Perioperative Red Blood Cell Transfusion Is Associated With Adverse Cardiovascular Outcomes in Heart Valve Surgery.

BACKGROUND: We examined the relationship between blood transfusion and long-term adverse events to evaluate the clinical impact of red blood cell (RBC) transfusion on patients undergoing cardiac valve surgery. METHODS: From the National Health Insurance Service database, individuals undergoing heart valve surgery were verified, including aortic valve (AV), mitral valve (MV), tricuspid valve (TV), and complex valves (more than 2 valve surgeries). The interested outcomes were incidence of death, ischemic stroke, hemorrhagic stroke, and admission for myocardial infarction during follow-up. Associations between perioperative RBC transfusion and long-term cardiovascular events were analyzed with Cox-proportional hazard model. RESULTS: Perioperative RBC transfusion (±2 days from the day of surgery) was categorized into 0, 1, 2, and >3 units based on the number of packs transfused. From 2003 to 2019, the data of 58,299 individuals were retrieved (51.6% were male and 58% were aged above 60 years). The median follow-up duration was 5.53 years. Of the total cohort, 86.5% received at least 1 transfusion. In multivariable analysis, adverse cardiovascular event risk proportionally increased with transfusion in a dose-dependent manner. The adjusted hazard ratios and 95% confidence intervals of outcomes after the transfusion of 1, 2, and ≥3 units compared to those with no transfusion were as follows: death, 1.53 (1.41-1.66), 1.97 (1.81-2.14), and 3.03 (2.79-3.29); ischemic stroke, 1.27 (1.16-1.39), 1.31 (1.19-1.44), and 1.51 (1.38-1.66); hemorrhagic stroke, 1.38 (1.16-1.66), 1.71 (1.43-2.05), and 2.31 (1.94-2.76); and myocardial infarction 1.35 (1.13-1.62), 1.60 (1.33-1.91), and 1.99 (1.66-2.38), respectively (all P < .01). CONCLUSIONS: In the analysis of the national cohort, perioperative RBC transfusion during heart valve surgery was associated with adverse cardiovascular outcomes correlated with the volume of RBC transfusion.

Compressed Deep Learning to Classify Arrhythmia in an Embedded Wearable Device.

The importance of an embedded wearable device with automatic detection and alarming cannot be overstated, given that 15-30% of patients with atrial fibrillation are reported to be asymptomatic. These asymptomatic patients do not seek medical care, hence traditional diagnostic tools including Holter are not effective for the further prevention of associated stroke or heart failure. This is likely to be more so in the era of COVID-19, in which patients become more reluctant on hospitalization and checkups. However, little literature is available on this important topic. For this reason, this study developed efficient deep learning with model compression, which is designed to use ECG data and classify arrhythmia in an embedded wearable device. ECG-signal data came from Korea University Anam Hospital in Seoul, Korea, with 28,308 unique patients (15,412 normal and 12,896 arrhythmia). Resnets and Mobilenets with model compression (TensorFlow Lite) were applied and compared for the diagnosis of arrhythmia in an embedded wearable device. The weight size of the compressed model registered a remarkable decrease from 743 MB to 76 KB (1/10000), whereas its performance was almost the same as its original counterpart. Resnet and Mobilenet were similar in terms of accuracy, i.e., Resnet-50 Hz (97.3) vs. Mo-bilenet-50 Hz (97.2), Resnet-100 Hz (98.2) vs. Mobilenet-100 Hz (97.9). Here, 50 Hz/100 Hz denotes the down-sampling rate. However, Resnets took more flash memory and longer inference time than did Mobilenets. In conclusion, Mobilenet would be a more efficient model than Resnet to classify arrhythmia in an embedded wearable device.

Atrial fibrillation classification based on convolutional neural networks.

