all right so for today's video we have another cardiology collaboration and we're going to be talking about a common cardiac complication of surgery in atrial fibrillation right so we're going to go ahead and jump right in uh so to sort of outline today's talk we're going to talk about what atrial fibrillation is in general some common post-operative causes of atrial fibrillation the fundamentals and general principles of of working it up and managing it and sort of ultimately our goals of treatment uh so from a surgeon's perspective why why do you care about atrial fibrillation yeah i think afib is a really important topic for us to talk about because it's actually rather common depending on the type of surgery particularly thoracic cardiac or vascular surgery there are actually quite high rates of afib but even with any postoperative patient especially as our patients get more and more elderly it's a complication we're all going to see and should be comfortable initially working up that's especially important because this is often not just a cardiac problem but a problem that is a harbinger of some other post-operative complications that we need to be able to manage ourselves as surgeons yeah exactly i think that's a great way to introduce what it is and what atrial fibrillation is in general so as you guys remember and know wells so in terms of the normal pumping chamber of the heart the atria or the top chambers of the heart pump fill the ventricles and then the ventricles sequentially pump blood either to the lungs or the systemic circulation in atrial fibrillation which is the most common uh heart arrhythmia affecting up to one in a hundred of the population the atria top chambers of the heart beat or quiver or shake or fibrillate abnormally usually at a rate of about 400 to 600 beats per minute and in terms of the path of physiology i want you to think of really anything that causes increasing pressure in the left atrium sort of dilates the left atrium and and can predispose patients to getting atrial fibrillation so the most common thing we see are age and then a stiff or thick heart um so left ventricular hypertrophy which can be related to obesity high blood pressure sleep apnea among other things and then generally in the post-operative state we see some degree of high circulating catecholamines and these sort of factors play together in the development of postoperative afib so this is a pretty simple straightforward ecg in terms of a patient who would be coming in with atrial fibrillation with rbr or someone you would see postoperatively the key factors that i always want you to remember obviously the rate is tachycardic that's one key you don't see any clear p waves what you're seeing here periodically these are just fibrillatory waves you can see that the r waves uh here to here for example versus here to here is completely irregular the sort of patho mnemonic finding in atrial fibrillation is an irregularly irregular rhythm and that's what we see here so if you see someone no clear p waves irregularly irregular and tachycardic those are the defining features for atrial fibrillation so in terms of potential causes in a in a post-operative patient i want you to think of a high catecholamine surge being the cause of atrial fibrillation until proven otherwise and in a post-operative patient that can be anything from infection and that can be wound infection intra-abdominal infection pneumonia etc um bleeding particularly from the surgical site or related to the surgical site um hypoxia and hypercarbia that could either be from something like a new pe or if they have sleep apnea and they haven't been on their cpap or they're still waking up from anesthesia um and are and are still sedated for example volume status in general so that can be either hypovolemia related to under-resuscitation or fluid overload if they're a patient that has long-standing heart failure they got too much volume in surgery electrolyte abnormalities particularly hypokalemia and hypomagnesemia are the important ones to know and then i'll add in here as a caveat thyroid disease usually people know about underlying hyperthyroidism but it's something important to check and then um substance withdrawal is always something important to think about um you know we always hope our patients tell the truth but alcohol withdrawal frequently so if you see someone who has a history of drinking and is presenting with afib with rbr usually post update two or so this is another another important thing to think about and then in terms of underlying heart disease can you think of some underlying heart conditions that could predispose someone to having atrial fibrillation sure um i think like you're saying it's interesting that we've talked about all these potential causes for afib and we haven't talked about underlying heart disease yet i think that really brings home the point that if the only thing that's changed in a patient's status is that they've had surgery whereas previously they hadn't and now they have a new onset of afib that probably there's something going on related to the surgery that we as surgeons need to be really acutely working up and managing when it comes to heart disease just about any heart disease can predispose you to afib as my understanding like you said it's the most common arrhythmia some things that we can do wrong that would lead to afib would be things like withholding medications generally patients should be on their beta blocker in the period period but if it's held maybe for some hypotension uh that could be an issue um or if they have chf or valvular abnormalities yeah perfect i think you hit pretty much all of them so and and the other point that he made that i want to reemphasize and if there's one thing you get and keep from this talk it's that most likely it's not something new from the heart it's usually someone who has the risk factors we talk about may or may not have pre-existing heart disease and that can be valve disease heart failure or known history of afib previously but it's usually some sort of stressor in the in the new post-operative period that is contributing to their atrial fibrillation with rbr i also want to mention and point out i frequently get asked the question is it possible that they're having a myocardial infarction or heart attack it is possible but rarely we see very very rarely we see atrial fibrillation as the only presentation of of an mi it's usually accompanied by symptoms and other ekg changes besides just atrial fibrillation so this will be a common page for any of you who are working as sub-interns or as interns in