Tomografía computarizada en el posoperatorio de cirugía abdominal mayor / Computed tomography scan after major abdominal surgery

RESUMEN Antecedentes: las cirugías abdominales mayores pueden presentar complicaciones posoperatorias graves cuya detección temprana resulta importante para su tratamiento. Objetivo: determinar la utilidad del uso de la tomografía computarizada (TC) para el diagnóstico temprano de las complicaciones de cirugía abdominal mayor. Materiales y métodos: estudio retrospectivo observacional descriptivo, mediante revisión de historias clínicas de pacientes operados de cirugía abdominal mayor en un Hospital Privado. Se agruparon los pacientes según presentaban o no síntomas sospechosos de complicación posoperatoria. Los primeros se clasificaron en 3 grupos: sin TC, con TC con hallazgos positivos y con TC sin hallazgos patológicos. Resultados: se analizaron 154 pacientes, con un promedio de edad de 61,3 ± 12,5 años; 83 (54%) fueron varones. Sobre 48 pacientes (31%) con síntomas sospechosos de complicaciones, fueron reoperados 6 sin TC, pero con síntomas muy evidentes, 7 con signos tomográficos positivos y 14/41 del grupo con TC negativa. Todos tuvieron hallazgos que justificaron la intervención. Hubo 27 casos (17,5%) con complicaciones IIIb según Clavien-Dindo y 3 pacientes (2%) fallecieron. Conclusión: la tomografía computarizada tuvo valor para confirmar una complicación, pero no para descartarla. Los parámetros clínicos cobran especial importancia en los pacientes sintomáticos sin hallazgos patológicos en la TC posoperatoria.

ABSTRACT Background: Major abdominal surgeries may present serious postoperative complications that require early diagnosis. Objective: The aim of this study was to determine the usefulness of computed tomography (CT) for the early diagnosis of major abdominal surgery complications. Material and methods: We conducted a retrospective, observational and descriptive study using data obtained from the medical records of patients undergoing major abdominal surgery in a private hospital. Patients were divided into two groups according to the presence or absence of symptoms suggesting a postoperative complication. Patients with symptoms were classified into 3 groups: without CT, with CT with positive findings and with CT without abnormal findings. Results: A total of 154 patients were analyzed; mean age was 61.3 ± 12.5 years and 83 (54%) were male. Of 48 patients (31%) with symptoms suggestive of complications, 6 had very evident symptoms and were re-operated without CT, 7 had positive findings on CT and CT was negative in 14/41. All the patients had findings that supported the decision to re-operate. There were 27 cases (17.5%) with grade 3b complications of the Clavien-Dindo classification and 3 patients (2%) died. Conclusion: Computed tomography was useful to confirm a complication, but not to rule it out. Clinical parameters remain of utmost importance in patients with symptoms and absence of abnormal findings in post-operative CT.

Risk of caesarean delivery in labour induction: a systematic review and external validation of predictive models.

BACKGROUND: Despite the existence of numerous published models predicting the risk of caesarean delivery in women undergoing induction of labour (IOL), validated models are scarce. OBJECTIVES: To systematically review and externally assess the predictive capacity of caesarean delivery risk models in women undergoing IOL. SEARCH STRATEGY: Studies published up to 15 January 2021 were identified through PubMed, CINAHL, Scopus and ClinicalTrials.gov, without temporal or language restrictions. SELECTION CRITERIA: Studies describing the derivation of new models for predicting the risk of caesarean delivery in labour induction. DATA COLLECTION AND ANALYSIS: Three authors independently screened the articles and assessed the risk of bias (ROB) according to the prediction model risk of bias assessment tool (PROBAST). External validation was performed in a prospective cohort of 468 pregnancies undergoing IOL from February 2019 to August 2020. The predictive capacity of the models was assessed by creating areas under the receiver operating characteristic curve (AUCs), calibration plots and decision curve analysis (DCA). MAIN RESULTS: Fifteen studies met the eligibility criteria; 12 predictive models were validated. The quality of most of the included studies was not adequate. The AUC of the models varied from 0.520 to 0.773. The three models with the best discriminative capacity were those of Levine et al. (AUC 0.773, 95% CI 0.720-0.827), Hernández et al. (AUC 0.762, 95% CI 0.715-0.809) and Rossi et al. (AUC 0.752, 95% CI 0.707-0.797). CONCLUSIONS: Predictive capacity and methodological quality were limited; therefore, we cannot currently recommend the use of any of the models for decision making in clinical practice. TWEETABLE ABSTRACT: Predictive models that predict the risk of cesarean section in labor inductions are currently not applicable.

