Convective Water Vapor Energy for Lower Urinary Tract Symptoms/Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) refers to proliferation of smooth muscle and epithelial cells within the transition zone of the prostate. Half of men over 40 develop histologic BPH. About half of men with BPH develop an enlarged prostate gland, called benign prostatic enlargement; among these, about half develop some degree of bladder outlet obstruction. Bladder outlet obstruction and changes in smooth muscle tone and resistance may result in lower urinary tract symptoms, including storage disturbances (such as daytime urinary urgency, frequency, and nocturia) and voiding disturbances (such as urinary hesitancy, weak urinary stream, straining to void, and prolonged voiding).

Key points

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Benign prostatic hyperplasia (BPH) is a histologic diagnosis that refers to the proliferation of smooth muscle and epithelial cells within the transition zone of the prostate.
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Half of men over the age of 40 develop histologic BPH. About half of men with BPH develop an enlarged prostate gland, called benign prostatic enlargement (BPE); among these, about half develop some degree of bladder outlet obstruction.
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Bladder outlet obstruction and/or changes in smooth muscle tone and resistance that can accompany BPH may result in lower urinary tract symptoms (LUTS).
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LUTS include storage disturbances (such as daytime urinary urgency, frequency, and nocturia) and/or voiding disturbances (such as urinary hesitancy, weak urinary stream, straining to void, and prolonged voiding).
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Treatment requires either medical or surgical intervention. Efforts to use minimally invasive treatments for BPH have included transurethral microwave therapy, transurethral needle ablation, and the use of the prostatic urethral lift.
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Recent publication of 1-year data shows convective water vapor as a promising improvement in both the subjective symptoms and the objective findings associated with symptomatic BPH while having negligible negative impact on erectile and ejaculatory function.

Introduction

Benign prostatic hyperplasia (BPH) is a frequently encountered chronic urologic condition that is associated with the development of lower urinary tract symptoms (LUTS) and impacts quality of life (QOL). BPH prevalence increases with age and often requires either medical or surgical treatment and is associated with high costs in men older than 50 years of age. Per the American Urological Association guidelines, men with moderate and severe BPH should be offered therapy. Although transurethral resection of the prostate (TURP) is used less commonly in contemporary practice, it remains the gold standard for BPH refractory to medical management. Bipolar TURP is associated with less intraoperative adverse events than monopolar TURP. Unfortunately, many of the more efficacious surgical therapies for BPH are associated with a significant risk of ejaculatory dysfunction (EjD) and lesser risk of erectile dysfunction (ED). In particular, TURP causes EjD in approximately 65% of men and ED in less than 10%.

Efforts to use minimally invasive treatments for BPH have included transurethral microwave therapy (TUMT), transurethral needle ablation (TUNA), and use of the prostatic urethral lift, among many other options. TUMT and TUNA require a high temperature gradient to facilitate adequate temperature delivery (convection) to the prostatic adenoma to induce necrosis. Both of these therapies are associated with limited durability. The Rezum System (NxThera, Inc, Maple Grove, MN, USA) uses convection to deliver energy to the prostate and induce necrosis and requires no thermal gradient. Water vapor disperses into the prostatic tissue. Recent publication of 1-year data shows a promising improvement in both the subjective symptoms and the objective findings associated with symptomatic BPH while having negligible negative impact on ED/EjD.

Introduction

Benign prostatic hyperplasia (BPH) is a frequently encountered chronic urologic condition that is associated with the development of lower urinary tract symptoms (LUTS) and impacts quality of life (QOL). BPH prevalence increases with age and often requires either medical or surgical treatment and is associated with high costs in men older than 50 years of age. Per the American Urological Association guidelines, men with moderate and severe BPH should be offered therapy. Although transurethral resection of the prostate (TURP) is used less commonly in contemporary practice, it remains the gold standard for BPH refractory to medical management. Bipolar TURP is associated with less intraoperative adverse events than monopolar TURP. Unfortunately, many of the more efficacious surgical therapies for BPH are associated with a significant risk of ejaculatory dysfunction (EjD) and lesser risk of erectile dysfunction (ED). In particular, TURP causes EjD in approximately 65% of men and ED in less than 10%.

Efforts to use minimally invasive treatments for BPH have included transurethral microwave therapy (TUMT), transurethral needle ablation (TUNA), and use of the prostatic urethral lift, among many other options. TUMT and TUNA require a high temperature gradient to facilitate adequate temperature delivery (convection) to the prostatic adenoma to induce necrosis. Both of these therapies are associated with limited durability. The Rezum System (NxThera, Inc, Maple Grove, MN, USA) uses convection to deliver energy to the prostate and induce necrosis and requires no thermal gradient. Water vapor disperses into the prostatic tissue. Recent publication of 1-year data shows a promising improvement in both the subjective symptoms and the objective findings associated with symptomatic BPH while having negligible negative impact on ED/EjD.

Rezum system

Thermal treatment using the Rezum system involves a radiofrequency energy source within the handle to generate water vapor that intercalates with prostatic tissue. Conduction is the transfer of heat from an area of higher temperature to lower temperature. TUMT and TUNA energy transfer is done via conductive transfer, which requires a higher energy gradient. Rezum uses convection, which is the movement of a heated gas or liquid within a space.

With the patient in lithotomy position, treatment is administered via a standard transurethral approach with rigid cystoscopy. Patients treated on trial had the procedure performed with the aid of oral medications or under intravenous sedation. Under direct visualization, a polyether ether ketone (PEEK) needle is used to deliver the vapor with 9-second injections and allows for targeted treatment ( Fig. 1 ). The needle achieves a depth of 10 mm and circumferentially delivers the vapor. In the initial safety study, each lateral lobe received a mean of 4.6 injections. Twenty-two percent required treatment of their median lobe with a mean of 1.8 injections. The vapor enters the cellular interstices of the prostatic adenoma. The tissue treated with the vapor reaches 70°C to 80°C, which causes immediate cell death. Injections commence 1 cm from the bladder neck at the 3 o’clock and 9 o’clock positions and are spaced in 0.5- to 1.0-cm intervals. Clearly, the number of injections required depends on prostate volume and anatomical configuration.