Distance-dependent neuromodulation effect during thermal ablation for atrial fibrillation.

INTRODUCTION: Thermal atrial fibrillation (AF) ablation exerts an additive treatment effect on the cardiac autonomic nervous system (CANS). This effect is mainly reported during ablation of the right superior pulmonary vein (RSPV), modulating the right anterior ganglionated plexus (RAGP), which contains parasympathetic innervation to the sinoatrial node in the epicardial fat pad between RSPV and superior vena cava (SVC). However, a variable response to neuromodulation after ablation is observed, with little to no effect in some patients. Our objective was to assess clinical and anatomic predictors of thermal ablation-induced CANS changes, as assessed via variations in heart rate (HR) postablation. METHODS: Consecutive paroxysmal AF patients undergoing first-time PV isolation by the cryoballoon (CB) or radiofrequency balloon (RFB) within a 12-month time frame and with preprocedural cardiac computed tomography (CT), were evaluated. Preablation and 24-h postablation electrocardiograms in sinus rhythm were collected and analyzed to assess HR. Anatomic evaluation by CT included the measurement of the shortest distance between the SVC and RSPV ostium (RSPV-SVC distance). RESULTS: A total of 97 patients (CB, n = 50 vs. RFB, n = 47) were included, with similar baseline characteristics between both groups. A significant HR increase postablation (ΔHR ≥ 15 bpm) occurred in a total of 37 patients (38.1%), without difference in number of patients between both thermal ablation technologies (CB, 19 [51%]), RFB, 18 [49%]). Independent predictors for increased HR were RSPV-SVC distance (odds ratio [OR]: 0.49, CI: 0.34-0.71, p value < .001), and age (OR: 0.94, CI: 0.89-0.98, p value = .003). CONCLUSIONS: Thermal balloon-based PV isolation influences the CANS through its effect on the RAGP, especially in younger patients and patients with shorter RSPV-SVC distance.

High Output Cardiovascular Physiology and Outcomes in Fetal Diagnosis of Vein of Galen Malformation.

Vein of Galen aneurysmal malformation (VGAM) is a rare anomaly associated with poor outcomes from high output cardiac failure and neurologic complications. Studies addressing fetal cardiovascular status and outcomes in this population are limited. A single-center retrospective review was conducted on patients with a prenatal diagnosis of VGAM who underwent a fetal echocardiogram between January 2015 and July 2019. Fetal echocardiographic data, brain magnetic resonance imaging (MRI) findings and outcomes were collected. Nine fetuses [median gestational age at echocardiogram 34 (1.1) weeks] were included. All patients had superior vena cava dilation and reversal of diastolic flow in the transverse aortic arch. Median cardiothoracic (CT) ratio was 0.39 (0.09). Right ventricular (RV) and left ventricular (LV) dysfunction was present in 66% and 11% fetuses, respectively. Four out of five patients that underwent postnatal endovascular neurosurgical interventions at our center were alive at follow-up (mean 2.7 years). Of the non-survivors (n = 5), 3 received comfort care because of severe brain damage and died in the neonatal period. Non-survivors more commonly had > mild tricuspid regurgitation (TR) (40% vs. 25%) and > mild RV dilation (60% vs. 25%). Combined cardiac index (CCI) was higher in non-survivors when compared to survivors (672.7 vs. 530.2 ml/kg/min, p = 0.016). Fetuses with significant parenchymal damage on brain MRI tended to have a higher CCI than those without (979.8 vs. 605.0 ml/kg/min, p = 0.047). RV dysfunction, TR and elevated CCI are more commonly seen in non-survivors with VGAM. A higher CCI is seen in those deemed untreatable due to significant parenchymal volume loss. Future multicenter studies are needed to assess for prenatal prediction of outcomes in this high-risk population.

Endovascular Treatment of Malignant Superior Vena Cava Syndrome through Upper-Limb Access: A Comparison between Venous-Dedicated and Conventional Stents.

