Cardiovascular System 8, Normal and abnormal heart rhythms

now here we're looking at an ordinary sinus rhythm and it's called a sinus rhythm because it's generated in the sinoatrial node in the heart in the right atrium herma notice here that this monitor will count for us so the rate is currently 71 beats per minute and that's quite normal a normal sinus rhythm now there's actually only three normal heart rhythms and there were variations on this normal sinus rhythm we call this a sinus rhythm because it's got a p q r s t waves and the pqrst waves are in the right order and the rhythm is fairly regular and it's a sinus rhythm because the rate is between 60 and 100 beats per minute so if we wire you up to our electrocardiograph machine this is what we would expect to see a normal sinus rhythm now this patient's heart rate is slowing down and in fact the machine's not very happy about it so it's alarming so I'm just going to pause the alarm because it's warning others something's wrong what these potentially wrong now there's a pqrst in the right order and it's fairly regular but we can see now that the heart rate has dropped down to 37 and it's flashing because it tells us this is an unusual situation so a sinus bradycardia brandy means slope it's still a sinus rhythm because it's generated in the atrioventricular node as we can see by the normal pqrst complex but the rates is less than 60 so brandy cardian has a rate less than less than 60 so it's a sinus rhythm if it's 60 to 100 it's a bradycardia if it's less than 60 now there's a lot of causes for this if you're fairly fit you might have a bradycardia to have a low resting heart rate is good some super athletes can have a heart rate of listen to be perfectly normal for them if they're athletically fit and we often see the heart rate go down when people are asleep and very often we notice it when people take beta blockers but of course there's also pathological causes for example this could be part of a vasovagal episode or it could be a consequence of hyperthyroidism where the metabolism is low now the key thing here is to check the pulse and the blood pressure to see if the patient is symptomatic because some people can maintain a perfectly good blood pressure with this and they will be perfusing their tissues whereas other people will be desperately ill so they're symptomatic with this they could be dizzy lightheaded even syncope falling over feeling faint losing consciousness they could be short of breath if they're active they'll tire quickly with physical activity as well if it's severe there can be altered Mental Status and confusion and some people especially if they've got ischemic arteries can have chest pain as the car as the myocardium could be hypo profused if is not generating adequate blood pressure so always taking blood pressure always for your the pulse if the patient's not maintaining a blood pressure if there's a cerebral hypoperfusion not enough blood pressure go to their brains then we would like them head down to get the blood circulation going down to their brain and of course would treat the underlying cause and sometimes we can treat this symptomatically by giving at repair which is an anticholinergic so it's a parasympathetic blocker and will block the activity of the parasympathetic nervous system because it's the parasympathetic nervous system that slows the heart rate down and it's the sympathetic nervous system that speeds the heart rate up now here we notice the machines alarming again because it doesn't like this rhythm is far too fast and we can actually see on the monitor the counsel for us this patient is now very tachycardic they have a fast heart rate so a tachycardia has got a pqrst and I think you can see there's a PQRS and a T on this is all just a bit concertina together it's all a bit close together because it's running fast so a sinus tachycardia pqrst right ward a fairly regular but the rate is over a hundred now as many causes for this but basically the heart rate is increased by sympathetic autonomic nervous system innovation and this is normal of course in emergencies exercise or excitement the so called three e's and patients can have an increased heart rate when they come into hospital purely because of the anxiety but it's good in some circumstances that the heart rate can increase because this can increase cardiac output to say it's a compensatory activity remember cardiac output is the amount of blood pumped out by the Harper a minute and cardiac output is the heart rate multiplied by the stroke volume the volume the heart is pumping out per contraction so one way for the body to increase cardiac output is to increase the heart rate in a compensator tachycardia and this is what we get for example of a patient's hypovolemic if they have low volume of blood after hemorrhage or after diarrhea vomiting or after burns for example and here the pulse often feels fast weak and thready but we can also see this in anemia hypoxia hyperthyroidism where the metabolism of the body is too fast we can see this in compensated heart failure myocardial dysfunction such as ischemic heart disease myocarditis see in many conditions the symptoms of this depend on the cause there very often eight there may not be any anticipation was hypovolemic for example and not maintaining a blood pressure when they might be dizzy and the treatment is to treat the underlying cause of the condition now if you want to lower your heart rate which is good physiologically speaking then we need to get fitter because fitter people tend to have a little heart rate so we can exercise more lose weight manage stress avoid alcohol and of course don't smoke but I'm not sure you needed me to tell you that so they're the only three normal heart rhythms sinus rhythm between sixty and a hundred sinus bradycardia less than sixty sinus tachycardia greater than 100 and of course this sinus tachycardia would be perfectly normal if you are running for example it depends on the situation and has to be interpreted as to whether it's a physiological tachycardia or a symptomatic of some underlying pathophysiological derangement so the rhythm we're looking at now is atrial fibrillation the atrial myocardium is fibrillating but we can see this coordinated ventricular contraction