BACKGROUND: The global age-adjusted mortality rate related to atrial fibrillation (AF) registered a rapid growth in the last four decades, i.e., from 0.8 to 1.6 and 0.9 to 1.7 per 100,000 for men and women during 1990-2010, respectively. In this context, this study uses convolutional neural networks for classifying (diagnosing) AF, employing electrocardiogram data in a general hospital. METHODS: Data came from Anam Hospital in Seoul, Korea, with 20,000 unique patients (10,000 normal sinus rhythm and 10,000 AF). 30 convolutional neural networks were applied and compared for the diagnosis of the normal sinus rhythm vs. AF condition: 6 Alex networks with 5 convolutional layers, 3 fully connected layers and the number of kernels changing from 3 to 256; and 24 residual networks with the number of residuals blocks (or kernels) varying from 8 to 2 (or 64 to 2). RESULTS: In terms of the accuracy, the best Alex network was one with 24 initial kernels (i.e., kernels in the first layer), 5,268,818 parameters and the training time of 89 s (0.997), while the best residual network was one with 6 residual blocks, 32 initial kernels, 248,418 parameters and the training time of 253 s (0.999). In general, the performance of the residual network improved as the number of its residual blocks (its depth) increased. CONCLUSION: For AF diagnosis, the residual network might be a good model with higher accuracy and fewer parameters than its Alex-network counterparts.

Current Status of Off-pump Coronary Artery Bypass Grafting in Patients with Multiple Coronary Artery Disease Compared with On-pump Coronary Artery Bypass Grafting: The Korean National Cohort Study.

BACKGROUND: Despite advance in off-pump coronary artery bypass (OPCAB) grafting, there are large debating issues regarding survival benefit between OPCAB and on-pump coronary artery bypass grafting (CABG). The aim of this study is to address appropriateness of OPCAB approach in patients with ischemic heart disease having multiple vessels using South Korea national cohort data. METHODS: To evaluate the safety and efficacy of OPCAB, we accessed all causes of death, late repeat revascularization, hospitalization for cerebrovascular accident (CVA), and new renal replacement therapy in patients who underwent isolated CABG with multiple grafting (≥2 grafts) and who were registered in the Korean Health Insurance Review and Assessment Service Database between April 2011 and September 2014. RESULTS: OPCAB was performed in 4,692 patients and on-pump CABG in 2,999 patients from 82 hospitals in South Korea. On multivariable analysis, on-pump CABG was associated with a significantly higher adjusted risk of overall all-cause death (hazard ratio [HR]: 1.876, 95% confidence interval [CI]: 1.587-2.216, p < 0.001) and initiation of new renal replacement therapy (HR: 1.618, 95% CI: 1.124-2.331, p = 0.009). However, we observed no significant difference in repeat revascularization and hospitalization for CVA between the two groups. In propensity score matching, matched patients (2,940 pairs) showed results similar to multivariable analysis that on-pump CABG was associated with a higher overall mortality and initiation of new renal replacement therapy (p < 0.001). CONCLUSION: In this study, we found that OPCAB was associated with better survival rates and renal preservation compared with on-pump CABG.

Evaluation of the Performance and Safety of a Newly Developed Intravenous Fluid Warmer.

