Anatomical variations in coronary venous drainage: challenges and solutions in delivering cardiac resynchronisation therapy

Funding Acknowledgements

Type of funding sources: None.

Background

Cardiac resynchronisation therapy (CRT) is the cornerstone of heart failure management. Delivery of a left ventricular lead can occur in a small proportion of patients undermining the benefits of this treatment. Abnormal coronary venous anatomy is a contributing factor to this failure. Although epicardial lead placement is available, this patient cohort requiring CRT is subject to higher peri-operative morbidity and mortality than the general population; a transvenous approach is preferable.

Purpose

To investigate the abnormalities of the coronary venous system in candidates for cardiac resynchronization therapy (CRT) and describe methods for circumventing the resulting difficulties.

Methods

From 4 implanting institutes, data of all CRT implants between October 2008-October 2020 were screened for abnormal cardiac venous anatomy, defined as an anatomical variation not conforming to the accepted ‘normal’ anatomy. Patient demographics, procedural detail and subsequent left ventricle (LV) lead pacing indices were collected.

Results

From a total of 3548 CRT implants, 15 (0.42%) patients (80% male) of 72.2±10.6 years in age with a LV ejection fraction of 34±10.3% were identified to have had an abnormal cardiac venous anatomy over the study period. There were 13 cases of persistent left side superior vena cava (pLSVC), 5 of which had coronary sinus ostium atresia (CSOA) including 2 with an ‘unroofed’ coronary sinus (CS); 1 patient had a unique anomalous origin of the CS and 1 patient had an isolated CSOA. In total 14 patients (60% repeat attempt) had successful percutaneous implant under general anaesthesia (46.7%) via the cephalic vein (59.1%), using the femoral approach (53.3%) for levophase venography and/or pull-through, including 1 case of endocardial LV implant. Pacing follow-up over 37.64±37.6 months demonstrated LV lead threshold between 0.62-2.9 volts (pulsewidth 0.4-1.5 milliseconds) in all cases; 5 patients died within 2.92±1.6 years of successful implant.

Conclusion

CRT devices can be implanted percutaneously even in the presence of substantial abnormalities of coronary venous anatomy. Alternative routes of venous access may be required.

Transvenous lead extraction: the Tandem approach

Funding Acknowledgements

Type of funding sources: None.

Background

Transvenous lead extraction (TLE) has become an important strategy in the management of patients with cardiac implantable electronic devices (CIEDs). A rising population of patients with CIEDs coupled with an expanding indication for TLE, has fuelled demand. There are notable procedural risks however development of techniques and tools have contributed to an improvement in the safety and efficacy of TLE. The mechanical rotational dissecting sheath is safe and efficacious whilst the Needle’s Eye Snare (NES) is an additional ‘bail-out’ strategy contributing to procedural success.

Purpose

We sought to evaluate the outcomes of TLE performed from the superior access in conjunction with counter-traction provided by snaring of the targeted lead via the femoral access.

Method

The ‘Tandem’ procedure consisted of the rotational powered sheath performing dissection of the adhesions encapsulating the leads (at the superior access), in ‘Tandem’ with the Needle’s Eye Snare providing countertraction via the femoral vein. In brief: after deployment of the locking stylet in the lead lumen, the NES was used to grasp the lead in the right atrium and hold it tort while a rotational sheath was used to dissect through the veins. Once the sheath reached the right atrium, the lead was released from the snare and the sheath was used to continue dissection toward the lead tip. Data for all consecutive ‘Tandem’ procedures performed between 1/1/2021 – 1/1/2022 in our high-volume TLE institute were collected and evaluated for safety and efficacy.

Results

Forty patients aged 69.2±16.3 (70% male), underwent TLE of 75 leads (45 right ventricle, 25, right atrium, 5 left ventricle) with dwell time of 150.1±80.3 months for a non-infectious indication (65%). Of the 40 cases, 27 were hypertensives, 14 had ischaemic heart disease whilst 5 suffered diabetes with a left ventricle ejection fraction of 46.8±10.2%; 12 (30%) were pacing dependent. Procedures were performed by cardiologists in the cardiac catheterisation suite under general anaesthesia (95%) using a locking stylet (100%) with an Evolution RL (11-french 58.7%); a NES 13 millimetres curve (88%) was used to successfully snare 91% of the targeted leads. Complete procedural success was achieved in 92% of leads with 98.7% clinical success. Minor complications occurred in 2 cases (pneumothorax, pocket haematoma requiring intervention), in the absence of any major complications or peri-procedural mortality; there was no 30-day mortality.

