Automatic 3D Surface Reconstruction of the Left Atrium From Clinically Mapped Point Clouds Using Convolutional Neural Networks.

Point clouds are a widely used format for storing information in a memory-efficient and easily manipulatable representation. However, research in the application of point cloud mapping and subsequent organ reconstruction with deep learning, is limited. In particular, current methods for left atrium (LA) visualization using point clouds recorded from clinical mapping during cardiac ablation are proprietary and remain difficult to validate. Many clinics rely on additional imaging such as MRIs/CTs to improve the accuracy of LA mapping. In this study, for the first time, we proposed a novel deep learning framework for the automatic 3D surface reconstruction of the LA directly from point clouds acquired via widely used clinical mapping systems. The backbone of our framework consists of a 30-layer 3D fully convolutional neural network (CNN). The architecture contains skip connections that perform multi-resolution processing to maximize information extraction from the point clouds and ensure a high-resolution prediction by combining features at different receptive levels. We used large kernels with increased receptive fields to address the sparsity of the point clouds. Residual blocks and activation normalization were further implemented to improve the feature learning on sparse inputs. By utilizing a light-weight design with low-depth layers, our CNN took approximately 10 s per patient. Independent testing on two cross-modality clinical datasets showed excellent dice scores of 93% and surface-to-surface distances below 1 pixel. Overall, our study may provide a more efficient, cost-effective 3D LA reconstruction approach during ablation procedures, and potentially lead to improved treatment of cardiac diseases.

Progressive modification of rotors in persistent atrial fibrillation by stepwise linear ablation.

Impact of body mass index on plasma N-terminal ProB-type natriuretic peptides in Chinese atrial fibrillation patients without heart failure.

BACKGROUND:An inverse relationship between body mass index (BMI) and circulating levels of N-terminal proB-type natriuretic peptide (NT-proBNP) has been demonstrated in subjects with and without heart failure. Obesity also has been linked with increased incidence of atrial fibrillation (AF), but its influence on NT-proBNP concentrations in AF patients remains unclear. This study aimed to investigate the effect of BMI on NT-proBNP levels in AF patients without heart failure.METHODS:A total of 239 consecutive patients with AF undergoing catheter ablation were evaluated. Levels of NT-proBNP and clinical characteristics were compared in overweight or obese (BMI≥25 kg/m2) and normal weight (BMI<25 kg/m2) patients.RESULTS:Of 239 patients, 129 (54%) were overweight or obese. Overweight or obese patients were younger, more likely to have a history of nonparoxysmal AF, hypertension, and diabetes mellitus. Levels of NT-proBNP were significantly lower in overweight or obese than in normal weight subjects (P<0.05). The relationship of obesity and decreased NT-proBNP levels persisted in subgroup of hypertension, both gender and both age levels (≥65 yrs and <65 yrs).Multivariate linear regression identified BMI as an independent negative correlate of LogNT-proBNP level.CONCLUSIONS:An inverse relationship between BMI and plasma NT-proBNP concentrations have been demonstrated in AF patients without heart failure. Overweight or obese patients with AF appear to have lower NT-proBNP levels than normal weight patients.

The training and learning process of transseptal puncture using a modified technique.

AIMS:As the transseptal (TS) puncture has become an integral part of many types of cardiac interventional procedures, its technique that was initial reported for measurement of left atrial pressure in 1950s, continue to evolve. Our laboratory adopted a modified technique which uses only coronary sinus catheter as the landmark to accomplishing TS punctures under fluoroscopy. The aim of this study is prospectively to evaluate the training and learning process for TS puncture guided by this modified technique.METHODS AND RESULTS:Guided by the training protocol, TS puncture was performed in 120 consecutive patients by three trainees without previous personal experience in TS catheterization and one experienced trainer as a controller. We analysed the following parameters: one puncture success rate, total procedure time, fluoroscopic time, and radiation dose. The learning curve was analysed using curve-fitting methodology. The first attempt at TS crossing was successful in 74 (82%), a second attempt was successful in 11 (12%), and 5 patients failed to puncture the interatrial septal finally. The average starting process time was 4.1 ± 0.8 min, and the estimated mean learning plateau was 1.2 ± 0.2 min. The estimated mean learning rate for process time was 25 ± 3 cases. Important aspects of learning curve can be estimated by fitting inverse curves for TS puncture.CONCLUSIONS:The study demonstrated that this technique was a simple, safe, economic, and effective approach for learning of TS puncture. Base on the statistical analysis, approximately 29 TS punctures will be needed for trainee to pass the steepest area of learning curve.

