The TUNA Procedure for BPH

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The TUNA Procedure for BPH: Basic Procedure and Clinical

Resultshttp://www.medscape.com/viewarticle/416646?src=searchfromInfections in Urology Muta M. Issa, MD, Samuel E. Myrick, MD, Nikolas P. Symbas, MD

Abstract and IntroductionAbstractWith transurethral needle ablation (TUNA), the inner region of the prostate is selectively ablated while theprostatic urothelium is preserved. This minimizes postoperative morbidity while maintaining impressivesubjective improvement (satisfied asymptomatic patients). The new TUNA instrumentation has simplified theprocedure and is expected to positively impact the procedure performance. The vigorous research anddevelopment in the field of prostate thermal therapy is responsible for the fast turnover in instrumentationdesigns to enhance performance. This is reflected in variations of results reported over a relatively shortperiod of time.

IntroductionVarious forms of minimally invasive thermal therapies have emerged, which include transurethral needleablation (TUNA) of the prostate,[1-14] transurethral microwave thermotherapy (TUMT), [15] interstitial laser

thermal therapy (ILTT),[16] and high-intensity focus ultrasound (HIFU) thermal therapy.[17] The TUNA procedurehas recently undergone extensive evaluation. It utilizes radio-fre-quency energy for thermal ablation. Thissecond installment of a 2-part series describes the basics of the TUNA procedure and presents an update ofthe clinical results as they apply to the treatment of benign prostatic hyperplasia (BPH).

The TUNA ProcedureThe TUNA procedure is performed with the patient in the lithotomy position, using 2% local lidocaineanesthesia per the urethra. The local anesthesia is supplemented with intravenous sedation whennecessary; however, we recently began using transperineal prostatic blocks to achieve total local anesthesiawithout the need for supplemental sedation. This technique allows the procedure to be performed in anoutpatient clinic setting without the need for conscious sedation monitoring.The appropriate length of the needles to be deployed and the number of planes to be treated are calculatedbased on the sonographic transverse diameter measurement of the prostate and the cystoscopic prostaticurethral length, respectively. The length of needle deployed (L) in millimeters is calculated using the formulaL equals 1/2 TD minus 6, where TD equals transverse diameter of the prostate on ultrasound in millimeters.This calculation ensures that the tip of the needle stays within the prostate, approximately 6mm from theprostatic capsule. The shields are deployed for 5mm to 6mm to cover the base of the needles adjacent to theTUNA catheter. The number of treatment planes are calculated based on the length of the prostatic urethra.We recommend 1 treatment plane for every 1cm to 1.5cm of prostatic urethra length, with a minimum of 2planes, irrespective of the urethral length. The planes are equidistant from each other in each lobe.The TUNA catheter is inserted transurethrally into the prostatic urethra, and its tip is positioned at the desiredtreatment plane. The needles and shields are then deployed and advanced into the prostatic lobe to theirappropriate lengths. A 4-minute "rise time," a 1- to 2-minute "hold time," and a target peripheral rimtemperature of 50C to 55C (122F-131F) are chosen. The radio frequency is delivered by the generator inan automated fashion to ensure a steady temperature rise of 3C to 4C (37.4F-39.2F)/minute at the

peripheral rim of the ablation region in the prostate. Temperature is measured via a thermosensor located atthe tip of the shields. There is a tendency for the urethral temperature to rise about 40C to 43C (104F-109.4F) during the treatment session due to heat conduction from the nearby ablation lesion; however,temperature may be quickly restored to baseline with the use of irrigation fluid. The same procedure isrepeated at different planes in the prostate according to the initial calculation.

Anesthesia Requirement During TUNAThere continues to be a wide variation in anesthesia used for TUNA among urologists and institutions. Thisvariation may be explained by the variability in urologist preference, the patient pain threshold, and the rulesand traditions of various medical institutions. Indeed, it is reasonable to use spinal or general anesthesia forthe first few TUNA cases. This facilitates the initial learning process and ensures one less thing about whichto worry. With a more experienced urologist, most patients (>90%) can undergo the TUNA treatment underlocal anesthesia.

