Atrial ablation and esophageal injury: comments on an experimental study.
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Animals↗
Biomedical subjects
Fernando Hornero
Publications and source records attributed to Fernando Hornero.
Esophageal temperature during radiofrequency-catheter ablation of left atrium: a three-dimensional computer modeling study.
INTRODUCTION: There is current interest in finding a way to minimize thermal injury in the esophagus during radiofrequency-catheter ablation of the left atrium. Despite the fact that the esophageal temperature is now being monitored during ablation, the influence of different anatomic and technical factors on the temperature rise remains unknown. METHODS AND RESULTS: We implemented a three-dimensional computational model that included atrial tissue, epicardial fat, esophagus, aorta, and lung, all linked by connective tissue. The finite-element method was used to calculate the esophageal temperature distribution during a procedure of constant-temperature ablation with an 8-mm electrode, under different tissue conditions. Results showed that the distance between electrode and esophagus was the most important anatomic factor in predicting the esophageal temperature rise, the composition of the different tissues being of lesser importance. The measurement of the esophageal temperature in different sites of the lumen offered differences up to 3.7 degrees C, especially for a short electrode-esophagus distance (5 mm). The difference in the convective cooling by circulating blood around electrode and endocardium did not show a significant influence on the esophageal temperature rise. CONCLUSION: Computer results suggest that (1) the electrode-esophagus distance is the most important anatomic factor; (2) the incorrect positioning of an esophageal temperature probe could give a low reading for the maximum temperature reached in the esophagus; and (3) the different cooling effect of the circulating blood flow at different atrial sites has little impact on the esophageal temperature rise.
Atrial Fibrillation↗
A cooled intraesophageal balloon to prevent thermal injury during endocardial surgical radiofrequency ablation of the left atrium: a finite element study.
Recent clinical studies on intraoperative monopolar radiofrequency ablation of atrial fibrillation have reported some cases of injury to the esophagus. The aim of this study was to perform computer simulations using three-dimensional finite element models in order to investigate the feasibility of a cooled intraesophageal balloon appropriately placed to prevent injury. The models included atrial tissue and a fragment of esophagus and lung linked by connective tissue. The lesion depth in the esophagus was assessed using a 50 degrees C isotherm and expressed as a percentage of thickness of the esophageal wall. The results are as follows: (1) chilling the esophagus by means of a cooled balloon placed in the lumen minimizes the lesion in the esophageal wall compared to the cases in which no balloon is used (a collapsed esophagus) and with a non-cooled balloon; (2) the temperature of the cooling fluid has a more significant effect on the minimization of the lesion than the rate of cooling (the thermal transfer coefficient for forced convection); and (3) pre-cooling periods previous to RF ablation do not represent a significant improvement. Finally, the results also suggest that the use of a cooled balloon could affect the transmurality of the atrial lesion, especially in the cases where the atrium is of considerable thickness.
Burns↗
What affects esophageal injury during radiofrequency ablation of the left atrium? An engineering study based on finite-element analysis.
Recent studies on intraoperative radiofrequency ablation of atrial fibrillation have reported some cases of injury to the esophagus. The aim of this study was to perform computer simulations using a theoretical model in order to investigate the effect of different factors on the temperature distributions in the esophagus during ablation. A three-dimensional model was built to include an active electrode, atrial tissue, epicardial fat layer and a fragment of esophagus, aorta and lung, all linked by connective tissue. The finite-element method was used to calculate the temperature distribution during a procedure of constant-temperature ablation. The lesion geometry was assessed using a 50 degrees C isotherm. Our results show that the electrical power directly applied to the esophagus is insignificant and hence the esophageal injury is exclusively due to thermal conduction from the atrium. The esophageal lesion is mainly influenced by the thickness of connective tissue. Both the programmed target temperature of the electrode and the duration of the ablation also have a significant effect on the lesion in the esophagus. In contrast, the epicardial fat layer (0.9 mm thickness) did not show a significant influence. In conclusion, this theoretical model allows us to study the effect of different factors on the thermal injury in the esophagus during intraoperative radiofrequency ablation of atrial tissue.
Catheter Ablation↗
True versus false ventricular aneurysm: accurate diagnosis with gadolinium magnetic resonance.
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Aneurysm, False↗
Virtual vascular endoscopy for acute aortic dissection.