Conclusion

The ‘Tandem’ procedure provides an additional strategy to improve the safety and efficacy of TLE, especially in leads of a long dwell time.

Oesophageal protection during AF ablation: real world registry data and mechanisms behind the therapeutic effect of tissue cooling

Funding Acknowledgements

Type of funding sources: None.

Background

Oesophageal protection using a dedicated device to provide controlled active thermal protection of the oesophagus during atrial fibrillation ablation has been shown to be effective at reducing endoscopically detected oesophageal lesions. Real world registry data of this device and established evidence on the effect of cooling on localized tissue after thermal injury have been under review.

Purpose

To determine the safety of an oesophageal temperature control device by a review of real-world registry data on its clinical use during catheter ablation procedures and to clarify basic mechanisms of its therapeutic action by a literature review of scientific studies on cooling in the context of thermal injury.

Methods

The United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE), FDA Medical and Radiation Emitting Device Recalls, the Medicines and Healthcare products Regulatory Agency (MHRA) Medical Device Alerts and SwissMedic records of Field Safety Corrective Actions (FSCA) databases were reviewed for any device-related adverse events. A systematic literature review was conducted to clarify the findings from studies investigating the physiological processes behind the therapeutic effect of cooling after tissue thermal injury.

Results

Of over 20,000 oesophageal temperature control devices clinically used, 7976 were recorded as having been used for the purpose of oesophageal protection during left atrial catheter ablations. No adverse events occurred related to its use during left atrial catheter ablations. No case of clinically significant oesophageal injury was reported in a patient who had been protected by the oesophageal temperature control device. 208 research articles retrieved from PubMed and MEDLINE that met the search criteria were reviewed. The common finding in all the studies was that cooling had an anti-inflammatory and restorative effect via modulation of several immune-mediated pathways, local cellular function and genetic expression.

Conclusions

There have been no adverse events reported to date in real world clinical use of an oesophageal temperature control device during left atrial catheter ablations, for the purpose of active thermal protection. Literature review data suggests that there are complex biophysical and cellular effects from cooling that leads to its therapeutic effect but further work is required to define the mechanisms of action of thermal protection in this specific context.

Randomised comparison of achieve and traditional circular mapping catheters in cryoballoon ablation: results at up to a decade

Funding Acknowledgements

Type of funding sources: None.

Background

A single-centre trial randomised patients to the use of the Achieve mapping catheter or a traditional circular mapping catheter during cryoballoon procedures for paroxysmal atrial fibrillation (AF) in 2011-2014. Long-term outcomes from the cohort were determined in 2021.

Purpose

To evaluate the determinants of long-term outcome of ablation for paroxysmal AF.

Methods

Patient and study procedure characteristics and clinical outcomes were determined, including mapping catheter assignment, model of cryoballoon used, AF recurrence, repeat ablations required, findings at repeat ablation long term survival of the patient.

Results

Of 102 patients in the original study, 98 had long-term (4.11+/-2.82 years) follow up data available. 35 patients (35.7%) had AF recurrence, giving a long-term success rate at 64.3% after 1 ablation, increasing to 81.6% after repeat ablation. Of the study cohort n=8 (8.16%) died at a median of 4.9 years after ablation (IQR:1.7-5.7). 25/98 (25.5%) patients had a second ablation and 7 (7.1%) had a third or more ablations. Those who had AF recurrence were older, with a higher prevalence of prior ischaemic heart disease and cardiac device implantation (p=0.02-0.03). After multi-variate analysis, a prior implanted cardiac device was the only significant predictor of recurrence (p=0.03).

Conclusion

Long-term outcomes after a 1st time PAF cryoablation were similar regardless of the type of mapping catheter used, the generation of cryoballoon, and traditional procedure endpoints. AF recurrences were more often detected in older patients with a history of ischaemic heart disease and implanted cardiac devices.

Tunnelled dialysis catheter extraction: a cardiology experience

Funding Acknowledgements

Type of funding sources: None.

