Jan Nijs

Post-operative atrial fibrillation: a maze of mechanisms

Post-operative atrial fibrillation (POAF) is one of the most frequent complications of cardiac surgery and an important predictor of patient morbidity as well as of prolonged hospitalization. It significantly increases costs for hospitalization. Insights into the pathophysiological factors causing POAF have been provided by both experimental and clinical investigations and show that POAF is ‘multi-factorial’. Facilitating factors in the mechanism of the arrhythmia can be classified as acute factors caused by the surgical intervention and chronic factors related to structural heart disease and ageing of the heart. Furthermore, some proarrhythmic mechanisms specifically occur in the setting of POAF. For example, inflammation and beta-adrenergic activation have been shown to play a prominent role in POAF, while these mechanisms are less important in non-surgical AF. More recently, it has been shown that atrial fibrosis and the presence of an electrophysiological substrate capable of maintaining AF also promote the arrhythmia, indicating that POAF has some proarrhythmic mechanisms in common with other forms of AF. The clinical setting of POAF offers numerous opportunities to study its mechanisms. During cardiac surgery, biopsies can be taken and detailed electrophysiological measurements can be performed. Furthermore, the specific time course of POAF, with the delayed onset and the transient character of the arrhythmia, also provides important insight into its mechanisms. This review discusses the mechanistic interaction between predisposing factors and the electrophysiological mechanisms resulting in POAF and their therapeutic implications.

Beating-heart surgical treatment of atrial fibrillation with microwave ablation

BACKGROUND In this feasibility study, early results are presented of our first series of patients with microwave ablation for atrial fibrillation (AF) on the beating heart. METHODS From June 2001 until December 2001, a total of 24 patients underwent beating-heart epicardial ablation for AF. With a microwave antenna, the left and right pulmonary veins were isolated and connected to each other followed by amputation of the left atrial appendage. Subsequently, patients underwent either off-pump coronary artery bypass graft or valve surgery on pump. The mean age of the patients was 67.4 +/- 6 years. Three patients experienced paroxysmal atrial fibrillation and all others chronic AF. Mean left atrial diameter was 5.4 +/- 0.6 cm, and mean ablation time was 13 min. RESULTS All procedures but one were completed successfully on the beating heart. All patients were in sinus rhythm after the procedure. A total of 15 patients experienced periods with postoperative AF during hospital stay; 9 of these patients were discharged with AF. All patients received either sotalol or amiodarone. At latest follow-up (3 to 9 months), 20 of 23 patients were in sinus rhythm. CONCLUSIONS With microwave ablation, electrical isolation of the pulmonary veins can be achieved epicardially without cardiopulmonary bypass support.

Indices of bipolar complex fractionated atrial electrograms correlate poorly with each other and atrial fibrillation substrate complexity

BACKGROUND The pathophysiological relevance of complex fractionated atrial electrograms (CFAE) in atrial fibrillation (AF) remains poorly understood. OBJECTIVE The aim of this study was to comprehensively investigate how bipolar CFAE correlates with unipolar electrogram fractionation and the underlying electrophysiological substrate of AF. METHODS Ten-second unipolar AF electrograms were recorded using a high-density electrode from the left atrium of 20 patients with AF (10 with persistent AF and 10 with paroxysmal AF) undergoing cardiac surgery. Semiautomated bipolar CFAE algorithms: complex fractionated electrogram-mean, interval confidence interval, continuous electrical activity, average complex interval, and shortest complex interval were evaluated against AF substrate complexity measures following fibrillation wave reconstruction derived from local unipolar activation time. The effect of interelectrode spacing and electrode orientation on bipolar CFAE was also examined. RESULTS All 5 semiautomated bipolar CFAE algorithms showed poor correlation with each other and AF substrate complexity measures (conduction velocity, number of waves or breakthroughs per AF cycle, and electrical dissociation). Bipolar CFAE also correlated poorly with fractionation index derived from unipolar electrograms. Increased interelectrode spacing resulted in an increase in bipolar CFAE detected except for the interval confidence interval algorithm. CFAE appears unaffected by bipolar electrode orientation (vertical vs horizontal). By contrast, unipolar fractionation index correlated well with AF substrate complexity measures and can be regarded as a marker for conduction block. CONCLUSION The lack of pathophysiological relevance of bipolar CFAE analysis may in part contribute to the divergent and limited success rates of catheter ablation strategies targeting CFAE.

