27th November 2018
A number of people have written to me asking how to read all the articles I have written on cardiovascular disease. I understand it is not exactly easy to do this. So, here I am going to attempt a short summary of everything I have written up to now.
Thrombogenic theory vs. LDL/cholesterol hypothesis
Since the mid-nineteenth century there have been two main, and almost entirely conflicting, hypotheses as to what causes cardiovascular disease. At present it may seem as if there is only one, the cholesterol or LDL hypothesis. Namely that a raised low-density lipoprotein is the underlying/primary/necessary cause.
I am not running through all the reasons why this hypothesis is wrong here. I will confine myself to one simple point. For the LDL hypothesis to be correct, it requires that LDL can travel past the lining of the artery, the endothelial cells, and into the artery wall behind. This is considered the starting point for atherosclerotic plaques to form.
The problem with this hypothesis is that LDL cannot get into any cell, let alone an endothelial cell, unless that cell wants it to. We know this, for certain, because the only way for LDL to enter any cell, is if the cell manufactures an LDL receptor – which locks onto, and then pulls the LDL molecule inside. There is no other passageway. This is an inarguable fact.
If LDL cannot enter a cell, unless allowed to do so, then it cannot pass through a cell, unless a cell wants it to. It most certainly cannot exit the other side of a cell, unless granted passage.
Others have argued that, oh well, the LDL simply slips through the gaps between endothelial cells and that is how it gets into the artery wall. Again, this is impossible. There are no gaps between endothelial cells. Endothelial cells are tightly bound to each other by strong protein bridges, known as ‘tight junctions.’
These tight junctions can prevent the passage of single ions – charged atoms – which makes it impossible for an LDL molecule to slip through, as it is many thousands of times bigger than an ion. This, too, is an inarguable fact. Ergo, the initiation of an atherosclerotic plaque (the underlying problem in cardiovascular disease) cannot be triggered by LDL leaking into an undamaged artery wall.
Which means that, if you want to get LDL (or anything else) into the artery wall, you first must damage the endothelium/lining of the artery. This has been accepted by the mainstream medical world, although you wouldn’t really know it, because they don’t exactly shout it from the rooftops.
Here, however, is a quote from the National Heart Lung and Blood Institute in the US. An organisation which is as mainstream as it gets:
Research suggests that coronary heart disease (CHD) starts when certain factors damage the inner layers of the coronary arteries. These factors include:
- High levels of certain fats and cholesterol in the blood
- High blood pressure
- High levels of sugar in the blood due to insulin resistance or diabetes
- Blood vessel inflammation
- Plaque might begin to build up where the arteries are damaged
It has taken them a long time to admit that damage must come first, but it is inescapable when you think about it. For once, I am completely in agreement with the mainstream on this, the initial step.
However, it is what happens next, where we rapidly diverge in our thinking. The mainstream believes that, after damage has occurred, it is LDL, and only LDL, leaking into the artery wall that triggers a whole series of downstream reactions that lead to plaques forming.
However, once you have damaged the endothelium there is no longer a barrier to stop anything getting into the artery wall. So, why pick on LDL? You also have proteins, red blood cells, platelets and Lp(a) and VLDL. Indeed, anything in the bloodstream now has free entry.
It particularly makes no sense to pick on LDL, as there is already plenty of LDL in the artery wall to start with. It gets there via the vasa vasorum (blood vessels of the blood vessels) which supply the largest blood vessels with all the nutrients they need, and through which LDL can freely flow into, and out of, the artery wall.
Which begs a further question. Why should the LDL that gets into the artery wall, from the blood flowing through the artery, cause a problem, when the LDL that is already there – does nothing? The more you look at it, the more ridiculous the LDL hypothesis becomes.
A counter hypothesis is as follows.
If you damage the endothelium, the first thing that happens is that a blood clot forms at that point. This has been known for a long time. I was sent an article a while ago, written as far back as 1959. The findings stand today:
‘…any intimal injury can very easily precipitate a local process of coagulation, platelet agglutination and fibrin deposition.’1 [a.k.a. a blood clot]
You may wonder where the word ‘intima’ just appeared from. The endothelium, and the thin layer underneath the endothelial cells is sometimes called the ‘intima.’ Sometimes it is called the endothelial layer, some people call it the epithelium, or the epithelial layer. What you never get, in medicine, is people calling it the same thing… the same damned thing. Thank God these people don’t make aeroplanes, is all I can say.
