Surgical treatment of atrial fibrillation using argon-based cryoablation during concomitant cardiac procedures

Massive Atrial Thrombosis: A Serious Complication of the Maze Procedure Triggered by Heparin-Induced Thrombocytopenia (HIT)

Atrial fibrillation is one of the most common cardiac arrhythmias, classically presenting with an "irregularly irregular" rhythm with or without chest pain, palpitations, shortness of breath, lightheadedness, or fatigue. The maze procedure is an open-heart operation that creates a carefully designed maze of incisions and ablations in the atrial myocardium. Although it is a common procedure, serious complications may happen. Herein, we report on a 76-year-old man who presented with chest pain and atrial fibrillation and was found to have multi-vessel disease on a coronary angiogram. He underwent coronary artery bypass and the COX-maze procedure, which was complicated by a massive thrombosis in the atria and the superior vena cava following the ablation line, secondary to heparin-induced thrombocytopenia, which is extremely rare. The central focus of this paper is to present this rare complication to stress the importance of rigorous follow-up and anticoagulation therapy in patients undergoing the maze procedure. To our knowledge, we are the first to report such a rare case of diffuse large atrial thrombi triggered by heparin-induced thrombocytopenia (HIT) type II after a COX-maze procedure.

The influence of epicardial and endocardial use of cryoenergy on the completeness of lesions in surgical ablation of atrial fibrillation

Introduction

Cryoenergy is the most commonly used method of lesion formation in patients who have undergone surgical ablation of atrial fibrillation. Despite frequent use, the clinical effect of cryoenergy in endocardial and epicardial approaches is unknown.

Aim

To compare the effect of various cryoenergy applications on the postoperative incidence of sinus rhythm and completeness of lesions performed.

Material and methods

A total of 55 patients underwent concomitant atrial fibrillation surgical ablation using cryoenergy under various conditions: epicardially during cardiac arrest, epicardially on beating heart, and endocardially. In the postoperative period, patients were invited to attend an electrophysiological examination to assess the completeness of surgical ablation lesions and, if necessary, to complete catheter ablation.

Results

Twenty-four patients underwent epicardial ablation on the arrested heart (group 1), 12 patients underwent epicardial ablation on the beating heart (group 2), and 19 patients underwent endocardial ablation (group 3). In the electrophysiological examination, sinus rhythm was present in 71% vs. 83% vs. 89% of patients, respectively. The completeness of pulmonary vein isolation was confirmed in 31% vs. 25% vs. 95% of patients, complete box lesions in 15% vs. 0% vs. 79% of patients, respectively.

Conclusions

Despite the similar clinical effect of surgical ablation in all three approaches, the morphologically most effective use of cryoenergy is endocardial ablation. This approach has a very good result. Our findings further support the endocardial use of cryoenergy during surgical ablation of atrial fibrillation.

Massive Left Atrial Thrombus in Two Patients with Heparin-Induced Thrombocytopenia Type II after Cardiac Surgery

Heparin-induced thrombocytopenia type II (HIT type II) can have devastating consequences in cardiac surgical patients. We report two cases of massive left atrial thrombus after mitral valve replacement and endocardial cryoablation in patients with HIT type II.

Bivalirudin fails to prevent atrial thrombus development in heparin-induced thrombocytopaenia and thrombosis syndrome

An 81-year-old woman presented with acute decompensated heart failure due to new-onset atrial fibrillation and a flail myxomatous mitral valve which necessitated surgical mitral valve repair. No atrial thrombi were noted on transoesophageal echocardiograms performed prior to surgery and intraoperatively. Immediately postoperatively, while treated with unfractionated heparin, the patient developed thrombocytopaenia with positive platelet factor 4 antibodies and an abnormal serotonin functional platelet assay, consistent with heparin-induced thrombocytopaenia. The anticoagulation therapy was changed to the direct thrombin inhibitor bivalirudin with an improvement in the platelet count. Despite bivalirudin therapy, a left atrial layering thrombus was revealed on transoesophageal echocardiogram performed in preparation for cardioversion of the symptomatic atrial fibrillation. Anticoagulation was changed to warfarin, and the patient was discharged without thromboembolic complications neither during her hospital stay nor the 3-year outpatient follow-up.

Application of cryoablation for the treatment of atrial fibrillation in patients undergoing cardiac surgery: Our mid-term results

Background

In this study, we aimed to present mid-term results of concomitant argon-based cryoablation in patients undergoing cardiac surgery.

