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Stephen B Solomon

Publications and source records attributed to Stephen B Solomon.

At least 37 records · Page 2Linked to original sources
PubMed2005

Percutaneous radio frequency ablation of renal masses: results at a 2-year mean followup.

PURPOSE: We describe our experience with and results of percutaneous computerized tomography guided radio frequency ablation (RFA) for small (less than 4 cm) renal tumors at a 2-year mean followup. MATERIALS AND METHODS: A total of 49 patients (60 renal tumors) with a mean age of 63.9 years underwent percutaneous RFA. Indications for RFA were severe comorbidities or previous abdominal surgery precluding operative management, or hereditary conditions predisposing to multiple tumor recurrence. Persistent enhancement on initial followup imaging was considered incomplete treatment and all such patients underwent biopsy and were offered repeat RFA. Enhancement or enlargement on subsequent imaging was considered tumor recurrence and these patients were counseled regarding further therapy. RESULTS: Three patients (4 tumors) were excluded from evaluation due to death from unrelated causes or loss to followup. A total of 46 patients (56 tumors) were available for evaluation at a mean followup of 27.5 months (range 12 to 48). Six tumors were incompletely treated with the first RFA and successfully treated with a second session. Recurrences after successful initial treatment were seen in 3 of 46 patients. These recurrences developed 24, 25 and 31 months following RFA, respectively, and all occurred in patients with a central tumor of 3.0 cm or greater. Overall local control was achieved in 94.6% of tumors (53 of 56). CONCLUSIONS: RFA is an emerging alternative treatment modality for small renal tumors. Larger (greater than 3.0 cm) central tumors represent unique technical challenges, making these tumors more prone to recurrence. Long-term followup is needed to establish the oncological durability of this technique.

Adult↗
PubMed2004

Evaluation of water jet morcellation as an alternative to hand morcellation of renal tissue ablation during laparoscopic nephrectomy: an in vitro study.

OBJECTIVES: To evaluate the feasibility and safety of morcellation with a new prototype device that uses high-pressure water flow as a cutting/ablating tool and compare it with standard manual morcellation. METHODS: Ten porcine kidneys were morcellated with the new water jet device and ten with conventional manual morcellation. Morcellation in all cases was performed in commercially available entrapment bags. The two groups were evaluated for morcellation time, fragment size, and perforation rates (macroscopic and microscopic). RESULTS: The kidney size in both groups was similar. Morcellation was significantly (P <0.0001) faster in the water jet morcellator group than in the hand morcellation group (5.6 versus 11.9 minutes). The macroscopic evaluation after filling the entrapment bags with normal saline revealed 4 (40%) and 2 (20%) pinhole perforations in the water jet and hand morcellation groups, respectively. The microscopic evaluation revealed an 80% perforation rate in the water jet group and a 20% rate in the hand morcellator group. The size of the resulting fragments in the water jet group was not available, because the morcellated kidney was transformed in a semiliquid form. Therefore, cytology evaluation of the tissue was not possible. CONCLUSIONS: Water jet technology can be used to morcellate renal porcine tissue effectively. It is faster, but the problems of safety and histologic evaluation must be solved before this promising technology can be used in a clinical setting.

Animals↗
PubMed2004

Stereotactic magnetic resonance guidance for anatomically targeted ablations of the fossa ovalis and the left atrium.

INTRODUCTION: Targets for radiofrequency ablation (RFA) of atrial fibrillation are increasingly being selected based on anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures, we evaluated whether stereotactic catheter guidance might facilitate anatomical catheter navigation and RFA to the great vessels, the fossa ovalis and the left atrium (LA). METHODS AND RESULTS: An electromagnetic catheter's position system was superimposed on three-dimensional (3D) MR images using fiducial markers. This allowed the dynamic display of the catheter position on the true anatomy of previously acquired MRI in real-time. To assess the reproducibility of RFA, repeat ablations were created at the identical anatomic site in the inferior vena cava (IVC) in 5 swine. Average distance of the repeated ablations was 4.4 +/- 2.4 mm.In five swine the catheter was anatomically guided with the MRI to the fossa ovalis and a single RFA was performed. On the pathological specimen all ablation sites were located within the fossa ovalis with an average distance of 3.9 +/- 2.1 mm from its center. In two of the experiments the ablation catheter was passed into the left atrium and anatomically targeted ablation performed in the lateral wall of the left atrial appendage. Catheter location and ablation site were confirmed by autopsy and histology. CONCLUSION: Real-time display of the catheter position on 3D-MRI allows anatomically targeted catheter navigation and RFA in the IVC, the fossa ovalis, and the left atrium. This may facilitate anatomically based interventions like septal puncture or pulmonary vein ablation and decrease fluoroscopy times.

