Once-Weekly Insulin Icodec With Dosing Guide App Versus Once-Daily Basal Insulin Analogues in Insulin-Naive Type 2 Diabetes (ONWARDS 5) : A Randomized Trial

BACKGROUND

Inadequate dose titration and poor adherence to basal insulin can lead to suboptimal glycemic control in persons with type 2 diabetes (T2D). Once-weekly insulin icodec (icodec) is a basal insulin analogue that is in development and is aimed at reducing treatment burden.

OBJECTIVE

To compare the effectiveness and safety of icodec titrated with a dosing guide app (icodec with app) versus once-daily basal insulin analogues (OD analogues) dosed per standard practice.

DESIGN

52-week, randomized, open-label, parallel-group, phase 3a trial with real-world elements. (ClinicalTrials.gov: NCT04760626).

SETTING

176 sites in 7 countries.

PARTICIPANTS

1085 insulin-naive adults with T2D.

INTERVENTION

Icodec with app or OD analogue (insulin degludec, insulin glargine U100, or insulin glargine U300).

MEASUREMENTS

The primary outcome was change in glycated hemoglobin (HbA1c) level from baseline to week 52. Secondary outcomes included patient-reported outcomes (Treatment Related Impact Measure for Diabetes [TRIM-D] compliance domain score and change in Diabetes Treatment Satisfaction Questionnaire [DTSQ] total treatment satisfaction score).

RESULTS

The estimated mean change in HbA1c level from baseline to week 52 was greater with icodec with app than with OD analogues, with noninferiority (P < 0.001) and superiority (P = 0.009) confirmed in prespecified hierarchical testing (estimated treatment difference [ETD], -0.38 percentage points [95% CI, -0.66 to -0.09 percentage points]). At week 52, patient-reported outcomes were more favorable with icodec with app than with OD analogues (ETDs, 3.04 [CI, 1.28 to 4.81] for TRIM-D and 0.78 [CI, 0.10 to 1.47] for DTSQ). Rates of clinically significant or severe hypoglycemia were low and similar with both treatments.

LIMITATION

Inability to differentiate the effects of icodec and the dosing guide app.

CONCLUSION

Compared with OD analogues, icodec with app showed superior HbA1c reduction and improved treatment satisfaction and compliance with similarly low hypoglycemia rates.

PRIMARY FUNDING SOURCE

Novo Nordisk A/S.

Weekly Icodec versus Daily Glargine U100 in Type 2 Diabetes without Previous Insulin

BACKGROUND

Insulin icodec is an investigational once-weekly basal insulin analogue for diabetes management.

METHODS

We conducted a 78-week randomized, open-label, treat-to-target phase 3a trial (including a 52-week main phase and a 26-week extension phase, plus a 5-week follow-up period) involving adults with type 2 diabetes (glycated hemoglobin level, 7 to 11%) who had not previously received insulin. Participants were randomly assigned in a 1:1 ratio to receive once-weekly insulin icodec or once-daily insulin glargine U100. The primary end point was the change in the glycated hemoglobin level from baseline to week 52; the confirmatory secondary end point was the percentage of time spent in the glycemic range of 70 to 180 mg per deciliter (3.9 to 10.0 mmol per liter) in weeks 48 to 52. Hypoglycemic episodes (from baseline to weeks 52 and 83) were recorded.

RESULTS

Each group included 492 participants. Baseline characteristics were similar in the two groups. The mean reduction in the glycated hemoglobin level at 52 weeks was greater with icodec than with glargine U100 (from 8.50% to 6.93% with icodec [mean change, -1.55 percentage points] and from 8.44% to 7.12% with glargine U100 [mean change, -1.35 percentage points]); the estimated between-group difference (-0.19 percentage points; 95% confidence interval [CI], -0.36 to -0.03) confirmed the noninferiority (P<0.001) and superiority (P = 0.02) of icodec. The percentage of time spent in the glycemic range of 70 to 180 mg per deciliter was significantly higher with icodec than with glargine U100 (71.9% vs. 66.9%; estimated between-group difference, 4.27 percentage points [95% CI, 1.92 to 6.62]; P<0.001), which confirmed superiority. Rates of combined clinically significant or severe hypoglycemia were 0.30 events per person-year of exposure with icodec and 0.16 events per person-year of exposure with glargine U100 at week 52 (estimated rate ratio, 1.64; 95% CI, 0.98 to 2.75) and 0.30 and 0.16 events per person-year of exposure, respectively, at week 83 (estimated rate ratio, 1.63; 95% CI, 1.02 to 2.61). No new safety signals were identified, and incidences of adverse events were similar in the two groups.

