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Tests for the heart - what do they tell us?

Broadly speaking there are 3 things that can go wrong with the heart. 1. The heart is a pump and that pump may be faulty either due to congenital problem or an acquired problem. If the pump is in any way defective then not as much blood comes out of the heart and the body and all our vital organs will get less blood than they should and this could lead to harm. So cardiomyopathies, valve problems, myocarditis and previous heart attacks all cause a problem with the pumping function of the heart. 2. The pump needs a blood supply and even though the pump itself may be strong, there may be a developing problem with the blood vessels (the coronary vessels) which may block the blood vessel and therefore damage the heart. This is how heart attacks happen and therefore a comprehensive evaluation of the heart should always include some assessment of the heart arteries even if the heart as a pump looks strong 1. Finally the heart is also an electrically driven organ and therefore a malfunction of the electrics could lead to the heart malfunctioning as a pump even if it were strong and this could cause a problem. So virtually all the tests that we do on the heart are driven by the need to know more about the pumping ability of the heart, the heart arteries and the electrics of the heart. So today i wanted to talk to you about what each heart test tells us about these different aspects of heart disease 1. Tests that tell you about the heart as a pump 1. The most commonly used test to assess the heart as a pump is an echocardiogram. This is an ultrasound (a bit like the type that we use on pregnant women to look at the baby). An ultrasound will allow you to visualise the heart, measure the sizes of the chambers, assess the heart valves and work out how well the heart functions as a pump. If the heart has been left damaged, then that part of. the heart will be seen not to move like undamaged parts and this can therefore reliably tell us about persisting heart damage. This is important for 2 reasons: 2. -a) It tells us that the patient’s symptoms are not due to underlying heart disease and b) the heart will cope with stress much better than if it is damaged. An echo is easy to do, risk free and easily accessible. It is also unique because it works using the Doppler effect, you can get not only an anatomical evaluation of the heart but also physiological assessment. Nevertheless it does have some limitations: 1) it tells us about the present and the past but does not generally tell us about the future. 2) It is operator dependant and requires specialised machinery 3) The images you get may vary from patient to patient. 4) you dont see the heart in 3 dinmensions and because of the heart moves in many different ways, you are only getting a limited assessment of the heart and you dont get as good a sense of tissue composition A more advanced way of studying the heart as a pump is through cardiac MRI. Cardiac MRI offers some great advantages: 1. You get much better spatial resultion and therefore get much clearer images 2. You have no imaging constraints 3. MRI can tell you about tissue composition There are however problems with cardiac MRI as well. It is a super specialised discipline. It requires very expensive machinery. It is inherently uncomfortable for the patient as you have lie in a tight tunnel for up to an hour. Some patients with pacemakers and metal prosthesis cant be exposed to such strong magnetic fields. Overall though a normal cardiac MRI is even more reassuring than a normal echocardiogram. Are there any other easier tests that can tell you about the heart as pump?