SVC-RA Junction Research Articles

Voltage-Guided and Non-Voltage-Guided Superior Vena Cava Isolation in Patients With Atrial Fibrillation.

In addition to the pulmonary vein, the superior vena cava (SVC) is an important focus of atrial fibrillation (AF). However, SVC isolation may cause serious complications, and appropriate settings and techniques for SVC isolation are lacking. This study enrolled 86 consecutive patients with AF who underwent SVC isolation. Voltage mapping using a multi-electrode catheter and ablation were performed under the guidance of an electro-anatomical mapping system. The lines encircling the SVC were divided into eight anatomic segments on the SVC geometry, and each segment was subjected to voltage-guided (VG) ablation in decreasing order of voltage (starting from the segment with the highest voltage). Non-VG (NVG) ablation was performed anatomically from the anterior wall toward the septum with one-round cautery. A total of 86 cases (66 males, mean age 69 [60, 74], mean CHA2DS2 VASc score 2 [1, 3], 58 paroxysmal AF) with AF were included for ablation. Electrical SVC isolation was successfully achieved in all patients. The length of the myocardial sleeves, as measured from the SVC-RA junction to the end of the local signal, was 37 [28, 45]mm. Major axis of the RA-SVC junction was 15 [13, 17] and minor axis of the RA-SVC junction was 11 [9, 13]. The number of ablation points with VG SVC isolation was fewer than that for NVG SVC isolation (8 [5, 11.5] vs. 11.5 [8.8, 13.3]; p=0.001). The procedure time of VG SVC isolation was greater than that of NVG SVC isolation (259s [154, 379] vs. 167s [115, 222]; p=0.012). There were no significant differences in the complication rates. VG SVC isolation reduced the number of ablation points compared with NVG SVC isolation.

CARD21: The Effect of Drainage Cannula Design and Tip Position on Thrombosis Risk During Venoarterial Extracorporeal Membrane Oxygenation: A Computational Analysis

Background: Venoarterial extracorporeal membrane oxygenation (VA ECMO) supports critically ill patients with refractory cardiopulmonary failure. Drainage cannulae remove venous blood from the patient, but variability in cannula selection and tip position may impact flow dynamics and thrombosis risk. Therefore, this study investigated the effect of tip position of single-stage (SS) and multi-stage (MS) VA ECMO drainage cannulae on the risk of thrombosis. Methods: Computational fluid dynamics was used to model flow dynamics within a patient-specific geometry of the venae cavae. The tip of the SS and MS cannulae was modelled in the superior vena cava (SVC), SVC-Right atrium (RA) junction, mid-RA, inferior vena cava (IVC)-RA junction, and IVC. Constant mass flow rates were applied at all major vein inlets reflecting normal physiological flows. Drainage flow rates of the cannula were set at a constant 4 L/min throughout all simulations. The risk of thrombosis was assessed by measuring blood residence time, stagnant volume, rate of blood washout, and high wall shear stress. Results: Changes in the tip position of the SS cannula resulted in variability of thrombosis risk, whereas the MS cannula showed similar thrombosis risk during all simulations. The SS cannula showed reduced thrombosis risk arising from stagnant regions when placed in the SVC or SVC-RA junction, whereas an MS cannula was predicted to create stagnant regions during all tip positions (Figure 1). Conversely, the risk of thrombosis was increased in all positions with the SS cannula arising from higher maximum wall shear stresses (Table 1). When positioned in the IVC-RA junction and IVC, the SS cannula exhibited higher risk of thrombosis arising due to both high and low shear, compared to the MS cannula. Conclusion: Tip position of the drainage cannula impacts cannula flow dynamics and, subsequently, the risk of thrombosis. The use of MS cannulae can reduce high shear-related thrombosis, but SS cannulae can eliminate stagnant regions when advanced into the SVC. Therefore, the choice of cannula design and tip position should be carefully considered during cannulation.Figure 1. Comparison of stagnation regions between the single-stage (a) and multi-stage (b) cannulae at varying tip positions.

