Maximizing the Effectiveness of Ablation for Arrhythmias in the Congenital Heart Patients.

Arrhythmias are common in adults with congenital heart disease and account for a large proportion of hospitalizations. The complex anatomical heterogeneity, often in the presence of a delicate hemodynamic system, presents a significant electrophysiological challenge. This review outlines current clinical practice and advances in maximizing the effectiveness of ablation for arrhythmias in congenital heart patients.

A randomized prospective mechanistic cardiac magnetic resonance study correlating catheter stability, late gadolinium enhancement and 3 year clinical outcomes in robotically assisted vs. standard catheter ablation.

AIMS: To prospectively compare cardiac magnetic resonance late gadolinium enhancement (LGE) findings created by standard vs. robotically assisted catheter ablation lesions and correlate these with clinical outcomes. METHODS AND RESULTS: Forty paroxysmal atrial fibrillation patients (mean age 54 ± 13.8 years) undergoing first left atrial ablation were randomized to either robotic-assisted navigation (Hansen Sensei(®) X) or standard navigation. Pre-procedural, acute (24 h post-procedure) and late (beyond 3 months) scans were performed with LGE and T2W imaging sequences and percentage circumferential enhancement around the pulmonary vein (PV) antra were quantified. Baseline pre-procedural enhancements were similar in both groups. On acute imaging, mean % encirclements by LGE and T2W signal were 72% and 80% in the robotic group vs. 60% (P = 0.002) and 76%(P = 0.45) for standard ablation. On late imaging, the T2W signal resolved to baseline in both groups. Late gadolinium enhancement remained the predominant signal with 56% encirclement in the robotic group vs. 45% in the standard group (P = 0.04). At 6 months follow-up, arrhythmia-free patients had an almost similar mean LGE encirclement (robotic 64%, standard 60%, P = 0.45) but in recurrences, LGE was higher in the robotic group (43% vs. 30%, P = 0.001). At mean 3 years follow-up, 1.3 procedures were performed in the robotic group compared with 1.9 (P < 0.001) in the standard to achieve a success rate of 80% vs. 75%. CONCLUSION: Robotically assisted ablation results in greater LGE around the PV antrum. Effective lesions created through improved catheter stability and contact force during initial treatment may have a role in reducing subsequent re-do procedures.

Quantitative magnetic resonance imaging analysis of the relationship between contact force and left atrial scar formation after catheter ablation of atrial fibrillation.

BACKGROUND: Catheter contact force (CF) is an important determinant of radiofrequency (RF) lesion quality during pulmonary vein isolation (PVI). Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) allows good visualization of ablation lesions. OBJECTIVE: This study describes a new technique to examine the relationship between CF during RF delivery and LGE signal intensity (SI) following PVI. METHODS: Six patients underwent PVI for paroxysmal AF using a CF-sensing catheter and following preprocedural MRI. During ablation, CF-time integral (FTI) and position was documented for each RF application. All patients underwent repeat LGE MRI 3 months later. The LGE SIs were projected onto a MRI-derived 3-dimensional left atrial (LA) shell and a CF map was generated on the same shell. The entire LA surface was divided into 5 mm(2) segments. Force and LGE maps were fused and compared for each 5 mm(2) zone. An effective lesion was defined when MRI-defined scar occupied >90% of a 5 mm(2) analysis zone. RESULTS: Acute PVI was achieved in 100%. Two hundred sixty-eight RF lesions were tagged on the LA shells and given a lesion-specific FTI. Increasing FTI correlated with increased LGE SI, which was greater when the FTI was > 1,200 gs. Below an FTI of 1,200 gs, an increment in the FTI resulted in only a small increment in scar, whereas above 1,200 gs an increment in the FTI resulted in a large change of scar. CONCLUSION: There is a correlation between FTI and LGE SI in MRI following AF ablation. Real-time FTI maps are feasible and may prevent inadequate lesion formation.

