V. Chauhan

Recommendations for the use of genetic testing in the clinical evaluation of inherited cardiac arrhythmias associated with sudden cardiac death: Canadian Cardiovascular Society/Canadian Heart Rhythm Society joint position paper.

The era of gene discovery and molecular medicine has had a significant impact on clinical practice. Knowledge of specific genetic findings causative for or associated with human disease may enhance diagnostic accuracy and influence treatment decisions. In cardiovascular disease, gene discovery for inherited arrhythmia syndromes has advanced most rapidly. The arrhythmia specialist is often confronted with the challenge of diagnosing and managing genetic arrhythmia syndromes. There is now a clear need for guidelines on the appropriate use of genetic testing for the most common genetic conditions associated with a risk of sudden cardiac death. This document represents the first ever published recommendations outlining the role of genetic testing in various clinical scenarios, the specific genes to be considered for testing, and the utility of test results in the management of patients and their families.

Electrogram fractionation in murine HL-1 atrial monolayer model

BACKGROUNDnComplex fractionated atrial electrograms have been suggested as important targets for catheter ablation of atrial fibrillation. The etiology and the mechanism of these signals have not been completely elucidated because of limitations of interpretation of these signals in relation to simultaneously acquired signals in the neighboring atrial tissue.nnnOBJECTIVEnThis study sought to study the origin of electrogram fractionation under the conditions of rotor formation and wave fragmentation, using atrial monolayer preparations.nnnMETHODSnWe performed optical mapping of 45 atrial monolayer preparations using a complementary metal oxide semiconductor (CMOS) Brainvision Ultima camera system (SciMedia-Brainvision, Tokyo, Japan).nnnRESULTSnWe observed stable rotors in 32 of the 45 recordings. The derived bipolar electrograms did not show complex fractionation at the core of the rotor in any of the 32 recordings. We were also able to show that 2 bipolar electrodes placed adjacent to the core of a stable rotor in a zone where there is no wave break will record electrical activity for the majority of the rotors cycle length. In 13 of the 45 recordings, wave break or wave collision events were present. Of these, 8 of 13 recordings showed complex fractionation. In 19 of the 27, simulation of meandering rotors also showed complex fractionation.nnnCONCLUSIONnComplex fractionated electrograms can be recorded at sites of migrating rotors and wave break. No fractionation occurs at the core of a stable rotor. Electrograms that span the rotor cycle length and alternate between 2 bipoles that straddle the core can identify site of a stable rotor.

Bipolar ablation for deep intra-myocardial circuits: human ex vivo development and in vivo experience.

AIMSnCurrent conventional ablation strategies for ventricular tachycardia (VT) aim to interrupt reentrant circuits by creating ablation lesions. However, the critical components of reentrant VT circuits may be located at deep intramural sites. We hypothesized that bipolar ablations would create deeper lesions than unipolar ablation in human hearts.nnnMETHODS AND RESULTSnAblation was performed on nine explanted human hearts at the time of transplantation. Following explant, the hearts were perfused by using a Langendorff perfusion setup. For bipolar ablation, the endocardial catheter was connected to the generator as the active electrode and the epicardial catheter as the return electrode. Unipolar ablation was performed at 50 W with irrigation of 25 mL/min, with temperature limit of 50°C. Bipolar ablation was performed with the same settings. Subsequently, in a patient with an incessant septal VT, catheters were positioned on the septum from both the ventricles and radiofrequency was delivered with 40 W. In the explanted hearts, there were a total of nine unipolar ablations and four bipolar ablations. The lesion depth was greater with bipolar ablation, 14.8 vs. 6.1 mm (P < 0.01), but the width was not different (9.8 vs. 7.8 mm). All bipolar lesions achieved transmurality in contrast to the unipolar ablations. In the patient with a septal focus, bipolar ablation resulted in termination of VT with no inducible VTs.nnnCONCLUSIONnBy using a bipolar ablation technique, we have demonstrated the creation of significantly deeper lesions without increasing the lesion width, compared with standard ablation. Further clinical trials are warranted to detail the risks of this technique.

Unusual intraatrial reentry following the Mustard procedure defined by multisite magnetic Electroanatomic mapping

SARDANA, R., et al.: Unusual Intraatrial Reentry Following the Mustard Procedure Defined by Multisite Magnetic Electroanatomic Mapping. This report describes a patient with d‐TGA post Mustard repair who presents with atrial arrhythmias. Two distinct intraatrial reentrant tachycardias were discovered and successful catheter ablation was performed in a unique atrial location not previously described. This case also explores the use of magnetic electroanatomic mapping in guiding catheter ablation. (PACE 2003; 26[Pt. I]:902–905)

Improved T-wave Alternans Detection in ECG Signals

T-wave alternans (TWA) is a pattern in electrocardiogram (ECG) signals characterized by two distinct forms of T-waves appearing in alternation, at a patient’s heart rate in the range of 90 to 120 beats per minute. There exists a relation between the amount of TWA, the heart rate at which it appears, and the risk of sudden cardiac death (SCD). Therefore, it is important to develop better methods to detect TWA in ECG signals. In this paper, we enhance an existing method for detecting TWA in ECG signals. Our proposed method reduces the noise in the ECG signals adaptively by using dual-tree complex wavelet transform (DTCWT). Our method for detecting TWA is based on the Matlab code of the champion (Jubair Sieed, Bangladesh University of Engineering and Technology) in the 2008 TWA challenge. Experimental results show that our proposed method outperforms three existing methods published on the TWA challenge website considerably in terms of Spearman rank correlation coefficient, Kendall rank correlation coefficient, root-mean-square-error (RMSE), and cross correlation (CC).