To evaluate the performance and safety of a newly developed blood warmer (ThermoSens), we tested its heating capability under various conditions using isotonic saline and hemolysis analysis with swine blood. The following two in vitro tests were performed: (i) To investigate the performance of the device, the inflow and outflow temperatures were measured at various flow rates (30, 50, and 100 mL/min) using cold (5°C) and room temperature (20°C) isotonic saline (0.9%). Several parameters were measured including the highest temperature of the outlet, the time required to reach the highest temperature, and the temperature of the intravenous line. (ii) To investigate the safety of the device, a hemolysis test was performed using swine blood. We obtained 320 mL of whole blood from swine and refrigerated the blood for 35 days at 3°C. In order to replicate the clinical situation, blood flow by gravity and pressure (300 mm Hg) was used. Before and after the heating test, blood samples were obtained and a comparison was made between these samples. Hemoglobin, hematocrit, lactate dehydrogenase, and plasma hemoglobin were used for red blood cell (RBC) damage analysis. The highest outlet temperatures obtained using flow rates of 30, 50, and 100 mL/min were 39.10 ± 0.59, 39.25 ± 0.69, and 37.63 ± 1.03°C, respectively, with cold saline, and 39.40 ± 0.40, 39.66 ± 0.36, and 39.49 ± 0.49°C, respectively, with room temperature saline. Hemolysis tests showed no significant changes in hemoglobin, hematocrit, lactate dehydrogenase, or plasma hemoglobin (P > 0.05) between before and after heating for both gravity and pressure blood flow. The ThermoSens blood warmer warms isotonic saline effectively, reaching temperatures up to 36°C under various conditions. Hemolysis tests showed no RBC damage. Therefore, the newly developed ThermoSens has good heating performance and is safe for RBC products.

A Meta-Analysis of Renal Function After Adult Cardiac Surgery With Pulsatile Perfusion.

The aim of this meta-analysis was to determine whether pulsatile perfusion during cardiac surgery has a lesser effect on renal dysfunction than nonpulsatile perfusion after cardiac surgery in randomized controlled trials. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were used to identify available articles published before April 25, 2014. Meta-analysis was conducted to determine the effects of pulsatile perfusion on postoperative renal functions, as determined by creatinine clearance (CrCl), serum creatinine (Cr), urinary neutrophil gelatinase-associated lipocalin (NGAL), and the incidences of acute renal insufficiency (ARI) and acute renal failure (ARF). Nine studies involving 674 patients that received pulsatile perfusion and 698 patients that received nonpulsatile perfusion during cardiopulmonary bypass (CPB) were considered in the meta-analysis. Stratified analysis was performed according to effective pulsatility or unclear pulsatility of the pulsatile perfusion method in the presence of heterogeneity. NGAL levels were not significantly different between the pulsatile and nonpulsatile groups. However, patients in the pulsatile group had a significantly higher CrCl and lower Cr levels when the analysis was restricted to studies on effective pulsatile flow (P < 0.00001, respectively). The incidence of ARI was significantly lower in the pulsatile group (P < 0.00001), but incidences of ARF were similar. In conclusion, the meta-analysis suggests that the use of pulsatile flow during CPB results in better postoperative renal function.

Improvement of Transfusion Practice in Cardiothoracic Surgery Through Implementing a Patient Blood Management Program.

Background: In this study, we examined the impact of a patient blood management (PBM) program on red blood cell (RBC) transfusion practices in cardiothoracic surgery. Methods: The PBM program had 3 components: monitoring transfusions through an order communication system checklist, educating the medical team about PBM, and providing feedback to ordering physicians on the appropriateness of transfusion. The retrospective analysis examined changes in the hemoglobin levels triggering transfusion and the proportions of appropriate RBC transfusions before, during, and after PBM implementation. Further analysis was focused on patients undergoing cardiac surgery, with outcomes including 30-day mortality, durations of intensive care unit and hospital stays, and rates of pneumonia, sepsis, and wound complications. Results: The study included 2,802 patients admitted for cardiothoracic surgery. After the implementation of PBM, a significant decrease was observed in the hemoglobin threshold for RBC transfusion. This threshold dropped from 8.7 g/dL before PBM to 8.3 g/dL during the PBM education phase and 8.0 g/dL during the PBM feedback period. Additionally, the proportion of appropriate RBC transfusions increased markedly, from 23.9% before PBM to 34.9% and 58.2% during the education and feedback phases, respectively. Among the 381 patients who underwent cardiac surgery, a significant reduction was noted in the length of hospitalization over time (p<0.001). However, other clinical outcomes displayed no significant differences. Conclusion: PBM implementation effectively reduced the hemoglobin threshold for RBC transfusion and increased the rate of appropriate transfusion in cardiothoracic surgery. Although transfusion practices improved, clinical outcomes were comparable to those observed before PBM implementation.