The effect of drainage cannula tip position on risk of thrombosis during venoarterial extracorporeal membrane oxygenation

Background and objectivesVenoarterial extracorporeal membrane oxygenation (VA ECMO) is able to support critically ill patients undergoing refractory cardiopulmonary failure. It relies on drainage cannulae to extract venous blood from the patient, but cannula features and tip position may impact flow dynamics and thrombosis risk. Therefore, this study aimed to investigate the effect of tip position of single-stage (SS) and multi-stage (MS) VA ECMO drainage cannulae on the risk of thrombosis. MethodsComputational fluid dynamics was used to model flow dynamics within patient-specific geometry of the venous vasculature. The tip of the SS and MS cannula was placed in the superior vena cava (SVC), SVC-Right atrium (RA) junction, mid-RA, inferior vena cava (IVC)-RA junction, and IVC. The risk of thrombosis was assessed by measuring several factors. Blood residence time was measured via an Eulerian approach through the use of a scalar source term. Regions of stagnant volume were recognised by identifying regions of low fluid velocity and shear rate. Rate of blood washout was calculated by patching the domain with a scalar value and measuring the rate of fluid displacement. Lastly, wall shear stress values were determined to provide a qualitative understanding of potential blood trauma. ResultsThrombosis risk varied substantially with position changes of the SS cannula, which was less evident with the MS cannula. The SS cannula showed reduced thrombosis risk arising from stagnant regions when placed in the SVC or SVC-RA junction, whereas an MS cannula was predicted to create stagnant regions during all tip positions. When positioned in the IVC-RA junction or IVC, the risk of thrombosis was higher in the SS cannula than in the MS cannula due to both high and low shear flow. ConclusionTip position of the drainage cannula impacts cannula flow dynamics and, subsequently, the risk of thrombosis. The use of MS cannulae can reduce high shear-related thrombosis, but SS cannulae can eliminate stagnant regions when advanced into the SVC. Therefore, the choice of cannula design and tip position should be carefully considered during cannulation.

Initial experience of a novel method for electrical isolation of the superior vena cava using cryoballoon in patients with atrial fibrillation.

Damage to the sinus node (SN) has been described as a potential complication of superior vena cava (SVC) isolation. There have been reports of permanent SN injury requiring pacemaker implantation during isolation of the SVC. It is safe and effective to isolate SVC with the second-generation 28-mm cryoballoon by using a novel method. Forty-three patients (including six redo cases) with SVC-related atrial fibrillation (AF) from a consecutive series of 650 patients who underwent cryoballoon ablation were included. After pulmonary vein isolation was achieved, if the SVC trigger was identified, the SVC was electrically isolated using the cryoballoon. First, the cryoballoon was inflated in the right atrium (RA) and advanced towards the SVC-RA junction. After total occlusion was confirmed by dye injection with total retention of contrast in the SVC, the SVC-RA junction was determined. Next, the cryoballoon was deflated, advanced into SVC, then reinflated, and pulled back gently. The equatorial band of the cryoballoon was then set slightly (4.32 ± 0.71 mm) above the SVC-RA junction for isolation of the SVC. Real-time SVC potential was observed in all patients during ablation. The mean time to isolation was 24.5 ± 10.7 s. The SVC was successfully isolated in all patients. The mean number of freeze cycles was 2.5 ± 1.4 per patient, and the mean ablation time was 99.8 ± 22.7 s. A transient phrenic nerve (PN) injury occurred in one patient (2.33%). There were no SN injuries. Freedom from AF rates at 6 and 12 months was 97.7% and 93.0%, respectively. This novel method for SVC isolation using the cryoballoon is safe and feasible when the SVC driver during AF is determined and could avoid SN injury. PN function should still be carefully monitored during an SVC isolation procedure.

