Superior Vena Cava-right Atrial Junction Research Articles

Catheter-related atrial thrombosis: prevalence and risk factors in the pediatric age group—a retrospective study

BackgroundCatheter-related right atrial thrombosis (CRAT) is an under-studied complication of a long-term implantable venous access devices (IVAD), particularly in children with incidence rates extrapolated from the adult literature ranging between 2 and 29%. This is a single-center retrospective review of electronic medical records of children who underwent insertion of IVADs and had at least one echocardiogram performed prior to catheter removal between 2008 and 2018. Data collection included demographic information, development of CRAT, systemic infection, and administration of thrombogenic chemotherapeutic agents. We identified six patients who developed CRAT and compared them to 120 control patients. We also performed a detailed chart review for the patients who developed CRAT. Data was entered and analyzed using SPSS.ResultsA total of 764 patients underwent IVAD placement between 2008 and 2018. Six (0.79%) patients developed CRAT, and 120 patients were identified as controls that match the CRAT patients based on definitive criteria that include age, gender, chemotherapy type, steroid therapy, reason of line insertion, site of catheter insertion, tip-location at insertion, and history of systemic infections. In the CRAT group, 3 (50%) patients had their catheter tips placed in the superior vena cava-right atrial junction and 3 (50%) in the right atrium, whereas in the control group, all patients had their catheter tips placed in the superior vena cava-right atrial junction (p=0.000). Five (83.3%) patients in the CRAT group received L-asparaginase as compared to 75 (62.5%) patients in the control group (p=0.301). In the CRAT group, all patients had a history of systemic infection compared to 47 (39.2%) in the control group (p=0.180).ConclusionWe identified 6 (0.79%) children with CRAT. Catheter-tip location within the right atrium is a potential risk factor for CRAT development in children.

Comparison of phrenic nerve injury and its effect on the extrapulmonary vein structures with cryoballoon and hot-balloon ablation systems: considering the lesion created on the superior vena cava as a surrogate marker.

Preventing phrenic nerve injury (PNI) during balloon-based ablation is essential. The superior vena cava-right atrial (SVC-RA) junction is located just opposite the balloon position during right superior pulmonary vein (RSPV) ablation, and the phrenic nerve runs nearby on the lateral side. We compared the occurrence of PNI between the two balloon-based ablation systems and also the lesions created at the SVC-RA junction, which were expected to represent the effect on extra-PV structures. Cryoballoon ablation (CBA, n = 110) and hot-balloon ablation (HBA, n = 90) were performed in atrial fibrillation patients. High-density maps of the SVC-RA junction were created in 93 patients (CBA = 53, HBA = 40), and the damaged area (< 1.0mV) was determined as an "SVC lesion". CBA had a higher occurrence of transient PNI (7.3% vs 1.1%, p = 0.035), but all recovered during the 6-month follow-up. An apparent SVC lesion was documented in 43% of the patients (40/93), and all patients with PNI had this lesion. CBA created a frequent (CBA vs HBA = 55% vs 28%, p = 0.008) and wider (0.8[0.4-1.7] cm2 vs 0.5[0.3-0.7] cm2, p = 0.005) SVC lesion than HBA. A multivariate analysis revealed that the use of a CBA system was a predictive factor of the occurrence of SVC lesions. CBA had a higher occurrence of transient PNI but not a permanent form. Every patient with PNI had lesions on the SVC-RA junction, and CBA revealed more substantial ablation effects at the SVC-RA junction than HBA. This may be caused by the different characteristics of the two balloon-based ablation systems and their balloon positions.

Superior vena cava-right atrium junction flow-pattern post-transcatheter closure of patent foramen ovale.

