Anna R. Graham

Closed chest catheter desiccation of the atrioventricular junction using radiofrequency energy—A new method of catheter ablation

Closed chest catheter ablation of the atrioventricular (AV) junction has been performed with direct current or laser energy. The effect of 750 kHz radiofrequency energy on ablation of the AV junction was evaluated in 13 dogs. The radiofrequency energy was generated from an electrosurgical generator in the bipolar mode. The radiofrequency output was delivered between two distal electrodes (bipolar ablation) in eight dogs, and between the distal electrode and an external patch electrode (unipolar ablation) in another five dogs at varying power (watts) but with a constant pulse duration of 10 seconds. Complete AV block was achieved in 11 dogs and second degree AV block in 2. During the 4 to 7 day follow-up period, complete AV block persisted in 9 of the 11 dogs with initial complete heart block. The other two had return of AV conduction; one had persistent 2:1 AV block and the other had persistent first degree AV block. Of the two dogs with initial second degree AV block, one developed complete AV block, the other had resumption of 1:1 AV conduction with a normal PR interval. Energy was delivered in 1 to 13 applications per dog. One hundred to 700 J per application was delivered with bipolar ablation and 10 to 100 J with unipolar ablation. There was no damage to the catheter unless the catheter was repeatedly used in excess of 1,500 J of total energy. Ventricular arrhythmias were not observed. Pathologic examination showed well delineated coagulation necrosis at the AV junction without surrounding hemorrhage or mural thrombus. Microscopic findings consisted of necrosis with cell infiltration in the periphery of necrosis. Most injuries involved the AV node, the approaches to the AV node and the penetrating bundle. In conclusion, catheter ablation of the AV junction with radiofrequency energy is safe. It can effectively induce discrete areas of necrosis and produce various degrees of AV block. In addition, ablation by radiofrequency energy has distinct advantages as compared with catheter ablation with direct current or laser energy.

Overview of telepathology, virtual microscopy, and whole slide imaging: prospects for the future ☆

Telepathology, the practice of pathology at a long distance, has advanced continuously since 1986. Today, fourth-generation telepathology systems, so-called virtual slide telepathology systems, are being used for education applications. Both conventional and innovative surgical pathology diagnostic services are being designed and implemented as well. The technology has been commercialized by more than 30 companies in Asia, the United States, and Europe. Early adopters of telepathology have been laboratories with special challenges in providing anatomic pathology services, ranging from the need to provide anatomic pathology services at great distances to the use of the technology to increase efficiency of services between hospitals less than a mile apart. As to what often happens in medicine, early adopters of new technologies are professionals who create model programs that are successful and then stimulate the creation of infrastructure (ie, reimbursement, telecommunications, information technologies, and so on) that forms the platforms for entry of later, mainstream, adopters. The trend at medical schools, in the United States, is to go entirely digital for their pathology courses, discarding their student light microscopes, and building virtual slide laboratories. This may create a generation of pathology trainees who prefer digital pathology imaging over the traditional hands-on light microscopy. The creation of standards for virtual slide telepathology is early in its development but accelerating. The field of telepathology has now reached a tipping point at which major corporations now investing in the technology will insist that standards be created for pathology digital imaging as a value added business proposition. A key to success in teleradiology, already a growth industry, has been the implementation of standards for digital radiology imaging. Telepathology is already the enabling technology for new, innovative laboratory services. Examples include STAT QA surgical pathology second opinions at a distance and a telehealth-enabled rapid breast care service. The innovative bundling of telemammography, telepathology, and teleoncology services may represent a new paradigm in breast care that helps address the serious issue of fragmentation of breast cancer care in the United States and elsewhere. Legal and regulatory issues in telepathology are being addressed and are regarded as a potential catalyst for the next wave of telepathology advances, applications, and implementations.

Bone marrow edema pattern in advanced hip osteoarthritis: quantitative assessment with magnetic resonance imaging and correlation with clinical examination, radiographic findings, and histopathology.

