EECP – A Description

Background

EECP stands for External Enhanced Counter Pulsation – surely one of the least mellifluous terms in the medical dictionary. No wonder medics lapse into abbreviated jargon so easily – they would be candidates for throat surgery had they to repeat such terms more than once a day. So it is EECP to most people. This note explores some of the background from the layman’s viewpoint and is to help patients in understanding the treatment. The author does not have a medical background and so any mistakes are entirely my responsibility!

What is it?

In short EECP is a non-invasive method of modifying the flow of blood through the heart by applying external pressure through cuffs fitted around the legs. Quite a mouthful to think about but the basic principle is quite simple. If you apply a tourniquet to your arm or leg then very soon you suffer pins and needles because the external pressure has squeezed the arteries, limiting the blood flow to the area. EECP cuffs do the same thing but more gently, the squeeze being timed to modify the blood flow around the heart , rather than cut it off in the leg.

This is easiest to do when the main outlet valve from the heart (the aortic valve) is just closing. You can imagine the main (femoral) artery as part of a continuous column of blood between the leg and the interior of the heart, including the coronary arteries that supply blood and energy to the heart muscle itself. Any external pressure applied on the legs is therefore transmitted to the heart. The aortic valve opens and closes every heartbeat so, since it can’t be seen directly, the closing is detected by measuring the change in the electrical state of the heart. Electrodes are therefore taped to your chest, the output from which produces an ECG waveform, a procedure familiar to every heart patient. These signals are used to trigger a series of pneumatic valves controlling the air pressure in each cuff.

The equipment is in two main parts, firstly a couch fitted with 6 connections to the pressure cuffs - 3 for each leg, secondly a trolley containing an air compressor and control equipment with a console on top for the operator to monitor progress of the procedure. You sit on the couch and the cuffs are wrapped over your legs and buttocks and held in place using Velcro tabs. Each session lasts about an hour and, for best results, a course of 35 sessions is usually recommended. Effectively you are bounced around at your heart rate. If this is 60 beats a minute then you bounce gently on the couch once a second. It is possible to watch TV or read during the session but more intricate activities such as knitting are probably too difficult for most people

During the session the blood flow pattern is checked occasionally by monitoring the flow of blood in the finger using a device called a plethysmograph – a long name for a smart piece of kit. An infrared beam is shone through the finger and a detector monitors how much of the light is absorbed by haemoglobin, the red component of the blood; the greater the blood flow (or volume) the greater the absorption. The therapist uses the display of blood flow through each heart beat to tune the equipment for best results.

Why is it necessary?

EECP is usually recommended for people with heart disease of various types, lumped under the general term of cardiovascular disease (CVD). It is used in various parts of the world to treat other conditions also, but let us concentrate on heart disease. This means there is something wrong with the heart and/or its associated valves, blood vessels or nerves. Each individual patient is only too well aware of the drastic effects such disease can have on their quality of life. In physical terms the regular operation of the heart muscle and associated blood vessels is impeded, whether by fibrillation or blockage of the coronary arteries or malfunction of one or more valves. A common effect is angina, the pain experienced due to lack of oxygen supply to the heart muscle when trying to respond to the body’s demands. Stable angina can be very debilitating and lead to significant loss of quality of life; unstable angina, pain that varies rapidly, can be dangerous and should be reviewed by a medical professional as soon as possible after the onset.

Tremendous advances in medication and intervention procedures have been made over the last 30 years, advances which have corresponded unfortunately with a significant rise in the frequency of CVD in the population. Many heart patients would not be alive now without having benefited from these advances. Cardiologists are, however, not miracle men – they are not able to control and reverse all forms of CVD in every patient. While many patients have derived great benefit from procedures such as catheter ablation, coronary bypass operations or the fitting of arterial stents, there still remain a significant group (up to 15% of the total) who derive only limited or no benefit from such interventions.