The patent foramen ovale (PFO) occluder is a bulky metallic device. Its impact on the normal blood flow at the superior vena cava-right atrial (SVC-RA) junction is not clear. We examined SVC-RA junction flow-pattern using pulsed-wave (PW) ultrasound Doppler in 21 patients (4 male, aged 52.7±9years) who underwent PFO device closure 4-120months previously, in comparison with 21 age- and sex-matched controls (4 male, aged 51±8.5years) with structurally normal hearts. Mean systolic flow velocity at the SVC-RA junction was 60±11cm/s in the PFO closure group and 64±17cm/s in the control group (P=0.27). Mean diastolic blood flow velocity at the SVC-RA junction in those groups was 30±8 and 35±9cm/s, respectively (P=0.1).The mean systolic wave duration was 439±52ms in the PFO closure group and 422±67ms in the control group (P=0.4). The mean diastolic wave duration was 320±75 and 277±88ms, respectively (P=0.12). The study results show that transcatheter PFO closure does not affect the normal blood flow at the SVC-RA junction.

Endovascular retrieval of fractured chemoport at the superior vena cava-right atrial junction in 3 years old

A 3-year-old female child, a case of lymphoid leukemia successfully completed her last cycle of chemotherapy. While retrieving the chemoport, the distal part of the port was fractured and migrated distally in the superior vena cava which was seen on the chest radiograph and later confirmed on computed tomography (scan). We present an interesting case where removal of such a fractured port segment was done in toto by means of endovascular intervention through the common femoral vein under fluoroscopy guidance.

Clinical Trial End Points for Hemodialysis Vascular Access: Background, Rationale, and Definitions.

Hemodialysis vascular access is the “lifeline” for patients on hemodialysis. Unfortunately, because of its poor patency and significant complication rate, it is also the “Achilles heel” of hemodialysis. For example, the current unassisted arteriovenous fistula (AVF) maturation rate is only

Abstract PR280

Background & Objectives: Central venous catheters (CVCs) are necessary for pediatric cardiac anesthesia, and malposition of these can lead to various complications (e.g., cardiac perforation, cardiac tamponade, inaccurate central venous pressure). The CVC tip should ideally be placed above the superior vena cava-right atrial junction. However, positioning the CVC tip properly, especially in small children, is difficult. We assumed that the puncture site (lower or higher part of the neck) affects depth of CVC, especially in infants. So, we examined the distance from puncture site to inferior border of clavicle as an anatomic landmark for determining the optimal CVC depth in infants. Materials & Methods: Consecutive infants in whom central catheters were inserted in the right internal jugular vein from December 2012 to November 2015 were evaluated retrospectively. After obtaining hospital IRB approval and informed consent, 32 infants undergoing surgery for congenital heart disease were enrolled in this study. Central venous catheterization was performed under real-time echo guidance. The distance between the insertion point of needle and inferior border of clavicle was measured perpendicularly using a sterile disposable ruler. The insertion depth of CVC was determined by adding 1-2 cm to the distance from the puncture site to inferior border clavicle depending on the patients’ physique. The longitudinal distance between the carina and the CVC tip was measured using chest radiography. We determined the ideal position of the tip of CVC was 1 cm above the carina, as the carina is 0.2-1.0 cm above the pericardial reflection in small children1). For ideal insertion depth of CVC, we calculated the difference between actual and ideal CVC tip position. Demographic data are presented as median (range). Simple linear regression analysis was performed using the least-squares method. Results: The median (range) demographics are as follows: age, 4 months (2 days-11 months); height 61 cm (40-71 cm); weight, 5.6 kg (2-8.4 kg). The optimal insertion depth of CVC showed higher correlation with distance from skin puncture site to the inferior border of the clavicle (r = 0.83 than the patient’s height (r = 0.48) and weight (r = 0.47). According to our results, insertion depth could be predicted using the formula: insertion depth (mm) = 14.4 + 0.96 × (distance from puncture site to inferior border clavicle) Conclusion: We determined that the distance between the insertion point of needle and inferior border of clavicle is useful to determine appropriate insertion depth of CVC in infants and is a practical surface landmark for determining the insertion depth of CVC in infants.

