Cecil’s understanding of electrical connections in different hearts fascinated me from a clinical point of view. While one might wonder if some day we could find a way for pacemakers to enhance our heart’s abilities beyond normal human capacity, my interest was more immediate than that.
I wanted to find out how we can get the most out of what nature has already provided us.
Even though the medical community (including Cecil) did not understand how the wiring system functioned in the ventricles after impulses leave the Purkinje system… perhaps there was a way that pacemakers could use the conduction system already in the ventricles (rather than bypass it as they presently do by directly stimulating ventricles).
A new goal loomed on my horizon.
Heart Movement: The Natural Order of Things
The motion of the heart is like a cardiac symphony, with different areas contracting in sequence as they are activated, each playing their part precisely.
My focus now turned toward finding a way for pacemakers to preserve this complex series of motions. We knew that the QRS was simply an ignition key – the initiation of electrical activity that stimulated the efficient natural system that exists within the ventricles.
Recognizing this, I saw my true task: find a way to stimulate the bundle of His directly — and allow the heart’s own conduction system to transmit those electrical impulses to the rest of the heart in its natural fashion.148 In this way, we might preserve the heart’s natural twisting function and help almost a third of the patients who do not get satisfactory improvement following conventional pacemaker treatment.
I knew the potential benefit to patients was vast, since over 5 million patients in the United States have pacemakers, and over 1 million patients worldwide receive new or replacement pacemakers (such as when the prior pacemaker’s battery depletes) every year. These numbers reflect an astounding pool of people who could benefit by having their hearts’ electrical support delivered into their natural conduction pathways.
Praise for Pacemakers
It should be noted again that despite the cited drawbacks to how nearly all of these medical devices are wired into the body, ventricular pacemakers as used now do have enormous lifesaving importance. Electrical firing from these units prevents sudden death in patients who have complete heart block (where electrical impulses do not travel from the atrium to the ventricle). It also bestows a more rapid heart rhythm to patients with slow heart rates (below 50 beats per minute).
Still, direct ventricular stimulation will only cause the heart to squeeze, but can never restore the natural sequential twisting motion. It may even cause heart function to worsen, and possibly instigate heart failure in patients with dilated hearts.149 The frequency of these specific adverse effects is uncertain, but it is known that at least 30% of patients receiving pacemakers do not obtain clinical improvement.143, 145 This could mean patients who had symptoms of easy fatigue will not improve. If they had shortness of breath, that will not change.
Willie Sutton: Go Where the Money Is
Admittedly, the pursuit of a medical approach to restore a heart’s natural contraction rhythm is not a typical one for a cardiac surgeon. It is the cardiologists known as electro-physiologists that usually conduct this type of treatment. Surgeons rarely put in pacemakers today, except when we find the heart isn’t working correctly (as when there’s a heart block) at the conclusion of an operation. We then insert the leads and implant the pacemaker.
Given all this, why would I (a surgeon) be drawn to uncovering a way to directly stimulate the bundle of His? My answer would mirror the reply given by Willie Sutton, the famed bank thief, who when asked why he robbed banks, replied, “Because that’s where the money is.”
My curiosity led me to the bundle of His because “that’s where the money is.” From there, we may stimulate electrical nerve transmission along normal circuitry. Yet theory is only as good as it can be shown to reflect reality. This still needed to be tested: if the leads of a pacemaker were placed in this bundle of His… would it re-establish the sequential heartbeat that restores natural twisting action?
Testing the Theory
This is what I hoped to find out experimentally. But to do that, I had to find a way to access the bundle of His in order to place a pacemaker’s leads. (Figure 3) I needed to discover some means to get to this internal site from outside the heart. We certainly did not want to perform open-heart surgery to place the leads of a pacemaker.
Figure 3: Anatomic display of electrical circuitry, showing bundle of His, left bundle and its fan-like splay of bundle branches, and how Purkinje fibers only touch the surface of ventricle muscle.
Trying to figure this out in my lab, I had the idea to unravel Paco’s model of the helical ventricular myocardial band as my guide. Unfolding the heart replica, I first found where the bundle of His was exactly represented on the top of the septum. (Figure 4)
Figure 4: Identification of septum bundle of His by Torrent-Guasp model. It exists where the basal loop folds to start the helix. Clearly evident, this site is called “septum bundle” in these two images.
I then folded the heart model back together and determined that if we punctured the ventricle through a specific location… we could thread wire leads through it to reach the top of the septum that contains the bundle of His!150
I clearly saw its location work on the model. But would it work in reality?
On an animal test subject, we selected the puncture site outside the top of the right ventricle and inserted a lead through a needle conduit into the location. (Figure 5)
Figure 5: By using a top view of anatomic landmarks of the heart’s surface, we insert a catheter (with a pacer wire, represented by arrow) into the upper septum. This is done by entering from the pulmonary artery, advancing it into the left ventricle, and implanting the wire on top of the septum. Another example of using this model to answer a riddle never before solved.