An anthropomorphic phantom for atrial transseptal puncture simulation training.

BACKGROUND: Transseptal puncture (TSP) is a critical prerequisite for left-sided cardiac interventions, such as atrial fibrillation (AF) ablation and left atrial appendage closure. Despite its routine nature, TSP can be technically demanding and carries a risk of complications. This study presents a novel, patient-specific, anthropomorphic phantom for TSP simulation training that can be used with X-ray fluoroscopy and ultrasound imaging. METHODS: The TSP phantom was developed using additive manufacturing techniques and features a replaceable fossa ovalis (FO) component to allow for multiple punctures without replacing the entire model. Four cardiologists and one cardiology trainee performed TSP on the simulator, and their performance was assessed using four metrics: global isotropy index, distance from the centroid, time taken to perform TSP, and a set of 5-point Likert scale questions to evaluate the clinicians' perception of the phantom's realism and utility. RESULTS: The results demonstrate the simulator's potential as a training tool for interventional cardiology, providing a realistic and controllable environment for clinicians to refine their TSP skills. Experienced cardiologists tended to cluster their puncture points closer to regions of the FO associated with higher global isotropy index scores, indicating a relationship between experience and optimal puncture localization. The questionnaire analysis revealed that participants generally agreed on the phantom's realistic anatomical representation and ability to accurately visualize the TSP site under fluoroscopic guidance. CONCLUSIONS: The TSP simulator can be incorporated into training programs, offering trainees the opportunity to improve tool handling, spatial coordination, and manual dexterity prior to performing the procedure on patients. Further studies with larger sample sizes and longitudinal assessments are needed to establish the simulator's impact on TSP performance and patient outcomes.

The current practice and perception of cardiac implantable electronic device transvenous lead extraction in the UK.

AIMS: The number of patients requiring an extraction of cardiac implantable electronic devices (CIEDs) is rising. Lead extraction of chronically implanted leads is a highly specialized procedure and the Heart Rhythm Society published a consensus document outlining best practice. We sought to ascertain the current practice and perception of lead extraction in the UK. METHODS AND RESULTS: A prospective e-mail survey consisting of 21 questions was sent to members of Heart Rhythm UK. Key areas for exploration included case volume, settings for extraction procedures, levels of surgical support, preferred techniques, and the perceptions of difficulty, risk, morbidity, and mortality associated with lead extraction. Thirty responses were received giving a response rate of 9.3%. Eighty-three per cent of responders performed extractions regularly and of these 92% were electrophysiologists. Median number of cases performed per year was 13 (interquartile range 6-26). Fifty-six per cent performed <20 procedures per year. Eighty per cent of procedures were performed in the electrophysiology (EP) laboratory and of these 50% had no identifiable surgeon or operating theatre on standby. Mechanical dissection sheaths were the most widely used method of extraction after failure of manual traction (63%). The risk of minor complications was perceived to be 4% or less by the majority of respondents across the device range. The same measure for major complications and death was 2 and 1%, respectively. CONCLUSION: Increased operator caseload and closer links between EP extractors and surgeons should be seen as achievable goals.

Cardiac implantable electronic device-related endocarditis: a 12-year single-centre experience.

