REFLECTIONS ON CARDIOLOGY – AN INTRODUCTION
"If you listen to your heart," said the Philosopher, "you will learn every good thing, for the heart is the fountain of wisdom tossing its thoughts up to the brain which gives them form," and, so saying, he saluted the youth and went again on his way by the curving road.
- James Stephens, The Crock of Gold
“When you are sorrowful look again in your heart, and you shall see that in truth you are weeping for that which has been your delight.”
- Gibran Khalil Gibran, ‘The Prophet’
“Ah Love! Could thou and I with Fate conspire
To grasp this sorry Scheme of Things entire,
Would not we shatter it to bits - and then
Re-mould it nearer to the Heart's Desire!”
- Omar Khayyam, ‘The Rubayyat’
“A good heart is the sun and moon, or, rather, the sun, and not the moon; for it shines bright and never changes, but keeps its course truly”
- William Shakespeare
Cardiology deals with diseases of the heart. The cardiologist and the cardiothoracic surgeon have the great privilege of being close witnesses of this incredible organ, which Richard Selzer described as “pure theater throbbing in its cage palpably as any nightingale”.
We will begin our discussion of cardiology with a look at heart failure – which may be regarded as the endpoint of all cardiac disease, and look afterward at the various diseases that can lead to it in more detail. A miracle it is indeed, which makes us think, with the great Francis Bacon, that, “God never wrought miracles to convince atheism, because his ordinary works convince it.”
Before doing so, I would just like to say a few words about the heart itself, and some of its most incredible features.
It is the first organ to develop in the vertebrate embryo, and begins beating 21 days after conception, an incredibly short time. Consider this.
It took over 30 to 40 years to build some of the pyramids; and it is believed that it took thousands of people, working day and night, during the lifetime of the pharaohs) to build the pyramids. It took about three years, and hundreds of men, to build the Eiffel Tower. The Burj Al-Arab, the world’s tallest hotel and its only ‘7 star hotel’ (whatever that means) took over five years to build, between 1994 and 1999, and it is anticipated that the currently under consruction Burj Dubai, a skyscraper that is aimed to be the tallest building on earth, will be completed in September 2009; making it also the result of five years of labour. No human being can regard all of those ‘wonders’ as equal to one billionth the wonder that the heart arouses in he or she who studies it. Given the choice between the human heart, and all those wonders, there is little doubt over what we would prefer.
Furthermore, the heart develops in absolute silence, away from media hype, like a quiet genius, costing the parents of its recipient absolutely nothing, but merely the fusion of a sperm and an egg. Isn’t this incredible? The following Quranic verses come to mind, “We created man from a mingled drop to test him, and We made him hearing and seeing”. (Qur'an, 76: 2) and “Does man reckon he will be left to go on unchecked? Was he not a drop of ejaculated sperm? (Qur'an, 75: 36-37)”.
Compare this to the big and often premature media hype and praise that some of the structures listed above receive. Compare this to the cost of some of those buildings; we do not know how much the pyramids costed financially, although, as we will see in a bit, its human toll is priceless. Historians, like Russ Martin estimate that building a pyramid today should cost, “to be exact, a grand total of $1,130,390,000”. The Burj Al-Arab cost $650,000,000 to build, while the Burj Dubai has a budget of $4,100,000,000 – it may cost more or less to build.
The development of the heart does not bring about heated argument and debate, unlike those structures which are often built on the labours of the suffering and the poor.
I went very close to the Burj Al-Arab myself, lastly in 2007, and regard it quite simply as a titanic symbol of capitalism in the region. I am fortunate to see others agree with this opinion, “The Burj Al Arab has attracted criticism as well as praise, described as "a contradiction of sorts, considering how well-designed and impressive the construction ultimately proves to be." The contradiction here seems to be related to the hotel’s extreme opulence. "This extraordinary investment in state-of-the-art construction technology stretches the limits of the ambitious urban imagination in an exercise that is largely due to the power of excessive wealth." Another critic includes the city of Dubai as well: "both the hotel and the city, after all, are monuments to the triumph of money over practicality. Both elevate style over substance." Yet another: "Emulating the quality of palatial interiors, in an expression of wealth for the mainstream, a theater of opulence is created in Burj Al Arab … The result is a baroque effect". Sam Wollaston writing in The Guardian described the Burj as "...fabulous, hideous, and the very pinnacle of tackiness - like Vegas after a serious, no-expense-spared, sheik-over".