Effect of vagotomy on the activity of cardiac autonomic ganglia: Insight from left atrial high density frequency mapping

BackgroundBoth extrinsic and intrinsic cardiac autonomic nervous systems are important for initiation and maintenance of atrial fibrillation (AF). We aimed to evaluate the effect of vagotomy on the activity of cardiac autonomic ganglionated plexi (GP) and the change of dominant frequency (DF) distribution in the left atrium (LA) during AF. MethodsA mid-sternal thoracotomy was performed in 6 dogs. High frequency stimulation was applied to locate the GPs. There were four major LA GPs, which were located near the pulmonary vein ostia, and a superior vena cava-aorta (SVC-Ao) GP that was located near the superior vena cava-right atrial junction. Acetylcholine patch was applied on GPs to induce intrinsic vagal response. Vagal denervation was performed thereafter. An Ensite Array was deployed in the LA to record atrial signals before and after vagotomy during induced AF. ResultsThe LA mean DF values (8.2±0.1 vs. 7.6±0.1Hz, p=0.002) were higher during GP activation before than after vagotomy. The maximal DF distribution was located at the primary GPs and the nearby secondary GPs during LA GPs activation and at the LA septum and right superior pulmonary vein during SVC-Ao GP activation before vagotomy. After vagotomy, the maximal DF distribution shifted to non-GP LA sites during activation of the GPs. ConclusionsThe findings suggest the important role of the extrinsic neural input in the activation and interaction of the intrinsic cardiac autonomic activity during cholinergic AF, whereas the non-GP LA sites were responsible for the AF induced without the physiological extrinsic neural input.

Endovascular Treatment of Superior Vena Cava Obstruction After Surgical Correction of Intracardiac Total Anomalous Pulmonary Venous Connection

A three-month-old infant operated for obstructed intracardiac total anomalous pulmonary venous connection was readmitted because of sinus bradycardia and superior vena cava syndrome. Cardiac catheterization revealed a stenosis at the superior vena cava-right atrial junction with retrograde azygos flow. Following balloon dilatation of the stenotic area and stent implantation, the superior vena cava syndrome was rapidly relieved. At six months, an echocardiogram confirmed unobstructed flow from the superior vena cava to the right atrium.

Measurement of Length between Bronchial Carina and Superior Vena Cava-right Atrial Junction for Optimal Positioning of Central Venous Catheters in the Korean Adult Population

Measurement of Length between Bronchial Carina and Superior Vena Cava-right Atrial Junction for Optimal Positioning of Central Venous Catheters in the Korean Adult Population

Abstract 9133: Abnormal Response of Superior Sinoatrial Node to Sympathetic Stimulation is a Characteristic Finding in Patients with Atrial Fibrillation and Symptomatic Bradycardia

Introduction: We hypothesize that unresponsiveness of superior sinoatrial node (SAN) to sympathetic stimulation is strongly associated with the development of symptomatic bradycardia in patients with atrial fibrillation (AF). Methods and Results: We performed 3-dimensional endocardial mapping in healthy control (Group 1, n=10) and in patients with AF without (Group 2, n=57) or with (Group 3, n=15) symptomatic bradycardia at baseline and during isoproterenol infusion. Sympatomatic bradycardia includes cardiac syncope, presyncope or dizziness associated with either sinus bradycardia (&lt;40 bpm; n=7) or prolonged sinus pauses (&gt;3.0 seconds; n=8) Corrected SAN recovery time (CSNRT) was abnormal (&gt; 550ms) in 0%, 11% and 36% of groups 1, 2 and 3, respectively (p=0.02). At baseline, 90%, 36% and 7% (p&lt;0.001) of the patients had multicentric SAN activation patterns. For groups 1, 2 and 3, respectively, the median distance from the superior vena cava-right atrial junction to the most cranial earliest activation site (EAS) was 5.0 (25-75 percentile range, 3.5-21.3) mm, 10.0 (4-20) mm and 17.5 (12-34) mm at baseline (p=0.01), and was 4.0 (0-5) mm, 5.0 (1-10) mm and 15.0 (5.4-33.3) mm during isoproterenol infusion (p=0.01), suggesting upward shift of EAS during isoproterenol infusion. However, while the EAS during isoproterenol infusion was at the upper 1/3 of crista terminalis in 100% of Group 1 and 78% of Group 2 patients, only 20% of the groups 3 patients moved EAS to that region (p &lt; 0.001). We analyzed the comparative efficacy of CSNRT and 3D mapping in differentiating Group 2 and Group 3 patients. The sensitivity and specificity of CSNRT test are 35% and 89%, respectively, and of the 3D mapping test are 78% and 78%, respectively. Conclusions: Superior SAN serves as the EAS during sympathetic stimulation in normal patients and in most patients with AF without symptomatic bradycardia. In contrast, unresponsiveness of superior SAN to sympathetic stimulation is a characteristic finding in patients with AF and symptomatic bradycardia.