Evaluation of Surface Landmarks and C-length as Predictors of the Depth of Right Internal Jugular Venous Catheter Insertion: A Transesophageal Echocardiography-Guided Study

Abstract Background Central venous catheterization is a standard clinical practice for infusion of fluids, blood products, or vasoactive drugs to the central circulation and to monitor central venous pressure during perioperative periods. However, this procedure can lead to significant complications, including cardiac arrhythmia, vascular injury, hydrothorax, hemothorax, hydromediastinum, and cardiac tamponade. Such complications can occur when the catheter tip is inserted within the heart chamber or when it abuts the vascular wall at a steep angle. Objectives The primary aim of the current study is to examine the accuracy of the C-distance or surface landmarks in determining the length of CVC that is required to place the catheter tip at the mid-SCV as confirmed by transesophageal echocardiography (TEE). A secondary aim is to derive an equation or formula to calculate the depth of the CVC that is required in order to have the catheter tip placed at the mid-SVC. Patients and Methods After obtaining the approval from research ethical committee of Ain Shams University and obtaining informed consent from patients the study was conducted in The Academic Institute for Cardiothoracic and Vascular Surgery, Ain Shams University hospitals. 30 adult patients scheduled for elective cardiac surgeries were enrolled in the study after being selected by random simple method. Results We used the TEE to visualize the CVC tip 3 cm above SVC-RA junction and use this actual depth to compare between the accuracy of the expected depth by C-length method and expected measured depth by surface landmarks method; we found out that the two methods were nearly the same to the actual depth guided by TEE. The mean ± SD surface landmarks distance was 142 ± 12 mm (range, 120 - 162 mm) and the mean ± SD by C-length was 128 ± 18 mm (range, 95 - 174 mm). The mean ± SD TEE-guided CVC length needed to place CVC tip at mid-SVC was140 ± 13 mm (range, 110 - 162 mm). Also in none of the patients was the CVC tip placed below the carinal level on postoperative plain AP chest x-ray. The CVC tip was placed at a mean ± SD height of 12 ± 2 mm (range, 5 to 16 mm) above the carinal line, which concludes that the mid SVC region lies above the carina level by 0.5-1.5 cm and it’s a reliable landmark for postoperative confirmation of optimum placement of CVC tip. Conclusion TEE can be used to effectively determine the proper fixed catheter insertion depth for a patient through the right internal jugular vein. This study showed that both C-length and surface landmarks methods are accurate to determine the depth of the central venous catheter in the mid SVC region (3-3.5 cm) above SVC-RA junction above pericardial reflection. Another conclusion is that the mid SVC region is above carinal level in all cases by 5 mm -15 mm. From this study we formulated two regression equations depending on the expected surface landmarks and C-length with an accuracy of ± 11.662 mm and ± 10.643 mm respectively.

Correction of Sinus Venosus Atrial Septal defects with the 10 zig covered CP Stent–an International Registry

Covered stent correction of sinus venosus ASDs (SVASD) is a relatively new technique. Challenges include anchoring a sufficiently long stent in a non-stenotic SVC and expanding the stent at the wider SVC-RA junction without obstructing the anomalous right upper pulmonary vein (RUPV). The 10-zig covered CP (CCP) stent has the advantage of being available in lengths of 5–11 cm and dilatable to 34 mm in diameter. An international registry reviewed the outcomes of 10-zig CCP stents in 75 patients aged 11.4–75.9 years (median 45.4) from March 2016. Additional stents were used to anchor the stent in the SVC or close residual shunts in 33/75. An additional stent was placed in 4/5 (80%) with 5/5.5 cm CCPs, 18/29 (62%) with 6 cm CCPs, 5/18 (28%) with 7 cm CCPs, 5/22 (23%) with 7.5/8 cm CCPs and 0/1 with an 11 cm CCP. A “protective” balloon catheter was inflated in the RUPV in 17. Early stent embolisation in two patients required surgical removal and defect repair and tamponade was drained in one patient. The CT at 3 months showed occlusion of the RUPV in one patient. Follow up is from 2 months to 5.1 years (median 1.8 years). QP:QS has reduced from 2.5 + 0.5 to 1.2 + 0.36 ( P < 0.001) and RVEDVi from 149.1 + 35.4 to 95.6 + 21.43 ml/m 2 ( P < 0.001). 10-zig CCPs of 7–8 cm appear to provider reliable SVASD closure with a low requirement for additional stents. Careful selection of patients and meticulous attention to detail is required to avoid complications.

Correction of sinus venosus atrial septal defects with the 10 zig covered Cheatham-platinum stent - An international registry.

