- [voiceover] so heart failureis a pretty broad disease. it's essentially definedas 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 ofways 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 iswe might take an x-ray or the chest area. now, x-rays use thiselectromagnetic radiation that's blocked by certainstructures more than others. so, that's why you might see the bones show up as white. and then, other organsmight show up as gray. so, this lets doctors kind of visualize the current state of boththe heart and the lungs.
so, usually they're looking for the outline of the heart, right? and one thing they mightlook for in the heart is any sign of enlargement where the heart just looks bigger than it normally should. because remember, with bothsystolic 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 withleft-sided heart failure you can have this congestion or a fluid build up in your lungs. and this fluid issometimes visible on x-ray. and this can givedoctors a clue as to both how severe the heart failure is and also, whether is left-sided or not. so that was x-rays, butanother diagnostic imaging
technique that we sometimes use, and it's probably actuallymore 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 electromagneticradiation like with x-rays. specifically you have thisthing 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 certainproperties of the tissues, like how fast the sound wavesare gonna move through them, we can get this image and evensometimes a real-time video. and so since you can see theheart moving via this video, this tests are supervaluable for measuring the heart's pumping ability.
or your ejection fraction. which you know, if weremember, it's this percentage of blood ejected fromthe 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 failureor systolic failure. because with diastolic failure, remember that you can have apreserved 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 lookat is the blood test. with a blood test we'relooking for certain substances that are secreted orassociated with heart failure. and one in particular thatwe'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 bythe heart's ventricles in response to this excessivestretching of the muscle cells and changes in pressure in the ventricles. remember that with heart failure the pre-load or thepressure 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 between100 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 acouple of classification systems to describe the severity of the symptoms. basically so they can get an idea on how best to treateach individual patient. and the first is the stress test which is also know as
the new york heart associationfunctional classification. this looks at how well yourespond to physical exertion. because we know that withmore activity and exertion, your body demands more blood right? so depending on how wellyour heart can respond to increasing demands byincreasing this activity, we can start to understand howsevere 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 thisactivity doesn't cost any out of the ordinary fatigue, palpitations or shortness of breath. class ii is some limitationto physical activity. meaning that you mightbe 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 indicatesa complete inhability to undertake really, any physical activity without feeling no symptoms. and furthermore thosesymptoms even occur at rest. so the second classification system is
the american heart associationstages of heart failure. and this one is more definedat 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 structuralchanges to the heart. so at this point itmight be a patient with maybe diabetes or high-blood pressure.
but there haven't been anychanges to the heart in response. and there aren't anysymptoms of heart failure. in stage b, patients have some sort of measurable structural heart disease. so, like maybe theirejection 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 structuralheart 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 medicaltherapy and intervention. so using these two systems together, doctors can get an idea onhow best to treat each patient based on both their classand stage or heart failure.