3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy for victims of sexual abuse with severe post-traumatic stress disorder: an open label pilot study in Brazil

Objective: To conduct Brazil's first clinical trial employing 3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy for post-traumatic stress disorder (PTSD), given its high prevalence resulting from epidemic violence. Methods: Of 60 volunteers, four matched the inclusion & exclusion criteria. Three patients with PTSD secondary to sexual abuse (diagnosed by the Structured Clinical Interview for DSM-IV and the Clinician Administered PTSD Scale for DSMV-4 [CAPS 4]) completed enrollment and treatment, following a standardized Multidisciplinary Association for Psychedelic Studies protocol consisting of 15 weekly therapy sessions: three with orally administered MDMA with concurrent psychotherapy and music, spaced approximately 1 month apart. CAPS-4 scores two months after the final MDMA session were the primary outcome. Results: No serious adverse events occurred. The most frequent adverse events were somatic pains and anguish. CAPS-4 reductions were always greater than 25 points. The final scores were 61, 27, and 8, down from baseline scores of 90, 78, and 72, respectively. All reductions were greater than 30%, which is indicative of clinically significant improvement. Secondary outcomes included lower Beck Depressive Inventory scores and higher Post-Traumatic Growth Inventory and Global Assessment of Functioning scores. Conclusions: Considering the current limitations in safe and efficacious treatments for PTSD and recent studies abroad with larger patient samples, MDMA-assisted psychotherapy could become a viable treatment in Brazil. Clinical trial registration: RBR-6sq4c9

3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy for victims of sexual abuse with severe post-traumatic stress disorder: an open label pilot study in Brazil.

OBJECTIVE: To conduct Brazil's first clinical trial employing 3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy for post-traumatic stress disorder (PTSD), given its high prevalence resulting from epidemic violence. METHODS: Of 60 volunteers, four matched the inclusion & exclusion criteria. Three patients with PTSD secondary to sexual abuse (diagnosed by the Structured Clinical Interview for DSM-IV and the Clinician Administered PTSD Scale for DSMV-4 [CAPS 4]) completed enrollment and treatment, following a standardized Multidisciplinary Association for Psychedelic Studies protocol consisting of 15 weekly therapy sessions: three with orally administered MDMA with concurrent psychotherapy and music, spaced approximately 1 month apart. CAPS-4 scores two months after the final MDMA session were the primary outcome. RESULTS: No serious adverse events occurred. The most frequent adverse events were somatic pains and anguish. CAPS-4 reductions were always greater than 25 points. The final scores were 61, 27, and 8, down from baseline scores of 90, 78, and 72, respectively. All reductions were greater than 30%, which is indicative of clinically significant improvement. Secondary outcomes included lower Beck Depressive Inventory scores and higher Post-Traumatic Growth Inventory and Global Assessment of Functioning scores. CONCLUSIONS: Considering the current limitations in safe and efficacious treatments for PTSD and recent studies abroad with larger patient samples, MDMA-assisted psychotherapy could become a viable treatment in Brazil. CLINICAL TRIAL REGISTRATION: RBR-6sq4c9.

[Perception of medical communication skills during the clinical interview in a Peruvian teaching hospital: validation and application of an assessment tool]. / Percepción de la competencia comunicativa médica durante la entrevista clínica en un hospital docente peruano: validación y aplicación de un instrumento evaluativo.

