New Procedure Deactivates Overactive Nerves In The Kidneys And May Aid Stubborn High Blood Pressure

Robert just could not get his blood pressure under 180/140. First his doctor put him on common antihypertensive medication called propanolol. This beta-blocker slows down nerve stimulation to the heart and usually lowers blood pressure quickly, but Robert's blood pressure didn't budge.

Next Robert pulled off the impossible and managed to lose 72 pounds (about 33 kilos). This didn't help, either.

Robert's doctor put him on a second drug called lisinopril. This medication is perhaps the best known medication of a class known as angiotensin converting enzyme (ACE) inhibitors. These medications prevent the activation of an enzyme that makes the kidneys retain fluid to maintain blood pressure (which is a good thing during blood loss but not a good thing under ordinary circumstances). The doctor also put Robert on a medication called Imdur, sold under the generic name isosorbide mononitrate. This medication acts in a way similar to the "nitro" pills some people take for chest pain. It helps the linings of blood vessels relax to lower the pressure of the blood within them.

Then Robert managed to master a yoga discipline called pranayama breathing. He felt better, but his blood pressure did not go down.

One, Two, Even Three Drugs Together May Not Be Enough to Control Blood Pressure

The three drugs brought Robert's blood pressure down to 175/138. The doctor doubled the dosage, and added a fourth drug called Ranexa (ranolazine). This pricey medication changes the way heart and brain tissue respond to sodium, keeping them from "powering down" by absorbing too much sodium, sugar, and fluid. Ranexa helps the heart beat evenly.

That got Robert's blood pressure down to 160/130. Unfortunately, that is still a dangerously high blood pressure. The doctor then prescribed yet another medication called ticagrelor, which is sold in the United States under the trade name Brilinta. This drug stops the process of inflammation that can tighten blood vessels and increase blood pressure. The doctor would have put Robert on a medication called losartan, a drug that stops the kidneys from responding to the hormone angiotensin (an ACE-receptor blocker), but it would conflict with the Brilinta. The doctor also gave Robert nitroglycerin pills to put under his tongue when his chest hurt.

Even that was not enough, so the doctors put Robert in the hospital and gave him the same drugs in an IV. That intervention worked, bringing Robert's blood pressure to 90/60, as long as he stayed perfectly still in a hospital bed breathing oxygen through a face mask. There were still more medications to be tried, including aldosterone and spironolactone, but these drugs cause men to accumulate female hormones. There had to be a better way.

A Surgical Alternative to High Blood Pressure Drugs

Fortunately for Robert, there was a surgical alternative to all the high blood pressure medications that don't work, a relatively new procedure called renal denervation. This relatively new procedure has been used for several years in the UK and European Union to treat resistant hypertension. And unlike many other procedures for cardiovascular problems, renal denervation is not an especially traumatic procedure.

What Is Renal Denervation?

Renal denervation is surgical procedure that deadens nerves that make the kidneys retain sodium instead of filtering it out into the urine. Since the concentration of sodium in the bloodstream has to be kept constant, the kidneys release water to increase low sodium levels, increasing blood pressure, or they retain water to decrease high sodium levels, lowering blood pressure. The concentration of sodium in the bloodstream has to kept constant so that nerve cells will fire normally.

In times of stress, however, the fight-or-flight nerves of the sympathetic nervous system require extra sodium, that is a greater total amount of sodium, but not a higher concentration of sodium (which would disrupt other processes in the body).

They send a signal to the kidneys retain sodium for them, but when the kidneys retain sodium, they also have to retain fluid. The extra fluid fills blood vessels and raises blood pressure. In about 1 in 11 people who have hypertension, the nervous system "switch" that regulates sodium retention and blood pressure gets "stuck," and medications for blood pressure just don't work.

People who have resistant hypertension typically have persistent reactions to emotional stress. It doesn't do any good to "train the brain" to relax, however, because the sympathetic nerves are stuck in the fight-or-flight pattern. Just about the only thing that will lower resistant hypertension is surgical denervation.

The Surgical Procedure for Renal Denervation

Advances in surgical technique have made renal denervation surgery almost painless with a very fast recovery time. The surgeon applies a topical anesthetic to the skin of the groin, and opens a 3 mm-wide incision into the femoral artery. (Even if the anesthetic did not work, the incision is not especially painful, as the writer knows from personal experience.) 

The surgeon threads a tiny pipe, or catheter, through the femoral artery to the kidneys, where a radio transmitter is used to kill nerve fibers with quick bursts of high-energy radio waves. In the European Union but not in the United States, some surgeons squirt the nerves with methanol (wood alcohol) to make sure they are destroyed, but this is not permitted in the USA.

Then the surgeon removes the catheter and closes the incision. The incision is closed with a glue-like dressing and sutures that dissolve on their own. The patient simply loosens the packing of the wound in the shower 2 or 3 days later, and recovery is complete.

Does Renal Denervation Really Work?

A study of renal denervation at the Baker IDI Diabetes and Heart Research Institute in Melbourne, Australia found that the average blood pressure of 106 patients who had the procedure fell from 176/97 to 143/85 in the six months after the surgery. A control group of patients who did not have surgery actually had higher blood pressures after six months of standard treatment with multiple medications. A blood pressure of 143.85 isn't "good," but it is far less dangerous than a blood pressure of 180/100 or more.

The few patients who run into trouble after renal denervation surgery are those who do not follow instructions in the recovery room. For about two hours after the surgery, it is imperative to lie still so the surgical dressing stays packed on the femoral artery. If the patient sits up, gets up to go the bathroom, or pulls at the dressing, serious bleeding can result. 

The procedure itself is problem-free about 95% of the time. It's always possible for a surgeon to nick the wall of an artery, causing bleeding, and sometimes the procedure works too well, and causes seriously low blood pressure. To date, however, no one has died or suffered lasting injury as the result of renal denervation.

Renal denervation surgery has been used successfully in treating thin patients, obese patients, older patients, younger patients, patients who have diabetes and patients who do not. To find out whether it might work for you, especially if you are a thin person who exercises and still has high blood pressure, consult your physician.