Machine learning to predict early recurrence after oesophageal cancer surgery.

BACKGROUND: Early cancer recurrence after oesophagectomy is a common problem, with an incidence of 20-30 per cent despite the widespread use of neoadjuvant treatment. Quantification of this risk is difficult and existing models perform poorly. This study aimed to develop a predictive model for early recurrence after surgery for oesophageal adenocarcinoma using a large multinational cohort and machine learning approaches. METHODS: Consecutive patients who underwent oesophagectomy for adenocarcinoma and had neoadjuvant treatment in one Dutch and six UK oesophagogastric units were analysed. Using clinical characteristics and postoperative histopathology, models were generated using elastic net regression (ELR) and the machine learning methods random forest (RF) and extreme gradient boosting (XGB). Finally, a combined (ensemble) model of these was generated. The relative importance of factors to outcome was calculated as a percentage contribution to the model. RESULTS: A total of 812 patients were included. The recurrence rate at less than 1 year was 29·1 per cent. All of the models demonstrated good discrimination. Internally validated areas under the receiver operating characteristic (ROC) curve (AUCs) were similar, with the ensemble model performing best (AUC 0·791 for ELR, 0·801 for RF, 0·804 for XGB, 0·805 for ensemble). Performance was similar when internal-external validation was used (validation across sites, AUC 0·804 for ensemble). In the final model, the most important variables were number of positive lymph nodes (25·7 per cent) and lymphovascular invasion (16·9 per cent). CONCLUSION: The model derived using machine learning approaches and an international data set provided excellent performance in quantifying the risk of early recurrence after surgery, and will be useful in prognostication for clinicians and patients.

ANTECEDENTES: la recidiva precoz del cáncer tras esofaguectomía es un problema frecuente con una incidencia del 20-30% a pesar del uso generalizado del tratamiento neoadyuvante. La cuantificación de este riesgo es difícil y los modelos actuales funcionan mal. Este estudio se propuso desarrollar un modelo predictivo para la recidiva precoz después de la cirugía para el adenocarcinoma de esófago utilizando una gran cohorte multinacional y enfoques con aprendizaje automático. MÉTODOS: Se analizaron pacientes consecutivos sometidos a esofaguectomía por adenocarcinoma y que recibieron tratamiento neoadyuvante en 6 unidades de cirugía esofagogástrica del Reino Unido y 1 de los Países Bajos. Con la utilización de características clínicas y la histopatología postoperatoria se generaron modelos mediante regresión de red elástica (elastic net regression, ELR) y métodos de aprendizaje automático Random Forest (RF) y XG boost (XGB). Finalmente, se generó un modelo combinado (Ensemble) de dichos métodos. La importancia relativa de los factores respecto al resultado se calculó como porcentaje de contribución al modelo. RESULTADOS: En total se incluyeron 812 pacientes. La tasa de recidiva a menos de 1 año fue del 29,1%. Todos los modelos demostraron una buena discriminación. Las áreas bajo la curva ROC (AUC) validadas internamente fueron similares, con el modelo Ensemble funcionando mejor (ELR = 0,791, RF = 0,801, XGB = 0,804, Ensemble = 0,805). El rendimiento fue similar cuando se utilizaba validación interna-externa (validación entre centros, Ensemble AUC = 0,804). En el modelo final, las variables más importantes fueron el número de ganglios linfáticos positivos (25,7%) y la invasión linfovascular (16,9%). CONCLUSIÓN: El modelo derivado con la utilización de aproximaciones con aprendizaje automático y un conjunto de datos internacional proporcionó un rendimiento excelente para cuantificar el riesgo de recidiva precoz tras la cirugía y será útil para clínicos y pacientes a la hora de establecer un pronóstico.

Multicentre cohort study to define and validate pathological assessment of response to neoadjuvant therapy in oesophagogastric adenocarcinoma.

