Arrhythmia Control – Cardiovascular Pharmacology

00:01 Let’s talk for a few minutes about arrhythmias.

00:05 This is a huge field, actually, a total specialty on to itself and in a few minutes here, I am not going to be able to do anything more than brush the surface, but I am going to talk about the most common arrhythmia which is atrial fibrillation. Mention… I mentioned it just previously, right? The heart, as you know, has electrical system as we have talked about which keeps it beating very regularly like this, the im-… electrical impulse starts, remember in the high right atrium, and passes through the atria and down into the ventricle causing a co-ordinated contraction. What happens though when that electrical activity is disturbed in the atria and instead of doing this, the atria do this? When that happens, of course, we get areas of low blood flow within the atria and as I have mentioned before, a clot can form and that clot can result in a stroke, if the clot gets outside the heart.

01:00 So, first of all, we have drugs actually for trying to control atrial fibrillation and keeping patients in sinus rhythm. There’s a whole variety of these drugs, but many of them are associated with very significant side effects. When I talked about Statins, remember I mentioned very few side effects. But, when I am talking now about anti-arrhythmic drugs, the number of side effects is quite severe and even some of the side effects can be fatal. So, these agents have to be used very carefully, just like the powerful anti-coagulants. You have to use them carefully. It requires a great deal of training to use these drugs effectively and also, to pick the right patient to get them. So… and remember what I also said, one of the other treatments in a patient with atrial fibrillation is to prevent the blood clots and prevent the stroke. So, sometimes, we will give drugs that hold the patients in sinus rhythm and sometimes, we can do an electrical procedure where we sort of… with a catheter burn out the area that’s setting off the atrial fibrillation. Often, that means you still have to take some anti-arrhythmic drugs and a blood thinner to prevent the blood clots.

02:14 So, the treatment of… of patients with atrial fibrillation often involves several drugs.

02:20 Both a drug to either control the heart rate and leave the patient in atrial fibrillation or control the atrial fibrillation and restore the patient to the regular sinus rhythm. And finally, there are agents to prevent the blood clots within the heart.

02:35 I just want to show you two examples, again. Here, you will recognize this as an electrocardiogram.

02:43 This is a normal electrocardiogram. I am not going to spend any more time going over all the details of it other than to say, it shows the patient in nice regular rhythm.

02:53 And you can see that nice, regular rhythm, each heart beat which is the big upward and downward deflection comes at approximately the same time.

03:03 Compare this normal electrocardiogram with this electrocardiogram in atrial fibrillation.

03:11 Notice, here the spikes are completely irregular and the heart rate is very fast. It’s about 130. And that’s very common in atrial fibrillation. Patients recognize it because they say, “Oh my goodness! All of a sudden my heart is racing away with me.” And if you try and take the pulse, let’s do a little… sound experiment. In sinus rhythm, the pulse goes like this “boom, boom, boom, boom”. In atrial fibrillation, the pulse goes like this, “boom, booboom, boom, booboom, booboom, booboom, boom”. You can hear, it’s first of all, very fast and second of all, very irregular. If patients have underlying heart disease, you could imagine that this fast heart rate is not good. If the patient has narrowings in the coronary arteries, the fast heart rate can make the heart run away from its blood supply and cause angina and even cause heart attacks.

04:05 In patients who are in heart failure, it can make the heart failure much worse. They become much more short of breath and very frequently, these patients come to the emergency room for treatment. We will talk a little bit more about this when we talk in the section on arrhythmias later in ths series of lectures. In any case, it’s important for you to remember that atrial fibrillation is the commonest arrhythmia that we see. It becomes increasingly common with age and occurs in about 10% of people over the age of 80, both in Western Europe and in the Unites States. So, very, very common problem. There are other approaches, as I mentioned, besides drugs, to arrhythmia control. I mentioned that there is a catheter based technique in which one can actually burn out the focus in the atrium that’s setting off the atrial fibrillation. Still, the patients often have to take drugs after that, both anti-arrhythmic drugs and drugs to… drugs to prevent blood clots.

05:07 Sometimes pacemakers can… special pacemakers can be inserted that help to decrease the risk of these arrhythmias and most of these things are going to be combined with drugs in order to control the arrhythmias. In many patients, the arrhythmias are fairly easy to control with a modest number of drugs. In other patients, they can be very difficult and there are multiple ablations, which is the electrical destruction of the arrhythmia that starts, multiple drugs used, these patients can be very, very challenging. Fortunately, they are the minority. In summary then, there are a variety of drugs that have been developed for the treatment of cardiovascular disease. Some of these drugs are used preventively. In other words, to prevent patients who are at high risk from developing heart attacks and strokes and the same drugs can also be used once the disease becomes manifest in preventing a second episode of heart attack or stroke. And of course, we are always looking for new agents to further improve our ability to care for this very common disease. Thank you very much. I look forward to being with you for the next presentation.