Chronic Refractory Angina

Stress and angina

Links: author: Clinical version

Contents

The nature of angina
The role of stress in angina
How could nature have got it so wrong?
How can we use this to control angina?
Beliefs about angina
The difference between heart attacks and angina
Relaxation techniques

The nature of angina

Angina pain is not the same as pain from the skin or joints and it does not obey the same rules. A simple thought experiment can be used to illustrate this by asking the patient to imagine walking out of the office with a small smooth stone in one shoe and a sharp piece of gravel in the other. Nearly invariably the patient will say that they would be aware of the stones immediately and would know which stone was in which shoe. And yet whoever died of having a stone in their shoe? Compare that to their initial experience with coronary heart disease and its' commonest manifestation, angina. Patients readily acknowledge that they have difficulty describing the pain and that it took a period of time before the diagnosis was made even after they sought medical advice. It is very rare indeed to meet a patient (including doctors) who "knew" what angina was straight away and then did the right thing i.e. take an aspirin and seek medical advice. That is because the heart does not have "specialised pain nerves" like the skin and the brain had no prior experience of myocardial ischaemia and had to learn what the signals meant before deciding on a course of action. The body had to "construct" the angina nerve before the brain could receive the signal and it uses the existing nervous system. Like a computer hacker the angina pathway hacks into the built-in pain pathways for the chest, the arm or jaw so it is hardly the brain's fault that it makes a mistake in localising the source of the trouble. Unfortunately once created the "angina" pathway develops amplification units along its course so that over time even a tiny stimulus can be amplified to provoke severe pain. As discussed below the brain only has one way of dealing with this new and confusing set of signals and that is to release adrenaline on the evolutionarily sound assumption that it is better to be safe (i.e. being prepared for an attack) than sorry (i.e. relaxing and not releasing adrenaline). Unfortunately for angina sufferers this turns out to be a major error.

The role of stress in angina

Stress can often provoke an episode of angina and  nearly all patients have experienced this. Many patients have already learned to avoid things that bring on stress which can can be brought on by anxiety, fear, anger, frustration. The problem with stress is that the body only has one way to deal with it and that is to prepare itself to fight or run away.  It works like this. The brain receives signals that makes it think that it is under threat. It releases chemical messangers called catecholamines such as adrenaline that cause the heart to pump more blood and signals to the muscles and blood vessels to prepare to do more work.  The flight or flight response has evolved over millions of years and can be very helpful in certain circumstances, for example when you are under attack. Unfortunately the brain can be fooled into thinking that it is under threat during an angina attack. The fight or flight response then makes angina worse. Nearly all angina sufferers have experienced an attack that gets worse and worse and eventually fear or even panic sets in. This is especially likely to happen during a heart attack when a blood clot forms on the inner lining of one of the arteries to the heart. Anyone who has seen or experienced a severe angina attack or a heart attack will remember how frightening it was. The fear and sweating that accompany severe pain are tell tale signs that lots of adrenaline have been released. Unfortunately releasing adrenaline during angina is like throwing petrol onto a fire.

How could nature have got it so wrong?

Nature is full of mistakes.  In fact our very existence is based on an evolutionary process and evolution works by trial and error. Every one of us carries a set of blueprints in our cells that we use to make the building blocks of our bodies. The blueprints are called genes and we pass them down from generation to generation. The key to evolution is that every now and again  mistakes happen so that instead of passing onto an offspring a section of the blueprint reading "make a thin coat of fur" a typo error produces the order "make a thick coat of fur". Whether a particular mistake out to be a good thing or not depends on the conditions at the time. For example the hairy offspring will be much better off than its hairless cousins if they have to go through a series of cold winters. They will be able to get out to forage for food and will keep fitter.  Come springtime and the mating season the healthy hairy animals will be more likely to find mates and pass on their genes containing the order to "make a thick coat of fur" and so the number of hairy animals will grow at the expense of the hairless ones. The ability to mate and pass on genes to the next generation is called biological survival and genes that enhance biological survival replace those that do not.  The point is that there is no planning involved it is simply a matter of being the right gene at the right time. The gene for making specialised pain nerves evolved because it helped the biological survival of the animals born with that gene so they were able to pass it on to successive generations. Further errors down the line produce modifications and the ones that best enhance biological survival in that generation replaces the earlier version. In complex animals like humans specialist functions take millions of years to evolve. 
In the 19th century doctors could not decide whether angina was a disease of the nerves or whether it was simply a symptom of heart disease. Early in the 19th century whilst (Darwinian) evolutionary theory was still being being seriously challenged a group of "experts" decided that angina was a natural warning mechanism. Since that time until today most people believe that this is the case. The trouble is that angina wasn't around millions of years ago when the nervous system was evolving.  Furthermore even if angina and coronary heart disease had been around there can be no biological survival advantage in a system that makes the problem worse by doing the opposite of what is required. How long would a company who produces smoke alarms which spray  petrol stay in business?  The only way it could stay in business would be if the alarm were so efficient in recognising a fire that help could come quickly enough to put out the fire despite that fact that the alarm had made the fire worse. Does this happen with angina? The answer is sadly no despite all the advantages of modern medicine. In fact nearly one fifth of patients die immediately, about a third of heart attacks happen without warning and the initial symptoms of angina are nearly always misinterpreted as something else such as  indigestion, rheumatism, toothache. Importantly when researchers have cut the nerves from the heart to the brain preventing the flight and fight response heart attacks are smaller.  The most likely explanation for angina is that it is a mistake. The nerve pathway evolved because it was helpful and the flight and flight response evolved because it was helpful. But put them together and they are a disaster for people with angina.

