External Counterpulsation -- A New Paradigm for Treating Heart Disease
External Counterpulsation (ECP) is an ingenious method for treating angina that doesn't use drugs, is non-invasive, inexpensive and safe -- unlike conventional surgical procedures such as angioplasty and bypass surgery. Physicians should
inform patients of all the treatment options available for ischemic heart disease, including FDA-approved ECP, says physician Dr. Grossman.
Published on KurzweilAI.net June 17, 2002.
Cardiovascular disease is the leading cause of death in the U.S.,
according to CDC statistics.1 Conventional treatment
options typically include lifestyle modification, prescription drugs
and surgery. While often effective at relieving symptoms such as
chest pain or angina, these therapies have several drawbacks. They
are frequently ineffective at extending life, are associated with
numerous side effects and complications, and are expensive. Heart
surgery carries a significant risk of death, and often leads to
other morbid events.
In addition, a significant number of successfully treated patients
become "treatment failures" over time. Following bypass
surgery, it is estimated that only 75% of patients remain free of
cardiac ischemia for five years, a figure that drops to 50% by ten
years.2
Most new medical advances for treating heart disease are, for the
most part, extensions of two existing therapies: prescription drugs
and invasive surgical procedures. Any new therapy that could impact
the leading cause of death in this country would represent a major
advancement in anti-aging therapeutics. There is currently such
a therapy, which is an entirely new paradigm for treating heart
disease.3 This procedure is called either External Counterpulsation
(ECP)4 or Enhanced External Counterpulsation (EECP)5
and has recently received FDA approval for treatment for ischemic
heart disease.6
In development for almost 50 years, ECP is an ingenious method
for treating angina that does not use drugs and is completely non-invasive.7
For the first time since the advent of bypass surgery, a unique
therapeutic dimension has emerged for the treatment of patients
with ischemic heart disease.8
The History of Counterpulsation
[Counterpulsation9]
Kantrowitz and Kantrowitz were the first to describe the principle
of "phase shift" diastolic augmentation in the 1950's.
Ten years later, Jacobey et al. provided the first evidence that
counterpulsation could enhance the development of coronary collateral
circulation. They suggested that counterpulsation might have value
in the treatment of patients with coronary insufficiency and angina.
At the same time, Birtwell and Clause working at Harvard developed
the Intra-aortic Balloon Pump to help support blood circulation
during cardiac surgery and in cases of cardiogenic shock.10
In 1983, Zheng and associates at Sun Yat Sen University in China
designed a sequenced pneumatic external counterpulsation system,
which produced excellent results in cases of coronary insufficiency.11
Long-term relief from symptoms of chronic angina were noted. These
favorable results led a number of scientists in the U.S. to begin
research into external counterpulsation. In 1995 an American company
began importing the Chinese device following FDA market approval.
Mechanism of Action
Though a non-invasive device itself, we see that external counterpulsation
had its origins in a very invasive device, the intra-aortic balloon
pump. ECP has a similar mechanism to the intra-aortic balloon pump,
but works on the outside of the body. A modern day ECP unit consists
of a computer microprocessor, which triggers the sequential inflation
with compressed air of cuffs that are wrapped around a patient's
calves, thighs and buttocks. Compression is triggered to occur during
diastole (the resting phase of the heart rhythm). As the computer
inflates the cuffs, blood is propelled from the lower body back
into the heart. At the end of diastole, the ECP computer signals
the sudden and simultaneous deflation of the cuffs, greatly reducing
vascular resistance and assisting the heart with its next beat.
This action also facilitates venous return of blood into the heart,
increasing cardiac output.
ECP improves blood flow to the coronary arteries and helps treat
angina, the indication for which it has received FDA approval. Most
researchers feel that ECP helps angina by causing the release of
a hormone known as vascular endothelial growth factor (VEGF). As
ECP causes the heart to receive an unexpected surge of blood during
diastole (when it is normally emptying), VEGF levels increase dramatically.
VEGF promotes the development of collateral coronary vessels.12
In other words, ECP causes the heart to grow its own bypasses.
For the past few years, doctors at The Texas Heart Institute have
been involved in gene-therapy research, trying to develop an injectible
form of VEGF as well.13
The Need for ECP
ECP fills a critical need because an increasing number of patients
with refractory angina are either unwilling or unable to undergo
invasive revascularization surgery. Many patients who have undergone
bypass surgery are reluctant to undergo repeat surgery after their
first (or even second) bypass has begun to fail. Additionally, thanks
to better lifestyle choices, aggressive cardiac rehabilitation programs,
and conventional medical and surgical therapies, many patients with
cardiovascular disease are now living much longer lives. Many now
live long enough that they reach a point where invasive therapies
become too dangerous and/or medications are no longer effective.
