Saturday, September 3, 2016
Progress in Endoluminal Treatment of Coronary Artery Blockages.....from balloon to disappearing magnesium stents...40 years of progress in cardiology
Dr Andreas Grunzig, a German physician-radiologist, in 1974 performed the first ground breaking balloon angioplasty in an awake human patient, in a Zurich hospital. In Germany, then, he would have lost his medical practising license due to great inertia from fellow colleagues and seniors who thought this kind of procedure was only for experimentation in pigs and cattle.
[ https://www.youtube.com/watch?v=v5FFTZTvTiQ ]
I was a cardiological research registrar in the cardiology department at St Bartholomews Hospital in central/east London, the business and high finance side of London, way back in 1981.
Even at that time, some 7 years after Grunzig's ground breaking case,my bosses at St Barts were 'tip-toeing' like pirates operating under duress,, doing their cases under the watchful and prying eyes of the 'demigods' at the hospital: the all powerful cardiothoracic surgeons. The surgeons insisted that we get ready all our patients for potential emergency surgery, if situation arise.
Way back in London in 1981, it would mean taking patients' consent for both balloon angioplasty and emergency CABG [ coronary artery bypass graft op ], a medicolegal requirement.....and getting ready five pints of grouped cross-matched blood ready for 'possible open heart surgery if plan A failed'!
.....and having all patients thoroughly shaved from the neck below, as if they are going for open heart surgery!
'These bastards are cavalier and crazy!', must be the silent common swear words from the surgeons at Barts in those dizzying days of the early eighties!
I was not involved in the actual 'crime' scene at that since I was only a research registrar , a gurkha actually, attach to another branch of cardiology, probing electrodes in the hearts, investigating patients with 'electrical' and rhythm problem. My direct boss, Prof John Camm, was , and still is in 2016 , one of the biggest names in Cardiac Electrophysiology, another growing point in cardiology.
Then, by 1986, along with the balloon, came the metallic stent, to give better result and less 'restenosis' [ re-narrowing ], from 40 % to something around 20 % and afforded the cardiologist to be more work perfect at opening arteries and more adventurous. Before the advent of 'stent', in the early days of just plain balloon angioplasty, the 1st 24 hours post procedure used to be stressful period for the interventionists as 'opened up arteries' are known to collapse and close back acutely. In lay man's term, the stent is like a scaffolding, holding back the arterial wall from closure, while it has time for self repair.
[ https://www.youtube.com/watch?v=cdSf5GOyJdw ]
With the advent of STENTS, interventionist cardiologists get braver and much much safer.
Surgical pre-consent and surgical coverage became a thing of the past.
Technique-wise the early stents were inundated still by high 're-stenosis' rate.
The expanded lesions after stenting has it's natural 'repair' process, a necessary physiological activity of the living vessel wall and a necessary one indeed.
But in 20 % of cases, this repair process did not 'know' when to stop thus 'over-repair' cause lost in the luminal gain initially achieved by the earlier procedure.
But guide wires, balloon and stent technology improve by leaps and bound over the years.
By the early 90's, DES [ drug eluting stents ] were introduced.
Growth impeding drugs such as SIROLIMUS or PACLITAXEL was impregnated into the stent. This drug, on successful implantation of the stent in the coronaries, diffuse slowly for days and weeks into the vessel wall, effecting to control cell regeneration at a more reduced level, thus reducing RESTENOSIS ie. reducing lumen loss due to excessive tissue repair.
[ https://www.youtube.com/watch?v=JeH4zPzQgRc ]
Just eight years back, another milestone was breached. Drug eluting balloon was introduced. This is a niche piece of equipment to treat increasing incidence of 'In Stent Restenosis' in patients who developed repeat narrowing within their implanted drug eluting stents.
By then angioplasty and stenting has already far outstripped in term of numbers CABG. Only the rare patients are sent for surgery.
