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Join us as we discuss the global epidemic of hypertension with cardiologist Jeremy Bock. With over a third of the adult population affected and traditional treatments missing the mark for millions, Jeremy dives into the challenges of controlling high blood pressure and explores innovative solutions. Learn about the renal denervation (RDN) system—a new, minimally invasive procedure that offers hope for patients who struggle with conventional methods.

Jeremy Bock is a cardiologist.

He discusses the KevinMD article, “Renal denervation: a solution for hypertension patients worldwide.”

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Transcript

Kevin Pho: Hi, and welcome to the show. Subscribe at KevinMD.com/podcast. Today, we welcome Jeremy Bock. He’s an interventional cardiologist. Today’s KevinMD article is titled “Renal Denervation: A Solution for Hypertension Patients Worldwide.” Jeremy, welcome to the show.

Jeremy Bock: Thanks for having me. I really appreciate the invitation.

Kevin Pho: So let’s start by briefly sharing your story and journey.

Jeremy Bock: Sure. I’m an interventional cardiologist practicing outside Washington, D.C. I’ve been in practice for about 11 to 12 years. Even as a trainee, I was interested in the interaction between cardiac and renal physiology. Renal denervation, which was first developed about 15 to 20 years ago, really married those two interests.

As a cardiology fellow, I worked on the initial versions of the renal denervation catheter and have followed its development over the years. I was excited to be an early adopter and to incorporate it into my practice now that it’s ready for prime time.

Kevin Pho: Let’s talk more about that. You wrote about this in your KevinMD article, “Renal Denervation: A Solution for Hypertension Patients Worldwide.” Tell us about that article and the procedure for those who didn’t get a chance to read it.

Jeremy Bock: Sure. For some background, in the United States alone, it’s estimated that about 48 percent of the adult population has high blood pressure, which is roughly 120 million people. We also know that high blood pressure is the most common contributor to heart attack, stroke, and cardiac death. Clearly, better control needs to be a priority.

Of those 120 million people with high blood pressure, less than 25 percent are controlled according to current practice guidelines. Many patients are uncontrolled because their medications are not effective, or they’re not taking them as prescribed due to adherence issues. In general, the more antihypertensive medications patients are prescribed, the less adherent they tend to be.

So, from a public health perspective, we need a new way to approach this problem. Renal denervation has the potential to impact a significant number of patients worldwide.

Kevin Pho: Perfect. Take me through some of the physiology behind the procedure. For those who haven’t studied this in a while or need a refresher, explain the basics.

Jeremy Bock: Absolutely. The renal sympathetic nerves, which course along the renal artery as a web, are central to blood pressure regulation. These nerves act as the main communicators between the brain and the kidneys. When activated, they regulate blood pressure through a combination of salt and water handling and hormone output.

Interrupting this pathway limits the body’s ability to launch a hypertensive response. Catheter-based renal artery denervation selectively disables these nerves. Because these nerves are unmyelinated, they don’t regenerate, meaning the damage is permanent.

In my practice, I use a technology based on radiofrequency ablation. The energy generates heat, which selectively destroys the renal sympathetic nerves without damaging surrounding structures. Other platforms, such as ultrasound-based or alcohol ablation systems, achieve similar outcomes. The goal is to disable the renal sympathetic nerves, disrupting the body’s mechanisms for high blood pressure.

Kevin Pho: What kind of outcomes can one expect after undergoing this procedure?

Jeremy Bock: The pivotal trials that led to FDA approval demonstrated statistically significant blood pressure reductions at six months. These reductions were not only sustained but also grew over time, with registry data showing continued improvement out to three years.

Based on the studies, patients experienced a 15 to 25 millimeters of mercury drop in systolic blood pressure. In my clinical practice, the results have been even more robust. Among the patients I’ve treated, we’ve seen an average reduction of about 26 millimeters of mercury at six months.

This is significant because lowering blood pressure by just 10 millimeters of mercury reduces major cardiovascular events by 20 percent. A 26 millimeter drop represents a profound reduction in risk. Since the response is sustained and continues to improve, I believe we’re only scratching the surface of what this technology can achieve.

Our first goal is to bring patients’ blood pressure into the normal range. Once that’s achieved, we may be able to reduce or eliminate some of the multiple blood pressure medications these patients take daily. Many are on five or more medications, some dosed multiple times per day. This is a significant burden, and part of the challenge is understanding why nonadherence is so rampant. This technology offers a promising solution.

Kevin Pho: When you mention an initial 20-plus point drop in blood pressure, does it affect systolic and diastolic blood pressure equally?

Jeremy Bock: Most of the data focuses on systolic blood pressure, as the primary endpoints in trials were ambulatory systolic drops and office-based systolic drops. Diastolic blood pressure does decrease as well, but our primary focus has been on systolic reductions.

Kevin Pho: Realistically, are you seeing patients come in with, say, four or five blood pressure medications and leave the procedure able to remove most of them?

Jeremy Bock: Not yet. The early patients we’ve treated have been the most severe cases of uncontrolled hypertension—patients on five medications with systolic pressures in the 170s. Blood pressure reductions are gradual, which is a good thing. A precipitous drop could be unsafe and unpredictable. The slow and steady decline allows us to monitor patients, adjust medications, and ensure safety.

Jeremy Bock: The gradual decline over six months is reasonable and allows for regular follow-up visits. By tracking progress, we can optimize medications while observing the patient’s response to the procedure. The robust results we’re seeing at six months are very promising and align with the outcomes from clinical trials.

