Kim Rajappan

The impact of image integration on catheter ablation of atrial fibrillation using electroanatomic mapping: a prospective randomized study

AIMS A detailed appreciation of the left atrial/pulmonary venous (LA/PV) anatomy may be important in improving the safety and success of catheter ablation for AF. The aim of this randomized study was to determine the impact of computed tomographic (CT) integration into an electroanatomic mapping (EAM) system on clinical outcome in patients undergoing catheter ablation for atrial fibrillation (AF). METHODS AND RESULTS Eighty patients with AF were randomized to undergo first-time wide encirclement of ipsilateral PV pairs using EAM alone (40 patients) or with CT (40 patients, Cartomerge). Wide encirclement of the pulmonary veins was performed using irrigated radiofrequency ablation with the electrophysiological endpoint of electrical isolation (EI). The primary endpoint was single-procedure success at 6 month follow up. Acute and long-term procedural outcomes were also determined. There was no significant difference in single procedure success between EAM (56%) and cavotricuspid isthmus image (CTI) (50%) groups (P = 0.9). Acute procedural outcomes (EI, PV reconnection, sinus rhythm restored by ablation in persistent AF), fluoroscopy, and procedure durations (EI of right PVs, EI of left PVs, total) did not differ significantly between EAM and CTI groups. CONCLUSION Image integration to guide catheter ablation for AF did not significantly improve the clinical outcome. Achieving PV EI is the critical determinant of procedural success rather than the mapping tools used to achieve it.

Acute and Chronic Pulmonary Vein Reconnection after Atrial Fibrillation Ablation : A Prospective Characterization of Anatomical Sites

Background: Arrhythmia recurrence after atrial fibrillation (AF) ablation is often associated with pulmonary vein reconnection (PVR). We prospectively examined anatomical sites of both acute and chronic PVR.

Electrophysiologic and Anatomic Characterization of Sites Resistant to Electrical Isolation During Circumferential Pulmonary Vein Ablation for Atrial Fibrillation: A Prospective Study

Background: Catheter ablation (CA) by wide encirclement of pulmonary veins (WEPV) restores sinus rhythm in up to 95%. Complex PV–left atrial (LA) connections make achieving electrical isolation (EI) challenging. We examined anatomical and technical features associated with resistance to EI during WEPV in a prospective study.

Validation of Computed Tomography Image Integration into the EnSite NavX Mapping System to Perform Catheter Ablation of Atrial Fibrillation

Introduction: The complex anatomy of the left atrium (LA) makes location of ablation catheters difficult using fluoroscopy alone, and therefore 3D mapping systems are now routinely used. We describe the integration of a CT image into the EnSite NavX System with Fusion and its validation in patients undergoing atrial fibrillation (AF) or left atrial tachycardia (AT) catheter ablation.

Comparison of Techniques for the Measurement of Left Ventricular Function Following Cardiac Transplantation

BACKGROUND Assessment of graft function after cardiac transplantation is essential for patient management and clinical research. Previous studies have found that the left ventricular (LV) ejection fraction (EF) by echocardiography (echo), radionuclide ventriculography (RNV), and cardiovascular magnetic resonance (CMR) is discrepant in patients with heart failure. METHOD Twelve patients underwent LV EF assessment by echo, angiography (angio), RNV, and CMR one year following heart transplantation. The scans were analyzed independently in blinded fashion. RESULTS The mean EF was 63 +/- 6% by RNV, 66 +/- 6% by CMR, 70 +/- 12% by angio, and 74 +/- 4% by echo. Significant differences were found between CMR and echo (p < 0.001), RNV and echo (p < 0.001), and RNV and angio (p < 0.05). The correlation between the techniques was poor (r = 0.3-0.6), and the scatter plots also suggested considerable variations between techniques. This was confirmed by the wide Bland-Altman limits of agreement (ranging from 22 to 45%). These were particularly wide for comparisons with angiography (43-45%). CONCLUSION The EF measurement by echo, angio, RNV, and CMR are not interchangeable in patients following heart transplantation. The CMR and RNV provided the best agreement in EF and appear preferable for research studies. Echocardiography systematically overestimated LV EF and showed poor agreement with other techniques. Angiography overestimated LV function, and its routine use did not add to information gained from noninvasive studies.