Abnormal Response of Superior Sinoatrial Node to Sympathetic Stimulation Is a Characteristic Finding in Patients With Atrial Fibrillation and Symptomatic Bradycardia

We hypothesized that unresponsiveness of superior sinoatrial node (SAN) to sympathetic stimulation is strongly associated with the development of symptomatic bradycardia in patients with atrial fibrillation (AF). We performed 3D endocardial mapping in healthy controls (group 1, n=10) and patients with AF without (group 2, n=57) or with (group 3, n=15) symptomatic bradycardia at baseline and during isoproterenol infusion. Corrected SAN recovery time was abnormal in 0%, 11%, and 36% of groups 1, 2, and 3, respectively (P=0.02). At baseline, 90%, 26%, and 7% (P<0.001) of the patients had multicentric SAN activation patterns. For groups 1, 2, and 3, the median distance from the superior vena cava-right atrial junction to the most cranial earliest activation site (EAS) was 5.0 (25-75 percentile range, 3.5-21.3), 10.0 (4-20), and 17.5 (12-34) mm at baseline (P=0.01), respectively, and 4.0 (0-5), 5.0 (1-10), and 15.0 (5.4-33.3) mm, respectively, during isoproterenol infusion (P=0.01), suggesting an upward shift of EAS during isoproterenol infusion. However, although the EAS during isoproterenol infusion was at the upper one third of the crista terminalis in 100% of group 1 and 78% of group 2 patients, only 20% of group 3 patients showed a move of the EAS to that region (P<0.001). Superior SAN serves as the EAS during sympathetic stimulation in patients without AF and in most patients with AF without symptomatic bradycardia. In contrast, unresponsiveness of superior SAN to sympathetic stimulation is a characteristic finding in patients with AF and symptomatic bradycardia.

High‐Density Mapping of the Sinus Node in Humans: Role of Preferential Pathways and the Effect of Remodeling

The area of the functional sinus node complex exceeds that of the anatomical sinus node; however, reasons for this discrepancy are unknown. We aimed to characterize the functional sinus node complex in health and disease with high-density simultaneous mapping. Sinus node activity was characterized in 15 reference patients after ablation for supraventricular tachycardia. A further 16 patients were studied following ablation of chronic atrial flutter to determine effects of atrial remodeling. High-density simultaneous mapping of the sinus node complex was performed using a multi-electrode array. In reference patients, distance from superior vena cava-right atrial (SVC-RA) junction to earliest activation (EA) was 4 +/- 4 mm and sinus break-out (SBO) 9 +/- 6 mm. Preferential pathways of conduction were observed between EA and SBO. For patients with flutter, these distances were greater (EA: 15 +/- 12 mm, P = 0.003; SBO: 23 +/- 11 mm, P < 0.001). Conduction time along preferential pathways was 15 +/- 5 ms for reference patients and 23 +/- 8 ms for patients with flutter (P = 0.005). Following pacing, distance from SVC-RA junction to EA and SBO lengthened to 13 +/- 8 mm (P = 0.006) and 16 +/- 10 mm (P = 0.02), respectively, in reference patients, and 19 +/- 12 mm (P = 0.045), 28 +/- 9 mm (P = 0.02) in patients with flutter. This resulted in caudal shifts in EA and SBO of 10 +/- 9 mm and 7 +/- 8 mm in reference patients but diminished shifts in patients with flutter; 4 +/- 7 mm and 4 +/- 6 mm. The functional sinus node complex demonstrates dynamic changes in activation. There are preferential pathways of conduction from sinus node to atrial myocardium. The remodeled atria demonstrate longer conduction times along preferential pathways and a restricted functional sinus node complex.

