Ablation of nonsustained or hemodynamically unstable ventricular arrhythmia originating from the right ventricular outflow tract guided by noncontact mapping

Conventional activation or pacemapping is effective in guiding ablation of ventricular tachyarrhythmia originating from right ventricular outflow tract (RVOT). However, in selected patients with hemodynamically unstable or nonsustained tachycardia, noncontact mapping may be an effective alternative method to guide ablation in RVOT. Five patients with symptomatic hypotension during ventricular tachycardia (VT) or nonsustained tachyarrhythmia originating from the RVOT had radiofrequency ablation guided by noncontact mapping. All patients had a history of syncope and the tachyarrhythmias were refractory to antiarrhythmic therapy. Four patients had spontaneous sustained VT of a cycle length from 250 to 300 ms and one had symptomatic ventricular ectopic beats. Two patients were diagnosed to have arrhythmogenic right ventricular cardiomyopathy (ARVC). Sustained VT with hypotension was induced in two patients and nonsustained VT in three patients. Isopotential color maps were used to locate the earliest activation site of the tachyarrhythmia in RVOT. Three patients had tachyarrhythmia exit sites at the septal region and two at lateral region of RVOT. Low voltage area and diastolic activity were detected in the two patients with ARVC. Radiofrequency ablation guided by noncontact mapping was performed during sinus rhythm in all patients. The number of ablation attempts ranged from 1 to 14. After follow-up for 12 +/- 5.8 months, there was no recurrence of tachyarrhythmia and syncope in all five patients. Noncontact mapping is a safe and effective alternative method to guide ablation of hemodynamically unstable or nonsustained ventricular arrhythmia originating from RVOT.     

An atypical atrial flutter of focal origin: a study using a noncontact mapping system

We report a case of focal atrial tachycardia with appearance suggestive of atypical atrial flutter in a 57-year-old man. Based on ECG criteria, tachycardia was misclassified as atypical atrial flutter. The electrophysiological study using a noncontact mapping system revealed a focal activity within the left upper pulmonary vein ostium. This case highlights the limitations of standard electrocardiographic and electrophysiological classifications of regular atrial tachycardia. This report also shows the relevance of new mapping techniques in the successful mapping and ablation of these arrhythmias, even those arising within the left atrium.     

Use of advanced mapping systems to guide ablation in complex cases: experience with noncontact mapping and electroanatomic mapping systems

OBJECTIVE: This report describes our experience with noncontact mapping and electroanatomic mapping in complex ablations, which are defined as ablations done after failure of conventional ablation. MATERIAL AND METHODS: Patients were included (N = 68; 49% with structural heart disease) in whom previous ablation failed and in whom a second procedure was done with advanced mapping. Non-contact mapping was used in 17 patients, electroanatomic mapping in 36, and both noncontact and electroanatomic mapping in 15. Arrhythmias included focal atrial tachycardia (n = 16), reentrant atrial tachycardia (n = 14), right ventricular outflow tachycardia (n = 10), post-myocardial infarction ventricular tachycardia (n = 9), and others (n = 19). RESULTS: Acute success at the second ablation was achieved in 79% of patients. At 20 +/- 9 months after the procedure, 69% of these patients reported having significantly fewer symptoms than before the second ablation, and 51% were free of symptoms. Only 16% were using antiarrhythmic medications. Complications included a small pericardial effusion in two patients, hypotension in one patient, and a femoral pseudoaneurysm in another. CONCLUSIONS: Advanced mapping is a useful and safe adjunct for catheter ablation after ablation has failed in patients with complex substrate.     