Background

Tunnelled dialysis catheters are integral to the management of patients with chronic kidney disease (CKD), providing a means to dialysis. They are prone to blockages necessitating removal. Most catheters are removed with manual traction without any sequalae by renal physicians whilst a small proportion require further intervention which may include interventional radiology or an ‘open’ surgical removal which carries additional risk. Cardiologists versed in transvenous lead extraction (TLE) provide an additional strategy.

Purpose

To evaluate the outcomes of tunnelled dialysis catheter ‘extractions’ performed by cardiologists at a high-volume TLE institute.

Method

All consecutive patients referred to cardiologists (1/10/2016 – 1/10/21) for extraction of tunnelled dialysis catheters following an unsuccessful attempt by the renal physicians and interventional radiology, were included in this series. Data of procedural outcomes was evaluated for safety and efficacy.

Results

Twelve patients (7 male) aged 64.15±15.04 years with a body mass index of 28.3 kg/m2 were referred for tunnelled catheter extraction for non-functioning lines (75%). Of these 12 CKD patients, the aetiology included focal segmental glomerulosclerosis (n=2), hypertension (n=2), diabetes (n=1) and sickle cell disease (n=1). In total, 12 tunnelled catheters (75%; n=9 right side) were completely removed (100%) using local anaesthesia (83.3%) in a procedure lasting 54.7±29.8 minutes and requiring 0.79±1.32 minutes of fluoroscopy. Eleven patients (91.7%) had their catheters successfully extracted with manual traction alone; 3 necessitated the use of a 0.035 stiff J-tip wire whilst one required the use of a rotational dissecting sheath Evolution (Cook Medical, USA). Of the 12 cases, 11 had a failed previous attempt including 1 patient who suffered a ventricular fibrillation cardiac arrest during the procedure and 1 was referred directly without an attempt as there was a concurrent pacemaker situated from the contralateral side; 4 patients had new lines placed and no significant complications occurred. There were no complications or procedural mortality.

Conclusion

Extraction of tunnelled dialysis catheter lines performed by cardiologists is safe and efficacious; experience in TLE is vital. This may provide an additional strategy for removal of these catheters when other percutaneous attempts fail.

COVID-19 opens the door for right iliac fossa pain treatment pathway

INTRODUCTION

The COVID-19 pandemic has increased the risks of surgery and management of common surgical conditions has changed, with greater reliance on imaging and conservative management. The negative appendectomy rate (NAR) in the UK has previously remained high. The aim of this study was to quantify pandemic-related changes in the management of patients with suspected appendicitis, including the NAR.

METHODS

A retrospective study was performed at a single high volume centre of consecutive patients aged over five years presenting to general surgery with right iliac fossa pain in two study periods: for two months before lockdown and for four months after lockdown. Pregnant patients and those with previous appendectomy, including right colonic resection, were excluded. Demographic, clinical, imaging and histological data were captured, and risk scores were calculated, stratifying patients into higher and lower risk groups. Data were analysed by age, sex and risk subgroups.

RESULTS

The mean number of daily referrals with right iliac fossa pain or suspected appendicitis reduced significantly between the study periods, from 2.92 before lockdown to 2.07 after lockdown (p<0.001). Preoperative computed tomography (CT) rates increased significantly from 22.9% to 37.2% (p=0.002). The NAR did not change significantly between study periods (25.5% prior to lockdown, 11.1% following lockdown, p=0.159). Twelve (75%) out of sixteen negative appendectomies were observed in higher risk patients aged 16-45 years who did not undergo preoperative CT. The NAR in patients undergoing CT was 0%.

CONCLUSIONS

Greater use of preoperative CT should be considered in risk stratified patients in order to reduce the NAR.

PROMET: The effect of operator profession on non-laser transvenous lead extraction

Funding Acknowledgements

Type of funding sources: None.

OnBehalf

PROMET group

Background

As implantation of cardiac implantable devices (CIED) rises globally, there is a paralleled need for extraction of these devices. Indications for transvenous lead extraction (TLE) is expanding, fuelling demand. This lifesaving procedure is performed by cardiologists and cardiac surgeons (CS). Cardiologists are familiar with transvenous methods whilst cardiac surgeons possess the skillset to address the significant complications associated with this procedure.

We compared non-laser TLE outcomes performed by cardiologists and cardiac surgeons from six high-volume extraction centres across Europe.