Local anesthesia includes the topical instillation of lidocaine gel in the urethra combined with regionalinfiltration of lidocaine/marcaine into the prostate and paraprostatic tissue through various anatomicalapproaches, such as transperineal, retropubic, or transurethral prostatic blocks. Furthermore, supplementaloral or parenteral sedation/narcotics may be used. At our institution, we favor the transperineal prostatic
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block with intraurethral instillation of lidocaine gel -- without the use of supplemental sedation or narcotics --as the primary method. This obviates the need for conscious sedation monitoring, making it possible toperform the procedure in the outpatient clinic without elaborate and extensive set-up. Furthermore, itsignificantly reduces the global cost of the TUNA procedure by omitting operating room and anesthesiacharges.

Clinical Results

The first series of 12 TUNA procedures in the US was performed in 1994.[1]

Following this initial pilot study,the procedure underwent vigorous testing through various clinical trials to determine safety, efficacy, anddurability. A major clinical trial in the US compared TUNA to TURP in a randomized, controlled way.[4] Basedon the results of this study, the Food and Drug Administration approved TUNA in the US in October 1996.The procedure was also approved in Africa, Asia, Australia, Europe, and North and South America.In general, improvement is seen fairly early (within 2 weeks) and is usually complete within 6 weeks followingTUNA treatment. Occasionally, there is an impressive and complete resolution of the irritative voidingsymptoms within the first few days. Conversely, a few patients experience delayed and slow recovery,extending to 3 months. Possible explanations for this slow recovery include very small prostates, poor patientselection, suboptimal surgical technique leading to urothelial thermal injury, thermal ablation bladder necks,and treatment of enlarged median lobes. These reasons are observations, mostly anecdotal on our part, andhave not been studied specifically.

Subjective ImprovementSignificant subjective improvements in the symptom score have been reported in various series (Table I).[1,3,4,7,8-14] The overall average improvement is 58% at 1 year (546 patients in 10 series), 60% at 2 years, and66% at 3 years. Exclusion of the series with the "least" and "most" improvement (to minimize bias) did notimpact the results. These results were statistically significant when compared with baseline and surpass theexpected placebo range of 30%.With regard to the bother scores and quality-of-life scores, improvements were similar and parallel to theimprovements in symptom scores. In the US randomized trial comparing TUNA with TURP, theimprovements in all subjective parameters were similar following both procedures.[4]The improvement in the peak flow rate (Qmax) reported in the majority of the worldwide literature falls in therange of 60% to 80% (Table I). There are, however, 2 reports of significantly greater improvements of 121%and 280%.[12,14] Conversely, there are other series with notably lower improvement, 30%[11] and 33%[10]compared with over 50%, as expected. [1,3,4,7-9,12-14] Nonetheless, the latter 2 series reported significant

improvement in the symptom score, 66%[11] and 54%,[10] respectively. A summary of the worldwide literatureshows an overall average improvement in the peak flow rate (Qmax) to be 77% at 1 year (546 patients in 10series), 82% at 2 years, and 92% at 3 years. As with the results of the symptom score, these peak flow rateresults are statistically significant when compared with baseline and surpass the expected placebo range of30%.

Postvoid Residual UrineThe decrease in the postvoid residual (PVR) urine volume ranged from 13% to 80%. [4,7,8,13] The interpretationand clinical value of PVR have traditionally been overrated. Its current utility has been surpassed by variousother parameters. Therefore, less emphasis is currently placed on PVR, and many series have stoppedreporting on this parameter.[9,11,12,14]

Prostate Size

There is no convincing evidence that prostate size is significantly reduced following TUNA.[2,3,10,14] Astatistically significant decrease in the ultrasound size of the prostate has been reported; however, one hasto interpret this finding carefully and question its clinical significance.[1] This result may simply reflect the lowsensitivity and reliability of our current technique of transrectal prostate ultrasound in accurately measuringsmall changes in prostatic volume. Intraoperator variability is common and has to be taken into considerationso as not to over-credit volume changes measured by ultrasound.

