Intraoperative Cryoablation Research Articles

Genotype, phenotype and outcomes of patients with hypertrophic cardiomyopathy referred for ablation of ventricular tachycardia

Abstract Background Sustained monomorphic ventricular tachycardia (SMVT) is the most common ventricular arrhythmia (VA) subtype in patients with hypertrophic cardiomyopathy (HCM) who have received an implantable cardioverter defibrillator (ICD). However, data on catheter ablation (CA) are limited and available series typically report results of non-genotyped patients with relatively mild hypertrophy and/or apical aneurysms. Purpose This study describes genotype, phenotype and outcome of consecutive HCM patients referred for CA ablation of refractory SMVT. Methods and results Nine out of 787 patients referred for catheter ablation of SMVT between 01/2016 – 10/2023 had a HCM phenotype, 8/9 with dominant septal hypertrophy, none with LV outflow tract obstruction, and only 1/9 with an apical aneurysm. The median maximal wall thickness was 25 mm (IQR 20,2 – 26,9 mm) and the median left ventricular ejection fraction 34 % (IQR 26-42%). Six patients had a class IV/V variant in the myosine binding protein C (MYBPC3) gene, in 3 no disease-causing variant was identified. All patients with MYBPC3 mutation presented with an electrical storm/incessant VT refractory to antiarrhythmic drugs (AAD), including amiodarone (6/6) and amiodarone + class I AAD (3/6). In an attempt to control VT, 4/6 patients with a MYBPC3 variant required ≥2 ablation including bail out strategies (transcoronary alcohol-ablation, bipolar ablation, half-saline), surgical substrate resection and intraoperative cryoablation (3/6) and radiotherapy (2/6). After a median follow-up of 25 months (IQR 2-75) after the last intervention, all patients with MYBPC3-variants had VT recurrence, 3/6 died and 1/6 underwent heart transplantation. In contrast, patients without class IV/V variants, did not require bail-out strategies; VT recurred in one (single episode) and one patient died, 24 months after CA. The time course of the disease, management and outcome for patients with and without disease causing mutation is illustrated, with the first ablation as center line (figure). Conclusions Only 1 % of patients referred for CA of SMVT to a high-volume center had a HCM phenotype. A MYBPC3 variant was identified in 67%, and, in contrast to prior reports, 89% had severe hypertrophy. VT free survival appears to be particularly poor in MYBPC3 variant carriers despite availability of all treatment modalities. In these patients, early screening for advanced heart failure management including heart transplantation is important.

Impact of cryoablation on operative outcomes in thoracotomy patients.

Cryoablation is increasingly being utilized as an alternative to epidurals for patients undergoing thoracotomies. Current evidence suggests cryoablation may decrease postoperative analgesia utilization, but could increase operative times. We hypothesized that the adoption of intraoperative cryoablation to manage post-thoracotomy pain would result in reduced length of stay and reduced perioperative analgesia compared to routine epidural use. A retrospective analysis was performed from a single, quaternary referral centre, prospective database on patients receiving thoracotomies between January 2020 and March 2022. Patients undergoing transthoracic hiatal hernia repair, lung resection or double-lung transplant were divided between epidural and cryoablation cohorts. Primary outcomes were length of stay, intraoperative procedure time, crossover pain management and oral narcotic usage the day before discharge. During the study period, 186 patients underwent a transthoracic hiatal hernia repair, lung resection or double-lung transplant with 94 receiving a preoperative epidural and 92 undergoing cryoablation. Subgroup analysis demonstrated no significant differences in demographics, operative length, length of stay or perioperative narcotic use. Notably, over a third of patients in each cryoablation subgroup received a postoperative epidural (45.5% transthoracic hiatal hernia repair, 38.5% lung resection and 45.0% double-lung transplant) for further pain management during their admission. Cryoablation use was not associated with an increase in procedure time, a decrease in narcotic use or length of stay. Surprisingly, many cryoablation patients received epidurals in the postoperative period for further pain control. Additional analysis is needed to fully understand the benefits and costs of epidural versus cryoablation strategies.

Intercostal Cryoablation During Video-Assisted Lung Resection Can Decrease Postoperative Opioid Use.

