Tissue tracking imaging as a new modality for identifying the origin of idiopathic ventricular arrhythmias

A new mapping method to estimate exit sites of ventricular arrhythmias using intracardiac echocardiography and M-mode for catheter ablation

Background

Catheter ablation of premature ventricular complexes (PVCs) has been used as a curative therapy in many cases. Intracardiac ultrasound with a magnetic sensor probe has recently become available for catheter ablation. In this study, we assessed a new mapping method, contraction mapping, for determining the optimal ablation sites using intracardiac ultrasound and M-mode. This study sought to assess the accuracy of the new mapping method using intracardiac echocardiography.

Methods

Eighteen patients (10 males and eight females; mean age, 63±12 years) with 104 mapping points diagnosed as idiopathic PVCs were included in this study. At the mapping points, the time interval from the onset of the QRS to the onset of the contraction (QRS-c-time) and the local activation time were measured using M-mode with an intracardiac echo probe and using the conventional method. The correlation between the QRS-c-time and local activation time were studied.

Results

The QRS-c-time was significantly correlated with the local activation time (activation time=−66.8+0.882 * QRS-c-time, R2=0.728, p<0.0001).

Conclusions

Contraction mapping could help determine the local activation time without the delivery of a catheter to the mapping points.

3D and 4D echo--applications in EP laboratory procedures

INTRODUCTION

3D echocardiography allows imaging and analysis of cardiovascular structures as they move in time and space, thus creating possibility for creation of 4D datasets (3D + time). Intracardiac echocardiography (ICE) further broadens the spectrum of echocardiographic techniques by allowing detailed imaging of intracardiac anatomy with 3D reconstructions. The paper reviews the current status of development of 3D and 4D echocardiography in electrophysiology. In ablation area, 3D echocardiography can enhance the performance of catheter ablation for complex arrhythmias such as atrial fibrillation. Currently, several strategies to obtain 3D reconstructions from ICE are available. One involves combination with electroanatomical mapping system; others create reconstruction from standard phased-array or single-element ICE catheter using special rotational or pull-back devices. Secondly, 3D echocardiography may be used for precise assessment of cardiac dyssynchrony before cardiac resynchronization therapy. Its reliable detection is expected to minimize number of non-responders to this treatment and optimize left ventricular lead positioning to get maximum hemodynamic benefit.

CONCLUSION

The main potential benefit of 3D and 4D echocardiography in electrophysiology lie in real-time guidance of complex ablation procedures and precise assessment of cardiac dyssynchrony.