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Dive into the research topics where Ryan Z. Swan is active.

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Featured researches published by Ryan Z. Swan.


Annals of Surgery | 2014

Microwave ablation for hepatic malignancies: a multiinstitutional analysis.

Ryan T. Groeschl; Charles Henry Caldow Pilgrim; Erin M. Hanna; Kerri A. Simo; Ryan Z. Swan; David Sindram; John B. Martinie; David A. Iannitti; Mark Bloomston; Carl Schmidt; Hooman Khabiri; Lawrence A. Shirley; Robert C.G. Martin; Susan Tsai; Kiran K. Turaga; Kathleen K. Christians; William S. Rilling; T. Clark Gamblin

Objective:This study hypothesized that tumor size, number of tumors, surgical approach, and tumor histology significantly affected microwave ablation (MWA) success and recurrence-free survival. Background:Although many hepatobiliary centers have adopted MWA, the factors that influence local control are not well described. Methods:Consecutive patients with hepatic malignancy treated by MWA were included from 4 high-volume institutions (2003–2011) and grouped by histology: hepatocellular carcinoma (HCC), colorectal liver metastases, neuroendocrine liver metastases, and other cancers. Independent significance of outcome variables was established with logistic regression and Cox proportional hazards models. Results:Four hundred fifty patients were treated with 473 procedures (139 HCC, 198 colorectal liver metastases, 61 neuroendocrine liver metastases, and 75 other) for a total of 875 tumors. Median follow-up was 18 months. Concurrent hepatectomy was performed in 178 patients (38%), and when performed was associated with greater morbidity. Complete ablation was confirmed for 839 of 865 tumors (97.0%) on follow-up cross-sectional imaging (10 were unevaluable). A surgical approach (open, laparoscopic, or percutaneous) had no significant impact on complication rates, recurrence, or survival. The local recurrence rate was 6.0% overall and was highest for HCC (10.1%, P = 0.045) and percutaneously treated lesions (14.1%, P = 0.014). In adjusted models, tumor size 3 cm or more predicted poorer recurrence-free survival (hazard ratio: 1.60, 95% CI: 1.02–2.50, P = 0.039). Conclusions:In this large data set, patients with 3 cm or more tumors showed a propensity for early recurrence, regardless of histology. Higher rates of local recurrence were noted in HCC patients, which may reflect underlying liver disease. There were no significant differences in morbidity or survival based on the surgical approach; however, local recurrence rates were highest for percutaneously ablated tumors.


International Journal of Medical Robotics and Computer Assisted Surgery | 2016

Robotic pancreaticoduodenectomy: comparison of complications and cost to the open approach

E. Baker; Samuel W. Ross; Ramanathan M. Seshadri; Ryan Z. Swan; David A. Iannitti; Dionisios Vrochides; John B. Martinie

Robotic pancreaticoduodenectomy (RP) has shown some advantages over open pancreaticoduodenectomy (OP) but no data has been published providing a cost comparison.


Hpb | 2011

Real-time three-dimensional guided ultrasound targeting system for microwave ablation of liver tumours: a human pilot study.

David Sindram; Ryan Z. Swan; Kwan N. Lau; Iain H. McKillop; David A. Iannitti; John B. Martinie

OBJECTIVES This study aimed to evaluate a novel three-dimensional ultrasound (US) guidance system for use in hepatic microwave ablation (MWA). METHODS An in vitro assessment was performed in which users with different degrees of experience were evaluated for accuracy in targeting phantom lesions embedded in agar using US alone, or US in conjunction with the InVision™ System (IVS). An eight-patient pilot trial of the IVS was then performed in the setting of open hepatic MWA, in which lesions would otherwise have been targeted with conventional US. RESULTS In vitro studies demonstrated that the IVS significantly improved targeting accuracy at all levels of operator experience (novice, beginner and expert). In the human trial, a total of 31 tumours were targeted and all lesions were hit in one pass, as assessed by independent US image observations. There were no adverse operative events; however, there was minor line-of-sight interference with the infra-red tracking mechanism when some lesions high on the dome of the liver were targeted. CONCLUSIONS The IVS significantly increased the accuracy of complex targeting procedures of phantom lesions and enhanced targeting in an eight-patient clinical pilot study. During the accrual phase of this pilot study, the development of improved non-optical tracking hardware obviated the requirement to maintain a direct line of sight. The trial was then halted prematurely in order to focus on the application of the IVS utilizing this non-optical modality.


Journal of Surgical Oncology | 2016

Multimodality treatment of intrahepatic cholangiocarcinoma: A review

Kerri A. Simo; Laura E. Halpin; Nicole M. McBrier; Jacob A. Hessey; E. Baker; Samuel W. Ross; Ryan Z. Swan; David A. Iannitti; John B. Martinie

Intrahepatic cholangiocarcinoma (iCCA) is the second most common primary hepatic cancer in the United States. Currently, curative treatment involves aggressive surgery. Chemotherapy and radiation treatments have been used for unresectable tumors with some success. Optimizing the use of current and developing novel multimodality treatment for iCCA is essential to improving outcomes. J. Surg. Oncol. 2016;113:62–83.


