Acupuncture is an effective, non-invasive modality for normalizing blood pressure, particularly systolic pressure, in people with mild to moderate hypertension. Research at UC Irvine’s Susan Samueli Center for Integrative Medicine has shown that once-weekly 30-minute sessions can lead to 15–25 mmHg systolic pressure reductions within 4 weeks, an effect comparable to that obtained with antihypertensive drug therapies. Photo: Elena Ray; Agency: Dreamstime.com.

Acupuncture can be a valuable tool for normalizing blood pressure, particularly systolic blood pressure, and it could play a much greater role in our clinical management of patients with early-stage elevations who are at cardiovascular risk, but are reluctant to accept drug therapies.

Over the last several decades, the upper level of what is considered “normal” blood pressure has been gradually decreasing. The current consensus guidelines set “normal” at 115/75 mmHg, which is much lower than what was considered normal 20 or 30 years ago. These changes are not meant to confound the public, make doctors work harder or increase consumption of antihypertensive drugs; they reflect the fact that for every increase of 20/15 mmHg over this level, the risk for cardiovascular disease approximately doubles (Joint National Commission-7 Guidelines).

Further, we also know that for people over 50, systolic pressure over 140 mmHg is much more predictive of risk than diastolic pressure. So, if a patient’s blood pressure is 120–139 mmHg systolic or 80–89 mmHg diastolic, they’re pre-hypertensive and should consider health-promoting lifestyle changes aimed at improving diet, increasing exercise and losing weight, if this is appropriate.

Searching for “Something Else”

But in the real world of clinical practice, we’re often encountering patients who find it difficult to make these changes, or who continue to have high pressure despite making real changes. Drug therapy is usually our next step, typically beginning with diuretics. But many patients eventually require two or more anti-hypertensives. And therein comes the rub.

Many don’t want to take pills every day and/or they experience uncomfortable or even dangerous side effects. Beyond frequent urination and orthostatic hypotension, their potassium levels also drop, causing arrhythmias that can become frequent or even continuous.

A lot of our patients simply want something else. They recognize that their blood pressure is too high and they agree that they need help; they just want a therapy with low or no side effects.

Acupuncture is one such strategy that has recently become the focus of significant study. Although it has been in continuous use for more than 2,000 years, and widely known to Western medicine since the early 1970s, only recently have we seen evidence suggesting its potential utility in treatment of hypertension. There are both negative and supportive studies in the literature, so the jury is still out on the real clinical value of acupuncture as an antihypertensive treatment.

But in light of some recent high-quality studies, the pendulum appears to be swinging towards acceptance of acupuncture as beneficial in normalizing blood pressure. At a recent national neuroscience conference, my colleague, Dr. Peng Li, and I presented data showing that in people with mild to moderate hypertension, two months of weekly acupuncture could reduce systolic pressure by 15–20% (Li P, Longhurst JC. J Neurosci. 2007; in press). Earlier this year, German researchers also showed substantial pressure reduction in a randomized trial of acupuncture in hypertensive people (Flachskampf FA, et al. Circulation. 2007; 115(24): 3048–3049).

To understand how this might work, it is necessary to understand something about the pathogenesis of hypertension and the neurobiologic effect of acupuncture.

Of Meridians and Millimeters

	Agency: Dreamstime.com.

Elevated blood pressure is due to either increased vascular constriction and stiffness, or to the heart pumping excess volume into the blood vessels. Diuretics and other antihypertensives typically help with the latter; acupuncture appears to help with the former. Our recent studies from the Susan Samueli Center for Integrative Medicine at the University of California, Irvine, indicate that acupuncture relaxes vessels mainly through action in the central nervous system.

