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Dive into the research topics where Jonathan M. Lorenz is active.

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Featured researches published by Jonathan M. Lorenz.


Pediatric Transplantation | 2012

Portal Hypertension in Children: Expert Pediatric Opinion on the Report of the Baveno V Consensus Workshop on Methodology of Diagnosis and Therapy in Portal Hypertension

Benjamin L. Shneider; Jaime Bosch; Roberto de Franchis; Sukru Emre; Roberto J. Groszmann; Simon C. Ling; Jonathan M. Lorenz; Robert H. Squires; Riccardo A. Superina; Ann E. Thompson; George V. Mazariegos

Shneider BL, Bosch J, de Franchis R, Emre SH, Groszmann RJ, Ling SC, Lorenz JM, Squires RH, Superina RA, Thompson AE, Mazariegos GV. Portal Hypertension in Children: Expert Pediatric Opinion on the Report of the Baveno V Consensus Workshop on Methodology of Diagnosis and Therapy in Portal Hypertension.


Journal of Vascular and Interventional Radiology | 1999

Angioplasty and Bolus Urokinase Infusion for the Restoration of Function in Thrombosed Brescia-Cimino Dialysis Fistulas

George X. Zaleski; Brian Funaki; Shawn Kenney; Jonathan M. Lorenz; R S Garofalo

PURPOSE To evaluate the use of urokinase and angioplasty in treatment of thrombosed Brescia-Cimino fistulas. MATERIALS AND METHODS From January 1994 to April 1997, 17 patients (10 women and seven men; age range, 17-78 years; mean 54 years) with complete thrombosis of their Brescia-Cimino fistulas were referred to our department for thrombolysis and angioplasty. Thrombosis of the fistula had occurred within 24 hours of attempted thrombolysis in 11 patients and between 24 and 72 hours in six patients. Urokinase was given as a bolus into the fistula, and heparin was administered into the central venous vasculature. Angioplasty was performed at the arterial inflow and the fistula itself. RESULTS Procedural success was 82% (14 of 17 patients). Primary patency was 71% at 6 months and 64% at 12 months. Primary assisted patency was 93% at 6 and 12 months. Secondary patency was 100% at 6 and 12 months. One fistula thrombosed within 24 hours of the initial procedure, and a repeat procedure was successfully performed. All other fistulas have remained patent with a maximum follow-up of 40 months (average function of 16 months). Two patients have died of unrelated causes. One Wallstent was deployed for treatment of an angioplasty-induced venous rupture. CONCLUSION Long-term function of Brescia-Cimino fistulas after thrombolysis and angioplasty is excellent with patency rates similar to those of newly placed, mature Brescia-Cimino fistulas.


CardioVascular and Interventional Radiology | 2008

Use of Retrievable Compared to Permanent Inferior Vena Cava Filters: A Single-Institution Experience

Thuong G. Van Ha; Andy S. Chien; Brian Funaki; Jonathan M. Lorenz; Giancarlo Piano; Maxine Shen; Jeffrey A. Leef

The purpose of this study was to review the use, safety, and efficacy of retrievable inferior vena cava (IVC) filters in their first 5 years of availability at our institution. Comparison was made with permanent filters placed in the same period. A retrospective review of IVC filter implantations was performed from September, 1999, to September, 2004, in our department. These included both retrievable and permanent filters. The Recovery nitinol and Günther tulip filters were used as retrievable filters. The frequency of retrievable filter used was calculated. Clinical data and technical data related to filter placement were reviewed. Outcomes, including pulmonary embolism, complications associated with placement, retrieval, or indwelling, were calculated. During the study period, 604 IVC filters were placed. Of these, 97 retrievable filters (16%) were placed in 96 patients. There were 53 Recovery filter and 44 Tulip filter insertions. Subjects were 59 women and 37 men; the mean age was 52 years, with a range of from 18 to 97 years. The placement of retrievable filters increased from 2% in year 1 to 32% in year 5 of the study period. The total implantation time for the permanent group was 145,450 days, with an average of 288 days (range, 33–1811 days). For the retrievable group, the total implantation time was 21,671 days, with an average of 226 days (range, 2–1217 days). Of 29 patients who returned for filter retrieval, the filter was successfully removed in 28. There were 14 of 14 successful Tulip filter retrievals and 14 of 15 successful Recovery filter retrievals. In one patient, after an indwelling period of 39 days, a Recovery nitinol filter could not be removed secondary to a large clot burden within the filter. For the filters that were removed, the mean dwell time was 50 days for the Tulip type and 20 days for the Recovery type. Over the follow-up period there was an overall PE incidence of 1.4% for the permanent group and 1% for the retrieval group. In conclusion, there was an increase in the use of retrievable filters over the study period and an overall increase in the total number of filters implanted. The increased use of these filters appeared to be due to expanded indications predicated by their retrievability. Placement and retrieval of these filters have a low risk of complications, and retrievable filters appeared effective, as there was low rate of clinically significant pulmonary embolism associated with these filters during their indwelling time.


