Every morning, I clip it onto my belt, or tuck it into a hip pocket. I very carefully attach its sticky little electrode pads onto the skin just over my heart, tucking their long black wires under my clothing. Lately, I also have to hold the electrodes in place on my skin with surgical tape because they’re starting to lose their stickiness after so much daily wear. I turn on the black box at my waist, and adjust its two knobs to the correct power levels. I feel a prickly little buzz pulsating across my chest.
It’s called Transcutaneous Electrical Nerve Stimulation (TENS), and it involves electrical impulses called neuromodulation to treat the chest pain (angina) of Inoperable Coronary Microvascular Disease (MVD).
My portable TENS unit is about the size of a small cell phone. You may know the much larger version of this machine if you’ve ever had physiotherapy treatments following a muscle injury. The only wounded muscles it’s working on for me now, however, are those in my heart. Emerging cardiac research is showing that, just as the TENS machine works on improving blood flow, reducing inflammation and speeding up healing for an injured shoulder or knee, it may bring the same benefits to heart patients with MVD like mine.
But I do have a love-hate relationship with my little black box.
I was told by my cardiologist that research suggests significant success using TENS neuromodulation to treat the debilitating chest pain of angina. Since 2001, the U.K. National Refractory Angina Centre has in fact recommended TENS therapy for persistent angina in heart patients:
“Neuromodulation owes its origins to Melzack and Wall’s gate theory of pain that predicted that stimulation of vibratory afferent nerves would reduce or gate the transmission of pain traffic relaying through the spinal cord at the same point.
“Transcutaneous electrical nerve stimulation (TENS) was specifically designed to make use of this predicted effect and was used to treat a variety of pain conditions before it was shown to be effective in angina.
“Neuromodulation should be offered as part of a multidisciplinary angina management programme based on the current guidelines.“
My cardiologist prescribed a TENS unit to relieve refractory angina – mysteriously ongoing chest pain that does not respond to conventional drug therapy – since my heart attack. It cost about $120, a tax deductible medical expense here in Canada. His initial directions: turn it on twice a day, 30 minutes at a time.
New drugs and then more new drugs had not helped relieve these distressing and debilitating angina symptoms at all. Even a second admission to the hospital’s cardiac unit for another invasive procedure showed no new coronary artery blockages – a relief for those of us with stainless steel stents implanted inside our coronary arteries.
But those results also felt to me like ‘good news, bad news’.
The good news: my symptoms were not due to stent failure.
The bad news: my symptoms were not due to stent failure.
Had this ongoing chest pain been due to a good ol’ garden variety blockage within the stent or another major coronary artery, cardiologists may have been able to identify and address that.
But now what?
The new diagnosis emerged: Inoperable Coronary Microvascular Disease (MVD) involving the very smallest of the coronary arteries. It’s a painfully debilitating condition, usually missed using conventional cardiac diagnostic tools – and thus difficult to diagnose appropriately. UPDATE: Although previously considered to be more often seen in women, studies now suggest that both men and women are affected equally by MVD.
My revised diagnosis of MVD also prompted a referral to the Regional Pain Clinic at our local hospital, and my first meeting with my new pain specialist, a charming pharmacist-turned-family doctor-turned anaesthesiologist, who is (just my luck!) an internationally-known expert on intractable pain management in heart patients.
In fact, he had spent a year on a medical fellowship in Sweden studying this particular treatment for MVD. Just as in the U.K. and elsewhere, neuromodulation therapy in Sweden is widely recommended because it’s an effective, non-drug, non-invasive option to treat Inoperable Coronary Microvascular Disease and refractory angina.
These are diagnoses for which our conventional “revascularization” cardiac procedures like stents or bypass surgery provide no benefit.
My pain specialist prescribed a stepped-up one-month trial wearing my TENS unit every day, all day long instead of just for two 30-minute periods per day.
After a successful month of this revised routine (amazingly, with significantly reduced need for my nitro to address chest pain), he pronounced that I might also make an excellent candidate for an invasive surgical procedure called a Spinal Cord Stimulator Implant (SCSI). Neurostimulation like this is sometimes used in patients with angina when other therapies have failed. It’s has been shown to increase coronary blood flow, to reduce the duration and frequency of anginal attacks, and to reverse ST-segment depression during stress testing.(1)
At the Pain Clinic, I listened to my pain specialist’s carefully detailed explanation of the SCSI procedure to manage chest pain.
But ultimately, I decided that any invasive surgical treatment beginning with the words “spinal cord” seemed too overwhelming for me to contemplate at this time, especially when my little portable TENS unit seems to be doing the trick for now.
Another effective therapy sometimes used to temporarily treat the pain of Inoperable Coronary Microvascular Disease is a nerve block procedure called a stellate ganglion block (SGB).
My pain specialist explained to me that this involves an injection of local anesthetic to block the sympathetic nerves located in the neck. An injection at these nerves may reduce pain symptoms of intractable angina for a period of up to four months. SGB is also used to see if blood flow can be improved in those patients with circulation problems that are related to vascular disease. This procedure is already in widespread use in a variety of chronic pain conditions, and also has a history of use in the management of angina. (2)
Instead of either of these options for the time being, I’ll continue to have my progress with my little black box monitored at ongoing follow-up visits to the Pain Clinic.
My pain specialist assured me (and then produced copies of medical journal articles* to further explain) that the electrical current produced by both my little black box and by the Spinal Cord Stimulator Implant actually in itself produces some remarkable therapeutic effects on heart function.
