Christophe P. Teuwen

Direct Proof of Endo-Epicardial Asynchrony of the Atrial Wall During Atrial Fibrillation in Humans

Background—The presence of focal fibrillation waves during atrial fibrillation (AF) can, besides ectopic activity, also be explained by asynchronous activation of the atrial endo- and epicardial layer and transmurally propagating fibrillation waves. To provide direct proof of endo-epicardial asynchrony, we performed simultaneous high-resolution mapping of the right atrial endo- and epicardial wall during AF in humans. Method and Results—Intraoperative mapping of the endo- and epicardial right atrial wall was performed during (induced) AF in 10 patients with AF (paroxysmal: n=3; persistent: n=4; and longstanding persistent: n=3) and 4 patients without a history of AF. A clamp made of 2 rectangular 8×16 electrode arrays (interelectrode distance 2 mm) was inserted into the incision in the right atrial appendage. Recordings of 10 seconds of AF were analyzed to determine the incidence of asynchronous endo-epicardial activation times (≥15 ms) of opposite electrodes. Asynchronous endo-epicardial activation ranged between 0.9 and 55.9% without preference for either side. Focal waves appeared equally frequent at endocardium and epicardium (11% versus 13%; P=0.18). Using strict criteria for breakthrough (presence of an opposite wave within 4 mm and ⩽14 ms before the origin of the focal wave), the majority (65%) of all focal fibrillation waves could be attributed to endo-epicardial excitation. Conclusions—We provided the first evidence for asynchronous activation of the endo-epicardial wall during AF in humans. Endo-epicardial asynchrony may play a major role in the pathophysiology of AF and may offer an explanation why in some patients therapy fails.

Time Course of Atrial Fibrillation in Patients With Congenital Heart Defects

Background—The incidence of atrial fibrillation (AF) is rising in the aging patients with congenital heart defects (CHD). However, studies reporting on AF in patients with CHD are scarce. The aim of this multicenter study was to examine in a large cohort of patients with a variety of CHD: (1) the age of onset and initial treatment of AF, coexistence of atrial tachyarrhythmia and (2) progression of paroxysmal to (long-standing) persistent/permanent AF during long-term follow-up. Methods and Results—Patients (n=199) with 15 different CHD and documented AF episodes were studied. AF developed at 49±17 years. Regular atrial tachycardia (AT) coexisting with AF occurred in 65 (33%) patients; 65% initially presented with regular AT. At the end of a follow-up period of 5 (0–24) years, the ECG showed AF in 81 patients (41%). In a subgroup of 114 patients, deterioration from paroxysm of AF to (long-standing) persistent/permanent AF was observed in 29 patients (26%) after only 3 (0–18) years of the first AF episode. Cerebrovascular accidents/transient ischemic attacks occurred in 26 patients (13%), although a substantial number (n=16) occurred before the first documented AF episode. Conclusions—Age at development of AF in patients with CHD is relatively young compared with the patients without CHD. Coexistence of episodes of AF and regular AT occurred in a considerable number of patients; most of them initially presented with regular AT. The fast and frequent progression from paroxysmal to (long-standing) persistent or permanent AF episodes justifies close follow-up and early, aggressive therapy of both AT and AF.

Non-sustained ventricular tachycardia in patients with congenital heart disease: An important sign?

BACKGROUNDnSustained ventricular tachycardia (susVT) and ventricular fibrillation (VF) are observed in adult patients with congenital heart disease (CHD). These dysrhythmias may be preceded by non-sustained ventricular tachycardia (NSVT). The aims of this study are to examine the 1] time course of ventricular tachyarrhythmia (VTA) in a large cohort of patients with various CHDs and 2] the development of susVT/VF after NSVT.nnnMETHODSnIn this retrospective study, patients with VTA on ECG, 24-hour Holter or ICD-printout or an out-of-hospital-cardiac arrest due to VF were included. In patients with an ICD, the number of shocks was studied.nnnRESULTSnPatients (N=145 patients, 59% male) initially presented with NSVT (N=103), susVT (N=25) or VF (N=17) at a mean age of 40 ± 14 years. Prior to VTA, 58 patients had intraventricular conduction delay, 14 an impaired ventricular dysfunction and 3 had coronary artery disease. susVT/VF rarely occurred in patients with NSVT (N=5). Fifty-two (36%) patients received an ICD; appropriate and inappropriate shocks, mainly due to supraventricular tachycardia (SVT), occurred in respectively 15 (29%) (NSVT: N=1, susVT: N=9, VF: N=5) and 12 (23%) (NSVT: N=4, susVT: N=5, VF: N=3) patients.nnnCONCLUSIONSnVTA in patients with CHD appear on average at the age of 40 years. susVT/VF rarely developed in patients with only NSVT, whereas recurrent episodes of susVT/VF frequently developed in patients initially presenting with susVT/VF. Hence, a wait-and-see treatment strategy in patients with NSVT and aggressive therapy of both episodes of VTA and SVT in patients with susVT/VF seems justified.