OBJECTIVE: To determine the perception of patients regarding physicians communication skills at the outpatient clinic of a teaching hospital in Lima-Peru, using the Communication Assessment Tool (CAT). METHODS: The study population was the group of patients treated in the outpatient clinics of the Cayetano Heredia Hospital. The CAT questionnaire contains 15 questions, and a version validated for Spanish was used. The perception of communication skills was defined as the sum of the scores of all the items, over the number of items, defined as: poor (1), fair (2), good (3), very good, (4), and excellent (5). RESULTS: The percentage of patients who rated communication skills as "poor" (average CAT Score) was 6.8%, "fair" 27.2%, "good" 23.9%, "very good" 30.1 and "excellent" 12.1%. Statistically significant differences were found when comparing the age ranges and among the different levels of education. The group of patients between 18 and 29 years old gave higher scores in the instrument (range 2.2 to 4.87, p = 0.001). Furthermore, when the educational level of the respondent was high, the participants tended to rate physicians with higher scores (range 3.67 to 4.73, p = 0.001). CONCLUSION: We found that 66.2% of patients had a positive perception of the physicians communication skills; only 12.1% rated it as "excellent," a value well below what is reported in the literature. Those who gave the best rating were younger patients with the highest level of education.

OBJETIVO: Determinar la percepción de los pacientes sobre la destreza en la comunicación de los médicos que atienden en consultorio externo de un hospital docente de Lima, Perú, según el instrumento Communication Assessment Tool. MÉTODOS: La población de estudio fue el colectivo de pacientes atendidos en los consultorios externos del Hospital Cayetano Heredia. El cuestionario Communication Assessment Tool consta de 15 preguntas, se utilizó una versión validada al castellano. La percepción de la destreza en comunicación se determinó como la sumatoria de los puntajes del total de las premisas, entre la cantidad de las premisas. Se definió como mala (1), justa (2), buena (3), muy buena (4) y excelente (5). RESULTADOS: El porcentaje de pacientes que calificaron la competencia comunicativa como “mala” (puntaje Communication Assessment Tool promedio) fue de 6,8%, “justa” 27,2%, “buena” 23,9%, “muy buena” 30,1% y “excelente” 12,1%. Se hallaron diferencias estadísticamente significativas respecto a los rangos de edad y entre los distintos grados de instrucción. El grupo de pacientes entre 18 y 29 años otorgó puntajes más altos en el Communication Assessment Tool (rango = 2,2 a 4,87; p = 0,001). Además, cuando el nivel educativo del encuestado fue superior tendió a colocar puntajes más altos (rango = 3,67 a 4,73; p = 0,001). CONCLUSIONES: Se determinó que 66,2% de los pacientes tuvo una percepción positiva, sólo 12,11% lo calificó como “excelente”, un valor muy por debajo a lo reportado en la literatura. Los que brindaron mejor calificación fueron los pacientes jóvenes y con mayor grado de instrucción.

Predictors of mortality and heart transplantation in patients with Chagas' cardiomyopathy and ventricular tachycardia treated with implantable cardioverter-defibrillators.

AIMS: Data on long-term follow-up of patients with Chagas' heart disease (ChHD) receiving a secondary prevention implantable cardioverter-defibrillator (ICD) are limited and its benefit is controversial. The aim of this study was to evaluate the long-term outcomes of ChHD patients who received a secondary prevention ICD. METHODS AND RESULTS: We assessed the outcomes of consecutive ChHD patients referred to our Institution from 2006 to 2014 for a secondary prevention ICD [89 patients; 58 men; mean age 56 ± 11 years; left ventricular ejection fraction (LVEF), 42 ± 12%]. The primary outcome included a composite of death from any cause or heart transplantation. After a mean follow-up of 59 ± 27 months, the primary outcome occurred in 23 patients (5.3% per year). Multivariate analysis showed that LVEF < 35% [hazard ratio (HR) 4.64; P < 0.01] and age ≥ 65 years (HR 3.19; P < 0.01) were independent predictors of the primary outcome. Using these two risk factors, a risk score was developed, and lower- (no risk factors), intermediate- (one risk factor), and higher-risk (two risk factors) groups were recognized with an annual rate of primary outcome of 1.4%, 7.4%, and 20.4%, respectively. A high burden of appropriate ICD therapies (16% per year) and electrical storms were documented, however, ICD interventions did not impact on the primary outcome. CONCLUSION: Among ChHD patients receiving a secondary prevention ICD, older age (≥65 years) and left ventricular dysfunction (LVEF < 35%) portend a poor outcome and were associated with increased risk of death or heart transplantation. Most patients received appropriate ICD therapies, however, ICD interventions did not impact on the primary outcome.