Pain requiring opioid use remains an issue even with minimally invasive thoracic surgery. The objective of this study was to investigate the effectiveness of intercostal nerve cryoablation (CRYO) for pain control in adult patients undergoing pulmonary resection. A retrospective analysis of patients undergoing pulmonary resection by uniportal video-assisted thoracic (uVATS) approach was undertaken. Patients treated with our usual pain regimen (STANDARD) were compared with those who additionally received CRYO. STANDARD includes intercostal bupivacaine, patient-controlled analgesia (24 h), ketorolac (48 to 72 h), and tramadol. Intraoperative CRYO was performed on 5 intercostal levels. The primary aim was to compare pain scores (range, 0 to 10) and morphine equivalent dosages (MED). Secondary outcomes included length of stay, chest tube duration, presence of an air leak, and adverse events. A p value <0.05 was considered significant. There were 49 patients (34 female, 15 male). The median age was 74 (37 to 90) years. Procedures included lobectomy (n = 32), segmentectomy (n = 7), and wedge resections (n = 10). There were 23 (46.9%) CRYO and 26 (53.1%) STANDARD patients. Baseline characteristics were similar. Mean length of stay (2.9 vs 3.5 days), chest tube duration (2.2 vs 1.8 days), and adverse events (9 of 23 vs 7 of 26) were similar. There were no complications attributable to CRYO. Pain scores were not significantly different on postoperative days (POD) 1 to 4. MED was significantly reduced after CRYO on POD 1 (5 vs 47.24), POD 2 (10.93 vs 25.04), POD 3 (8.13 vs 21.7), and POD 4 (7.08 vs 19.17). CRYO can be performed safely during pulmonary resection and can decrease in-hospital opioid use. The results from this retrospective study will need to be validated in future prospective studies.

Intercostal nerve cryoablation during surgical stabilization of rib fractures decreases post-operative opioid use, ventilation days, and intensive care days

BackgroundIntercostal nerve cryoablation is an adjunctive measure that has demonstrated pain control, decrease in opioid consumption, and decrease in hospital length of stay (LOS) in patients who undergo surgical stabilization of rib fractures (SSRF). MethodsSSRF patients from January 2015 to September 2021 were retrospectively compared. All patients received multimodal pain regimens post-operatively and the independent variable was intraoperative cryoablation. Results241 patients met inclusion criteria. 51 (21%) underwent intra-operative cryoablation during SSRF and 191 (79%) did not. Patients with standard treatment consumed 9.4 more daily MME (p = 0.035), consumed 73 percent more post-operative total MME (p = 0.001), spent 1.55 times as many days in the intensive care unit (p = 0.013), and spent 3.8 times as many days on the ventilator than patients treated with cryoablation, respectively. Overall hospital LOS, operative case time, pulmonary complications, MME at discharge, and numeric pain scores at discharge were no different (all p>0.05). ConclusionIntercostal nerve cryoablation during SSRF is associated with fewer ventilator days, ICU LOS, total post-operative, and daily opioid use without increasing time in the operating room or perioperative pulmonary complications.

PO-05-097 FIRST REPORT OF CRYOABLATION OF NON-PAPILLARY MUSCLE PVCS UNDER DIRECT VISUALIZATION DURING MV REPAIR: INTER-LEAFLET TRIANGLE AND THE AORTO-MITRAL CONTINUITY