ObjectiveTo correlate the amount of bone marrow edema (BME) calculated by magnetic resonance imaging(MRI) with clinical findings, histopathology, and radiographic findings, in patients with advanced hip osteoarthritis(OA).Materials and methodsThe study was approved by The Institutional Human Subject Protection Committee. Coronal MRI of hips was acquired in 19 patients who underwent hip replacement. A spin echo (SE) sequence with four echoes and separate fast spin echo (FSE) proton density (PD)-weighted SE sequences of fat (F) and water (W) were acquired with water and fat suppression, respectively. T2 and water:fat ratio calculations were made for the outlined regions of interest. The calculated MRI values were correlated with the clinical, radiographic, and histopathologic findings.ResultsAnalyses of variance were done on the MRI data for W/(W + F) and for T2 values (total and focal values) for the symptomatic and contralateral hips. The values were significantly higher in the study group. Statistically significant correlations were found between pain and total W/(W + F), pain and focal T2 values, and the number of microfractures and calculated BME for the focal W/(W + F) in the proximal femora. Statistically significant correlations were found between the radiographic findings and MRI values for total W/(W + F), focal W/(W + F) and focal T2 and among the radiographic findings, pain, and hip movement. On histopathology, only a small amount of BME was seen in eight proximal femora.ConclusionThe amount of BME in the OA hip, as measured by MRI, correlates with the severity of pain, radiographic findings, and number of microfractures.

Imaging of musculoskeletal soft tissue infections

Prompt and appropriate imaging work-up of the various musculoskeletal soft tissue infections aids early diagnosis and treatment and decreases the risk of complications resulting from misdiagnosis or delayed diagnosis. The signs and symptoms of musculoskeletal soft tissue infections can be nonspecific, making it clinically difficult to distinguish between disease processes and the extent of disease. Magnetic resonance imaging (MRI) is the imaging modality of choice in the evaluation of soft tissue infections. Computed tomography (CT), ultrasound, radiography and nuclear medicine studies are considered ancillary. This manuscript illustrates representative images of superficial and deep soft tissue infections such as infectious cellulitis, superficial and deep fasciitis, including the necrotizing fasciitis, pyomyositis/soft tissue abscess, septic bursitis and tenosynovitis on different imaging modalities, with emphasis on MRI. Typical histopathologic findings of soft tissue infections are also presented. The imaging approach described in the manuscript is based on relevant literature and authors’ personal experience and everyday practice.

Radiofrequency Catheter Ablation of the Left and Right Ventricles: Anatomic and Electrophysiologic Observations

Certain untoward effects associated with the use of direct‐current electrical catheter ablation of the ventricular endomyocardium have been noted. We assessed the efficacy and safety of closed‐chest catheter ablation of the left and right ventricles using radio frequency (RF) energy (750 kHz) in six dogs. Mean HF energies between 93 and 123 joules (J) were randomly delivered to three left ventricular (LV) sites via two distal adjacent electrodes (bipolar configuration) using 6–7F USCI tripolar or quadripolar catheters with an interelectrode distance of 5–10 mm. Another 90–143 J were given to two right ventricular (RV) sites in single or multiple divided applications between a distal electrode and an external patch electrode (unipolar configuration). Ventricular arrhythmias were not observed during application of RF energy. Programmed ventricular stimulation before and after the procedure did not induce ventricular tachycardia (VT) or fibrillation except in one dog who had inducible VT prior to ablation. There were no significant changes in LV and RV elective refractory periods after the procedures. Occasional premature ventricular beats and rare episodes of non‐sustained VT (3–12 beats) were observed in ambulatory electrocardiographic recordings (13–24 hrs) done immediately after ablation. Dogs were sacrificed after 4–5 days. Pathology showed well‐demarcated round or ovoid lesions of varying sizes, Murai thrombus was found in one dog. Microscopic findings consisted of circumscribed areas of coagulation necrosis with a peripheral zone of cellular infiltration. Transmural necrosis without perforation was occasionally seen in the thin RV wall when higher energies were delivered. In conclusion, discrete areas of desiccation injury in the ventricles can be achieved by transcatheter bipolar or unipolar ablation using RF energy. The complications associated with this method appear to be minimal. Further experiments are needed to evaluate its potential for catheter ablation of ventricular tachycardia.

