Guillaume S.C. Geuzebroek

Thoracoscopic Video-Assisted Pulmonary Vein Antrum Isolation, Ganglionated Plexus Ablation and Periprocedural Confirmation of Ablation Lesions. First Results of a Hybrid Surgical-Electrophysiological Approach for Atrial Fibrillation

Background—Thoracoscopic pulmonary vein isolation (PVI) and ganglionated plexus ablation is a novel approach in the treatment of atrial fibrillation (AF). We hypothesize that meticulous electrophysiological confirmation of PVI results in fewer recurrences of AF during follow-up. Methods and Results—Surgery was performed through 3 ports bilaterally. Ganglionated plexi were localized and subsequently ablated. PVI was performed and entry and exit block was confirmed. Additional left atrial ablation lines were created and conduction block verified in patients with nonparoxysmal AF. The left atrial appendage was removed. Freedom of AF was assessed by ECGs and Holter monitoring every 3 months or during symptoms of arrhythmia. Antiarrhythmic drugs were discontinued after 3 months and oral anticoagulants were discontinued according to the guidelines. Thirty-one patients were treated (16 paroxysmal AF, 13 persistent AF, 2 long-standing persistent AF). Thirteen patients with nonparoxysmal received additional left atrial ablation lines. After 1 year, 19 of 22 patients (86%) had no recurrences of AF, atrial flutter, or atrial tachycardia and were not using antiarrhythmic drugs (11/12 paroxysmal, 7/9 persistent, and 1/1 long-standing persistent). Three patients had a sternotomy because of uncontrolled bleeding during thoracoscopic surgery. Four adverse events were 1 hemothorax, 1 pneumothorax, and 2 pneumonia. No thromboembolic complications or mortality occurred. Conclusions—Thoracoscopic surgery with PVI and ganglionated plexus ablation for AF is a safe and successful procedure with a single procedure success rate of 86% at 1 year. Electrophysiological guided thorough PVI and additional left atrial ablation line creation presumably contributes in achieving a high success rate in the surgical treatment of AF.

Effects of Acetylcholine and Noradrenalin on Action Potentials of Isolated Rabbit Sinoatrial and Atrial Myocytes

The autonomic nervous system controls heart rate and contractility through sympathetic and parasympathetic inputs to the cardiac tissue, with acetylcholine (ACh) and noradrenalin (NA) as the chemical transmitters. In recent years, it has become clear that specific Regulators of G protein Signaling proteins (RGS proteins) suppress muscarinic sensitivity and parasympathetic tone, identifying RGS proteins as intriguing potential therapeutic targets. In the present study, we have identified the effects of 1 μM ACh and 1 μM NA on the intrinsic action potentials of sinoatrial (SA) nodal and atrial myocytes. Single cells were enzymatically isolated from the SA node or from the left atrium of rabbit hearts. Action potentials were recorded using the amphotericin-perforated patch-clamp technique in the absence and presence of ACh, NA, or a combination of both. In SA nodal myocytes, ACh increased cycle length and decreased diastolic depolarization rate, whereas NA decreased cycle length and increased diastolic depolarization rate. Both ACh and NA increased maximum upstroke velocity. Furthermore, ACh hyperpolarized the maximum diastolic potential. In atrial myocytes stimulated at 2 Hz, both ACh and NA hyperpolarized the maximum diastolic potential, increased the action potential amplitude, and increased the maximum upstroke velocity. Action potential duration at 50 and 90% repolarization was decreased by ACh, but increased by NA. The effects of both ACh and NA on action potential duration showed a dose dependence in the range of 1–1000 nM, while a clear-cut frequency dependence in the range of 1–4 Hz was absent. Intermediate results were obtained in the combined presence of ACh and NA in both SA nodal and atrial myocytes. Our data uncover the extent to which SA nodal and atrial action potentials are intrinsically dependent on ACh, NA, or a combination of both and may thus guide further experiments with RGS proteins.

Increased amount of atrial fibrosis in patients with atrial fibrillation secondary to mitral valve disease.

OBJECTIVE Atrial fibrosis is related to atrial fibrillation but may differ in patients with mitral valve disease or lone atrial fibrillation. Therefore, we studied atrial fibrosis in patients with atrial fibrillation+mitral valve disease or with lone atrial fibrillation and compared it with controls. METHODS Left and right atrial appendages amputated during Maze III surgery for lone atrial fibrillation (n=85) or atrial fibrillation+mitral valve disease (n=26) were embedded in paraffin, sectioned, and stained with picrosirius red. Atria from 10 deceased patients without a cardiovascular history served as controls. A total of 1048 images (4-μm sections, 10-fold magnification, 4 images per appendage) were obtained and digitized. The percentage of fibrous tissue was calculated by quantitative morphometry. RESULTS Irrespective of the presence or absence of atrial fibrillation or mitral valve disease, more fibrous tissue was present in right atrial appendages than in left atrial appendages (12.7%±5.7% vs 8.2%±3.9%; P<.0001). The mean amount of fibrous tissue in the atria was significantly larger in patients with atrial fibrillation+mitral valve disease than in patients with lone AF and controls (13.6%±5.8%, 9.7%±3.2%, and 8.8%±2.4%, respectively; P<.01). No significant differences existed between patients with lone atrial fibrillation and patients without a cardiovascular history (controls). CONCLUSIONS Atria of patients with atrial fibrillation and mitral valve disease have more fibrosis than atria of patients with lone atrial fibrillation. However, patients with lone atrial fibrillation have an equal amount of atrial fibrosis compared with controls. These findings support the notion that fibrosis plays a more important role in the pathogenesis of atrial fibrillation secondary to mitral valve disease than in lone atrial fibrillation and potentially explains the relatively poor success of antiarrhythmic surgery in patients with mitral valve disease.

