Computer Simulation of Catheter Cryoablation for Pulmonary Vein Isolation (original) (raw)
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Biomedical Engineering, 2011
Cryoablation for curing cardiac arrhythmias is a promising approach in clinical cardiology. It appears to have major advantages compared to ablation by radiofrequency. The aim of cryoablation is to electrically inactivate cardiac tissue and thus finish arrhythmia by means of cooling the related tissue. Modeling and simulation of the spatiotemporal distribution of the related non-stationary temperature field in myocardial tissue may help to optimize and thus improve the cryoablation procedure. In this work a representative geometry comprised of the cryoablation catheter and myocardial tissue was constructed and the spatio-temporal distribution of the temperature fields in time was simulated by cryoablation. The related physical model for simulation was based on the Bioheat Equation, which considers the specific parameters of organic tissue (i.e., apart from heat capacity and conductivity the production of heat due to metabolic processes and the heat transfer due to arterial blood flow in veins and arteries). The Finite-Element-Method and explicit Eulerscheme was employed for solving the non-stationary problem. The results of two different simulation scenarios showed that simulating the spatio-temporal temperature fields through the cooling process of cryoablation is feasible and should help to, broaden understanding of, and optimize this process in the future.
Cryoablation of the pulmonary veins using a novel balloon catheter
Journal of Interventional Cardiac Electrophysiology, 2006
Introduction. Pulmonary vein (PV) isolation has emerged as a promising technique for the treatment of patients with drug-refractory atrial fibrillation, however, the achievement of transmural lesions has remained a challenge. We evaluated the ability of a novel balloon-based cryogenic catheter system in achieving transmural lesions for PV isolation.
Cryoballoon temperature predicts acute pulmonary vein isolation
Heart Rhythm, 2011
BACKGROUND Cryoballoon pulmonary vein isolation (PVI) currently requires a long cryoballoon application (CBA) time of 240 to 300 seconds, thus repeated ineffective CBA prolongs procedure duration. We hypothesized that cryoballoon temperature (CBT) may be used to discriminate between effective and ineffective CBA during freezing.
Planning and Simulation of Percutaneous Cryoablation
AASRI Procedia, 2014
New technological methods to assist percutaneous cryoablation procedures are here presented, namely a planning software and a simulation algorithm. The first has the role to calculate a feasible displacement of the tools to ensure an effective ablation of the lesion, satisfying well-specified procedural constraints. Starting from intra-operative CT scans of the patient, a virtual model of the anatomical site is obtained and uploaded. The displacement of the cryoprobes is computed in order to cover the whole volume of the tumour with the developed iceball, but minimizing the damage to surrounding healthy renal tissue. On the other hand, the simulation algorithm is a graphical tool useful to assess the temperature distribution throughout the evolution of the procedure. A discrete iterative function calculates the heat transfer from the probes to the surrounding tissue within a specified three-dimensional grid: the isolation of significant isotherms can help to assess whether the whole tumour will be frozen or not. By using a real intra-operative dataset of a successful percutaneous cryoablation, the volume of the real iceball has been matched with that generated from the simulator, showing a good accuracy in terms of dimension and shape. Even though been designed to be integrated within a robotic system, this method is usable and extensible for different purposes and adapted to simulate other scenarios or procedures.
Cardiology Journal
Background: Freezing rate of second-generation cryoballoon (CB) is a biophysical parameter that could assist pulmonary vein isolation. The aim of this study is to assess freezing rate (time to reach-30°C ([TT-30C]) as an early predictor of acute pulmonary vein isolation using the CB. Methods: Biophysical data from CB freeze applications within a multicenter, nationwide CB ablation registry were gathered. Successful application (SA), was defined as achieving durable intraprocedural vein isolation with time to isolation in under 60 s (SA-TTI<60) as achieving durable vein isolation in under 60 s. Logistic regressions were performed and predictive models were built for the data set. Results: 12,488 CB applications from 1,733 atrial fibrillation (AF) ablation procedures were included within 27 centers from a Spanish CB AF ablation registry. SA was achieved in 6,349 of 9,178 (69.2%) total freeze applications, and SA-TTI<60 was obtained in 2,673 of 4,784 (55.9%) freezes and electrogram monitoring was present. TT-30C was shorter in the SA group (33.4 9.2 vs 39.3 12.1 s; p < 0.001) and SA-TTI<60 group (31.8 7.6 vs. 38.5 11.5 s; p < 0.001). Also, a 10 s increase in TT-30C was associated with a 41% reduction in the odds for an SA (odds ratio [OR] 0.59; 95% confidence interval [CI] 0.56-0.63) and a 57% reduction in the odds for achieving SA-TTI<60 (OR 0.43; 95% CI 0.39-0.49), when corrected for electrogram visualization, vein position, and application order. Conclusions: Time to reach-30°C is an early predictor of the quality of a CB application and can be used to guide the ablation procedure even in the absence of electrogram monitoring.