CONCLUSIONS

Glycemic control was significantly better with once-weekly insulin icodec than with once-daily insulin glargine U100. (Funded by Novo Nordisk; ONWARDS 1 ClinicalTrials.gov number, NCT04460885.).

Rationale and design of the phase 3a development programme (ONWARDS 1-6 trials) investigating once-weekly insulin icodec in diabetes

AIM

To describe the phase 3a ONWARDS clinical development programme investigating insulin icodec (icodec), a once-weekly basal insulin, including the design and rationale for each of the ONWARDS 1-6 trials.

MATERIALS AND METHODS

Six randomized controlled trials have been initiated in adults with type 2 diabetes (T2D) (insulin-naive: ONWARDS 1, 3 and 5; previously insulin-treated: ONWARDS 2 and 4) and type 1 diabetes (T1D) (ONWARDS 6). Each trial will investigate icodec use in a unique clinical scenario, with consideration of long-term safety and varied comparator treatments (insulin glargine U100 or U300 or insulin degludec). ONWARDS 5 will incorporate real-world elements and a digital dose titration solution to guide icodec dosing. The primary objective for each of the trials is to compare the change in HbA1c from baseline to week 26 or week 52 between icodec and comparator arms. Secondary objectives include investigating other glycaemic control and safety parameters, such as fasting glucose, time in glycaemic range and hypoglycaemia. Patient-reported outcomes will assess treatment satisfaction.

CONCLUSIONS

The ONWARDS 1-6 trials will evaluate the efficacy and safety of once-weekly icodec compared with currently available daily basal insulin analogues in T2D and T1D. These trials will generate comprehensive evidence of icodec use in diverse populations across the spectrum of diabetes progression and treatment experience.

306 In the COVID Aftermath, Using an Innovative Collaborative Approach to Improve Wait Times for Skin Cancer Patients

COVID-19 led to drastic reductions in non-urgent medical visits and cancer care. Surgical patient backlogs mean new strategies are required to decrease wait times and administrative costs whilst improving patient outcomes. We review the impact of combined speciality Plastic Surgery and Dermatology 2 week-wait (2ww) clinics on wait times and hospital attendances and associated cost implications when compared to the single speciality clinics.

Retrospective analysis comparing Plastic surgery (PS) and Dermatology (DM) 2ww clinics against combined Dermatology and Plastic surgery (DP) clinics across the same 3-month period in 2018 and 2019 at a single UK tertiary centre.

283 patients reviewed across the same 3-month period in 2018 and 2019 (PS n = 53, DM n = 158, PD n = 72). PD reviewed most patients per clinic (Averages: PD n = 18.0, PS n = 8.8, DM n = 12.1). Hospital attendance decreased from 1.84 to 1.51 visits. 42.9% of excisional biopsies were performed on the same day as initial assessment compared to 18.0% in PS/DM clinics. Referral to surgery time decreased from 67.7days to 50.4 days, and tertiary assessment to surgery from 49.5days to 36.9days. PD attracted tariffs of up to £29.78 more per patient.

Combined clinics see more patients and attract higher tariffs per patient, whilst reducing outpatient attendances and wait times to surgery. This has significant cost-saving implications whilst optimising cancer care.

Hemoglobin glycation index, calculated from a single fasting glucose value, as a prediction tool for severe hypoglycemia and major adverse cardiovascular events in DEVOTE

INTRODUCTION

Hemoglobin glycation index (HGI) is the difference between observed and predicted glycated hemoglobin A1c (HbA_1c), derived from mean or fasting plasma glucose (FPG). In this secondary, exploratory analysis of data from DEVOTE, we examined: whether insulin initiation/titration affected the HGI; the relationship between baseline HGI tertile and cardiovascular and hypoglycemia risk; and the relative strengths of HGI and HbA_1c in predicting these risks.