BACKGROUND: This multicentre cohort study sought to define a robust pathological indicator of clinically meaningful response to neoadjuvant chemotherapy in oesophageal adenocarcinoma. METHODS: A questionnaire was distributed to 11 UK upper gastrointestinal cancer centres to determine the use of assessment of response to neoadjuvant chemotherapy. Records of consecutive patients undergoing oesophagogastric resection at seven centres between January 2000 and December 2013 were reviewed. Pathological response to neoadjuvant chemotherapy was assessed using the Mandard Tumour Regression Grade (TRG) and lymph node downstaging. RESULTS: TRG (8 of 11 centres) was the most widely used system to assess response to neoadjuvant chemotherapy, but there was discordance on how it was used in practice. Of 1392 patients, 1293 had TRG assessment; data were available for clinical and pathological nodal status (cN and pN) in 981 patients, and TRG, cN and pN in 885. There was a significant difference in survival between responders (TRG 1-2; median overall survival (OS) not reached) and non-responders (TRG 3-5; median OS 2·22 (95 per cent c.i. 1·94 to 2·51) years; P < 0·001); the hazard ratio was 2·46 (95 per cent c.i. 1·22 to 4·95; P = 0·012). Among local non-responders, the presence of lymph node downstaging was associated with significantly improved OS compared with that of patients without lymph node downstaging (median OS not reached versus 1·92 (1·68 to 2·16) years; P < 0·001). CONCLUSION: A clinically meaningful local response to neoadjuvant chemotherapy was restricted to the small minority of patients (14·8 per cent) with TRG 1-2. Among local non-responders, a subset of patients (21·3 per cent) derived benefit from neoadjuvant chemotherapy by lymph node downstaging and their survival mirrored that of local responders.

Flavor variability and flavor stability of U.S.-produced whole milk powder.

Flavor variability and stability of U.S.-produced whole milk powder (WMP) are important parameters for maximizing quality and global competitiveness of this commodity. This study characterized flavor and flavor stability of domestic WMP. Freshly produced (<1 mo) WMP was collected from 4 U.S. production facilities 5 times over a 1 y period. Each sample was analyzed initially and every 2 mo for sensory profile, volatiles, color, water activity, and moisture through 12 mo storage. Selected volatiles were quantified using solid phase microextraction (SPME) with gas chromatography/mass-spectrometry: dimethyl sulfide, 2-methylbutanal, 3-methylbutanal, hexanal, 2-heptanone, heptanal, 1-octen-3-ol, octanal, 3-octen-2-one, and nonanal. Multiple linear regression with backwards elimination was applied to generate equations to predict grassy and painty flavors based on selected volatiles. All WMP were between 2% and 3% moisture and 0.11 and 0.25 water activity initially. WMP varied in initial flavor profiles with varying levels of cooked, milk fat, and sweet aromatic flavors. During storage, grassy and painty flavors developed while sweet aromatic flavor intensities decreased (P < 0.05). Painty and grassy flavors were confirmed by increased levels (P < 0.05) of lipid oxidation products such as hexanal, heptanal, and octanal. Hexanal, 2-heptanone, 1-octen-3-ol, and nonanal concentrations were best predictors of grassy flavor (R(2)= 0.38, P < 0.0001) while hexanal, 2-methylbutanal, 3-methylbutanal, octanal, and 3-octen-2-one concentrations were best predictors of painty flavor (R(2)= 0.61, P < 0.0001). These results provide baseline information to determine specific factors that can be controlled to optimize U.S. WMP flavor and flavor stability.

Effect of nitrogen flushing and storage temperature on flavor and shelf-life of whole milk powder.

The US industry standard for shelf-life of whole milk powder (WMP) is 6 to 9 mo, although previous research has demonstrated flavor changes by 3 mo at ambient storage. This study evaluated the influence of packaging atmosphere, storage temperature, and storage time on WMP shelf-life using sensory and instrumental techniques. Two commercial batches of WMP were repackaged in plastic laminate pouches with air or nitrogen and stored at 2 degrees C or 23 degrees C for 1 yr. Descriptive analysis was conducted using a 10-member trained panel; volatile analysis was performed using solid-phase microextraction with gas chromatography-mass spectrometry. Consumer acceptance (n = 75) was conducted every 3 mo with reconstituted WMP and white and milk chocolate made from each treatment. Data were analyzed using ANOVA with Fisher's LSD, Pearson correlation analysis, and principal component analysis. Air-stored WMP had higher peroxide values, lipid oxidation volatiles, and grassy and painty flavors than nitrogen-flushed WMP. Storage temperature did not affect levels of straight chain lipid oxidation volatiles; 23 degrees C storage resulted in higher cooked and milkfat flavors and lower levels of grassy flavor compared with 2 degrees C storage. Consumer acceptance was negatively correlated with lipid oxidation volatiles and painty flavor. Nitrogen flushing prevented the development of painty flavor in WMP stored up to 1 yr at either temperature, resulting in chocolate with high consumer acceptance. Nitrogen flushing can be applied to extend the shelf life of WMP for use in chocolate; storage temperature also plays a role, but to a lesser extent.