Up to 60% of patients with mitral valve prolapse (MVP) have premature ventricular contractions (PVC), usually of papillary muscle (PM) origin. However, one-third of PVCs are of non-PM origin, from areas exposed to annular stress forces. We have previously demonstrated the feasibility of intraoperative cryoablation of PM PVCs under direct visualization during mitral valve (MV) repair. To our knowledge, this is the first report of a similar approach for non-PM PVCs. We present two cases of visually-guided surgical cryoablation of non-PM PVCs at the time of elective MV repair. Both were guided by ECG morphology criteria and hybrid PET/MRI imaging pre-operatively. n/a Case 1 (Figure): 73 year old female with degenerative MVP, severe MR and frequent PVCs (27%). There were two PVC morphologies: the dominant PVC was suggestive of interleaflet triangle (ILT) origin (abrupt V3 transition), and the less frequent PVC was consistent with postero-medial PM origin. Hybrid PET-MRI demonstrated focal uptake of FDG in the LV summit region just under the aortic valve. The patient underwent an uncomplicated MV repair, TV repair and cryoablation of the ILT (open endocardial retrograde approach) and then the posterior PM. Follow up TTE showed normal MV and aortic leaflets function without regurgitation or stenosis. An event monitor at 2 months post-op revealed a PVC burden of 2% (off drugs). Case 2: 76 year old male with degenerative MVP, severe mitral regurgitation (MR) and frequent symptomatic PVCs (24%), suggestive of an aortomitral continuity (AMC) origin. Simultaneous cardiac 18F FDG-PET and MRI with LGE imaging demonstrated focal uptake of FDG in the AMC region, no LGE was detected. The patient underwent an uncomplicated MV repair, TV repair and cryoablation of the AMC. The cryo-application was performed on the atrial side of the mitral annulus with forward pressure to reach the ventricular myocardium. There were no PVCs during post-op monitoring and a 6-month follow-up monitor revealed a PVC burden of 1% (off drugs). Surgical cryoablation of non-PM PVCs under direct visualization at the time of MV surgery, using standard ECG criteria and pre-op Hybrid PET-MRI imaging, is feasible. Further studies are needed to determine the safety and effectiveness of adjunctive PVC cryoablation at the time of MV surgery.

Cryoablation in lung transplantation: Its impact on pain, opioid use, and outcomes

ObjectiveTo assess the effect of intraoperative cryoablation on postoperative patient-reported pain, opioid use, and clinical outcomes in lung transplantation. MethodsWe performed a single-center retrospective cohort study of adult lung transplant recipients from August 2017 to September 2018. We compared outcomes of patients who received intraoperative cryoablation of the intercostal nerves with those who did not. Primary outcomes were postoperative patient-reported pain scores and opioid use. Secondary outcomes included postoperative sedation and agitation levels and perioperative outcomes. Data were abstracted from patients' electronic health records. ResultsOf the 102 patients transplanted, 45 received intraoperative cryoablation (intervention group) and 57 received the standard of care, which did not include intercostal or serratus blocks or immediate postoperative epidural placement (control group). The intervention group had significantly lower median and maximum postoperative pain scores at days 3 and 7 and significantly lower oral opioid use at days 3, 7, and 14 compared with the control group. Chronic opioid use at 3 and 6 months' posttransplant was lower in the intervention group. Differences in perioperative outcomes, including length of mechanical ventilation, sedation and agitation levels, and hospital stay, were not clinically meaningful. Survival at 30 days and 1 year was superior in the intervention compared with the control group. ConclusionsFindings suggest that use of intraoperative cryoablation is an effective approach for treating pain and reducing opioid use in patients who undergo lung transplant, but a randomized study across multiple institutions is needed to confirm these findings.

PO-704-06 CLINICAL PREDICTORS OF INDUCIBLE VENTRICULAR ARRHYTHMIAS AND ABLATION EFFECTIVENESS IN TETRALOGY OF FALLOT PATIENTS UNDERGOING PERCUTANEOUS PULMONARY VALVE REPLACEMENT

Peri-operative electrophysiology study (EPS) in patients with tetralogy of Fallot (TOF) undergoing surgical pulmonary valve replacement (PVR) can predict subsequent ventricular arrhythmias (VAs) and intraoperative cryoablation can reduce post-operative VAs. Percutaneous PVR (PPVR) may cover critical anatomic isthmuses that limit future catheter ablation. The clinical predictors of inducible VAs and effects of catheter ablation in patients undergoing PPVR are not known. Explore the clinical predictors and effect of ablation on inducible VAs in TOF patients undergoing PPVR. Patients >25 yrs with TOF who underwent peri-PPVR EPS were identified. Demographics, cardiac imaging, and procedural characteristics were reviewed. Clinical and procedural characteristics were compared between patients with and without inducible VAs. Catheter ablation was performed in patients with inducible VAs. Sixteen patients were identified of which 7 (44%) had inducible VAs. Implanted valves/stents included Sapien™ (11), Melody™ (3), Alterra™ (2) and Harmony™ (1). Arrhythmias included monomorphic VT (4; 57%) and VF (3; 43%). Predictors of inducibility were infundibular resection at initial repair (p=0.04), severe RV dysfunction (p=0.03), and the presence of slowly conducting anatomic isthmuses (SCAIs) (p=0.02). Having only moderate RV dysfunction was protective (p=0.04). All inducible patients underwent ablation with 4 (56%) remaining inducible and having an ICD placed. Having monomorphic VT was predictive of being non-inducible following ablation (p=0.02). No sustained VAs were detected in follow-up (median 9.4 (5-13 mo)). Predictors of inducible VAs in TOF patients undergoing PPVR include prior infundibular resection, severe RV dysfunction, and SCAIs. Targeting SCAIs with ablation may prevent inducible monomorphic VT though percutaneous valves may cover critical isthmuses.