Journal of gastrointestinal oncology | 2015

Robotic pancreaticoduodenectomy for pancreatic adenocarcinoma: role in 2014 and beyond

Erin H. Baker; Samuel W. Ross; Ramanathan M. Seshadri; Ryan Z. Swan; David A. Iannitti; Dionisios Vrochides; John B. Martinie

Minimally invasive surgery (MIS) for pancreatic adenocarcinoma has found new avenues for performing pancreaticoduodenectomy (PD) procedures, a historically technically challenging operation. Multiple studies have found laparoscopic PD to be safe, with equivalent oncologic outcomes as compared to open PD. In addition, several series have described potential benefits to minimally invasive PD including fewer postoperative complications, shorter hospital length of stay, and decreased postoperative pain. Yet, despite these promising initial results, laparoscopic PDs have not become widely adopted by the surgical community. In fact, the vast majority of pancreatic resections performed in the United States are still performed in an open fashion, and there are only a handful of surgeons who actually perform purely laparoscopic PDs. On the other hand, robotic assisted surgery offers many technical advantages over laparoscopic surgery including high-definition, 3-D optics, enhanced suturing ability, and more degrees of freedom of movement by means of fully-wristed instruments. Similar to laparoscopic PD, there are now several case series that have demonstrated the feasibility and safety of robotic PD with seemingly equivalent short-term oncologic outcomes as compared to open technique. In addition, having the surgeon seated for the procedure with padded arm-rests, there is an ergonomic advantage of robotics over both open and laparoscopic approaches, where one has to stand up for prolonged periods of time. Future technologic innovations will likely focus on enhanced robotic capabilities to improve ease of use in the operating room. Last but not least, robotic assisted surgery training will continue to be a part of surgical education curriculum ensuring the increased use of this technology by future generations of surgeons.


Hpb | 2015

Laparoscopic microwave ablation of human liver tumours using a novel three-dimensional magnetic guidance system

David Sindram; Kerri A. Simo; Ryan Z. Swan; Sharif Razzaque; David J. Niemeyer; Ramanathan M. Seshadri; Erin M. Hanna; Iain H. McKillop; David A. Iannitti; John B. Martinie

BACKGROUND Accurate antenna placement is essential for effective microwave ablation (MWA) of lesions. Laparoscopic targeting is made particularly challenging in liver tumours by the needles trajectory as it passes through the abdominal wall into the liver. Previous optical three-dimensional guidance systems employing infrared technology have been limited by interference with the line of sight during procedures. OBJECTIVE The aim of this study was to evaluate a newly developed magnetic guidance system for laparoscopic MWA of liver tumours in a pilot study. METHODS Thirteen patients undergoing laparoscopic MWA of liver tumours gave consent to their participation in the study and were enrolled. Lesion targeting was performed using the InnerOptic AIM™ 3-D guidance system to track the real-time position and orientation of the antenna and ultrasound probe. RESULTS A total of 45 ablations were performed on 34 lesions. The median number of lesions per patient was two. The mean ± standard deviation lesion diameter was 18.0 ± 9.2 mm and the mean time to target acquisition was 3.5 min. The first-attempt success rate was 93%. There were no intraoperative or immediate postoperative complications. Over an average follow-up of 7.8 months, one patient was noted to have had an incomplete ablation, seven suffered regional recurrences, and five patients remained disease-free. CONCLUSIONS The AIM™ guidance system is an effective adjunct for laparoscopic ablation. It facilitates a high degree of accuracy and a good first-attempt success rate, and avoids the line of site interference associated with infrared systems.


Hpb | 2014

Survival analysis of patients with stage I and II hepatocellular carcinoma after a liver transplantation or liver resection

Ramanathan M. Seshadri; Siddesh Besur; David J. Niemeyer; Megan Templin; Iain H. McKillop; Ryan Z. Swan; John B. Martinie; Mark W. Russo; David A. Iannitti

INTRODUCTION Liver transplantation (LT) is a treatment option in select patients with hepatocellular carcinoma (HCC). The aim of the present study was to compare survival in Stage I or II HCC patients undergoing either liver transplant (LT) or a liver resection (LR). METHOD The study is a retrospective analysis of the National Cancer Data Base (1998-2011). In total, 148,882 patients with liver cancer were identified, of which 5-year survival data (1998-2006) were available for 64,227 patients. Patients were stratified by the American Joint Committee on Cancer (AJCC) clinical stage I and II. Kaplan-Meier curves and log-rank tests were used for statistical analysis. RESULTS 3340 HCC patients met analysis criteria. Among stage I HCC, 860 had LT and 871 had LR. Among stage II HCC, 833 had LT and 776 LR. In stage I patients the median survival for LT and LR were 127.9 and 56.7 months, respectively, (P < 0.0001) and in stage II patients the median survival was 110.8 and 42.8 months (P < 0.0001). Unlike LT patients, LR patients with Stage I HCC had a longer median survival compared with Stage II patients (P = 0.0002). CONCLUSION Liver transplantation offers a survival advantage compared with a liver resection among patients with Stage I and II HCC. LT is the best surgical treatment for early stage (I/II) HCC in patients with advanced fibrosis or cirrhosis, whereas LR provides equivalent outcomes to LT in patients without advanced fibrosis and should be considered as the first surgical option.