Determinants of Impedance Rise During Catheter Ablation of Bovine Myocardium with Radiofrequency Energy

Recently, radiofrequency (RF) energy has been used as an alternative energy source to direct‐current (DC) electricity for catheter ablation of recurrent tachyarrhythmias. Since delivered energy is inversely related to impedance, factors that cause impedance rise during catheter ablation impede the ability to ablate tissue. To elucidate some of the factors responsible for impedance rise during RF (750 kHz) catheter ablation using a constant voltage RF generator, the effects of the following variables on impedance were studied in an in vitro bovine heart model: power setting (10–70 W), pulse duration (10–60 sec), catheter contact pressure (5‐1 20 gm), repeated applications (2–4), and immersion media (saline vs citrated blood). Baseline impedance in blood was twice that of saline (190 vs 80 ohm) and rises in impedances occurred more rapidly in blood for the same energy settings. Increased power settings (≥ 30 W) and pulse duration (≥ 30 sec at 20 W) were associated with impedance rises in blood medium. Typically, impedance rises in blood were associated with blood coagulum on the catheter electrodes. Impedance rises in both saline and blood media were also associated with tissue charring and endocardial surface disruption. Once a rise in impedance occurred at the ablation site, repeated applications to the same site resulted in a more rapid rise in impedance. Catheter contact pressure of 80 gm or more also resulted in rapid impedance rise. These data suggest that factors other than set power and duration may also contribute to impedance rises during RF ablation. These Endings may have important clinical implications in performing catheter ablation with RF energy.

Comparison of catheter ablation using radiofrequency versus direct current energy: Biophysical, electrophysioiogic and pathologic observations☆

The effects of catheter ablation with radiofrequency versus direct current energy were compared in 18 dogs assigned to two groups (of 9 dogs each). Each dog underwent a single ablation at two sites in the left ventricle at energy levels of 100, 200 or 300 J delivered in unipolar configuration to six dogs each. A transient decrease in left ventricular systolic pressure (from 121.3 +/- 24.5 to 94.2 +/- 18.7 mm Hg, p less than 0.01) and wall motion abnormality were noted in dogs with direct current shock. The left ventricular ejection fraction decreased (from 50 +/- 2% to 34 +/- 3%, p less than 0.001) shortly after direct current ablation but improved 4 weeks later to 43 +/- 3%. There were no significant changes in left ventricular pressure, wall motion or ejection fraction in dogs in the radiofrequency ablation group. Sustained ventricular tachycardia (greater than or equal to 30 s) was seen immediately after direct current shock in all dogs, and one dog died of intractable ventricular fibrillation. A 24-h ambulatory electrocardiographic (ECG) monitor obtained immediately after the procedure showed multiple runs of ventricular tachycardia in all dogs exposed to direct current ablation but in only three dogs that underwent radiofrequency ablation. No differences were found in peak creatine kinase, complete blood count with smear and B-beta 15-42 fibrinopeptide levels. Pathologically, direct current-induced lesions were larger (mean length x width x depth 10.9 x 7.5 x 5.2 vs. 4.8 x 4.6 x 4.3 mm) and were poorly circumscribed with inhomogeneous margins of necrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Virtual slide telepathology enables an innovative telehealth rapid breast care clinic

An innovative telemedicine-enabled rapid breast care service is described that bundles telemammography, telepathology, and teleoncology services into a single day process. The service is called the UltraClinics Process. Because the core services are at 4 different physical locations, a challenge has been to obtain stat second opinion readouts on newly diagnosed breast cancer cases. To provide same day quality assurance rereview of breast surgical pathology cases, a DMetrix DX-40 ultrarapid virtual slide scanner (DMetrix Inc, Tucson, AZ) was installed at the participating laboratory. Glass slides of breast cancer and breast hyperplasia cases were scanned the same day the slides were produced by the University Physicians Healthcare Hospital histology laboratory. Virtual slide telepathology was used for stat quality assurance readouts at University Medical Center, 6 miles away. There was complete concurrence with the primary diagnosis in 139 (90.3%) of cases. There were 4 (2.3%) major discrepancies, which would have resulted in a different therapy and 3 (1.9%) minor discrepancies. Three cases (1.9%) were deferred for immunohistochemistry. In 2 cases (1.3%), the case was deferred for examination of the glass slides by the reviewing pathologists at University Medical Center. We conclude that the virtual slide telepathology quality assurance program found a small number of significant diagnostic discrepancies. The virtual slide telepathology program service increased the job satisfaction of subspecialty pathologists without special training in breast pathology, assigned to cover the general surgical pathology service at a small satellite university hospital.