EECP was devised as one way of helping this refractory group. One of its great attractions is that it is non-invasive – there is no need to carve holes in the body to gain access! Another great benefit is that it is remarkably safe – any side effects, eg skin chafing, are minor. The procedure has been a long time in development – over 30 years – and there has clearly been a long learning curve in design, test and introduction of the procedure to the cardiology community. The early work was done in China while more recent work has been done in the United States where it is now widely used as one of the battery of procedures available in the battle against CVD. Acceptance in Europe is much slower, partly explained by the different organisation of health care in each country and psychological factors - NIH (not invented here) !

EECP is not a universal panacea – some patients will have a combination of advanced symptoms that preclude any benefit; for instance EECP does not help with atrial fibrillation (AF). Large patient groups in the US have benefited from EECP, those benefits lasting several years. These results have been reported in peer-reviewed papers produced by specialists and thus should be taken seriously. Limited experience in the UK with a much smaller patient group over a short period shows similar qualitative improvements, experience confirmed by objective reports from other parts of Europe. One should always retain a degree of scepticism where the equipment is only available from one supplier – who therefore has a vested interest in the widest possible takeup of the procedure. Fortunately there are at least three significant American manufacturers, together with suppliers from other parts of the world. However, the availability of independent peer reviewed results is a safeguard, reinforced by the recent UK and European experience.

How it works

How is it that pressure pulsations in the bloodstream can have so many beneficial effects? It borders on the magical, but to get an insight into what happens one needs to understand something of how the heart itself works. There is the short explanation and the not so short explanation. The reason for two versions is that, while a lot is known about the mechanisms of the heart, there is still a lot to find out. EECP undoubtedly has both very marked effects and very subtle effects on the heart’s operation. How these various effects work together is still the subject of extended research and so, until the research effort comes up with the definitive answers, one has to rely on an educated guess (hypothesis) about what is happening.

The Short Explanation – or Plunge and Sponge

If you have a blockage in your sink outlet then the first line of attack is with a plunger, pressing up and down on the handle. This causes the column of water before the blockage to move, hopefully releasing the blockage. More precisely you are causing a pressure wave in the pipe as you press down on the plunger. The same is happening with the pressure cuffs on your legs; as the air pressure is applied by the cuff outside the leg so a pressure wave is generated inside the artery, the wave travelling up the femoral artery to the aorta, the main outlet artery from the heart.

Where there is a pressure wave there is also an increase in flow; the Plunge analogy with a blocked sink should not be taken too far, however – it is rare for a blood vessel blockage to be cleared in such a crude fashion, indeed it could be dangerous. The maximum air pressure used is chosen to avoid such a drastic effect. The increase in flow is thought to have several beneficial consequences, particularly in stimulating the production of chemicals, causing the artery to increase in diameter (vaso-dilation)and also promoting the growth of new side arteries (angiogenesis) allowing the blood to diffuse into the heart muscle. These new side arteries also help to bypass existing blockages.

The Sponge analogy refers to the heart muscle itself ; it contracts and relaxes every heartbeat. One of the results of heart disease is that the heart muscle becomes less flexible and thus blood cannot diffuse as easily to the cells of the heart muscle, cutting the energy available , the result being a weaker pumping action, starving the blood supply to the rest of the body. Where the disease has progressed further, parts of the heart muscle are put out of action, completely so where a heart attack has occurred.

Anything that therefore improves the action of the heart muscle will tend to reverse the progress of the disease.

When the pressure wave arrives in the coronary artery not only does it encourage the flow of blood along the artery, it increases the pressure pushing the blood through the artery wall and diffusing into the cells of the heart muscle. To understand the effects, put the fingers of one hand together, place them over your mouth and breathe through them. If the fingers are tightly clamped to each other it is difficult to breathe. If they are loose then it is easy to breathe. The harder you blow (increasing the pressure) the more air passes through. So if the heart cells are inflexible and tightly bound to each other then the blood can only diffuse through with difficulty. Increasing the arterial pressure will therefore cause more blood to flow through a stiff muscle. Improved blood flow will help the heart cells themselves to become more flexible, changing the chemical and energy balance of individual cells. The muscular sponge is diffused with more blood and therefore more energy. More energy means the heart can pump more efficiently – more blood pumped around the body. A virtuous circle of improvement.