BioMedical Engineering OnLine, 2015
Background: Cardiac cryoablation is a minimally invasive procedure to treat cardiac arrhythmias by cooling cardiac tissues responsible for the cardiac arrhythmia to freezing temperatures. Although cardiac cryoablation offers a gentler treatment than radiofrequency ablation, longer interventions and higher recurrence rates reduce the clinical acceptance of this technique. Computer models of ablation scenarios allow for a closer examination of temperature distributions in the myocardium and evaluation of specific effects of applied freeze-thaw protocols in a controlled environment. Methods: In this work multiple intervention scenarios with two freeze-thaw cycles were simulated with varying durations and starting times of the interim thawing phase using a finite element model verified by in-vivo measurements and data from literature. To evaluate the effects of different protocols, transmural temperature distributions and iceball dimensions were compared over time. Cryoadhesion durations of the applicator were estimated in the interim thawing phase with varying thawing phase starting times. In addition, the increase of cooling rates was compared between the freezing phases, and the thawing rates of interim thawing phases were analyzed over transmural depth. Results: It could be shown that the increase of cooling rate, the regions undergoing additional phase changes and depths of selected temperatures depend on the chosen ablation protocol. Only small differences of the estimated cryoadhesion duration were found for ablation scenarios with interim thawing phase start after 90 s freezing. Conclusions: By the presented model a quantification of effects responsible for cell death is possible, allowing for the analysis and optimization of cryoablation scenarios which contribute to a higher clinical acceptance of cardiac cryoablation.
Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology, 2016
There is no objective, early indicator of occlusion quality, and efficacy of cryoballoon pulmonary vein isolation. As previous experience suggests that the initial cooling rate correlates with these parameters, we investigated the slope of the initial temperature drop as an objective measure. A systematic evaluation of 523 cryoapplications in 105 patients using a serial ROC-AUC analysis was performed. We found the slope of a linear regression of the temperature-time function to be a good predictor (PPV 0.9, specificity 0.72, sensitivity 0.71, and ROC-AUC 0.75) of acute isolation. It also correlated with nadir temperatures (P< 0.001, adjusted R(2)= 0.43), predicted very low nadir temperatures, and varied according to visual occlusion grades (ANOVA P< 0.001). About 25 s after freeze initiation, the temperature-time slope predicts important key characteristics of a cryoablation, such as nadir temperature. The slope is the only reported predictor to actually precede acute isolatio...
Heart rhythm : the official journal of the Heart Rhythm Society, 2016
Limited data exists on cryoablation of atrial fibrillation (Cryo-AF) using the newly-available third-generation (AFA-ST) cryoballoon. In this multicenter study, we evaluated the safety and efficacy of Cryo-AF using the AFA-ST versus the second-generation (AFA) cryoballoon. We examined the procedural safety and efficacy and acute and mid-term results from 355 consecutive patients (72% with paroxysmal AF) who underwent a first-time Cryo-AF using AFA-ST (n=102) or AFA (n=253). Acute isolation was achieved in 99.6% of all PVs (AFA-ST=100% vs. AFA=99.4%; p=0.920). Time-to-pulmonary vein (PV) isolation (TT-PVI) was recorded in 89.2% of PVs using AFA-ST versus 60.2% with AFA; p<0.001. PVs targeted with AFA-ST required fewer applications (1.6±0.8 vs. 1.7±0.8; p=0.023), whereas there were no differences in balloon nadir temperature (AFA-ST=-47.0±7.3⁰C vs. AFA=-47.5±7.8⁰C; p=0.120) or thaw time (AFA-ST=41±24 sec vs. AFA=44±28 sec; p=0.056). However, AFA-ST was associated with shorter left ...
Clinical Research in Cardiology, 2009
Background Cryoballoon ablation (Arctic Front, Cryocath TM ) represents a novel technology for pulmonary vein isolation (PVI). The initial phase of a freeze is crucial for cryolesion formation which is determined by local temperature depending on blood flow. We investigated the impact of right ventricular rapid pacing (RVRP) on temperature kinetics in patients (pts) with paroxysmal atrial fibrillation (PAF). Methods and results Right ventricular rapid pacing was performed from the RV apex. Absolute minimal temperature (MT,°C), temperature slopes [time (s) to 80% MT; dT/dt), area under the curve (AUC) and arterial blood pressure (ABP, mmHg) were compared (group I: with RVRP vs. group II: without RVRP). RVRP (mean duration 55 ± 7 s) was performed in 11 consecutive PAF pts (41 PVs, age 58 ± 9 years, LA size 44 ± 6 mm, normal ejection fraction). Only freezes with identical balloon positions were analyzed (11/41 PVs). RVRP (cycle length 333 ± 3 ms) induced a significant drop in ABP (group I: 45 ± 3 mmHg vs. group II: 100 ± 18 mmHg, p \ 0.001). MT was not different between group I and group II (-45.0 ± 4.4 vs. -44.3 ± 3.4°C, p = 0.46), whereas slope (38.0 ± 4.6 s vs. 51.6 ± 14.4 s, p = 0.0034) and AUC (1090 ± 4.6 vs. 1181 ± 111.2, p = 0.02) was significantly changed. In one pt, a ventricular tachycardia was induced. PVI was achieved in 41/41 PVs. Conclusion Right ventricular rapid pacing significantly accelerates cryoballoon cooling during the initial phase of a freeze possibly suggesting improved cryolesions.