Since people with coronary problem nowadays generally survive longer and longer due to improvement in treatment modalities as well as the massive effect of statins [ LIPITOR, ZOCOR, CRESTOR ]on lipid control, it is fairly common to see patients who developed coronary problem when they were in their early 40, having had 6 to 8 stents when they reach their mid 60's or 70's..
I myself has a lady patient of mine whom I referred for bypass surgery 15 years back, who 'chickened out' at the last minute, had 6 stents implanted then. I was earlier managing her husband whom I sent for bypass surgery 5 years earlier.
Now, 15 years later, and several episodes of 'acute coronary syndrome' and hospital admission later, she is a bionic lady with a total of 10 stents implanted by myself over the years.
This seventy five year old 'Datin' is currently still active playing and tending to her 'cucus' in a famous tea plantation in Cameron Highland. Her son is one of the senior manager there.
If you ask the 'Datin' why she opted out of her surgery and pleaded for me to do 'angioplasty, in the wee hours of 5 am , that fateful morning , her reply was simple :
" I saw how Dato' suffered during his bypass surgery and much after....Please do not force me to go thru that, Doc ! "
But to be fair to CABG, both endoluminal technique and CABG are complimentary.
The only thing that work against CABG is that while the surgeons only have their pairs of hand, over the last 40 years, the cardiologists have the whole gamut of industries helping them: the engineers, the metallugists, the whole range of bio-genetic scientists.
It is an unfair advantage!
But from my perspective , some of our patients would finally need CABG one day later in their life, only that I would like to postpone that day to as late as possible because all current techniques have their 'shelf life', and CABG is the final pathway in the life of a patient with coronary problem. It is ideally not to be repeated due to high mortality risk in repeat CABG surgery. If I can, I want to exercise other options first for my patients before the final option of CABG.
To us interventional cardiologists, coronary problem is a chronic , relentless disease. We try as hard as possible to keep all our patients from going under the surgeon's knife. Personally to me it is like playing 'gin rummy', and if you are familiar with 'gin rummy', we try to not use our precious 'jokers' early in the game. CABG is the all important JOKER! But at the same time, when we need to send our already aging patients under the surgeon's knife, we want our surgeons to be able to do his 'bypasses' at the right place. If our patient's heart are full of 'metal jackets' [ stents ], there may not be any more place for the poor surgeons to bypass.
So when BIORESORBABLE SCAFFOLD, or 'plastic stent' came into the picture about 4 years ago, most people like me cannot help but get excited. I implanted about 10 of them in my younger patients. It is a relief of sort for me since my youngest patient so far is just 22 years old. Imagine how many metal stents he would have before he reaches even 40!
These 'plastic stents' as I called them should self dissolve into carbon dioxide and water by three years. Theoretically I could re-vascularize these involved arteries and allow them to be regenerate back to normal after three years.
[ http://drnikisahak.blogspot.my/2013/08/absorb-new-absorbable-plastic-stent.html ].
This toy has now improved with the recent advent of a more durable, disappearing metallic stent, the MAGMARIS . And the possibility of 'metallic' foreign body disappearing in one year and allowing for regeneration and normal vasomotion of vessel back to its original state.....nice thought.
Now in 2016, MAGMARIS, the new magnesium stent, has just got it's CE mark. It is now open for general use and validation.. The obvious advantage over the 'plastic stent' is its relative strenght.
So far around 200 Magmaris stent have been implanted world wide, 10 of which come from Malaysia, with nine implanted by the 'boys' in IJN and one recently by me at my hospital, SJMC.
My patient is a 49 year old engineer, who developed troublesome angina on mild exertion.
Coronary angiogram done last week showed 90 % narrowing in the proximal section of the Right Coronary Artery. I implanted the Magmaris stent rightaway.
[ https://www.youtube.com/watch?v=OjwPrOgdtgQ ]
"When are you retiring Nik...and joining us for golf?.', a paediatric consultant colleague of mine who just recently retired from teaching in UH asked recently.
" I am not sure Peng, there are new 'toys' to play around with all the time....."
I am certainly living in interesting times....