EECP therefore makes sense – improved blood flow in the heart without invading the body. Great benefits without expensive advanced surgery and intensive nursing.

The Not so Short Explanation

A Potted Physiology of the Heart for non-Medical Types

The heart pump works by regular contraction and relaxation of the heart muscle around 4 chambers through which the blood flows, one way valves at the entrance and exit of each chamber allowing the blood pressure to increase to overcome the resistance of the body’s blood vessels. To do this 40 million times a year the heart needs a very reliable control system and a source of energy.

The cells of the heart muscle are different to a normal muscle, reacting automatically to changes in electrical voltage to contract and relax. The signals causing the contraction and relaxation are themselves generated in a part of the heart called the sino-atrial node. The strategic control (go faster, go slower ) comes from the brain and nervous system, the detail control is within the heart itself.

The energy for the heart to work comes from arterial blood; this is provided primarily through the coronary arteries. These spread out into a network of capillaries and fresh blood for each heart cell diffuses through from the capillaries. If insufficient blood is available, either due to blockages in the coronary arteries or faulty diffusion then the cells go short of energy and cannot operate properly. The result is very often angina or worse, heart attack.

Blockages or restrictions in the coronary arteries can occur because of atheroma, the build-up of fatty deposits. These build up in the walls of the coronary arteries and narrow the diameter of the artery. Narrowing also occurs as part of the body’s own control mechanism; the need for blood supply in the body varies all the time and one of the range of controls is to widen or narrow the blood vessels to cause less or more resistance to flow as required at the time. The body has a range of hormones and enzymes that control the diameter of each blood vessel, release of which is controlled by the nervous system. Clearly these have to operate very rapidly – just think how quickly you blush when embarrassed or excited! These hormones and associated chemicals have their main effect at the surface wall of the blood vessel – the endothelium, causing the cells to relax or contract. Narrowing is controlled by one set of chemicals and expansion by another set, so keeping the balance from second to second is crucial to the heart’s (and your) wellbeing.

If atheroma interferes with the flow of blood, so also will it interfere with the arrival and reaction of the control chemicals at the endothelium, reinforcing the spiral of ill effects. Some of the drugs prescribed for heart problems are designed to help the process of relaxation of the blood vessel, both improving the flow of blood and supplementing the natural reactions near the wall of the vessel. If these methods do not work properly, e.g. because too much fatty tissue interferes with flow even with medication and changes in lifestyle, the cardiologist will try to resolve the problem by either placing a stent in the diseased section or bypassing it completely with a graft. Both these are drastic interventions and EECP has been developed as another procedure to add to the battery of alternatives available, with the advantage of being non-invasive.

Note also that atheroma occurs not only in the large coronary arteries, but also in the much smaller capillary network – the essential interface to the heart muscle cells, again leading to flow restrictions and blockages in that area.

Pressure Waves and Flow in the Coronary Arteries

So how does a pressure pulse supplement the chemical processes occurring at the wall of the blood vessel and the diffusion of blood through the heart muscle? Recall that the leg cuffs are triggered at the point of closure of the aortic valve – the heart muscle has started to relax, which in turn removes the squeeze on the coronary arteries themselves, lowering their resistance to blood flow – the diameter increases. The coronary arteries are connected to the aorta just above the aortic valve so the pressure pulse sweeps into the coronary arteries with very little resistance. Because the aortic valve is closing, it does not affect the inside of the heart chamber (ventricle) in the same way.