Methods

Between August 2014 and May 2016, 33 patients (17 males, 16 females; mean age 63.9 years; range 45 to 82 years) underwent the Maze procedure using cryoablation for the treatment of atrial fibrillation during a concomitant open cardiac operation. Robot-assisted procedures were used in 12 patients. Biatrial or isolated left atrial ablation was performed according to the underlying pathology. The rhythm assessment with 12-lead electrocardiography and 24-hour Holter, and recordings of atrial fibrillation-related medications, stroke or other thromboembolic events were evaluated by the cardiologist at 3 and 12 months postoperatively.

Results

Thirty patients (90.9%) were in sinus rhythm and three (9.1%) were in atrial fibrillation at the time of discharge. Cryoablation failed in three patients (n=2, 8.3% in isolated left atrial and n=1, 11.1% in biatrial group) following the operation in the mid-term. Among the patients, there was no in-hospital mortality and no major postoperative complications such as stroke, sepsis, renal failure requiring dialysis, and prolonged respiratory failure.

Conclusion

Concomitant surgical cryoablation is an effective method for the treatment of atrial fibrillation, when performed concomitantly with other cardiac surgical procedures and results in very low atrial fibrillation recurrence, even in robotic surgery.

Assessment of the effect of left atrial cryoablation enhanced by ganglionated plexi ablation in the treatment of atrial fibrillation in patients undergoing open heart surgery

BACKGROUND

The aim of our study was to investigate, whether enhancement of left atrial cryoablation by ablation of the autonomic nervous system of left atrium leads to influencing the outcomes of surgical treatment of atrial fibrillation in patients with structural heart disease undergoing open-heart surgery.

METHODS

The observed patient file consisted of 100 patients, who have undergone a combined open-heart surgery at our department between July 2012 and December 2014. The patients were indicated for the surgical procedure due to structural heart disease, and suffered from paroxysmal, persistent, or long-standing persistent atrial fibrillation. In all cases, left atrial cryoablation was performed in the extent of isolation of pulmonary veins, box lesion, connecting lesion with mitral annulus, amputation of the left atrial appendage and connecting lesion of the appendage base with left pulmonary veins. Furthermore, 35 of the patients underwent mapping and radiofrequency ablation of ganglionated plexi, together with discision and ablation of the ligament of Marshall (Group GP). A control group was consisted of 65 patients without ganglionated plexi intervention (Group LA). The main primary outcome was establishment and duration of sinus rhythm in the course of one-year follow-up.

RESULTS

Evaluation of the number of patients with a normal sinus rhythm in per cent has shown comparable values in both groups (Group GP - 93.75%, Group LA - 86.67%, p = 0.485); comparable results were also observed in patients with normal sinus rhythm without anti-arrhythmic treatment in the 12th month (Group GP - 50%, Group LA - 47%, p = 0.306). We have not observed any relation between the recurrence of atrial fibrillation and the presence of a mitral valve surgery, or between the presence of a mitral and tricuspid valves surgery and between the left atrial diameter > 50 mm.

CONCLUSIONS

Enhancement of left atrial cryoablation by gangionated plexi ablation did not influence the outcomes of surgical ablation due to atrial fibrillation in our population in the course of 12-month follow-up.

TRIAL REGISTRATION

The study was approved retrospectively by the Ethics Committee of the University Hospital Ostrava ( reference number 867/2016).

Results of Cryoablation for Atrial Fibrillation Concomitant With Video-Assisted Minimally Invasive Mitral Valve Surgery

Interest in minimally invasive video-assisted mitral valve surgery (MIMVS) is rapidly growing. Data on concomitant atrial fibrillation (AF) ablation to MIMVS are still lacking. The present study investigates the long-term results of AF cryoablation concomitant to MIMVS. From October 2006-September 2014, 68 patients with mitral valve disease (age 65.9 ± 11.1 years, 34 men out of 68 patients, Euroscore log 5.4 ± 4.5) and drug-resistant AF underwent MIMVS via right minithoracotomy and concomitant left-sided AF endocardial cryoablation (Cryoflex Medtronic, Minneapolis, MN). Patients were independently followed up by cardiological outpatient visits and underwent electrophysiological study when indicated. In total, 44 out of 68 patients (64.7%) underwent mitral valve repair and 8 patients (11.8%) also received concomitant tricuspid valve surgery. One procedure was electively converted to full sternotomy (1.5%). Total clamp time was 97.6 ± 22.8 minutes. In March 2015, 60 patients were alive and completed the follow-up after a mean of 3.4 ± 2.0 years following the procedure. In all, 48 patients (80%) presented sinus rhythm throughout the whole follow-up. Freedom from AF was respectively 95%, 87%, and 72% at 1, 3, and 5 years, respectively. We recorded 2 pacemaker implants (3.3%). A total of 3 patients suffered symptomatic recurrences (2 atypical atrial flutter and 1 atrial fibrillation) and underwent transcatheter ablation-all the 3 patients remained in stable sinus rhythm for the remaining follow-up. In conclusions, given the favorable long-term sinus rhythm maintenance rates of concomitant cryoablation, MIMVS can also be offered to patients with symptomatic AF. AF transcatheter ablation may easily avoid further symptomatic recurrences.