Kevin Pho: In the studies you mentioned, who were the patients being evaluated? What was the cohort?

Jeremy Bock: Great question. The inclusion criteria for the trials focused on patients with resistant hypertension. These are patients whose blood pressure remains uncontrolled despite taking three or more medications or those whose blood pressure is controlled but require four, five, or even six medications to achieve that control.

The study population included adults 18 years and older who met the criteria for resistant hypertension. Secondary causes of hypertension, such as renal artery stenosis, hyperaldosteronism, pheochromocytoma, or Cushing’s disease, were excluded. This cohort is similar to the population I target in my clinical practice.

Kevin Pho: You mentioned FDA-approved devices for renal denervation. Where are we now in terms of the availability of this technology?

Jeremy Bock: The FDA approved two platforms for renal artery denervation in November 2023. The first is the Medtronic Simplicity Spiral Catheter, which uses radiofrequency energy to generate heat and destroy the renal sympathetic nerves. The second is the ReCor Paradise System, an ultrasound-based catheter that uses a balloon-mounted ultrasound device to target and damage the nerves.

While the technology is FDA-approved, reimbursement remains a challenge. In the first year after approval, most procedures have been performed pro bono as part of early commercial programs. Recently, Medicare approved a transitional pass-through payment to help offset hospital costs, which is a significant step toward broader adoption and accessibility.

Kevin Pho: What can patients expect when undergoing this procedure? Walk us through the patient experience and potential complications.

Jeremy Bock: As an interventional cardiologist, most of my procedures are minimally invasive and catheter-based. For renal denervation, we don’t make incisions. Instead, we use a small plastic tube called a sheath to access the arterial system. Through this sheath, we pass long plastic catheters to the renal arteries. Once the procedure is complete, we seal the artery using a small plug. Recovery is minimal because there are no incisions or significant blood loss.

All the patients I’ve treated so far have undergone the procedure as outpatients and gone home the same day. This trend is consistent across national programs. Unlike stenting, no implants are left behind. The specialized catheter transmits radiofrequency energy to selectively damage the renal sympathetic nerves.

During the procedure, patients may experience discomfort, described as a tightening or aching in the flank regions. This is managed with moderate conscious sedation and narcotic analgesia to ensure patient comfort. All of my patients have tolerated the procedure well and experienced uneventful recoveries.

Complication rates are extremely low, as demonstrated in multiple multicenter, randomized, sham-controlled trials. Potential adverse events, such as renal artery dissection, thrombosis, or further renal impairment due to contrast administration, have been rare. Overall, the procedure has proven to be very safe.

Kevin Pho: Physiologically speaking, are the effects of this procedure permanent? Will patients need repeat procedures in the future?

Jeremy Bock: Based on what we know, the effects are permanent. The renal sympathetic nerves are unmyelinated, meaning they lack the protective myelin sheath required for regeneration. As a result, once these nerves are ablated, they do not regenerate. There’s no evidence to suggest that patients will need repeat procedures in the future.

Kevin Pho: As this technology evolves and reimbursement becomes more common, I’m an internal medicine primary care physician. When should I start considering this procedure for my patients? What types of cases should I be looking for?

Jeremy Bock: That’s a great question. As a primary care physician, you’ll encounter patients with resistant hypertension who have exhausted medical and lifestyle treatment options. These are the cases to consider for referral. When you find yourself at the limit of what you can do for a patient—when they’re on multiple medications with side effects, or their blood pressure remains uncontrolled despite your best efforts—renal denervation could be a reasonable next step.

This procedure isn’t meant to replace medical therapy or lifestyle changes. It’s an additional tool in our toolbox for patients with resistant hypertension who don’t respond to traditional approaches. The primary goal is to achieve blood pressure control, whether through medication, lifestyle changes, or procedural interventions, or most often a combination of all three.

Kevin Pho: In terms of the procedure itself, is this something most interventional cardiologists can learn and adopt into their practices?

Jeremy Bock: At the moment, only a minority of interventional cardiologists are performing this procedure, largely because it’s so new. Reimbursement challenges have also slowed adoption. Hospitals and private practices are understandably hesitant to absorb the costs. However, as reimbursement improves and the technology becomes more widely available, I expect more interventional cardiologists to incorporate renal denervation into their practices. Hypertension is such a common problem, and the need for better control is immense.

Kevin Pho: We’re talking to Jeremy Bock, an interventional cardiologist. Today’s KevinMD article is titled “Renal Denervation: A Solution for Hypertension Patients Worldwide.” Jeremy, let’s end with some take-home messages for the KevinMD audience.

Jeremy Bock: High blood pressure really is the silent killer. It affects roughly half the U.S. population and over a billion people worldwide. Despite our efforts with medical therapy and lifestyle modifications, many patients remain uncontrolled. This new technology represents a significant breakthrough.

Renal denervation has been proven safe and effective across multiple high-quality trials. In the coming years, I expect to see broader adoption and greater accessibility, allowing us to offer this promising solution to more patients. With better blood pressure control, we can significantly reduce the risks of heart attack, stroke, and other cardiovascular events.

Kevin Pho: Jeremy, thank you so much for sharing your perspective and insight. Thanks again for coming on the show.

Jeremy Bock: Thank you for having me. It’s been a pleasure.