Fibrolamellar Carcinoma of Liver: A Primary Malignant Oncocytic Carcinoid?

Immunohistochemical and ultrastructural findings in two cases of fibrolamellar carcinoma of the liver and two cases of hepatocellular carcinoma of the common histologic type are described. Ultrastructural examination of both cases of fibrolamellar carcinoma revealed the presence of neurosecretory (NS) granules which were sparse in some cells and abundant in others. Many of the tumor cells had a distinct oncocytic appearance with abundant mitochondria. A portion of the glutaraldehyde-fixed neoplasm was processed for the uranaffin reaction (an ultrastructural cytochemical stain specific for the NS granules of neuroendocrine tissue). Abundant uranaffin-positive granules were found in the neoplastic cells of both cases of fibrolamellar carcinoma, whereas no uranaffin-positive granules were found in hepatocellular carcinoma of the common histologic type. There was no statistical difference in the mean diameter of the uranaffin-positive granules measured from both cases. Immunohistochemistry revealed the presence of neuron-specific enolase (NSE) and serotonin in one of the two cases of fibrolamellar carcinoma and no NSE staining in two cases of hepatocellular carcinoma of the common histologic type. These findings suggest that some liver tumors presenting histologically as fibrolamellar carcinoma may be neuroendocrine in nature.

Virtual slide telepathology for an academic teaching hospital surgical pathology quality assurance program.

Virtual slide telepathology is an important potential tool for providing re-review of surgical pathology cases as part of a quality assurance program. The University of Arizona pathology faculty has implemented a quality assurance program between 2 university hospitals located 6 miles apart. The flagship hospital, University Medical Center (UMC), in Tucson, AZ, handles approximately 20 000 surgical pathology specimens per year. University Physicians Healthcare Hospital (UPHH) at Kino Campus has one tenth the volume of surgical pathology cases. Whereas UMC is staffed by 10 surgical pathologists, UPHH is staffed daily by a single part-time pathologist on a rotating basis. To provide same-day quality assurance re-reviews of cases, a DMetrix DX-40 ultrarapid virtual slide scanner (DMetrix, Inc, Tucson, AZ) was installed at the UPHH in 2005. Since then, glass slides of new cases of cancer and other difficult cases have been scanned the same day the slides are produced by the UPHH histology laboratory. The pathologist at UPHH generates a provisional written report based on light microscopic examination of the glass slides. At 2:00 pm each day, completed cases from UPHH are re-reviewed by staff pathologists, pathology residents, and medical students at the UMC using the DMetrix Iris virtual slide viewer. The virtual slides are viewed on a 50-in plasma monitor. Results are communicated with the UPHH laboratory by fax. We have analyzed the results of the first 329 consecutive quality assurance cases. There was complete concordance with the original UPHH diagnosis in 302 (91.8%) cases. There were 5 (1.5%) major discrepancies, which would have resulted in different therapy and/or management, and 10 (3.0%) minor discrepancies. In 6 cases (1.8%), the diagnosis was deferred for examination of the glass slides by the reviewing pathologists at UMC, and the diagnosis of another 6 (1.8%) cases were deferred pending additional testing, usually immunohistochemistry. Thus, the quality assurance program found a small number of significant diagnostic discrepancies. We also found that implementation of a virtual slide telepathology quality assurance service improved the job satisfaction of academic subspecialty pathologists assigned to cover on-site surgical pathology services at a small, affiliated university hospital on a rotating part-time basis. These findings should be applicable to some community hospital group practices as well.