Methods

Data was collected retrospectively from six major European TLE centres of 2205 patients and 3849 leads (PROMET). Propensity 1:1 score matching (PSM) was performed to account for confounding variables. PSM model with variables: lead dwell time, infection indication, biventricular system and defibrillator device, was best matched. This dataset was analysed to compare outcomes of TLE performed by the cardiologists and CS. Predictors of 30-day mortality and complications were identified using a multivariate regression analysis.

Results

Patients treated by CS and cardiologists were similar in age (64.7 vs 66.7 years, p = NS) and equally male (70.3% vs 72.3%, p = 0.39) with a parallel infectious indication (51.7% vs 47.6%, p = 0.1). Surgeons achieved a significantly higher proportion of clinical success than cardiologists (98.9% vs 96.4%, p = 0.001) and complete lead extraction (98% vs 95.9%, p &lt; 0.01) with a higher rate of minor complications (4.1% vs 2.2%, p = 0.024); major complications were similar (0.9% vs 1.2%, respectively, p = 0.46) as was 30-day mortality (3.2% vs 2%, respectively, p = 0.28). Multivariate regression analysis revealed systemic infection (p &lt; 0.001, OR 7.2 [CI 2.3-20.1]) and defibrillator system extraction (p = 0.025, OR 3.4 [CI 1.2-10.2]) increased the odds of 30-day mortality, whilst Evolution™ sheath use reduced the odds (p = 0.025, OR 0.34 [CI 0.13-0.88]); lead dwell time (p = 0.02, OR 1.005 [1-1.009] and Evolution™ sheath use (p = 0.023, OR 2.15[1.1-4.15]) increased the odds of complications.

Conclusion

Cardiac surgeons and cardiologists achieved a high rate of TLE procedural success and with a similar safety profile, replicating standards seen across Europe.

PROMET: the effect of age on patient outcomes in non-laser transvenous lead extraction

Funding Acknowledgements

Type of funding sources: None.

OnBehalf

PROMET group

Background

Cardiac implantable electronic devices (CIEDs) improve morbidity and mortality. This has fuelled an upsurge in implantation of these devices across all patient cohorts, simultaneously increasing the need for transvenous lead extractions (TLE). As the global population expands and life-expectancy extends, TLE will play a significant role in CIED management. Advancing patient age is a recognised risk factor for poor outcomes however the association between patient age and TLE outcomes remains unclear. 

We sought to evaluate the relationship between patient age and non-laser TLE outcomes.

Method

Data of 2205 patients (3849 leads) was collected retrospectively from six high-volume TLE institutes across Europe (PROMET) between January 2005-December 2018. Propensity 1:1 score matching was performed to limit the effects of confounding variables, pairing 353 patients in the &gt;80 years of age category with 353 patients in &lt;80 years of age group. Procedural outcomes were compared between the two age groups and multivariate regression analysis was used for predictors of 30-day mortality.

Results

In the &lt;80 and &gt;80 years-of-age cohorts, there was a similar proportion of male patients (65.3% vs 67.9%, p = 0.47) treated under general anaesthesia (96.5% vs 93.4%, p = 0.078) for a pre-dominant infectious indication (56.7% vs 60.3%, p = 0.52) but with a higher requirement of the EvolutionTM sheath in the octogenarians (39.4% vs 48.4%, p = 0.015). A similar clinical success per lead was achieved between the two age groups (96.6% vs 98%, &lt;80 vs &gt;80 years, p = 0.245) as was complete lead extraction (95.5% vs 96.6%, &lt;80 vs &gt;80 years, p = 0.44) with a comparable minor complication rate (2.3% vs 3.1%, &lt;80 vs &gt;80 years, p = 0.29) and major complications (1.1% vs 1.4%, &lt;80 vs &gt;80 years, p = 0.74). Thirty-day mortality was higher in the octogenarian cohort than the &lt;80-year-olds without reaching statistical significance (5.4% vs 2.6%, p = 0.08); peri-procedural mortality was similar in both age groups (0.3% vs 0.6%, respectively, p = 0.56). Multivariate regression analysis revealed age (p = 0.013, OR 1.06 [1.01-1.12]), systemic infection (p = 0.026, OR 3.4 [1.16-10.35]) and lead dwell time (p = 0.007, OR 1.01 [1.003-1.017]) increased the odds of 30-day mortality.

Conclusion

Transvenous lead extraction is similar in efficacy and safety across all age groups. Thirty-day mortality is higher in the advanced age group, signifying the importance of post-procedural management in this cohort.