Preliminary Results of Cryoablation for Surgical Treatment of Arrhythmias in Adults With Congenital Heart Disease.

Background: Arrhythmias in adult congenital heart disease (ACHD) are responsible for the majority of hospital admissions and 20–25% of late deaths. Since need for further cardiac operations is frequent in ACHD, concomitant arrhythmia surgery represents a strategic treatment modality.Material and Methods: A two-center retrospective study was undertaken on cryoablation of supraventricular arrhythmias in 25 conescutive ACHD patients (16/9, M/F, median age 38.5 years, IQR 38–60) operated between 01/2017 and 12/2020. Nineteen (76%) had undergone one or more previous cardiac operations and 8 (32%) one or more trans-catheter ablations. Indications included Fontan conversion in seven patients, septal defect repair in 6, pulmonary valve replacement in 10 and tricuspid surgery in 2. Open-heart cryoablation included: 4 cavotricuspid isthmus ablations, 19 right-sided Maze for atrial tachycardia/flutter, and 2 Cox-Maze III for atrial fibrillation.Results: There were 2 (8%) hospital deaths, unrelated to cryoablation, due to low cardiac output syndrome. There were no intraoperative complications related to cryoablation. Seven (28%) patients required pace-maker implantation due to post-operative atrioventricular block. All patients were discharged on oral antiarrhythmic and anticoagulantion for 6 months. After a median follow-up of 14 months (IQR 7–27) no late mortality was observed. At follow-up, 16/23 (69%) patients are in stable sinus rhythm, 12 without anti-arrhythmic therapy. Two (8.6%) patients had relapse of arrhythmia. Freedom from arrhythmia was 90.9% and cumulative risk of recurrence was 9.6%.Conclusions: Intraoperative cryoablation is safe and effective procedure. Surgical treatment of arrhythmias should always be considered in ACHD, whenever further open-heart repair is needed.

Intraoperative cryoablation in late pulmonary valve replacement for tetralogy of Fallot.

Ventricular tachyarrhythmia (VT) is a major cause of late morbidity and mortality in patients who underwent surgical repair of tetralogy of Fallot. The majority of VTs are monomorphic macro-reentrant VT (MVT) and depend on slow conducting areas of diseased myocardium bordered by unexcitable tissue (anatomical isthmuses). Myocardial fibrosis due to surgical incisions, patch material and valve annuli are typical boundaries of anatomical isthmuses (AI). The conducting myocardium between the pulmonary valve and ventricular septum defect patch is called isthmus 3, and the majority of MVTs originate from this area. During pulmonary valve replacement, there is excellent exposure of isthmus 3. Importantly, after pulmonary valve replacement, the homograft may cover important parts of isthmus 3, which makes percutaneous catheter ablation at a later stage impossible. In all patients who need pulmonary valve replacement late after tetralogy of Fallot repair, preoperative electrophysiology study and electroanatomical mapping can identify patients with inducible MVT or slow conduction carrying high risk of MVT. In these patients, intraoperative cryoablation of isthmus 3 should be performed and bidirectional conduction block across the cryoablation line should be demonstrated by intraoperative differential pacing.

Guidance of Intra-Operative Ventricular Tachycardia Ablation during LVAD Implantation with Pre-operative Cardiac MRI