PURPOSE: To retrospectively evaluate the technical and clinical outcomes of superior vena cava (SVC) stent placement through upper-limb venous access in malignant SVC syndrome (SVCS) and compare the efficacy of different nitinol stent types. MATERIALS AND METHODS: Between 2006 and 2018, 156 patients (132 male; mean age, 62 y; age range, 33-81 y) underwent SVC stent placement for malignant obstructions through upper-limb venous access with 1 of 3 types of nitinol stent: 1 venous-dedicated (Sinus-XL stent) and 2 non-venous-dedicated (E-Luminexx Vascular Stent and Protégé GPS). Cases of common femoral vein access or non-nitinol stents were excluded from further analysis. The mean duration of follow-up was 8 mo. RESULTS: Technical success was achieved in 99.3% of cases. One patient died during the procedure as a result of cardiac tamponade. Balloon predilation was performed in 10 patients and postdilation in 126. Mean procedural time was 34.4 min (range, 18-80 min). Overall survival rates were 92.3%, 57.3%, and 26.8%, and overall primary patency rates were 94.5%, 84.8% and 79.6%, at 1, 6, and 12 mo, respectively. There were no statistically significant differences in primary patency rates between venous- and non-venous-dedicated stents or among different Stanford SVCS grading groups (P > .05). CONCLUSIONS: SVC stent placement through an upper-limb approach is a safe, fast, and effective technique. There is no evident benefit of venous-dedicated vs non-venous-dedicated stents in the treatment of malignant SVCS.

Low preoperative superior vena cava blood flow predicts bidirectional cavopulmonary shunt failure.

BACKGROUND: In this study we sought to determine whether preoperative superior vena cava (SVC) blood flow measured using cardiac magnetic resonance (CMR) predicts physiology and clinical outcome after bidirectional cavopulmonary shunt (BCPS). METHODS: The retrospective single-center study included 65 (2012-2017) patients who underwent BCPS. Preoperative CMR imaging, echocardiography, catheterization, and clinical outcomes were reviewed. SVC flow was measured using phase contrast CMR. The Kaplan-Meier method and Cox regression was used for BCPS takedown-free survival and predictor analyses. RESULTS: The absolute and indexed SVC flow was 0.5 (interquartile range [IQR], 0.4-0.7) L/min and 1.7 (IQR, 1.4-2.0) L/min/mm2 respectively, which was comparable with the SVC blood flow volume previously measured. The median age and body weight at BCPS was 6.5 (IQR, 5.5-8.5) months and 6.9 (IQR, 6.0-7.7) kg. After follow-up, at a median of 17.1 (IQR, 7.9-41.3) months, 14 patients (21.5%) underwent the Fontan completion and 40 (61.5%) with BCPS physiology were waiting for the Fontan completion. The 11 remaining patients (16.9%), included those who underwent takedown (n = 7; 10.8%) or died with a BCPS (n = 4; 6.2%). Severe hypoxia was the leading cause of mortality, directly accounting for two-thirds of deaths (66.6%; 6/9). The BCPS takedown-free survival was 96.8% at 6 months, and 79.9% at 3 years. Preoperative SVC blood flow was significantly positively correlated with early post-BCPS arterial saturation (P = .00). The multivariable analysis showed SVC flow was the only factor associated with BCPS failure (hazard ratio, 0.186; P = .04) among the predictors related to the pre-BCPS anatomy and physiology. CONCLUSIONS: SVC blood flow might be as critically important as pulmonary artery anatomic and physiologic parameters in the evaluation of BCPS candidacy in the single-ventricle population.

Efficacy of endovascular Z-configuration stenting for malignant versus nonmalignant caval obstruction.

