your arms and legs), smooth muscle (found in the walls of your organs), and cardiac muscle. Cardiac muscle is distinctly different from the other types of muscle in your body and is only found in your heart. It makes sense then that any word with the term 'cardiac' or 'cardio' in it refers to the heart in some way. For example 'cardio' exercise (also known as aerobic exercise) like brisk walking is exercise that works your heart e.g. by increasing your heart rate.
Of course, your heart does not work alone to supply blood to your body. It uses an intricate network of arteries and veins to deliver blood and oxygen to your muscles and organs. This network of arteries and veins is known as the vascular system.
Put the two words together : cardio + vascular = cardiovascular. So when anyone refers to anything to do with the cardiovascular system, they are referring to your heart and blood vessels. Cardiovascular disease then is any condition which affects your heart and blood vessels.
Just out of interest, if you hear someone speak of 'vascular' disease then they are referring to a condition that affects the arteries and/or veins predominantly. If they speak of 'cardiac' disease, then it's usually only a condition of the heart, though sometimes the terms 'cardiac disease' and 'cardiovascular disease' are used interchangeably in actual practice.
What types of cardiovascular disease are there?
The term 'cardiovascular disease' includes, but is not limited to ischaemic heart disease, heart attack, heart failure and stroke. Technically speaking, 'cardiac' diseases include congenital forms of heart disease (heart conditions present at birth) and other forms of heart specific diseases such as valvular disease and heart flutters and fibrillations. These conditions will not be discussed in this series of articles.
What are the biggest risk factors for cardiovascular disease?
You probably know that having high circulating cholesterol and high blood pressure puts you at risk for cardiovascular disease (CVD). But these are not the only factors that do this.
Being overweight, having a poor diet, being physically inactive, living a stressful life and smoking are also risk factors which can contribute to a CVD condition. While these other factors contribute to CVD risk partly by increasing a persons' blood pressure and blood cholesterol; strictly speaking they often contribute in other ways too.
For example smoking can lead to elevated carbon monoxide levels in your blood. Carbon monoxide replaces oxygen in the blood thereby reducing the amount of oxygen available for your body to use. To make up for the reduced concentration of oxygen in the blood, the heart works harder to get blood and oxygen pumping faster around the body. Of course the blood vessels that supply blood to the heart are also affected by carbon monoxide, resulting in reduced oxygen supply to the cardiac muscle. This means that not only does the heart have to work harder, it has to do this with less oxygen than normal i.e. under less than amiable conditions. Over time, this can lead to a cardiac condition known as 'heart failure'.
Cholesterol and cardiovascular disease
Interestingly, high circulating cholesterol can contribute to cardiovascular disease but it's the type of cholesterol and size of the particles that also matter.
Cholesterol is a waxy substance that is both made by your body and found in food. Your body makes cholesterol because it is essential for good health: you need it to be able to create essential hormones and cell walls. Fortunately, your body makes all the cholesterol it needs – it is self-subsistent in this way. This means that it does not need any more from food. If you get a little extra from food, your body can usually handle it. However if you eat a lot in your food over a long period of time, then your levels can increase steadily. This can be a problem if it is the wrong type of cholesterol.
Different types of cholesterol
You probably know that there is HDL (high density) cholesterol and LDL (low density) cholesterol. LDL cholesterol is often referred to as the bad cholesterol. This is because LDL cholesterol can be deposited in the walls of your blood vessels. HDL cholesterol on the other hand acts like a 'sweeper' cleaning up your blood vessels of the damaging LDL cholesterol. Up until recently we believed that all LDL cholesterol was damaging, however in recent times research has indicated that the size of the LDL particle matters and affects its potential to lead to cardiovascular disease.
In general, small LDL particles are more likely to deposit in the blood vessel wall than large particles. While genetics does play some role in the size of your LDL cholesterol, diet and lifestyle factors can help you increase their size, and thus reduce their potential for damage.
Why is cholesterol so bad?
When cholesterol deposits in the blood vessel walls it can lead to at least three different changes: stiffening, narrowing, and irritation and inflammation of the blood vessels.
All of these changes can lead to high blood pressure and reduced blood flow to different parts of your body.
This makes particular sense when you think of the blood vessels as being similar to a garden hose. If the hose is large in diameter, more water can flow through it. If there is a kink in the hose, water will build up behind the kink leading to increased pressure on the hose walls. At the same time, there is less water flowing through to the end of the hose and thus less water to water the garden with.
When this happens in the body, the parts of the body that are being slowly starved of blood become painful, particularly when they are worked or exercised. For example, people who have cholesterol build up in the blood vessels that supply blood to the cardiac muscle will develop angina (pronounced an-jhay-nah, also known as chest pain) as the condition develops. Initially angina is normally only experienced when the person is exerting themselves e.g. exercising; but as the condition develops it will lead to angina at rest.
Any tissues which are not supplied with enough blood are said to be undergoing some degree of ischaemia (pronounced ih-skee-mee-ah). If it is the heart tissue that's affected, the condition is known as 'ischaemic heart disease' or IHD, a form of cardiovascular disease.
What are plaques then?
The cholesterol and fat deposits in the walls are called plaques, and the process by which they form is called atherosclerosis. In many cases the plaques build up slowly and are stable. In these cases, the risk of a piece of the plaque breaking off to form a clot further up-stream in the blood vessel is usually low.
In some people however, these plaques become unstable and pieces will tear off or the plaque ruptures. This can lead to a blood clot forming at the site of the plaque, or further up-stream, leading to a completely block of blood flow to the tissue that the blocked blood vessel supplies.
When this happens in the heart, then the result is a heart attack. If it happens in the brain, the result is a stroke. If it happens in the lung it can be referred to as a pulmonary embolus. If it happens in the legs it is often referred to as an arterial thrombus if it is in the arteries of the leg, or as a venous thrombus (or DVT) if it is formed in the veins.
Want to know more?
Look out for our next article on blood pressure and blood sugar levels, and how they relate to your cardiovascular risk. But in the meantime, check out these questions and answers on cardiovascular disease, as well as these simple tips to prevent cardiovascular disease in children.
 Centers for Disease Control and Prevention (CDC), Heart Disease and Stroke Prevention
 Australian Bureau of Statistics, Heart Disease decrease over a decade
 British Heart Foundation, Mortality
 World Health Organisation, 2008 – 2013 Action Plan for the Global Strategy for the Prevention and Control of Noncommunicable Diseases