Atrial fibrillation: review of current treatment strategies

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in modern clinical practice, with an estimated prevalence of 1.5-2%. The prevalence of AF is expected to double in the next decades, progressing with age and increasingly becoming a global medical challenge. The first-line treatment for AF is often medical treatment with either rate control or anti-arrhythmic agents for rhythm control, in addition to anti-coagulants such as warfarin for stroke prevention in patient at risk. Catheter ablation has emerged as an alternative for AF treatment, which involves myocardial tissue lesions to disrupt the underlying triggers and substrates for AF. Surgical approaches have also been developed for treatment of AF, particularly for patients requiring concomitant cardiac surgery or those refractory to medical and catheter ablation treatments. Since the introduction of the Cox-Maze III, this procedure has evolved into several modern variations, including the use of alternative energy sources (Cox-Maze IV) such as radiofrequency, cryo-energy and microwave, as well as minimally invasive thoracoscopic epicardial approaches. Another recently introduced technique is the hybrid ablation approach, where in a single setting both epicardial thoracoscopic ablation lesions and endocardial catheter ablation lesions are performed by the cardiothoracic surgeon and cardiologist. There remains controversy surrounding the optimal approach for AF ablation, energy sources, and lesion sets employed. The goal of this article is review the history, classifications, pathophysiology and current treatment options for AF.

Ablation technology for the surgical treatment of atrial fibrillation

The Cox maze procedure for the surgical treatment of atrial fibrillation has been simplified from its original cut-and-sew technique. Various energy sources now exist which create linear lines of ablation that can be used to replace the original incisions, greatly facilitating the surgical approach. This review article describes the anatomy of the atria that must be considered in choosing a successful energy source. Furthermore the device characteristics, safety profile, mechanism of tissue injury, and ability to create transmural lesions of the various energy sources that have been used in the Cox maze procedure, along with the strengths and weaknesses of each device is discussed.

Hybrid Therapy for Atrial Fibrillation: where the Knife meets the Catheter

During the past decades there has been a consistent evolution of both surgical and catheter-based techniques for the treatment of stand-alone atrial fibrillation, as alternatives or in combination with anti-arrhythmic drugs. Transcatheter ablation has significantly improved outcomes, despite often requiring multiple procedures and with limited success rates especially in presence of persistent atrial fibrillation. Surgical procedures have dramatically evolved from the original cut-and-sew Maze operation, allowing nowadays for closed-chest epicardial ablations on the beating heart. Recently, the concept of a close collaboration between the cardiac surgeon and the electrophysiologist has emerged as an intriguing option in order to overcome the drawbacks and suboptimal results of both techniques; therefore, the hybrid approach has been proposed as a potentially more successful strategy, allowing for a patient-tailored therapeutical approach. We reviewed the recent advancements either from the transcatheter and surgical standpoint, with a peculiar focus on the current option to merge both techniques along with an up-to-date review of the preliminary clinical experiences with the hybrid, surgical-transcatheter treatment of stand-alone atrial fibrillation.

Evaluation of a novel cryoablation system: in vivo testing in a chronic porcine model

OBJECTIVE

Cryoablation is commonly used at present in the surgical treatment of atrial fibrillation (AF). However, there have been few studies examining the efficacy of the commonly used ablation devices. This report compares the efficacy of two cryoprobes in creating transmural endocardial lesions on the beating heart in a porcine model for chronic AF.

METHODS

In six Hanford miniature swine, the right atrial appendage and the inferior vena cava were isolated using a bipolar radiofrequency clamp to create areas of known conduction block. A connecting ablation line was performed endocardially via a purse string with the novel malleable 10-cm Cryo1 probe for 2 minutes at -40°C. Additional ablation lines were created with the Cryo1 and the 3.5-cm 3011 Maze Linear probe on the right and the left atrial wall. Epicardial activation mapping was performed before and immediately after ablation as well as 14 days postoperatively. Histologic examination was performed 14 days postoperatively.