Introduction Ventricular tachycardia (VT) is common in ischemic cardiomyopathy (ICM). Ablation maybe required to reduce ICD shocks and improve the quality of life. Preoperative VT mapping is an invasive electrophysiologic study prior to the surgery which heart failure patients may not tolerate. Substrate modification is usually done in an open epicardial approach during LVAD implantation. Non-invasive mapping techniques have not been described before. In this case pre-operative cardiac magnetic resonance (CMR) imaging was used to plan VT scar mapping and guide intra-operative cryoablation that was done while performing LVAD implantation. Case Report 69-year-old man with ICM (ejection fraction of 23%) and biventricular cardioverter-defibrillator (ICD). He has history of VT, four ablations, and on mexiletine and amiodarone. He had VT-related syncope terminated with anti-tachycardia pacing (ATP). ICD interrogation showed 15 appropriate shocks and >100 ATP therapies since the device implantation 6 months prior. In hospital he had slow monomorphic VT (slow cycle length 650 msec) with left bundle-branch morphology and superior axis positive in AVR. Milrinone was started for cardiogenic shock (cardiac index of 1.81 L/min/m2). He was not a transplant candidate so he was scheduled for destination therapy LVAD. Before the procedure he had sustained monomorphic VTs refractory to ATP requiring ICD shock. Cardiac MRI showed large chronic infarct with marked remodeling and transmural delayed enhancement in the inferoseptal, inferior, and inferolateral segments at the base a mid-ventricular portions of the left ventricle (LV) extending into the inferior aspect of the apical LV. Six myocardial segments equivalent was involved with transmural infarct. We decided to do an intra-operative VT ablation during LVAD implantation. Intraoperatively the LVAD ring was anchored to the apex with sutures. LV incision was made, and cryoablation of the inferoseptal towards inferolateral wall was performed using Cryo3 cryoICE catheter. Corresponding to the scar on MRI ablation lesions were created and the lesions were overlapping (from 3 to 9 o'clock position). The incision site was also cryoablated with a total of ten cryoablations. Conclusion This is the first case to use cardiac MRI for preoperative VT mapping and did correspond to the lesions seen intra-operatively. This is a novel non-invasive mapping tool for heart failure patients undergoing surgical cryoablation . At 1 month follow up the patient has had 68 episodes of non-sustained VT, and 8 episodes of VT, successfully treated with ATP.

The Modified Fontan Procedure With Use of Extracardiac Conduit in Adults: Analysis of 32 Consecutive Patients

Uncommonly, adults with functionally univentricular hearts are becoming candidates for a Fontan procedure. The purpose of this study was to evaluate the course of patients undergoing the modified Fontan procedure with an extracardiac conduit in recent years. Between January 2003 and December 2013, 32 adult patients (17 female and 15 male) underwent total cavopulmonary connection (TCPC) with extracardiac conduit. The median age at procedure was 24.5 years (interquartile range [IQR] 20 to 33 years). The diagnoses included double-inlet left ventricle (DILV) in 10patients (31.2%), tricuspid atresia in 8 patients (25%), double-outlet right ventricle in 4 patients (12.5%), heterotaxia in 4 patients (12.5%), and mitral atresia in 2 patients (6.2%). Seventy-eight percent of patients had undergone at least one prior palliative procedure; the most common procedures were Blalock-Taussig shunt (16patients), superior cavopulmonary shunt (12 patients), and pulmonary artery banding (6 patients). All patients underwent cardiac catheterization preoperatively. Aortic cross-clamping was necessary in 15 patients for intracardiac procedures. Fenestration was required in 9 patients (28%). Four concomitant intraoperative cryoablation procedures were performed. There was no hospital mortality. One patient (3.1%) died 6 months after undergoing TCPC. Morbidities included prolonged pleural effusion lasting more than 7 days in 20 patients (62.5%), atrial arrhythmias in 4patients (12.5%), and permanent pacemakers in 3 patients (9.3%). The median follow-up time was 33 months (interquartile range [IQR], 10.5 to 50 months). Actuarial survival was 91.83% (95% confidence limits, 71.07 to 97.89) at 1 year and 5 years. Ninety-two percent of patients were in New York Heart Association class I or II atfollow-up. The median postoperative oxygen saturation was 95% (IQR, 93% to 95.5%). Cardiac arrhythmia occurred in 4 patients. Systolic ventricular function improved during follow-up for all patients except 1 patient, who underwent cardiac transplantation 7 months after the TCPC. The modified Fontan procedure with use of an extracardiac conduit can be performed in adults with encouraging early and midterm results. The majority of late survivors had improved quality of life. The incidence of late death, reoperation, arrhythmias, and thromboembolic events was low during follow-up.