In vitro effect of clinical propofol concentrations on platelet aggregation.

The inhibitory effect of propofol on platelet aggregation remains unclear, and studies on the subject disagree. Furthermore, although propofol infusions are widely used for general anesthesia and as sedatives for patients in intensive care units, little information is available on its concentration- and time-related effects on platelet aggregation. Here, the authors investigated the in vitro effect of propofol, at concentrations required for sedation and general anesthesia, on platelet aggregation after 1, 2, or 3 h. Blood from healthy volunteers (n = 9) was incubated at propofol plasma concentrations of 0, 2, 4, and 10 µg/mL in a water bath at 37°C. Platelet aggregation was measured using a platelet function analyzer (PFA-100) after 1, 2, or 3 h of incubation. Times to occlude collagen/epinephrine (CEPI) or collagen/adenosine 5'-diphosphate (CADP)-coated membranes (closure times, CTs) were measured. The CEPI and CADP CTs of non-incubated blood were 125.6 ± 19.5 s and 93.0 ± 12.2 s, respectively, and no significant difference in CEPI CTs was observed at propofol plasma concentrations of 0, 2, 4, and 10 µg/mL after incubation for 1, 2, or 3 h. CADP CTs were comparable at propofol concentrations of 0, 2, 4, and 10 µg/mL at each incubation time. These findings suggest that propofol at concentrations required for sedation and general anesthesia has no inhibitory effect on platelet aggregation after 3 h of incubation.

Association Between Hypertension and Incident Infective Endocarditis.

BACKGROUND: This study aimed to evaluate the association of hypertension with incident infective endocarditis (IE) by investigating the incidence of IE according to blood pressure levels using the National Health Insurance Service database. METHODS: The data of 4 080 331 individuals linked to the health screening database in 2009 were retrieved (males, 55.08%; mean age, 47.12±14.13 years). From 2009 to 2018, the risk factors for the first episode of IE were investigated. Hypertension was categorized into normotension, prehypertension, hypertension, and hypertension with medication. The Cox proportional hazard model assessed the effect of blood pressure level during the health screening exam on incident IE. RESULTS: During the 9-year follow-up, 812 (0.02%) participants were diagnosed with IE. The incidence rates of IE in the normotension, prehypertension, hypertension, and hypertension with medication groups were 0.9, 1.4, 2.6, and 6.0 per 100 000 person-years, respectively. Those with prehypertension, hypertension, and hypertension with medication were correlated with an increased risk of IE in a dose-response manner compared with the normotension group (hazard ratio, 1.33 [95% CI, 1.06-1.68]; hazard ratio, 1.98 [1.48-2.66]; hazard ratio, 2.56 [2.02-3.24], respectively, all P<0.001). CONCLUSIONS: In a large national cohort study with an average follow-up of 9 years, increased blood pressure was identified as a risk factor for incident IE in a dose-dependent manner. Hypertension increases the public health care burden by acting as a risk factor for rare infective heart diseases.

A Watch-Type Electrocardiography Is a Reliable Tool for Detecting Paroxysmal Cardiac Arrhythmias.