Covered stent correction of sinus venosus ASDs (SVASD) is a relatively new technique. Challenges include anchoring a sufficiently long stent in a nonstenotic superior vena cava (SVC) and expanding the stent at the wider SVC-RA junction without obstructing the anomalous right upper pulmonary vein (RUPV). The 10-zig covered Cheatham-platinum (CCP) stent has the advantage of being available in lengths of 5-11 cm and dilatable to 34 mm in diameter. An international registry reviewed the outcomes of 10-zig CCP stents in 75 patients aged 11.4-75.9 years (median 45.4) from March 2016. Additional stents were used to anchor the stent in the SVC or close residual shunts in 33/75. An additional stent was placed in 4/5 (80%) with 5/5.5cm CCPs, 18/29 (62%) with 6cm CCPs, 5/18 (28%) with 7cm CCPs, 5/22 (23%) with 7.5/8cm CCPs and 0/1 with an 11 cm CCP. A "protective" balloon catheter was inflated in the RUPV in 17. Early stent embolization in two patients required surgical removal and defect repair and tamponade was drained in one patient. The CT at 3months showed occlusion of the RUPV in one patient. Follow up is from 2months to 5.1 years (median 1.8 years). QP:QS has reduced from 2.5± 0.5 to 1.2± 0.36 (p < .001) and RVEDVi from 149.1± 35.4 to 95.6± 21.43 ml/m2 (p < .001). Ten-zig CCPs of 7-8cm appear to provide reliable SVASD closure with a low requirement for additional stents. Careful selection of patients and meticulous attention to detail is required to avoid complications.

CT validation of SVC-RA junction location for pediatric central line placement: is vertebral bodies below the carina accurate?

The key landmark for tip position of a central venous catheter (CVC) is the SVC-RA junction. In adults, localization of the SVC-RA junction may be assessed as a function of vertebral body units (VBU) below the carina during CVC placement. We investigated the relationship between the SVC-RA junction and the carina in children. 584 CT scans of 0-18years were analyzed. The carina was marked automatically by software while the SVC-RA junction and vertebrae were marked manually. The SVC-RA junction to carina (JC) distance was the primary study measurement reported in both VBU and mm. The data show an average JC distance of 1.25 VBU for 0-1year, 1.27 VBU for 1-4years, 1.34 VBU for 4-9years, 1.53 VBU for 9-15years, and 1.64 VBU for 15-18years. A positive relationship between weight and JC distance was also demonstrated. JC distance is a useful predictor of SVC-RA junction location in children. Significant relationships were shown between JC distance and both age and weight. Due to small differences between age groups, however, average JC distance for all comers (1.48 VBU, 95% CI 0.7 - 2.3) can be used for SVC-RA junction identification in CVC placement.

Visualization of the electrophysiologically defined junction between the superior vena cava and right atrium.

An electrical superior vena cava (SVC) isolation from the right atrium (RA) sometimes can be challenging. For a safe and efficient SVC isolation, we aimed to visualize the accurate position of the SVC-RA junction on a three-dimensional (3D) mapping system using the decremental conduction properties of the SVC-RA junction in patients with atrial fibrillation (AF). This study consisted of 15 consecutive AF patients (11 males, age 59 ± 10 years). A 3D mapping catheter was positioned in the SVC-RA junction region while delivering a single extra-stimulus from the right atrial appendage (RAA), to discriminate the RA and SVC potentials. The electrophysiological SVC-RA junction was defined as the most proximal points where the SVC potentials were recorded, which were tagged on the 3D mapping system around the SVC-RA junction, where radiofrequency energy applications were applied. Around the SVC-RA junction, 9 ± 2 points were tagged on the 3D mapping system. The highest and lowest SVC-RA junction points were located on the anterior wall and posterior wall, respectively. The difference in the level between the highest and lowest SVC-RA junction points was 16.2 ± 6.3 mm. A successful SVC isolation was obtained in all patients without any complications. The plane of the electrophysiologically defined SVC-RA junction was not perpendicular to the body axis, but slanted due to the anterior side being higher. Recognizing the precise location of the SVC-RA junction would contribute to a safe and efficacious SVC isolation.

Extent of Atrial Deformation in Catheter Ablation of Atrial Fibrillation.