OBJECTIVE: The objective of this study was to assess factors associated with symptom resolution after endovascular stenting for superior or inferior vena cava syndrome. METHODS: Eighty-six consecutive vena cava Z-configuration stent placements in 82 patients (53 ± 14 years old) at a single institution were reviewed for patient demographics, comorbidities, and durability of stent patency (also evaluated were persistent or recurrent symptoms, stent occlusion, and need for repeated stenting). Logistic regression was used to identify independent factors associated with stent patency, and Φ coefficients and analysis of variance were used to compare cases subdivided by lesion location (superior vena cava, inferior vena cava) and the presence or absence of malignant disease. RESULTS: Clinical follow-up was available in 77 of 86 (90%) cases. Technical success with clinical failure (persistent symptoms) occurred in 40% of these cases with a median follow-up of 67 (interquartile range, 14-570) days and mortality rate of 63% during this period. Malignant obstructions had a significantly higher clinical failure rate of 54% compared with 15% for nonmalignant obstructions (Φ = 0.34; P = .002). However, only metastatic disease was independently associated with clinical failure when controlling for demographics, other comorbidities, and differential follow-up (adjusted odds ratio, 8.27; 95% confidence interval, 2.79-24.50). CONCLUSIONS: Vena cava Z-stenting effectively resolves symptoms in 85% of nonmalignant obstructions compared with only 46% of malignant obstructions. Patients should be counseled accordingly, and those with malignant obstructions may require closer follow-up to evaluate the need for reintervention and goals of care.

Electrical isolation of the superior vena cava using second-generation cryoballoon in patients with atrial fibrillation.

BACKGROUND: The safety and efficacy of superior vena cava (SVC) isolation using second-generation cryoballoon (CB) ablation remain unknown. METHODS: A total of 26 (3.2%) patients with SVC-related paroxysmal atrial fibrillation (AF) from a consecutive series of 806 patients who underwent second-generation CB were included. Pulmonary vein isolation was initially achieved by CB ablation. If the SVC trigger was determined, the electrical isolation of SVC isolation was performed using the second-generation CB. RESULTS: Real-time SVC potential was observed in all patients. Isolation of the SVC was successfully accomplished in 21 (80.8%) patients. The mean number of freeze cycles in each patient was 2.1 ± 1.1. The mean time to isolation and ablation duration were 22.5 ± 14.2 seconds and 94.5 ± 22.3 seconds, respectively. A transient phrenic nerve (PN) injury was observed in five patients (19.2%). There were two patients (7.7%) experienced reversible sinus node injury during the first application. During a mean follow-up period of 13.2 ± 5.8 months, four patients (15.4%) had atrial arrhythmia recurrences. CONCLUSION: Isolation of SVC using the second-generation 28-mm CB is feasible when SVC driver during AF is identified. Vigilant monitoring of PN function during CB ablation of SVC is needed to avoid PN injury.

Complications of retained cardiac defibrillator coil left in situ.

A 42-year-old man presented to a regional hospital emergency department with a 4-day history of haemoptysis, shortness of breath, pleuritic chest pain, productive cough and subjective fevers. This episode was the third similar presentation in a 2-month period. The patient was known to have dilated cardiomyopathy secondary to amphetamine use and had previously required insertion of automated implantable cardiac defibrillator (AICD). Due to recurrent complications, the AICD had been replaced on two occasions and a superior vena cava (SVC) lead left in situ on its final removal. Clinical examination and investigations revealed lower respiratory tract infection and transthoracic echocardiogram revealed severe left ventricular failure with an ejection fraction of 16%. The patient was admitted under the general medical team for treatment and investigation of suspected bacteraemia and septicaemia secondary to colonisation of the retained AICD lead. He spent 6 days as an in-patient and was discharged on home where he was to be followed up by the advanced heart failure team in a tertiary centre for consideration of new AICD insertion and to explore possibility of retained coil removal. This case report discusses the concerns surrounding retained SVC leads and potential clinical sequalae. As this patient presented three times within a period of 2 months, it was suspected retained SVC lead was a predisposing factor for recurrent lower respiratory infection.

The mechanisms of recurrent atrial arrhythmias after second-generation cryoballoon ablation.