RESEARCH DESIGN AND METHODS

In DEVOTE, a randomized, double-blind, cardiovascular outcomes trial, people with type 2 diabetes received once per day insulin degludec or insulin glargine 100 units/mL. The primary outcome was time to first occurrence of a major adverse cardiovascular event (MACE), comprising cardiovascular death, myocardial infarction or stroke; severe hypoglycemia was a secondary outcome. In these analyses, predicted HbA_1c was calculated using a linear regression equation based on DEVOTE data (HbA_1c=0.01313 FPG (mg/dL) (single value)+6.17514), and the population data were grouped into HGI tertiles based on the calculated HGI values. The distributions of time to first event were compared using Kaplan-Meier curves; HRs and 95% CIs were determined by Cox regression models comparing risk of MACE and severe hypoglycemia between tertiles.

RESULTS

Changes in HGI were observed at 12 months after insulin initiation and stabilized by 24 months for the whole cohort and insulin-naive patients. There were significant differences in MACE risk between baseline HGI tertiles; participants with high HGI were at highest risk (low vs high, HR: 0.73 (0.61 to 0.87)_{95% CI}; moderate vs high, HR: 0.67 (0.56 to 0.81)_{95% CI}; p<0.0001). No significant differences between HGI tertiles were observed in the risk of severe hypoglycemia (p=0.0911). With HbA_1c included within the model, HGI no longer significantly predicted MACE.

CONCLUSIONS

High HGI was associated with a higher risk of MACE; this finding is of uncertain significance given the association of HGI with insulin initiation and HbA_1c.

TRIAL REGISTRATION NUMBER

NCT01959529.

975 On Call on Friday 13th: Unlucky for Some?

Introduction

Despite the practice of evidence-based medicine, superstitions remain common amongst healthcare workers around the world. Friday 13th is a day that can cause anxiety amongst many surgeons on-call. Our aim was to determine whether there is a significant difference between working an on-call as a surgeon on Friday 13th compared to the preceding Friday at a large teaching hospital.

Method

We conducted a retrospective, longitudinal cohort study that analysed admissions and operative data for all emergency general surgical and urology patients at a large teaching hospital over a five-year period. The main outcome measures assessed included the number of emergency surgical admissions, emergency general surgical operations and emergency urological operations.

Results

There was no statistically significant difference between the number of admissions (412 vs 405, p=0.835), number of general surgical operations (63 vs 49, p=0.069), and number of urological operations (2 vs 4, p=0.449) on Friday 13th compared to Friday 6th.

Conclusions

Friday 13th will inevitably be unlucky for some, but this study shows that being on-call on Friday 13th is just as unlucky as being on-call any other Friday.

84 Optimising The Assessment and Management of Acute Renal Colic in Secondary Care

Aim

The latest guidance in acute renal colic states that patients should have serum calcium and urate (stone bloods) measured during inpatient admission. The guidance also states that follow-up imaging should be in the form of computed tomography (CT)-, ultrasound (USS)-, or X-ray- kidney, ureters and bladder (KUB). X-ray intravenous urogram (IVU) is now considered obsolete as it can result in over-exposing patients to radiation. Aims of this 2-cycle QIP were twofold;

Method

Data was extracted from electronic patient records on whether or not they had stone bloods measured during admission and also what follow-up imaging was requested. In the first cycle baseline data was extracted. A stone proforma was then created, incorporating the latest guidelines. In the second cycle the impact of the stone proforma was assessed.

Results

The study included 119 patients. After introducing the stone proforma we were successful in improving the rate of stone bloods being measured, increasing from 13% to 53%. We were also successful in reducing the rate of performing X-ray IVU, decreasing from 25% to 14% of patients.

Conclusions

This QIP demonstrates that management of acute renal colic can be optimised using a stone proforma and move current practice towards best practice. This is supported by the ‘Getting it Right First Time’ (GIRFT) Urology report 2018. The third cycle is currently underway, and we hope to see further improved outcomes.