Virtual endoscopy of the aorta is a new three-dimensional reconstruction method from multislice computed tomography or magnetic resonance that offers a virtual navigation through the aorta, and the possibility of having a new preoperative endoluminal vision. We present a case of subacute aortic dissection with a preoperative virtual endoscopy of the aorta.
Aged↗
[Trends in coronary artery bypass surgery: changes in the profile of the surgical patient].
INTRODUCTION AND OBJECTIVES: In the last few years, the percentage of high-risk patients proceeding to coronary artery bypass surgery has increased. The most common risk factors are older age and the presence of comorbid complaints. We carried out a retrospective study to confirm this new risk profile and to evaluate its impact on surgical results. PATIENTS AND METHOD: We analyzed the changing risk profile of 1360 patients who underwent coronary artery bypass surgery in our hospital between 1993 and 2001, divided into three historical cohorts: 1993-1996, 1997-1999 and 2000-2001. The main factors associated with morbidity and mortality were analyzed by logistic regression analysis. The introduction of new operative techniques, such as off-pump surgery and arterial grafting, was also evaluated. RESULTS: The patients' risk profile worsened over time: patients were older, comorbid complaints were more common, and ventricular function was poorer. EuroSCORE figures reflected this trend: estimated mortality in the three historical cohorts was 2.0%, 4.0% and 4.2%, respectively (P<.001). However, risk-adjusted mortality, at 3.7%, 2.7% and 1.5%, respectively, decreased (P<.05), and combined overall morbidity and mortality remained stable, at 16.7%, 16.4% and 13.8%, respectively, (P<.39). There was a non-significant tendency for arterial grafting and off-pump surgery to reduce in-hospital morbidity and mortality. CONCLUSIONS: The risk profile of patients undergoing surgery has worsened as their mean age has increased and as comorbid complaints have become more prevalent. However, there has been no simultaneous increase in risk-adjusted mortality. The potential benefits of new surgical advances such as off-pump surgery and multiple arterial grafting must be corroborated by future studies.
Coronary Artery Bypass↗
Thermal-electrical modeling for epicardial atrial radiofrequency ablation.
Epicardial radiofrequency ablation is increasingly being used for intraoperative treatment of atrial fibrillation. However, the effect of different parameters on the lesion characteristics has not been sufficiently characterized. We used a finite element model to calculate the temperature distribution in the atrial tissue under different conditions during a constant voltage radiofrequency ablation. Our simulation results show that although in the case of a thin atrium the lesion was less deep for a thin atrium, it was easier to achieve transmurality. While considering a thinner atrium, the location of the hottest point of the lesion shifted from the electrode tip to epicardial surface. This effect was due to the convective cooling of the circulating blood inside the atrium. This convective cooling phenomenon has almost negligible effects for atria thicker than 3 mm. The variability of the cooling values has no significant effect on the lesion, even for thin atria (1-2 mm). Increasing the electrode insertion depth (ID) in the tissue produced larger lesions. However, for thinner atria (thickness <2 mm), this increase in the ID reduced the lesion width. It was also proved that the presence of a fat layer between the electrode and the atrial tissue decreased significantly the lesion dimensions.
Adipose Tissue↗
Midterm clinical and echocardiographic results with patch glue repair of left ventricular free wall rupture.
BACKGROUND: Left ventricular free wall rupture (LVFWR) is a dramatic complication after myocardial infarction. We present our mid-term clinical and echocardiographic results of LVFWR with an epicardial patch without cardiopulmonary bypass. METHODS: From February 1993 to May 2001, 17 patients underwent surgery for LVFWR. The mean age+/-SD of 12 males and 5 females was 68+/-10 years. All patients presented for emergency surgery with cardiac tamponade confirmed on echocardiography. After opening the chest and identification of the site of rupture, a Goretex patch was fashioned and applied with enbucrilate surgical glue. RESULTS: Effective control of bleeding was achieved in all cases. There were no on-table deaths. The operative (30 day) mortality was 23.5% (4/17). One death occurred because of patch failure, two because of cardiogenic shock, and one from pneumonia. On follow-up at a median of 2.2 years (interquartile range, 1.1 to 4.3 years), two further deaths occurred, one from myocardial infarction and another of undetermined etiology. Echocardiography did not reveal any evidence of restriction to left ventricular free wall motion. CONCLUSIONS: Patch glue repair is expedient, simple and effective; with no adverse effects on mid-term ventricular dynamics. In view of superior published results to infarctectomy and repair with extra corporeal circulation, it should be considered to be the initial procedure of choice for the surgical repair of LVFWR.