Relevance of Conduction Disorders in Bachmann’s Bundle During Sinus Rhythm in Humans

Background—Bachmann’s bundle (BB) is considered to be the main route of interatrial conduction and to play a role in development of atrial fibrillation (AF). The goals of this study are to characterize the presence of conduction disorders in BB during sinus rhythm and to study their relation with AF. Methods and Results—High-resolution epicardial mapping (192 unipolar electrodes, interelectrode distance: 2 mm) of sinus rhythm was performed in 185 patients during coronary artery bypass surgery of whom 13 had a history of paroxysmal AF. Continuous rhythm monitoring was used to detect postoperative AF during the first 5 postoperative days. In 67% of the patients, BB was activated from right to left; in the remaining patients from right and middle (21%), right, central, and left (8%), or central (4%) site. Mean effective conduction velocity was 89 cm/s. Conduction block was present in most patients (75%; median 1.1%, range 0–12.8) and was higher in patients with paroxysmal AF compared with patients without a history of AF (3.2% versus 0.9%; P=0.03). A high amount of conduction block (>4%) was associated with de novo postoperative AF (P=0.02). Longitudinal lines of conduction block >10 mm were also associated with postoperative AF (P=0.04). Conclusions—BB may be activated through multiple directions, but the predominant route of conduction is from right to left. Conduction velocity across BB is around 90 cm/s. Conduction is blocked in both longitudinal and transverse direction in the majority of patients. Conduction disorders, particularly long lines of longitudinal conduction block, are more pronounced in patients with AF episodes.

Usefulness of Fragmented QRS Complexes in Patients With Congenital Heart Disease to Predict Ventricular Tachyarrhythmias

Fragmented QRS complexes (fQRS) on 12-lead electrocardiogram are known predictors of ventricular tachyarrhythmia (VTA) in patients with coronary artery disease. There is limited knowledge of the clinical implications of fQRS in patients with congenital heart defects (CHD). Aims of this study were to examine (1) the occurrence of fQRS in patients with various types of CHD and (2) whether fQRS is associated with development of VTA. This study was designed as retrospective case-control study. Patients with CHD with VTA were included and matched with control patients of the same age, gender, and CHD type. Clinical data and fQRS were analyzed and compared. The initial VTA episode developed in 139 patients with CHD at a mean age of 39 ± 14xa0years. Compared with controls (nxa0= 219, age 38 ± 13xa0years), QRS duration was longer in patients with VTA (110 vs 100xa0ms; p <0.01). Furthermore, fQRS was more frequently observed in patients with VTA in the last electrocardiogram before VTA (nxa0= 73 [53%] vs nxa0= 67 [31%]; p <0.001), especially in patients with sustained VTA (64%). Multiple conditional logistic regression demonstrated more fQRS (odds ratio [OR] 2.9, 95% confidence interval [CI] 1.5 to 5.8; pxa0= 0.002), nonsystemic ventricular dysfunction (OR 5.1, 95% CI 2.1 to 12.4; p <0.001), and more prolonged QRS complexes (OR 2.8, 95% CI 1.3 to 6.2; pxa0= 0.011) in patients with VTA. Therefore, the presence of fQRS on electrocardiogram may be a useful tool in daily clinical practice to identify patients at risk for developing VTA in patients with CHD, in addition to known predictors of VTA.

Tachyarrhythmia in patients with congenital heart disease: inevitable destiny?

The prevalence of patients with congenital heart disease (CHD) has increased over the last century. As a result, the number of CHD patients presenting with late, postoperative tachyarrhythmias has increased as well. The aim of this review is to discuss the present knowledge on the mechanisms underlying both atrial and ventricular tachyarrhythmia in patients with CHD and the advantages and disadvantages of the currently available invasive treatment modalities.

