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Current time:0:00Total duration:8:49

Video transcript

let's talk about ventricular fibrillation also known as v-fib this is an abnormal deadly heart rhythm where the ventricles which I'm outlining right here these lower chambers of the heart the ventricles Loosli you built the ability to contract and circulate blood to the rest of the body and that's why v-fib is so deadly so over here we have a heart diagram looking at the inside of the heart just like we did on the left but this diagram on the right highlights some of the important structures in the electrical conduction system and I've taken out the big vessel so that way you can get a better view of the inside of the heart so in a normal heart the electrical conduction starts at the sinoatrial node also known as the SA node so final atrial SA node the signal travels from the SA node down to another structure called the atrioventricular or AV node so that stands for atrial ventricular or AV node from the AV node the signal goes down to the ventricles and signals to the ventricles and makes a ventricular cells and the walls contract when these walls contract that's when blood is pushed out to the rest of the body now in v-fib the signal in the ventricles is no long coordinated this might be because you have some sort of severe oxygen deprivation or because you have some sort of abnormality in conduction but for whatever reason you lose coordinated signaling in the ventricles instead you have this rapid random and chaotic signaling this chaotic signaling leads to the ventricular walls spasming and when the ventricular wall spasm blood can't be circulated through the body it just stays here in the heart if you're not circulating blood to the rest of the body you're depriving all of the other organs of oxygen another way to think about this is think about if you were squeezing a tube of toothpaste so here you have a hand squeezing a tube of toothpaste and you can imagine that if you squeeze with all your fingers at the same time you're going to get the most toothpaste out so if you coordinate all your fingers to squeeze at the same time you're going to squeeze out the most toothpaste as opposed if you squeezed your pinky and then your index finger and then your thumb you're not going to squeeze out a bunch of toothpaste this is the same idea as ventricular fibrillation you lose this coordinate contraction and this coordinated squeeze to distribute blood to the rest of the body and instead you have random firing of muscle cells leading to this spasm and you're not going to push out a lot of toothpaste or blood to the rest of the body if v-fib isn't reversed immediately through electric shock you're going to have permanent brain damage and death because the brain in the body aren't getting enough oxygen a person whose heart is in v-fib is not going to be conscious since they have no blood circulating and you won't be able to feel a pulse pulses are made by forward movement of blood to the vessels so if you have no.4 movement of blood to the vessels you're not going to have a pulse sometimes right before someone collapses from particularly for relation they might can complain those signs or symptoms of a heart attack like chest pain or numbness or tingling in their left arm and that's because the heart is getting deprived of oxygen since the heart's not circulating blood to the rest of the body it can't circulate blood to the heart itself and some skin isn't getting oxygenated blood you might see the skin turn pale or even a blue color this is also known as cyanosis that's the blue color skin we are not circulating oxygen through the body an EKG is someone in v-fib looks like this you're going to see coarse squiggly lines this is because you lose a smooth signaling from the SA node to the AV node to the ventricles instead in the ventricles you have this chaotic erratic signaling which looks like coarse squiggly lines on EKG the ventricles are just spasming now what are the big risk factors of v-fib well I like to separate the major risk factors in the two categories the first one being anything that causes general irritability to the matricula cells now irritable ventricular cell means that it's likely to just over fire or fire abnormally the other risk factors for v-fib is anything that causes scar tissue formation now let's go back to the irritable ventricular cells what would cause ventricular cells to be irritated well the most classic example is coronary artery disease coronary arteries are the blood vessels that supply the heart with oxygenated blood and over time these blood vessels can get clogged and this might be because of years of smoking or bad diet over time these vessels get clogged when the coronary arteries get clogged you've got less blood flow to the ventricular cells these cells get less oxygen than they're used to having so they become irritated and they're more likely to over fire or fire abnormally also certain electrolyte abnormalities like high potassium or low calcium or low magnesium might cause ventricular cells become irritable and why is that well electrolytes play an important role of normal electrical conduction in the heart and you can imagine if the electrolytes don't have the right levels this could disrupt normal electric conduction through the heart okay and now for scar tissue so we said scar tissue can also set up the heart for ventricular fibrillation so what might cause scar tissue well the most classic example is a heart attack like we said we have coronary arteries that supply the heart with oxygenated blood when you have a heart attack there's a coronary artery that gets clogged totally so no blood is getting to this part of the heart so whereas in coronary artery disease you had less blood flow and heart attack you have no blood flow to this part of the heart and this tissue ends up dying and it's replaced by protein kind of like a scab and it creates a scar tissue now scar tissue doesn't function like regular heart tissue it's not going to conduct signal like regular heart tissue would instead it sets up for abnormal firing or neural abnormal circuits in the heart and this disruption an electrical induction can set up the heart for particular fibrillation other things that can lead to scar tissue formation is a cardiomyopathy so cardiomyopathy just means disease of heart tissue in which the heart tissue doesn't function as well so it loses function it doesn't lose all function but it doesn't function as well as a normal heart would cardiomyopathies have a lot of causes so infection can be a cause so there are some viruses that affect the heart and make the heart tissue actually a decrease function there are certain genetic disorders that can cause a cardiomyopathy and these disorders will actually change the structure of the tissue of the heart making them lose function and also years of coronary artery disease which I'm going to write as CA d so years of coronary artery disease where the heart is constantly getting less oxygen than it optimally wants over years eventually that heart tissue is going to lose function again all of these things my cardiomyopathies predispose the heart to have scar formation and scar disrupts normal electrical conduction I can set the heart up for v-fib and one final thing that might cause particularly fibrillation that's not as common is electrocution an electrocution you have some sort of outside source of electricity entering the body so where the heart would have a normal electric induction system electrocution is going to disrupt this normal signaling and that can lead to particular fibrillation