Anatomical atrial distortion during catheter mapping and ablation has not been elucidated in atrial fibrillation (AF) ablation. This study aimed to characterize the regional anatomical distortion in common ablation areas according to different contact forces (CFs) with radiofrequency and cryoballoon catheters.Ten patients underwent distortion mapping with low (5-10 g) and high CFs (10-30 g) at the pulmonary vein (PV) antra, left atrial (LA) roof line, mitral isthmus line, cavotricuspid isthmus line, and superior vena cava (SVC)-right atrial (RA) junction. Fifteen patients underwent distortion mapping with a 28-mm second-generation cryoballoon surrounded by a decapolar catheter at each PV antrum following creating the LA geometry. High CFs distorted the PV antra as compared to low CFs and the extent was greater at the anterior PV aspect, and the catheter was located more inside the PVs. The inflated cryballoon stretched the PV surface in the postero-superior direction in the upper PVs and posterior direction in the lower PVs. High CFs as compared to low CFs distorted the LA roof and cavotricuspid isthmus in the postero-inferior and inferior directions, respectively, but not the mitral isthmus line even with deflectable sheaths. High CFs distended the SVC-RA junction as compared to low CFs, and the extent was greatest at the lateral side and smallest at the antero-septal side.Human atria significantly distend during radiofrequency and cryoballoon ablation, and there are regional heterogeneities of the extent of the distortion. This information might aid operators in performing safe and effective AF ablation procedures.

Safety and efficacy of superior vena cava isolation using the second-generation cryoballoon ablation in a canine model

BackgroundThe safety and efficacy of superior vena cava (SVC) isolation (SVCI) using second-generation cryoballoon (CB) ablation remains unknown. MethodsElectrical isolation of SVC was attempted using the second-generation CB ablation catheter in 14 canines. Ablation duration was randomized to either 90 s (7 canines) or 120 s (7 canines). SVC venography was performed to identify the SVC-right atrium (RA) junction. The 28-mm CB was positioned above SVC-RA junction. Repeat electrophysiological assessment in the live animals was conducted 40–60 days post-ablation, after which animals were euthanized for histological examination. ResultsAcute SVCI was successfully performed in all canines. No significant differences in numbers of freezes (1.7 ± 0.8 vs. 1.5 ± 0.5, p = 0.658), time to isolation (TTI) (24.3 ± 8.1s vs. 22.7 ± 9.0s, p = 0.297), temperature at isolation (−23.4 ± 12.5 °C vs. −21.5 ± 11.1 °C, p = 0.370), and nadir temperature (−51.2 ± 6.2 °C vs. −53.3 ± 7.0 °C, p = 0.195) were observed between the 90-s and 120-s groups. There were no procedural complications except one transient sinus bradycardia in the 120-s group. After ablation, animals survived for 51 ± 5 days. Chronic SVCI was achieved in 6 of 7 (85.7%) SVCs in the 90-s group and 7 of 7 SVCs (100%) in the 120-s group (p = 0.299). Histological analysis revealed that a circumferential transmural lesion was achieved in all isolated SVCs. No sinus node (SN) and phrenic nerve injuries were observed. The minimum distance between ablation lesion and SN was 5.1 ± 3.0 mm. ConclusionsThe second-generation CB ablation catheter is both safe and effective in achieving SVC isolation in a canine model. Effective SVCI was found in the 90-s dosing strategy.

Early experience of transcatheter correction of superior sinus venosus atrial septal defect with partial anomalous pulmonary venous drainage

Superior sinus venosus atrial septal defect (SVASD) is commonly associated with partial anomalous pulmonary venous drainage (PAPVD). We aim to describe the first series of percutaneous SVASD and PAPVD correction using a two-step simulation for procedural planning. Patients with SVASD and right PAPVD with a clinical indication for correction were selected. They underwent an ex vivo procedural simulation on a 3D-printed model followed by an in vivo simulation using balloon inflation in the targeted stent landing zone. The percutaneous procedure consisted in deploying a 10 Zig custom-made covered stent in the SVC-RA junction. Nine patients were referred for pre-procedural evaluation and were deemed suitable for percutaneous correction. The procedure was successful in all patients with no residual interatrial shunt and successful redirection of the pulmonary venous drainage to the left atrium. At a median clinical follow-up of 8.1 months (2.6–19.8), no adverse events were noted and all patients showed clinical improvement. During follow-up, transthoracic echocardiography and MDCT in 4 patients or invasive angiography in one patient demonstrated a patent SVC stent, no residual SVASD and unobstructed PV drainage in all patients. In selected patients using a two-staged simulation strategy, percutaneous correction of SVASD with PAPVD is feasible, safe and led to favorable midterm outcomes.