A prospective randomized multicenter comparison on health-related quality of life: the value of add-on arrhythmia surgery in patients with paroxysmal, permanent or persistent atrial fibrillation undergoing valvular and/or coronary bypass surgery.

Quality of Life After Add‐on Arrhythmia Surgery Introduction: This is a multicenter, prospective, randomized controlled trial to determine the effect of add‐on arrhythmia surgery on health‐related quality of life during 1‐year follow‐up of cardiac surgery patients with atrial fibrillation.

3D-echo in preoperative assessment of aortic cusps effective height

Effective height, which represents the height difference between the central free margins and the aortic insertion lines can be easily determined by 2-D echocardiography and allows for identification of prolapse in the native cusps and assessment of prolapse correction after valve repair. Nonetheless, it allows to see only two of three aortic valve (AV) coaptation planes and this may lead to misunderstanding of the underlying pathophysiological mechanism for aortic regurgitation and hence in unsuccessful repair. In contrast, 3D transoesophageal echocardiography and multiple plane reconstruction lets visualize all the three coaptation planes between the AV cusps and it represents an invaluable tool in the assessment of aortic valve geometry. It is highly recommendable before AV repair to accurately study the complex three dimensional cusps anatomy and their geometric interrelation with aortic root.

Unmasking a naked left atrial appendage closure device: A case of a silent embolic threat

Patients with atrial fibrillation (AF) have a higher risk for thromboembolic events, for which oral anticoagulation is the first choice of therapy. For patients in whom anticoagulation is contraindicated, new therapeutic approaches are needed. Recent studies have shown the noninferiority of percutaneous closure of the left atrial appendage (LAA) compared to oral anticoagulation. Therefore, these devices can be a potential alternative therapy for preventing thromboembolic complications in patients with AF. However, with intracardiac devices the amount of foreign material can cause thrombus formation. Here we describe a case of intraoperative discovery of a thrombus on an Amplatzer cardiac plug. The thrombus was not visible during peroperative transesophageal echocardiography.

Implantable cardioverter defibrillator therapy in young individuals: comparison of conventional and subcostal approaches-a single-centre experience.

Aim The aim of our study is to compare two approaches of implantable cardiac defibrillator (ICD) implantation, conventional (supra/subpectoral) and subcostal in young adults in terms of procedural complications and adverse events encountered during follow-up. Methods and results From January 2007 to December 2013, all patients under the age of 50 years who received an ICD in our centre were included in this study. Patients hospital records were analysed for procedural complications and adverse events during follow-up until December 2014. Data from device on first interrogation after implantation and on follow-up were also noted. A total of 106 patients of which 40.6% had Brugadas syndrome (65.1% male, age 33.6 ± 10.97 years) were included in analysis; 71 (61%) had ICD placed in (sub/supra) pectoral and 35 (33%) in subcostal position. Only seven patients received an epicardial lead system. During the follow-up period of 2.1 ± 1.8 years, 84.90% of the patients had no adverse events. Most of the complications, procedural and during follow-up, occur in conventionally placed, pectoral ICD. Lead follow-up data in both groups, conventional and subcostal, showed no difference in right ventricular (RV) shock impedance and R wave sensing, P-value = 0.56 and 0.77, respectively. Lead survival was 95 and 97%, respectively, in conventional and subcostal groups over a mean follow-up of 2.1 ± 1.8 years. Log-rank test for lead survival was not significant in terms of site of implantation. Conclusion To the best our knowledge, this is the first study demonstrating subcostal ICD placement in young adults and resulting in equivalent to better outcomes when compared with conventionally placed pectoral ICD. Subcostal ICD placement might be considered an alternative option in young adults as it results in better procedural outcomes and also comparable rate of adverse events during follow-up, but bigger studies with a larger number of patients are needed for a definitive conclusion.

