Renal denervation for moderate and severe resistant hypertension

Interventional cardiologists and nephrology hypertension specialists at Penn Medicine have introduced percutaneous renal denervation (RDN) as an option for patients with refractory hypertension.

Renal nerves and resistant hypertension

Heightened activity in the renal nerves is known to contribute to hypertension and its perpetuation by elevating sodium retention and secretion of renin, a hormone involved in blood pressure (BP) regulation, fluid balance, and vasoconstriction. Other effects include water retention and reductions in renal blood flow and glomerular filtration rate.

Resistant hypertension is defined as sustained elevated blood pressures (>130/80 mm Hg) that remain unresponsive to at least three drugs (including a diuretic) used at maximally tolerated doses. Intensifying further medical treatment in this already heavily medicated population is challenging.

Hypertension specialists have long sought alternative treatments to reduce heart disease, stroke, kidney damage, vision loss, and other long-term effects of uncontrolled high BP.

RDN: A safer means to disrupt renal nervous activity

RDN is a catheter-based therapy that targets and ablates the sympathetic nerve bundles in the renal arteries.

The precedent for RDN was a surgical procedure developed in the 1930s, renal sympathectomy, which was abandoned for its high morbidity, serious adverse effects, and long-term complications. With the later advent of percutaneous surgery, the impetus for a safer means to disrupt renal nervous activity evolved.

RDN works by advancing a catheter from the femoral artery into the renal arteries. Once in place, a probe is advanced from the catheter to deliver either radiofrequency or ultrasound energy (depending upon the system used) through the lumen of the artery to ablate the surrounding renal sympathetic nerves.

More recent clinical trials involving the currently available devices offer long-term data out to three years that demonstrate maintenance of blood pressure reduction with incremental lowering of blood pressure over time, with some studies showing 17 to 20 millimeter reductions in systolic blood pressure as well as excellent safety data.

Caveats

At this time, it is unknown which patients respond best to renal denervation.

It is known that approximately 20% of patients will not respond to the therapy, and that individuals with primary aldosteronism, a treatable condition, do not respond to RDN. For this reason, the practices followed at Penn for RDN include screening for secondary causes of hypertension, to include only patients with genuine medication intolerances to, or adherence issues with, hypertension medications.

The progress of RDN at Penn

Both of the FDA-approved systems for selective ablation of the renal arteries (radiofrequency and ultrasound) are available at Penn Medicine, and no other center in the region has as much experience with both devices.

A site for the original SYMPLICITY HTN-3, Penn has been a leader in the more contemporary RDN studies, specifically the studies involving the currently approved devices.

Case report

Mrs. M, a 78-year-old woman with a history of coronary artery disease, stenting, and atrial fibrillation complicated by strokes, was found to have uncontrolled hypertension at age 53 after an admission for a transient ischemic attack. She has had difficulty controlling her blood pressure of late, resulting in two recent ED admissions, one of which recorded a blood pressure of 213/87mmHg.

Mrs. M’s current medication history includes a clonidine patch, carvedilol, hydrochlorothiazide, and the recent addition of amlodipine. Her past medications include hydralazine, nebivolol, losartan, triamterene-hydrochlorothiazide, spironolactone, minoxidil, clonidine pills, and doxazosin.

Following a thorough workup for secondary causes of hypertension at Penn, no discernible reasons could be found for Mrs. M’s recent lack of HTN control.

Given the inability to control her blood pressure despite four current drugs and a history of multiple medication intolerances, Mrs. M was wary of the newer medications. When asked whether she’d consider renal denervation as an alternative, and counseled on the potential risks and benefits of the RDN, she agreed to proceed with the procedure.

The procedure

Several days later, Mrs. M presented to the cardiac catheterization lab, where, under conscious sedation and local anesthesia, a sheath was inserted into her right femoral artery under ultrasound guidance and aortography. A selective renal angiography was then performed, which confirmed that she did not have any anatomical exclusion for performing renal denervation.

Heparin was administered, and a 0.014” guidewire was then advanced into the renal arteries. The RDN catheter was then advanced into the target arteries (between 3-8mm in diameter) and the appropriate arteries were ablated.

All equipment was then removed, including the sheath. Mrs. M was watched for immediate procedural complications for several hours after the procedure and was ultimately discharged safely home on the same day as her procedure.

At her 2-month post-op follow-up, Mrs. M reported feeling like a different person. While her medication regimen hadn’t changed, her blood pressure readings now fell within the 114-134/55-70 range. At her last office visit, there were discussions about beginning to pull back on her medications.

Note: Mrs. M’s experience may not be typical for all patients.

About RDN at Penn Medicine

Interventional cardiologists at Penn Heart and Vascular Center partner with specialists from the Renal Electrolyte and Hypertension division to treat uncontrolled hypertension. Both entities manage patients with acute and chronic hypertension, and participate in renal denervation research at Penn Medicine.

Faculty

• Taisei Kobayashi, MD - Interventional Cardiology
• Debbie Cohen, MD - Nephrology

Clinical consult and patient referral

To refer a patient to Penn RDN, please call the renal denervation evaluation scheduling line at 215-662-4335.