At Samueli, we have done extensive animal studies looking at the neurochemical and cellular mechanisms underlying acupuncture’s effects. By putting probes into the brains of rodents, we can get precise measurements of how and where acupuncture exerts its effects. The key seems to be in modulating sympathetic outflow from the hypothalamus, midbrain, and especially the medulla. The sympathetic nervous system releases catecholamines, small molecules that can cause a profound contraction of vascular smooth muscle, hence elevating blood pressure.

Acupuncture causes release of inhibitory peptides & neurotransmitters, particularly endorphins, enkephalins, and endocannabinoids all of which quiet down activity in those area of the brain. The reduced sympathetic outflow results in vasodilation, leading to a lowering of blood pressure, particularly systolic pressure, the major blood pressure risk factor for most of our middle-aged and elderly patients.

In studying rodents, we’ve gotten down to single cell level to study how acupuncture works. Much of what we have found in the animal studies and in our clinical experience is being corroborated by Massachusetts General Hospital researchers using digital imaging to study the effects of acupuncture in the human brain. The problem is, it is difficult to image the medulla, and since we cannot easily or ethically stick probes in the brains of humans seeking acupuncture treatment, we’re quite limited in our ability to study acupuncture mechanisms in people.

Traditional Chinese medical theory has elaborate and poetic explanations for the observed effects of acupuncture involving the flow of Qi or life energy through various channels or “meridians” in the body. Over the centuries acupuncturists developed extremely detailed maps of these meridians to guide needle placement.

We use these meridian maps in our clinical treatments and our research. But we believe the key to acupuncture’s effects involves stimulation of sensory neural pathways lying directly under or in close proximity to the meridians. Nervous stimulation is absolutely critical to the acupuncture effect. In animal studies, if you cut sensory nerves and then do acupuncture, you do not see the effects.

Even traditional acupuncturists recognize this intuitively, though they use dif-ferent language to explain it. When a classically-trained acupuncturist stimulates acupoints, he or she will usually ask if you are feeling the characteristic sensations of heaviness, warmth or slight burning, and they know that if someone does not experience these sensations of the moving Qi, the treatment will not be effective.

Our studies at the Samueli Center have shown that the stimulation of acupoints along the pericardial meridian overlying the median nerves on the wrist activates small diameter sensory nerve fibers that send information to a number of regions in the brain and spinal cord.

A Role for Electroacupuncture

There are several aspects of acupuncture that separate it from simple brief stimulation of peripheral sensory nerves. The first is the concept of point specificity, which is important to consider, especially when practicing electroacupuncture, a technique that involves applying a small electrical current to the acupuncture needles.

Some acupoints can lead to strong responses, while others cause modest or no effects. Electroacupuncture applied at certain acupoints on both the pericardial meridian of the lower inner arm and wrist, and the stomach meridian lying along the front and inside region of the leg can profoundly influence blood pressure. Both meridians overlie major neural pathways, which must be stimulated to obtain a satisfactory cardiovascular response.

Slow Onset, Enduring Effect

A second important aspect of acupuncture is its slow onset and prolonged effect. In our studies of genetically hypertensive rats, we have observed that the lowering of elevated blood pressure takes between 10–15 minutes, but can last from one to 12 hours following 30 minutes of electroacupuncture. On a beat to beat basis in animal studies, we see changes within 15 minutes, leading to 40% decreases in some cases.

In humans coming to our clinic with mild to moderate hypertension (in the range of 140–170/90–110 mmHg) and who are not taking any anti-hypertensive drugs, we’ve found that once-weekly 30 minute sessions will give substantial pressure reductions of 15–25 mmHg in 2–4 weeks. If we stop the treatments, the pressure will stay down for another month or so, and then comes back up over a period of weeks. Roughly two months after cessation, it has returned to pre-treatment baselines. It is important to note that in our studies, and in others, stimulation of sham acupuncture points gives no change over the same time frame, so the responses cannot be explained away as a “white coat” effect.

In general, we’ve found that about 70% of our patients respond to acupuncture, and that seems to be a fairly constant response rate in studies from all over the world. Interestingly, we see similar response rate in animals.