Aged↗
[Aortic valve replacement in patients over 70 years old: determinants of early death].
INTRODUCTION AND OBJECTIVES: There is controversy regarding the risk factors associated with early death in geriatric patients undergoing aortic valve replacement. We analyzed the risks in these patients and established an accurate model for predicting in-hospital mortality. PATIENTS AND METHOD: Univariate and multivariate analyses were made of the risk factors associated with early death in a group of 129 patients older than 70 years who underwent aortic valve replacement (May 1994-June 2001). The variables obtained by multivariate logistic regression were combined to produce an equation for the prediction of early death. The equation was tested using a receiver operating characteristic curve. RESULTS: Univariate analysis identified four factors related to early death: NYHA III-IV (p < 0.0001), ejection fraction < 40% (p < 0.05), aortic regurgitation (p < 0.05) and high left ventricular mass index (p < 0.05). Multivariate analysis revealed three independent risk factors: NYHA III-IV (p < 0.01), aortic regurgitation (p < 0.05), and small body surface area (p < 0.05). A lower mortality was observed in patients with a larger body surface area (0% for > 1.90 m2, 20% for < 1.40 m2). The estimated mortality with the predictive model was 7.06%, which was similar to the observed mortality of 7.80% (area under the ROC curve 0.87) and better than estimates obtained with the EuroSCORE (6.5%; area under the ROC curve 0.56). CONCLUSIONS: Risk factors associated with early death after aortic valve replacement in geriatric patients include functional status, aortic regurgitation, and small body surface area. Our model based on these factors accurately predicted operative mortality in our patients. Gender, prosthesis size, and pump time were not identified as risk factors.
Aged↗
[Assessment of coronary by-pass grafts with multislice CT].
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Acute Disease↗
Surgery for left ventricular free wall rupture: patch glue repair without extracorporeal circulation.
Left ventricular free wall rupture is a dramatic complication after myocardial infarction. We present our experience with the simple, expedient technique of patch glue repair without extracorporeal circulation. Access is obtained via median sternotomy. Evacuation of blood and haematoma is undertaken and a Goretex patch exceeding the size of infarct is fashioned. The patch is applied to the epicardium using enbrucrilate surgical glue instilled with gentle pressure against the beating heart. We performed this technique on 17 patients from 1993 to 2001, with a operative (30-day) mortality of 23.5% with a post-discharge survival of 85% at 2.2 years.
Aged↗
Long electrodes for radio frequency ablation: comparative study of surface versus intramural application.
There is increasing use of radio frequency (RF) ablation with long electrodes in the intraoperative treatment of atrial fibrillation. Nevertheless, the disparity in the lesion geometry in both depth and width is the major pitfall in the use of RF currents. The objective of this study was to differentiate the shape and size of long lesions created by three surface application electrodes (SAE) and two intramural electrodes (IE). The SAE included a standard multi-polar catheter, and two standard electrosurgical pencils. The IE consisted of a needle and a wire both intramurally buried. The lesions were created on fresh fragments of porcine ventricular tissue. The IE created lesions with a curved prism-like shape around the electrode body, with homogeneous characteristics along the lesion trajectory. On the contrary, the lesions created with the SAE were in the shape of an hourglass. They showed a different geometry between the central zone and the edge zone (p<0.001 for depth and surface width). Electrical impedance evolution was recorded during the RF heating. We observed a slow decrease of the impedance in all the electrodes, except in the wire electrode. In conclusion, the results suggest that the IE might be a more suitable option than SAE when it is necessary to create long and homogeneous thermal lesions.
Animals↗
[Advantages of off-pump coronary bypass surgery in high-risk patients].