RESULTS

Transmural lesions were confirmed in 83/84 cross-sections (99%) for the Cryo1 probe and in 40/41 cross-sections (98%) for the 3011 Maze Linear probe. There was no difference between the devices in lesion width (mean ± SD, Cryo1, 10.7 ± 3.5 mm; 3011, 10.0 ± 3.9 mm; P = 0.31), lesion depth (Cryo1, 4.5 ± 1.7 mm; 3011, 4.6 ± 1.5 mm; P = 0.74), or atrial wall thickness (Cryo1, 4.5 ± 1.8 mm; 3011, 4.7 ± 1.7 mm; P = 0.74). There was a conduction delay across the right atrial ablation line (20 ± 2 milliseconds vs 51 ± 8 milliseconds, P < 0.001) that remained unchanged at 14 days (51 ± 8 milliseconds vs 52 ± 10 milliseconds, P = 0.88).

CONCLUSIONS

The Cryo1 probe created transmural lesions on the beating heart, resulting in sustained conduction delay. Both probes had a similar performance in lesion geometry in this chronic animal model.

A review of current surgical treatment of patients with atrial fibrillation

Surgical therapy for patients with atrial fibrillation has undergone significant advances over the past 30 years. The Cox Maze III technique is currently the gold standard of care for these patients. However, Maze IV, a less complex procedure using alternative energy sources, is rapidly replacing the Cox Maze III in clinical practice. The use of alternative energy sources such as cryothermy and radiofrequency eliminates some of the "cut and sew" lesions of the Maze III, resulting in an easier and faster procedure with less morbidity. Video-assisted technology and hybrid procedures have further ushered in the future of surgical therapy. This article presents the latest surgical therapeutic options for patients with atrial fibrillation. The history of these procedures is presented, followed by a discussion of modern-era techniques, including concomitant ablation and standalone (also referred to as "lone") procedures. Finally, the article explores breaking developments and future directions for the surgical treatment of patients with atrial fibrillation.

Maze Procedures for Atrial Fibrillation, From History to Practice

Atrial fibrillation may result in significant symptoms, (systemic) thrombo-embolism, as well as tachycardia-induced cardiomyopathy with cardiac failure, and consequently be associated with significant morbidity and mortality. Nowadays symptomatic atrial fibrillation can be treated with catheter-based ablation, surgical ablation or hybrid approaches. In this setting a fairly large number of surgical approaches and procedures are described and being practised. It should be clear that the Cox-maze procedure resulted from building up evidence and experience in different steps, while some of the present surgical approaches and techniques are being based only on technical feasibility with limited experience, rather than on a process of consequent methodology. Some of the issues still under debate are whether or not the maze procedure can be limited to the left atrium or even to isolation of the pulmonary veins or that bi-atrial procedures are indicated, whether or not cardiopulmonary bypass is to be applied and which route of exposure facilitates an optimal result. In addition, maze procedures are not procedures guide by electrophysiological mapping. At least in theory not in all patients all lesions of the maze procedures are necessary. A history and aspects of current practise in surgical treatment of atrial fibrillation is presented.

Atrial function after left atrial epicardial cryoablation for atrial fibrillation in patients undergoing mitral valve surgery

PURPOSE

To explore the effects on atrial and ventricular function of restoring sinus rhythm (SR) after epicardial cryoablation and closure of the left atrial appendage (LAA) in patients with mitral valve disease and atrial fibrillation (AF) undergoing surgery.

METHODS

Sixty-five patients with permanent AF were randomized to mitral valve surgery combined with left atrial epicardial cryoablation and LAA closure (ABL group, n = 30) or to mitral valve surgery alone (control group, n = 35). Two-dimensional and Doppler echocardiography were performed before and 6 months after surgery.

RESULTS

At 6 months, 73% of the patients in the ABL group and 46% of the controls were in SR. Patients in SR at 6 months had a reduction in their left ventricular diastolic diameter while the left ventricular ejection fraction was unchanged. In patients remaining in AF, the left ventricular ejection fraction was lower than at baseline. The left atrial diastolic volume was reduced after surgery, more in patients with SR than AF. In patients in SR, the peak velocity during the atrial contraction and the reservoir function were lower in the ABL group than in the control group.

CONCLUSIONS

In patients in SR, signs of atrial dysfunction were observed in the ABL but not the control group. Atrial dysfunction may have existed before surgery, but the difference between the groups implies that the cryoablation procedure and/or closure of the LAA might have contributed.