This is where medicine and engineering get very close to each other as disciplines. Engineers get very interested when pressure waves occur in tubes because they cause several effects, especially at the surface boundary of the tube. Flow in anything - a tube, the atmosphere, a blood vessel - occurs because of a difference of pressure, the greater the difference - the greater the flow. A rapid change in pressure causes a rapid change in flow and, because of the friction caused by the uneven surface of the tube, these flow changes cause vortices. Vortices effectively stir up the fluid, leading to a speeding up of any chemical process that may be occurring. A good analogy for this effect is that of stirring a cup of tea (a vortex) to get the sugar to dissolve more rapidly. Hence the hypothesis is that an EECP pressure wave causes a significant improvement in the production and balance of the chemicals controlling the dilation and contraction of the coronary arteries – a good thing!

Pressure difference causes flow not just along the blood vessel, but also through the wall of the vessel. At this point of the cycle, the heart muscle is relaxing so the size and shape of the individual cells is increasing, as is the space between the cells, reducing the resistance to flow of blood – diffusion – through the structure of the heart muscle. If the pressure difference is then boosted by the pressure wave in the coronary artery, so the flow will also be increased – another good thing because the flow of oxygen to the cells is improved. There is some evidence also that EECP has a large effect on micro-capillary atheroma by promoting angiogenesis (working around the blockages) and vaso-dilation. This again increases the surface area available for diffusion of blood.

The result is that angina – essentially a signal that the heart muscle does not have enough oxygen to meet the demand upon it – should be reduced or, perhaps, even eliminated.

Experience as a patient

Every patient with coronary disease is unique. Each individual’s problem is made up many factors:- age, sex, genetic background, physiology, extent and degree of coronary and other disease, etc. The combination of these factors means that the individual’s response to treatments available is going to be different. Therefore it is difficult for the health care professional to be certain of the outcome of any individual course of treatment. He/she has to work from a combination of observation and shared experience in recommending any treatment.

This caution is as true with EECP as any other treatment. However, as already noted, it has great benefits from the patient viewpoint. One of the best medical principles is ‘Primum, non Nocere’ – ‘First, Do no Harm’ , and EECP certainly scores highly in this respect. . Because each patient has a unique set of symptoms inevitably, however, there will be a minority who will be disappointed, experiencing no perceived benefit. Clearly practitioners and websites discussing EECP will accentuate the positive aspects; therefore peer-reviewed results in medical papers are vital in evaluating the effectiveness of EECP

The experience of each patient is also an essential input both for the professionals evaluating the procedure and for patients contemplating a course of treatment. The reaction is overwhelmingly positive; there are several blogs and message threads showing these reactions [references TBA]. Most of these were generated during 2002-2004; for some reason more recently treated patients have been more reticent even though the results are still very good. The author – who has recently finished a course of treatment in the UK – has had an amazing outcome, far better than hoped for. No Angina!

It is hoped to develop a discussion, especially in the European context, of EECP, its benefits and background theory, to widen its availability in Europe. There are a lot of severely disabled patients who could benefit very quickly.

The discussion will, I hope , also cover the health economic benefits within the large state- funded medical systems in Europe such as the NHS in the UK

  ¶ 3:49 pm

  Heart Disease & EECP in Europe This blog has been set up for patients to share their experience in the use of EECP - External Enhanced Counterpulsation - to alleviate their symptoms of heart disease, especially angina. EECP in the United States has been extensively covered on the Internet, both professionally and for patient experience. It has also been used as a procedure in other parts of the world - indeed much of the early work was done in China.

EECP has been used also in Europe and I felt it would be useful to new and existing patients to relay some background and experience in the European context. European health systems are different to the US and the use of EECP could be vastly expanded with a corresponding increase in the quality of life for many people. I believe also that with the right organisation significant savings in healthcare support budgets for angina and heart failure patients can be made. Hence this blog has been set up . I hope that it will both help potential patients to understand more rapidly what is involved and also attract comment and information from health care professionals on its use.

Much of the information available on EECP has been written for medical professionals and is surrounded by a dense thicket of jargon, making it difficult for most people to follow. I am an engineer who has benefited very much from a course of EECP and I hope to post a description of the procedure that I hope will be easier to understand. I'll try to avoid engineering jargon! - we're just as bad as any other profession.

HP Masher - Rye Harbour UK  ¶ 3:28 pm