Improved approach to atrial septum puncture: experience in 539 cases.

BACKGROUND:The transseptal puncture technique has been widely used in therapeutic left atrium catheterization. But this technique may lead to some life-threatening complications. It can not be used widely because it is restricted by economy and deferring the transseptal puncture procedure. The aim of this study was to introduce a simple and safe transseptal puncture procedure.METHODS:The distal of coronary sinus (CS) electrode was positioned close to the lateral margin of heart, which was about at 3 o'clock at left anterior oblique (LAO) 30° referred to whole cardiac profile. It was then used as the marker for the level of fossa ovalis at posterior-anterior projection to guide the pull of transseptal needle. The midpoint between the distal CS and the posterior margin of heart at right anterior oblique (RAO) 45° view was considered as the location of fossa ovalis. Once the puncture was succeeded, the guidewire was introduced to the left superior pulmonary vein via puncture sheath after the needle was retrieved. The end of outer sheath was introduced into left atrium with the protection of guidewire. It was applied in 539 patients (316 male, 223 female; (53 ± 16) years old) who underwent catheter ablation of atrial fibrillation or left-sided atrioventricular accessory pathway.RESULTS:This transseptal approach reached 100.0% success and was succeeded in 98.9% with the first attempt. The first attempt puncture was aborted due to greater resistance to needle advancement or smaller needle curve in six patients. However, the second attempts were all succeeded after the needle curve was reshaped. There was no tamponade and embolism occurred.CONCLUSION:The atrial septum puncture approach using the location of distal CS electrode as important marker and the guidewire for protection when sending outer sheath into left atrium is reliable and safe.

Endocardial autonomic denervation of the left atrium to treat vasovagal syncope: an early experience in humans.

BACKGROUND:Vasovagal syncope (VVS) is the most common cause of recurrent syncope that can be debilitating despite optimal conventional therapy. The aim of this study was to evaluate the feasibility and efficacy of selective endocardial autonomic denervation in left atrium (LA) as an alternative treatment strategy in patients with highly symptomatic VVS.METHODS AND RESULTS:Ten consecutive patients (mean age, 50.4±6.4 years; 7 women) with a medium of 3.5 (range, 2-20) recurrent episodes of VVS during the preceding year and positive head-up tilt testing in whom standard therapies were ineffective or poorly tolerated were enrolled. Ganglionated plexi (GP) in the LA, identified by high-frequency stimulation, was targeted by radiofrequency catheter ablation. The patients were then followed up at 3, 6, 12, 24, and 36 months, including repeated head-up tilt testing and Holter at 3 and 12 months. Radiofrequency energy was applied at the left superior GP in 10 patients, right anterior GP in 5, and left inferior GP in 3, using an 8-mm ablation catheter. Vagal response, defined as transient ventricular asystole, atrioventricular block, or an increase in R-R interval by 50%, was observed during ablation in all GP sites. The end point of procedure was the inhibition of the vagal response at target sites. At 30±16 (range, 13-55) months of follow-up, no patient had any recurrence of syncope and all patients had significant improvement in symptoms, but 5 of 10 patients reported transient prodromes. No complications occurred.CONCLUSIONS:Comprehensive endocardial autonomic denervation of the LA demonstrates the feasibility of treating VVS in medium-term follow-up.

