so in anatomy we tend to talk about what normal is so of course a normal rhythm of our heart is normal it's what we expect so these are examples of cardiac arrhythmias which is basically when something's going wrong so we're not able to get that impulse to the rest of the heart not everybody's working on the same team at the same time so to review the p-wave is showing us atrial depolarization the QRS is showing aspen tricular depolarization and then the T wave is showing us ventricular repolarization so depolarization is sodium rushing in repolarization is potassium rushing in no more sodium rushing in so basically we start at a negative state we become more positive when we're depolarized and we come back to a negative when we repolarize stuff we had an A&P one so it's just important to know which is happening in which wave when we look at an EKG so this is a normal heart rhythm of course there's lots of things that can go wrong that's what this class is all about right so this is a list of the different things that can happen with the conduction system ectopic focus extra systole bradycardia tachycardia fibrillation and a heart block starting with the ectopic focus if you think of what an ectopic pregnancy is pregnancy has to happen in a uterus so when pregnancy when fertilization happens anywhere else an implantation happens anywhere else we call this pregnancy and ectopic pregnancy because implantation has to happen in uterus so the most common place for net topic pregnancy is in the fallopian tube and this is very dangerous it will never become a child it will never grow into anything but a tumor and it can be life-threatening for the mom so it's a very very dangerous thing so ectopic literally means kind of like outside where it's supposed to be so the SA node is there to set the pace right well sometimes something else takes over because it's just who's the winner chicken dinner so sometimes several of your heart cells will become hyper excitable enough to be the winner they're actually depolarizing faster at that moment and so they start setting the pace they start initiating the heartbeat the AV node happens a lot where the AV node takes over but it's a lot slower so as I said on the previous lecture it's enough to keep you alive because you're losing about 30% of the efficiency of your heart if you lose the atria squeeze the SA node is the one that's sending the signal to the ventricles so we really need this but this only affects your heart rate if the ectopic focus is faster than the SA node or the AV node it has to be the pacemaker it has to be the one that's the fastest so just because a part of your heart starts behaving wonky sometimes it's not enough to actually take over initiating heartbeat so if you look at this EKG it looks weird right it has that weird little pause this is what we call extra systole so this is where the SA node is doing its job but another site fires as well after it so it triggers two contractions this is not usually a big deal it looks terrible but really if we hooked you up to an EKG for 24 hours you'd probably have one of these exercise can cause this alcohol can cause this certain drugs but most of the time in a normal day you have an extra heartbeat so it's usually not a big deal same thing with bradycardia bradycardia is less than 60 beats per minute so 60 to 80 is considered normal less than 60 we would say you have bradycardia your heartbeat is a little bit slow but this can actually be a good thing a lot of you guys are all young and sprightly whereas I'm old so if you're really really young and you're in great shape which that ship has sailed for me you're probably gonna have a pretty slow heartbeat and that's good but it they're gonna do a lot of tests if you walk in there and you're like one of these people in this picture they're just gonna go oh bradycardia you're in good shape but otherwise it could be a sign of coronary disease that a not enough blood is getting to the heart it could be hypothyroidism your thyroid gland which we're gonna spend a lot of time on eventually is what kind of sets your metabolic rate so if you have hypothyroidism your overall body is going to be kind of slowed down it could also be you're getting too much potassium because potassium remember is there to relax the heart muscle well you could be getting so much potassium that you're relaxing to the point of not having a strong heartbeat tachycardia the opposite this is having over a hundred beats per minute so this is when your hearts abnormally fast so we've all had instances of tachycardia deer runs out in front of you guide chases you with the chainsaw you're gonna get some tachycardia right taking a test you get pretty stressed out you get some tachycardia but you could see where if you're running your engine it's kind of like your car if you're running your engine and it goes to shift and it kind of makes that urn sound if you're doing that to any machine if you're running a machine a lot harder and faster than it's used to running it can be damaging so we all experience this occasionally but if you're running tachycardia all the time it can be very hard on your heart I mean you're looking at a machine that has to last you hopefully a hundred years it's already beating a hundred beats per minute you don't want it to work or I'm sorry a hundred thousand times a day you don't want it to be at a hundred beats per minute as well so some causes nicotine those you that smoke know this my friends that smoke say it gives them a rush it gives them a buzz speeds up your heart adrenaline hopefully again a temporary thing caffeine I don't usually consume caffeine because I'm already like this all the time I'm already pretty wound up but occasionally I'll have soda or caffeinated tea I don't really like coffee but a lot of times I just don't like the feeling because it speeds up my heart rate because I'm just not used to it the naughty drugs drugs are bad don't do them but heroin crystal meth they give you that buzz potassium deficiency so if potassium is there to relax your heart having a deficiency not getting enough in your diet could cause your heart to overwork anxiety fear when you're really stressed heart rates gonna go up again on a test day right anemia so anemia we're going to talk about but it's basically you're not making enough red blood cells so your heart will speed up because it's trying to pump whatever cells you have it's trying to get that oxygen delivered to your tissues as quickly as possible so your heart rate speeds up and then hyperthyroidism like I said on the last slide your thyroid gland is there to set your metabolism so hypothyroidism is gonna slow your heart down hyperthyroidism is gonna speed it up you we also call have what's called fibrillation so this is asynchronous so you're not in sync nothing's working together rapid crazy heartbeat so the ventricle walls are twitching very very fast they're not working together so this is like an assembly line where every man's trying to do his own thing you're not gonna achieve anything so we're not gonna get enough force to actually squirt the blood out so things that can cause this a blocked coronary artery so this can be a sign of early heart attack problems the electric shock so we actually put you back into fib we put you back in by the defibrillator machine which is those little paddles there we use electricity put you back in rhythm injury to the to the chest wall if you hit your steering wheel in a car accident that's enough to sometimes throw your heart out of rhythm so we give you a shock to put you back in so this is showing you this is showing you a picture of ventricle then tricular fibrillation how crazy that heart rate is so obviously you can't sustain life for very long if your heart is not pumping blood efficiently so all of these sound pretty bad right but this one's definitely the worst out of the list this one's usually fatal so this is the one you usually can't fix or survive so this is a Navy block or heart block so causes cocaine drugs are bad ischemia which is cutting off blood flow to the heart so that would be a heart attack following that certain medications and certain birth defects some people are just born with problems with their conduction system so a Navy block they call it because you can't send the signal yet you can't get it through the AV node so something damaged the AV node again cocaine ischemia heart attack whatever so the problem is the a the SA node is there to cause the atria to squeeze the AV node is there to cause the ventricles to squeeze you can survive if your atria don't squeeze because most of the blood moves from the atria to the ventricles on its own but remember the ventricles especially that left side that that blood has places to go there are cells that are waiting on that stuff and so if you have damage to the AV node you're not gonna be able to squeeze your ventricles and if you can't squeeze your ventricles everything goes to hell so now no signal is coming down so all of the cells just kind of start doing their thing the atria the ventricles start start just contracting whenever call this dis arrhythmia and then at that point there's not enough blood especially in the left ventricle to squeeze out the aorta to keep your body alive