Anyway, damage the endothelium, and a blood clot will form. This is the main mechanism the body uses to stop itself from bleeding to death. Damage the artery/endothelium → underlying artery wall exposed → blood clot forms → life continues.
What then happens? Well, most of the blood clot is shaved down in size by plasmin, an enzyme designed to break up (lyse) blood clots. Then a new layer of endothelium grows over the top of the remaining blood clot, and in this way, the clot becomes incorporated into the artery wall. Although I have added in a few extra bits, this is, essentially, the thrombogenic theory, first suggested by Karl von Rokitansky in 1852.
He proposed this because he noted that atherosclerotic plaques looked very much like blood clots, in various stages of repair. He further observed they contained red blood cells, fibrin and platelets, which are the main constituents of a blood clot. His ideas were then rubbished by Rudolf Virchow, who could not see how a blood clot could end up underneath the endothelium, and Rokitansky’s theory (almost) died a death.
However, from time to time, other researchers also noted that plaques do look awfully like blood clots. For example, a researcher called Elspeth Smith – who taught me at Aberdeen University. She had this to say
‘…in apparently healthy human subjects there appears to be a significant amount of fibrin deposited within arteries, and this should give pause for thought about the possible relationship between clotting and atherosclerosis.’ 2
As her paper went on to say:
‘In 1852 Rokitansky discussed the “atheromatous process” and asked, “In what consists the nature of the disease?” He suggests “The deposit is an endogenous product derived from the blood, and for the most part from the fibrin of the arterial blood”. One hundred years later Duguid demonstrated fibrin within, and fibrin encrustation on fibrous plaques, and small fibrin deposits on the intima of apparently normal arteries. These observations have been amply confirmed but, regrettably, the emphasis on cholesterol and lipoproteins was so overwhelming that it was another 40 years before Duguid’s observations had a significant influence on epidemiological or intervention studies.’
Finally, for now, Dr Smith stated this in another paper:
‘After many years of neglect, the role of thrombosis in myocardial infarction is being reassessed. It is increasingly clear that all aspects of the haemostatic system are involved: not only in the acute occlusive event, but also in all stages of atherosclerotic plaque development from the initiation of atherogenesis to the expansion and growth of large plaques.’3
What she is saying here is that every step of CVD is due to various aspects of blood clotting. You damage the artery wall, a blood clot forms, it is then incorporated into the artery wall. A plaque starts, then grows. This description of how CVD starts and develops, is the process that I believe to be correct. With a couple of provisos.
The main proviso is that endothelial damage is going on all the time, in everyone’s arteries, to a greater or lesser extent. Therefore, we are not looking at an abnormality, or a disease, or a ‘diseased’ process.
The formation of blood clots following endothelial damage is also a healthy, normal, process. If it did not happen, then we would all bleed to death. As can happen in haemophilia, where blood clots do not form properly, due to a lack of clotting factors.
The next normal healthy process is that any blood clots that form must be incorporated into the artery wall. That is, after having been stabilised and shaved down. If clots simply broke off and travelled down the artery, they would get stuck when the artery narrows and cause strokes and heart attacks – and bowel infarctions and suchlike.
In short, the only way to repair any blood clot that forms on the lining of an artery wall, is to shave it down, then cover it over with a new layer of endothelial cells. Incorporating it into the artery wall.
At which point, repair systems swing into action. The main repair agents are white blood cells called macrophages. These break down and digest any remnant blood clot, before heading off to the nearest lymph gland where they too are broken down, with their contents, and removed from the body.
This ‘repair’ process leads to, what is referred to as ‘inflammation’ in the artery wall. Once again, however, this is not a disease process, it is all quite healthy and normal.
Problems only start to occur when the rate of damage, and resultant blood clot formation, outstrips the ability of the repair systems to clear up the mess.
damage > repair = atherosclerosis/CVD
repair > damage = no atherosclerosis and/or reversal of plaques.