Both structures are very controversial, not just in terms of being symbols of American imperialism in the Arab world, but in terms of the way they exploit the immigrants building them, “Burj Dubai is being built primarily by immigrant engineers and workers from Pakistan, India, Bangladesh, China and the Philippines. Press reports indicate that skilled carpenters at the site earn US$7.60/day, and laborers earn US$4.00. Unions were forbidden in the United Arab Emirates up until recently, when the government announced steps to allow construction unions. On March 21, 2006, workers upset over low wages and poor working conditions rioted, damaging cars, offices, computers, and construction equipment. A Dubai Interior Ministry official said the rioters caused approximately US$1m in damage. Most workers returned the following day but refused to work. Workers building a new terminal at Dubai International Airport also joined that day's strike action.” I have seen those workers work in the scorching heat, being told off by their bosses over the slightest things, and who rest only very occasionally sipping equally hot cups of tea, the only thing they can afford. It is a truly atrocious environment.
The development of the heart is never delayed, but rather it is a very efficient process that cannot resemble anything we have. Most of those human structures face delays, and may turn into cancellations; for example, we read, “Emaar Properties announced on June 9, 2008 that construction of Burj Dubai was delayed by upgraded finishes and will be completed only in September 2009. An Emaar spokesperson said "The luxury finishes that were decided on in 2004, when the tower was initially conceptualized, is now being replaced by upgraded finishes. The design of the apartments has also been enhanced to make them more aesthetically attractive and functionally superior"”.
When I read about the development of the human heart or for that matter any organ, I cannot fail to be amased not just by how it all occurs – the differentiation and growth and development, but also by those who think that science provides all the answers. It is a new form of ignorance of the essence that is under the cloak of science.
For example – an account of the development of the heart reads as follows:
“The lateral plate mesoderm delaminates to form two layers: the dorsal somatic (parietal) mesoderm and the ventral splanchnic (visceral) mesoderm. The heart precursor cells come from the two regions of the splanchnic mesoderm called the cardiogenic mesoderm. These cells can differentiate into endocardium which lines the heart chamber and valves and the myocardium which forms the musculature of the ventricles and the atria.
The heart cells are specified in anterior mesoderm by proteins such as Dickkopf-1, Nodal, and Cerberus secreted by the anterior endoderm. Whether Dickkopf-1 and Nodal act directly on the cardiac mesoderm is the subject of research, but it seems that at least they act indirectly by stimulating the production of additional factors from the anterior endoderm. These early signals are essential for heart formation such that removal of the anterior endoderm blocks heart formation. Anterior endoderm is also sufficient to stimulate heart differientation since it can induce non-cardiogenic mesoderm from more posterior positions in the embryo to form heart.
The secretion of Wnt inhibitors (such as Cerberus, Dickkopf and Crescent) by the anterior endoderm also prevents Wnt3a and Wnt8 secreted by the neural tube from inhibiting heart formation. The notochord secretes BMP antagonists (Chordin and Noggin) to prevent formation of cardiac mesoderm in inappropriate places.