Background: A substantial proportion of cardiac arrhythmias are paroxysmal in nature, and 12-lead electrocardiography (ECG) and Holter monitoring often fail to detect paroxysmal arrhythmias. We designed and evaluated a watch-type, electrocardiograph-recording, wearable device (w-ECG) to overcome the limitations of 12-lead ECG and Holter monitoring. Methods: We prospectively enrolled 96 patients with symptoms assumed to be related to cardiac arrhythmias. Electrocardiography recording was performed with both the w-ECG and Holter monitoring. Detection of any arrhythmia was the primary outcome endpoint and was compared between the w-ECG and Holter monitoring. Results: Any arrhythmia was detected in 51 (53.1%) and 27 (28.1%) patients by the w-ECG and Holter monitoring, respectively (odds ratio (OR) = 2.9, p < 0.001). The w-ECG was superior to Holter monitoring for the detection of clinically significant arrhythmias (excluding atrial premature contraction, ventricular premature contraction, and non-sustained atrial tachyarrhythmia) (OR = 2.34, p = 0.018). In 27 (28.1%) patients, cardiac arrhythmias were detected only by the w-ECG, with atrial fibrillation being the most frequent case (13 patients). Based on ECGs recorded by using the w-ECG, 17 patients (17.7%) received therapeutic interventions, including radiofrequency catheter ablation. Conclusions: The w-ECG is capable of recording ECGs of good quality, with a discernable P wave and distinguishable QRS morphology. The ability of the w-ECG to detect cardiac arrhythmias was significantly better than that of Holter monitoring, and a significant proportion of patients received therapeutic intervention based on ECGs recorded by the w-ECG.

Analysis of pulsatile and nonpulsatile blood flow effects in different degrees of stenotic vasculature.

Vessel lumens that have been chronically narrowed by atherosclerosis should be increased in flow velocity and intrastenotic area pressure to maintain an equal flow. This might be followed by a decrease in hemodynamic energy, leading to a reduction of tissue perfusion. In this study, we compared hemodynamic energies according to degrees of stenotic vasculature between pulsatile flow and nonpulsatile flow. Cannuale with 25, 50, and 75% diameter stenosis (DS) were located at the outlet cannula. Using the Korea Hybrid ventricular assist device (KH-VAD) (pulsatile pump: group A) and Biopump (nonpulsatile pump: group B), constant flow of 2 L/min was maintained then real-time flow and velocity in the proximal and distal part of the stenotic cannula were measured. The hemodynamic energies of two groups were compared. At 75% DS, proximal energy equivalent pressure (EEP) delivered to the distal end was only 41.9% (group A) and 42.5% (group B). As the percent EEP fell below 10%, pulsatility disappeared from the 50% stenosis in group A. The surplus hemodynamic energy (SHE) of group B at all degrees of stenosis must have been 0, which was also the case of group A at 75% stenosis. This research evaluated the hemodynamic energy on various degrees of DS in both pulsatile and nonpulsatile flow with mock system. Using a pulsatile pump, pulsatility disappeared above 50% DS while hemodynamic energy was maintained. Therefore, our results suggest that pulsatile flow has a better effect than nonpulsatile flow in reserving hemodynamic energy after stenotic lesion.

The effect of fluid viscosity on the hemodynamic energy changes during operation of the pulsatile ventricular assist device.

Blood viscosity during operation of ventricular assist device (VAD) can be changed by various conditions such as anemia. It is known generally that the blood viscosity can affect vascular resistance and lead to change of blood flow. In this study, the effect of fluid viscosity variation on hemodynamic energy was evaluated with a pulsatile blood pump in a mock system. Six solutions were used for experiments, which were composed of water and glycerin and had different viscosities of 2, 2.5, 3, 3.5, 4, and 4.5 cP. The hemodynamic energy at the outlet cannula was measured. Experimental results showed that mean pressure was increased in accordance with the viscosity increase. When the viscosity increased, the mean pressure was also increased. However, the flow was decreased according to the viscosity increase. Energy equivalent pressure value was increased according to the viscosity-induced pressure rise; however, surplus hemodynamic energy value did not show any apparent changing trend. The hemodynamic energy made by the pulsatile VAD was affected by the viscosity of the circulating fluid.

A durability study of a paracorporeal pulsatile electro-mechanical pneumatic biventricular assist device.

