Theoretical Basis for Controlling Minimal Tumor Temperature During Interstitial Conductive Heat Therapy

This paper describes simulation of steady-state intratumoral temperatures achieved by a simple modality of local heat therapy: interstitial treatment with parallel arrays of warmed, conductive heating elements. During “conductive heating” power is directly deposited only in the interstitial probes. Adjacent tissue is warmed by heat conduction. Simulations of interstitial conductive heating involved solution of the bioheat transfer equation on a digital computer using a finite difference model of the treated tissue. The simulations suggest that when the complete temperature distributions for conductive interstitial hyperthermia are examined in detail, substantial uniformity of the temperature distributions is evident. Except for a thin sleeve of tissue surrounding each heating element, a broad, flat central valley of temperature elevation is achieved, with a well defined minimum temperature, very close to modal and median tissue temperatures. Because probes are inserted directly in tumor tissue, the thin sleeve of overheated tissue would not be expected to cause normal tissue complications. The temperature of the heated probes must be continuously controlled and increased in the face of increased blood flow in order to maintain minimum tumor temperature. However, correction for changes in blood flow is possible by adjusting probe temperature according to a feedback control scheme, in which power dissipation from each probe is the sensed input variable. Conductive interstitial heating with continually controlled probe temperature deserves investigation as a technique for local hyperthermia therapy

Transcatheter placement of a low-profile biodegradable pulmonary valve made of small intestinal submucosa: A long-term study in a swine model

ObjectiveWe sought to investigate a placement of a percutaneous low-profile prosthetic valve constructed of small intestinal submucosa in the pulmonary position in a swine model.MethodsTwelve female farm pigs were stented at the native pulmonary valve to induce pulmonary insufficiency. Once right ventricular dilation occurred, the small intestinal submucosa valve was implanted. The pigs were followed up with transthoracic echocardiographic Doppler scanning. One animal died of heart failure before valve replacement. Animals were euthanized at 1 day, 1 month, 3 months, 6 months, and 12 months after valve implantation.ResultsThe small intestinal submucosa pulmonary valve showed effective reversal of pulmonary regurgitation. There were no misplacements during deployment. There were no embolizations. One-year echocardiographic follow-up showed minimal regurgitation and no stenosis for a valve/vessel ratio of 0.78 or greater. Histologic examination demonstrated intensive remodeling of the small intestinal submucosal valve. Within 1 month, the surface was covered by endothelium, and fibroblasts invaded the interior. Over the following months, the small intestinal submucosal valve remodeled without apparent graft rejection.ConclusionThe small intestinal submucosa valve has the potential for graft longevity without the need for anticoagulation or immunosuppression. Histologic remodeling of the valve tissue provides a replacement capable of resembling a native valve that can be placed percutaneously with low-profile delivery systems

Clinical feasibility of umbilical cord tissue-derived mesenchymal stem cells in the treatment of multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a progressively debilitating neurological condition in which the immune system abnormally erodes the myelin sheath insulating the nerves. Mesenchymal stem cells (MSC) have been used in the last decade to safely treat certain immune and inflammatory conditions. METHODS: A safety and feasibility study was completed on the use of umbilical cord MSC (UCMSC) as a treatment for MS. In this 1-year study, consenting subjects received seven intravenous infusions of 20 × 10 RESULTS: Twenty subjects were enrolled in this study. No serious adverse events were reported. Of the mild AEs denoted as possibly related to treatment, most were headache or fatigue. Symptom improvements were most notable 1 month after treatment. Improvements were seen in EDSS scores (p \u3c 0.03), as well as in bladder, bowel, and sexual dysfunction (p \u3c 0.01), in non-dominant hand average scores (p \u3c 0.01), in walk times (p \u3c 0.02) and general perspective of a positive health change and improved quality of life. MRI scans of the brain and the cervical spinal cord showed inactive lesions in 15/18 (83.3%) subjects after 1 year. CONCLUSIONS: Treatment with UCMSC intravenous infusions for subjects with MS is safe, and potential therapeutic benefits should be further investigated. Trial registration ClinicalTrials.gov NCT02034188. Registered Jan 13, 2014. https://clinicaltrials.gov/ct2/show/NCT02034188