probably the upcoming couple of years so if you were to get this page about a patient mr smith uh he's post-operative day one um and his heart rate is 145 please assess kind of talk to me through talk me through what your thinking is and and what your plan is after you get this page yeah so i see this page and i'm assuming that this is an acute finding that's why they're paging me about it so i'm fairly concerned anytime i get a page where there are significant vital sign abnormalities that gets top priority so i'm going to be calling this nurse back as soon as possible and asking her a little bit about the patient and while i'm talking them on the phone i'll be putting in some orders for some key uh studies so usually what i'm going to ask them right away is are there any other vital signs abnormalities most most concerning or i'm most concerned about hypotension with this tachycardia or altered mental status i just want to kind of get a picture of what's going on quick while i'm ordering for example my ekg and likely some labs and then i'm going to be going to see that patient as soon as possible great perfect so i think you totally hit it on the head i think and the the first thing you should think about in this patient are there the rest of their vital signs you notice in the page they only gave you the heart rate but definitely want to know what their blood pressure is and what their respiratory rate and o2 sat etc um when you're kind of on your way over there you may have ordered some of the things that you mentioned including an ekg and some labs that we'll talk about and then talking to the patient and getting a sense of if they have any symptoms and doing a physical exam will be important when you get to the room as well what sort of labs are you thinking about ordering on these patients yeah so like you talked about when you were talking about the causes of a catecholamine surge i'm trying to rule out most of those things i'm getting a pretty broad lab panel certainly a cpc which would talk to me about infection or anemia i'm thinking about getting a bmp plus a magnesium to look for any critical electrolyte abnormalities an mi is rare but we certainly don't want to miss it so i'm going to get a troponin and be trending those and then in the acute setting i'm not as worried about it but like you said you can work up thyroid studies a couple of those rare labs oh and depending on what the nurse is telling me on the phone i might add on a blood gas and a lactate perfect i think you hit most of the big ones that we want to think about and then some other studies you may think about are imaging studies and that's mostly related to after you've seen the patient and examined them if you're concerned about some of the other causes we talked about for example if someone has just had an abdominal surgery and you're you know concerned that they're hypotensive or their drain output is picked up and looks bloody if you're thinking about getting a ct to assess the abdomen or if they're hypoxic newly and you're concerned about a pe those are there's not specific imaging studies that you order in the acute setting but that's sort of patient and case dependent and then you may get a cardiology consult in some of these cases generally we'll we'll talk about that a little bit later in terms of when would be appropriate to get cardiology involved versus sort of initial management so in terms of uh management of the patient so we'd ordered an ekg and some some lab tests and you'd sort of alluded to asking about the rest of the vital signs what what other things are going on in your head about the patient when you're walking over to assess them in person yeah so the first thing uh kind of the most versatile and quick tool that you have is just talking to and looking at the patient so i'm going to be taking my history from them and the first thing is can i take a history from them or not if they're altered newly that's a huge concern obviously about their cerebral perfusion but if i am able to talk to them that reassures me a little bit that uh whatever they're doing right now is at least able to perfuse their brain and keep alive their basic bodily functions once i'm talking to them i'm also going to be looking at the monitor looking at the blood pressure and really deciding is this stable or unstable afib because that's going to change my very acute management in that moment regardless of the underlying cause perfect exactly so when you're talking to a patient exactly the the first time you see any patient with any sort of tacky arrhythmia particularly afib stable versus unstable is always the first thing you should think about if they're unstable you go down the acls pathway which we'll talk about briefly if they're stable you want to do a sort of limited focus history and physical you want to really ask if they're having symptoms and the symptoms you're most concerned about are chest pain shortness of breath or some of the most common lightheadedness or dizziness and then altered mental status like you mentioned and that you know they're not going to describe if they're altered but asking key history and orientation questions will help you get a sense of of how their mental status is doing and then on physical exam you want to auscultate for abnormal rhythm and rate which you'll get a sense of ideally these patients should be put on telemetry as well which will also give you a sense of what their rhythm is and then trying to get a sense of their volume status will be helpful so listening to their lung fields to see if you hear crackles if you can assess their jugular venous pressure in their neck and for evidence of lower extremity edema or swelling those will be key findings that can suggest someone has evidence of extra volume on board versus someone who is sort of you know warm vasodilated bounding pulses etc that may be someone who's infected so there are certain very key physical findings that will be helpful in elucidating the causes of what may be going on in this patient so in general our goals of treating these patients like you mentioned first stabilizing the patient so if they're unstable going down the more of the acls pathway to make sure they're stable and then figuring out the underlying cause and like i said i can't stress this enough because you can throw medications at them all you want to get there try to get their heart rate down or try to get them out of atrial fibrillation but at the end of the day if you haven't corrected the underlying cause they will still be constantly predisposed to going back into atrial fibrillation once you've identified an