Quality at time of purchase of dried milk products commercially packaged in reduced oxygen atmosphere.

Nonfat dry milk (NDM) and powdered whey beverages are available at the retail level, packaged in No. 10 cans in a reduced oxygen atmosphere to prolong shelf life. The objective of this research was to determine the sensory and nutritional quality of these dried milk products at the time of purchase. In the 10 brands tested, wide variation existed in headspace oxygen, can seam quality, sensory quality, and vitamin A (with 6 of 10 brands entirely lacking the vitamin). Manufacturers of dried milk products packaged in cans for long-term storage need to give careful attention to can seam quality, product labeling, and vitamin fortification. Consumers would be well advised to evaluate several brands of dried milk products prior to large quantity purchases.

Left ventricular and biventricular pacing in congestive heart failure.

Dual-chamber pacing improved hemodynamics acutely in a subset of patients with left ventricular (LV) dysfunction but conveyed no long-term symptomatic benefit in most. More recently, LV pacing and biventricular (multisite) pacing have been used to improve systolic contractility by altering the electrical and mechanical ventricular activation sequence in patients with severe congestive heart failure (CHF) and intraventricular conduction delay or left bundle branch block (LBBB). Intraventricular conduction delay and LBBB cause dyssynchronous right ventricular and LV contraction and worsen LV dysfunction in cardiomyopathies. Both LV and biventricular cardiac pacing are thought to improve cardiac function in this situation by effecting a more coordinated and efficient ventricular contraction. Short-term hemodynamic studies have shown improvement in LV systolic function, which seems more pronounced with monoventricular LV pacing than with biventricular pacing. Recent clinical studies in limited numbers of patients suggest long-term clinical benefit of biventricular pacing in patients with severe CHF symptoms. Continuing and future studies will demonstrate whether and in which patients LV and biventricular pacing are permanently effective and equivalent and which pacing site within the LV produces the most beneficial hemodynamic results.

Long-term survival after ablation of the atrioventricular node and implantation of a permanent pacemaker in patients with atrial fibrillation.

BACKGROUND: In patients with atrial fibrillation that is refractory to drug therapy, radio-frequency ablation of the atrioventricular node and implantation of a permanent pacemaker are an alternative therapeutic approach. The effect of this procedure on long-term survival is unknown. METHOD: We studied all patients who underwent ablation of the atrioventricular node and implantation of a permanent pacemaker at the Mayo Clinic between 1990 and 1998. Observed survival was compared with the survival rates in two control populations: age- and sex-matched members of the Minnesota population between 1970 and 1990 and consecutive patients with atrial fibrillation who received drug therapy in 1993. RESULTS: A total of 350 patients (mean [+/-SD] age, 68+/-11 years) were studied. During a mean of 36+/-26 months of follow-up, 78 patients died. The observed survival rate was significantly lower than the expected survival rate based on the general Minnesota population (P<0.001). Previous myocardial infarction (P<0.001), a history of congestive heart failure (P=0.02), and treatment with cardiac drugs after ablation (P=0.03) were independent predictors of death. Observed survival among patients without these three risk factors was similar to expected survival (P=0.43). None of the 26 patients with lone atrial fibrillation died during follow-up (37+/-27 months). The observed survival rate among patients who underwent ablation was similar to that among 229 controls with atrial fibrillation (mean age, 67+/-12 years) who received drug therapy (P=0.44). CONCLUSIONS: In the absence of underlying heart disease, survival among patients with atrial fibrillation after ablation of the atrioventricular node is similar to expected survival in the general population. Long-term survival is similar for patients with atrial fibrillation, whether they receive ablation or drug therapy. Control of the ventricular rate by ablation of the atrioventricular node and permanent pacing does not adversely affect long-term survival.

Is there an adverse outcome from abandoned pacing leads?

