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Transkrypcja filmu video (w języku angielskim)
- [Voiceover] So heart failure is a pretty broad disease. It's essentially defined as this inhability to meet the body's demands, right? But, how do we go about diagnosing that or how do we figure that out? Well, there's a couple of ways that doctors can do this. And the first group of ways is just by imaging the heart. Or, essentially just looking at it. So what we might do is we might take an x-ray or the chest area. Now, x-rays use this electromagnetic radiation that's blocked by certain structures more than others. So, that's why you might see the bones show up as white. And then, other organs might show up as gray. So, this lets doctors kind of visualize the current state of both the heart and the lungs. So, usually they're looking for the outline of the heart, right? And one thing they might look for in the heart is any sign of enlargement where the heart just looks bigger than it normally should. Because remember, with both systolic and diastolic failure, the heart can actually get bigger. And this can sometimes be seen on x-ray. And then another thing that doctors might take a look at is your lungs. Because remember with left-sided heart failure you can have this congestion or a fluid build up in your lungs. And this fluid is sometimes visible on x-ray. And this can give doctors a clue as to both how severe the heart failure is and also, whether is left-sided or not. So that was x-rays, but another diagnostic imaging technique that we sometimes use, and it's probably actually more common for heart failure, is the echocardiogram. And so, if we take a look at the first part of this word, echo, it kinda clues into its meaning. This diagnostic uses sound waves actually instead of electromagnetic radiation like with x-rays. Specifically you have this thing called the transducer that sends out sound waves. And then it waits for the sound waves to bounce back or to echo. And by knowing certain properties of the tissues, like how fast the sound waves are gonna move through them, we can get this image and even sometimes a real-time video. And so since you can see the heart moving via this video, this tests are super valuable for measuring the heart's pumping ability. Or your ejection fraction. Which you know, if we remember, it's this percentage of blood ejected from the heart with each beat. And by measuring the ejection fraction the echocardiogram is a super useful tool for doctors to figure out if its diastolic failure or systolic failure. Because with diastolic failure, remember that you can have a preserved ejection fraction. Whereas with systolic failure, your ejection fraction is typically a lot lower than normal. Alright, so besides imaging techniques, another thing we can look at is the blood test. With a blood test we're looking for certain substances that are secreted or associated with heart failure. And one in particular that we're going to focus on is called B-type Natriuretic Peptide. And that's a mouth-full so I'm just gonna refer to it as BNP. So BNP is this really important indicator because it's secreted by the heart's ventricles in response to this excessive stretching of the muscle cells and changes in pressure in the ventricles. Remember that with heart failure the pre-load or the pressure in the ventricles tends to increase right? Which causes the muscles to stretch more and the heart to enlarge. So when this happens, the ventricles secrete this BNP into the blood. So the more severe the heart failure, the more stretch in the ventricles and the more BNP that's secreted. And so it makes sense that if we take a small sample of blood we might be able to analyze it and see how much BNP is present. So BNP levels below 100 pg/ml of blood indicates no heart failure. And this is a really small amount but it's still measurable. And BNP levels between 100 and 300 pg/ml might suggest the presence of heart failure. Between 300 and 900 it might be considered mild to moderate heart failure. And then above 900 pg/ml would indicate a severe case of heart failure. But beyond Imaging and a Blood Test, the doctor will often use a couple of classification systems to describe the severity of the symptoms. Basically so they can get an idea on how best to treat each individual patient. And the first is the Stress Test which is also know as The New York Heart Association Functional Classification. This looks at how well you respond to physical exertion. Because we know that with more activity and exertion, your body demands more blood right? So depending on how well your heart can respond to increasing demands by increasing this activity, we can start to understand how severe the heart failure is. So the doctor might monitor you while you either walk or a treadmill or ride a stationary bike. And the first class or I is no limitation to physical activity. Meaning that this activity doesn't cost any out of the ordinary fatigue, palpitations or shortness of breath. Class II is some limitation to physical activity. Meaning that you might be comfortable at rest but any normal physical activity results in some symptoms of heart failure. Class III however is a lot of symptoms during physical activity. But still no symptoms at rest. Finally class IV indicates a complete inhability to undertake really, any physical activity without feeling no symptoms. And furthermore those symptoms even occur at rest. So the second classification system is The American Heart Association Stages of heart failure. And this one is more defined at the objective level bye the amount of structural heart disease that's present with each patient. So with Stage A, the patient might be at risk for heart failure. But there aren't any structural changes to the heart. So at this point it might be a patient with maybe diabetes or high-blood pressure. But there haven't been any changes to the heart in response. And there aren't any symptoms of heart failure. In Stage B, patients have some sort of measurable structural heart disease. So, like maybe their ejection fraction is lower or they have an enlarged chamber. But with Stage B, symptoms of heart failure still haven't developed. At Stage C, both a structural heart disease has occurred and symptoms of heart failure are present. And finally, Stage D indicates and advanced level of heart disease and continued symptoms of heart failure. And this level usually requires aggressive medical therapy and intervention. So using these two systems together, doctors can get an idea on how best to treat each patient based on both their class and stage or heart failure.