Toward magnetic resonance-guided electroanatomical voltage mapping for catheter ablation of scar-related ventricular tachycardia: a comparison of registration methods

Toward MR‐Guided Electroanatomical Voltage Mapping for Catheter Ablation. Introduction: Integration of preprocedural delayed enhanced magnetic resonance imaging (DE‐MRI) with electroanatomical voltage mapping (EAVM) may provide additional high‐resolution substrate information for catheter ablation of scar‐related ventricular tachycardias (VT). Accurate and fast image integration of DE‐MRI with EAVM is desirable for MR‐guided ablation. Methods and Results: Twenty‐six VT patients with large transmural scar underwent catheter ablation and preprocedural DE‐MRI. With different registration models and EAVM input, 3 image integration methods were evaluated and compared to the commercial registration module CartoMerge. The performance was evaluated both in terms of distance measure that describes surface matching, and correlation measure that describes actual scar correspondence. Compared to CartoMerge, the method that uses the translation‐and‐rotation model and high‐density EAVM input resulted in a registration error of 4.32±0.69 mm as compared to 4.84 ± 1.07 (P <0.05); the method that uses the translation model and high‐density EAVM input resulted in a registration error of 4.60 ± 0.65 mm (P = NS); and the method that uses the translation model and a single anatomical landmark input resulted in a registration error of 6.58 ± 1.63 mm (P < 0.05). No significant difference in scar correlation was observed between all 3 methods and CartoMerge (P = NS). Conclusions: During VT ablation procedures, accurate integration of EAVM and DE‐MRI can be achieved using a translation registration model and a single anatomical landmark. This model allows for image integration in minimal mapping time and is likely to reduce fluoroscopy time and increase procedure efficacy. (J Cardiovasc Electrophysiol, Vol. 23, pp. 74‐80, January 2012)     

中国汉族单纯型发作性运动诱发性运动障碍家系的致病基因定位研究

目的 在1个中国汉族单纯型发作性运动诱发性运动障碍(paroxyamal kinesigenic dykinesia,PKD)大家系中定位其致病基因所在区域.方法 用商业化的ABI微卫星试剂盒进行全基因组扫描,用Linkage和Genehunter等软件对基因分型的结果 进行参数和非参数连锁分析,并在最可能的阳性区域内进一步选择微卫星位点进行精细定位和单倍型分析.验证全基因组扫描结果 并缩小单纯型PKD家系的新位点区域.结果 全基因组扫描在D3S1580处得到最大的两点LOD值1.75(θ=0);精细定位在D3S3669处得到最大的LOD值2.82(θ=0),NPL值9.83.单倍型分析将致病基因定位于D3S1314和D3S1265之间约10.2 cM大小的区域.结论 该单纯型PKD家系的致病基因定位于3q28-29的D3S1314和D3S1265之间10.2 cM区域,是一个新的PKD致病基因位点.     

New strategies for ventricular tachycardia and ventricular fibrillation ablation

Patients with ventricular tachycardia (VT) and ventricular fibrillation (VF) and no reversible cause are difficult to treat. While implantable defibrillators prolong survival, many patients remain symptomatic due to device shocks and syncope. To address this, there have been recent advances in the catheter ablation of VT and VF. For example, non-invasive imaging has improved arrhythmia substrate characterisation, 3D catheter navigation tools have facilitated mapping of arrhythmia and substrate and ablation catheters have advanced in their ability to deliver effective lesions. However, the long-term success rates of ablation for VT and VF remain modest, with nearly half of treated patients developing recurrence within 2–3 years, and this drives the ongoing innovation in the field. This review focuses on the challenges particular to ablation of life-threatening ventricular arrhythmia, and the strategies that have been recently developed to improve procedural efficacy. Patient sub-groups that illustrate the use of new strategies are described.     

Imaging techniques in cardiac electrophysiology

Modern cardiac electrophysiology procedures include catheter-based arrhythmia ablation and transvenous device implantation, which are highly dependent on accurate, real-time cardiac imaging. With the realization that anatomic structures are critical to successful electrophysiologic procedures, accurately defining a patient’s cardiac anatomy has become more important. Fluoroscopy allows for 2D imaging of cardiac structures in real-time, and is used to guide catheter and lead placement, but does not allow for visualization of soft tissues. Intracardiac echocardiography allows for both direct visualization of anatomic structures within the heart and real-time imaging during catheter placement. Despite advances in intracardiac echocardiography catheters that allow for larger windows, the ability to accurately delineate anatomic structures depends on the patient’s anatomy and operator experience. Neither of these techniques allows for electrical mapping of the heart; however, both anatomic and electrical intracardiac mapping can be achieved with advanced mapping systems. These systems allow for real-time catheter localization, help elucidate cardiac anatomy, evaluate electrical activation during arrhythmias and guide catheter placement for deliverance of radiofrequency current. More recently, 3D cardiac computed tomography has been used to accurately define intracardiac anatomy; however, catheter tracking and electrical mapping cannot be performed by computed tomography. Mapping systems are now being merged with computed tomography images to produce an accurate anatomic and electrical map of the heart to guide catheter ablations. The objective of this paper is to describe the current imaging and mapping techniques used in electrophysiologic procedures.     

Accuracy of circulating cathodic antigen tests for rapid mapping of Schistosoma mansoni and S. haematobium infections in Southern Sudan

Objective To evaluate the diagnostic accuracy of a circulating cathodic antigen (CCA) urine dipstick test for detecting Schistosoma mansoni and S. haematobium alongside an integrated rapid mapping survey in Southern Sudan. Methods and Results A total of 373 children aged 5–16 years were included in the study. Of these 26.0% were infected with S. haematobium and 24.5% were infected with S. mansoni, as identified by urine filtration or single Kato–Katz thick smear, respectively. The CCA performed moderately in detecting S. mansoni, with sensitivity of 89.1% and specificity of 74.2%, and poorly in detecting S. haematobium infections, with a sensitivity of 36.8% and specificity of 78.9%. This may be a slight underestimate of true CCA accuracy, since only single stool and urine samples were examined by microscopy. The true ‘gold standard’ for comparison would have been the collection of multiple stool samples over consecutive days. Conclusion The poor CCA accuracy for diagnosis of urinary schistosomiasis means that this test is currently not suitable for rapid mapping of schistosomiasis in areas where both S. mansoni and S. haematobium may be endemic.     

In vivo detection of striatal dopamine release during reward: a PET study with [(11)C]raclopride and a single dynamic scan approach

A new simple method is proposed to detect, using PET and [(11)C]raclopride, changes in striatal extracellular dopamine concentration during a rewarded effortful task. This approach aimed to increase the sensitivity in detection of these effects. It requires a single-dynamic PET study and combines the classic kinetic compartmental model with the general linear model of SPM to provide statistical inference on changes in [(11)C]raclopride time-activity curve due to endogenous dopamine release during two short periods of activation. Kinetic simulations predicted that 100% dopamine increase during two 5-min periods starting at 30 and 60 min after the injection can be detected. Moreover the effects of dopamine release on the [(11)C]raclopride time-activity-curve are different from those induced by CBF increase. These simulated curves were used to construct the statistical linear model and to test voxel-by-voxel in healthy subjects the hypothesis that dopamine is released in the ventral striatum during periods of unexpected monetary gains, but not during periods of unexpected monetary loss. The experimental results are in line with the expected results although the amplitude of the effects due to dopamine release is moderate. The advantages and the limits of this method as well as the relevance of the results for dopamine involvement in reward processing are discussed.