What factors can lead to the situation where damage outstrips repair? First, we need to look at those factors that increase the rate of damage. There are many, many, things that can do this. Here is a list. It is non-exhaustive, it is in no particular order, but it may give you some idea of the number of things that can cause CVD, by accelerating endothelial damage:
- Systemic Lupus Erythematosus
- Use of oral steroids
- Cushing’s disease
- Kawasaki’s disease
- Rheumatoid arthritis
- High blood pressure
- Air pollution
- Lead (the heavy metal)
- High blood sugar
- Erythema nodosum
- Rheumatoid arthritis
- Low albumin
- Acute physical stress
- Acute mental stress
- Chronic negative mental stress
- Chronic Kidney Disease
- Sickle cell disease
- Diabetes/high blood sugar level
- Bacterial infections
- Viral infections
- Vitamin C deficiency
- Vitamin B deficiency
- High homocysteine level
- Chronic kidney disease
- Acute renal failure
- Angiotensin II
- Activation of the renin aldosterone angiotensin system (RAAS) etc.
Blimey, yes, that list was just off the top of my head, I could get you another fifty without much effort. And no, I did not just make it up. I have studied every single one of those factors, and many more, in exhaustive detail. The extent of how many factors there are, should not really come as a surprise to anyone, but it usually does.
After all, the bloodstream carries almost everything around the body, and the endothelium faces the bloodstream, it is the first point of contact. If damaging things are being carried about in the blood, the lining of the artery is going to be directly exposed to enemy attack.
Moving on, we need to look at factors that make the blood more likely to clot and/or make blood clots that are more difficult to shift. Again, in no particular order here and non-exhaustive:
- Raised fibrinogen levels
- High lipoprotein (a)
- Antiphospholipid syndrome (Hughes’ syndrome)
- Factor V Leiden
- Raised plasminogen activator inhibitor 1 (PAI-1)
- Raised blood sugar levels
- High VLDL (triglycerides)
- Stress hormones/cortisol
- Non-steroidal anti-inflammatory drugs (NSAIDs)
- Acute physical stress
- Acute mental stress.
For good health, you want to maintain a balance between the blood being too ready to clot, and the blood not clotting when you need it to. If you turn down the blood clotting system, bleeding to death can be a problem. This can happen if you have haemophilia, or if you take warfarin – or any of the other drugs used to stop blood clots forming in Atrial Fibrillation. Aspirin can also lead to chronic blood loss, and anaemia.
Looking at it from the other angle. You do not want your blood to clot too rapidly, or else equally nasty problems can occur. Antiphospholipid syndrome (APS), is a condition where the blood is highly ready to clot (hyper-coagulable). It greatly increases the risk of CVD:
‘Patients with APS are at increased risk for accelerated atherosclerosis, myocardial infarction, stroke, and valvular heart disease. Vascular endothelial cell dysfunction mediated by antiphospholipid antibodies and subsequent complement system activation play a cardinal role in APS pathogenesis.’4
Just to look more closely at one other factor on the list, which is fibrinogen. This is a short strand of protein that is made in the liver. It floats about in the blood doing nothing very much. However, if a clot starts to form, or the clotting system is activated, fibrinogen ends up being stuck end-to-end to form a long thin, sticky protein strand called fibrin. This is a bit like the strands that make up a spider’s web.
Fibrin wraps around everything else in a blood clot and binds it all very tightly, creating a very tough plug. You would guess that if you have excess fibrinogen in the blood, more fibrin will form, creating bigger and more difficult to shift blood clots. I was first alerted to the dangers of having a high fibrinogen level by the Scottish Heart Health study.
‘This large population study confirms that plasma fibrinogen is not only a risk factor for coronary heart disease and stroke, but it is also raised with family history of premature heart disease and with personal history of hypertension, diabetes, and intermittent claudication.’ 5
To my surprise, a raised fibrinogen was found to be the most potent risk factor in the Scottish Heart Health Study, ranking above smoking. Because I don’t want to make this blog too long, I will simply say that all the other things in the list above both increase the tendency of the blood to clot and increase the risk of CVD.
Finally, we can look at factors that impair the repair systems. There are two basic parts to the repair systems.
- Formation of a new layer of endothelium, to cover the blood clot
- Clearing away of the debris left by the blood clot within the artery wall
What sort of things stop new endothelial cells being created?
- Age – which reduces endothelial progenitor cells (EPC) synthesis
- CKD – reduces EPC synthesis
- Activation of the renin-angiotensin aldosterone system (RAAS)
- And drug that lowers nitric oxide synthesis
- Lack of exercise.
What sort of things damage the clearance and repair within the artery wall?
- Chronic negative psychological stress
- Certain anti-inflammatory drugs
- Many/most anti-cancer drugs.