BACKGROUND: Indications for extraction of an abandoned pacemaker lead (APL) are controversial. The purpose of this study was to determine whether or not APLs should be extracted in the absence of pacemaker-related problems. METHODS AND RESULTS: We retrospectively reviewed, from 1977 through 1998, all patients with retained, non-functional leads and identified 433-266 males and 167 females. Mean age at initial pacemaker implantation was 68[emsp4 ]years. These patients received a total of 259 atrial and 948 ventricular leads. Of the total of 1,207 leads, 611 became non-functional. A total of 531 non-functional leads were abandoned, of which 18 were later extracted: one APL in 345 patients, two in 78, and three in 10. Indications for new lead placement when non-functional leads were abandoned included capture and/or sensing failure (243), lead recall (177), lead fracture (86), pacing system replacement to the contralateral side (11), accommodating patient growth (5), pacemaker function upgrade (5), replacement with implantable cardioverter defibrillator (ICD, 2), interference with ICD (1), and unknown (1). Complications that were associated with pacemakers were found in 24 patients (5.5%)-pacemaker system infection (8 patients) and venous occlusion at the time of a subsequent procedure of new lead placement when APLs had already been in place (16) which resulted in APL extraction (7) or transfer of the pacemaker system to the contralateral side (9). Neither venous thrombosis nor other complications were found in the remaining 409 patients (94.5%). The incidence of complications was higher in patients with three APLs than in patients with two or fewer APLs (40% vs. 4.7%, P=1x10(-6)), in patients with four or more total lead implantations than in patients with three or fewer total lead implantations (26.2% vs. 0. 6%, P<1x10(-10)), and in patients with three or more procedures of new lead placements than in patients with two or fewer procedures of new lead placements (36.4% vs. 3.9%, P=1x10(-10)). Patients with complications were younger than those without complications both at the time of initial pacemaker implantation (59+/-16 vs. 68+/-17 y, P=0.01) and when non-functional leads were abandoned (63+/-15 vs. 71+/-16 y, P=0.04). Mean numbers of APLs, total leads implanted, and procedures of new lead placement were significantly larger in patients with complications than in those without complications (1.58+/-0.78 vs. 1.2+/-0.44, 4.96+/-1.23 vs. 2.66+/-0.8, and 2.13+/-0.85 vs. 1.25+/-0.53, P=0.03, 4x10(-9) and 4x10(-5), respectively). CONCLUSIONS: 1. With only 5.5% of patients having had pacemaker-related complications, the adverse outcome of APL is small. 2. Clinical clues to the possible occasion for pacemaker-related complications include three or more APLs, four or more total leads, three or more procedures of new lead placement, and a younger age at initial pacemaker implantation. 3. Patients with a large number of APLs, total lead implantations, and procedures of new lead placement should be carefully observed to detect possible pacemaker-associated complications.

Dual chamber pacing for patients with hypertrophic obstructive cardiomyopathy: a clinical perspective in 2000.

In some patients with hypertrophic cardiomyopathy, the dynamic left ventricular outflow tract obstructive gradient results in exercise-limiting symptoms of dyspnea, angina, and syncope. Dual chamber pacing has been proposed as a widely available alternative treatment for a subset of patients with symptomatic hypertrophic obstructive cardiomyopathy. Initial studies showed a reduction in gradient and an improvement in symptoms in almost 90% of patients with severe symptoms. We report the Mayo Clinic experience with dual chamber pacing in 38 patients with hypertrophic obstructive cardiomyopathy who had permanent pacemakers implanted for limiting symptoms intractable to medical therapy. After a mean +/- SD follow-up of 24 +/- 14 months, subjective improvement was reported in 47% of patients. However, there was no statistical difference between the maximal oxygen consumption at last follow-up and AAI pacing (atrial sensing and atrial pacing) (18.6 +/- 1.1 mL.kg-1.min-1) (i.e., when the pacemaker was implanted but not pacing continuously). This article discusses the clinical perspective on the utility of dual chamber pacing for patients with hypertrophic obstructive cardiomyopathy.

Randomized clinical trial of the 350-mm2 versus the 500-mm2 Baerveldt implant: longer term results: is bigger better?