BACKGROUND: The incidence of cardiac implantable electrical device endocarditis (CIEDE) is increasing, but CIEDE remains a relatively poorly described infection. This case series describes our experience of the condition at a tertiary referral centre in London over a 12-y period. METHODS: We identified cases using an endocarditis database containing prospectively collected clinical and microbiological information. We also used data recorded in an electronic database of all cardiac implantable electrical device-related procedures. RESULTS: Thirty cases of CIEDE were treated at our institution during the study period. Presentation was most commonly with fever, and 93% of our patients had positive blood cultures. Vegetations were identified on echocardiography in only 70% of patients, although a transoesophageal echocardiogram (TOE) was performed in only half of the cases. Sixty-seven percent of our cases were defined as definite endocarditis according to the modified Duke criteria for infective endocarditis. Twenty-three patients underwent percutaneous explantation of their infected CIED (including 6 patients with vegetations greater than 10 mm in diameter), while 5 underwent surgical explantation. The overall in-hospital mortality was 17%. CONCLUSIONS: Our data confirm the life-threatening nature of CIEDE in a UK population. In addition, our experience suggests that percutaneous extraction of devices with large adherent vegetations may be safe, and that the selective use of TOE may not compromise outcomes. Lastly, we show that the modified Duke criteria do not perform very well with this condition, suggesting a need for specific, validated criteria for diagnosing CIEDE.

Percutaneous extraction of cardiac implantable electronic devices (CIEDs) in octogenarians.

BACKGROUND: As the population receiving cardiac device therapy ages, the number of extraction procedures performed in octogenarians is increasing. This group has more comorbidities and may be at higher risk of such procedures. OBJECTIVES: Document the safety and success of percutaneous lead extraction in octogenarians. METHODS: All extraction cases performed between January 2001 and April 2011 entered into a computer database were analyzed for patient characteristics and indications, extraction technique, procedural success, and complications. Success and complications were classified according to the Heart Rhythm Society consensus statement. Outcomes in octogenarians were compared to younger patients undergoing extraction during the same period. RESULTS: Four hundred and six cases were performed: 72 procedures in octogenarians (mean age 84, range 80-95) and 334 in younger adults (mean age 62, range 20-79). Octogenarians had a greater number of comorbidities per case. Infection was the commonest indication for extraction in both groups. One hundred forty-one leads were extracted in octogenarians and 657 in younger patients. Laser assistance was required in 51.4% of octogenarians versus 49.7% of younger patients. Procedural success was achieved in 71/72 (98.6%) octogenarians versus 329/334 (98.5%) younger patients. No procedural mortality occurred in either group. Overall, complications were more frequent in octogenarians with major and minor complications occurring in 2.8 and 8.3% of octogenarians versus 0.6 and 3.0% of younger patients (P = 0.014). CONCLUSIONS: Procedural success was equally high in octogenarians and younger patients. Percutaneous lead extraction can be performed effectively and safely in octogenarians and is associated with a higher complication rate but no increased mortality.

A linear ablating system in the left and right atrium: feasibility, catheter performance and clinical results.

INTRODUCTION: We describe the use of a ablating system to compartmentalise and regionally isolate the atria in paroxysmal and persistent atrial fibrillation (AF). METHODS: 40 patients were studied, 25 paroxysmal AF and 14 persistent AF. One patient enrolled was later found to be in left atrial flutter and was excluded. The Cardima Revelation® TX catheter system with Intellitemp® Radiofrequency (RF) energy control device and a Medtronic Atakar® RF generator were used to place wide area circumferential ablations to achieve conduction block into the left and right sided pulmonary veins. Roof lines and mitral isthmus lines were also performed. In patients with persistent AF and in repeat procedures, right atrial compartmentalisation was performed with an anterior superior vena cava (SVC) to inferior vena cava (IVC) line and a septal SVC to IVC line. RESULTS: At 6 months, 18 of the 39 patients were asymptomatic, 10 had improved symptoms and 22 were in sinus rhythm. In the paroxysmal group, 11 were asymptomatic, 7 had improved symptoms and 16 (64%) were in sinus rhythm. In the persistent group, 7 were asymptomatic, 3 had improved symptoms and 6 (43%) were in sinus rhythm. The total group AF burden was 37.8 ± 5.4 hrs pre-procedure and 23.1 ± 5.1 hrs at 6 months post procedure. Mean temperature, impedance and power recorded at each pole demonstrated effective power delivery at all poles. No catheter charring was observed, complication rates were comparable to standard AF ablation technique. CONCLUSION: Linear ablation in the left and right atria to mimic Cox's Maze is feasible and safe using this ablating system.