Yet, the dilemma is that improving the quality of life with medication
and surgery in elderly patients is more difficult due to the higher
incidence of adverse side effects. For example, Taddei found that
for every ten-year increase in age, the risk of death for patients
undergoing balloon angioplasty increases 65%.14 Alexander
found that octogenarians undergoing coronary artery bypass grafting
had a 270% increase in mortality compared to younger patients and
twice the incidence of postoperative stroke and renal failure.15
In addition to age, other reasons that often preclude angina patients
from pursuing further treatment with drugs or surgery include: unavailability
of grafts, comorbid situations such as diabetes or congestive heart
failure, adverse coronary anatomy, and intolerance or ineffectiveness
of medications. ECP is an excellent option for such patients and
has been shown in numerous studies to be effective in cases where
coronary angioplasty or bypass surgery has failed.16,17
Today's patients are better educated about their diseases. They
are more aware of treatment options and consequently seek safer
and less invasive treatments. They understand that surgical procedures
such as stent placement, angioplasty and bypass surgery are not
free of risk. Even the newest surgical treatments, such as transmyocardial
laser (where a laser beam is used to drill tiny holes in the wall
of the heart), suffer the same drawbacks as their predecessors,
being invasive, expensive, and associated with a high rate of complications.18
Advantages and Safety of ECP
A recent study of external counterpulsation involving patients
from seven university hospitals, on the other hand, showed that
ECP was both effective and without risk of serious side effects.
(The only reported side effect to date from ECP is chaffing of the
skin on the legs.) It was the conclusion of this study that "Enhanced
external counterpulsation reduces angina and extends time to exercise-induced
ischemia in patients with symptomatic coronary artery disease. Treatment
was relatively well tolerated and free of limiting side effects
in most patients."19
ECP patients typically undergo one hour of treatment daily, five
days a week for seven weeks. In more advanced cases of ischemic
heart disease, such as severe triple vessel disease, it is not uncommon
for additional ECP treatments to be needed.20
The Modern Bias Towards Invasive Procedures
However, ECP is a non-invasive procedure, while the current bias
in conventional cardiology favors invasive therapies. Topol recently
described the prevailing preoccupation of using surgery to open
coronary arteries as nothing more than "coronary cosmetology."21
This bias towards surgical therapies is difficult to understand
when one considers that a procedure such as angioplasty, done over
500,000 times annually in the U.S., does not have the support of
studies that prove that this procedure decreases the risk of heart
attacks and death.22,23 Indeed, two major studies that
compared angioplasty with medical therapies both showed angioplasties
to be ineffective in preventing myocardial infarction and death.
, A recent meta-analysis that compared angioplasty to medical treatment
for non-acute coronary heart disease found angioplasty of value
in reducing angina, but only at the cost of significantly increased
rates of myocardial infarction, need for coronary artery bypass
graft surgery and repeat angioplasties.24
The New Concept of Vulnerable Plaque-- Have We Been Operating
on the Wrong Lesions?
Cardiologists and cardiac surgeons typically operate on "high
grade" occlusions of the coronary arteries (70-100% occlusions),
while ignoring lower grade lesions. Yet, heart attacks are most
commonly due to rupture of atherosclerotic plaque that occludes
less than 50% of the vessel. Rupture of a 90% lesion with subsequent
heart attack is much less common.25 Yet it is the 90%
lesion that gets the angioplasty, while the more dangerous 10-50%
lesions are ignored. The new concept of "vulnerable" atherosclerotic
plaque posits that the smaller deposits of cholesterol along the
walls of the arteries are far more dangerous than their larger,
older and more obstructive cousins. The smaller lesions tend to
be softer and more "vulnerable" to rupture upon exposure
to free radicals, with subsequent heart attack or stroke.26
Due to the high failure rate of angioplasty alone, cardiologists
have turned to angioplasty with stent placement. Stents (tubes made
out of wire mesh that are inserted into arteries to help keep them
open) did not come into wide use until 1995, so studies regarding
their long-term effects do not exist. However, a recent study suggests
that stents cause inflammation of the walls of arteries that "may
have implications with respect to the progression of atherosclerosis
in coronary arteries."27 Interestingly, this lack
of long-term research on stents has not decreased their use, and
stent placement has grown over the past few years into a multibillion-dollar
industry.28
The statistics for bypass surgery are sobering as well.29,30
The 22-year VA follow up study of coronary artery bypass surgery
for stable angina found that patients who underwent bypass surgery
experienced neither long-term survival or symptomatic benefit.31,32
It has been estimated that up to 44% of bypass surgeries are done
unnecessarily or for equivocal reasons.33 Graboys found
that, when second opinions were obtained prior to coronary artery
bypass surgery, as many as 50% of the surgeries could be safely
deferred or postponed indefinitely.34
One of the easiest determinants of cardiac function is measurement
of the "ejection fraction," the percentage of blood contained
within the left ventricle that is pumped out with each heartbeat.