OBJECTIVE: To report the longer term results of a randomized, clinical trial comparing the 350-mm2 and the 500-mm2 Baerveldt glaucoma implants. DESIGN: Extended follow-up on a randomized, controlled trial. PARTICIPANTS: Between March 1991 and April 1993, 107 patients with uncontrolled intraocular pressure (IOP) due to non-neovascular glaucoma associated with aphakia, pseudophakia, or failed filters were randomly assigned for surgical placement of either the 350-mm or the 500-mm2 Baerveldt implant at the Doheny Eye Institute. METHODS: A random-numbers table was used to assign each patient to one of the two groups. Preoperative IOPs and visual acuities were recorded. Clinical records were reviewed to ascertain postoperative IOPs, visual acuities, number of medications used, and implant-related complications that occurred throughout the follow-up period. MAIN OUTCOME MEASURES: Success was defined as IOP of 6 mmHg or greater and of 21 mmHg or less in two or more consecutive follow-up visits without further glaucoma surgery or loss of light perception attributable to glaucoma. RESULTS: The overall success rates were 87% for the 350-mm2 group and 70% for the 500-mm2 group (P = 0.05). Average follow-up was 37 months (range, 1-76 months) for the 350-mm2 group and 34 months (range, 5-77 months) for the 500-mm2 group. The life-table success rates declined over time for both implant groups, from a high of 98% for the 350-mm2 group and 92% for the 500-mm2 group at 1 year to a cumulative success rate of 79% for the 350-mm2 group and 66% for the 500-mm2 group at 5 years. Visual acuities were better or remained the same in 50% of the patients in the 350-mm2 group and 46% of those in the 500-mm2 group. Complications during the 5-year follow-up were also statistically similar. CONCLUSIONS: The longer term results show that the 350-mm2 Baerveldt implant is more successful than the 500-mm2 implant for overall IOP control. Interval comparisons indicate a higher rate of success for the 350-mm2 implant in the first, second, third, fourth, and fifth years of implantation. Visual acuities, implant-related complications, and average IOPs were statistically indistinguishable between the two groups.

Risks of spontaneous injury and extraction of an active fixation pacemaker lead: report of the Accufix Multicenter Clinical Study and Worldwide Registry.

BACKGROUND: The Telectronics Accufix pacing leads were recalled in November 1994 after 2 deaths and 2 nonfatal injuries were reported. This multicenter clinical study (MCS) of patients with Accufix leads was designed to determine the rate of spontaneous injury related to the J retention wire and results of lead extraction. METHODS AND RESULTS: The MCS included 2589 patients with Accufix atrial pacing leads that were implanted at or who were followed up at 12 medical centers. Patients underwent cinefluoroscopic imaging of their lead every 6 months. The risk of J retention wire fracture was approximately 5.6%/y at 5 years and 4.7%/y at 10 years after implantation. The annual risk of protrusion was 1.5%. A total of 40 spontaneous injuries were reported to a worldwide registry (WWR) that included data from 34 672 patients (34 892 Accufix leads), including pericardial tamponade (n=19), pericardial effusion (n=5), atrial perforation (n=3), J retention wire embolization (n=4), and death (n=6). The risk of injury was 0.02%/y (95% CI, 0.0025 to 0. 072) in the MCS and 0.048%/y (95% CI, 0.035 to 0.067) in the WWR. A total of 5299 leads (13%) have been extracted worldwide. After recall in the WWR, fatal extraction complications occurred in 0.4% of intravascular procedures (16 of 4023), with life-threatening complications in 0.5% (n=21). Extraction complications increased with implant duration, female sex, and J retention wire protrusion. CONCLUSIONS: Accufix pacing leads pose a low, ongoing risk of injury. Extraction is associated with substantially higher risks, and a conservative management approach is indicated for most patients.

Annular peripheral choroidal detachment simulating aqueous misdirection after glaucoma surgery.

PURPOSE: The purpose of the study was to define a newly recognized complication after glaucoma surgery and to recommend a therapeutic regimen. METHODS: Eighteen patients diagnosed initially as having aqueous misdirection after glaucoma surgery, but who subsequently were found by ultrasonography to have an annular peripheral choroidal detachment that resulted in secondary angle closure glaucoma, were studied. Ten of these patients were treated with topical cycloplegics and corticosteroids, and 8 were treated with drainage of suprachoroidal fluid. Outcomes of these two treatment methods were compared. RESULTS: Annular peripheral choroidal detachment reliably was diagnosed with ultrasonography. Of the variables studied, time elapsed before resolution of the annular peripheral choroidal detachment was noted to be statistically significant (P < 0.00005). Immediate resolution followed drainage of suprachoroidal fluid, whereas a mean of 19.6 days was required for resolution after medical therapy. CONCLUSIONS: Annular peripheral choroidal detachment should be considered in the differential diagnosis of a flat or shallow anterior chamber with normal or high intraocular pressure after glaucoma surgery. The diagnosis of annular peripheral choroidal detachment can be confirmed most reliably by ultrasonography. Medical therapy is as effective as is surgery, although a significantly longer time to resolution is required.