Endoscopic Appearance of Prostatic Urethra

Figure 1. (click image to zoom)Cystoscopic appearance of prostate 3 months after TUNA procedure: (A)during "static" phase and (B) during "dynamic" voiding phase.
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Figure 2. (click image to zoom)Cystoscopic appearance of prostate 6 months following TUNA procedure. (A)Prostatic urothelium is markedly retracted at site of TUNA treatment in distal region (apex) of left prostatic

lobe. (B) Changes are more prominent in proximal region of left prostatic lobe, giving appearance of"tunneling."

Pressure Flow StudiesAt least 5 studies addressed detrusor pressures before and after TUNA (Table II).[1,9,12,14] The 2 largest seriesindicated that maximum detrusor pressure decreases significantly after TUNA. [9,13] The remaining 3 studies,[1,11,14] 1 of which had equivocal results, [1] suggested that obstruction persists despite the improvement in othersubjective, as well as objective, parameters. This raises important questions regarding the mechanismresponsible for therapeutic improvement following TUNA.

Adverse EventsTo date, no mortality has been reported with the TUNA procedure. Morbidity is relatively insignificant.

Urinary RetentionThe rate of postoperative urinary retention ranges from 13.3% to 41.6%.[1,3,4,7,12,13] The retention is transient(12-48 hours) in the majority of patients. During the initial learning phase, urinary retention is in the 40%range; however, this rate improves with more experience.

HematuriaA mild degree of transient macroscopic hematuria, which does not require specific treatment, is noted inmost patients for a period of 24 hours. Patients with significant coagulopathy may experience morepronounced hematuria and should be counseled about this preoperatively. It is recommended that suchcoagulopathy be corrected before the surgery. Antiplatelet agents, such as aspirin and nonsteroidal anti-inflammatory drugs, usually pose no major problems; however, patients are advised to discontinue these for7 to 10 days before TUNA if possible.

Irritative Voiding SymptomsDysuria and increased urinary frequency without urinary infection may develop in approximately 40% ofpatients during the initial postoperative period. These are mild and transient in nature, usually lasting 1 to 7days and rarely more than 2 to 4 weeks.

Urinary Infection and EpididymitisPostoperative urinary infection and epididymitis occur rarely (0% to 3.1%). [1-4,9,13] The risk of postoperativeinfection is minimized by ensuring urine sterility preoperatively and by the use of antibiotics. In ourexperience, fluoroquinolone antibiotics (500mg ciprofloxacin bid) given preoperatively and continued for 5days postoperatively have been effective in preventing urinary infection and epididymitis. Urinarymanipulation of an infection-susceptible organ, such as the prostate, in a setting of tissue necrosis requiresfull antibiotic coverage.

Urethral StricturesUrethral strictures occur in 0% to 1.5% of patients and are related to instrumentation of the urethra. [1-4,6,9,13] Therelatively small diameter of the TUNA catheter and the short duration of the treatment put the patient at lowerrisk for development of urethral stricture than after standard TURP. In the US randomized clinical trial, therate of urethral stricture was significantly lower following TUNA (1.5%) than following TURP (7.3%).[4]

Retrograde EjaculationNo objective evidence currently exists in the literature that retrograde ejaculation occurs following TUNA.However, a marginal decrease in the amount of ejaculatory fluid has been suggested in limited cases(without objective proof).[1,3] In 1 series, 13% of TUNA patients noticed some change. [3] It is possible thatmore aggressive TUNA therapy to the region of the bladder neck is responsible for this.