Animals↗
PubMed2004

The future of interventional cardiology lies in the left atrium.

The historic focus of interventional cardiology has been on treating atherosclerotic coronary artery disease. Balloons, stents, and debulking devices have been the mainstay tools of the interventionalist. However, as engineering skills have developed and clinical techniques have improved, new clinical avenues for the interventionalist beyond the coronary vessels are starting to evolve. One of the most opportunistic areas in cardiology for the interventionalist is the left atrium where treatment of clinically important issues such as mitral regurgitation, left atrial thrombus, atrial fibrillation, patent foramen ovale, and atrial septal defect may be approached. Additionally, the left atrium is a source of important hemodynamic information that can be captured with new implantable devices. While in the past the trans-septal puncture has been infrequently used, the future may hold this technique as one of the most common. The following manuscript describes the status of some of the newest opportunities for interventionalists that lie beyond atherosclerotic disease and within the left atrium.

Atrial Fibrillation↗
PubMed2004

Defining the complications of cryoablation and radio frequency ablation of small renal tumors: a multi-institutional review.

PURPOSE: Ablative treatments (cryoablation or radio frequency ablation) for renal cell carcinoma aim to decrease morbidity by treating renal tumors in situ, eliminating the need for extirpation. These technologies have potential for complications previously unassociated with renal tumor treatment. We identified complications associated with percutaneous and laparoscopic ablative treatment of renal tumors. MATERIALS AND METHODS: Groups at medical centers with reported experience with ablation of renal tumors were invited to participate in this study. Each group submitted retrospective data regarding overall ablative treatment experience and associated complications. For each incident the nature of the complication, its associated morbidity, the necessity and nature of any subsequent interventions, and the final patient outcome were evaluated. Complications were divided into minor and major categories. Data were collected from groups at 4 institutions with a combined experience of 271 cases. Of these cases 139 were cryoablation and 133 were radio frequency ablation. There were 181 procedures performed percutaneously and 90 performed laparoscopically. RESULTS: A total of 30 complications occurred (11.1%) with 5 major (1.8%) and 25 minor (9.2%) complications, and 1 death (0.4%). Overall 26 of the 30 complications (86.7%) were directly attributable to the ablation procedure. The most common complication was pain or paraesthesia at the probe insertion site. CONCLUSIONS: Ablation technologies appear to have a low complication profile when used to treat small renal tumors. The majority of complications are minor and require observation only. Further study and followup are necessary to determine long-term oncological efficacy.

Adult↗
PubMed2003

Anatomic stereotactic catheter ablation on three-dimensional magnetic resonance images in real time.

BACKGROUND: Targets for radiofrequency (RF) ablation of atrial fibrillation, atrial flutter, and nonidiopathic ventricular tachycardia are increasingly being selected on the basis of anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures and is associated with radiation risk, other approaches to mapping may be beneficial. METHODS AND RESULTS: An electromagnetic catheter positioning system was superimposed on 3D MR images using fiducial markers. This allowed the dynamic display of the catheter position on the true anatomy of previously acquired MR images in real time. In vitro accuracy and precision during catheter navigation were assessed in a phantom model and were 1.11+/-0.06 and 0.30+/-0.07 mm (mean+/-SEM), respectively. Left and right heart catheterization was performed in 7 swine without the use of fluoroscopy, yielding an in vivo accuracy and precision of 2.74+/-0.52 and 1.97+/-0.44 mm, respectively. To assess the reproducibility of RF ablation, RF lesions were created repeatedly at the identical anatomic site in the right atrium (n=8 swine). Average distance of the repeated right atrial ablations was 3.92+/-0.5 mm. Straight 3-point lines were created in the right and left ventricles to determine the ability to facilitate complex ablation procedures (n=6 swine). The ventricular lesions deviated 1.70+/-0.24 mm from a straight line, and the point distance differed by 2.25+/-0.63 mm from the pathological specimen. CONCLUSIONS: Real-time display of the catheter position on 3D MRI allows accurate and precise RF ablation guided by the true anatomy. This may facilitate anatomically based ablation procedures in, for instance, atrial fibrillation or nonidiopathic ventricular tachycardia and decrease radiation times.

Animals↗
PubMed2003

Percutaneous computed tomography-guided radiofrequency ablation of renal masses in high surgical risk patients: preliminary results.