Cryoablation during left ventricular assist device implantation reduces postoperative ventricular tachyarrhythmias

The number of patients undergoing implantation of a HeartMate II left ventricular assist device (LVAD; Thoratec Corporation, Pleasanton, Calif) is rising. Ventricular tachyarrhythmia (VA) after placement of the device is common, especially among patients with preoperative VA. We sought to determine whether intraoperative cryoablation in select patients reduces the incidence of postoperative VA. From January 2009 through September 2010, 50 consecutive patients undergoing implantation of the HeartMate II LVAD were examined. Fourteen of these patients had recurrent preoperative VA. Of those patients with recurrent VA, half underwent intraoperative cryoablation (Cryo: n=7) and half did not (NoCryo: n=7). Intraoperatively, patients underwent localized epicardial and endocardial cryoablation via LVAD ventriculotomy. Cryothermal lesions were created to connect scar to fixed anatomic borders in the region of clinical VA. Demographics, risk factors, intraoperative features, and outcomes were analyzed to investigate the feasibility of cryoablation. Thirty-day mortality remained low (n=1, 2%) among all LVAD recipients. There were no differences in risk factors between groups except that preoperative inotropes were less prevalent in Cryo patients (P=.09). Compared with NoCryo, the Cryo group had significantly decreased postoperative resource use and complications (P<.05). Recurrent postoperative VA did not develop in any of the Cryo patients (P=.02). Postoperative VA can be minimized by preoperative risk assessment and intraoperative treatment. Localized cryoablation in select patients offers promising early feasibility when performed during HeartMate II LVAD implantation. Further prospective analysis is required to investigate this novel approach.

Two completely separated arrhythmias in one single heart chamber

A 61-year-old male patient underwent an electrophysiological study and ablation for symptomatic atypical atrial flutter which was most likely related to previous intraoperative cryoablation for treatment of paroxysmal atrial fibrillation during open heart surgery. During the procedure, a tachycardia was induced in the electrically isolated left inferior pulmonary vein (PV). With the routine induction protocol, perimitral flutter was induced, whereas, independently, the PV tachycardia was still maintained. After ablation of the mitral isthmus, no tachycardias were inducible anymore.

Early Reperfusion During Acute Myocardial Infarction Affects Ventricular Tachycardia Characteristics and the Chronic Electroanatomic and Histological Substrate

Reperfusion therapy during acute myocardial infarction results in myocardial salvage and improved ventricular function but may also influence the arrhythmogenic substrate for ventricular tachycardia (VT). This study used electroanatomic mapping and infarct histology to assess the impact of reperfusion on the substrate and on VT characteristics late after acute myocardial infarction. The study population consisted of 36 patients (32 men; age, 63+/-15 years) referred for treatment of VT 13+/-9 years after acute myocardial infarction. Fourteen patients with early reperfusion during acute myocardial infarction were compared with 22 nonreperfused patients. Spontaneous and induced VTs and the characteristics of electroanatomic voltage maps were analyzed. Twenty-seven patients were treated by radiofrequency catheter ablation. Ten patients (6 nonreperfused) were treated by ventricular restoration with intraoperative cryoablation in 9. During surgery, biopsies were obtained from the resected core of the infarct. VT cycle length of spontaneous and induced VTs was shorter in reperfused patients (reperfused, 299+/-52/270+/-58 ms; nonreperfused, 378+/-77/362+/-74 ms; P=0.01). An electroanatomic patchy scar pattern was present in 71% of reperfused and 14% of nonreperfused patients (P=0.004). The proportion of electroanatomic dense scar was smaller in reperfused patients (24+/-18% versus 45+/-21%; P=0.02). Histological assessment in 10 patients revealed thick layers of surviving myocardium in 75% of reperfused but in none of the nonreperfused patients. Scar size and pattern defined by electroanatomic mapping are different between VT patients with and without reperfusion during acute myocardial infarction. Less confluent electroanatomic scars match with thick layers of surviving myocardium on histology. Early reperfusion and less confluent electroanatomic scar are associated with faster VTs.

Intraoperative Cryoablation of Atrial Fibrillation With the Old-Fashioned Cryode Tips: A Simple, Effective, and Inexpensive Method

Nowadays atrial fibrillation is usually treated simultaneously with cardiac procedures, and new cryo-systems have been developed for performing easier and faster intraoperative ablation. However, the old cryode designs can still be useful in surgical practice and represent a more cost-effective method. In this article we present a technique using old-fashioned cryodes for intraoperative treatment of atrial fibrillation and comment on its advantages and limitations.

