- NCLEX-RN questions on tachycardias 1
- NCLEX-RN questions on tachycardias 2
- Electrical conduction in heart cells
- Normal sinus rhythm on an EKG
- Supraventricular tachycardia (SVT)
- Atrial fibrillation (Afib)
- Atrial flutter (AFL)
- Multifocal atrial tachycardia (MAT)
- Atrioventricular reentrant tachycardia (AVRT) & AV nodal reentrant tachycardia (AVNRT)
- Ventricular tachycardia (Vtach)
- Torsades de pointes
- What is ventricle fibrillation (Vfib)?
- Pulseless electrical activity (PEA) and asystole
What is ventricle fibrillation (Vfib)?
Ventricular fibrillation (also referred to as VF or v-fib) is a fatal cardiac rhythm that occurs when the lower chambers of the heart (ventricles) lose the ability to contract and circulate blood to the rest of the body. V-fib results in an ineffective, erratic heartbeat as blood stops flowing through the body and essential organs experience a dangerous loss of blood supply. Individuals with v-fib typically lose consciousness very rapidly and will have no traceable pulse, so immediate medical assistance, including CPR and the use of a defibrillator, is crucial.. Created by Bianca Yoo.
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- what if someone with Vfib is struck by lightning. I have heard of lightning saving a few lives so I guess in someone with Vfib, that lightning would act like a defibrillator to make them have a normal ventricular heart beat(Though if they don't have Afib it might start Afib.).
Is this actually true that someone with Vfib can be saved by lightning? Is that what takes up the majority of the lightning strikes that don't lead to Vfib is the lightning acting like a defibrillator?(2 votes)
- Given that the odds of living for more than a few minutes with ventricular fibrillation are low and the odds of getting struck by lightning are low, I'd venture to say that no one has ever had their life saved from V-fib due to a lightning strike defibrillating them. The lightning does not always cause v-fib because it does not always pass through the heart in a way that leads to the abnormal rhythm and may bypass the heart altogether.(5 votes)
- what is the priority nursing intervention for a patient in V-fib?(1 vote)
- Maintain perfusion and ventilation, restore normal sinus rhythm.(3 votes)
- Is 'penumbra' the medical term for the area of dead tissue discussed at6:40?(2 votes)
- The penumbra is the area around the dead centre, it has an impaired blood supply, is already lightly damaged but still contains living cells which can die or recover.(2 votes)
- What if someone has signs of multiple tachycardias? Like both Afib and V tach for example?
How would you go about treating someone with multiple tachycardias?(1 vote)
- Beta blockers would treat both A-fib and V-fib.(2 votes)
- What are the specific genetic disorders that can put someone at risk for V-Fib?(1 vote)
- when the AV node doesnt work and the ventricles dont get the oxygen, does it not start ventricular escape beating?(1 vote)
- All of the cell types in the cardiac conducting system have their own rate at which they'll sponteneously depolarise. These rates get slower the further through the conducting system (from 60-100 at the SA node down to 20-40 in the ventricles). This innate pacing happens any time there isn't a faster signal from higher up, regardless of oxygenation. This can be seen in conditions like a complete heart block.
Where cardiac muscle doesn't get oxygen, ATP dependent processes like cell repolarisation can't happen. Loss of oxygen supply to cardiac muscle means that the cells stop working properly, and over time will start to die.(1 vote)
- 2:56Will a patient still be able to speak during V-fib?(1 vote)
- No. A patient in VF doesn't have enough cardiac output to maintain consciousness, so they won't be able to speak.(1 vote)
- what if the guy is awake but in Vfib?(1 vote)
- [Voiceover] 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 lose 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 vessels, 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, sinoatrial, SA node. The signal travels from the SA node down to another structured called the atrioventricular or AV node. So, that stands for atrioventricular or AV node. From the AV node, the signal goes down to the ventricles and signals to the ventricles and makes the 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 longer 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 walls 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 to 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 coordinated 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 and 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 forward movement of blood to the vessels, you're not going to have a pulse. Sometimes, right before someone collapses from ventricular fibrillation, they might complain of 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 since 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 when you're not circulating oxygen through the body. An EKG in someone in V-fib looks like this. You're going to see course squiggly lines. This is because you lose this 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 course 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 into two categories. The first one being anything that causes general irritability to the ventricular cells. Now, an 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, but over time these vessels get clogged. When the coronary arteries are 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 to become irritable. And why is that? Well, electrolytes play an important role of normal electric 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 is 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, in 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 this 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 abnormal circuits in the heart. And this disruption in electrical conduction can set up the heart for ventricular 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 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 CAD, 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 from the cardiomyopathies predispose the heart to have scar formation, and scar disrupts normal electrical conduction and can set the heart up for V-fib. And one final thing that might cause ventricular fibrillation that's not as common is electrocution. In electrocution, you have some sort of outside source of electricity entering the body. So, where the heart would have a normal electrical conduction system, electrocution is going to disrupt this normal signaling, and that can lead to ventricular fibrillation.