Catheter ablation of supraventricular tachycardia after tricuspid valve surgery in patients with congenital heart disease: A multicenter comparative study.

BACKGROUND: Tricuspid valve (TV) surgery is often required for adult congenital heart disease (ACHD), but may hinder catheter ablation when an artificial material or imbricated tissue covers the tricuspid annulus. OBJECTIVE: The purpose of this study was to determine the outcomes of catheter ablation after TV surgery in a large ACHD cohort. METHODS: An international retrospective study involving 7 centers was conducted. Patients who did and did not undergo TV surgery were matched for age, lesion classification, and postsurgical duration. TV operations were classified as valve ring/replacement vs repair. RESULTS: One hundred thirty-six patients (42 ring/replacement, 39 repair, and 55 no TV surgery; median 32 years [IQR 20 - 46]) underwent 180 procedures targeting 239 tachycardias (cavotricuspid-isthmus dependent intraatrial reentrant tachycardia 36%, other intraatrial reentrant tachycardia 29%, focal atrial tachycardia 18%, and other supraventricular tachyarrhythmia 17%). Post-TV surgery, procedures were longer (4.3 hours vs 3.3 hours; P = .003) and required longer fluoroscopy time (31 minutes vs 18 minutes; P = .001). At least partial acute success was achieved in 81% of procedures in the TV ring/replacement group vs 94% in both TV repair and no TV surgery groups (P = .03). The difference was driven mainly by ablation of annular substrates, with acute success in 73% of TV ring/replacement, 92% of TV repair, and 94% of no TV surgery groups (P = .01). Over a median of 3.0 years, tachycardia recurred after 26% of procedures. TV ring/replacement predicted recurrence in the multivariable analysis (hazard ratio 2.4; 95% confidence interval 1.2-5.2; P = .009). CONCLUSION: After surgery for ACHD, catheter ablation success was lower and tachycardia recurrence was higher after TV valve ring/replacement surgery. The findings of this retrospective report support future larger multicenter series and prospective evaluation to determine the role of empirical annular substrate ablation.

Imaging of Atrioventricular Nodal Conduction Tissue in Porcine Hearts Using Optical Coherence Tomography.

Optical coherence tomography (OCT) employs near-infrared light to image the microstructure of different tissues. Clinically, it has been used to image the walls of coronary arteries. In research settings, one of the applications for OCT is visualizing endocardial and subendocardial structures. The present experiment sought to determine whether OCT can identify native conduction tissues in adult porcine hearts. During the study, the right atrial endocardial surfaces of excised adult porcine hearts were exposed. The triangle of Koch was imaged with the OCT system and the conduction tissue was identified. The area was then prepared for histologic examination with Masson's trichrome stain. The results of histologic preparations and OCT images were then compared. Ultimately, nine porcine hearts were examined using this methodology. OCT imaging successfully identified subendocardial structures presumed to be the compact atrioventricular node. Histologic images of the preparations delineated the different tissue types and conduction tissue was easily identified. The location of distinctive hyporeflective areas in the OCT images correlated with the location of conduction tissue in the histology images. In light of the findings of this study, it is suggested that atrioventricular nodal tissue can be identified by OCT in freshly dissected unfixed porcine hearts. OCT images distinguished the differentiated conduction tissue in close proximity with the endocardium, myofibers, and fibrous tissue, and the success of this was verified with histology. This technology may be useful for the direct visualization of the native conduction system during procedures in the operating room and electrophysiology laboratory. Further studies with perfused tissue samples and live animal experiments are needed to better assess the efficacy of this novel application.

Confirm RX™ Cardiac Monitor Placement in a Pediatric Patient.

We present the first known report of a pediatric implantation of the Bluetooth™-enabled Confirm RX™ insertable cardiac monitor (Abbott Laboratories, Chicago, IL, USA) in a 17-year-old patient with unexplained syncopal episodes. This case illustrates the ability to obtain immediate rhythm information from a patient using a Bluetooth™-enabled device following a minimally invasive procedure.

Implantable cardioverter defibrillator implantation without using fluoroscopy in a pregnant patient.

Conventional lead implantation requires fluoroscopic guidance. This may be problematic in certain patient groups such as pregnant patients. We report a case of an implantable cardioverter defibrillator implantation without fluoroscopy in a pregnant patient.

Successful elimination of significant arrhythmia burden with flecainide in an adolescent with long QT syndrome type 3.

Congenital Long QT syndrome (LQTS) is a cardiac channelopathy, which leads to prolongation of the QT interval. This prolongation can lead to ventricular tachyarrhythmias, syncope, and sudden cardiac death. There are various types of LQTS associated with the mutations, which affect the genes coding the ion channels in the myocardial cells. Because of the differences in the ion channel physiology, clinical presentation of the subtypes can show significant differences. The most common types of LQTS are LQT1, LQT2, and LQT3. In LQT1 and LQT2, mutations are in the genes encoding Potassium channels (KCNQ1 and KCNH2 genes). These two subtypes show sensitivity to adrenergic stimuli. In LQT1, episodes are usually exercise-triggered, and in LQT2, episodes are more likely to be related to sudden arousal and emotional stress. Therefore treatment of LQT1 and LQT2 is mainly based on antiadrenergic therapy. LQT3 on the other hand, is a result of a mutation of SCN5A gene, which encodes the Sodium channels. In this type, patients are sensitive to vagal stimuli and episodes tend to occur at rest. Therefore, treatment choices between different subtypes of LQTS vary. In this case report, we report a patient with congenital LQT3 (Y1795C mutation) presenting with implantable cardioverter defibrillator (ICD) storm. Patient's arrhythmia burden was eliminated following successful treatment with flecainide.