CardioVascular and Interventional Radiology | 2006

Transjugular Intrahepatic Portosystemic Shunt Placement in Patients with Cirrhosis and Concomitant Portal Vein Thrombosis

Thuong G. Van Ha; Justin Hodge; Brian Funaki; Jonathan M. Lorenz; Jordan D. Rosenblum; Christopher Straus; Jeff Leef

PurposeTo determine the safety and efficacy of transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with liver cirrhosis complicated by thrombosed portal vein.MethodsThis study reviewed 15 cases of TIPS creation in 15 cirrhotic patients with portal vein thrombosis at our institution over an 8-year period. There were 2 women and 13 men with a mean age of 53 years. Indications were refractory ascites, variceal hemorrhage, and refractory pleural effusion. Clinical follow-up was performed in all patients.ResultsThe technical success rate was 75% (3/4) in patients with chronic portal vein thrombosis associated with cavernomatous transformation and 91% (10/11) in patients with acute thrombosis or partial thrombosis, giving an overall success rate of 87%. Complications included postprocedural encephalopathy and localized hematoma at the access site. In patients with successful shunt placement, the total follow-up time was 223 months. The 30-day mortality rate was 13%. Two patients underwent liver transplantation at 35 days and 7 months, respectively, after TIPS insertion. One patient had an occluded shunt at 4 months with an unsuccessful revision. The remaining patients had functioning shunts at follow-up.ConclusionTIPS creation in thrombosed portal vein is possible and might be a treatment option in certain patients.


Journal of Vascular and Interventional Radiology | 2009

Techniques Used for Difficult Retrievals of the Günther Tulip Inferior Vena Cava Filter: Experience in 32 Patients

Thuong G. Van Ha; Olga Vinokur; Jonathan M. Lorenz; Sidney Regalado; Steven M. Zangan; Giancarlo Piano; Brian Funaki

PURPOSE To retrospectively review experience with difficult retrievals of Günther Tulip filters (GTFs) in which various techniques were used. MATERIALS AND METHODS From December 2004 to December 2006, 32 patients were referred to a single radiology department for GTF retrieval (25 women and seven men; mean age, 40 years; range, 21-60 y). All patients were evaluated, and 22 of these patients had undergone unsuccessful filter retrieval attempts elsewhere. In the remaining patients, significant tilt of the filter (n = 8) or difficult internal jugular vein access (n = 2) discouraged retrieval attempts. There were a total of 38 filters. Twenty-five patients had a filter in the infrarenal inferior vena cava (IVC). Among the remaining seven patients, six had bilateral iliac filters and one had a left iliac filter. Retrievals were performed via conventional technique-ie, by snaring the hook of the filter without additional maneuvers-or other techniques. RESULTS Thirty-seven of 38 filters were successfully removed, for a success rate of 97%. Successful retrievals were performed with conventional (n = 4), catheter twist (n = 3), modified snare (n = 15), loop snare (n = 14), and balloon dilation (n = 1) techniques. The average dwell time for filters successfully removed was 58 days (range, 22-258 d). One failure occurred in a patient who had undergone unsuccessful retrieval previously. The hook of the filter and a displaced secondary strut, which had migrated superiorly, were incorporated into the IVC wall in this case. CONCLUSIONS Additional maneuvers were useful in these difficult retrievals of GTFs that might not otherwise be retrievable with the conventional method.


Journal of Vascular and Interventional Radiology | 2006

Percutaneous Treatment of Venous Outflow Obstruction in Pediatric Liver Transplants

Jonathan M. Lorenz; Thuong G. Van Ha; Brian Funaki; Michael B. Millis; Jeffrey A. Leef; Andrew Bennett; Jordan D. Rosenblum