In 2002, the paracorporeal pulsatile electro-mechanical pneumatic ventricular assist device (VAD) began to be developed by the Korea Artificial Organ Center at Korea University under a Health & Medical Technology Research and Development program which finished in 2008. In vitro durability testing was conducted on the paracorporeal pulsatile pneumatic VAD to determine device durability and to evaluate device failures. The 1- and 2-year reliability of the paracorporeal pulsatile pneumatic VAD was shown to be 91.2% and 54.9%, respectively, with an 80% confidence level. Failure modes were analyzed using fault tree analysis, with customized software continuously acquiring data during the test period. After this period, 21 in vivo animal tests were done, with 14 cases of left atrium to left ventricle (LV) inflow cannulation (36Fr)/outflow grafting to descending aorta, and seven cases of apex cannulation of LV to descending aorta (12 mm). The longest postoperative day (182 days) in Korea was recently recorded in in vivo animal testing (bovine, 90 kg, male, 3.5-4.0 L/min flow rate, and 55 bpm).

Association between Cumulative Fluid Balance and Outcomes in Acute Respiratory Distress Syndrome Patients Treated with Extracorporeal Membrane Oxygenation.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) has become increasingly accepted as a life-saving procedure for patients with severe acute respiratory distress syndrome (ARDS). This study investigated the relationship between cumulative fluid balance (CFB) and outcomes in adult ARDS patients treated with ECMO. METHODS: We retrospectively analyzed the data of adult ARDS patients who received ECMO between December 2009 and December 2019 at Korea University Anam Hospital. CFB was calculated during the first 7 days after ECMO initiation. The primary endpoint was 28-day mortality. RESULTS: The 74 patients were divided into survivor (n=33) and non-survivor (n=41) groups based on 28-day survival. Non-survivors showed a significantly higher CFB at 1-7 days (p<0.05). Cox multivariable proportional hazard regression revealed a relationship between CFB on day 3 and 28-day mortality (hazard ratio, 3.366; 95% confidence interval, 1.528-7.417; p=0.003). CONCLUSION: In adult ARDS patients treated with ECMO, a higher positive CFB on day 3 was associated with increased 28-day mortality. Based on our findings, we suggest a restrictive fluid strategy in ARDS patients treated with ECMO. CFB may be a useful predictor of survival in ARDS patients treated with ECMO.

Evaluation of the hemodynamics of a tissue-engineered hybrid graft.

We evaluated the hemodynamics of tissue-engineered hybrid graft in vivo. The hybrid expanded polytetrafluoroethylene (ePTFE) scaffold was fabricated by coating the ePTFE graft with poly (lactide-co-glycolide) (PLGA) solution. This scaffold was turned into an engineered hybrid graft by culturing smooth muscle cells on its surface. Both the ePTFE (n = 6) and the engineered hybrid grafts (n = 8) were implanted in the carotid arteries of mongrel dogs. The length of intima in the engineered hybrid graft was greater than the ePTFE. The neoarterial thickness in the engineered hybrid group was greater, and the foreign body reaction was more severe. We compared the hemodynamics (diameter, flow rate, pulsatile index, mean velocity, shear stress, resistance index, and systolic/diastolic ratio) of the native arteries in the distal anastmosis. The shear rate in the engineered hybrid group was higher immediately after implantation, and the resistance index was lower, but there was no significant difference after 4 weeks. The engineered grafts demonstrated similar hemodynamics with the ePTFE grafts after 4 weeks implantation.

Experimental investigation of pulsatility effect on the deformability and hemolysis of blood cells.

In this study, we investigated the differences between pulsatile cardiopulmonary bypass (CPB) procedure and nonpulsatile CPB procedure in terms of their effects on hemolysis and deformability of red blood cells (RBCs) under various shear stress conditions. In order to research the effects on hemolysis and deformability, four parameters--free hemoglobin (fHb) concentration, normalized index of hemolysis (NIH), deformability index (DI) of RBCs, and elongation index of RBCs--have been deeply investigated. For these investigations, two randomly assigned adult mongrel dog groups-nonpulsatile group (NP, n = 6) and pulsatile group (P, n = 6)--were examined. According to our results, both types of perfusion did not show any statistical differences in terms of the concentrations of fHb as well as NIH. In addition, there were no significant differences in RBC deformability between perfusion types within an operation time of 3 h. Therefore, our studies suggest that pulsatile perfusion has no significant difference from nonpulsatile perfusion in terms of hemolysis and deformability of RBCs.