Other cardiogenic signals such as BMP and FGF activate the expression of cardiac specific transcription factors such as homeodomain protein Nkx2.5. Nkx2.5 activates a number of downstream transcription factors (such as MEF2 and GATA) which activate the expression of cardiac muscle specific proteins. Mutations in Nkx2.5 result in heart development”
And that is it – before of course the authors embark on details of the formation of the chambers, septation, valves and the major vessels. Science tells us what things occur; it is an entirely desciptive field. What does it mean to tell me that “heart cells are specified by proteins such as Dickkopf-1, Nodal and Cerebrus”. Are we not just translating common language into a technical language? The question that science will not answer is – how do these proteins do their function. How do they know their roles? How do they know when to start their action, and when to stop it? What is it that tells these proteins or differenting factors – we need a valve now, we need an endothelium now, we need muscle tissue now etc. It is clear that the design of something so incredible cannot proceed by blind chance. To those who believe in the new religion that is evolution, we ask them to combine all their great intellectual powers and try to create a heart – no a valve of a heart. They will inevitably fails, just like those who accepted the following Quranic challenge, “O mankind! A similitude is coined, so pay ye heed to it: Lo! those on whom ye call beside Allah will never create a fly though they combine together for the purpose” (22:73).
The reader may point out that scientists and engineers have designed artificial human valves – something which we will look at in more detail in the section on valvular heart disease. This is true; however, there are many problems associated with metallic heart valves, and there are many challenges that engineers face to improve their design. The most important problem is the need for lifelong anticoagulation; this is a headache for the patient, who needs to attend ‘the anticoagulation clinics’ every so often to have a blood test and check his blood is ‘thin enough’, as well as being a headache for the doctors looking after the patient (as we will see later). Warfarin remains one of my least favourite drugs.
The Wikipedia article on artificial heart valves has an excellent account of the advantages of the natural heart valves over the metallic variants, and the challenges that bioengineers face in designing an ideal metallic heart valve:
“The functioning of natural heart valves is characterised by many advantages:
Minimal regurgitation - This means that the amount of blood lost upstream as the valve closes is small. For example, closure regurgitation through the mitral valve would result in some blood loss from the left ventricle to the left atrium as the mitral valve closes. Some degree of valvular regurgitation is inevitable and natural (Fixme: Give indicative value). However, several heart valve pathologies (e.g. rheumatic endocarditis) may lead to clinically significant valvular regurgitation. A desirable characteristic of heart valve prostheses is that regurgitation is minimal over the full range of physiological heart function (i.e. complete functional envelope of cardiac output vs. heart rate).
Minimal transvalvular pressure gradient - Whenever a fluid flows through a restriction, such as a valve, a pressure gradient arises over the restriction. This pressure gradient is a result of the increased resistance to flow through the restriction. Natural heart valves have a low transvalvular pressure gradient as they present little obstruction to the flow through themselves, normally less than 16 mmHg. A desirable characteristic of heart valve prostheses is that their transvalvular pressure gradient is as small as possible.
Non-thrombogenic - As natural heart valves are lined with an endothelium continuous with the endothelium lining the heart chambers they are not normally thrombogenic. This is important as should thrombus form on the heart valve leaflets and become seeded with bacteria, so called "bacterial vegetations" will form. Such vegetations are difficult for the body to deal with as the normal physiological defense mechanisms are not present within the valve leaflets because they are avascular and largely composed of connective tissue (Fixme: Create article discussing the pathgonesis of leaflet bacterial vegetations.). Should bacterial vegetations form on the valve leafets they may continually seed bacteria into the arterial tree which may lead to bacteremia or septicaemia. Portions of the vegetation may also break off forming septic emboli. Septic emboli can lodge anywhere in the arterial tree (e.g. brain, bowel, lungs) causing local infectious foci. Even dislodged fragments from non-infectious vegetations (Fixme: Is this the correct terminology?) can be hazardous as they can lodge in, and block, downstream arteries (e.g. coronary arteries leading to myocardial infarction, cerebral arteries leading to stroke). A desirable characteristic of heart valve prostheses is that they are non or minimally thrombogenic.
Self-repairing - Although of limited extent compared to well vascularised tissue (e.g. muscle), the valve leaflets do retain some capacity for repair due to the presence of regenerative cells (e.g. fibroblasts) in the connective tissue from which the leaflets are composed. As the human heart beats approximately 3.4x109 times during a typical human lifespan this limited but nevertheless present repair capacity is critically important. No heart valve prostheses can currently self-repair but replacement tissues grown using stem cell technology may eventually offer such capabilities. (State that they wear).