in these qrs's so we can see the fibrillation now on the isoelectric line which is detecting the fibrillation of the atria but impulses are getting through the sinoatrial node causing contraction of the ventricles which we see but we notice that it's irregular this irregular in rate and it's a regular in strength of contraction so atrial fibrillation is sometimes called an irregular irregular rhythm it's irregularly irregular you can get a slower jf so this is a fairly slow one more commonly AF is a bit faster [Music] so this would be a faster atrial fibrillation now this is acute in onset we can actually treat this with machines alignment cuz it doesn't like the flus rate this is acute in also can actually treat this by Anitha ties in the patients and defibrillating them because there is fibrillation that has just the dis a tree or fibrillation and that can restore sinus rhythm if it's more long-standing we'll often and choose to treat with medication now at first glance this rhythm may appear normal as a pqrst in the right order but can you see the gap between the P and the QRS is prolonged and if that gap is more than five small squares which is naught point two seconds we will call that a first degree heart block this patients in a first degree heart block this patients in sinus rhythm at the moment let's just keep an eye on now patients now go into ventricular fibrillation and in ventricular fibrillation there's fast none of them as machines alarming to tell me that's good I have noticed so in ventricular fibrillation this fast chaotic uncoordinated contraction of areas of the myocardium different bits of the myocardium doing its own thing is twitching and quivering and in this rhythm there's no effective cardiac output the blood pressure is going to be zero now the causes of this can be ischemic heart disease such as myocardial infarction severe war congenital heart disease electrolyte imbalance rapid changes in the levels of potassium or calcium in the blood for example could be electrocution severe hypoxia and we notice the rhythm is irregular with poorly formed wide QRS complexes and I would certainly classify this as a course of ventricular fibrillation but because we're not treating it it will become finer over time we're going to find a variable ocean so now we can see it's becoming finer it's not as the amplitude is less than it was and the finer ventricular fibrillation is harder to treat so this is much finer now and the longer we don't treat this the finer will tend to become the finer it is the more difficult it is to respond to defibrillation this verse is quite a lot course and answer should respond to defibrillation more readily patients of course in ventricular fibrillation is going to be very rapidly unconscious no pulses agonal or no respirations as a first aid treatment we would have to give CPR but then the treatment for fibrillation is electrical defibrillation now this rhythm is a ventricular tachycardia vitia very rapid ventricular contraction but with the degree of coordination oh this is quite a severe ventricular tachycardia and this patient will probably be unconscious but in sort of ventricular tachycardias the patient can remain conscious for periods of time indeed hours although they'll feel very unwell and if we don't treat this condition this ventricular tachycardia it will become a ventricular fibrillation as the rhythm gets finer and we have to treat this with defibrillation it's one of the shockable rhythms so there's only two shot algorithms ventricular fibrillation and this one which is ventricular tachycardia if the patient's not unconscious we have to of course Anitha ties them prior to administering the shock now this patient is in a systolic cardiac arrest there is no systolic contraction at all event record and indeed the atria are not moving and asystole a means without of course this is the rhythm that you will get with anyone who was dead but if someone's gone into this with him recently we would try to try to reverse it by inducing a shockable rhythm such as ventricular fibrillation so that's a systolic cardiac arrest now there's another type of cardiac arrest called pulseless electrical activity and that's exactly what it says there is no pulse but there is still electrical activity going on in the heart and the waveform of that electrical activity can vary quite a bit but he could look something like this like almost like a normal in this case sinus bradycardia but the key thing is there was no kinetic movement of the heart so the depolarization of the ventricular and atrial myocardium is going on as normal but the heart muscle is unable to respond to that so we would need to try and correct the underlying causes of this and indeed that's true with any cardiac arrest we need to try and correct the underlying causes and this is where the five ages and the five T's come in as causes of cardiac arrest that we couldn't use to prevent cardiac arrest but we can also use it to try and reverse a patient who's in cardiac arrest and the five ages causes of cardiac arrest are hypoxia not enough oxygen getting to the myocardium hypovolemia not enough blood getting to the myocardium hypothermia when the body temperature is too low hypo or hyper Kaleem 'ya both can cause cardiac arrest whether the potassium is too low or too high and the fifth H is hydrogen ions which of course is the cause of acidosis so there's more hydrogen ions the pH will be lower because the patient will be more acidotic and then the five teasers causes a cardiac arrest one is tension pneumothorax where there's a buildup of pressure in the pleural space cardiac tamponade t4 tamponade where there's increasing pressure within the pericardial sac constricting the heart Tifa toxins and potential drugs of course and then t4 thrombosis which could be pulmonary thrombosis and t4 thrombosis would become the coronary thrombosis so this shows the importance of not just looking at the monitor but assessing the patient's overall condition and palpating central and as well as possibly peripheral pulses [Music]

Channel: Dr. John Campbell

Views: 255,035

Keywords: ECG, ekg, heart rhythms, dysrhythmias, ahythmias, cardiac arrest, sinus rhythm, af

Id: cSugcAq61S0

Length: 20min 17sec (1217 seconds)

Published: Thu Mar 14 2019