Totally thoracoscopic left atrial Maze: standardized, effective and safe

OBJECTIVES The totally thoracoscopic left atrial Maze (TT-Maze) is a relatively new surgical solution for the treatment of atrial fibrillation (AF). The procedure consists of a complete left atrial Maze, which is performed by video-assisted thoracoscopy with the use of radiofrequency ablation. We describe our rhythm results as well as our learning curve experience of the TT-Maze. METHODS To evaluate the learning curve, all consecutive patients who underwent a TT-Maze and were operated by one surgeon (Bart P. Van Putte) were included in the study. The endpoint of surgery was sinus rhythm with a bidirectional block of the box and pulmonary veins. RESULTS A total of 83 patients were included. Fifty percent of the patients had paroxysmal AF. The mean indexed left atrial volume was 44 ± 15 ml/m(2) and 38% of the patients had a previous catheter ablation for AF. During a mean follow-up of 10.9 ± 4.9 months, there were no major events. At latest follow-up, 82% of the patients did not have a single registration of AF or other atrial tachyarrhythmias longer than 30 s. Patients without AF were also free from anti-arrhythmic drugs in 90% of the cases, free from coumadins or direct oral anticoagulants in 63% of the cases and free from both in 58% of the cases. CONCLUSIONS After almost 1-year follow-up, the TT-Maze is proved to be a successful, safe and reproducible strategy for the treatment of all types of AF including patients with enlarged left atria and previously failed catheter ablation.

Totally thoracoscopic ablation for atrial fibrillation: a systematic safety analysis

Abstract Aims Thoracoscopic surgical ablation has evolved into a successful strategy for symptomatic atrial fibrillation (AF) refractory to other therapy. More widespread referral is limited by the lack of information on potential complications. Our aim was to systematically evaluate 30-day complications of totally thoracoscopic surgical ablation. Methods and results We retrospectively studied consecutive patients undergoing totally thoracoscopic surgical ablation at a referral centre in the Netherlands (2007–2016). Patients received pulmonary vein isolation, with additional lesion lines as needed, and left atrial appendage exclusion. The primary outcomes were freedom from any complications and freedom from irreversible complications at 30-days. Secondary outcomes included intra- and post-operative complications according to severity. Included were 558 patients with median age 62 years (interquartile range 56–68 years), 70% male and 53% with a previous failed catheter ablation. The cohort consisted of 43% paroxysmal AF, 47% persistent AF, and 10% long-standing persistent AF. Freedom from any 30-day complication was 88.2%, and from complications with life-long affecting consequences 97.5%. The intra-operative complication rate was 2.3% with no strokes or death observed. The median hospital length of stay was 4 days. The percentage of patients with major and minor complications at 30-days was 3.2% and 8.1%, respectively, with one patient dying of an ischaemic stroke. The only patient groups with excess complications were women aged ≥70 years and patients with a history of congestive heart failure. Conclusions Totally thoracoscopic ablation is associated with a low complication rate in a referral centre and may be a useful alternative to other rhythm control strategies.

The totally thoracoscopic left atrial maze procedure for the treatment of atrial fibrillation

The totally thoracoscopic left atrial maze (TT-maze) is a recent, minimally invasive surgical procedure for the treatment of atrial fibrillation, with promising results in terms of freedom from atrial fibrillation. The TT-maze consists of a bilateral, epicardial pulmonary vein isolation with the creation of a box using radiofrequency and exclusion of the left atrial appendage (LAA). In addition, the box is connected with the base of the LAA and furthermore with the mitral annulus with the so-called trigonum line. In this report, we describe our surgical approach and short-term results.

Neurokinin-3 receptor activation selectively prolongs atrial refractoriness by inhibition of a background K + channel

The cardiac autonomic nervous system (ANS) controls normal atrial electrical function. The cardiac ANS produces various neuropeptides, among which the neurokinins, whose actions on atrial electrophysiology are largely unknown. We here demonstrate that the neurokinin substance-P (Sub-P) activates a neurokinin-3 receptor (NK-3R) in rabbit, prolonging action potential (AP) duration through inhibition of a background potassium current. In contrast, ventricular AP duration was unaffected by NK-3R activation. NK-3R stimulation lengthened atrial repolarization in intact rabbit hearts and consequently suppressed arrhythmia duration and occurrence in a rabbit isolated heart model of atrial fibrillation (AF). In human atrial appendages, the phenomenon of NK-3R mediated lengthening of atrial repolarization was also observed. Our findings thus uncover a pathway to selectively modulate atrial AP duration by activation of a hitherto unidentified neurokinin-3 receptor in the membrane of atrial myocytes. NK-3R stimulation may therefore represent an anti-arrhythmic concept to suppress re-entry-based atrial tachyarrhythmias, including AF.The cardiac autonomic nervous system produces various neuropeptides, such as neurokinin substance-P (Sub-P), whose function remains largely unclear. Here, authors show that Sub-P causes a receptor-mediated prolongation of the atrial action potential through a reduced background potassium current, and prevents atrial fibrillation.

The maze operation as a surgical treatment of atrial fibrillation.

Abstract In this study we reviewed the history of the surgical treatment of atrial fibrillation (AF). Of the various types, the maze operation has become nowadays the most successful surgical treatment of AF with or without concomitant cardiac surgery. We report on our 10-year experience with conventional maze III surgery: 203 patients were operated on without in-hospital mortality and acceptable morbidity. Success defined as the freedom of Af and other supraventricular arrhythmias was 80.1% for the patients with lone AF and 64.5% for the patients with concomitant AF after a mean of 4 years after surgery. We conclude that despite the complexity of the maze III operation this approach remains the golden standard from which future surgical and other ablative treatments of AF will be derived.