Acupuncture and Antihypertensives

How does acupuncture compare to drug therapy for hypertension? Pretty well, at least in people with mild to moderate pressure elevations. For people in the 140–160 systolic range, acupuncture can get most of them down to 120–130 mmHg, which is what you want to accomplish with drugs. The difference is that instead of taking a pill every day, the patient needs only one 30-minute treatment session each week.

And compared with pharmacotherapy, acupuncture is relatively free of side effects. Occasionally, a patient will experience slight pain or dizziness, and there is a very small risk of bleeding, especially if a patient is on anticoagulant drugs. But the adverse effect profile is very favorable compared with drugs like the ACE inhibitors that frequently cause intolerable coughing, kidney problems and problematic hypotension. For mild to moderate pressure elevations, acupuncture can be a reasonable substitute for pharmacotherapy, or at least represents a good therapeutic starting point.

In our clinic, we don’t treat severe hypertension with acupuncture. You’re not likely to bring a patient with systolic pressures over 200 mmHg down to healthy range with acupuncture alone. If you need to induce a big drop, drugs are the best choice.

However, one of our hopes for the future is that for patients with severe hypertension, we might be able to use acupuncture as a reinforcing, adjunctive treatment after a few months of drug therapy. We may be able to lower the medication doses. Other researchers have suggested a dose-sparing effect, and we’re just starting to study that possibility at our clinic.

The ideal candidate is a patient with relatively mild hypertension who has not yet been on antihypertensive drugs. However, we can treat those on medications, provided we’re careful. If a patient is on anticoagulants, they may have a bit of bleeding, but it is generally not problematic. Modern acupuncture uses 32–37 gauge needles, which are about 20 times thinner than the typical hypodermic needle. So if hypodermics are not contraindicated in patients on anticoagulants, acupuncture needles should not be.

A Normalizing Effect

Another important thing to understand about acupuncture is that unlike pharmaceuticals, its effect can be bi-directional or even non-existent, depending on the individual patient’s condition. For example, subjects with normal blood pressures tend to show little change in pressure following acupuncture. Give an antihypertensive medication to a normotensive person, and you’ll still see a pressure drop.

There’s also some experimental evidence to suggest that if blood pressure is low, as in cases where it is decreased by a reflex that lowers heart rate and blood pressure, acupuncture may be able to elevate it.

This is because in addition to its effects on the sympathetic branch of the nervous system, it can also be used to inhibit the parasympathetic system. When parasympathetic nerves are activated, heart rate and heart function are decreased to lower cardiac output and reduce blood pressure. Acupuncture may be able to inhibit parasympathetic function, ultimately raising blood pressure.

This is a new area of acupuncture research, and we’re just starting to explore it. There’s enough data out there to suggest that acupuncture can raise blood pressure. I’ve seen it in our lab and I believe it.

Rather than thinking of acupuncture simply as an “antihypertensive” treatment, it is more accurate to think of it as a pressure normalizing treatment, one that can be used to influence the balance between sympathetic and parasympathetic nervous function. It can lower pressure when it is elevated or raise pressure when it is too low. And unlike pharmacotherapy, it has no significant effect when baseline pressures are within the normal, healthy range.

Studies examining all of these different aspects of acupuncture are still in their infancy. However, early clues from our experience at the Samueli Center suggest that because acupuncture has few and very minor side effects, it has the potential to become an important part of our strategies for managing patients with hypertension and high cardiovascular risk.

Ongoing studies at our center (www.sscim.uci.edu) and others across the country will continue to define the role of acupuncture in treatment of hypertension and other common cardiovascular problems.

If you are considering acupuncture for your patients with mild to moderate hypertension, make sure you’re referring them to well-trained, licensed (or license-eligible) acupuncturists. Currently 35 states have licensure for graduates of recognized training programs. Even in states without licensure, there may be license-eligible practitioners to whom you can refer.

