[Efficacy and safety of various energy sources and application techniques for the surgical treatment of atrial fibrillation]

Outcomes of surgical ablation for atrial fibrillation in on- versus off-pump coronary artery bypass grafting

OBJECTIVES

A considerable number of patients undergoing coronary artery bypass grafting surgery suffer from atrial fibrillation and should be treated concomitantly. This manuscript evaluates the impact of on-pump versus off-pump bypass grafting on the applied lesion set and rhythm outcome.

METHODS

Between January 2017 and April 2020, patients who underwent combined bypass grafting and surgical ablation for atrial fibrillation were consecutively enrolled in the German CArdioSurgEry Atrial Fibrillation registry (CASE-AF, 17 centres). Data were prospectively collected. Follow-up was planned after one year.

RESULTS

A total of 224 patients were enrolled. No differences in baseline characteristics were seen between on- and off-pump bypass grafting, especially not in type of atrial fibrillation and left atrial size. In the on-pump group (n = 171, 76%), pulmonary vein isolation and an extended left atrial lesion set were performed more often compared to off-pump bypass grafting (58% vs 26%, 33 vs 9%, respectively, P < 0.001). In off-pump bypass grafting a box isolating the atrial posterior wall was the dominant lesion (72% off-pump vs 42% on-pump, P < 0.001). Left atrial appendage management was comparable in on-pump versus off-pump bypass grafting (94% vs 91%, P = 0.37). Sinus rhythm at follow-up was confirmed in 61% in the on-pump group and in 65% in the off-pump group (P = 0.66). No differences were seen in in-hospital or follow-up complication-rates between the two groups.

CONCLUSIONS

In coronary artery bypass grafting patients undergoing concomitant atrial fibrillation ablation, our data suggests that the technique applied for myocardial revascularization (off-pump vs on-pump) leads to differences in the ablation lesion set, but not in safety and effectiveness.

Characteristics of the new AtriCure cryoFORM® cryoablation probe for the surgical treatment of cardiac arrhythmias

INTRODUCTION

Atrial fibrillation has a significant impact on patient mortality and morbidity. In particular, stroke is a frequent complication associated with atrial fibrillation. In recent years, various treatment options have been developed that are based on the elimination of atypical electrically active atrial areas. Areas covered: This manuscript presents a new cryoablation probe from AtriCure Inc. In addition to describing the characteristics of the probe, we also discuss atrial fibrillation and its surgical therapy options as well as the basics of cryosurgery. The cryoFORM® cryoablation probe is an ablation system developed for cardiothoracic surgeons that utilizes nitrous oxide (N₂O) to create continuous transmural lesions that block propagation of atrial activation. The main features of the probe are an excellent working capacity due to the use of N₂O, high flexibility, and, in combination with the cryoICE® Box V6, an active defrost mode for quick detachment. Expert commentary: The cryoFORM® ablation probe is a new device for the treatment of atrial fibrillation using N₂O as an energy source. The probe is made from stainless steel and has a corrugated surface, a design that provides a higher flexibility than the cryoICE probe.

Incremental risk of the Cox-maze IV procedure for patients with atrial fibrillation undergoing mitral valve surgery

OBJECTIVE

More than 50% of atrial fibrillation surgery occurs in the setting of mitral valve surgery. Despite this, no risk models have been validated for concomitant arrhythmia surgery. The purpose of the present study was to quantify the additional risk of performing the Cox-maze IV procedure for patients undergoing mitral valve surgery.

METHODS

From January 2002 to June 2011, 213 patients with mitral valve disease and preoperative atrial fibrillation underwent mitral valve surgery only (n = 109) or in conjunction with a Cox-maze IV procedure (n = 104). The operative mortality for the mitral valve procedure alone was predicted for each group using the Society of Thoracic Surgeons perioperative risk calculator. The risk attributed to the added Cox-maze IV procedure was calculated by comparing the predicted mortality rate of an isolated mitral valve procedure and the actual mortality rate of mitral valve surgery with a concomitant Cox-maze IV procedure.

RESULTS

For patients not undergoing a Cox-maze IV procedure, the predicted and actual postoperative mortality rate was 5.5% and 4.6% (5 of 109), respectively. For patients receiving mitral valve surgery and a concomitant Cox-maze IV, the predicted and actual postoperative mortality of the mitral valve procedure was 2.5% and 2.9% (3 of 104), respectively, and not significantly different. Patients not offered a Cox-maze IV procedure had significantly more serious comorbidities.