Bypass surgery has been shown to be the most beneficial to those
angina patients with an ejection fraction of less than 50%. For
patients with an ejection fraction over 50%, there appears to be
no benefit, yet the majority of patients undergoing bypass surgery
have ejection fractions greater than 50%.
Primum non nocere - "First of all, do no harm"
Throughout their training, medical students are cautioned again
and again: Primum non nocere -- "first of all, do no
harm." This cardinal rule of medicine dates back to the days
of Hippocrates35 and Galen. With regard to coronary artery
disease, this fundamental principle would seem to dictate that physicians
should look first to treatments that are safe, simple and affordable
before proceeding with others that are dangerous, painful and costly.
Perhaps residency programs train cardiologists to focus on invasive
procedures, leading to patients not being adequately screened prior
to undergoing angioplasty and surgery.36
There is ample evidence of bias towards more dangerous and invasive
therapies as first-line treatments for angina. One of my former
professors from medical school and an excellent cardiologist, Dr.
Richard Conti, exemplifies this bias as he notes that external counterpulsation
has great potential, but should not be first line therapy.
He encourages physicians to aggressively pursue revascularization
therapies first.37
ECP is recognized among many cardiology experts as a valid treatment,
and many cardiology groups around the country have ECP machines
in their offices. But the prevailing sentiment is that ECP should
be reserved for those patients who are not candidates for invasive
therapy or for cases where such surgery has been done and subsequently
failed. If ECP is safe and effective in cases where pharmacological
and surgical revascularization has failed, imagine its potential
in treating patients with less advanced or severe ischemic heart
disease.
Involving Patients in Treatment Decisions
Primum non nocere, first of all, do no harm -- the role
of physicians is to foster informed participation and allow patients
to become actively involved in the treatment decisions. Current
trends in medicine are away from paternalistic informed consent
and towards informed decision-making, which emphasizes meaningful
dialogue between the patient and physician.38 Patients
who are truly informed and take part in their treatment decisions
are more likely to be compliant. Let physicians inform patients
of all the treatment options available for ischemic heart disease.
Lifestyle modifications such as diet, exercise, and stress management
should be tried first. Then if additional therapy is needed, present
the full spectrum of approved treatment options: prescription medications,
angioplasties, stents, bypass surgery and ECP, and let the
patient decide. ECP should not be treated as an ugly stepchild selected
only as a last resort.
Some might argue that in cases of angina, the stakes are too high
and there is no room to allow patients their choice of treatment.
Nease et al recently studied this issue of patient attitudes toward
treating their chronic angina.39 Considerable variability
was found in patients' willingness to tolerate anginal symptoms.
The researchers concluded that management of ischemic heart disease
should not be based on the strict use of practice guidelines or
the severity of symptoms alone, but rather should take into account
the feelings and preferences of the patient.
Conclusion
While ECP is not a panacea and is not suitable for all patients,
there are many patients who could benefit from this safe and novel
treatment and would indeed request it, if only they were informed
that it was available. When physicians discuss treatment options
for angina patients, they need to provide balanced presentations
and include full explanations of the pros and cons of all available
alternative therapies, not just the pros of one therapy and the
cons of another.
The optimal treatment plan should take into account the best available
scientific data as well as the preferences of the individual patient
in a shared decision-making process. The time has come to include
discussion of ECP with cardiac patients as a safe, painless, inexpensive
alternative to invasive therapy.
Terry Grossman M.D., M.D. (H), N.M.D, has offices in the Denver
CO area and can be reached at terry@liv4evr.com.
His office phone is toll-free 877-548-4387.
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Copyright © 2002 by Terry Grossman. Used with permission.
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