With everything in place, it was time to simulate the stimulus of a pacemaker. It was, as we say, the moment of truth.
The result was immediately obvious, as a normal twisting beat followed each electrical stimulation! We had successfully reproduced the heart’s ability to pace by the natural pathway! It was unbelievable! We were thrilled (though not entirely surprised, since we had simply followed nature).
We had paced the right atrium and stimulated the bundle of His — and restored the natural twisting action. The consistency of our success was confirmed by additional studies on more animals — we reached the bundle of His every time. But truthfully, one look was worth a thousand words, as my two research fellows and I witnessed as the heart began twisting again. The success of our search to generate pacing via the natural conduction pathways meant that Willie Sutton had found the bank.
Ours was Not the Only Study. So Where are the Changes?
Interestingly, my further exploration of the medical literature revealed that we were not the only ones testing this approach. I uncovered groups of cardiologists who had done what we had. These experienced electro-physiologists reported superb findings after they used pacemaker leads to stimulate the bundle of His,151–153 but their findings were not well publicized. Their results avoided the abnormal heart contractions that were typically produced by today’s pacemakers that place the leads in a manner that Wiggers had warned us about 90 years ago. Clearly, we were long past due for a new pacemaker treatment approach that would restore a natural twisting motion to our patients’ hearts.
We were excited by the enormous volume of candidates that could benefit from this new approach. This included patients with slow heart rates (called bradycardia), those with wide QRS intervals (their EKG showing different parts of their heart being stimulated in an abnormal pattern), those having left bundle branch block (“LBBB” — a blockage in the left branch of the bundle of His), and of course, those with uncoordinated heart contractions from traditional pacemakers stimulating the RV apex.
Despite all thi
s, progress in making changes in the use of pacemakers has not occurred. Even though the limited number of reports so far has consistently documented excellent findings — interest in pursuing this new approach has spawned scant studies.
In 2010, only 59 patients were included, but this was the world’s largest report of the great success that followed bundle of His pacing.154 A more recent study on 75 patients receiving bundle of His pacemakers has reported an 80% success rate in ventricular performance at a follow-up 12 months after pacemaker placement.153
Perhaps more frustratingly, an eight-year combined South European and Southern Italy study reported on just 570 patients treated by pacemakers that stimulated the bundle of His or its adjacent fibers. While larger than the other studies, 570 is still a tiny number considering there are many millions of people who need pacemakers worldwide. Predictably, each of these 570 patients developed a normal electrocardiogram pattern, with functional ventricular contractions that matched those of athletes (the study compared their results to athletes, since athletes could be regarded as having the epitome of healthy heart function).151
They too published results proving the advantages of stimulating the heart’s natural ignition point, but nobody wanted to listen. These dramatically improved outcomes have not altered conventional cardiac approaches. It seems that even with other available pacing options, many physicians continue wearing the same shoes, even though the toe is still being stubbed.
Persistence of Resistance
So why would there be opposition to change when the pool of those who could benefit is so vast? Well, this “sea change” demands significantly different actions from pacemaker manufacturers and from cardiology electro-physiologists, and that is the likely problem.
Manufacturers would have to redesign and produce new types of pacemakers and leads, but they already have a willing and eager marketplace for those they presently make. Cardiology electro-physiologists would have to learn new techniques, rather than perform the ones they have “successfully” used for years. They would need to give up the current simplicity and ease of quickly installing leads at the apex stimulation site. But this kind of thinking reflects a physician-related benefit — rather than a choice that may optimally serve the patient.
Nobody wants to change from a system that is already making a lot of money. It would require an investment of funds by manufacturers. Plus, it would involve an investment in education by the cardiologist. Acquiring proficiency in this new method is a little harder at first, but once learned, the procedure only requires about 20 more minutes. Yet such a learning curve must be undertaken before any new approach can be done smoothly and easily.
But the now-documented benefits of pacemakers utilizing the heart’s normal circuitry should justly override those considerations, as it improves upon a treatment still producing the abnormalities first described in 1925.
Today, cardiologists and electro-physiologists still have not embraced the benefits of using natural circuitry when placing pacemakers. This attitude will hopefully change following their appreciation of ongoing reports that document how its use can restore the natural twisting pattern of contraction… a goal never achieved by traditional pacemaker treatment.
Where Goeth the Electricity? The Grand Mystery
I had more than accomplished my original mission of understanding the final missing piece before publishing about Paco’s discovery. I now understood how the heart’s electrical currents cause the helical muscles to function. They must sequentially reach each muscle fiber to allow the normal twisting action to occur. Yet my search went far beyond this, as we now also had a proven approach to stimulate the bundle of His — and confirmed that its use completely restored the heart’s natural twisting and contraction movements — essential to returning normal heart function.
But there still remained a mystery.
It was an enigma unsolved by all fields of cardiology. Yet the truest tribute to learning is maintaining an openness to hear and welcome new ideas, even if they are as yet untested.