Influence of high-pass filtering on noncontact mapping and ablation of atrial tachycardias

The aim of the study was to define the impact of different high-pass filter settings (HPF) on the accuracy of mapping of ectopic atrial tachycardias (EAT) using a noncontact mapping (NCM) system. In 20 patients with 22 EAT a noncontact probe was deployed in the right (n = 19) or in the left atrium (n = 3). The device enables interpolation and analysis of unipolar electrograms. It provides information on focus localization and signal morphology. These parameters were compared in different HPF of 0.5 Hz, 2 Hz, 8 Hz, and 16 Hz. The NCM signal morphology was preserved at all HPF. An initial negative deflection recorded by NCM system showed a positive predictive value of 93% regarding the ablation success. The deviation (spatial disparity) between visualized focus origin and successful ablation site was 6.9 +/- 5.4 mm. Between two consecutive filter settings, the focus shift was more pronounced between 0.5 and 2 Hz (5.4 +/- 4.5 mm) compared to a setting between 8 and 16 Hz (2.9 +/- 2.9 mm; P < 0.05). Successful ablation was achieved in 15/18 right atrial tachycardias (83%) and in 2/3 left atrial arrhythmias. Different HPF influence NCM spatial analysis of EAT. However, a small variability in foci localization does not impact final ablation results.     

Multiple distinct right atrial endocardial origins in a patient with atrial tachycardia: mapping and ablation using noncontact mapping

Noncontact mapping identified the endocardial origins of four distinct atrial tachycardias in a young patient with drug refractory palpitations and effected successful ablation with no recurrence of symptoms in 5 months of follow-up.     

Electroanatomic mapping of endocardial right ventricular activation as a guide for catheter ablation in patients with arrhythmogenic right ventricular dysplasia

Arrhythmogenic right ventricular dysplasia is a structural heart disease characterized by fibrofatty degeneration of right ventricular myocardium and arrhythmias of right ventricular origin. The aim of this study was to characterize endocardial right ventricular activation by electroanatomic mapping as a guide for catheter ablation in patients with arrhythmogenic right ventricular dysplasia. Electroanatomic mapping and entrainment procedures were performed in 5 patients with arrhythmogenic right ventricular dysplasia. Endocardial mapping during ventricular tachycardia demonstrated a focal activation pattern with radial spreading of activation from a site of earliest ventricular activation in all directions. Right ventricular activation time (127 +/- 34 ms) was markedly shorter than tachycardia cycle length (415 +/- 92 ms). The site of earliest ventricular activation was found in an aneurysmal outflow tract (n = 2), at the border of aneurysms near the tricuspid annulus (n = 2), and at the apex of the right ventricle (n = 1). Entrainment mapping criteria of these areas of earliest endocardial activity were consistent with exit sites of a reentrant circuit in an area of abnormal myocardium. Fractionated potentials were found 61 +/- 29 ms before the onset of the QRS complex at these sites. Catheter ablation rendered the "clinical" ventricular tachycardia noninducible in four patients but "nonclinical" faster ventricular tachycardias were inducible in three patients. During the follow-up of 7 +/- 3 months after ablation, the frequency of therapies in 4 patients with an implantable cardioverter defibrillator decreased from 49 +/- 61 episodes per month before ablation, to 0.3 +/- 0.5 episodes per month after ablation (P < 0.05). Electroanatomic mapping during ventricular tachycardia facilitates localization of exit sites in relation to aneurysms in diseased right ventricle and may guide catheter ablation in patients with arrhythmogenic right ventricular dysplasia.     

Diagnosis and ablation of atrial flutter using a high resolution, noncontact mapping system

The ablation of atrial flutter can sometimes be time consuming and unsuccessful using conventional catheter techniques especially in patients with recurrences after previous ablation procedures. Simultaneous high resolution mapping from multiple sites may overcome some of the limitations. Therefore, a new high resolution noncontact mapping system was used for diagnosis and ablation of atrial flutter in 15 patients. The mapping system consists of a catheter-mounted multielectrode array, an amplifier, and a computer workstation. Far-field potentials recorded by the multielectrode catheter are amplified, digitized, and sampled at 1.2 kHz, and digitally filtered to construct high resolution activation maps during tachycardia. Ablation catheters can be steered to target sites without fluoroscopy. In 12 of the 15 patients the analysis of the activation sequence during tachycardia showed a counter-clockwise, and in 1 of 15 patients a clockwise, rotating wavefront using the isthmus as part of the reentrant circuit. In two patients no tachycardia could be induced. In 3 of the 15 patients with previous conventional ablation procedures the gap in the line of block in the isthmus region was identified and marked on the animation model. The isthmus in the right atrium was ablated and isthmus block verified by the mapping system in all patients. No complications were observed. No recurrences of atrial flutter occurred during follow-up of 4 +/- 1.7 months. The total procedure and fluoroscopy time was 171 +/- 50.0 minutes and 24 +/- 12.7 minutes, respectively. In conclusion, the use of the new high resolution noncontact mapping system in patients with right atrial flutter is safe and highly effective. In patients with previously failed conventional ablation procedures the use of a noncontact mapping system may facilitate the identification of the gap in the line of block in the isthmus region and reablation of atrial flutter.     