Transvenous lead revision for cardiac perforation: a single centre experience

Funding Acknowledgements

Type of funding sources: None.

Background

Cardiac perforation is an uncommon but life-threatening complication of cardiac implantable electronic device (CIED) implantation. Management strategy commonly relies on diagnostic Computed Tomography (CT) imaging and cardiac surgery. Emerging evidence has indicated a diversion from this approach. Transvenous culprit lead revision has been shown to be safe and efficacious in limited series.

We sought to evaluate the outcomes of transvenous lead revision in patients with cardiac perforation.

Method

Data was collected retrospectively of patients admitted to a single tertiary centre with CIED-related cardiac perforation between December 2013 – October 2019. Transvenous lead revision was performed as standard with cardiac surgery on standby. Patient demographics, use of CT imaging, method of removal and 30-day outcomes were recorded.

Results

Of the 46 recorded CIED-related cardiac perforations, the majority occurred in female patients (63%) and hypertensives (61%), whilst a proportion had cancer (20%) and ischaemic heart disease (30%). The culprit in most cases was a standard pacing lead (92%) of an active fixation (98%) in the right ventricle (80%) positioned at the ventricular apex (65%). The median time to presentation from implant was 14 days [IQR 4-50 days] with chest pain (44%); abnormal pacing indices was highly prevalent (95%) whilst a pericardial effusion was noted in the majority of cases (57%). CT scanning was performed in 19 cases (41%) for various indications but deemed essential in only 4, all of which had non-diagnostic pacing indices and imaging. Chest X-ray (CXR) found clear perforation, lead displacement or pleural effusion in 74% of cases, whilst an echocardiogram found these in 64% of cases. The culprit lead was replaced in the majority of cases (87%) under local anaesthesia (76%) with surgical backup. The median hospital stay was 7 days [IQR 3-10 days] with zero procedural and 30-day mortality.

Conclusion

Transvenous lead revision for CIED-related cardiac perforation is safe and efficacious. CT modality for diagnostic purposes is useful in providing incremental value in a minority of cases; patients with non-diagnostic pacing parameters and non-CT imaging benefit most from this.

A registry review of 2532 catheter ablations for atrial fibrillation using active thermal protection

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Dr Leung has received research support from Attune Medical (Chicago, IL). Dr Gallagher has received research funding from Attune Medical (Chicago, IL).

Background

  Thermal injury to the oesophagus causes a spectrum of adverse effects after ablation for atrial fibrillation (AF); at the most severe end, atrio-oesophageal fistula carries a high mortality rate. Controlled active thermal protection in the oesophagus during ablation is the most promising method of oesophageal protection. Randomized evidence from the IMPACT trial (NCT03819946) showed an 83.4% reduction in endoscopically detected oesophageal lesions compared to standard care when an oesophageal temperature control device was used to control the local temperature. The IMPACT patients who were randomized to the use of the device had no adverse event related to its use.  Real world registry data on applications of this device have not previously been available. 

Purpose

To determine the safety of an oesophageal temperature control device by review of real-world registry data on its clinical use and any reported device-related adverse events.

Methods

  We reviewed the following databases for any reported oesophageal temperature control device-related complications: The United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE), FDA Medical and Radiation Emitting Device Recalls, the Medicines and Healthcare products Regulatory Agency (MHRA) Medical Device Alerts and SwissMedic records of Field Safety Corrective Actions (FSCA). An internal registry (post-marketing follow up) database maintained by the manufacturer of the device was used to quantify the number used for each indication.  Reported events were reviewed and catalogued for description and identification of any events related to its use in the cardiac electrophysiology lab. The IMPACT study patients were reviewed for any device-related events.

Results

  Of the 13, 284 oesophageal temperature control devices used, 2532 were recorded as having been used for the purpose of oesophageal protection during catheter ablation for AF.  A total of 5 events associated with the device were identified, all from the MAUDE database.  Three were from 2017, one from 2018, and one from 2019.  All involved its use in critical care or trauma patients and were related to user error or contraindicated patient selection; none resulted in serious harm to the patient. No adverse events occurred related to its use in the cardiac electrophysiology lab. No case of clinically significant oesophageal injury was reported in a patient who had been protected by the oesophageal temperature control device.