Is It Conceivable to Still Perform the Cut and Sew Cox Maze III Procedure in the Current Era?

To determine whether cut and sew Cox maze III procedure is still associated with adequate safety endpoints when performed in conjunction with other open-heart procedures. Between January 2008 and January 2015, 113 consecutive adult patients were submitted to cut and sew Cox maze III procedure in association with other operations for structural heart disease. Mean age was 49 years and 80 (70.8%) were females. Longstanding or persistent atrial fibrillation has occurred in 87.6% and rheumatic heart disease in 80.7%. Valve surgery was performed in 98.2%. The number of associated procedures was correlated with morbidity and hospital mortality. Overall mean cardiopulmonary bypass and aortic cross-clamping times were 129 ±â€¯26 and 105 ±â€¯23 minutes, respectively. Hospital mortality was 1.77%, re-exploration for bleeding 0.9%, cerebrovascular accident 1.8%, and acute renal failure requiring hemodialysis 2.6%. The greater number of associated procedures did not correlate with poorer safety outcomes. Permanent pacemaker was required in 18.2% of those with three associated procedures, as opposed to 4% with two procedures and no requirement with one procedure (P = .01). Frequency of sinus rhythm was 88%, 88%, and 85% at 6, 12, and 24 months, respectively. In a contemporary single-center cohort of predominantly rheumatic patients, the surgical treatment of atrial fibrillation associated with structural heart disease by means of cut and sew Cox maze III procedure is safe, with low morbidity and mortality rates. Surgical complexity, defined by number of associated procedures, did not translate into poorer safety endpoints, except for greater need of permanent pacemaker.

Transvenous dual-chamber pacemaker after paediatric heart transplantation using left ventricle pacing through the coronary sinus.

A 12-year-old child with end-stage heart failure due to restrictive cardiomyopathy was submitted to orthotopic heart transplantation. Primary graft dysfunction required venous arterial extra-corporeal membrane oxygenation. Heart function normalized, but complete atrioventricular block remained after 3 weeks. A dual-chamber pacing with transvenous left ventricle pacing through the coronary sinus was performed. At 5-year follow-up, the patient is stable with the same pacing system and with preserved ventricular function.

Evaluation of microencapsulation of the UFV-AREG1 bacteriophage in alginate-Ca microcapsules using microfluidic devices.

The indiscriminate use of antibiotics and the emergence of resistant microorganisms have become a major challenge for the food industry. The purpose of this work was to microencapsulate the bacteriophage UFV-AREG1 in a calcium alginate matrix using microfluidic devices and to study the viability and efficiency of retention. The microcapsules were added to gel of propylene glycol for use as an antimicrobial in the food industry. The technique showed the number of the phage encapsulation, yielding drops with an average 100-250µm of diameter, 82.1±2% retention efficiency and stability in the gel matrix for 21days. The gel added to the microencapsulated phage showed efficiency (not detectable on the surface) in reducing bacterial contamination on the surface at a similar level to antimicrobial chemicals (alcohol 70%). Therefore, it was possible to microencapsulate bacteriophages in alginate-Ca and apply the microcapsules in gels for use as sanitizers in the food industry.

Bioimprinting as a tool for the detection of aflatoxin B1 using a capacitive biosensor.

A strategy for the detection of aflatoxin B1 using a capacitive biosensor has been studied. The use of proteins for the generation of sites with high specificity against aflatoxin B1 are produced via bioimprinting. This technique has become a tool for the detection of aflatoxin B1 using a capacitive biosensor. The results demonstrate the ability to generate specific interactions with aflatoxin B1 with a linear relation between signals registered and log concentration of the target aflatoxin in the concentration range of 3.2 × 10-6 to 3.2 × 10-9 M when using ovalbumin as framework for the bioimprinting.

Screening of self-assembled monolayer for aflatoxin B1 detection using immune-capacitive sensor.