Combined left and right ventricular volume determination by radionuclide angiocardiography using double bolus and equilibrium technique

Summary. Eighteen patients with ischaemic heart disease were studied. Left and right ventricular volumes including cardiac output (forward flow) were determined by radionuclide angiocardiography using a double bolus and equilibrium technique. As reference, cardiac output was simultaneously measured by indicator dilution. The radionuclide technique comprised four steps:

• 1 a first-pass study of right ventricle;
• 2 a bolus study of left ventricle;
• 3 an equilibrium study of left ventricle;
• 4 determination of the distribution volume of red blood cells.

Absolute volumes of left ventricle were determined from steps 2+3+4. Absolute volumes of right ventricle were calculated from stroke volume and right ventricular ejection fraction (EF) which in turn was determined from step 1 by creating composite systolic and composite diastolic images. There was an acceptable agreement between stroke volume determinations by radionuclide angiocardiography and indicator dilution (r= 0.74; P<0.001). Stroke volume determination by radionuclide was 83±20 ml (mean±SD) and by indicator dilution 84±20 ml with a difference of -1±15 ml (NS). Cardiac output determination by radionuclide was 5.24±1.37 1 min^-1 and by indicator dilution 5.28±1.23 1 min^-1 with a difference of -0.04±0.95 1 min^-1 (NS). Left ventricular EF was 0.44 ±0.14 and right ventricular EF 0.57 ±0.10. The intra-observer coefficient of variation for duplicate calculations of the radionuclide determinations was 5.5% for stroke volume, 2.5% for left ventricular EF and 4–8% for right ventricular EF.     

血流向量成像技术评价右心室心尖起搏对左心室流场分布的影响

目的 应用血流向量成像（VFM）技术显示左心室腔内的血液流场,探讨右心室心尖起搏状态下左心室腔内流场变化规律。方法 选取14例因病态窦房结综合征植入双腔起搏器的患者（起搏组）及30例正常人（对照组）为观察对象,使用DAS-RS1软件获取左心室腔VFM涡流图像,测量等容收缩期与舒张中期主涡流的直径（横径Dx、纵径Dy）、涡流位置（横向Px、纵向Py）、涡流圈数、涡流中心数目、涡流最大向量速度（Vmax）及涡流持续时间。结果 右心室心尖起搏组与对照组比较,等容收缩期和舒张中期左心室腔内主涡流直径变小,涡流圈数减少,涡流中心数目增加,最大向量速度减慢,涡流持续时间延长（P＜0.05）。结论 VFM技术能直观显示、定量分析右心室心尖部起搏状态下左心室腔内流场分布。     

Arrhythmogenic difference between the left and right atria in a canine ventricular pacing-induced heart failure model of atrial fibrillation

Background: The detail of biatrial activation during sustained atrial fibrillation (AF) has not been investigated until now. Methods: Five dogs with right ventricular pacing‐induced congestive heart failure (CHF) and five normal dogs were included. Biatrial endocardiac mapping was performed using noncontact mapping system. Results: Noncontact mapping of the right atrium (RA) showed CHF dogs had a higher frequency of focal discharge from Bachmann's bundle, sinoatrial region, and crista terminalis. CHF dogs also had a higher frequency of wave break, wave fusion, and reentry. CHF dogs had greater effective refractory period (ERP) dispersion. Noncontact mapping of the left atrium (LA) showed CHF dogs had more frequent focal discharge from left superior pulmonary vein (PV), right superior PV, and left atrial appendage. CHF dogs had a higher frequency of wave break, wave fusion, and reentry. CHF dogs had greater ERP dispersion. Comparison between RA and LA showed LA had a higher frequency of focal discharge, wave break, wave fusion, and leading circle reentry than the RA. LA also had greater ERP dispersion than RA. Conclusion: CHF dogs had a higher frequency of focal discharge and reentry, suggesting that CHF provided an arrhythmogenic substrate. LA had a higher frequency of focal discharge and reentry, suggesting that LA is more important to maintain AF. (PACE 2012; 35:188–195)     