Erectile DysfunctionThe incidence of erectile dysfunction is negligible (0-


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deterioration and 21% both deterioration and improvement in sexual function were reported in the sameseries. To date, this report remains unique, unexplainable, and inconsistent with the majority of theworldwide literature.

TUNA in Patients With Urinary RetentionFew reports currently exist regarding the efficacy of TUNA in the treatment of urinary retention secondary toBPH.[14,18,19] Millard and others[14] reported an 85% (17/20) initial success rate, which later decreased to 75%

(15/20) when 2 patients underwent TURP for persistent voiding symptoms. Similarly, Zlotta and associates[19]

reported a 79% (30/38) success rate in patients with urinary retention.

Mechanism of Action of TUNAThe insignificant changes in prostate size and the disproportionate improvement of subjective as comparedwith objective parameters raise important questions regarding the mechanism of TUNA action. Anatomicdebulking is not significant, and improvement in peak flow rates and maximum detrusor pressures is lesspronounced than after anatomic debulking procedures such as TURP. Yet the improvement in the voidingsymptoms matches that of TURP. Therefore, one must question the traditional thinking of anatomicdebulking in BPH treatment and whether it is essential for the success of the treatment. This issue iscontroversial and requires closer analysis of BPH symptoms.

AUA Symptoms

The symptom score used by the American Urological Association explores 7 symptoms, both obstructive andirritative. Although it is difficult to categorize the various symptoms clearly into obstructive and irritative,approximately 3 are obstructive (weak stream, hesitancy, and intermittency) and 3 are irritative (frequency,urgency, and nocturia). The remaining 1 (feeling of incomplete bladder emptying) falls between the 2categories.An anatomic debulking procedure aims to unblock the prostatic urethra and is likely to improve theobstructive voiding symptoms. By design, this approach does not aim to treat the irritative voiding symptomsspecifically. Nonetheless, in the majority of patients (approximately 70% to 80%), improvement in theirritative voiding symptoms follows. Traditional thinking indicates that irritative symptoms are a result ofobstruction and that they should, therefore, improve once the obstruction is treated. This theory is supportedby the results of anatomical debulking procedures. However, this thinking may be challenged in the followingindividuals:(1) patients who experience continued voiding symptoms following TURP, laser prostatectomy, orintraprostatic stents, yet whose prostatic urethras appear nonobstructing on cystoscopy;(2) patients who have significant and bothersome voiding symptoms, yet whose prostates appear small andnonobstructing on cystoscopy;(3) patients who are responding satisfactorily to treatments with alpha-adrenergic blockers without decreasein the size of their prostates;(4) patients treated successfully with thermal therapies without decrease in size of their prostates; and(5) patients with cystoscopically obstructing prostate, yet who are asymptomatic.

BotherThe amount of bother patients experience is influenced more by their irritative rather than obstructivesymptoms. Indeed, patients are distressed by their inability to do basic daily activities, such as driving, orwatching a movie or game without interruption (frequency); inability to sleep through the night (nocturia); theembarrassment of rushing to the bathroom (urgency); and occasional urge incontinence. All of thesesymptoms are related to the irritative aspect of BPH. On the other hand, less bother is generally felt bypatients as they watch their intermittent weak stream or take an extra minute to complete voiding once theyreach the bathroom.For many years, urologists have designed procedures to treat BPH -- a condition of obstructive and irritativesymptoms -- that aim to treat obstruction even though irritative symptoms cause the majority of bother. Theadvent of thermal therapies has brought a new understanding of BPH symptoms. Patients may besatisfactorily treated in a minimally invasive way, without necessarily resulting in TURP-like flow rates anddetrusor pressures.There is increasing evidence that the therapeutic effect of TUNA is explained by intraprostaticneuromodulation, which alters the physiologic function of voiding (dynamic component of BPH). Thermalneural ablation, including surgical alpha-receptor blockade, has been demonstrated by various researchers.[20-22]

CostTUNA is performed as an outpatient clinic procedure under local anesthesia using topical intraurethrallidocaine gel and regional prostatic block. This allows the TUNA to be cost-effective by eliminating the fees