985 Improving the Accessibility and Quality of Junior Doctor's Rotas During the Covid19 Pandemic

Introduction

Rotas are an important part of a Junior Doctors working life. Having an up to date and accessible rota is important in enhancing Junior Doctor’s working lives in addition to being vital for work force planning and patient safety. During the Covid19 pandemic, rotas have changed several times making it difficult to track changes. Prior to our project, Junior Doctors found it neither difficult nor easy to access rotas at work (2.84 out of 5), found it fairly difficult to access rotas at home (2.38 out of 5) and the rotas they had access to were only average in being up to date (2.69 out of 5). Our project looked to improve this.

Method

Data was collected by surveys sent to Junior Doctors in the surgical department. PDSA Cycle 1 involved implementing surgical rotas on Microsoft Teams. PDSA Cycle 2 involved having other speciality rotas on Microsoft Teams. Our aims were to improve accessibility of rotas both at home and in the workplace whilst improving how up to date the available rota is.

Results

After the surgical rotas were on Microsoft Teams, rotas were easy to access at work (4.64 out of 5), fairly easy to access at home (4.24 out of 5) and were mostly up to date (4.41 out of 5). This has led to an improved satisfaction amongst Junior Doctors.

Conclusions

Currently the surgical department in Derby is using our solution for rotas. Medical staffing is in the midst of implementing this in the Medical speciality.

634 Case Report: Large Perforating Ileal Conduit Stone as A Rare Cause of Abdominal Wall Abscess

Introduction

Ileal conduits are common following cystectomy for benign or malignant disease of the bladder. They are associated with late complications such as parastomal hernias, strictures, infections and rarely conduit stone formation. We present a previously unreported case of a significant abdominal wall abscess secondary to a very large perforating conduit stone.

Case Report

A 59-year-old female with an established ileal conduit due to multiple sclerosis presented acutely with abdominal pain, peristomal mass and fever. A CT showed a large (40mm) calcification with a fluid collection adjacent to the conduit in the subcutaneous tissues. Emergency incision and drainage of the abscess revealed a large abscess cavity containing a stone. Conduitoscopy demonstrated a narrow stoma and a perforation between the abscess cavity and the lumen of the conduit suggesting extrusion of the stone through an eroded area in the wall of the conduit. A Foley catheter was inserted to bypass the perforation. The patient recovered well after the procedure with the addition of antibiotics. Subsequent conduitoscopy showed closure of the perforation with these measures.

Conclusions

Conduit stones are rare but have the potential to perforate the urinary conduit. We believe that the subcutaneous location of the perforation allowed it to go unnoticed and the stone to achieve a significant size before acting as a nidus for infection. A more proximal perforation would likely result in an intraperitoneal urine leak and earlier presentation with an acute abdomen.

991 Managing Recurrent Bleeding from Varicose Veins of The Scrotum: A Case Report

Introduction

Spontaneous recurrent bleeding scrotal varicosity is a rare clinical presentation. The management is undefined and is usually anecdotal from previous case reports. The anatomy and pathophysiology of these presentations are usually complex hence resulting in atypical and challenging management options. To highlight this, we present a case of a patient with recurrent scrotal bleeding secondary to scrotal varicosities.

Care report

A 39-year-old gentleman with heart failure, 4 previous episodes of transient ischemic attacks and atrial fibrillation who was anticoagulated, presented with recurrent left sided scrotal bleeding from dilated superficial scrotal veins. In total, he had 11 presentations over 4 years requiring blood transfusion on 4 occasions. On one occasion the patient required 7 units of packed red blood cells transfused. He had a background of heart failure with hepatic congestion and ascites which failed medical management. Compression, adrenaline and tranexamic acid-soaked gauze, as well as over-sewing feeder vessels offered only short-term relief. His heart failure was difficult to optimise and stopping anticoagulation was not possible, even for a short period of time, due to the high risk of stroke in this patient. Venography revealed a prominent left testicular vein that extensively fed the scrotal veins with bilateral varicoceles. After discussion with the Vascular team, percutaneous coil embolization of the left testicular vein was performed with good results. He has had no significant scrotal bleeding since.