Although he also told me that, unfortunately, “very few” of his Pain Clinic referrals are heart patients like me, we know that electricity to treat all types of pain has been used as far back as 63 A.D. Back then, it was reported by Scribonius Largus that leg muscle pain could be relieved by standing on an electrical eel at the seashore.
Electricity to treat cardiac pain works by modifying the neurologic input and output of the heart by delivering a very low-dose electrical current. This causes neural fibres to then release something called peptides into the coronary blood flow that actually reduce the heart muscle’s demand for oxygen. In addition, peptides can help to widen those small blood vessels of the heart (vasodilation) that in turn improves blood flow to the most diseased region of heart muscle.
So my little black box works not just by offering me 12+ hours of reasonable relief from debilitating daily chest pain, but it also seems to be actually helping open up those microvascular coronary arteries.
My need to take nitroglycerin these days for chest pain, for example, is significantly reduced – something that I had previously needed sometimes 3-4 times during a “bad day” to control debilitating – and terrifying – chest pain. We had considered nitro patches or long-acting nitro pills, but because my angina pain was wildly episodic, the TENS unit looked like a win-win option.
But along with this development, I discovered in the very early days a new kind of debilitating experience until I learned how to manage it. As I told my doctor:
“Wearing this TENS unit is like having somebody standing on my foot all day long.”
It wasn’t particularly painful, but the distraction factor could drive you stark raving mad. I asked him how much of my newfound pain relief was due to the therapeutic effectiveness of the TENS electrical m, and how much just to the extreme distraction of the current buzzing across my chest every few seconds, hour after hour, all day long.
I found, for example, that until I got used to it, this distraction made it difficult to drive while the TENS was turned on. My early morning walks had me stopping every 10 steps to clutch my chest, all the while assuring my alarmed walking buddies that I wasn’t having another heart attack, but I was merely trying to get used to the electrical fireworks going on inside my body. Even conversations were difficult at first, as every few seconds I felt compelled to s-l-o-w down and focus on the fireworks instead of on what others were saying.
The good news, delivered during my last visit to the Pain Clinic, was that I’m now allowed to turn the dial down – way down! – to an almost imperceptible electrical buzz.
My pain specialist explained to me that recent research has shown similar cardiac benefits using extremely low levels of electrical simulation compared to my annoyingly distracting higher levels. He told me of one of his heart patient who had turned his TENS unit settings up so high that his pecs could be seen dancing and pulsating through his shirt – a flawed assumption that ‘if a little is good, then more is better’.
These days, I’m finally getting used to strapping on my little black box every morning as part of a normal routine.
This week, I’ve even replaced the annoyingly itchy surgical tape with several strips of a new hypo-allergenic paper tape which don’t cause nearly as much skin irritation. But they also don’t stick as well, unfortunately, particularly in hot weather, which has caused quite a few embarrassing public incidents this past summer involving my newly-freed electrodes flapping in the breeze around my knees.
As my pain specialist explains, the small but mighty TENS unit is actually helping my coronary arteries bear their workload in spite of Inoperable Coronary Microvascular Disease.
I certainly don’t want to return to those terrifying bouts of chest pain and subsequent nitroglycerin dependence – so I’ll continue my attempts to embrace this little miracle device riding on my hip.
Although I may give in occasionally to whining and wimping about wearing my little black box, I’m also gobsmacked that more heart patients are not being offered this treatment option.
Why aren’t more patients offered this non-drug, non-invasive, inexpensive and effective therapy for the debilitating symptoms of chronic angina?
When I recently asked another MVD patient suffering with refractory angina if she had asked her own cardiologist about using this particular pain management option, her shocking response to me was:
“I had mentioned this to my cardiologist and he wanted nothing to do with it ( ‘…not his field’).”
“Not his field”? If addressing crushingly debilitating angina pain in his heart patients is “not his field”, what on earth is?
♥ ♥ ♥
TENS UPDATE, November 29, 2011: At today’s regular follow-up appointment at the Pain Clinic, my pain specialist added two simple recommendations for all heart patients wearing portable TENS units:
1. Replace the sticky pads on your TENS every 6-8 weeks if you, like me, are wearing your TENS from morning to night, seven days a week. In between replacement, follow the device instructions for regularly cleaning the sticky pads (I use a soft baby toothbrush for this).
2. Change the internal setting on your TENS from ‘modulate’ to ‘constant’ and vice versa (some reports suggest that this little adjustment can mean improved pain management results).
♥ You can watch videos of the 2019 INOCA International “Meeting of the Minds” microvascular disease conference keynote speakers in London, including Dr. Juan-Carlos Kaski’s presentation.
UPDATE November 2019: Diagnostic tools used to identify coronary microvascular dysfunction
(1) Mehta PK, Bairey Merz CN. Treatment of stable angina in subjects with evidence of myocardial ischemia and no obstructive coronary artery disease. In: Bonow RO, Mann DL, Zipe DP, Libby P, editors. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia: Saunders/Elsevier; 2008.
(2) “Influence of Stellate Ganglion Blockade on Angina Pectoris and the Post Exercise Electrocardiogram”, Moore DC. Stellate ganglion block. Springfield, IL: CC Thomas, 1954; Wiener L, Cox JW. American Journal of Medical Science, 1966;252:289-295
* The medical journal articles shared by our Regional Pain Clinic are: