The relationship between sinus node dysfunction, bradycardia-mediated atrial remodelling, and post-operative atrial flutter in patients with congenital heart defects.
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Atrial Flutter↗
Biomedical subjects
Natasja M S de Groot
Publications and source records attributed to Natasja M S de Groot.
Automatic mapping of human atrial fibrillation by template matching.
BACKGROUND: The high spatiotemporal variation in morphology of fibrillation electrograms makes mapping of atrial fibrillation (AF) a difficult and burdensome task. OBJECTIVES: The purpose of this study was to evaluate the results of automatic detection of fibrillation electrograms by a template matching technique. METHODS: During cardiac surgery in 25 patients without a history of AF, paroxysms of AF were induced by rapid atrial pacing. A mapping array of 244 unipolar electrodes (3.6-cm diameter, 2.25-mm interelectrode distance) was positioned on the free wall of the right atrium. All fibrillation electrograms were correlated with a mathematically constructed library of 128 potentials of different duration, RS ratio, and short double components. The moments of maximal correlation, coinciding with the negative deflection in the fibrillation potentials, were used to create fibrillation maps. RESULTS: In each patient, a segment of 18.6 +/- 3.8 seconds of AF was analyzed, resulting in 80 to 130 maps per patient. The output of the automatic algorithm was compared with careful manual analysis by an experienced investigator. Of the total database of 398,796 fibrillation potentials, 93.6% +/- 4.2% resulted in a good correlation with one of the templates in the library (correlation coefficient >= 0.7). At a correlation threshold of 0.6, on average template matching yielded slightly more false-positive than false-negative detections (sensitivity 96.6% +/- 2.5%, positive predictive value 94.3% +/- 5.4%). The majority of false-positive detections were due to electrotonic potentials recorded along the lateral boundaries of the fibrillation waves. This led to a slight overlap of fibrillation waves but not to false detection of nonexisting wavefronts. Undersensing was mainly due to the presence of long double and fractionated potentials (2.6%) that were not represented in the template library. Fractionated parts in the electrograms were identified by failure of template matching and can be analyzed separately. CONCLUSION: Template matching is a useful technique for characterizing unipolar fibrillation electrograms and for visualizing the complex activation patterns during AF. It allows automatic evaluation of the electropathologic substrate of AF on an individual basis.
Adult↗
Euro Heart Survey on adult congenital heart disease: concern for the complexity of care.
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Adult↗
Ablation of focal atrial arrhythmia in patients with congenital heart defects after surgery: role of circumscribed areas with heterogeneous conduction.
BACKGROUND: In patients late after surgical repair of congenital heart disease (CHD), areas with abnormal electrophysiologic properties may serve as slow conducting pathways within a macroreentrant circuit or may be the source of focal atrial tachycardia. OBJECTIVES: The purpose of this study was to evaluate the role of abnormal areas during focal atrial tachycardia prior to ablation. METHODS: Electroanatomic activation mapping of 62 atrial tachycardias was performed in 43 consecutive patients (37 +/- 12 years) after surgical repair of CHD. The mechanism of atrial tachycardia was scar related intra-atrial reentry (n = 27), cavotricuspid-related atrial flutter (n = 21), atrial fibrillation (n = 2), or focal atrial tachycardia (n = 10). During intra-atrial reentry, channels of slow conduction could be identified in all patients. Subsequent ablation was directed toward connecting two nonconductive borders. The site of origin during focal atrial tachycardia showed fractionated potentials and/or continuous electrical activity. RESULTS: Ablation directed at isolating the source area resulted in termination of focal atrial tachycardia in all cases. In two patients, ablation of an area showing continuous electrical activity giving rise to fibrillatory conduction resulted in termination of atrial fibrillation. Ablation of intra-atrial reentry was successful in 70%. Atrial flutter and focal atrial tachycardia were successfully ablated in all patients. No complications were observed. CONCLUSION: In patients with surgically corrected CHD, atrial tachycardia most often is caused by a macroreentrant mechanism but in some is the result of a focal mechanism. Areas of abnormal conduction may serve not only as a zone of slow conduction within a macroreentrant circuit but also as the site of origin of a focal atrial arrhythmia. Catheter ablation directed at "source isolation" is effective in eliminating focal atrial tachycardia in patients with CHD.
Adolescent↗
Fusion of electroanatomical activation maps and multislice computed tomography to guide ablation of a focal atrial tachycardia in a fontan patient.
INTRODUCTION: Ablation of atrial tachycardia (AT) occurring late after cardiac surgery for congenital heart disease can be challenging due to the complexity of the arrhythmogenic substrate. METHODS AND RESULTS: We performed an ablation procedure in a Fontan patient with an AT using a new approach combining 3D electroanatomical mapping with multislice computed tomography (MSCT). This technique visualizes the position of the catheter in relation to the endocardium, thereby improving delineation of scar tissue. The AT had a focal origin located between areas of scar tissue and was successfully ablated at the earliest activated site. CONCLUSION: Ablation of complex arrhythmias can be facilitated by fusion of electroanatomical map and MSCT.
Abnormalities, Multiple↗
S-wave predominance of epicardial electrograms during atrial fibrillation in humans: indirect evidence for a role of the thin subepicardial layer.
OBJECTIVES: The purpose of this study was to characterize the morphology of fibrillation electrograms in patients in order to provide insight into the underlying electropathologic substrate of atrial fibrillation (AF). BACKGROUND: Electrograms recorded during AF show a high degree of spatiotemporal variation. METHODS: AF was induced by rapid atrial pacing in 25 patients undergoing cardiac surgery. A unipolar mapping array of 244 electrodes was positioned on the free wall of the right atrium to record multiple epicardial fibrillation electrograms. Local anisotropy in conduction and epicardial wavefront curvature during AF were determined by fitting the best quadratic surface on the activation times of rectangular areas of 3 x 3 electrodes. RESULTS: During AF, unipolar epicardial electrograms revealed a clear predominance of S waves. The average RS difference during type I and II AF was -0.15 +/- 0.08 and -0.22 +/- 0.08. During type III AF, the predominance of S waves was less prominent (-0.07 +/- 0.05; P < .005). In all types of AF, the degree of anisotropy in conduction was remarkably low (anisotropy ratio: 1.24 +/- 0.09), and no clear directional effect on the relative amplitude of R and S waves was found. There was a weak relationship between local curvature of wavefronts and RS difference (r = 0.23; P < .01). Computer simulations showed that the negative RS difference could result from transmural activation in an epicardial to endocardial direction. CONCLUSIONS: The clear predominance of S waves in epicardial fibrillation electrograms is not due to anisotropy and can only be partly explained by a high curvature of fibrillation waves. Predominant epicardial to endocardial activation seems to be important in producing rS electrograms on the epicardium. This finding provides indirect evidence that the thin epicardial layer of atrial myocardium plays an important role in propagation of fibrillation waves.
Adult↗
Voltage and activation mapping: how the recording technique affects the outcome of catheter ablation procedures in patients with congenital heart disease.
BACKGROUND: Endocardial mapping is mandatory before radiofrequency catheter ablation (RFCA). Mapping can be performed with either unipolar or bipolar recordings. Impact of the recording technique used was studied in patients with and without structural heart disease using the 3D electroanatomic CARTO mapping system. METHODS AND RESULTS: Patients (n=44; 16 males; age 43+/-16 years) referred for RFCA of atrial flutter (AFL, n=18), focal atrial tachycardia (FAT, n=4), AV nodal reentrant tachycardia (AVNRT, n=5), or scar-related atrial reentrant tachycardia (IART, n=17) were studied. Voltage and activation maps were constructed. Unipolar and bipolar voltage distribution in the different groups was studied to establish a cutoff voltage value to facilitate delineation of scar tissue. Electrograms were recorded during tachycardia (FAT: n=246, cycle length [CL]=449+/-35 ms; AVNRT: n=182, CL=359+/-47 ms; AFL: n=1164, CL=255+/-56 ms; IART: n=2431, CL=280+/-74 ms). Unipolar voltages were greater than bipolar voltages (P<0.001). Unipolar voltages < or =1.0 mV were equally distributed in both AFL and IART patients. Bipolar voltages < or =0.1 mV were only found in patients with IART, and subsequently 0.1 mV was used as the cutoff value to delineate scar tissue. No unipolar cutoff value could be established. Timing of unipolar and bipolar local activation was correlated in all patient groups. CONCLUSIONS: The recording technique used has considerable impact on reconstruction of reentrant pathways and on the outcome of RFCA. In general, unipolar and bipolar recordings provide complementary information; however, only bipolar recordings allow voltage-based scar tissue delineation in patients with congenital heart disease.
Adult↗
Long-term follow-up after radiofrequency catheter ablation of ventricular tachycardia: a successful approach?
INTRODUCTION: Radiofrequency ablation (RFCA) of ventricular tachycardia (VT) is a potential curative treatment modality. We evaluated the results of RFCA in patients with VT. METHODS AND RESULTS: One hundred fifty-one consecutive patients (122 men and 29 women; age 57 +/- 16 years) with drug-refractory VT were treated. Underlying heart disease was ischemic heart disease in 89 (59%), arrhythmogenic right ventricular cardiomyopathy (ARVC) in 32 (21%), and idiopathic VT in 30 (20%; left ventricle in 9 [30%]; right ventricle in 21 [70%]). Ablation was performed using standard ablation techniques. Three hundred six different VTs were treated (cycle length 334 +/- 87 msec, 2.0 +/- 1.4 VTs per patient). Procedural success (noninducibility of VT after RFCA) was achieved in 126 (83%) patients (70 ischemic heart disease [79%]; 28 ARVC [88%]; 27 idiopathic VT [93%]). Procedure-related complications (< 48 hours) occurred in 11 (7%) patients: death 3 (2.0%), cerebrovascular accident 2 (1.3%), complete heart block 4 (2.6%), and pericardial effusion 3 (2.0%). Thirty-three (22%) patients received an implantable cardioverter defibrillator (because of hemodynamic unstable VT, failure of the procedure, or aborted sudden death). During follow-up (34 +/- 11 months), VT recurrences occurred in 38 (26%) patients (recurrence rate: 19% in successfully ablated patients and 64% in nonsuccessfully ablated patients; P < 0.001). During follow-up, 12 (8%) patients died (heart failure 8, unknown cause 1, noncardiac cause 3). CONCLUSION: RFCA of VT can be performed with a high degree of success (83%). The long-term outcome of successfully ablated patients is promising, with a 75% relative risk reduction compared with nonsuccessfully ablated patients. During follow-up, only one patient died suddenly, supporting a selective ICD placement approach in patients with hemodynamically stable VT.
Aged↗