The Consortium of Academic Health Centers for Integrative Medicine is a valuable resource for finding qualified practitioners in your area. Visit www.imconsortium.org, or email Jeannie Schwartz, program coordinator at cahcim@umn.edu. If you are in Southern California, consider sending your patients to the Samueli Center’s integrative clinic, where we have several very well trained acupuncturists with experience treating cardiovascular risk.

Dr. John C. Longhurst is Professor of Medicine, Physiology and Biophysics at the University of California, Irvine, and Director of the Susan Samueli Center for Integrative Medicine, which is dedicated to advancing patient care through education, research and applied integrative medical therapies. Dr. Longhurst also holds two endowed chairs, the Susan Samueli Chair in Integrative Medicine and the Lawrence K. Dodge Chair in Integrative Biology, and is Professor and Associate Dean for Programs and Development at the University of California, Irvine.

Translating Chinese Medicine

“I went into this kicking and screaming,” says Dr. John C. Longhurst, of his pioneering research on the cardiovascular effects of acupuncture.

Back in 1994, Dr. Longhurst was Chief of Cardiology at University of California, Davis. A dyed-in-the-wool reductionist researching the neurobiology of cardiovascular regulation, he had little taste for the New Age flavors of the holistic medical movement.

When he received a request from Dr. Peng Li, a physiologist at the University of Shanghai, seeking his expertise in developing a study of acupuncture and the heart, his initial response was unequivocally negative. “I said no, flat out. I simply did not believe in acupuncture. But then Dr. Li gave me his CV. He had very good scientific credentials, and he was publishing in some really good journals. I figured that I had better reconsider.”

Dr. Longhurst visited Dr. Li in China, where he had ample opportunity to see acupuncture in action. It changed his mind, and his life. He came home convinced that acupuncture produces real physiological effects that warranted serious clinical research. He invited Dr. Li to come to California for a sabbatical, and the latter ultimately emigrated along with his family.

Drs. Li and Longhurst now work together at the Susan Samueli Center for Integrative Medicine at UC Irvine, and have been at the forefront of American acupuncture research. It turns out that Dr. Longhurst’s thorough knowledge of how the central nervous system controls heart function was an ideal background for a serious scientific exploration of acupuncture.

“We try to translate between Traditional Chinese Medicine theory and modern allopathic biological language,” Dr. Longhurst told Holistic Primary Care. “There’s only about a 50% acceptance rate of acupuncture among conventional Western MDs. Part of that is that they don’t understand the terminology of TCM. So we’re trying to translate it for them.”

At the Samueli Center’s clinic, Dr. Longhurst and his colleagues use the meridian maps developed over centuries by TCM practitioners, but they explain what’s happening in the language of neurobiology, rather than descriptions of Qi flow. “The “flow” through the meridians really has to do with neural impulses. The meridians are really just maps. There’s nothing anatomical about the meridian points that you can measure on the skin surface. But they are maps of how to stimulate the sensory nerve fibers.”

In many ways, the Samueli Center’s application of acupuncture is a departure from classic TCM theory, something Dr. Longhurst readily acknowledges. “We’re an academic research center, not a TCM school, so our approach is different.” But their work is validating many of the phenomena posited by China’s ancient medical sages.

Along the way, Dr. Longhurst has become an important contributor in the effort to develop valid methodologies for acupuncture research. His diligence has won the Samueli Center two major five-year grants from the National Heart, Lung, and Blood Institute to study the effects of acupuncture on the cardiovascular system.

He is hoping that in a few years, the data supporting use of acupuncture to reduce heart disease risk will be as strong as it now is for acupuncture and chronic pain problems.

Dr. Longhurst himself has come a long way in his journey from naysayer to national expert. The decisive influence was simple open-minded observation, which should be the hallmark of science. “I saw it work in China, and I saw it work in my own labs. I would say my belief system definitely underwent some changes!”