Intravenous electrocardiographic guidance for placement of peripherally inserted central catheters

Background Correct positioning of peripherally inserted central catheters (PICCs) is essential to avoid complications. We evaluated intravenous electrocardiogram (ECG) recordings during PICC placement to assess the effectiveness of this guidance technique to reduce complications resulting from incorrect catheter placement. Methods Six patients undergoing PowerPICC catheter insertion were included in this pilot study. Venography through the PICC was performed to identify the superior vena cava–right atrial (SVC-RA) junction. Unipolar ECG recordings from the catheter stylet measured P-wave changes during PICC insertion. Results The peak P-wave amplitude was highest at the SVC-RA junction. With catheter insertion into the RA, P-wave amplitude decreased and eventually became negative. With catheter withdrawal into the SVC, P-wave amplitude decreased. Conclusions P-wave amplitude was highest when the PICC catheter was in the optimal location at the SVC-RA junction. Intravenous ECG monitoring during PICC insertion seems to be a promising technique to guide catheter positioning.

Dual Inferior Venae Cavae with Mitral Stenosis

A 34-year old woman with rheumatic mitral stenosis was found to have complete dual inferior venae cavae with bilateral infrarenal and suprarenal segments, on balloon mitral valvuloplasty. The bilateral, renal, and gonadal veins drained separately on the ipsilateral side. The left inferior vena cava was larger than the right, and the right inferior vena cava had an aneurysmal dilatation near its origin. The left inferior vena cava drained into the superior vena cava-right atrial junction.

Surgical management and treatment of a traumatic right atrial rupture

We have treated three patients with blunt traumatic right atrial rupture, all of whom survived after an emergent cardiac repair without cardiopulmonary bypass. Cardiac tamponade was seen in two of the three cases on ultrasonographic cardiography (UCG). The site of rupture was the right atrial appendage in two cases and the superior vena cava-right atrial (SVC-RA) junction in one case. Hemostasis had been obtained at the time of pericardiotomy because of compression by hematoma. Some patients with a right atrial rupture respond to initial volume resuscitation. Suspecting some cardiac injuries in patients with traumatic pericardial effusion on UCG, a patient with a right atrial rupture can survive with a high probability, without the use of cardiopulmonary bypass.

Persistent Fever, Mediastinal Mass in a 5-year-old Boy

&lt;P&gt;This 5-year-old boy was transferred from an outside hospital for evaluation of persistent fever and a mediastinal mass. He was in his usual state of good health until 2 days prior to admission, when he developed fever, abdominal pain, chest pain, vomiting, and diarrhea. There were no complaints of dyspnea, cough, orthopnea, or fatigue. He was admitted to an outside hospital for treatment of gastroenteritis and dehydration. At the time of admission, laboratory findings included hemoglobin 7.2 g/dL, MCV 59, white blood cell count 13,000/mm&lt;sup&gt;3&lt;/sup&gt; with 71% polymorphonuclear cells, 21% lymphocytes, 7% monocytes; platelet count 160,000/mm&lt;sup&gt;3&lt;/sup&gt;. Because of the microcytic anemia, a lead level was obtained, which was 32 mcg/dL. While looking for lead chips in the abdomen, x-ray revealed a left lower lobe infiltrate. Two days later, a chest x-ray demonstrated cardiomegaly. This finding prompted echocardiography, which revealed a moderate to severe circumferential pericardial effusion. Ultimately, 220 cc of serosanguineous pericardial fluid was removed. The cell count had 70,000 red blood cells, 3,000 white blood cells that were 70% neutrophils, and 12% lymphocytes. Acid-fast bacterial stains were negative. The pericardial fluid glucose was 76 mg/dL, and protein was 5 g/dL. The pericardial fluid culture was negative. Several days later, follow-up echocardiogram revealed an echogenic density in the wall of the right atrium at the superior vena cava-right atrial junction. A cardiac magnetic resonance image (MRI) demonstrated a 6.5 × 3.0 cm mass in the pericardial space, abutting the anterolateral aspect of the right atrium.&lt;/P&gt; &lt;H4&gt;Key Learning Points&lt;/H4&gt; &lt;OL&gt; &lt;LI&gt;Anemia of chronic inflammation is generally normocytic, but may be microcytic at times.&lt;/LI&gt; &lt;LI&gt;The normal age groups in which iron deficiency is seen are between 9 to 24 months and in the early teenage years, particularly in menstruating young women. Outside these age ranges, physicians must consider an alternate etiology of iron deficiency, such as occult gastrointestinal blood loss or iron malabsorption.&lt;/LI&gt; &lt;LI&gt;Immune myofibroblastic tumors are a spectrum of proliferative lesions that range from a benign, reactive process to a true malignancy. They often present with high fevers and refractory anemia as a result of prostaglandin release.&lt;/LI&gt; &lt;/OL&gt; &lt;H4&gt;ABOUT THE AUTHOR&lt;/H4&gt; &lt;P&gt;Dr. Listernick is Professor of Pediatrics at Feinberg School of Medicine, Northwestern University, and Director of the Diagnostic and Consultation Service, Division of General Academic Pediatrics, Children’s Memorial Hospital, Chicago, IL.&lt;/P&gt;