Atrial tachyarrhythmias after atrial switch operation for transposition of the great arteries: Treating old surgery with new catheters

The arterial switch operation has been the procedure of first choice for correction of transposition of the great arteries (TGA) for several decades now. However, a large number of adult patients with TGA nowadays were palliated previously by either a Mustard or a Senning procedure. Atrial tachyarrhythmias (ATs) are frequently observed during long-term follow-up of patients with TGA after these atrial switch corrections and are associated with both morbidity and mortality. Because of the complex postoperative anatomy in these patients, ablative therapy for these tachyarrhythmias can be challenging. The goals of this review are to discuss the most prevalent ATs in patients after the Mustard or Senning procedure and to summarize (long-term) outcomes of ablative therapy. In addition, recent developments in ablative therapy for ATs in this patient population are outlined.

Progression of late postoperative atrial fibrillation in patients with tetralogy of Fallot

ToF patients are at risk for ventricular deterioration at a relatively young age, which can be aggravated by AF development. Therefore, knowledge on AF development and its timespan of progression is essential to guide treatment strategies for AF.

Frequent atrial extrasystolic beats predict atrial fibrillation in patients with congenital heart defects

AimsnAtrial fibrillation (AF) is increasingly observed in patients with congenital heart defects (CHDs) who survive nowadays into adulthood. Yet, predictors of AF are scarce in this high-risk population. This study therefore examined the predictive ability of atrial extrasystole (AES) for development of AF in CHD patients.nnnMethods and resultsnAdult CHD patients who had a 24 h Holter registration were followed to determine who developed AF. A total of 573 patients (49% male, mean age 35 ± 12 years) were included; they had a simple/complete repaired CHD (n = 279), complex repaired CHD (n = 251), or univentricular heart (UVH, n = 43). Ageing (P < 0.0001), female gender (P = 0.028), UVH (P = 0.0010), and left atrial dilatation (P = 0.0025) were associated with the number of AES. During a median follow-up of 51.6 months (interquartile range 22.8-85.7), 29 patients (5%) developed de novo AF. An one-point increase in the number of logtotal-AES was associated with a two-fold higher risk of AF development (hazard ratio 1.95; 95% confidence interval 1.21-3.13; P = 0.016). C-statistic for left atrial dilatation, complexity, and age had a good discriminative ability for the incidence of AF with a C-statistic of 84.5%. The addition of the total number of AES/24 h to this model increased C-statistic to 88.4%.nnnConclusionnAtrial extrasystole occur relatively frequent in adult CHD patients compared with patients with other cardiac diseases. This is the first study that showed an association between an increased AES frequency and a higher risk of AF development in CHD patients.

Bachmann’s Bundle and interatrial conduction; comparing atrial morphology to electrical activity.

BACKGROUNDnThe Bachmann bundle (BB) is one of the major interatrial muscular connections. Macroscopic anatomy and electrophysiological properties of BB have so far not been linked, and differences in activation patterns are most likely due to anatomical variations.nnnOBJECTIVESnThe goals of this study were to analyze different activation patterns and couple those wavefronts to epicardial morphological structures on cadaveric hearts.nnnMETHODSnHigh-resolution epicardial mapping over BB during sinus rhythm was performed in 185 patients undergoing coronary artery bypass graft surgery. The epicardial atrial musculature was macroscopically examined in 19 postmortem dissected human hearts, which are different from those examined in the mapping study. The morphology of BB and surrounding interatrial connections were evaluated. Activation patterns were subsequently linked to morphological variance found in the dissected hearts.nnnRESULTSnEpicardial mapping showed that BB is activated in a right-to-left direction in the majority of patients. In almost one-third of patients, a wavefront emerging or entering in the middle of BB was also observed. In some patients, left-to-right activation of BB was observed. BB was macroscopically present in all postmortem hearts. In addition, a newly found posterosuperior bundle was consistently seen, joining BB from the posterior border over the interatrial groove. Other connections identified were the septopulmonary bundle and posterior interatrial connections.nnnCONCLUSIONnThe morphological interatrial connections correspond to the interatrial pathways observed with high-resolution epicardial mapping of BB. Of these connections, BB and the posterosuperior bundle seem to be most consistent, both morphologically and electrophysiologically.