Conclusions

Managing bleeding scrotal varicose veins can be challenging. A multidisciplinary approach may be the most appropriate in managing these patients.

Duration of type 2 diabetes does not appear to moderate hypoglycaemia rate with insulin degludec versus insulin glargine U100

In the DEVOTE and SWITCH 2 trials, insulin degludec 100 units/mL (degludec) was superior to insulin glargine 100 units/mL (glargine U100) with respect to the rates of severe (DEVOTE; across trial) and overall symptomatic (SWITCH 2; during the maintenance period of the trial) hypoglycaemia in individuals with type 2 diabetes. In this post hoc analysis, data from 7635 individuals from DEVOTE and 720 individuals from SWITCH 2 were analysed by subgroups of diabetes duration at baseline (<10, ≥10-<15, ≥15-<20 and ≥20 years) using prespecified models from both trials. There was a trend towards lower rates of hypoglycaemia with degludec versus glargine U100 across all diabetes duration subgroups in both trials, with the difference being statistically significant in some subgroups in DEVOTE and SWITCH 2. Overall, however, no significant interaction was observed between diabetes duration and treatment (DEVOTE interaction, P = .496; SWITCH 2 interaction, P = .144). Therefore, in this post hoc analysis of DEVOTE and SWITCH 2, diabetes duration did not appear to affect the reduction in rates of hypoglycaemia observed with degludec compared with glargine U100.

Switching to Once-Weekly Insulin Icodec Versus Once-Daily Insulin Glargine U100 in Type 2 Diabetes Inadequately Controlled on Daily Basal Insulin: A Phase 2 Randomized Controlled Trial

OBJECTIVE

Insulin icodec (icodec) is a novel once-weekly basal insulin analog. This trial investigated two approaches for switching to icodec versus once-daily insulin glargine 100 units/mL (IGlar U100) in people with type 2 diabetes receiving daily basal insulin and one or more oral glucose-lowering medications.

RESEARCH DESIGN AND METHODS

This multicenter, open-label, treat-to-target phase 2 trial randomized (1:1:1) eligible basal insulin-treated (total daily dose 10-50 units) people with type 2 diabetes (HbA_1c 7.0-10.0% [53.0-85.8 mmol/mol]) to icodec with an initial 100% loading dose (in which only the first dose was doubled [icodec LD]), icodec with no loading dose (icodec NLD), or IGlar U100 for 16 weeks. Primary end point was percent time in range (TIR; 3.9-10.0 mmol/L [70-180 mg/dL]) during weeks 15 and 16, measured using continuous glucose monitoring. Key secondary end points included HbA_1c, adverse events (AEs), and hypoglycemia.

RESULTS

Estimated mean TIR during weeks 15 and 16 was 72.9% (icodec LD; n = 54), 66.0% (icodec NLD; n = 50), and 65.0% (IGlar U100; n = 50), with a statistically significant difference favoring icodec LD versus IGlar U100 (7.9%-points [95% CI 1.8-13.9]). Mean HbA_1c reduced from 7.9% (62.8 mmol/mol) at baseline to 7.1% (54.4 mmol/mol icodec LD) and 7.4% (57.6 mmol/mol icodec NLD and IGlar U100); incidences and rates of AEs and hypoglycemic episodes were comparable.

CONCLUSIONS

Switching from daily basal insulin to once-weekly icodec was well tolerated and provided effective glycemic control. Loading dose use when switching to once-weekly icodec significantly increased percent TIR during weeks 15 and 16 versus once-daily IGlar U100, without increasing hypoglycemia risk.

261 Using Technology to Improve Inpatient Surgical Lists

Introduction

Every day in our surgical department; prior to our quality improvement project, Junior Doctors spent on average 3.26 clinical hours maintaining 5 surgical inpatient lists of different specialities with accessibility of lists rated as “neutral” based on a 5-point scale from difficult to easy. Our hospital previously had lists stored locally on designated computers causing recurrent difficulties in accessing and editing these lists.