Knowing this, it seems counter intuitive that there has been a great deal of interest lately in using anti-inflammatory drugs to reduce the risk of CVD. My response to the idea that inflammation may cause CVD has always been that, the most potent anti-inflammatory agent known to man is cortisone/cortisol. This is one of the stress hormones, and it vastly increases the risk of CVD. As do immunosuppressants – which are also used to dampen down the inflammatory response.
On the other hand, inflammation is not always a healthy thing. There are many chronic inflammatory conditions such as: rheumatoid arthritis, Crohn’s disease, asthma, Sjogren’s disease and suchlike where the bodies immune system goes wrong and starts to see proteins within the body as ‘alien’ and attacks them. This can cause terrible damage.
The way to best treat (if not cure) these conditions is to use immunosuppressant drugs. Cortisol/cortisone – and the many pharmaceutical variants that have been synthesized from cortisol – is still widely used. Hydrocortisone cream, for example, is widely used in eczema.
Immunosuppressants are also commonly used in transplant patients, to stop the organ from being attacked by the host immune system. This is a good thing to achieve, but longer-term problems with CVD are now widely recognised.
‘With current early transplant patient and allograft survivals nearly optimized, long-term medical complications have become a significant focus for potential improvement in patient outcomes. Cardiovascular disease and associated risk factors have been shown in renal transplant patients to be related to the pharmacologic immunosuppression employed.’6
‘Taking high doses of steroids (glucocorticoids) seems to increase the risk of heart disease including heart attack, heart failure, and stroke, according to new research. Steroids fight inflammation and are often prescribed for conditions including asthma, inflammatory bowel disease, and inflammatory arthritis. Prednisone and hydrocortisone are two examples of steroids.
Yet well-known adverse effects of these potent anti-inflammatory medications can increase the risk of developing high blood pressure, diabetes, and obesity — risk factors for heart disease.’7
The question I suppose is, can CVD possibly be a form of autoimmune condition? It seems highly unlikely. Although the inflammatory system can go wrong in all sorts of way. You may have heard of Keloid scars. These happen when you damage the skin, and the resulting healing response can create a very large ‘hypertrophic’ and unsightly scar.
Perhaps if you damaged the lining of an artery, and this triggered the equivalent of a ‘keloid’ scar in the artery wall, then if you could dampen down this reaction, an atherosclerotic plaque would then be much smaller. In which case, an inflammatory could be of benefit.
However, as of today, the more potent the anti-inflammatory drug, the greater the increase in CVD. Which suggests that if you interfere with the healing response to arterial injury, you are going to make thing worse – not better.
In truth, the real reason why inflammation is being seen as a possible cause of CVD is because inflammatory markers can be raised in CVD. To my mind this just demonstrates that in people with CVD, lots of damage is occurring, therefore there is more repair going on, so the inflammatory markers are raised.
However, the mainstream has decided to look at this from the opposite side. They see a lot inflammation going on and have decreed that the inflammation is causing the CVD – rather than the other way around. Frankly, I think this is bonkers. But there you go.
Anyway, where has all this got us to. I shall try to achieve a quick summary.
The LDL hypothesis is nonsense, it is wrong, and it does not remotely fit with any other factors known to cause CVD.
The thrombogenic theory, on the other hand, fits with almost everything known about CVD. It states that there are three, interrelated, processes that increase the risk of CVD:
- Increased rate of damage to the endothelial layer
- Formation of a bigger or more difficult to remove blood clot at that point
- Impaired repair/removal of remnant blood clot.
Any factor that does one of these three things can increase the risk of CVD. Although, in most cases, a few factors probably need to work in unison to overcome the body’s ability to heal itself. Which means that people who have only one or two risk factors, are probably not going to be at any greatly increased risk. You need to have three or four, maybe more, and then things really get going.
There are a few things that I have mentioned that will greatly increase the risk of CVD with no need for anything else to be present. They are:
- Steroids/Cushing’s disease
- Chronic Kidney Disease
- Sickle cell disease
- Antiphospholipid syndrome
- Systemic Lupus Erythematosus
- Kawasaki’s disease.
All of which means that – in most cases – CVD has no single, specific, cause. It should, instead, be seen as a process whereby damage exceeds repair, causing plaques to start developing, and grow – with a final, fatal, blood clot causing the terminal event. The next blog will be a review of the things that you can do to reduce your risk of CVD.
1: Astrup T, et al: ‘Thromboplastic and Fibrinolytic Activity of the Human Aorta.‘ Circulation Research, Volume VII, November 1959.