CONCLUSIONS

For patients with atrial fibrillation and mitral valve disease undergoing mitral valve surgery, the decision to offer a concomitant Cox-maze IV procedure will be influenced by the underlying comorbid conditions. Nonetheless, in selected lower risk patients, the addition of a Cox-maze IV procedure did not significantly affect the procedural mortality.

Surgical therapy of atrial fibrillation

Atrial fibrillation (AF) can be found in an increasing number of cardiac surgical patients due to a higher patient's age and comorbidities. Atrial fibrillation is known, however, to be a risk factor for a greater mortality, and one aim of intraoperative AF treatment is to approximate early and long-term survival of AF patients to survival of patients with preoperative sinus rhythm. Today, surgeons are more and more able to perform less complex, that is, minimally invasive cardiac surgical procedures. The evolution of alternative ablation technologies using different energy sources has revolutionized the surgical therapy of atrial fibrillation and allows adding the ablation therapy without adding significant risk. Thus, the surgical treatment of atrial fibrillation in combination with the cardiac surgery procedure allows to improve the postoperative long-term survival and to reduce permanent anticoagulation in these patients. This paper focuses on the variety of incisions, lesion sets, and surgical techniques, as well as energy modalities and results of AF ablation and also summarizes future trends and current devices in use.

Epicardial neural ganglionated plexus of ovine heart: anatomic basis for experimental cardiac electrophysiology and nerve protective cardiac surgery

BACKGROUND

Sheep are routinely used in experimental cardiac electrophysiology and surgery.

OBJECTIVE

The purpose of this study was to (1) ascertain the topography and architecture of the ovine epicardial neural plexus (ENP), (2) determine the relationships of ENP with vagal and sympathetic cardiac nerves and ganglia, and (3) evaluate gross anatomic differences and similarities of ENP in humans, sheep, and other species.

METHODS

Ovine ENP and extrinsic sympathetic and vagal nerves were stained histochemically for acetylcholinesterase in whole heart and/or thorax-dissected preparations from 23 newborn lambs, with subsequent examination by stereomicroscope.

RESULTS

Intrinsic cardiac nerves extend from the venous part of the ovine heart hilum along the roots of the cranial (superior) caval and left azygos veins to both atria and ventricles via five epicardial routes: dorsal right atrial, middle dorsal, left dorsal, right ventral, and ventral left atrial nerve subplexuses. Intrinsic nerves proceeding from the arterial part of the heart hilum along the roots of the aorta and pulmonary trunk extend exclusively into the ventricles as the right and left coronary subplexuses. The dorsal right atrial, right ventral, and middle dorsal subplexuses receive the main extrinsic neural input from the right cervicothoracic and right thoracic sympathetic T(2) and T(3) ganglia as well as from the right vagal nerve. The left dorsal is supplied by sizeable extrinsic nerves from the left thoracic T(4)-T(6) sympathetic ganglia and the left vagal nerve. Sheep hearts contained an average of 769 +/- 52 epicardial ganglia. Cumulative areas of epicardial ganglia on the root of the cranial vena cava and on the wall of the coronary sinus were the largest of all regions (P <.05).

CONCLUSION

Despite substantial interindividual variability in the morphology of ovine ENP, right-sided epicardial neural subplexuses supplying the sinoatrial and atrioventricular nodes are mostly concentrated at a fat pad between the right pulmonary veins and the cranial vena cava. This finding is in sharp contrast with a solely left lateral neural input to the human atrioventricular node, which extends mainly from the left dorsal and middle dorsal subplexuses. The abundance of epicardial ganglia distributed widely along the ovine ventricular nerves over respectable distances below the coronary groove implies a distinctive neural control of the ventricles in human and sheep hearts.

[Complications after ablation of supraventricular tachycardias]

The ablation of supraventricular tachycardias is a curative procedure with high success rates. Due to considerably improvement of quality of life, it becomes the therapy of first choice in nearly all kinds of symptomatic supraventricular reentry tachycardias. Following the guidelines for the management of patients with atrial fibrillation, pulmonary vein isolation is still second choice of therapy after ineffective medical treatment. In experienced electrophysiological centres a complication rate of < 2% and an intention to treat mortality of < 0.1% can be expected.