Method

We used surveys sent to clinicians to collect data.

Cycle 1: Surgical Assessment Units list on Microsoft Teams

Cycle 2: Addition of surgical specialities and wards lists onto Microsoft Teams.

Cycle 3 (current): expand the use of Microsoft Teams to other specialities.

Results

Utilising technology led to a 25% reduction in time spent on maintaining inpatient lists, to 2.46 hours a day, and an improvement in the accessibility of lists to “easy”. Across a year, this saves over 220 hours clinician hours which can be used towards patient care and training. Furthermore, use of Microsoft Teams has improved communication and patient care, in the form of virtual regional Multi-Disciplinary Team meetings and research projects.

Conclusions

Microsoft Teams is currently free to all NHS organisations in England so there is potential for these efficiency savings to be replicated nationwide.

Technical developments for cerebral thermal treatment: water-cooled diffusing laser fibre tips and temperature-sensitive MRI using intersecting image planes

The aim was to determine if water-cooled diffusing tips could produce larger and safer (better controlled) thermal lesions than non-cooled diffusing tips at 980 nm. Thermal lesions were induced in beef myocardium in vitro with and without water cooling using a 980 nm diode laser at various power levels. Seven intracerebral treatments were performed in six canines using water-cooled diffusing tips with four animals having intracerebral transmissible venereal tumours grown from inoculate. Magnetic resonance thermal imaging (MRTI)-based feedback software using a fast, radio frequency-spoiled gradient echo acquisition with two intersecting image planes was used for on-line monitoring and control of treatment and for the evaluation of in vivo laser lesion production. In cases where two-plane MRTI was employed, the maximum calculated temperature was compared in each plane. Using water-cooled tips and 400 micro m core diameter laser diffusing fibres in in vitro beef myocardium, power of up to 9.5 W was applied for 8 min without tip failure. Without cooling, tip failure occurred in under 4 min at 6 W, in under 2 min at 7 W and instantaneously at 8 W. Additionally, char accompanied lesions made with uncooled tips while cooled application resulted in only minimal char at only the highest thermal dose. Achieved lesion cross-sectional diameters in in vitro samples were up to 26.5 x 23.3 mm when water cooling was used. In canine brain and transmissible venereal tumours, up to 18.1 x 21.4 mm lesions were achieved. It is concluded that water cooling allows safe application of higher power to small core diameter diffusing tip fibres, which results in larger thermal lesions than can be achieved without cooling. Two-plane MRTI enhances on-line monitoring and feedback of thermal treatment.

Cooled-tip diode laser catheter for improved catheter ablation of ventricular tachycardia

Catheter ablation for the treatment of arrhythmias has evolved dramatically over the past two decades. Researchers have investigated alternative energy sources and catheter constructs to improve the efficacy and safety of catheter ablation. This study tested the hypothesis that a new prototype cooled-tip laser catheter used with a low-power diode laser would improve catheter ablation of ventricular tachycardias. Four mongrel dogs underwent a median sternotomy. The cooled-tip laser catheter was advanced into the left ventricle via the left carotid artery and positioned adjacent to the endocardium. Laser powers of 3 and 4 W were delivered at four exposure times to select areas of the endocardium. During application of laser energy, room-temperature saline was circulated through the catheter. At necropsy the hearts were examined and fixed in formalin for histologic examination. Gross examination of the endocardial surfaces showed no indication of crater or thrombus formation. Cross-section of the lesions revealed sharply demarcated, circular-shaped areas of coagulative necrosis extending into the mid-myocardium. Areas of coagulative necrosis were identified within the myocardium extending into the mid-myocardium and occasionally the subepicardium. A sharp line of demarcation was observed between the lesions and the surrounding normal myocardium. The results of this study showed that we could use surface cooling during slow laser heating to create large subsurface lesions with characteristics appropriate for treatment of ventricular tachycardia and little to no surface damage. We believe our catheter system addresses many of the previous issues with laser-based approaches.

