At first glance, the subject of heart disease can seem exceptionally complex – consisting of several different conditions, medical jargon and very scary sounding terminology. However when we really examine heart disease closely there are in general mainly 3 things that can go wrong with the heart and cause harm and if we know this then we are able to firstly understand the different conditions better but also get our head around why certain tests are done and what they tell us. This is important because there are many unscrupulous professionals and organizations which will offer expensive heart health tests which really dont tell us very much but other than cause unnecessary anxiety. I will go through these three things and the tests that give us insight into them.
- First and foremost, the heart is a pump and its job is to deliver oxygen rich blood around the body and to our vital organs. If the pump is unable to pump blood out (either because it is defective or because something is making it more difficult to pump blood out in some way) then less blood goes around and this can damage our vital organs and be dangerous.
Common conditions that can cause our pump to become defective are:
- A previous heart attack – a heart attack means that a part of the heart has died and therefore, the pump has in some way become weaker
- Heart valve disease – if our heart valves are abnormally narrowed then they make it a lot more difficult for the heart to pump blood out. If our valves are leaky then again, a smaller volume of blood is effectively ejected because some leaks back
- Cardiomyopathies – if the heart muscle itself is defective in some way then that makes it weaker. This includes conditions like familial hypertrophic cardiomyopathy, familial dilated cardiomyopathy etc.
- Infections and inflammation of the heart eg myocarditis will cause acute inflammation of the heart and therefore may compromise the pumping ability of the heart
- Conditions such as high blood pressure will make the heart work harder and as it does so it will become more muscular. As the heart becomes more muscular, it becomes stiffer and therefore does not fill with as much blood and therefore pumps less blood out. This is termed as diastolic dysfunction.
So what tests tell us about the heart as a pump?
- Echocardiography – We can use ultrasound to visualize the heart and look at how well it pumps. This is crude but is easily available and gives us a good basic visualization of the pumping abilities of the heart. A more sophisticated test would be an MRI scan because whilst on echo you will get a general overview.
- MRI has much better spatial resolution and therefore you can even detect smaller areas of abnormal or reduced motion i.e. damage. In addition, MRI can actually characterize abnormal tissue and tell us whether the areas of the heart that are not moving are due to inflammation or scar. The problem with both these tests are that they study the heart at rest and sometimes abnormalities may be picked up only when the heart is stressed and therefore combining these modalities with a stress test can be even more helpful and by far the best form of stress is exercise.
- Hence to my mind a really good way of assessing the heart as a pump is a test called an exercise stress echo. With this test, an echocardiogram is done at rest to study the pumping ability of the heart. The patient is then exercised on the treadmill and once peak stress is reached, the patient is taken off the treadmill and the heart is studied again by a repeat echo and the pumping function of the heart at rest is compared with peak exercise. If the heart looks strong at rest and gets even better at peak exercise then this indicates that the heart as a pump is strong.
2) The second thing that can go wrong with the heart is actually with the blood vessels that supply blood to the heart. Advancing age, bad genetics and bad lifestyle can all cause accelerated wear and tear and inflammation of the blood vessels. With time, fat and cholesterol can get trapped in the areas of wear and tear and cause plaque formation. The plaques can damage us in 2 ways. Firstly the plaque may continue to build up and cause actually restrict blood from getting to the heart muscle and this often presents with symptoms of chest tightness on exertion or angina. If the plaque gets so restrictive that no blood gets through then that leads to a heart attack which then damages the heart as a pump. The second way that plaque can harm us is that it may not even be particularly restrictive and therefore the patient has no symptoms but on one particular day a plaque may choose to rupture. When this happens, the body treats it as a fresh wound and a blood clot forms around it which inadvertently also has the effect of blocking the whole blood vessel, leading to a sudden heart attack. The majority of people who are above the age of 40 who die unexpectedly and suddenly do so because of a sudden plaque rupture.
The best way to know if there is plaque in the heart arteries is by a test called CTCA (CT coronary angiography). This is a non-invasive test which is done via a CAT scan and allows excellent delineation of the heart arteries and is perhaps the best test to exclude coronary artery disease.
Another test that can be done is invasive coronary angiography where a tube is actually inserted all the way up to the heart and the heart blood vessels are directly injected with dye under x-ray guidance. This is an invasive procedure and allows treatment to be delivered to any suspected narrowings. Cardiac CT is now widely available and to my mind the easiest way to know about the blood vessels of the heart.
3) The third thing that can go wrong with the heart is an electrical disturbance. The heart is an electrical organ and occasionally the electrics can choose to malfunction and the patient may develop a heart rhythm disturbance or a dysrhythmia such as AF or SVT or VT. Unfortunately it is very difficult to predict a heart rhythm disturbance. You can only diagnose it in retrospect. However if we know that the heart as a pump is strong and the blood supply to it is unaffected then the heart will generally cope well with a heart rhythm disturbance and usually the patient will remain well enough to get to hospital and get it checked out. Heart rhythm disturbances are best diagnosed by an ECG during the heart rhythm disturbance. As many heart rhythm disturbances terminate by the time that the patient makes it to hospital, prolonged heart monitoring is often required to capture the heart rhythm disturbance. Even if you are unable to catch it, just knowing that you have a strong pump and the pump has an unrestricted blood supply tells you that the heart rhythm disturbance is unlikely to be dangerous.
So in essence, I would say that the 2 best tests to get a really good understanding of what is going on with your heart are 1) a stress echo and 2) a cardiac CT. 3) some kind of prolonged ECG heart monitoring if you are having palpitations.
Just before I leave you, I would like to say one more thing. It is only worth knowing about something if you are able to do something about the findings otherwise all it can do is just generate a lot of unneeded anxiety. So if you lead a bad lifestyle and are worried about your heart then it’s only worth having the test if you will be able to use the findings to change your lifestyle (and one could argue that perhaps you should do that anyway regardless of the test but the test may provide the necessary motivation. Another example is that your GP may be recommending statins based on your cholesterol and you feel uncomfortable with taking them – in that case knowing about the presence of plaque in your heart arteries can be exceptionally helpful as you could argue that if there is no plaque then you don’t need it.
As I mentioned earlier, many places offer these heart health checks which include a blood pressure measurement and a cholesterol etc and i am not sure these tests are that helpful. It is far more helpful to look for harmful processes rather than numbers, many of which are poor surrogates for those processes that you can now directly visualize.
I hope you found this useful and I would love to hear your thoughts.
Keywords: Echocardiography; Cardiac MRI; tests for the heart; heart disease; heart health; yorkcardiolog; Dr sanjay gupta