Percutaneous lead and system extraction in patients with cardiac resynchronization therapy (CRT) devices and coronary sinus leads.

BACKGROUND: Cardiac resynchronization therapy (CRT) device and coronary sinus (CS) lead extraction is required due to the occurrence of system infection, malfunction, or upgrade. Published series of CS lead extraction are limited by small sample sizes. We present a 10-year experience of CRT device and CS lead extraction. METHODS: All lead extractions between 2000 and 2010 were entered into a computer database. From these, a cohort of 71 cases involving a CRT device or CS lead was analyzed for procedural method, success, and complications. RESULTS: Sixty coronary sinus leads were extracted in 71 cases (median age 71 years; 90% male) by manual traction/locking stylets (n = 54) or using a laser sheath (n = 6). Procedural success was achieved in 98% of CS leads. A total of 143 non-CS leads were extracted, with laser required in 46% of cases. The mean duration of lead implantation was 35.8 months (range 1-116 months) and 2.86 ± 1.07 leads were extracted per case. CRT extraction case load increased significantly over time. Minor complications occurred in four (5.6%) cases and major complications in one (1.4%) case. There were no intraprocedural deaths, but two deaths occurred within 30 days of extraction. CONCLUSIONS: Our 10-year experience confirms that percutaneous removal of CS leads can be achieved with high procedural success. Our recorded complication rates are no higher than those of non-CS lead extraction series, and should be taken in the context of the frail nature of CRT patients. Ongoing audit of procedure success and complications will be required to further guide best practice in CS lead extraction.

Real-time registration of 3D echo to x-ray fluoroscopy based on cascading classifiers and image registration.

Three-dimensional (3D) transesophageal echocardiography (TEE) is one of the most significant advances in cardiac imaging. Although TEE provides real-time 3D visualization of heart tissues and blood vessels and has no ionizing radiation, x-ray fluoroscopy still dominates in guidance of cardiac interventions due to TEE having a limited field of view and poor visualization of surgical instruments. Therefore, fusing 3D echo with live x-ray images can provide a better guidance solution. This paper proposes a novel framework for image fusion by detecting the pose of the TEE probe in x-ray images in real-time. The framework does not require any manual initialization. Instead it uses a cascade classifier to compute the position and in-plane rotation angle of the TEE probe. The remaining degrees of freedom are determined by fast marching against a template library. The proposed framework is validated on phantoms and patient data. The target registration error for the phantom was 2.1 mm. In addition, 10 patient datasets, seven of which were acquired from cardiac electrophysiology procedures and three from trans-catheter aortic valve implantation procedures, were used to test the clinical feasibility as well as accuracy. A mean registration error of 2.6 mm was achieved, which is well within typical clinical requirements.

Pacemaker and defibrillator lead extraction: predictors of mortality during follow-up.

BACKGROUND: Extraction of cardiac implantable electric devices is an accepted procedure when systems become infected or malfunction. However, there is an associated morbidity and mortality. We report our 5-year experience and identify predictors of mortality, and long-term follow-up. METHODS: We analyzed extraction data from January 2003 to November 2007. Extraction methods used were: locking stylets, telescoping sheaths +/- laser, and femoral work stations. RESULTS: One hundred and eighty-three cases were referred, aged 65 +/- 16 years (range 28-83); 76% were males. Mean implant time was 75 months (range 4-312 months) and indications were: pocket infection (48%), nonfunctioning lead (22%), erosion through skin (18%), endocarditis/septicemia (11%), bilateral superior vena cava thrombosis (0.5%), and painful lead (0.5%). The number of leads extracted were 369, with complete removal in 90.7% and partial in 7.6%. There were no intraoperative deaths but five (2.7%) died within the same admission as their extraction from overwhelming sepsis. Twelve deaths (6.6%) occurred during an average follow-up of 965 days (range 40-1670). Multivariate logistic regression demonstrated that C-reactive protein preprocedure was predictive of acute in-hospital mortality. CONCLUSIONS: Intravascular lead extraction is a safe and efficient method of removing leads. However, there is a subgroup of patients with systemic sepsis with raised inflammatory markers who are at high risk of in-hospital mortality. Long-term follow-up demonstrates mortality which is a marker of the underlying etiology for device implantation, with heart failure patients particularly at risk.

