 In this video, we are going to talk about heart failure. So how does a heart fail? Well, exactly how we fail in exams. We don't do what we are supposed to do, right? We don't study and that's the reason we fail. Same is with our heart. The heart do not do what it is supposed to do. That means pumping blood and supplying oxygen to all the body tissues. So when the heart fails to meet the oxygen demand of the body, we call it a heart failure. Now in a normal healthy heart, how do the heart meet the oxygen demand of the body? Well, by pumping blood out properly to all body tissues, right? So if there is any disturbance in the pumping out of the blood or in the total amount of blood that is being pumped out, we can expect a heart failure, right? So how do we measure or quantify the amount of blood that is pumped out of the heart? Well, we have already learned about it in our previous videos. It is called the cardiac output. Cardiac output is nothing but the total amount of blood pumped out by the heart per minute per ventricle, okay? And this cardiac output is directly proportional to the heart rate and stroke volume. Heart rate is the number of beats per minute and stroke volume is the amount of blood that is pumped out in each beat. So any slight change in the heart rate or the stroke volume will have direct impact on the cardiac output. And if the cardiac output decreases, heart failure, right? So most often the problem is seen in the stroke volume. Okay, here I want you to pause the video and think of what could be the probable reasons for the stroke volume to decline. Okay, now let's think of it this way. For the blood to get out of the heart, the ventricles should contract really hard, right? So the muscles of the ventricles, let's say the muscles here should contract really hard to push the blood out. So if any damage is caused to the muscles of the ventricles, then it would not contract hard enough to push out enough blood, right? So the first problem could be with the ventricular muscle. The next problem could be when the ventricles are filling with blood there is a possibility that not enough blood is poured into the ventricles or more than enough blood was poured in which was very difficult for the ventricles to push out. So it could be a problem with the filling of the ventricles. Now the third reason is an interesting one. When the blood is pushed out into the arteries the arteries also exerts a resisting pressure to the flow of the blood and if the resisting pressure is higher than the pressure poured in by the ventricles to push the blood out even then the stroke volume will decrease finally leading to the decrease in the cardiac output, right? So the third is the resistance by the arteries. So in all these three cases the heart fails to meet the oxygen demand of the body tissues and all of these can be a cause of a pre-existing or underlying heart condition. For example, a heart attack that could permanently damage a part of the heart muscle because of which it cannot beat well, right? And that can again reduce the cardiac output and cause a heart failure later in life. Okay, now that we know what a heart failure is let's talk about the symptoms. A person with heart failure will have extreme weakness obviously because of less oxygen reaching to the body tissues he will have less alertness and he will also have swelling in his face, abdomen, leg, hands and most body parts will also accompanied by a ton of different complexities but these are the main symptoms that a person with heart failure is seen to have. Now I'm sure you can understand about less alertness and weakness of the body because the body is not receiving enough oxygen but what can be the reason behind the swelling of the body? What do you think? Well, we know that the right part of the heart it receives deoxygenated blood from the body tissues and the left part of the heart receives oxygenated blood from the lungs. Now due to a heart failure the heart is not able to pump enough blood out to the body. It is receiving enough but it is not able to pump enough blood out. That's the reason the blood gets backed up both to the lungs and to the peripheral body tissues just like a traffic jam and that causes fluid buildup in those areas. Therefore, diagnosis shows that there is fluid buildup in the lungs, abdomen area in the legs and this fluid tends to move downward due to gravity when the person stands and it fills up the chest while the person sleeps. Therefore, a person with heart failure finds it really difficult to sleep. So, this was all about heart failure.