Legionella micdadei lung abscess in a patient with HIV-associated nephropathy

A patient with end-stage renal disease due to human immunodeficiency-associated nephropathy developed fever, cough and chest pain over a week's duration. He was diagnosed with lung abscess and started on antibiotic coverage. He underwent bronchoscopy because of progression of his illness and persistent fever and bronchoalveolar lavage culture isolated Legionella micdadei. In spite of appropriate antibiotic therapy, the patient remained febrile for 10 days, necessitating chest tube drainage. After a 6-week course of antibiotics and drainage, the patient made an uneventful recovery. Infections due to L. micdadei may be hard to diagnose because of difficulties in isolating this bacteria.

Ventricular arrhythmias following thermal damage of epicardial tissue: possible causes and clinical implications

Epicardial heating may be used for ventricular tachycardia (VT) ablation and transmyocardial revascularization. However, the potential risks of thermal epicardial injury, including arrhythmia, have not been fully explored. This study relates the pathologic and arrhythmic sequellae of epicardial heating when applied with a diode laser at varying doses. Acute pathology and dosimetry were determined in a group of normal dogs using 2-3 W over 30-90 seconds. Another group received a similar dose range before undergoing 24-hour monitoring, and electrophysiological testing was done at 4 weeks. In this group, four dogs each received 12 lesions (90-180 J) according to a randomized block design. Another dog received nine lower dose lesions (30-120 J). Acute lesions measured 2.5-8.0-mm wide by 4-8.5-mm deep. Charring and vaporization were common when 3 W were applied over 45 seconds. Within 24 hours, VT with features of abnormal automaticity occurred in all dogs receiving this dose. The dog in whom lower doses induced coagulation only had no VT. Four weeks later, electrophysiological study induced no VT. At this time fibrosis and granulation tissue were organizing the contraction band necrosis seen acutely, and some lesion borders were becoming calcified. No major vessels had been damaged. Abnormal automaticity and VT may occur if thermal damage of the epicardium exceeds coagulation. This could be related to tissue injury caused by sudden water vaporization, and may have clinical relevance given the growing indications for myocardial heating.

Slow intramural heating with diffused laser light: A unique method for deep myocardial coagulation

BACKGROUND

Catheter ablation of postinfarction ventricular tachycardia (VT) may be limited by insufficient myocardial coagulation or excessive endocardial or epicardial damage. We propose that volumetric heating restricted to intramural sites may improve the outcome and safety of this procedure, especially if delivered at rates that enhance heat conduction and forestall adverse tissue changes.

METHODS AND RESULTS

A novel optical fiber with a diffusing tip for direct intramural, volumetric laser heating was tested via thoracotomy and percutaneously in normal dogs. Low-power (2.0- to 4.5-W) diode laser light (805 nm) diffused within tissue induced large lesions but no visible surface damage, mural thrombi, or transmural perforation. Mean lesion depth approximated tip length (10 mm). Mean lesion widths in the thoracotomy and percutaneous groups were 5.8+/-0.5 to 9.1+/-0.84 mm and 5.2+/-0.85 to 7.9+/-1.1 mm, respectively, depending on the light dose. Mean volumes in the percutaneous group were 1006+/-245 to 2471+/-934 mm. ST-segment depression, appearing in unfiltered bipolar electrograms recorded from the guiding catheter, was specific for lesion induction. All dogs survived the protocol, which included a 1-hour observation period. In cross section, lesions were elliptical to spherical and characterized by extensive contraction-band necrosis abruptly bordering viable tissue. No platelets or fibrin adhered to the endocardium.

CONCLUSIONS

Slow, volumetric, and direct intramyocardial heating induces large, deep lesions without hazardous tissue damage. Such heating might cure postinfarction VT more successfully and safely than present techniques. Further testing and development of this method seem warranted.

Heat shock improves recovery and provides protection against global ischemia after hypothermic storage

BACKGROUND

Improved methods of donor heart preparation before preservation could allow for prolonged storage and permit remote procurement of these organs. Previous studies have shown that overexpression of heat-shock protein 72 provides protection against ischemic cardiac damage. We sought to determine whether rats subjected to heat stress with only 6-hour recovery could acquire protection to a subsequent heart storage for 12 hours at 4 degrees C.