A capacitive biosensor was used for detection of aflatoxin B1. Two different methods for cleaning gold electrodes were evaluated using cyclic voltammetry in the presence of ferricyanide as redox couple. The methods involve use of a sequence of cleaning steps avoiding the use of Piranha solution and plasma cleaner. Anti-aflatoxin B1 was immobilized on self-assembled monolayers (SAM). The immune-capacitive biosensor is able to detect aflatoxin B1 concentrations in a linear range of 3.2 × 10-12 M to 3.2 × 10-9 M when thiourea was used to form the SAM; 3.2 × 10-9 M to 3.2 × 10-7 M when thioctic acid was used. When the gold surface was isolated with tyramine-electropolymerization linear ranges of 3.2 × 10-13 M to 3.2 × 10-7 M and 3.2 × 10-9 M to 3.2 × 10-7 M where obtained, respectively. The results obtained show the difference in linear range, limit of detection, and limit of quantification when different self-assembled monolayers are used for aflatoxin B1 detection.

Microemulsification: an approach for analytical determinations.

We address a novel method for analytical determinations that combines simplicity, rapidity, low consumption of chemicals, and portability with high analytical performance taking into account parameters such as precision, linearity, robustness, and accuracy. This approach relies on the effect of the analyte content over the Gibbs free energy of dispersions, affecting the thermodynamic stabilization of emulsions or Winsor systems to form microemulsions (MEs). Such phenomenon was expressed by the minimum volume fraction of amphiphile required to form microemulsion (Φ(ME)), which was the analytical signal of the method. Thus, the measurements can be taken by visually monitoring the transition of the dispersions from cloudy to transparent during the microemulsification, like a titration. It bypasses the employment of electric energy. The performed studies were: phase behavior, droplet dimension by dynamic light scattering, analytical curve, and robustness tests. The reliability of the method was evaluated by determining water in ethanol fuels and monoethylene glycol in complex samples of liquefied natural gas. The dispersions were composed of water-chlorobenzene (water analysis) and water-oleic acid (monoethylene glycol analysis) with ethanol as the hydrotrope phase. The mean hydrodynamic diameter values for the nanostructures in the droplet-based water-chlorobenzene MEs were in the range of 1 to 11 nm. The procedures of microemulsification were conducted by adding ethanol to water-oleic acid (W-O) mixtures with the aid of micropipette and shaking. The Φ(ME) measurements were performed in a thermostatic water bath at 23 °C by direct observation that is based on the visual analyses of the media. The experiments to determine water demonstrated that the analytical performance depends on the composition of ME. It shows flexibility in the developed method. The linear range was fairly broad with limits of linearity up to 70.00% water in ethanol. For monoethylene glycol in water, in turn, the linear range was observed throughout the volume fraction of analyte. The best limits of detection were 0.32% v/v water to ethanol and 0.30% v/v monoethylene glycol to water. Furthermore, the accuracy was highly satisfactory. The natural gas samples provided by the Petrobras exhibited color, particulate material, high ionic strength, and diverse compounds as metals, carboxylic acids, and anions. These samples had a conductivity of up to 2630 µS cm(-1); the conductivity of pure monoethylene glycol was only 0.30 µS cm(-1). Despite such downsides, the method allowed accurate measures bypassing steps such as extraction, preconcentration, and dilution of the sample. In addition, the levels of robustness were promising. This parameter was evaluated by investigating the effect of (i) deviations in volumetric preparation of the dispersions and (ii) changes in temperature over the analyte contents recorded by the method.

Implantable cardioverter-defibrillators for treatment of sustained ventricular arrhythmias in patients with Chagas' heart disease: comparison with a control group treated with amiodarone alone.