This article evaluates the safety and efficacy of percutaneous radiofrequency ablation (RFA) delivered by computed tomography (CT) fluoroscopic guidance for the treatment of small, solitary renal lesions in high risk surgical and anesthetic patients. In total, 29 patients with 35 small (</=4 cm) renal lesions underwent a total of 37 CT fluoroscopically guided RFA treatments using a dry RFA technique. Because of medical comorbidities, 26 patients were considered high surgical risk candidates, and 3 patients had von Hippel-Lindau disease. Procedures were performed percutaneously, under intravenous sedation and on an outpatient basis. Renal lesions were monitored on a 3-month basis using precontrast- and postcontrast-enhanced CT imaging to assess for the presence of growth or residual lesion enhancement. Of 37 RFA treatments, 35 (95%) were successfully performed under intravenous sedation and 32 (86%) treatments were performed on an outpatient basis. Over a mean radiographic follow-up period of 9 months, 33 of 35 (94%) renal lesions have required only a single RFA treatment, and 2 patients required a second, successful retreatment for small regions of residual enhancement on follow-up CT imaging. Of 13 renal lesions with a >/=12-month radiographic follow-up interval, 11 (85%) have demonstrated no residual enhancement or growth after RFA. Percutaneous RFA of small, solitary renal lesions is well tolerated in high surgical risk patients. Although early results are encouraging, longer-term follow-up time is necessary to determine the precise role of RFA in this patient population. high resolution video, medium resolution video, low resolution video

Aged↗
PubMed2003

Real-time cardiac catheter navigation on three-dimensional CT images.

INTRODUCTION: Targets for ablation of atrial fibrillation, atrial flutter, and non-idiopathic ventricular tachycardia are increasingly being selected based on anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures, and is associated with radiation risk, other approaches to mapping may be beneficial. METHODS: The spatial and temporal information of an electromagnetic catheter tip position sensing system (Magellan, Biosense Inc.) was superimposed on a three-dimensional (3D) CT of the chest in swine using fiducial markers for image registration. Position and orientation of a 6 French catheter with an electromagnetic sensor was displayed in real-time on a corresponding 3D-CT. Catheter navigation within the heart and the great vessels was guided by detailed knowledge about catheter location in relation to cardiac anatomy. RESULTS: Anatomic structures including the atrial septum, pulmonary veins, and valvular apparatus were easily identified and used to direct catheter navigation. During the right heart examination, the catheter was navigated through the superior and inferior vena cava to predetermined anatomic locations in right atrium, right ventricle and pulmonary artery. The ablation catheter was also navigated successfully from the aorta through the aortic valve in the left ventricle. No complication was encountered during the experiments. The accuracy and precision of this novel approach to mapping was 4.69 +/- 1.70 mm and 2.22 +/- 0.69 mm, respectively. CONCLUSIONS: Real-time display of catheter position and orientation on 3D-CT scans allows accurate and precise catheter navigation in the heart. The detailed anatomic information may improve anatomically based procedures like pulmonary vein ablation and has the potential to decrease radiation times.

Animals↗
PubMed2003

Initial experience with a novel focused ultrasound ablation system for ring ablation outside the pulmonary vein.

INTRODUCTION: Atrial fibrillation has been shown to initiate from triggers within pulmonary veins. Several studies have documented that electrical isolation of those triggers can lead to maintenance of sinus rhythm. The complication of pulmonary vein stenosis has limited the utility of delivering ablation energy within the pulmonary vein. We utilize a focused ultrasound catheter ablation system for delivery of transmural ablation lines proximal to the pulmonary vein ostium. METHODS: Nine dogs (weight 30-39 kg) were anesthetized and ventilated. Through a transseptal approach, pulmonary veins were engaged with the focused balloon ultrasound catheter. Ultrasound power was delivered at 40 acoustic watts outside the pulmonary vein ostium, focused 2 mm off the balloon surface, with a depth of approximately 6 mm, for 30-120 seconds. Following ablation, lesions were histopathologically analyzed. RESULTS: Of nine animals studied, fourteen pulmonary veins were ablated. We found successful delivery of near circumferential and transmural ablation lines in 6/14 pulmonary veins. In each of the six circumferential ablations, successful alignment of the ultrasound transducer along the longitudinal axis of the parabolic balloon occurred. The final four ablations were conducted with an enhanced catheter design that assured axial alignment. Of these ablations, all four were circumferential. The remaining 8 pulmonary veins had incomplete delivery of lesions. In each of these veins the ultrasound transducer was misaligned with the balloon axis when therapy was delivered. CONCLUSION: Focused ultrasound ablation is a new means of performing pulmonary vein isolation. This method provides delivery of lesions outside the vein, limiting the risk of pulmonary vein stenosis for the treatment of atrial fibrillation.