Rapid dynamic response”
Furthermore, engineers have tried to develop a mechanical heart, and that too has many problems:
“Human beings live for an average of between 70 and 80 years. The human heart beats some 70 to 80 times a minute, for a total of several billion times during the course of an individual’s lifetime. The Abiomed company, known for its research into artificial hearts, has stated that despite all its work, it will be unable to imitate the flawless functioning that the heart displays successfully over the years. For the company’s newly-developed artificial heart to beat 175 million beats, or about five years, appears a significant target. A product of the latest technology, this artificial heart was tested in calves before human beings, although the calves survived for only a few months. The artificial heart developed by the company has been put in safety trials in human heart failure patients in 2004. But, obviously researchers find the human heart so difficult to imitate. Steven Vogel of Duke University, a biomechanic who has also written a book on this subject, describes why: It’s that the engines we have available, whatever their power output or efficiency work so differently. Muscle is a soft, wet, contractile engine, and that’s just unlike anything in our technological armamentarium. So you can’t imitate a heart . .Like the genuine article, Abiomed’s artificial heart consists of two ventricles. There the similarity ends, however. Alan Snyder of Penn State, a bioengineer who led the research, explains the difference in these terms: “In the natural heart, you’re using muscle as a container and the container pumps on its own.” Pumps that work along the same lines as the heart contain a container and a system that pumps the fluid. In the heart, however, the container carries out its own pumping. That is the difference Snyder summarized. Researchers, wondering how to make a heart that contracts by itself, set the interior walls of the two ventricles into motion by placing a separate engine between them. This artificial heart works with a battery located in the patient’s abdomen. This battery has to be recharged continuously by radio waves emitted by a rechargable battery pack patients will wear in a harness. Our natural hearts, on the other hand, have no need of a battery for energy, because they boast an incomparable muscular design capable of creating its own energy in every cell. Another feature of the heart that can’t be replicated is the incomparable efficiency of its pulses. In fact, the heart can pump five liters of blood a minute while at rest, which can rise to 25-30 liters during exercise. Kung, Abiomed’s director, describes this extraordinary change of tempo as “a challenge that currently no mechanical device can meet.” The artificial heart made by the company can only pump 10 liters a minute at best, which is not sufficient for a great many ordinary activities. The real heart is nourished and strengthened according to its needs by the blood it pumps. Such a heart can work for 50 to 60 years with no need for repairs. The heart possesses the capacity for self-renewal, which is why it never loses its ability for uninterrupted work. This is yet another feature that makes it impossible to imitate artificially. Our heart, which scientists can only dream of matching with present-day technology, shows to us the superior knowledge of our Creator and our Great Lord—God.”
If the heart develops abnormally, usually due to defects in some of the above proteins, then the result is a series of congenital abnormalities or hypertrophic obstructive cardiomyopathy, with the end result being heart failure. Such is the kindness of God.
The heart is a perfect example of intelligent design, and cardiac failure illustrates how irreducibly complex it is. If we are to consider the causes of cardiac failure – one realises that, for normal cardiac function, we need the following:
1. A structurally normal pump – this means normal differentiation and development embryologically and as the person grows. This means normal cells throughout, normal layering (endocardium, myocardium, and pericardium), normal valves, normal venous drainage, normal output; in short a normal anatomy; with a normal and adequate blood supply and nervous supply.
2. Normal electrical (heart rate and rhythm)
3. Normal muscular function (contractility)
4. Good arterial and fuel supply with its ignition
5. Normal venous return
6. An inexcessive afterload.
In learning about its problems, one cannot fail to be amazed by its structure and function, and the fact that it displays abundant examples of intelligent design and irreducible complexity. In learning about how people have tried to emulate it, we learn how majestic and superior God’s creation is, and must only say how truthful are God’s words:
“O mankind! A similitude is coined, so pay ye heed to it: Lo! Those on whom ye call beside Allah will never create a fly though they combine together for the purpose. And if the fly took something from them, they could not rescue it from it. So weak are (both) the seeker and the sought!” (22:73).