Automatic 3D Surface Reconstruction of the Left Atrium From Clinically Mapped Point Clouds Using Convolutional Neural Networks.

Point clouds are a widely used format for storing information in a memory-efficient and easily manipulatable representation. However, research in the application of point cloud mapping and subsequent organ reconstruction with deep learning, is limited. In particular, current methods for left atrium (LA) visualization using point clouds recorded from clinical mapping during cardiac ablation are proprietary and remain difficult to validate. Many clinics rely on additional imaging such as MRIs/CTs to improve the accuracy of LA mapping. In this study, for the first time, we proposed a novel deep learning framework for the automatic 3D surface reconstruction of the LA directly from point clouds acquired via widely used clinical mapping systems. The backbone of our framework consists of a 30-layer 3D fully convolutional neural network (CNN). The architecture contains skip connections that perform multi-resolution processing to maximize information extraction from the point clouds and ensure a high-resolution prediction by combining features at different receptive levels. We used large kernels with increased receptive fields to address the sparsity of the point clouds. Residual blocks and activation normalization were further implemented to improve the feature learning on sparse inputs. By utilizing a light-weight design with low-depth layers, our CNN took approximately 10 s per patient. Independent testing on two cross-modality clinical datasets showed excellent dice scores of 93% and surface-to-surface distances below 1 pixel. Overall, our study may provide a more efficient, cost-effective 3D LA reconstruction approach during ablation procedures, and potentially lead to improved treatment of cardiac diseases.

Progressive modification of rotors in persistent atrial fibrillation by stepwise linear ablation.

Impact of body mass index on plasma N-terminal ProB-type natriuretic peptides in Chinese atrial fibrillation patients without heart failure.

BACKGROUND:An inverse relationship between body mass index (BMI) and circulating levels of N-terminal proB-type natriuretic peptide (NT-proBNP) has been demonstrated in subjects with and without heart failure. Obesity also has been linked with increased incidence of atrial fibrillation (AF), but its influence on NT-proBNP concentrations in AF patients remains unclear. This study aimed to investigate the effect of BMI on NT-proBNP levels in AF patients without heart failure.METHODS:A total of 239 consecutive patients with AF undergoing catheter ablation were evaluated. Levels of NT-proBNP and clinical characteristics were compared in overweight or obese (BMI≥25 kg/m2) and normal weight (BMI<25 kg/m2) patients.RESULTS:Of 239 patients, 129 (54%) were overweight or obese. Overweight or obese patients were younger, more likely to have a history of nonparoxysmal AF, hypertension, and diabetes mellitus. Levels of NT-proBNP were significantly lower in overweight or obese than in normal weight subjects (P<0.05). The relationship of obesity and decreased NT-proBNP levels persisted in subgroup of hypertension, both gender and both age levels (≥65 yrs and <65 yrs).Multivariate linear regression identified BMI as an independent negative correlate of LogNT-proBNP level.CONCLUSIONS:An inverse relationship between BMI and plasma NT-proBNP concentrations have been demonstrated in AF patients without heart failure. Overweight or obese patients with AF appear to have lower NT-proBNP levels than normal weight patients.

The training and learning process of transseptal puncture using a modified technique.

AIMS:As the transseptal (TS) puncture has become an integral part of many types of cardiac interventional procedures, its technique that was initial reported for measurement of left atrial pressure in 1950s, continue to evolve. Our laboratory adopted a modified technique which uses only coronary sinus catheter as the landmark to accomplishing TS punctures under fluoroscopy. The aim of this study is prospectively to evaluate the training and learning process for TS puncture guided by this modified technique.METHODS AND RESULTS:Guided by the training protocol, TS puncture was performed in 120 consecutive patients by three trainees without previous personal experience in TS catheterization and one experienced trainer as a controller. We analysed the following parameters: one puncture success rate, total procedure time, fluoroscopic time, and radiation dose. The learning curve was analysed using curve-fitting methodology. The first attempt at TS crossing was successful in 74 (82%), a second attempt was successful in 11 (12%), and 5 patients failed to puncture the interatrial septal finally. The average starting process time was 4.1 ± 0.8 min, and the estimated mean learning plateau was 1.2 ± 0.2 min. The estimated mean learning rate for process time was 25 ± 3 cases. Important aspects of learning curve can be estimated by fitting inverse curves for TS puncture.CONCLUSIONS:The study demonstrated that this technique was a simple, safe, economic, and effective approach for learning of TS puncture. Base on the statistical analysis, approximately 29 TS punctures will be needed for trainee to pass the steepest area of learning curve.