METHODS

Three groups of animals (n = 10 each) were studied: control, sham-treated, and heat-shocked rats (whole-body hyperthermia 42 degrees C for 15 minutes). After 12-hour cold ischemia hearts were reperfused on a Langendorff column. To confirm any differences in functional recovery, hearts were then subjected to an additional 15-minute period of warm global ischemia after which function and lactate dehydrogenase enzyme leakage were measured.

RESULTS

Heat-shocked animals showed marked improvements compared with controls in left ventricular developed pressure (63+/-4 mm Hg versus 44+/-4 mm Hg, p<0.05) heart rate x developed pressure (13,883+/-1,174 beats per minute x mm Hg versus 8,492+/-1,564 beats per minute x mm Hg, p<0.05), rate of ventricular pressure increase (1,912+/-112 mm Hg/second versus 1,215+/-162 mm Hg/second, p<0.005), rate of ventricular pressure decrease (1,258+/-89 mm Hg/second versus 774+/-106 mm Hg/second, p<0.005). Diastolic compliance and lactate dehydrogenase release were improved in heatshocked animals compared with controls and sham-treated animals. Differences between heat-shocked animals and control or sham-treated animals were further increased after the additional 15-minute period of warm ischemia. Western blot experiments confirmed increased heat-shock protein 72 levels in heat-shocked animals (>threefold) compared with sham-treated animals and controls.

CONCLUSIONS

Heat shock 6 hours before heart removal resulted in marked expression of heat-shock protein 72 and protected isolated rat hearts by increased functional recovery and decreased cellular necrosis after 12-hour cold ischemia in a protocol mimicking that of heart preservation for transplantation. Protection was further confirmed after an additional 15-minute period of warm ischemia.

Cardioprotection by local heating: improved myocardial salvage after ischemia and reperfusion

BACKGROUND

Previous studies have shown that expression of the inducible 70-kD heat-shock protein (HSP72) by whole-body hyperthermia is associated with protection against ischemia-reperfusion injury. To develop techniques for regional elevation of heat-shock proteins that prevent extracardiac sequelae during whole-body hyperthermia, we sought to determine if local heating of the heart in vivo provides protection against ischemia-reperfusion injury in the rat.

METHODS

A thermal probe was used to locally heat rat hearts at two adjacent sites on the epicardial surface of the left ventricle. Rats were subjected to either 30 minutes of sham surgery (control; n = 10) or two local applications of the probe at 42.5 degrees to 43.5 degrees C for 15 minutes each (n = 9). After 4 hours, rats were subjected to 30 minutes of regional ischemia followed by 120 minutes of reperfusion. Hearts were removed and area at risk and infarct area were determined.

RESULTS

Localized heat stress resulted in a significant limitation of infarct size in heat-treated animals versus controls (mean +/- standard error of the mean infarct area/area at risk = 4.3% +/- 0.85 versus 19.2% +/- 3.4%; p < 0.005). Western blot experiments confirmed elevated HSP72 expression in left (heated) and right (nonheated) ventricular samples from treated animals (n = 6; left ventricular = 5.5-fold; right ventricular = 3.7-fold) compared with sham-operated controls. Controls treated with the probe at 37 degrees C (n = 4) showed no increases in HSP72.

CONCLUSIONS

Local heating of the heart is associated with elevated levels of HSP72 and improved myocardial salvage. The increase in expression of HSP72 is not limited to the heated region, but extends into nonheated regions of the heart as well. This may lead to the development of new techniques that improve methods of myocardial revascularization and heart transplantation procedures.

Laboratory diagnosis of Japanese encephalitis using monoclonal antibodies and correlation of findings with the outcome

Detection of virus, viral antigen, and class-specific antibody was carried out in cerebrospinal fluid (CSF) and sera of 27 children with Japanese encephalitis. The diagnosis could be confirmed in 78.57% of cases (22/27) by demonstration of virus-specific IgM in CSF (15/22), viral antigen in CSF (5/22), or by virus isolation (2/22). Absence of virus specific IgM in CSF was associated with a fatal outcome (P = 0.05).