Early experience of transcatheter correction of superior sinus venosus atrial septal defect with partial anomalous pulmonary venous drainage.

Superior sinus venosus atrial septal defect (SVASD) is commonly associated with partial anomalous pulmonary venous drainage (PAPVD). We aimed to describe the first series of percutaneous SVASD and PAPVD correction using a two-step simulation for procedural planning. Patients with SVASD and right PAPVD with a clinical indication for correction were selected. They underwent an ex vivo procedural simulation on a 3D-printed model followed by an in vivo simulation using balloon inflation in the targeted stent landing zone. The percutaneous procedure consisted in deploying a 10-zig custom-made covered stent in the SVC-RA junction. Five patients were referred for preprocedural evaluation and were deemed suitable for percutaneous correction. The procedure was successful in all patients with no residual interatrial shunt and successful redirection of the pulmonary venous drainage to the left atrium. At a median clinical follow-up of 8.1 months (2.6-19.8), no adverse events were noted, and all patients showed clinical improvement. During follow-up, transthoracic echocardiography and multidetector cardiac tomography in four patients or invasive angiography in one patient demonstrated a patent SVC stent, and no residual SVASD and unobstructed PV drainage in all patients. In selected patients using a two-stage simulation strategy, percutaneous correction of SVASD with PAPVD is feasible and safe, and led to favourable short-term outcomes.

Isolation of the superior vena cava from the right atrial posterior wall: a novel ablation approach.

Superior vena cava (SVC) isolation might be difficult to achieve because of the vicinity of the phrenic nerve (PN) and sinus node. Based on its embryogenesis, we hypothesized the presence of preferential conduction from the right atrial (RA) posterior wall, making it possible to isolate the SVC antrally, sparing its anterior and lateral aspect. This is a descriptive cohort study of 105 consecutive patients in which SVC isolation was obtained with radiofrequency ablation, starting in the septal aspect of the SVC-RA junction and continued posteriorly and inferiorly targeting sites of early activation until electrical isolation was obtained. Acute SVC isolation was achieved in 103 (98%) patients; the mean distance between the site of SVC isolation and the SVC-RA junction was 19.9 ± 5.3 (range 9.7-33.7) mm. During follow-up, 2 (2%) patients developed symptomatic diaphragmatic paralysis due to transient right PN injury; 13 patients underwent a repeat ablation: SVC reconnection was observed in 5 patients, and re-isolation was easily achieved by targeting the corresponding sites of early activation. Superior vena cava isolation can be completed by targeting its septal segment and sites of early activation in the posterior SVC-RA junction and RA posterior wall; this is a feasible alternative ablation strategy in patients in which SVC isolation cannot be completed with the standard approach. The risk of sinus node injury or SVC stenosis are eliminated; PN injury is still possible but can easily be prevented with high-output pacing to exclude a true posterior course of the PN.

Abstract 13447: Superior Vena Cava Isolation From the Right Atrial Posterior Wall: A Case Series

Introduction: Superior vena cava (SVC) isolation is a common ablation strategy to address non-pulmonary vein triggers in patients with paroxysmal and non-paroxysmal AF. SVC isolation with circumferential ablation might be difficult to achieve because of the phrenic nerve (PN) location in its anterolateral aspect. Hypothesis: It is possible to isolate the SVC sparing its anterolateral aspect given the presence of preferential conduction from the posterior wall of the right atrium (RA) to the SVC. Methods: Consecutive patients in which SVC isolation ablating in the RA posterior wall. RF ablation was started in the septal aspect of the SVC-RA junction and it was continued posteriorly-inferiorly in sites of early activation (relative to the SVC) until electrical isolation was obtained. The distance between the SVC-RA junction and the site of SVC isolation was measured with 3D electro-anatomical mapping. Results: 85 patients were included in the analysis. 27% were females, with a mean age of 66 ± 10 years, 21% had paroxysmal AF, 42% persistent AF, 36% longstanding persistent AF. The procedure was a repeat ablation in 58% of the cases, with a mean procedure time of 124 ± 38 minutes. Acute SVC isolation was achieved in 98%. Mean distance of isolation from the SVC-RA junction was 19.9 ± 5.1 mm (range 10.2-32.1 mm). At follow-up, we observed 2 (2%) transient PN injuries. After this, we began performing PN mapping in the PW, which precluded complete SVC isolation in 1 case (see Figure 2). Conclusions: SVC isolation can be achieved without circumferential ablation by targeting sites with early activation (relative to the SVC) in the RA posterior wall.