Does the Age Affect the Fluoroscopy‐Guided Transseptal Puncture in Catheter Ablation of Atrial Fibrillation?

The anatomical differences with age may raise difficulty in determining the proper positioning of the transseptal puncture site in the therapeutic left heart catheterization. This study investigated whether age affects the fluoroscopy-guided transseptal puncture in the catheter ablation of atrial fibrillation. Fifty patients (52 +/- 12 years, 35 men) who underwent ablation for paroxysmal/persistent atrial fibrillation were included. The patients were divided into two groups according to their age (cut-point 50 y/o): young group (n = 20) and old group (n = 30). In the 30 degrees right anterior oblique view (RAO), the width between the transseptal puncture site and coronary sinus ostium (H (N-CSO)) was longer in old-age group (14.4 +/- 9.4 vs 10.9 +/- 10.4 mm, P = 0.034). In the 60 degrees left anterior oblique view (LAO) view, the angle of the direction of the transseptal needle (N-angle) was less in the old-age group (56.0 +/- 10.0 degrees vs 58.4 +/- 9.8 degrees , P = 0.041). The ratio of the transseptal puncture site-coronary sinus ostium (CSO) distance over the distance between the superior vena cava-right atrial junction and CSO (V(N-CSO)/V(J-CSO)) was significantly higher in the old-age group (0.73 +/- 0.12 vs 0.63 +/- 0.2, P = 0.009). The transseptal puncture site in the RAO view moved higher and more posterior and the transseptal puncture angle in the LAO view decreased with age. These findings highlight the influence of age on the atrial anatomy and transseptal puncture site.

Electrophysiological and Histological Evaluation of Acute Efficacy and Safety of Balloon Occlusive Ablation at Superior Vena Cava-Right Atrial Junction

We evaluated efficacy and safety of occlusive radiofrequency catheter ablation (o‐RFA) using our thermal balloon catheter (TBC) at superior vena cava (SVC)‐right atrial (RA) junction (SVCJ) compared to that of RFA with a standard‐tip catheter. Methods: To electrically isolate (SVCI) SVC from RA in 10 pigs (group 1), the initial o‐RFA at a balloon surface temperature of 53.9 ± 3.0°C for 3–5 min (13.56 MHz) was achieved at the SVCJ completely obstructed with an inflated balloon. If unsuccessful, subsequent o‐RFA was repeated in a ࣘ5°C increments until reaching either SVCI or sinus arrest. Before and after each o‐RFA, stimulation protocol from the RA was performed. Additionally, in 5 different pigs (group 2), RFA at 55°C (ࣘ50 W) for 1 min with a 4 mm‐tip catheter was achieved at multiple sites along the SVCJ. Finally, the neighboring tissues of the SVCJ were histologically investigated. Results: In group 1, successful SVCI could be easily accomplished at the final temperature of 57.2 ± 2.4°C; however, in 3 pigs, a new atrial tachycardia was induced after o‐RFA at &lt;55°C and in 2 pigs sinus arrest occurred during o‐RFA at 60°C. Histologically, transmural and circumferential contraction band necrosis was mainly confirmed around the SVCJ without damage to collateral tissue. In group 2, coagulation necrosis occupied almost all the ablative lesions, leading to severe degeneration of collateral tissue. Conclusion: O‐RFA at the SVCJ may be more feasible and safer than RFA.