How can we use this to control angina? 

If stress can make angina worse then reducing stress can improve angina. There are a number of techniques to reduce stress. First it is important to be clear about what angina is. It is a mistake. You are not "supposed" to feel it. What you now know is that as soon as you feel angina the body is already releasing adrenaline that will probably make it worse. You can control this by convincing the brain that it is not under attack after all. The way the system works is this. There is a relay switch deep in the brain that is responsible for arousal. It receives incoming signals from the body and screens out unimportant signals. If it receives important signals it reflexively sends back the flight or flight order and wakes up the thinking part of the brain so that it can decide what to do. In other words the deep brain says to the thinking brain "We are in trouble. I have got the heart and muscles ready. What do we do? Fight or run?" Well you can't fight or run away from angina so the brain can't help. Even worse it panics and sends back the message "We are in serious trouble. Release more adrenaline" Thus the vicious cycle begins. In order to break down the cycle it is necessary to stop the two parts of the brain talking to one another.

Beliefs about angina

The 'thinking' brain is completely reliant on previous experiences which it uses to determine the meaning of  the information it receives. The "once bitten twice shy" phenomenon is almost certainly a built in protective adaptation to prevent us from making the same mistake twice. The more horrible the experience the more likely you are to remember it. Everyone who has had food poisoning will have certain triggers that remind them of the episode and these triggers might even make them relive the experience. These triggers might well have nothing to do with the food itself but could be the place where it happened. People tend to get over it in time but it can take decades. Heart attacks and severe episodes of angina are very unpleasant experiences and it is easy to see how minor episodes of angina can trigger the memory provoking the feelings of anxiety and the adrenaline release that accompanied the original attack. Doctors can sometimes make things worse by saying things like "you were lucky this time it was only a warning shot" or worse "you are sitting on a time bomb". Many people mistakenly believe that severe angina is a mini-heart attack and that their heart is gradually wearing out.

The difference between heart attacks and angina

Many patients misunderstand the difference between heart attacks and angina. Both are associated with pain which is often similar although usually worse in heart attacks.  That is because the same nerves are used and the brain receives the same information, just more or less of it. The difference lies in what causes the signals to be sent from the heart.  Heart attacks happen when a small tear occurs in the lining of the arteries that supply the heart muscle with nourishment. Complete starvation causes some of the muscle cells to die and at the same time triggers the heart nerves to send a signal to the brain which is felt as pain.  Angina is quite different. It occurs when there is enough nourishment to keep the muscles alive but not quite enough to stop it sending the nerve signal to the brain. Even more importantly the chemical signals produced in an angina attack stimulate nearby blood vessels to sprout a new blood supply. In this way the heart is able to produce its own bypasses. Many angina sufferers wrongly believe that each episode of angina is like a "mini heart attack" and that their heart is gradually wearing out. This is completely wrong and makes the patient even more anxious and stressed which in turn makes the angina worse. It is more accurate to think of angina as a cloud with a silver lining. Of course angina hurts and is unpleasant but  it means that the heart has grown a little stronger and less liable to a heart attack. The reason that the pain continues to be severe despite the improved blood supply is that the angina nerve is a highly efficient signal amplifier. The more often the nerve is activated the more sensitive it becomes and the better it is at ampliflying the signals until a few molecules released by the heart are amplified until millions of molecules arrive in the brain causing severe pain. Most patients have experienced the situation when a severe episode of angina is not accompanied by ECG changes and usually found that perplexing. This can now be explained by the fact that the ECG cannot register minute amounts of ischaemia but the nerve can. Even worse the fight or flight response feeds back to the heart and invariably makes the problem worse. By simply explaining this fact many patients are able to overcome their stress/anxiety response to angina and are more able to move onto the next stage of controlling their angina.

Relaxation techniques

The deep brain arousal centre can be tricked into thinking that it is not under attack after all and will stop sending out adrenaline to the body and will stop sending requests to the thinking brain. The way to do this is to breath very slowly (three seconds in then pause then five seconds out) and to relax the muscles of the body. The arousal centre now receives conflicting messages from the body. "I thought I was under attack but my muscles are relaxed and my breathing slow. Perhaps I was wrong.  I'll stop releasing adrenaline and check with the brain". If the thinking brain is saying to itself "Oh there goes the angina, just slow down for a bit and don't forget that it means that there will be a new blood vessel sprouting" it is easy to see that the vicious cycle can be broken. This approach can be coupled with other techniques (e.g. soothing music, relaxing images) and  is highly effective in reducing the severity of  attacks of angina. The patients who have mastered the skill of relaxation have acquired the skill over a period of time often with the help of experts (psychologists). As general rule it is easier to learn by relaxing different muscle groups at the end of breathing out whilst not in pain. If you would like specific relaxation advice and tapes return here in July 2000.

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All pages copyright © angina.org. Most recent revision: August 15 2002