DYNAMIC IMAGING OF THE DOG HEART FROM THE ESOPHAGUS USING ULTRASOUND

The purpose of this research was to obtain a new ultrasonic view of the heart using the esophageal approach. More specifically it was to propose, design and build an esophageal scanner, to evaluate its performance, and to determine the clinical potential of the esophageal images. The research therefore encompasses the development of both a new device and a new method of imaging the heart. The new transesophageal ultrasonic sector scanner produces high quality, real-time images of the major cardiac structures. The device consists of an esophageal probe with rotating transducers, electronic circuitry to produce the desired image formats, and video processing circuitry to improve the quality of the image. The esophageal probe consists of four 5-MHz PZT-5 piezoelements of 6.35 mm diameter mounted at 90-degree centers on a shaft that rotates at 900 rpm. Optical position sensing is used to reduce the transducer error to less than one degree. The piezoelements are pulsed at a 5 kHz rate and the echoes are processed electronically. Sixty images per second are displayed in an 83-degree sector on the gray scale CRT and recorded on standard videotape for review. By interactive positioning of the esophageal probe, heart ventricles, atria, and valves can be visualized and their dynamics can be studied. In addition to the sector display format, A-mode and M-mode display formats are produced. The performance of the scanner was measured and is reported herein. The dog was chosen as a cardiovascular model for this research. Images were obtained from anesthetized dogs to exhibit the basic properties of transesophageal imaging. Eight anatomical cross sections of the canine heart at one-centimeter intervals measured from the apex of the heart were prepared. Images, obtained in these planes, were compared with the cross sections. Basic cardiac structures visible in the images are described. Contrast media was injected to examine wall movement and blood flow through the cardiac system. Time-sequenced images throughout the cardiac cycle are presented. We have shown the feasibility of the transesophageal approach. High quality images of major cardiac structures are obtained using this method. The restrictions, encountered when imaging from the chest, are overcome by imaging from the esophagus, and therefore, an unrestricted view of the heart is available

Zenith abdominal aortic aneurysm endovascular graft

PurposeThe safety and efficacy of the Zenith (Cook Inc, Bloomington, Ind) endovascular graft was assessed based on the United States multicenter trial through 5 years of follow-up.MethodsBetween 2000 and 2003, the pivotal study enrolled patients to open surgery (control) or the Zenith endovascular graft (endovascular). A separate continued access study arm enrolled endovascular patients using the same inclusion/exclusion criteria. Both studies were designed for 2-year follow-up, and the pivotal endovascular patients had the option of extending the study follow-up through 5 years. All endovascular patients were stratified by physiologic risk into high-risk and standard-risk groups to assess overall mortality, rupture, conversion, endoleaks, secondary interventions, and sac enlargement. The entire endovascular cohort was pooled to assess device integrity, limb occlusion, component separation, and migration. The suboptimal endovascular result (SER) was established as an end point to assess late adverse outcomes. Statistical analyses included Kaplan-Meier estimations and Cox regression to assess factors contributing to sac enlargement and SER.ResultsThe study enrolled 739 endovascular patients (352 pivotal, 387 continued access); 158 patients in the pivotal study reconsented to be followed up for 5 years. For the patients at standard and high risk at 5 years, the respective survival estimate was 83% and 61%, aneurysm-related death was 2% and 4%, and freedom from rupture was 100% and 99.6%, respectively. Cumulative risk of conversion, limb occlusion, migration >10 mm, or component separation was ≤3% at 5 years. Cumulative risk of late endoleak was 12% to 15%, representing the primary indication for secondary interventions which occurred in 20% of standard-risk patients and 25% of high-risk patients through 5 years. Sac enlargement was very rare and associated with advanced age and larger aneurysms. SER was predicted by advanced age and internal iliac artery occlusion.ConclusionThese middle- and long-term data support long-term durability of the Zenith endovascular graft. Risk of aneurysm-related death or rupture was exceptionally low, and complications of migration, limb occlusion, and device integrity issues were uncommon. Incidence of late endoleaks and association of endoleaks with sac growth underscore the need for long-term follow-up of patients treated with endovascular grafts, although the sequelae of such events are unknown