Use of complex fractionated atrial electrogram mapping system in mapping and ablating the atrial flutter of a transplanted heart

Atrial flutter in donor part of orthotopic heart transplant has been reported and treated by radiofrequency ablation in the past. Complex fractionated atrial electrogram (CFE) mapping has been used to simplify the ablation of chronic atrial fibrillation. Here, we report a case with atrial flutter in an orthotopic heart transplant whose circuit mapping was difficult. Using CFE helped us to define the arrhythmia circuit easily and perform curative ablation.     

Cardiac MRI: accuracy of simultaneous measurement of left and right ventricular parameters using three different sequences

BACKGROUND AND AIM: We evaluated a value of Qp/Qs (left-to-right shunt measurement) using volumetric cardiac magnetic resonance (CMR) cardiac output (CO) measurements. We defined intraobserver, interobserver variability and reproducibility of left and right ventricular parameters by CMR. Furthermore, we studied whether shortened acquisition time has an effect on the accuracy of left and right ventricular parameters both in healthy volunteers and in patients with cardiovascular disease. METHODS: Sixteen subjects were enrolled in this study. Group A (n = 8, five males) consisted of healthy volunteers with a mean age of 25.9 years (range 24-30). Group B (n = 8, four males) was heterogenic consisting of patients with left ventricular (LV) hypertrophy, hypertension or coronary artery disease with their mean age of 56.3 years (range 38-70). RESULTS: The measured Qp/Qs as calculated from the right and LV CO was 0.87 +/- 0.13. Overall variability [as presented with the lowest coefficient of variation (CV)%- the highest CV % of intraobserver, interobserver variability or reproducibility] of LV parameters were for ejection fraction (EF) 1.5-2.8%, stroke volume (SV) 1.3-3.2%, CO 1.4-3.2%, end-diastolic volume 0.5-3.0%, end-systolic volume 1.8-6.2% and LV mass 1.1-2.6%. Corresponding values for right ventricular parameters were for EF 1.1-4.2%, SV 1.9-8.2%, CO 1.9-7.6%, end-diastolic volume 2.1-7.6%, end-systolic volume 2.8-10.2% and right ventricle mass 2.9-8.3%. There was no statistically significant difference between the results of different sequences. CONCLUSIONS: The CMR allows accurate Qp/Qs observation but the absolute value is at slightly different level compared with reference methods. Both left and right ventricular parameters are highly reproducible and even small clinically relevant changes can be measured with CMR. The shortened acquisition does not affect significantly to the accuracy of CMR-derived parameters.     

Implantation of left ventricular leads using a telescopic catheter system

BACKGROUND: Implantation procedures for cardiac resynchronization therapy (CRT) remain challenging with regard to coronary sinus (CS) cannulation and left ventricular (LV) lead positioning. Technologic advances in catheter design may facilitate CS cannulation and LV lead placement. AIMS: To evaluate two different telescoping dual-catheter systems, RAPIDO Guiding Catheter System (Group R) and RAPIDO ADVANCE Guiding Catheter System (Group A) (Guidant Inc., St. Paul, MN, USA), during implantation of a CRT device. METHODS: Seventy-four consecutive patients randomly received a CRT device using the R or A system. RESULTS: An LV lead was successfully implanted in 74 patients (100%). (1) Median times for CS cannulation in groups R and A were 0.3 minutes (range from 0.05 to 14 minutes) and 0.5 minutes (range from 0.05 to 9 minutes), respectively (P = NS). (2) Median times for LV lead placement were 8 minutes (range from 0.8 to 100 minutes) and 3.5 minutes (range from 0.25 to 30 minutes), respectively, for groups R and A (P = 0.032). (3) Median total fluoroscopy times were 12.33 minutes (range from 5 to 70 minutes) and 14.33 minutes (range from 6 to 53 minutes) for groups R and A, respectively (P = NS). (4) Median procedural times for CRT implantation were 80 minutes (range from 40 to 200 minutes) and 75 minutes (range from 45 to 180 minutes) (P = NS) in groups R and A, respectively. There were no major complications. CONCLUSION: CS cannulation and LV lead placement with a telescopic dual-catheter system is a safe and feasible approach that may reduce fluoroscopy and overall CRT implantation times. Our observations suggest that the RAPIDO ADVANCE System is faster than the RAPIDO System in terms of median time for LV lead positioning.     