Left ventricular quantification in heart failure by cardiovascular MR using prospective respiratory navigator gating: Comparison with breath‐hold acquisition

Cardiovascular magnetic resonance (CMR) is the reference standard for the assessment of cardiac function. Faster sequences, such as breath‐hold (BH) fast low‐angle shot, have made CMR more clinically acceptable and cost effective. In a significantly large patient group, however, holding their breath is difficult, resulting in poor‐quality images. We compared prospective navigator‐echo respiratory gating (NE), which allows image acquisition during free breathing, and BH imaging in 14 patients with heart failure and 10 normal volunteers. There was good agreement between both NE and BH volumes, mass, and ejection fraction. The image quality of both NE basal and apical slices was significantly better than the corresponding BH slices in both the heart failure (P < 0.01) and normal groups (P < 0.05). The NE image acquisition was more time efficient than the BH acquisition in the heart failure group (P < 0.01), with no difference in the normal group (P = 0.2). Thus, prospective navigator‐echo gating, previously only described in coronary artery imaging, can be used in the assessment of cardiac function. It is particularly useful in patients who find it difficult to hold their breath in whom NE provides good‐quality, time‐efficient images. J. Magn. Reson. Imaging 2000;11:411–417.

Development of a technique for left ventricular endocardial pacing via puncture of the interventricular septum.

Background—Left ventricular (LV) pacing through the coronary sinus is the standard approach for cardiac resynchronization therapy. When this route is unavailable, the alternatives have major limitations. LV endocardial pacing through the interventriuclar septum may offer a simpler solution. We describe an initial case series to demonstrate technical feasibility and to describe our refinement of the puncture technique. Methods and Results—Ten patients with previous failed coronary sinus lead implant or with nonresponse to cardiac resynchronization therapy and a suboptimal LV lead position were selected. All patients were anticoagulated. Left ventriculography and coronary angiography were performed to identify LV borders and septal vessels. Subclavian vein access was used for a superior approach ventricular transseptal puncture under fluoroscopic guidance, using a steerable sheath and a standard transseptal needle, radiofrequency needle, or radiofrequency energy delivered through a guidewire. An active-fixation pacing lead was successfully delivered to the endocardial wall of the lateral LV in all patients (9 men; age, 62±10 years). LV lead implant procedure time shortened with experience. The use of radiofrequency energy delivered through a guidewire was the most effective technique. Mean threshold and R wave at implant were 0.8±0.3 V and 10.8±3.9 mV. At follow-up (mean, 8.7 months; minimum, 0; and maximum 19), thresholds were stable, and there were no thromboembolic events. Of 9 patients, 8 were classed as clinical responders (1 had inadequate follow-up to assess response). Conclusions—LV endocardial pacing through a ventricular septal puncture is a feasible approach for cardiac resynchronization therapy.

Infarct zone viability influences ventricular remodelling after late recanalisation of an occluded infarct related artery

Objective: To investigate the influence of infarct zone viability on remodelling after late recanalisation of an occluded infarct related artery. Methods: A subgroup of 26 volunteers from TOAT (the open artery trial) underwent dobutamine stress cardiovascular magnetic resonance at baseline to assess the amount of viable myocardium present with follow up to assess remodelling at one year. TOAT studied patients with left ventricular dysfunction after anterior myocardial infarction (MI) associated with isolated proximal occlusion of the left anterior descending coronary artery with randomisation to percutaneous coronary intervention (PCI) with stent at 3.6 weeks after MI (PCI group) or to medical treatment alone (medical group). Results: In the PCI group there was a significant relation between the number of viable segments within the infarct zone and improvement in end systolic volume index (−7.7 ml/m2, p  =  0.02) and increased ejection fraction (4.1%, p  =  0.03). The relation between viability and improvements in end diastolic volume index (−8.8 ml/m2, p  =  0.08) and mass index (−6.3 g/m2, p  =  0.01) did not reach significance (p  =  0.27 and p  =  0.8, respectively). In the medical group, there was no significant relation between the number of viable segments in the infarct zone and the subsequent changes in end diastolic (p  =  0.84) and end systolic volume indices (p  =  0.34), ejection fraction (p  =  0.1), and mass index (p  =  0.24). Conclusion: The extent of viable myocardium in the infarct zone is related to improvements in left ventricular remodelling in patients who undergo late recanalisation of an occluded infarct related artery.