Real-Time MRI-Guided Cardiac Cryo-Ablation: A Feasibility Study.

MRI-based ablation provides an attractive capability of seeing ablation-related tissue changes in real time. Here we describe a real-time MRI-based cardiac cryo-ablation system. Studies were performed in canine model (n = 4) using MR-compatible cryo-ablation devices built for animal use: focal cryo-catheter with 8 mm tip and 28 mm diameter cryo-balloon. The main steps of MRI-guided cardiac cryo-ablation procedure (real-time navigation, confirmation of tip-tissue contact, confirmation of vessel occlusion, real-time monitoring of a freeze zone formation, and intra-procedural assessment of lesions) were validated in a 3 Tesla clinical MRI scanner. The MRI compatible cryo-devices were advanced to the right atrium (RA) and right ventricle (RV) and their position was confirmed by real-time MRI. Specifically, contact between catheter tip and myocardium and occlusion of superior vena cava (SVC) by the balloon was visually validated. Focal cryo-lesions were created in the RV septum. Circumferential ablation of SVC-RA junction with no gaps was achieved using the cryo-balloon. Real-time visualization of freeze zone formation was achieved in all studies when lesions were successfully created. The ablations and presence of collateral damage were confirmed by T1-weighted and late gadolinium enhancement MRI and gross pathological examination. This study confirms the feasibility of a MRI-based cryo-ablation system in performing cardiac ablation procedures. The system allows real-time catheter navigation, confirmation of catheter tip-tissue contact, validation of vessel occlusion by cryo-balloon, real-time monitoring of a freeze zone formation, and intra-procedural assessment of ablations including collateral damage.

Accuracy of Intravenous Electrocardiography Confirmation of Peripherally Inserted Central Catheter for Parenteral Nutrition.

Parenteral nutrition (PN) is a life-saving therapy for patients with intestinal failure. Safe delivery of hyperosmotic solution requires a central venous catheter (CVC) with tip in the lower superior vena cava (SVC) or at the SVC-right atrium (RA) junction. To reduce cost and delay in use of CVC, new techniques such as intravascular electrocardiogram (ECG) are being used for tip confirmation in place of chest x-ray (CXR). The present study assessed for accuracy of ECG confirmation in home PN (HPN). Records for all patients consulted for HPN from December 17, 2014, to June 16, 2015, were reviewed for patient demographics, diagnosis leading to HPN initiation, and ECG and CXR confirmation. CXRs were subsequently reviewed by a radiologist to reassess location of the CVC tip and identify those that should be adjusted. Seventy-three patients were eligible, and after assessment for research authorization and postplacement CXR, 17 patients (30% male) with an age of 54 ± 14 years were reviewed. In all patients, postplacement intravascular ECG reading stated tip in the SVC. However, based on CXR, the location of the catheter tip was satisfactory (low SVC or SVC-RA junction) in 10 of 17 patients (59%). Due to the high osmolality of PN, CVC tip location is of paramount importance. After radiology review of CXR, we noted that 7 of 17 (41%) peripherally inserted central catheter lines were in an unsatisfactory position despite ECG confirmation. With current data available, intravenous ECG confirmation should not be used as the sole source of tip confirmation in patients receiving HPN.