Hpb | 2013

Microwave ablation using 915-MHz and 2.45-GHz systems: what are the differences?

Kerri A. Simo; Victor B. Tsirline; David Sindram; Matthew T. McMillan; Kyle J. Thompson; Ryan Z. Swan; Iain H. McKillop; John B. Martinie; David A. Iannitti

OBJECTIVES This study was conducted to evaluate differences between 915-MHz and 2.45-GHz microwave ablation (MWA) systems in the ablation of hepatic tumours. METHODS A retrospective analysis of patients undergoing hepatic tumour MWA utilizing two different systems over a 10-month period was carried out. RESULTS Data for a total of 48 patients with a mean age of 58 ± 1.24 years were analysed. A total of 124 tumours were ablated; 72 tumours were ablated with a 915-MHz system and 52 with a 2.45-GHz system. Mean tumour diameters were 1.7 ± 0.1 cm in the 915-MHz group and 2.5 ± 0.2 cm in the 2.45-GHz group (P < 0.01). Mean ablation time per burn was 8.1 ± 0.3 min in the 915-MHz group and 4.0 ± 0.1 min in the 2.45-GHz group (P < 0.01). The mean number of burns per lesion was 2.0 ± 0.1 in the 915-MHz group and 1.7 ± 0.1 in the 2.45-GHz group (P < 0.05). The mean ablation time per lesion was 9.7 ± 0.7 min in the 915-MHz group, and 6.6 ± 0.6 min in the 2.45-GHz group (P < 0.01). The 2.45-GHz system demonstrated a better correlation between ablation time and tumour size (r(2) = 0.6222) than the 915-MHz system; (r(2) = 0.0696). Mean total energy applied per lesion, and energy applied per cm, were greater with the 915-MHz system (P < 0.05 and P < 0.01, respectively). Total energy applied per lesion was similarly correlated for the 2.45-GHz (r(2) = 0.6263) and 915-MHz (r(2) = 0.7012) systems. Mean total energy applied per cm/min was greater with the 2.45-GHz system (P < 0.05). CONCLUSIONS Both 915-MHz and 2.45-GHz MWA systems achieve reproducible hepatic tumour ablation. The 2.45-GHz system achieves equivalent, but more predictable and faster ablations using a single antenna system.


Journal of Gastrointestinal Surgery | 2012

Pyogenic Hepatic Abscess Secondary to Endolumenal Perforation of an Ingested Foreign Body

Wesley A. Glick; Kerri A. Simo; Ryan Z. Swan; David Sindram; David A. Iannitti; John B. Martinie

IntroductionPyogenic hepatic abscess induced by foreign body perforation of the gastrointestinal tract is an increasing phenomenon. Pyogenic liver abscess in itself is a challenge to treat without the complication of a foreign body.MethodsA case of a patient who developed a pyogenic hepatic abscess after unknown ingestion of a toothpick that subsequently perforated the duodenum is presented, and a literature review of pyogenic hepatic abscesses secondary to ingestion of foreign bodies and their causes, diagnosis, and treatment was performed.DiscussionEven with a thorough workup, often the diagnosis of a pyogenic hepatic abscess secondary to an endolumenal foreign body perforation is not obtained until the time of operation.


Langenbeck's Archives of Surgery | 2014

Fibrin sealants and topical agents in hepatobiliary and pancreatic surgery: a critical appraisal

Erin M. Hanna; John B. Martinie; Ryan Z. Swan; David A. Iannitti

IntroductionFibrin sealants and topical hemostatic agents have been used extensively in hepatobiliary and pancreatic (HPB) surgery to promote coagulation and clot formation decreasing the need for allogeneic blood transfusion and to act as tissue sealants, ideally preventing biliary, enteric, and pancreatic leaks.ResultsCurrent literature has demonstrated some favorable outcomes using many different products for application in the field of HPB surgery. However, critical findings exist demonstrating lack of reproducible efficacy or benefit. In all, many clinical trials have demonstrated effectiveness of fibrin sealants and other agents at reducing the need for intraoperative and postoperative blood transfusion. Ability to effectively seal tissues providing biliostatic effect or preventing postoperative fistula formation remains debated as definitive evidence is lacking.ConclusionsIn the following invited review, we discuss current literature describing the use of topical agents and fibrin sealants in liver and pancreas surgery. We summarize major contemporary clinical trials and their findings regarding the use of these agents in HPB surgery and provide evidence from the preclinical literature as to the translation of these products into the clinical arena.

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David Sindram

Carolinas Medical Center

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E. Baker

Carolinas Medical Center

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Kerri A. Simo

Carolinas Medical Center

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