AIMS: Evidence is inconclusive concerning the benefit of implantable cardioverter-defibrillators (ICDs) for secondary prevention of mortality in patients with Chagas' heart disease (ChHD). The aim of this study was to compare the outcomes of ChHD patients with life-threatening ventricular arrhythmias (VAs), who were treated either with ICD implantation plus amiodarone or with amiodarone alone. METHODS AND RESULTS: The ICD group [76 patients; 48 men; age, 57 ± 11 years; left ventricular ejection fraction (LVEF), 39 ± 12%] and the historical control group treated with amiodarone alone (28 patients; 18 men; age, 54 ± 10 years; LVEF, 41 ± 10%) had comparable baseline characteristics, except for a higher use of beta-blockers in the ICD group (P < 0.0001). Amiodarone was also used in 90% of the ICD group. Therapy with ICD plus amiodarone resulted in a 72% reduced risk of all-cause mortality (P = 0.007) and a 95% reduced risk of sudden death (P = 0.006) compared with amiodarone-only therapy. The survival benefit of ICD was greatest in patients with LVEF < 40% (P = 0.01) and was not significant in those with LVEF ≥ 40% (P = 0.15). Appropriate ICD therapies occurred in 72% of patients and the rates of interventions were similar across patients with LVEF < 40% and ≥40%. CONCLUSION: Compared with amiodarone-only therapy, ICD implantation plus amiodarone reduced the risk of all-cause mortality and sudden death in ChHD patients with life-threatening VAs. Patients with LVEF < 40% derived significantly more survival benefit from ICD therapy. The majority of ICD-treated patients received appropriate therapies regardless of the LV systolic function.

Antimicrobial effects of silver nanoparticles against bacterial cells adhered to stainless steel surfaces.

Given the increasing number of antibiotic-resistant bacteria and the need to synthesize new antimicrobials, silver has attracted interest in the scientific community because of its recognized antimicrobial activity. This study aimed to evaluate the antimicrobial effects of silver nanoparticles (NP) obtained by a new method and tested at concentrations of 6 µg/ml and 60 µg/ml against the species Staphylococcus aureus, Listeria innocua, Salmonella Choleraesuis, Pseudomonas aeruginosa, Escherichia coli, and Bacillus cereus. The ability of these nanoparticles to remove or kill vegetative cells adhered to stainless steel surfaces was also evaluated. We observed that the NP obtained with the new method, concentrated silver nanoparticles (CNP), and silver nanoparticles with added sodium chloride (NPNaCl) had high antimicrobial activities (P < 0.05). We also verified that the most effective condition for the removal of P. aeruginosa cells on stainless steel coupons (10 by 10 mm) was immersion of the surfaces in CNP. The CNP treatment produced a 5-log reduction of the microbial population after 30 to 60 min of immersion. The CNP treatment also performed better than water and sodium carbonate, a compound commonly applied in clean-in-place procedures in the food industry, in removing adherent B. cereus cells from stainless steel cylinders. Therefore, these results suggest that NP synthesized by a new procedure may be used as antimicrobials in the food industry, for example, for the sanitization of utensils that come into contact with foods.

Thermodynamic study of colorimetric transitions in polydiacetylene vesicles induced by the solvent effect.

We report the synthesis of 10,12-pentacosadyinoic acid (PCDA) and PCDA + cholesterol (CHO) + sphingomyelin (SPH) vesicles dispersed in water and the determination of their colorimetric response induced by small amount of organic solvents. In the absence of solvent, PCDA and PCDA/CHO/SPH vesicles showed an intense blue color. The addition of CHCl(3), CH(2)Cl(2), and CCl(4) caused a colorimetric transition (CT) in both structures with the following efficiency: CHCl(3) > CH(2)Cl(2) ≅ CCl(4). However, CH(3)OH did not cause a blue-to-red transition. By microcalorimetric technique we also determined, for the first time, the enthalpy change associated with the CT process and the energy of interaction between solvent molecules and vesicle self-assembly. We observed that the chloride solvents induced a colorimetric transition, but the thermodynamic mechanism was different for each of them. CT induced by CHCl(3) was enthalpically driven, while that caused by CH(2)Cl(2) or CCl(4) was entropically driven.

Recurrent ventricular arrhythmia after coronary artery bypass grafting treated with radiofrequency catheter ablation.

A 63-year-old diabetic woman was emergently submitted to coronary artery bypass grafting in the setting of acute myocardial infarction. Recurrent, drug-refractory episodes of ventricular arrhythmia occurred for 2 weeks postoperatively, despite no documentation of ongoing myocardial ischemia and optimum medical treatment. Ventricular arrhythmia was initiated by premature ventricular contractions originating from the Purkinje system within the infarct border zone. Radiofrequency catheter ablation was performed at sites where Purkinje potentials were recorded, leading to arrhythmia cessation. A week later, an implantable cardioverter defibrillator was inserted and she was discharged home a few days later. At 15-month follow-up, there were no further episodes of arrhythmia and ventricular function had improved.