Long-term histologic studies of the Baerveldt implant in a rabbit model.

PURPOSE: The Baerveldt glaucoma implant is an aqueous shunting device with large surface area that is installed through a single-quadrant conjunctival incision. A rabbit model of the Baerveldt implant was created to obtain serial histology and clinical information over 1 year. METHODS: Modified versions of the Baerveldt implant (110 or 160 mm2) were implanted in 18 normal New Zealand white rabbit eyes. The rabbits were examined periodically and their intraocular pressures (IOPs) recorded. They were killed at monthly intervals to obtain histology of the bleb capsules. RESULTS: Thin capsules were present at 1 month, which consisted of lamellar collagen deposition surrounded by a granulomatous reaction with multinucleate giant cells. Inflammatory cells (probably macrophages) were scattered on the inner bleb surface. The granulomatous reaction resolved after 4 months. Subsequently, capsule thickness and cellularity remained relatively stable, although the collagen stroma became less compact over time. Sixteen rabbit eyes had initial IOP reductions of > or = 3 mm Hg compared with fellow eyes, which persisted up to 4 weeks postoperatively. Seven eyes (39%) exhibited a hypertensive phase (IOP exceeded that of fellow eye by > or = 3 mm Hg) from 2 weeks to 3 months postoperatively. CONCLUSION: The Baerveldt explant is surrounded by a fibrous capsule that matures over time. The bleb histology in the rabbit model is similar to that described with the Molteno implant in primates and humans, except for the eventual development of a fibroblastic inner lining in the rabbit model. This contrasts with primate and human models, in which the inner lining remains an open mesh.

Planarity of nitro-substituted phenothiazines.

The structures of three nitro-substituted phenothiazines [1,3,4-trifluoro-2-nitrophenothiazine, 10-(4-chlorobutyl)-1,3,4-trifluoro-2-nitrophenothiazine and 10-(4-chlorobutyl)-3-nitrophenothiazine] have been determined. The first of these red compounds forms infinite stacks in the solid state, in which donor and acceptor regions of the approximately planar molecules alternate. The molecules of the other two compounds, which have folded, or 'butterfly', conformations in the solid state, do not form stacks, presumably because the bulky chlorobutyl substituents cannot be accommodated. The very dark color of solid 3-nitrophenothiazine suggests the presence of extended molecular stacks, but crystals suitable for a structure determination could not be obtained.

Suprachoroidal hemorrhage after Molteno implantation.

PURPOSE: The objective of this study is to identify the rate and the associated risk factors for suprachoroidal hemorrhage (SCH) after Molteno drain implantation. METHODS: Data from the Molteno pilot study and single versus double-plate Molteno study were reviewed retrospectively for the occurrence of SCH. Follow-up intervals, demographic variables, ocular data, and medical history were collected. RESULTS: SCH occurred in 6% of the patients enrolled in the Molteno studies; all cases were delayed and none were intraoperative. Significantly associated factors in a multiple logistic regression for SCH were the extent of intraocular pressure (IOP) drop after surgery, the post-operative IOP, a diagnosis of angleclosure glaucoma, and possibly the number of prior surgeries as well. Eyes with SCH did significantly less well in terms of visual acuity outcomes and were more likely to have inadequately controlled IOP. CONCLUSIONS: This study suggests that SCH occurs at the same frequency after Molteno implantation as after filtering surgery with antimetabolite use and that eyes with SCH do less well.

Serial fluoroscopic evaluation of a pacing lead.