Partial pericardial defect incidentally discovered during coronary bypass surgery.

A 71-yr-old male patient with three vessel coronary artery disease underwent a coronary artery bypass graft. The patient was found to have a large pericardial defect at the apex of the heart that measured approximately 18 cm in circumference. The edge of the pericardial defect impinged on the epicardial coronary arteries. The left phrenic nerve descended via the dorsal boundary of the pericardial defect. Following coronary artery bypass grafting, the pericardial defect was repaired with a polytetrafluorethylene patch. The patient had an uncomplicated postoperative course.

A Giant Pseudo-Aneurysm on the Anastomosis Site for a Redo Bentall Operation due to Behçet Disease Treated by Thoracic Endovascular Aortic Aneurysm Repair with a Custom-Made Stent Graft.

A 34-year-old man who had undergone aortic valve replacement 8 years ago underwent an additional Bentall operation due to mechanical valve dehiscence 2 years later. Subsequently, he was diagnosed with Behçet disease and Batter syndrome. A week after being hospitalized again due to chest pain and dyspnea, a large pseudo-aneurysm was detected on computed tomography. Because of the excessively large size of the pseudo-aneurysm, surgical treatment seemed very risky. Therefore, we planned to perform thoracic endovascular aortic repair (TEVAR) and treated him successfully. However, the patient experienced recurrence of the same symptoms 4 months later, and was found to have type IV endoleak. He received a TEVAR procedure again, and it was successful.

Management of Atrio-esophageal Fistula Induced by Radiofrequency Catheter Ablation in Atrial Fibrillation Patients: a Case Series.

Atrio-esophageal fistula (AEF) is one of the most devastating complication of radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) and surgical repair is strongly recommended. However, optimal surgical approach remains to be elucidated. We retrospectively reviewed AEF cases that occurred after RFCA in a single center and evaluated the clinical results of different surgical approach. Surgical or endoscopic repair was attempted in five AF patients who underwent RFCA. Atrio-esophageal fistula and mediastinal infection was not controlled in the patient who underwent endoscopic repair eventually died. Lethal cerebral air embolism occurred two days after surgery in a patient who underwent esophageal repair only. Primary surgical repair of both the left atrium (LA) and esophagus was performed in the remaining three patients. Among these three patients, two underwent external LA repair and the remaining had internal LA repair via open-heart surgery. External repair of the LA was unsuccessful and one patient dies and another had to undergo second operation with internal repair of the LA. The patient who underwent internal LA repair during the first operation survived without additional surgery. Furthermore, we applied veno-arterial extracorporeal membrane oxygenation (VA-ECMO) with artificial induction of ventricular fibrillation in this patient to prevent air and septic embolism and she had no neurologic sequelae. In summary, surgical correction can be considered preferentially to correct AEF. Open-heart surgical repair of LA from the internal side seems to be an acceptable surgical method. Application of VA-ECMO with artificial induction of ventricular fibrillation might be effective to prevent air and septic embolism.

Rescue Extracorporeal Bypass to Prevent Atrioesophageal Fistula-related Air Embolism.

Atrioesophageal fistula (AEF) is a rare but disastrous complication encountered after radiofrequency catheter ablation for atrial fibrillation or flutter. Furthermore cerebral air embolism due to AEF is considered a strong predictor of mortality. In our case a patient presented with AEF and cerebral air embolism. As a rescue effort ventricular fibrillation was induced and sustained under venoarterial extracorporeal membrane oxygenation support until emergency AEF repair was feasible. Herein we report the successful use of the above measures to prevent further air embolism in a patient with radiofrequency catheter ablation-related AEF.