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associated with operating room, anesthesia team, recovery room, and conscious sedation monitoring. [2,23] Theability to perform TUNA under local anesthesia further augments its role as a "minimally invasive therapy." [2,23]

The current initial set-up cost of the TUNA system (generator and computer) is approximately $40,000 in theUS. This translates to approximately $500 to $800 per patient, based on the first 50 to 80 patients, to pay forthis initial investment. The cost of the disposables (catheter, ground pad, cables) is approximately $700 to$800 per case in the US. Currently, the global fee is approximately $3500 to $4000 in the US, which issignificantly less than the current global cost for TURP. These figures translate to approximately $1900 to

$2400 in professional and facility fees. Cost savings benefit the patient as well as the health care industry ingeneral, but more importantly, the patient benefits from a convenient, minimally invasive treatment. TheTUNA system is significantly less expensive than microwave thermal therapies (approximately $500,000 forthe Prostatron System from EDAP [Technomed, Burlington, Mass.] and $200,000 for the Targis System[Urologix, Minneapolis, Minn.]). With the current need for savings in our health care system, urologists shouldresist pressures and question the wisdom of paying up to 10 times more for an alternative thermal therapysystem.

The FutureAs with any new technology, further refinement in instrumentation and technique is expected. As with allthermal therapies, combined research and development efforts will further improve efficacy and durability.Furthermore, additional widespread experience is expected to enhance patient selection criteria forprediction and optimization of outcome.

ConclusionsThe rapid pace of research and development in the field of thermal therapy of the prostate continues to beresponsible for much of the potential variability in the clinical results. The era of prolonged clinical trials ofsingle, strict protocols is slowly disappearing for any new technology. The pressure to improve results bybetter instrumentation, computer software, and technique continues to fuel various revisions andimprovements in the field of minimally invasive therapies. The excitement of dynamic progress is pittedagainst the sense of uncertainty regarding the final outcome of new therapies. Therefore, enthusiasm fornew approaches must be tempered until convincing results become available. At the same time, one shouldnot overlook a good technology on the basis of attitude rather than fact. In general, it is a good policy toreview various reports and exclude those with the best and the worst results in order to minimize bias. Also,it is important to be aware of the changes in instrumentation and technique during clinical trials and how theyaffect the final outcome. For example, the TUNA system underwent improvement in optics, generators, andtechnique during the 3-year course of clinical trials (1994-1997). Changes usually have a positive impact onoutcome since they tend to be designed to correct problems of previous experience.TUNA holds promise for many patient populations, particularly elderly individuals with high surgical risk. Inaddition, the lack of significant risks, specifically those of incontinence and sexual dysfunction, makes thistreatment more attractive than TURP for many patients. Finally, the economic impact of TUNA is paramount:Cost has been reported to be significantly less (40%-70%) than that of TURP.

AcknowledgementsWe would like to thank Ms. Lois Elayne Miller, RN, and Ms. Katrina Anastasia, PA, for their contribution tothe minimally invasive BPH therapy program at The Atlanta Veterans Affairs Medical Center. We also wouldlike to thank Mr. Denis Roy, MBA, computer graphic designer, Department of Medical Media, AtlantaVeterans Affairs Medical Center, for preparing the illustrations, and Ms. Jill T. Issa for her editorialassistance.

Dr. Issa is Assistant Professor of Urology, Emory University School of Medicine in Atlanta, Ga., and Chief ofUrology, Atlanta Veterans Affairs Medical Center, Atlanta, Ga. Dr. Myrick is a Fellow in Urology at EmoryUniversity School of Medicine, Atlanta, Ga. Dr. Symbas is a Resident in Urology at Emory University Schoolof Medicine.

iInfect Urol 11(5):148-154, 1998. 1998 Cliggott Publishing, Division of SCP Communications

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The TUNA Procedure for BPH