Retrograde Flow in the Descending Thoracic Aorta Magnetic Resonance Imaging of an Apicoaortic Conduit

A 55-year-old woman was admitted with congestive heart failure caused by severe aortic valve stenosis. Conventional aortic valve replacement could not be performed because of a porcelain aorta. Thus, via an anterolateral thoracotomy, a Hancock 20-mm prosthesis (Medtronic Inc., Minneapolis, Minn) was inserted into the apex of the left ventricle and connected to a Carbomedics Carbo-Seal 21-mm valved conduit (Sulzer Carbomedics Inc., Austin, …A 55-year-old woman was admitted with congestive heart failure caused by severe aortic valve stenosis. Conventional aortic valve replacement could not be performed because of a porcelain aorta. Thus, via an anterolateral thoracotomy, a Hancock 20-mm prosthesis (Medtronic Inc., Minneapolis, Minn) was inserted into the apex of the left ventricle and connected to a Carbomedics Carbo-Seal 21-mm valved conduit (Sulzer Carbomedics Inc., Austin, Tex), which in turn was sewn onto the descending aorta in an end-to-side fashion (Figure and Movie I in the online-only Data Supplement). Magnetic resonance (MR) imaging was performed to evaluate postoperative anatomy, function, and flow. Fourchamber (Figure, A, and Movie II in the online-only Data Supplement) and transverse (Figure, B, and Movie III in the online-only Data Supplement) cine MR imaging provided excellent delineation of the insertions and course of the apicoaortic conduit (asterisk). MR flow measurements revealed a sufficient combined stroke volume at rest (ascending aorta, 16 mL; conduit, 39 mL) and estimated the distribution of flow over the ascending aorta, descending aorta, and conduit (Figure, D). Cine MR imaging showed competitive flow in the aortic arch and retrograde flow in the descending aorta (Movie IV in the online-only Data Supplement).

Images in cardiovascular medicine: Retrograde flow in the descending thoracic aorta: magnetic resonance imaging of an apicoaortic conduit.

A 55-year-old woman was admitted with congestive heart failure caused by severe aortic valve stenosis. Conventional aortic valve replacement could not be performed because of a porcelain aorta. Thus, via an anterolateral thoracotomy, a Hancock 20-mm prosthesis (Medtronic Inc., Minneapolis, Minn) was inserted into the apex of the left ventricle and connected to a Carbomedics Carbo-Seal 21-mm valved conduit (Sulzer Carbomedics Inc., Austin, …A 55-year-old woman was admitted with congestive heart failure caused by severe aortic valve stenosis. Conventional aortic valve replacement could not be performed because of a porcelain aorta. Thus, via an anterolateral thoracotomy, a Hancock 20-mm prosthesis (Medtronic Inc., Minneapolis, Minn) was inserted into the apex of the left ventricle and connected to a Carbomedics Carbo-Seal 21-mm valved conduit (Sulzer Carbomedics Inc., Austin, Tex), which in turn was sewn onto the descending aorta in an end-to-side fashion (Figure and Movie I in the online-only Data Supplement). Magnetic resonance (MR) imaging was performed to evaluate postoperative anatomy, function, and flow. Fourchamber (Figure, A, and Movie II in the online-only Data Supplement) and transverse (Figure, B, and Movie III in the online-only Data Supplement) cine MR imaging provided excellent delineation of the insertions and course of the apicoaortic conduit (asterisk). MR flow measurements revealed a sufficient combined stroke volume at rest (ascending aorta, 16 mL; conduit, 39 mL) and estimated the distribution of flow over the ascending aorta, descending aorta, and conduit (Figure, D). Cine MR imaging showed competitive flow in the aortic arch and retrograde flow in the descending aorta (Movie IV in the online-only Data Supplement).

Unreliability of aortic size index to predict risk of aortic dissection in a patient with Turner syndrome

Aortic size index (ASI) has been proposed as a reliable criterion to predict risk for aortic dissection in Turner syndrome with significant thresholds of 20-25 mm/m(2). We report a case of aortic arch dissection in a patient with Turner syndrome who, from the ASI thresholds proposed, was deemed to be at low risk of aortic dissection or rupture and was not eligible for prophylactic surgery. This case report strongly supports careful monitoring and surgical evaluation even when the ASI is < 20 mm/m(2) if other significant risk factors are present.