Conclusions

Real world registry data has shown no adverse events reported to date in over 2500 uses of an oesophageal temperature control device in the cardiac electrophysiology lab, for the purpose of active thermal protection. This data supports the randomized trial evidence of its clinical effectiveness. Abstract Figure. Oesophageal active thermal protection

Combination anti-coronavirus therapies based on nonlinear mathematical models

Using nonlinear mathematical models and experimental data from laboratory and clinical studies, we have designed new combination therapies against COVID-19.

Patient outcomes after AF ablation using Ablation Index technology with oesophageal protection: insight from the IMPACT study

Background

Atrio-oesophageal fistula formation accounts for the majority of AF ablation-related morbidity and mortality. Thermal injury to the oesophagus can be significantly reduced by application of oesophageal cooling for protection during AF ablation. The effect of this method of oesophageal protection in patients receiving radiofrequency (RF) ablation guided by Ablation Index technology is currently unknown.

Objective

To investigate the ability of a temperature control device to protect the oesophagus from ablation-related thermal injury in patients receiving AF ablation guided by Ablation Index technology.

Methods

The IMPACT study is a single-centre, prospective, double-blind randomized controlled trial, which investigated the ability of a controlled method of oesophageal cooling to protect the oesophagus from ablation-related thermal injury. The EnsoETM device was used to deliver oesophageal cooling. This method was compared in a 1:1 randomization to a control group of standard practice utilizing a single-sensor temperature probe. In the study group, the device was used to keep the luminal temperature at 4°C during RF ablation. All participants received AF ablation using Ablation Index technology at posterior and anterior settings (30W at 350–400 and 40W at 450–500, respectively). Endoscopic examination was performed within 7 days post-ablation and oesophageal injury was graded. The patient and the endoscopist were blinded to the randomization. Structured clinical follow up occurred after 3 months post-ablation; both patient and follow up clinician were blinded.

Results

We recruited 188 patients, of whom 120 underwent endoscopic evaluation. Thermal injury to the mucosa was significantly more common in the control group than in those receiving oesophageal protection (12/60 versus 2/60; P=0.008). There was no difference between groups in RF time, lesion duration, force, power and combined ablation index (P value range= 0.2–0.9). Procedure and fluoroscopy duration were similar (P=0.97, P=0.91 respectively). The majority of those who passed through the 1st follow up evaluation (n=136) did not have gastrointestinal or chest pain symptoms post ablation and there was no difference between the randomized groups. Only 4.4% overall had severe symptoms and they were poorly correlated against those who sustained mucosal lesions. AF recurrence was similar in both groups (8% vs 8.8%). There were 2 cases of vascular trauma needing intervention in the control group and 1 case of conservatively managed pericardial effusion in the protected group only. Clinical and endoscopy findings did not report any EnsoETM device-related trauma.

Conclusion

Thermal protection of the oesophagus significantly reduces ablation-related thermal injury compared to standard care when ablation is performed using radiofrequency with Ablation Index technology. This method of oesophageal protection is safe and does not compromise the efficacy of the ablation procedure.

Endoscopy findings and patient symptoms.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): 1. Public hospital: St. George's NHS Foundation Trust; 2. Private company: Attune Medical (Chicago, IL)

Potential of exocellular carbohydrate antigens of Staphylococcus epidermidis in the serodiagnosis of orthopaedic prosthetic infection

The potential of exocellular carbohydrate antigens of Staphylococcus epidermidis as markers of infection in bone was investigated by immunoblotting and enzyme-linked immunosorbent assay (ELISA). Exocellular antigens were prepared by gel filtration chromatography of concentrated brain heart infusion culture supernates. The antigenic material appeared as diffuse bands between 24 and 32 kDa on the immunoblots and was not susceptible to digestion with trypsin, indicating that the response in the patients was to non-protein (polysaccharide or teichoic acid, or both) exocellular material. Significant differences were detected between the immunoblot antigen profiles for serum IgG from patients with S. epidermidis bone infection and those with an uninfected prosthetic joint. Thirteen of 16 patients with S. epidermidis prosthetic joint infection showed an elevated serum IgG level by ELISA compared with controls with uninfected joints. However, the antigen was not specific for S. epidermidis bone infection; high levels of IgG were also detected in patients with other serious staphylococcal and streptococcal infections. The ELISA test may be valuable in distinguishing between staphylococcal infection of joints and aseptic loosening by excluding cases of infection.