Ablation of incisional atrial tachycardias using a three-dimensional nonfluoroscopic mapping system

Incisional atrial reentrant tachycardias are macroreentrant arrhythmias in which surgical scars or prosthetic material constitute one of the constraining barriers of the circuit. Accurate reconstruction based on fluoroscopy-guided endocardial mapping of the reentrant circuit is often incomplete and time consuming explaining, at least in part, the modest long-term results of this technique. Mapping and ablation of these arrhythmias using a three-dimensional nonfluoroscopic mapping system that allows electroanatomic reconstruction of the reentrant circuit could help in identifying the ablation targets and improve long-term outcome. The study included 20 patients (12 men, mean age 45+/-18 years) with corrected congenital heart disease (4 patients), coronary artery bypass surgery (7 patients), mitral or aortic valve replacement or reconstruction (6 patients), valve replacement and coronary revascularization (2 patients), and mitral valve replacement with maze procedure for atrial fibrillation (1 patient). Endocardial mapping with this novel system was complemented by standard electrophysiological techniques used to identify a critical isthmus of conduction. Two or more nonconductive areas of atrial tissue or surgical prosthetic material delimiting a critical isthmus of conduction were identified in every patient. Radiofrequency linear applications spanning two to more boundaries successfully eliminated the tachycardia in every patient. At a follow-up of 11.5+/-5.1 months (range 17-5 months), two (10%) patients developed a new clinical arrhythmia. The remaining 18 had no recurrences off medical therapy. Mean fluoroscopy time was 45.7+/-15.2 minutes for patients with a single scar and 89+/-41.2 minutes in patients with two or more scars. In conclusions, this new nonfluoroscopic mapping system offers the opportunity to achieve a high rate of cure of complex macroreentrant atrial tachycardias by facilitating reconstruction of the macroreentrant circuit and its boundaries.     

Concordance between an electroanatomic mapping system and cardiac MRI in arrhythmogenic right ventricular cardiomyopathy

A 29-year-old man presenting with syncopal ventricular tachycardia was diagnosed with arrhythmogenic right ventricular (RV) cardiomyopathy. Cardiac magnetic resonance imaging (MRI) revealed an unequivocal dyskinetic segment at the basal portion of the RV lateral free wall. Three-dimensional electroanatomic voltage mapping using the EnSite NavX system recorded a low voltage area corresponding to the diseased portion of the right ventricle identified by MRI. This report describes concordance between cardiac MRI and this novel mapping system in arrhythmogenic RV cardiomyopathy.     

Ablation of noninducible idiopathic left ventricular tachycardia using a noncontact map acquired from a premature complex with tachycardia morphology

We describe use of a novel noncontact system to permit mapping in a noninducible patient from a single premature ventricular complex with tachycardia morphology, thus guiding successful ablation after two previously failed conventional efforts. The instantaneous global electroanatomic map demonstrated fascicular macroreentry. Subsequent to ablation at an inferolateral site, there has been no clinical recurrence despite difficult arrhythmia control preprocedure. This case demonstrated that noncontact mapping can be used to create a potential map to guide successful ablation from a single premature ventricular complex in a patient with idiopathic left ventricular tachycardia that became noninducible at electrophysiological study.     

Noninvasive diagnosis of a wide QRS complex tachycardia mechanism by programmed atrial and ventricular stimulation using a dual chamber defibrillator

Stored atrial and ventricular electrograms retrieved from dual chamber implantable defibrillators facilitate the diagnosis of arrhythmias. This case also illustrates the usefulness of programmed atrial and ventricular stimulation for noninvasive rhythm diagnosis in patients with a wide QRS tachycardia and an implantable defibrillator.