Improved approach to atrial septum puncture: experience in 539 cases.

BACKGROUND:The transseptal puncture technique has been widely used in therapeutic left atrium catheterization. But this technique may lead to some life-threatening complications. It can not be used widely because it is restricted by economy and deferring the transseptal puncture procedure. The aim of this study was to introduce a simple and safe transseptal puncture procedure.METHODS:The distal of coronary sinus (CS) electrode was positioned close to the lateral margin of heart, which was about at 3 o'clock at left anterior oblique (LAO) 30° referred to whole cardiac profile. It was then used as the marker for the level of fossa ovalis at posterior-anterior projection to guide the pull of transseptal needle. The midpoint between the distal CS and the posterior margin of heart at right anterior oblique (RAO) 45° view was considered as the location of fossa ovalis. Once the puncture was succeeded, the guidewire was introduced to the left superior pulmonary vein via puncture sheath after the needle was retrieved. The end of outer sheath was introduced into left atrium with the protection of guidewire. It was applied in 539 patients (316 male, 223 female; (53 ± 16) years old) who underwent catheter ablation of atrial fibrillation or left-sided atrioventricular accessory pathway.RESULTS:This transseptal approach reached 100.0% success and was succeeded in 98.9% with the first attempt. The first attempt puncture was aborted due to greater resistance to needle advancement or smaller needle curve in six patients. However, the second attempts were all succeeded after the needle curve was reshaped. There was no tamponade and embolism occurred.CONCLUSION:The atrial septum puncture approach using the location of distal CS electrode as important marker and the guidewire for protection when sending outer sheath into left atrium is reliable and safe.

Endocardial autonomic denervation of the left atrium to treat vasovagal syncope: an early experience in humans.

BACKGROUND:Vasovagal syncope (VVS) is the most common cause of recurrent syncope that can be debilitating despite optimal conventional therapy. The aim of this study was to evaluate the feasibility and efficacy of selective endocardial autonomic denervation in left atrium (LA) as an alternative treatment strategy in patients with highly symptomatic VVS.METHODS AND RESULTS:Ten consecutive patients (mean age, 50.4±6.4 years; 7 women) with a medium of 3.5 (range, 2-20) recurrent episodes of VVS during the preceding year and positive head-up tilt testing in whom standard therapies were ineffective or poorly tolerated were enrolled. Ganglionated plexi (GP) in the LA, identified by high-frequency stimulation, was targeted by radiofrequency catheter ablation. The patients were then followed up at 3, 6, 12, 24, and 36 months, including repeated head-up tilt testing and Holter at 3 and 12 months. Radiofrequency energy was applied at the left superior GP in 10 patients, right anterior GP in 5, and left inferior GP in 3, using an 8-mm ablation catheter. Vagal response, defined as transient ventricular asystole, atrioventricular block, or an increase in R-R interval by 50%, was observed during ablation in all GP sites. The end point of procedure was the inhibition of the vagal response at target sites. At 30±16 (range, 13-55) months of follow-up, no patient had any recurrence of syncope and all patients had significant improvement in symptoms, but 5 of 10 patients reported transient prodromes. No complications occurred.CONCLUSIONS:Comprehensive endocardial autonomic denervation of the LA demonstrates the feasibility of treating VVS in medium-term follow-up.