PURPOSE To evaluate the efficacy and safety of percutaneous dilation in the treatment of impaired venous outflow in pediatric patients with liver transplants. MATERIALS AND METHODS Review was undertaken of the records of 35 procedures to dilate impaired venous outflow in 16 consecutive children (aged 11 days to 17.8 years; mean, 7.2 +/- 5.8 y) after liver transplantation over a period of 8 years. Patients presented clinically with signs or symptoms of obstruction of the hepatic venous or inferior vena cava anastomosis and/or abnormal noninvasive imaging findings and were referred primarily to the interventional radiology department for treatment. None were excluded. Technical and clinical success rates were calculated. After venoplasty, patients with incomplete venographic resolution or pressure gradients exceeding 5 mm Hg were treated with stents. Seven died or required repeat transplantation during the study period for reasons unrelated to venous outflow obstruction. Patency rates were calculated for all other patients with sufficient follow-up in the pediatric hepatology clinic. RESULTS The combined technical success rate for venoplasty (12 of 16) and stent placement (three of 16) was 94% (15 of 16), and the clinical success rate was 81% (13 of 16). One minor complication occurred: a transient hypoxic episode. Primary patency rates were 72.7% (eight of 11) at 3 months, 60% (six of 10) at 6 months, 55.6% (five of nine) at 12 months, 50% (four of eight) at 18 months, and 50% (three of six) at 36 months. Primary assisted and secondary patency rates were 90.9% (10 of 11) at 3 months, 90% (nine of 10) at 6 months, 88.9% (eight of nine) at 12 months, 87.5% (seven of eight) at 18 months, and 83.3% (five of six) at 36 months. CONCLUSIONS Excellent technical and clinical success rates can be achieved with percutaneous dilation of impaired venous outflow after pediatric liver transplantation. Long-term patency may require repeated interventions.


Journal of Vascular and Interventional Radiology | 2012

Evaluation and Treatment of Suspected Type II Endoleaks in Patients with Enlarging Abdominal Aortic Aneurysms

Brian Funaki; Nour Birouti; Steven M. Zangan; Thuong G. Van Ha; Jonathan M. Lorenz; Rakesh Navuluri; Christopher L. Skelly; Jeffrey A. Leef

PURPOSE To evaluate angiographic diagnosis and embolotherapy of patients with enlarging abdominal aortic aneurysms and computed tomographic (CT) diagnosis of type II endoleak. MATERIALS AND METHODS A retrospective review was performed of all patients referred to a single vascular and interventional radiology section from January 1, 2003, to June 1, 2011, with a diagnosis of enlarging aneurysm and type II endoleak. Twenty-five patients underwent 40 procedures between 12 and 82 months after endograft insertion (mean, 48 mo) for diagnosis and/or treatment of endoleaks. RESULTS Type II endoleaks were treated with cyanoacrylate, coils, and ethylene vinyl alcohol copolymer in 16 patients. Technical success rate was 88% (14 of 16 patients) and clinical success rate was 100% (16 of 16 patients). Aneurysm growth was arrested in all cases over a mean follow-up of 27.5 months (range, 6-88 mo). Endoleaks in nine patients were misclassified on CT; two had type I endoleaks and seven had type III endoleaks. Four of the nine patients (two type I endoleaks and two type III endoleaks) were correctly classified after initial angiography. The other five type III endoleaks were correctly classified on CT after coil embolization of the inferior mesenteric artery. Direct embolization was performed via sac puncture with ethylene vinyl alcohol copolymer in two of the latter five patients and eliminated endoleaks in both. CONCLUSIONS Aneurysm growth caused by type II endoleaks was arrested by embolization. CT misclassification occurred relatively commonly; type III endoleaks purported to be type II endoleaks were found in 28% of patients (seven of 25).


Seminars in Interventional Radiology | 2006

Complications of Percutaneous Fluid Drainage

Jonathan M. Lorenz; Jamie Lee Thomas

Percutaneous abscess drainage is one of the most common and rewarding procedures performed by interventional radiologists. Technical success is immediately apparent by aspiration of purulent contents and is nearly always achieved, with rates exceeding 90% in most literature studies. Clinical success is typical even for many abscesses colonized with multidrug-resistant organisms. In patients presenting with sepsis, this procedure offers an immediate and minimally invasive solution to a life-threatening condition, often resulting in defervescence and restoration of hemodynamic stability within 1 to 2 days. Although complications of abscess drainage are uncommon, radiologists should be able to recognize and treat all adverse sequelae discussed in this article.


Techniques in Vascular and Interventional Radiology | 2008

Placement of Transjugular Intrahepatic Portosystemic Shunts in Children

Jonathan M. Lorenz

Performance of transjugular intrahepatic portosystemic shunting (TIPS) in children requires an awareness of the technical challenges posed by pediatric anatomy and physiology. Any interventional radiologist skilled in adult TIPS and contemplating performing their first pediatric TIPS should consider adding a second set of more experienced hands. This article reviews some of the more salient technical considerations for performing TIPS in this unique patient population.


Journal of Vascular and Interventional Radiology | 2005

Removal of Günther Tulip Vena Cava Filter through Femoral Vein Approach

Thuong G. Van Ha; Darius Keblinskas; Brian Funaki; Jonathan M. Lorenz

The Günther Tulip vena cava filter is designed for removal by the internal jugular vein approach with use of a blunted hook placed at the superior aspect of the filter. Removal of this filter was performed by the femoral approach in a patient with central venous occlusion that precluded removal by the conventional approach.

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