Animals↗
PubMed2003

Interstitial photon radiation.

Most minimally invasive ablative techniques utilize thermal energies for tissue destruction. However, the heat-sink phenomenon may limit the efficacy of radiofrequency ablation and cryotherapy of tissue near blood vessels. One alternative non-temperature-dependent ablative technique is photon radiation. This radiation is dependent on energy and intensity, and its effects are influenced only by the density of the surrounding tissue. Photon radiation therapy may offer a unique alternative for ablating tissue surrounding vascular structures.

Animals↗
PubMed2003

Histologic evolution of high-intensity focused ultrasound in rabbit muscle.

RATIONALE AND OBJECTIVES: The purpose of this study was to examine the histologic evolution over time of rabbit skeletal muscle thermally ablated with high-intensity focused ultrasound. The objectives included determining the extent and focality of damage created by this noninvasive, transcutaneous ablative technology. METHODS: Transcutaneous, thermal ablation with an external focused ultrasound transducer was applied to the paraspinous muscles of 19 rabbits. At varying times, up to 100 days after therapy, single sonications were examined histologically. RESULTS: Initially, only subtle staining changes were identified within lesions. In the chronic phase (day 51-100), the muscle was replaced or infiltrated by variable amounts of scar and fat similar to degenerative muscle disorders. Histologic changes were limited to the tissue within the intensity focus of the transducer and were not seen in intervening tissues. DISCUSSION: The current study took a systematic approach to study the long term, in vivo histologic effects of single HIFU lesions in a nonregenerative tissue. This experience in muscle tissue will provide a basis for understanding ultrasound effects for clinical applications such as treatment of uterine fibroids, cardiac tissue, and sarcomas.

Animals↗
PubMed2003

Talc pleurodesis mimics pleural metastases: differentiation with positron emission tomography/computed tomography.

Talc pleurodesis is a technique used in the treatment of patients with persistent pleural effusions or pneumothorax not amenable to other treatment. These are commonly seen in patients with malignant thoracic neoplasms. Radiographic abnormalities resulting from prior talc pleurodesis could be confused with progression of the underlying neoplastic process. Positron emission tomography with F-18 fluorodeoxyglucose (FDG-PET) might be unable to distinguish between malignant and benign inflammatory processes. This report demonstrates the use of combined positron emission tomography/computed tomography (PET/CT) in a patient with a history of both malignant neoplasm and a prior talc pleurodesis. Fusion of PET and CT studies could add information that CT and PET alone cannot. This could alter the diagnostic and therapeutic course for patients with a history of both thoracic neoplasm and talc pleurodesis.

Chylothorax↗
PubMed2002

Focused ultrasound ablation of the epididymis with use of thermal measurements in a canine model.

OBJECTIVE: To explore the epididymis as an alternative anatomical target to the vas deferens for noninvasive male sterilization using therapeutic focused ultrasound. DESIGN: Controlled preclinical study. SETTING: Canine animal model in an academic research environment. PATIENT(S): Four healthy male mongrel dogs (30-35 kg). INTERVENTION(S): A transducer mounted on a plastic clip delivered ultrasound energy to the canine epididymis. Thermocouples placed transcutaneously into the epididymis, intradermally, and on the skin surface recorded temperatures during ablation with a wide range of acoustic powers and sonication times (control, 3 W/120 s, 5 W/90 s, 7 W/60 s). MAIN OUTCOME MEASURE(S): Thermocouple temperature measurements determined the optimal range of ablation parameters that produced successful thermal occlusion of the epididymis without adverse effects (e.g., skin burns, testicular injury). RESULT(S): A large "therapeutic window" was determined (power = 3-7 W, time = 20-120 seconds) over which noninvasive thermal occlusion of the epididymis can be achieved. Thermal occlusion rates were higher, and complications lower, than found previously with vas deferens ablation. CONCLUSION(S): The epididymis represents a larger and easier target than the vas deferens for performing noninvasive male sterilization using focused ultrasound. Long-term azoospermia studies will be necessary to confirm permanent sterilization with this technique.

Animals↗
PubMed2002

Percutaneous gadolinium injection under MR guidance to mark target for CT-guided radiofrequency ablation.