INTRODUCTION AND OBJECTIVES: Myocardial revascularization without cardiopulmonary bypass has been shown to reduce operative morbi-mortality. We report our recent experience with this novel technique in order to evaluate its theoretical advantages in comparison with conventional surgery. PATIENTS AND METHODS: This retrospective analysis included 547 consecutive patients undergoing isolated myocardial revascularization from December 1997 through November 2000. One hundred twenty-one off-pump patients were compared to 426 undergoing cardiopulmonary bypass. Logistic regression analysis was performed to find predictors of mortality, transfusion, postoperative atrial fibrillation and length of hospital stay. RESULTS: Off-pump patients were at greater risk: they were older, with a lower ejection fraction and a higher prevalence of unstable angina, heart failure and associated comorbidity. Off-pump surgery reduced transfusions (1 1 vs 1,9 2 blood units; p < 0.0001) and postoperative hospital stays (8.9 5 vs 11,3 7 days; p < 0.001). The off-pump group showed a trend toward reduced morbidity but the technique did not decrease hospital mortality. Cardiopulmonary bypass was an independent predictor of blood transfusion and longer hospital stay. Short-term follow-up revealed no significant differences in recurring angina or patency rates. CONCLUSIONS: Off-pump coronary bypass surgery is a good option in high-risk patients because it reduces the incidence of perioperative transfusion and the length of hospitalization. Furthermore, it showed a trend toward reduced morbidity. Mortality was not significantly higher in spite of the higher risk of the patients. Long-term longitudinal follow-up is mandatory to assess the true effectiveness of this technique.
Aged↗
Atrial remodeling after mitral valve surgery in patients with permanent atrial fibrillation.
BACKGROUND: Mitral valve pathology is frequently associated with auricular dilatation and atrial fibrillation. Mitral surgery allows an immediate surgical auricular remodeling and besides in those cases in which sinus rhythm is reached, it is followed by a late remodeling. The aim of this study is to investigate the process of postoperative auricular remodeling in patients with permanent atrial fibrillation undergoing mitral surgery. METHODS: In a prospective randomized trial, 50 patients with permanent atrial fibrillation and dilated left atrium, submitted to surgical mitral repair, were divided into two groups: Group I contained 25 patients with left auricular reduction and mitral surgery, and Group II contained 25 patients with isolated valve surgery. Both groups were considered homogeneous in the preoperative assessment. RESULTS: After a mean follow-up of 31 months, 46% of patients included in Group I versus 18% of patients included in Group II restarted sinus rhythm (p = 0.06). An auricular remodeling with size regression occurred in those patients who recovered from sinus rhythm, worthy of remark in Group II (-10.8% of left auricular volume reduction in Group I compared to -21.5% in Group II; p < 0.05). A new atrial enlargement took place in those patients who remained with atrial fibrillation (+16.8% left auricular volume in Group I vs. +8.4% in Group II; p < 0.05). CONCLUSIONS: Mitral surgery produces an atrial postoperative volume that decrease especially when reduction techniques are employed. Late left atrial remodeling depended on the type of atrial rhythm and postoperative surgical volume.
Aged↗
Surgical ablation of permanent atrial fibrillation by means of maze radiofrequency: mid-term results.
BACKGROUND: The maze procedure can be performed surgically with radiofrequency, generating transmural ablation lines. We report our experience with a biatrial pattern of lesions based on the use of epicardial and endocardial radiofrequency ablation in an effort to minimize maze procedure. METHOD: In 85 patients undergoing cardiac surgery for established permanent atrial fibrillation (>3 months), a biauricular pattern of epicardic-endocardic maze lesions was performed. The main surgical procedures were diverse: 42 mitral valve surgeries, 7 mitrotricuspid valves, 18 mitroaortics, 4 mitroaortic and tricuspids, 2 aortic valves, 3 CABGs, 5 CABG and valve procedures, and 4 atrial septal defects. The mean age of the patients was 61 +/- 12 (range 39-78). The mean duration of atrial fibrillation was 5.8 years (range 0.3 to 24). RESULTS: Sixty-two (72.9%) patients presented postoperative supraventricular arrhythmia. Hospital mortality was seen in five patients (5.8%). Two patients died after a 12-month mean follow-up (range 2 to 32). A total of 14.1% of patients remained with their previous atrial fibrillation and 85.9% recovered and maintained sinus rhythm, with two patients having a permanent pacemaker. A total of 56% patients have been followed-up for a period of more than 6 months, and among them prevalence of sinus rhythm is 87.5%. Echocardiography detected biauricular contraction in 65% of them. After analyzing the data, factors involved in postoperative recurrence of atrial fibrillation after radiofrequency surgery were oldness of the atrial fibrillation (p < 0.01) and pre and postoperative left auricle volume (p < 0.04). CONCLUSION: Intraoperative radiofrequency has permitted us to perform the maze procedure in a simple way, with a low surgical morbid-mortality. We have obtained an 85.9% electrographic effectiveness and a 65% recovery of atrial contraction. Postoperative incidence of arrhythmia is the main postoperative problem.
Adult↗