Electrophysiological and Histological Evaluation of Acute Efficacy and Safety of Balloon Occlusive Ablation at Superior Vena Cava-Right Atrial Junction

We evaluated efficacy and safety of occlusive radiofrequency catheter ablation (o-RFA) using our thermal balloon catheter (TBC) at superior vena cava (SVC)-right atrial (RA) junction (SVCJ) compared to that of RFA with a standard-tip catheter. Methods: To electrically isolate (SVCI) SVC from RA in 10 pigs (group 1), the initial o-RFA at a balloon surface temperature of 53.9 ± 3.0°C for 3–5 min (13.56 MHz) was achieved at the SVCJ completely obstructed with an inflated balloon. If unsuccessful, subsequent o-RFA was repeated in a ࣘ5°C increments until reaching either SVCI or sinus arrest. Before and after each o-RFA, stimulation protocol from the RA was performed. Additionally, in 5 different pigs (group 2), RFA at 55°C (ࣘ50 W) for 1 min with a 4 mm-tip catheter was achieved at multiple sites along the SVCJ. Finally, the neighboring tissues of the SVCJ were histologically investigated. Results: In group 1, successful SVCI could be easily accomplished at the final temperature of 57.2 ± 2.4°C; however, in 3 pigs, a new atrial tachycardia was induced after o-RFA at <55°C and in 2 pigs sinus arrest occurred during o-RFA at 60°C. Histologically, transmural and circumferential contraction band necrosis was mainly confirmed around the SVCJ without damage to collateral tissue. In group 2, coagulation necrosis occupied almost all the ablative lesions, leading to severe degeneration of collateral tissue. Conclusion: O-RFA at the SVCJ may be more feasible and safer than RFA.

Intra- and Extra-pericardial Lengths of the Superior Vena Cava in Vivo: Implication for the Positioning of Central Venous Catheters

To reduce the possibility of cardiac tamponade, a rare but lethal complication of central venous catheters, the tip of the central venous catheter should be located above the cephalic limit of the pericardial reflection, not only above the superior vena cava-right atrium junction. This study was performed to measure the superior vena cava lengths above and below the pericardial reflection in cardiac surgical patients. Cardiac surgical patients (n = 61; 27 male), whose age [mean +/- SD (range)] was 47 +/- 15 (15-75) years, were studied. The intrapericardial and extrapericardial lengths, and the length of the medial duplicated part were measured separately. The whole vertical lengths of the superior vena cava on either side were calculated respectively by adding the intra-and extrapericardial and medial duplication lengths. The lateral extrapericardial was 29.1 +/- 6.5 (Mean +/- SD) (9-49) mm (range), and lateral extrapericardial length was 32.6 +/- 6.9 (20-53) mm. The medial extrapericardial length was 23.3 +/- 5.0 (11-39) mm, medical duplicated length was 7.2 +/- 3.3 (4-20) mm, and medial intrapericardial was 28.3 +/- 7.0 (20-52) mm. The averaged superior vena cava length of both sides was 60.3 +/- 9.0 (44.5-90) mm. Almost half of the superior vena cava was found to be within the pericardium and half out. This information may be helpful in deciding how far a central venous catheter should be withdrawn beyond the superior vena cava-right atrial junction during right atrial electrocardiographic guided insertion, and in the prediction of optimal central venous catheter insertion depth.