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Articles by V Castro
Total Records ( 2 ) for V Castro
  A Kolandaivelu , M. M Zviman , V Castro , A. C Lardo , R. D Berger and H. R. Halperin

Failure to achieve properly localized, permanent tissue destruction is a common cause of arrhythmia recurrence after cardiac ablation. Current methods of assessing lesion size and location during cardiac radiofrequency ablation are unreliable or not suited for repeated assessment during the procedure. MRI thermography could be used to delineate permanent ablation lesions because tissue heating above 50°C is the cause of permanent tissue destruction during radiofrequency ablation. However, image artifacts caused by cardiac motion, the ablation electrode, and radiofrequency ablation currently pose a challenge to MRI thermography in the heart. In the current study, we sought to demonstrate the feasibility of MRI thermography during cardiac ablation.

Methods and Results—

An MRI-compatible electrophysiology catheter and filtered radiofrequency ablation system was used to perform ablation in the left ventricle of 6 mongrel dogs in a 1.5-T MRI system. Fast gradient-echo imaging was performed before and during radiofrequency ablation, and thermography images were derived from the preheating and postheating images. Lesion extent by thermography was within 20% of the gross pathology lesion.


MR thermography appears to be a promising technique for monitoring lesion formation and may allow for more accurate placement and titration of ablation, possibly reducing arrhythmia recurrences.

  J Toquero , J Alzueta , L Mont , I. F Lozano , A Barrera , A Berruezo , V Castro , J. L Pena , M. L Fidalgo and J. Brugada

Implantable cardioverter defibrillators (ICDs) are increasingly being used for treatment of ventricular tachycardia (VT)/fibrillation. Inappropriate therapy delivery remains the most frequent complication in patients with ICDs, resulting in psychological distress, proarrhythmia, and battery life reduction. We aim to determine if inappropriate therapies could be reduced by using a morphology discrimination criterion.

Methods and results

We evaluated the performance of the WaveletTM morphology discrimination algorithm (Medtronic, Inc.) independently from other discrimination enhancements (rate onset and interval stability). A non-randomized, prospective, multicenter, and observational study was designed to determine the sensitivity and specificity of the new morphology criterion. Sensitivity and specificity in slow tachycardia with cycle length (CL) between 340 and 500 ms were analysed as a pre-specified secondary endpoint. A total of 771 spontaneous episodes in 106 patients were analysed. Five hundred and twenty-two episodes corresponded to true supraventricular tachycardia (SVT) with ventricular CL in the VT or FVT zone, of which 473 had therapy appropriately withheld. Of the 249 episodes of true VT/FVT, 21 were classified according to the WaveletTM criteria as SVT (specificity: 90.6%; sensitivity: 91.6%). All of them were spontaneously terminated with no adverse clinical consequences. No syncopal episodes occurred. For VTs in the slowest analysed range (CL: 340–500 ms), a total of 235 episodes were studied, yielding a specificity of 95.9% and sensitivity of 83.2%.


WaveletTM discrimination criteria in single-chamber ICDs as the sole discriminator can significantly reduce inappropriate therapy for SVT, not only in the range of VTs in the slowest analysed range (340–500 ms for this study) but also for faster VTs. No significant clinical consequences were found when the algorithm was used, but final data should prompt the use of the algorithm in combination with a high rate time-out feature.

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