A shocking lead in the coronary sinus.

Placement of leads into the coronary sinus (CS) is now routinely used for cardiac resynchronization therapy. However, the CS can also be used for the placement of defibrillator shock leads. There is evidence demonstrating that CS leads in situ for the short and medium term can be successfully removed utilizing percutaneous methods. We report a case of CS laser lead extraction where a defibrillator lead had been in place for almost 10 years.

Extraction of chronic pacemaker and defibrillator leads from the coronary sinus: laser infrequently used but required.

AIMS: Cardiac resynchronization therapy is an accepted treatment for heart failure but it may be necessary to explant these systems along with their leads. The evidence base for coronary sinus (CS) lead extractions is limited. We aimed to evaluate the percutaneous removal of these leads and the utility of laser extraction when necessary. METHODS AND RESULTS: Of 265 patients referred for lead extraction between January 2004 and June 2008, 32 (12.1%) involved CS leads (30 males, mean age 67 years). Mean implantation time was 26.5 +/- 28.7 months (range 1-116 months). Indications for extraction were pocket infection (34.4%), lead malfunction (43.8%), skin erosion (15.6%), and endocarditis (6.2%). Twenty-eight (87.5%) CS leads were removed with manual traction, with laser utilized in four cases (12.5%). No major complications of CS laceration, pericardial effusion, emergency surgery, or death occurred. CONCLUSION: Our experience supports the percutaneous extraction of CS leads as a safe and effective procedure including the utility of laser when necessary.

Long-term follow-up of normal and structural heart ventricular tachycardia catheter ablation: real-world experience from a UK tertiary centre.

Background: Ventricular tachycardia (VT) is associated with increased morbidity and mortality. There is growing evidence for the effectiveness of catheter ablation in improving outcomes in patients with recurrent VT. Consequently the threshold for referral for VT ablation has fallen over recent years, resulting in increased number of procedures. Objective: To evaluate the effectiveness and safety of VT ablation in a real-world tertiary centre setting. Methods: This is a prospective analysis of all VT ablation cases performed at University Hospital Coventry. Follow-up data were obtained from review of electronic medical records and patient interview. The primary endpoint for normal heart VT was death, cardiovascular hospitalisation and VT recurrence, and for structural heart VT was arrhythmic death, VT storm (>3 episodes within 24 hours) or appropriate shock. Results: Forty-seven patients underwent 53 procedures from January 2012 to January 2018. The mean age ±SD was 57±15 years, 68% were male, 81% were Caucasian and 66% were elective cases. The aetiology of VT included normal heart (49%), ischaemic cardiomyopathy (ICM, 36%), dilated cardiomyopathy (9%), hypertrophic cardiomyopathy (4%) and valvular heart disease (2%). Procedural success occurred in 83%, with six major complications. After a median follow-up of 231 days (lower quartile 133, upper quartile 631), the primary outcome occurred in 28% of patients. There were two non-arrhythmic deaths (4%). At a median follow-up of 193 days (129-468), the primary outcome occurred in 19% of patients with ICM, while VT storm/appropriate shocks occurred in three patients (17%). Conclusions: Our real-world registry confirms that VT ablation is safe, and is associated with high acute procedural success and long-term outcomes comparable with randomised controlled studies.