Efficacy and safety of circumferential pulmonary vein isolation using a novel cryothermal balloon ablation system.

OBJECTIVES: We sought to evaluate the efficacy and safety of a novel cryothermal balloon ablation system in creating pulmonary vein (PV) isolation. BACKGROUND: Pulmonary vein isolation using standard radiofrequency ablation techniques is limited by procedure-related complications, such as thrombus formation and PV stenosis. Cryothermal ablation may reduce the risk of such complications. METHODS: Eight dogs underwent circumferential ablation of both superior PVs for either 4 or 8 min using a cryothermal balloon catheter (CryoCath Technologies Inc., Kirkland, Canada). Both fluoroscopy and intracardiac ultrasound (ICE)-guided balloon and Lasso catheter positioning at the PV ostia assessed short-term PV integrity. In six additional dogs, long-term PV integrity was assessed by computed tomography at 16 weeks after ablation. RESULTS: Successful electrical isolation was achieved acutely in 14 of 16 (87.5%) PVs and was confirmed in one-week survival studies in 10 of 12 (83%) PVs. Successful isolation was higher in the absence of any peri-balloon flow leak as seen by ICE (p = 0.015), and with balloon temperatures < or =-80 degrees C (p = 0.015). Cryolesions were located at the veno-atrial junction and were homogeneous, with intact endothelium and free of thrombus formation. Although limited angiographic PV narrowing was noted in the early follow-up period, no significant PV narrowing was seen long-term. Right phrenic nerve injury was seen in 50% of the animals studied at one week. CONCLUSIONS: This novel cryothermal balloon ablation system is effective for isolating PVs, but injury to the right phrenic nerve was noted in this early experience. Further studies are needed to assess the long-term efficacy and safety of this technique.

Mechanisms of phrenic nerve injury during radiofrequency ablation at the pulmonary vein orifice.

BACKGROUND: The phrenic nerve can be injured with radiofrequency energy delivery. Nevertheless, the mechanisms of injury are unknown. This study was undertaken to examine phrenic nerve tissue temperatures during ablation at the pulmonary vein (PV) orifice, assess the temperature dependence of injury, and to delineate the possible mechanisms of untoward nerve effects. METHODS: Ten dogs underwent ablation at the right superior PV (RSPV) orifice. Phrenic nerve temperatures were assessed with implanted thermocouples overlying the endocardial ablation site. Using an 8-mm ablation catheter tip, energy was titrated to 50 degrees C and incremented by 5 degrees C for 120 seconds. RESULTS: Phrenic nerve capture was achieved in nine (90%) dogs after thermocouple implantation. A RSPV orifice tissue temperature >60 degrees C occurred in 32 (84%) of energy deliveries with a power of 34 +/- 22 W. In three (33%) dogs, this resulted in nerve dysfunction (maximum nerve temperature: 41 degrees C, 41 degrees C, and 91 degrees C) with histology consistent with acute thermal injury. In four additional dogs, 17 energy deliveries were made directly to the phrenic nerve using a novel in situ model. In 5 (29%) energy deliveries, nerve function was impacted immediately by the generated current, with resolution simultaneous with discontinuing radiofrequency. Transient phrenic nerve injury occurred in all dogs at a temperature of 47 +/- 3 degrees C (range: 43-53 degrees C) after 38 +/- 32 seconds (range: 20-120 seconds). After termination of the energy delivery, nerve function returned in 15(88%) during 30 seconds of postablation pacing. In two (12%) ablation attempts, nerve recovery was delayed (>3 minutes). Permanent injury occurred in all dogs after 92 +/- 83 seconds (range: 20-280 seconds) of additional energy delivery at a temperature of 51 +/- 6 degrees C (range: 45-65 degrees C). CONCLUSION: Phrenic nerve injury can be more common than anticipated with RF ablation at the RSPV orifice. Relatively low tissue temperatures can injure the nerve. Immediate nerve effects suggest a second mechanism of nerve dysfunction related to electrical current. Transient nerve effects occur prior to permanent damage, providing an opportunity to discontinue energy delivery before permanent injury.