Join me on one further journey into uncharted territory.
This was our puzzle: we had identified the main “thoroughfares” over which electrical stimuli travel in the heart, including the bundle of His, the RV apex, and the Purkinje system. Yet as I have described, anatomists knew that the last part of this conduction system — the Purkinje fibers — only penetrates into 15% of the ventricular muscles in humans and then suddenly stops.
So once electricity passes over these known conduit channels — how does it get to its final destination — the muscle cells (called myocytes) that are essential to stimulating the normal twisting action that creates efficient cardiac contraction?
Nobody knew.
Yet once understood, this could open the door to innovative treatments for the heart. We simply do not know what might be possible.
My “traveling to learn” approach brought me again to Cecil Coghlan, the brilliant and distinguished cardiologist described earlier in this chapter, who shared my fascination with the helical ventricular myocardial band. It would prove to be an incredible trip.
In his office, I brought up the riddle of electrical impulses.
I knew Cecil had been searching for that answer as well. He had arrived at a theory, and revealed the “conceptual seeds” that might someday lead to a solution.147
“Heart architecture is more complex than just the two-dimensional world of electrical fibers and muscle cells,” he began. “Instead of only looking at the muscles and nerves, we should look at the framework.”
Cecil proposed that the heart was formed upon a “scaffold” of connective tissue (collagen) that served as the foundation of its natural ventricular shape. This “mesh framework” existed as a fine sheath-like layer of connective tissue that surrounded the electrical pathways (the His/Purkinje system) — as well as each microscopic heart muscle cell.
Cecil suggested, “There may be certain chemical substances in this matrix that cause the current to move so quickly. There is an intriguing tiny protein in anatomy called proteoglycans that in part bind water and cations (positively-charged ions, such as sodium and potassium) within the internal cellular structures.”
Not familiar with them, I asked, “You believe they might be part of this matrix?”
“Yes, and they may in some way act like little generators to spread the electrical impulses quickly and smoothly along this entire framework and the ocean of muscle fibers.”
My eyes were opened. I listened intently as Cecil explained that electrical impulses could move from cell to cell by what he called “proton hopping.” This process would transmit the impulses over the surface of each muscle cell. It could do this at a velocity that is consistent with those conduction speeds needed for the natural twisting movement, and for everything else required for the heart to function as it does.
As he finished, I finally said, “This is absolutely amazing.”
Each of Cecil’s ideas was new to me, particularly since my knowledge of electro-physiology was limited. But I believed they made sufficient sense, such that I said, “Jim Cox has invited me to create a book unveiling Paco’s work, to publish through the American Association for Thoracic Surgery’s journal as part of their Seminars on Thoracic and Cardiovascular Surgery. I would like you to write a chapter on electricity and the heart as part of the book.”
Cecil was happy to do so. After he turned it in to me, I gave it to Jim Cox, who has spent his life learning about this. In the same manner that I have come to understand the heart, he understands electricity in ways nobody ever has before. Jim declared Cecil’s chapter the most innovative paper he had ever read on this subject.
It was creative new thinking. Of course, I knew that does not necessarily make the concept right, but bright folks with open minds (like Jim Cox) welcome new ideas. Jim wanted to ask Cecil some questions about the chapter regarding his own research. They exchanged notes. I suggested Jim co-author the chapter with Cecil, who re
adily agreed.
The Future
Cecil Coghlan made a thoughtful postulation, but subsequent testing was needed to determine if he is correct. But how to test it?
As it turns out, nature may have given us a means to evaluate his concept.
We know that heart failure patients with an enlarged dilated ventricle develop ventricular rhythm problems causing abnormal beats, sometimes progressing to develop ventricular fibrillation that causes sudden death. Could these rhythm issues occur as the ventricle dilates and stretches… because this enlargement also stretches Cecil’s proposed collagen network?
That got me thinking.
We understood that our surgical ventricular restoration returned a dilated spherical heart back to its normal elliptical shape. The result was that both natural ventricular twisting and contraction were recovered155–156 — with only rare development of sudden death.
This supported Cecil’s concept.
A return to nature, rather than use of electrical devices, had solved this otherwise lethal problem. Instead of using pacemakers to treat the rhythm problem, the rebuilt ventricular form solved the excitation-coupling issue — and proper rhythm was immediately restored. Now, we also presumed it returned the collagen network to its normal size and shape. Unknowingly, we corrected the very issue that Cecil’s theory may have suggested as the cause of lethal ventricular rhythms.
If accurate, this means we may have a different way to counter abnormal rhythms and sudden death.
Unlike previous chapters, this one ends with a question rather than an answer. As Einstein said, “The important thing is to never stop questioning.” Is Cecil’s premise correct? Further exploration certainly seems warranted, and studies should be pursued to confirm the answers.
If proven true, who knows what other kinds of extraordinary treatments might evolve from this knowledge?
Solving the Mysteries of Heart Disease Page 48