A case of diaphragmatic pacing with cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) is now an accepted treatment for heart failure [McAlister et al. in Cardiac resynchronization therapy for patients with left ventricular systolic dysfunction: a systematic review. JAMA 2007;297:2502-14.]. In addition to the complications associated with standard pacemaker implants, CRT procedures have their own additional complications such as coronary sinus dissection, diaphragmatic stimulation, and longer implant times. We present a case of CRT implantation which illustrates these problems because of an unusual complication.

Effects of tracer arrival time on the accuracy of high-resolution (voxel-wise) myocardial perfusion maps from contrast-enhanced first-pass perfusion magnetic resonance.

First-pass perfusion cardiac magnetic resonance(CMR) allows the quantitative assessment of myocardial blood flow(MBF). However, flow estimates are sensitive to the delay between the arterial and myocardial tissue tracer arrival time (tOnset) and the accurate estimation of MBF relies on the precise identification of tOnset . The aim of this study is to assess the sensitivity of the quantification process to tOnset at voxel level. Perfusion data were obtained from series of simulated data, a hardware perfusion phantom, and patients. Fermi deconvolution has been used for analysis. A novel algorithm, based on sequential deconvolution,which minimizes the error between myocardial curves and fitted curves obtained after deconvolution, has been used to identify the optimal tOnset for each region. Voxel-wise analysis showed to be more sensitive to tOnset compared to segmental analysis. The automated detection of the tOnset allowed a net improvement of the accuracy of MBF quantification and in patients the identification of perfusion abnormalities in territories that were missed when a constant user-selected tOnset was used. Our results indicate that high-resolution MBF quantification should be performed with optimized tOnset values at voxel level.

A Method to Standardize Quantification of Left Atrial Scar From Delayed-Enhancement MR Images.

Delayed-enhancement magnetic resonance imaging (DE-MRI) is an effective technique for detecting left atrial (LA) fibrosis both pre and postradiofrequency ablation for the treatment of atrial fibrillation. Fixed thresholding models are frequently utilized clinically to segment and quantify scar in DE-MRI due to their simplicity. These methods fail to provide a standardized quantification due to interobserver variability. Quantification of scar can be used as an endpoint in clinical studies and therefore standardization is important. In this paper, we propose a segmentation algorithm for LA fibrosis quantification and investigate its performance. The algorithm was validated using numerical phantoms and 15 clinical data sets from patients undergoing LA ablation. We demonstrate that the approach produces good concordance with expert manual delineations. The method offers a standardized quantification technique for evaluation and interpretation of DE-MRI scans.

Novel System for Real-Time Integration of 3-D Echocardiography and Fluoroscopy for Image-Guided Cardiac Interventions: Preclinical Validation and Clinical Feasibility Evaluation.

Real-time imaging is required to guide minimally invasive catheter-based cardiac interventions. While transesophageal echocardiography allows for high-quality visualization of cardiac anatomy, X-ray fluoroscopy provides excellent visualization of devices. We have developed a novel image fusion system that allows real-time integration of 3-D echocardiography and the X-ray fluoroscopy. The system was validated in the following two stages: 1) preclinical to determine function and validate accuracy; and 2) in the clinical setting to assess clinical workflow feasibility and determine overall system accuracy. In the preclinical phase, the system was assessed using both phantom and porcine experimental studies. Median 2-D projection errors of 4.5 and 3.3 mm were found for the phantom and porcine studies, respectively. The clinical phase focused on extending the use of the system to interventions in patients undergoing either atrial fibrillation catheter ablation (CA) or transcatheter aortic valve implantation (TAVI). Eleven patients were studied with nine in the CA group and two in the TAVI group. Successful real-time view synchronization was achieved in all cases with a calculated median distance error of 2.2 mm in the CA group and 3.4 mm in the TAVI group. A standard clinical workflow was established using the image fusion system. These pilot data confirm the technical feasibility of accurate real-time echo-fluoroscopic image overlay in clinical practice, which may be a useful adjunct for real-time guidance during interventional cardiac procedures.