Surgical Treatment of Atrial Fibrillation With argon-based Cryotechnology

Over the past several years numerous attempts have been made to treat atrial fibrillation surgically. The most effective of all such surgical treatments has been the Maze operation, developed by James Cox in the 1980s. The Maze operation has demonstrated excellent long-term results. The procedure is based on a complex surgical technique, thus is it not easily being reproduced by every surgeon. Different attempts have been made to simplify the original Maze technique. In 1999, the electrophysiologists at the authors' institution outlined a lesion concept for left atrial ablation in the treatment of atrial fibrillation. In 387 patients, the authors used intraoperative radiofrequency ablation to cure AF. The results were comparable to the maze procedure. This concept was very effective but after a time period of 4 years in 1% of patients esophagus perforations occurred. In a quest to identify other energy sources to produce good ablation results with less possible complications, intraoperative cryoablation has been developed. In the following study conducted the authors were able to use a new flexible cryocatheter (Cryocath Surgifrost). Sinus rhythm was achieved in 71% after a 1 year follow-up period with low morbidity and comparable mortality, which was due to the concomitant cardiac pathologies and operative procedures. In conclusion, thus far from this series of patients presented, the authors have demonstrated that cryoablation with Argon-cryotechnology is efficacious and safe.

Intraoperative radiofrequency linear catheter ablation of accessory pathways in children with Ebstein’s anomaly undergoing tricuspid annuloplasty

Ebstein’s anomaly is an uncommon congenital lesion affecting approximately 1% of patients with congenital heart disease. It is characterized by downward displacement of the tricuspid valve with the septal and posterior leaflets of the tricuspid valve adherent to the right ventricular septal wall. Ebstein’s anomaly is often associated with supraventricular tachycardia, with estimates of the arrhythmia incidence in this population as high as 42%.1–5 Wolff-Parkinson-White syndrome has been estimated to affect 5% to 10% of this patient group, and sudden death occurred in ≤20% of older patients and adults.3,6 Accessory pathways are usually located along the annulus of the tricuspid valve. There are 2 standard techniques for the definitive treatment of supraventricular tachycardia in this population (radiofrequency catheter ablation [RFCA] in the catheterization laboratory and either intraoperative cryoablation or direct surgical division of accessory pathways). Results for RFCA in children are, in general, good with an acute RFCA success rate of 81% for all ablation targets, though with a 1-year success rate of 57%.7 Thus, despite encouraging acute results in this group, RFCA was ultimately successful in only slightly more than half of those in whom RFCA was attempted. Cryoablation and surgical division with intraoperative mapping have been used with excellent results, although both approaches are time consuming when on cardiopulmonary bypass.8,9 In this report, we present the results of 2 patients with Ebstein’s anomaly and severe tricuspid regurgitation requiring annuloplasty who underwent intraoperative RFCA without intraoperative mapping, using a new, commercially available linear ablation catheter.

Value of Three-dimensional US for Optimizing Guidance for Ablating Focal Liver Tumors

To determine if three-dimensional ultrasound (3D US), by nature of its ability to simultaneously evaluate structures in three orthogonal planes and to study relationships of devices to tumor(s) and surrounding anatomic structures from any desired orientation, adds significant additional information to real-time 2D US used for placement of devices for ablation of focal liver tumors. Sixteen patients underwent focal ablation of 23 liver tumors during two intraoperative cryoablation (CA) procedures, three intraoperative radiofrequency ablation (RFA) procedures, 11 percutaneous ethanol injections (PEI) procedures, and six percutaneous RFA procedures. After satisfactory placement of the ablative device(s) with 2D US guidance, 3D US was used to reevaluate adequacy to device position. Information added by 3D US and resultant alterations in device deployment were tabulated. 3D US added information in 20 of 22 (91%) procedures and caused the operator to readjust the number or position of ablative devices in 10 of 22 (45%) of procedures. Specifically, 3D US improved visualization and confident localization of devices in 13 of 22 (59%) procedures, detected unacceptable device placement in 10 of 22 (45%), and determined that 2D US had incorrectly predicted device orientation to a tumor in three of 22 (14%). Compared to conventional 2D US, 3D US provides additional relationship information for improved placement and optimal distribution of ablative agents for treatment of focal liver malignancy.