underlying cause and are working to address that you can also think about rate controlling them and liberally rate controlling them not sort of trying to drive their heart rate down as low as possible so in terms of managing patients um in terms of an unstable patient what would be the first thing you do for an unstable patient with afib with rbr i was really hoping you wouldn't ask me the acls algorithm but it looks like here we are so the first thing that you're thinking with unstable afib is about electricity so getting the pads available getting them on the patient and then uh i'm thinking about cardioverting if i'm unstable if i'm unable to get them stabilized otherwise yeah exactly so in an unstable patient and you know we always think of patients who are hypotensive and are showing signs of hypoperfusion and altered mental status and inappropriately low urine output are sort of the really quick bedside uh markers you can use for assessment i'm thinking about using electricity or performing a direct current cardioversion on these patients exactly like you said and then what about in a more stable patient what medications are you thinking about using yes in a stable patient i really see myself as having three choices really two big ones at the beginning if their blood pressure is very clearly uh will tolerate it usually i'm first trying beta blockers usually metoprolol uh if they're but if their blood pressure is a little bit on the lower side i might be thinking of uh something more like ambioterrain and then the third option is the centrally acting calcium channel blockers most typically guilty zone great exactly so i would say your generally your first line medication is exactly right metoprolol in terms of iv beta blockade that'll give you the biggest bang for your buck it generally doesn't affect your blood pressure a whole lot um usually we give it in stacked doses so we give five milligrams five minutes apart for up to three doses and this may be a little bit different depending on your institution but this is generally uh recommended as as your first line um in terms of centrally acting calcium channel blockers diltiazem is used a little bit more frequently than verapamil deltazem is generally less potent in terms of causing low blood pressure and you can use it as a continuous infusion which makes it a nice choice to transition to if a patient can't take pills for example and then amiodarone as you mentioned in p people who have underlying heart failure or really low blood pressure and you don't think you can get away with using a beta blocker or calcium channel blocker is always a good option i want to just mention digoxin because you may have heard of it being used for atrial fibrillation rate control digoxin generally tends not to work as well in high sympathetic tones or high catechol menergic excess so digoxin is less commonly used in the post-operative setting and then as we mentioned before cardioversion in someone who's truly unstable and you're thinking about acls you mentioned um something about different meds being good or not good for people with heart failure can you expand on that a little bit how do you decide who's in heart failure and which meds are good or bad yeah exactly so generally if someone's had a prior echo within the past six months or so i generally look at that ejection fraction usually if their ejection fraction is above 50 or so on that echo i would say you're safe to use essentially all of these medications if their ejection fraction is less than 50 i would avoid calcium channel blockers these have a really potent negative inotropic and chronotropic response and they can cause really profound hypotension in someone with a reduced ejection fraction and we didn't mention this you know usually in the acute setting like we talked about you want to stabilize the patient um and then kind of work on figuring out why they're an afib and then use medications usually sometime during their hospital stay like i mentioned if they haven't had an echo in the past six months or so you're usually not urgently getting an echo to assess what their lv function is and left atrial chamber size etc to just have that as a baseline yeah so a lot of details on this slide don't feel like you need to know all of them especially if you're a medical student but hopefully it's good for you if you're curious if you want to know a little bit more but really just focus on are they stable or not if they're unstable what do i do if they're stable what are my big classes of meds and you'll be able to follow along in the hospital a lot better and then just a quick point about longer term management something that everyone should know about is patients who have any history of atrial fibrillation are at increased risk of stroke and even that can be even people who have sort of self-limited shorter term episodes of afib so this is not necessarily something that you have to think about right in the acute setting but something that should be thought about closer to discharge in patients is anticoagulation and i won't go into it too much but it's helpful to be familiar with two scores you may hear them you don't need to memorize them but you'll look really smart if you if someone's talking about bleeding risk um or should we put this patient on anticoagulation there's two major scores the chad's vast score helps us sort of risk stratify patients in terms of what their estimated annual stroke risk is with certain risk factors for the development of afib and then the has blood score is their bleeding risk and we usually take these scores into account when we're deciding when to put someone on long-term anticoagulation again it's not important that you memorize this it's it's just good to know because these are referenced quite frequently and this is what we use to help us determine the safety of anticoagulation obviously in conjunction with talking to the patient and their family so that's all i have i i hope you learned a little bit about atrial fibrillation in terms of the basics and management and are a little bit more familiar with it the next time you will inevitably see a patient with post-operative atrial fibrillation in the hospital awesome thank you so much as always i've learned something i'm sure people watching will learn something as well it's a big topic we just scratched the surface here um so if you have follow-up questions we're always happy to answer those in the comments or maybe with future videos we hope you enjoy remember this video is for educational purposes only do not use this to diagnose or treat any diseases and we'll see you next time