A randomized trial to compare atrial fibrillation ablation using a steerable vs. a non-steerable sheath

AIMS Catheter positioning and stability are recognized challenges in catheter ablation of atrial fibrillation (AF). This prospective randomized study assessed whether routinely using a steerable sheath affects procedure outcomes. METHODS AND RESULTS Fifty-six AF patients were randomized to ablation using either an Agilis NXT (St Jude Medical, St Paul, MN, USA) steerable sheath or a fixed-curve Mullins sheath (Cook Medical Inc., Bloomington, IN, USA) for the ablation catheter. A mapping system with CT integration was used to isolate the pulmonary veins (PVs) in pairs and further ablation performed if AF persisted. There was no significant difference in time to gain trans-septal access, CT registration time, time to isolate PVs, fluoroscopy time for PV isolation, total procedure time, or total fluoroscopy time. A learning curve was seen for the steerable sheath, and after correcting for this, CT registration time and right PV isolation were quicker in this group. One patient crossed over from fixed-curve to steerable. Acute, 3-, and 6-month single procedure success were similar in both groups. CONCLUSION Allowing for the usage learning curve, a steerable sheath reduced time for some elements of AF ablation. Although this did not result in improved success, it may be useful for inexperienced operators, but at increased procedure cost.

Balloon occlusion of the distal coronary sinus facilitates mitral isthmus ablation

BACKGROUND Mitral isthmus ablation is challenging. Blood flow in the coronary sinus (CS) may act as a heat sink and reduce the efficacy of radiofrequency ablation. OBJECTIVE This study investigates whether balloon occlusion of CS facilitates mitral isthmus ablation. METHODS This single-center, prospective, randomized controlled trial included patients undergoing ablation for atrial fibrillation. After circumferential pulmonary vein isolation and roof line ablation, mitral isthmus ablation was performed during left atrial appendage pacing using an irrigated ablation catheter (endocardium: maximum power: 40/50 W, maximum temperature: 48°C; CS: maximum power: 25/30 W, maximum temperature: 48°C). An air-filled 40 × 10-mm percutaneous transluminal angioplasty balloon (Opta Pro, Cordis Europa, LJ Roden, The Netherlands) was used to occlude the CS on the epicardial aspect of the ablation line. Left coronary and CS angiography were performed before and after the procedure. RESULTS Forty-six patients were studied. The balloon was successfully positioned in the distal CS in 20 of 23 patients (87%). Mitral isthmus block was achieved in 41 of 46 patients (91%). According to intention-to-treat analysis, there was significant reduction in the need for epicardial CS ablation (48% vs. 83%, P = .01) in the CS occlusion group but no difference in acute success rate. Secondary analysis showed reduction in mean total ablation time (9.4 ± 5.5 vs. 13.3 ± 4.6 minutes, P <.02) and mean CS ablation time (1.5 ± 2.8 vs. 3.4 ± 2.7 minutes, P <.05) in patients who had CS occlusion. CONCLUSION Balloon occlusion of the CS during mitral isthmus ablation is feasible and safe. It significantly reduces ablation time and the need for CS ablation to achieve mitral isthmus block. The results support the hypothesis that heat sink is one of the obstacles to successful mitral isthmus ablation.