A recall of the Telectronics Accufix 330-801 atrial lead was issued in November 1994, because of fracture of the "J"-shaped retention wire. To assess the integrity of the retention wire, we have performed fluoroscopic screening on 209 patients with the Accufix 330-801 atrial lead in place. Cine films of all 135 patients originally classified as normal were reevaluated after the original screening. Eighty patients have undergone two serial fluoroscopic evaluations separated by 158 +/- 5.4 days. Nine retention wires originally classified as normal were reclassified as fracture without protrusion, and two were reclassified as fracture with protrusion when the original films were reevaluated. Eight of the 11 leads reclassified were screened during our first 2 days of fluoroscopic evaluation of this lead. Of the 80 patients who underwent a second fluoroscopic screening, 70 were initially classified as normal (9 of which were reclassified as described above), 1 fractured, and 9 indeterminate. There were no new fractures detected in this group, and the fractured retention wires did not appear to change during this observation period. We conclude that there is a definite learning curve associated with fluoroscopic evaluation of this lead, and continue to recommend that screening be performed by cardiologists experienced in fluoroscopic screening. Fractured retention wires remained stable in appearance during this observation time. No new retention wire fractures were detected; however, longer follow-up will be required before the incidence of retention wire fracture can be determined.

Extraction of the Telectronics Accufix 330-801 atrial lead: the Mayo Clinic experience.

OBJECTIVE: To document a cumulative experience with removal of the Telectronics 330-801 Accufix atrial lead after it was withdrawn from the market. DESIGN: We reviewed our results with 96 attempted lead extraction procedures through Dec. 1, 1995. MATERIAL AND METHODS: All patients underwent preoperative assessment, including fluoroscopic screening of the lead. Patients had blood typing and screening done before the extraction procedure, and extractions were performed with cardiac surgical intervention available. Pacing dependence was assessed to determine the need for temporary pacing. RESULTS: The mean patient age was 65.7 +/- 1.6 years and the mean duration of lead implantation was 31.0 +/- 1.4 months. Of the 96 lead extractions attempted, 94 were successful. Of the 96 cases, the retention wires were normal in 29, fractured without protrusion in 34, and fractured with protrusion in 33. Fifty-three leads were removed with use of simple traction only, and seven leads were removed by using a locking stylet and telescoping sheaths. The Cook workstation was used in the removal of 32 leads through the femoral vein; in 1 of these 32 patients, the retention wire was removed before lead extraction. The retention wire was removed but the lead was left intact in one patient. One lead was removed during an opertive maze procedure. Associated complications were minimal. CONCLUSION: Although lead extraction is a potentially fatal procedure, the Telectronics 330-801 Accufix atrial lead can be extracted safely with minimal morbidity when performed by experienced personnel.

Atrial "J" pacing lead retention wire fracture: radiographic assessment, incidence of fracture, and clinical management.

UNLABELLED: In November 1994, Telectronics Pacing Systems issued a voluntary recall of their Accufix 330-801 and 329-701 "J"-shaped atrial pacemaker leads. To assess the integrity of the lead, 156 consecutive patients with the Accufix 330-801 atrial lead implanted underwent fluoroscopic screening. Leads were visualized in at least two orthogonal views. When identified, fractured retention wires were classified into one of four groups, depending on the degree of wire extrusion outside of the lead insulation. RESULTS: Of the 156 patients, 35 patients (22.4%) had a definite retention wire fracture, and an additional 13 patients (8.3%) had indeterminate leads. Neither the age of the patients, the time since lead implant, nor the site of fracture correlated with the incidence of wire fracture. When analyzed to include indeterminate leads that were re-evaluated and found to be fractured, as well as two leads that were identified as being radiographically normal but found to be fractured after extraction, the incidence of retention wire fracture is 25.6% (40 of 156 leads evaluated). CONCLUSIONS: The incidence of retention wire fracture in the Accufix 330-801 lead is significantly higher than originally reported. Patients should be notified of the potential dangers associated with this lead. Cardiac digital fluoroscopy is an effective method of screening for wire fracture. Leads with fractured retention wires should be extracted and those with normal fluoroscopic appearance should undergo regular fluoroscopic screening.

Snare removal of a telectronics accufix atrial J retention wire.

A voluntary recall of the Telectronics Accufix models 330-801 and 329-701 "J"-shaped atrial pacemaker leads has been issued because of fracture and extrusion of the J-shaped retention wire. Such extrusion can result in laceration of the atrium or surrounding vascular structures. Herein we describe a patient with a fractured and extruded retention wire that was snared and removed percutaneously; the atrial lead was left intact, and pacing function was satisfactory. This unique procedure can be used to avoid the morbidity associated with percutaneous lead extraction or thoracotomy and to prevent potential dislodgment and embolization of the retention wire during lead extraction.