Selection of the appropriate imaging tool depends on a number of factors that reflect the patient, the procedure, and the physician. Multiple imaging techniques are often required to perform elements of a whole procedure. A patient with an allergy to iodinated contrast material and a 3.0-cm hepatic metastasis that was invisible on computed tomography (CT) was treated with CT-guided radiofrequency ablation by first injecting gadolinium under magnetic resonance guidance to mark the location of the lesion. Gadolinium's high atomic number makes it a viable contrast agent for attenuating x rays under fluoroscopic or CT guidance.

Aged↗
PubMed2002

High-intensity focused ultrasound ablation of the epididymis in a canine model: a potential alternative to vasectomy.

BACKGROUND AND PURPOSE: High-intensity focused ultrasound (HIFU) is a noninvasive technology capable of inducing thermal coagulative necrosis of subsurface structures without injuring intervening tissues. We have previously reported on the feasibility of HIFU vasectomy in a canine model. In this study, we evaluated the feasibility of HIFU ablation of the canine epididymis as an alternative to vasectomy. The epididymis may be a better target than the vas deferens because it is larger, more easily positioned in the HIFU focal zone, and more susceptible to occlusive injury at lower energy levels, thus reducing collateral damage. MATERIALS AND METHODS: A hand-held HIFU clamp was used to grasp the epididymides of anesthetized dogs (eight surgically exposed and six grasped transcutaneously). An ultrasound transducer in the clamp focused energy on a 1 x 3 x 8-mm target zone centered between the clamp jaws. Ultrasonic energy (6-19 W) was delivered to this target zone for various times (16-150 seconds). The vas, epididymis, and testis were harvested for histologic examination 2 weeks after ablation. RESULTS: Seven of the eight epididymides ablated after surgical exposure demonstrated histologic findings associated with occlusion (fibrosis, hemorrhage, and proximal duct dilatation). Five of the six epididymides ablated transcutaneously also demonstrated histologic evidence of occlusion. Skin burns were evident overlying three epididymides, and one testicular injury was noted adjacent to an ablated region of the epididymis. CONCLUSION: High-intensity focused ultrasound ablation of the epididymis causes injury and histologic changes associated with epididymal occlusion. Further investigations are under way to optimize ablation parameters and to confirm azoospermia with ejaculate studies. Refinement of this technology may provide a rapid noninvasive alternative to conventional vasectomy.

Animals↗
PubMed2002

Robotic percutaneous access to the kidney: comparison with standard manual access.

PURPOSE: To evaluate the efficiency, accuracy, and safety of robotic percutaneous access to the kidney (PAKY) for percutaneous nephrolithotomy in comparison with conventional manual techniques. MATERIALS AND METHODS: We compared the intraoperative access variables (number of access attempts, time to successful access, estimated blood loss, complications) of 23 patients who underwent robotic PAKY with the remote center of motion device (PAKY-RCM) with the same data from a contemporaneous series of 23 patients who underwent conventional manual percutaneous access to the kidney. The PAKY-RCM incorporates a robotic arm and a friction transmission with axial loading system to accurately position and insert a standard 18-gauge needle percutaneously into the kidney. The blood loss during percutaneous access was estimated on a four-point scale (1 = minimal to 4 = large). The color of effluent urine was graded on a four-point scale (1 = clear to 4 = red). RESULTS: The mean target calix width was 13.5 +/- 9.2 mm in the robotic group and 12.2 +/- 4.5 mm in the manual group (P = 0.57). When comparing PAKY-RCM with standard manual techniques, the mean number of attempts was 2.2 +/- 1.6 v 3.2 +/- 2.5 (P = 0.14), time to access was 10.4 +/- 6.5 minutes v 15.1 +/- 8.8 minutes (P = 0.06), estimated blood loss score was 1.3 +/- 0.49 v 1.7 +/- 0.66 (P = 0.14), and color of effluent urine following access was 2.0 +/- 0.90 v 2.1 +/- 0.7 (P = 0.82). The PAKY-RCM was successful in obtaining access in 87% (20 of 23) of cases. The other three patients (13%) required conversion to manual techniques. There were no major intraoperative complications in either group. CONCLUSIONS: Robotic PAKY is a feasible, safe, and efficacious method of obtaining renal access for nephrolithotomy. The number of attempts and time to access were comparable to those of standard manual percutaneous access techniques. These findings provide the groundwork for the development of a completely automated robot-assisted percutaneous renal access device.

Blood Loss, Surgical↗