Mid-term results of endoscopic mitral valve repair in combination with endocardial or epicardial ablation

OBJECTIVE

Concomitant ablative therapy for atrial fibrillation can be effective at converting patients to normal sinus rhythm and at maintaining a regular rhythm for at least 5 years. We provide herein a comparison of an endocardial approach using Cryoablation with an epicardial approach using a suction-based RF ablation technology.

METHODS

Between February 2004 and January 2009, 325 patients underwent an endoscopic mitral valve repair. Of those patients, 112 (35%) had a history of atrial fibrillation prior to the procedure, all of whom underwent a concomitant ablation procedure. The first group of 78 concomitant ablation patients underwent a left-sided endocardial ablation procedure using a Cryoablation device. The second group of 34 ablation patients underwent a left-sided epicardial ablation procedure using an internally cooled monopolar RF device. No significant differences existed between groups in the preoperative data. All ablated patients were treated by the same Amiodarone protocol. Patients were followed for a minimum of 6 months for determining each ablated patient's rhythm, medication use, and overall health status.

RESULTS

The AF-free rates of group I and group II patients were statistically equivalent for both ablation groups at all evaluation time points. None of the 112 patients treated with endoscopic mitral valve repair and ablative therapy experienced a specific patient injury attributable to ablation; no ablated patients died in hospital following the procedure; there were no esophageal perforations and no coronary artery stenosis due to the ablations in either ablation group. The rate of patients without AF was 74% in group I and 82% in group II in the 6-month follow-up. The group I pacemaker implantation rate of 14% was significantly higher than non-ablated group (4.7%), but the group II rate of 5.9% observed did not differ significantly from the non-ablated group.

CONCLUSIONS

It was shown with our results that one succeeds with the en bloc-ablation in treating patients with different kinds of atrial fibrillation with concurrent intervention in the mitral valve reliably and with a high rate. The combination of this procedure with endocardial interventional ablation technologies can possibly develop to a promising strategy in the hybrid therapy of the isolated chronic atrial fibrillation as a standalone procedure.

Three-dimensional spectral map of atrial fibrillation by a 64-channel magnetocardiogram

We verified the significance of 3-dimensional (3D) spectral mapping during atrial fibrillation (AFIB) using a 64-channel magnetocardiogram (MCG). The study consisted of 16 patients with valvular heart disease who had chronic AFIB. All 16 patients had surgical pulmonary vein (PV) isolation followed by valvular repair. We performed spectral mapping by fast Fourier transform analysis in nonaveraged 64-channel MCG data. The 3D spectral map was superimposed on a 3D heart polygon. At 1 year after surgical PV isolation for AFIB, followed by valve repair, 7 patients had restoration to sinus rhythm, and 9 patients remained in persistent AFIB. The preoperative mean 3D frequency of AFIB was 6.1 +/- 0.9 Hz in patients with restored sinus rhythm and 7.2 +/- 0.7 Hz in patients with sustained AFIB after PV isolation (P = .02). In addition, the preoperative 3D spectrum was distributed on the right side of the heart in patients with persistent AFIB. In conclusion, 3D spectral mapping using 64-channel MCG may represent a meaningful noninvasive strategy for patients with AFIB who receive an interventional procedure.

Prevention of Atrial Flutter With Cryoablation May Be Proarrhythmogenic

BACKGROUND

Atrial flutter is a serious problem after surgery for congenital heart disease.

METHODS

We performed an intraoperative linear one-minute cryolesion between a right atriotomy and the tricuspid annulus to prevent atrial flutter in 17 consecutive adult patients undergoing surgery for congenital heart disease. Coronary angiography and electrophysiology study using an electroanatomic mapping system to assess the conduction across the line and to try to induce atrial flutter were performed three months after the operation in 15 patients.

RESULTS

Eleven patients had bidirectional block in the cryolesion, four patients did not, and two patients refused the electrophysiology study and coronary angiography. All patients with terminal temperature below -151 degrees C had bidirectional block, while only one patient with terminal temperature above -151 degrees C had bidirectional block. No patient with bidirectional block and all patients without bidirectional block had inducible or spontaneous atrial flutter (p = 0.0007). No lesion of the right coronary artery was detected at coronary angiography.

CONCLUSIONS

The success rate was suboptimal and the intervention is potentially proarrhythmogenic in patients without block. Preventive strategies targeting atrial flutter should be validated with regard to the block rate achieved.