Early result of patients undergoing transcatheter completion of Fontan and Fenestrated extracardiac Fontan

Introduction Fontan surgery and its modifications are well-recognized palliation for univentricular types of heart lesions. Nowadays palliation can be achieved by combined surgical and transcatheter approaches, which offer good immediate and early results for the high-risk patients. Method Between September 2006 through January 2012, 18 patients underwent transcatheter completion of Fontan (gp 1), 28 patients underwent surgical fenestrated extracardiac Fontan (gp 2). GP 1: patients were ventelated and angiogram and hemodynamic assessment followed by opening of the SVC-RA junction and fdevice closure of the ASD II, some with use of covered stent. GP 2: extracardiac Fontan is done with Fenetration by single Surgeon. Result Mean age 4.8 year for (gp1), 3.5 year for (gp2) mean weight is 20 kg& 14 kg respectively, median median sat is 95% and 88% ( p 0.07) , median pulmonary artery pressure is 15 mmhg and 12 mmhg , hospital stay is 2 days and 13 days ( p 0.05) ,7 patients has pleural effusion and 7 has atrial tachy cardia from gp 2 none from gp 1, median follow up 4.8 year. Conclusion We conclude that Trans catheter completion of Fontan approach in selected patient is safe and considered an alternative approach.

Conduction Recovery After Electrical Isolation of Superior Vena Cava

Superior vena cava (SVC) is an infrequent yet an important source of atrial fibrillation (AF). The data on SVC reconnection are limited. Following pulmonary vein (PV) antrum isolation for AF, SVC isolation was systemically performed under angiographic and mapping guidance using 4-mm non-irrigated tip catheter. SVC reconnection could be evaluated in 76 consecutive patients (65 ± 9 years, 59 male) who underwent repeat AF ablation after 16 ± 16 months. SVC was isolated at the 1(st), 2(nd), 3(rd) and 4(th) AF ablation procedure in 63, 7, 5 and 1 patient by 7.3 ± 3.1 radiofrequency applications. SVC reconnection was observed in 56 patients (74%). In the majority, the conduction gap was located at the anterolateral SVC-right atrium (RA) junction. After re-isolation of SVC, 2/7 patients (29%) had reconnection at the following procedure. Among 63 patients who underwent PV and SVC isolation at the initial procedure, the prevalence of reconnection for PV and that for SVC were similar (53/63, 84% vs. 46/63, 73%; P=0.129). Dissociated activity, however, was more frequently observed in the PVs than in the SVC (47/63, 73% vs. 10/63, 16%; P<0.0001). During the procedure, AF initiation from a thoracic vein was identified in 19/63 patients (30%). SVC reconnection is common after 1 or more previous isolation procedures undertaken for AF ablation. Its prevalence is similar to that of PV reconnection. The location of the conduction gap varies widely but is most frequently found at the anterolateral SVC-RA junction.

Chronic Amiodarone Therapy Impairs the Function of the Superior Sinoatrial Node in Patients With Atrial Fibrillation

The mechanisms underlying amiodarone-induced sinoatrial node (SAN) dysfunction remain unclear, so we used 3-dimensional endocardial mapping of the right atrium (RA) to investigate. In a matched-cohort design, 18 patients taking amiodarone before atrial fibrillation (AF) ablation (amiodarone group) were matched for age, sex and type of AF with 18 patients who had undergone AF ablation without taking amiodarone (no-amiodarone group). The amiodarone group had a slower heart rate than the no-amiodarone group at baseline and during isoproterenol infusion. Only the amiodarone group had sick sinus syndrome (n=4, 22%, P=0.03) and abnormal (>550ms) corrected SAN recovery time (n=5, 29%; P=0.02). The median distance from the junction of the superior vena cava (SVC) and RA to the most cranial earliest activation site (EAS) was longer in the amiodarone group than in the no-amiodarone group at baseline (20.5 vs. 10.6mm, P=0.04) and during isoproterenol infusion (12.8 vs. 6.3mm, P=0.03). The distance from the SVC-RA junction to the EAS negatively correlated with the P-wave amplitudes of leads II (r=-0.47), III (r=-0.60) and aVF (r=-0.56) (P<0.001 for all). In a quarter of the AF patients, amiodarone causes superior SAN dysfunction, which results in a downward shift of the EAS and reduced P-wave amplitude in leads II, III and aVF at baseline and during isoproterenol infusion.