BACKGROUND: In patients with paroxysmal atrial fibrillation (PAF), 10%-15% of patients require repeat procedures after second-generation cryoballoon pulmonary vein isolation (CB-PVI). We sought to explore the mechanisms of recurrences after cryoballoon ablation. METHODS: The data of 122 PAF patients who underwent second procedures for recurrent arrhythmias 7.0 (4.0-12.0) months after the CB-PVI were analyzed. During second procedures, non-PV AF foci were explored with isoproterenol, adenosine, and repetitive cardioversions. RESULTS: In total, 378/487 (77.6%) PVs remained isolated, and reconnections were not observed in any PVs in 59 (48.4%) patients. PV reconnections were associated with recurrences in 38 (31.1%) patients, of whom 33 (86.8%) had reconnections of at least 1 upper PV. In 6 (4.9%) patients, non-PV AF foci were identified in the upper PV antra where cryoballoons cannot isolate but within the circumferential radiofrequency PVI line. Non-PV AF foci were identified in the superior vena cava, right atrial body, left atrial body, and atrial septum in 28 (23.0%), 18 (14.7%), 4 (3.3%), and 5 (4.1%) patients, respectively. Twelve (9.8%) patients had multiple non-PV AF foci. Four (3.3%), 3 (2.4%), and 8 (6.5%) patients underwent second procedures for atrioventricular nodal reentrant tachycardia, atrial flutter, and atrial tachycardias. During 16.0 (8.0-24.0) months of follow-up, freedom from any atrial arrhythmia at 1 year and 2 years after the second procedure was 79.2% and 60.6%. Nineteen (15.5%) patients had antiarrhythmic drug therapy at the last follow-up. CONCLUSIONS: Our study suggested that improvement in the upper PV PVI durability, eliminating arrhythmogenic superior vena cavae and coexisting atrial arrhythmias, and bonus cryoballoon applications at PV antra might improve the single procedure outcome in cryoballoon ablation.

A review of endovascular stenting for superior vena cava syndrome in fibrosing mediastinitis.

Fibrosing mediastinitis (FM) is a rare disorder of inflammation and fibrosis involving the mediastinum. The formation of fibroinflammatory mass in the mediastinum can lead to obstruction of mediastinal structures and cause severe debilitating and life-threatening symptoms. Superior vena cava syndrome (SVCS) is a dreaded complication of FM with no medical therapy proven to be efficacious. Spiral vein grafting has long been utilized as first-line therapy for SVC syndrome due to FM. Endovascular repair with stents and angioplasty for malignant causes of SVC syndrome is well established. However, there are limited data on their utility in SVC syndrome due to FM. We present two cases of SVC syndrome due to FM treated with endovascular stenting and a detailed review of current literature on its utility in SVCS due to benign causes.

Brachiocephalic vein compression caused by a mediastinal cystic tumor presenting with rapidly progressive upper limb swelling and pain in a patient on hemodialysis with a newly created arteriovenous graft.

A 61-year-old man was hospitalized for creating vascular access for maintenance hemodialysis. Chronic interstitial nephritis was the cause of his end-stage kidney disease. An arteriovenous graft (AVG) was selected because superficial veins in his bilateral upper limbs were not suitable for arteriovenous fistula (AVF). Venography did not show any stenotic lesions in the drainage veins bilaterally. Soon after creation of the AVG, his left arm began to swell. Obstruction of the drainage vessels downstream of the AVG was highly suspected. Magnetic resonance imaging disclosed that the left brachiocephalic vein was compressed at the junction of the superior vena cava by a mediastinal cystic tumor. This tumor was 15 mm in diameter and was tentatively diagnosed as a bronchogenic cyst. While initiating hemodialysis using the AVG, the patient's body weight was decreased by the extracorporeal ultrafiltration method, followed by amelioration of swelling in the left arm. Because the swelling and pain of his left upper limb gradually subsided, we finally decided not to close the AVG and continued hemodialysis using the left AVG. He is currently on maintenance hemodialysis for 3 months with a slightly swollen left upper limb. Central venous obstruction or compression is one of the major causes of ipsilateral limb swelling in patients on hemodialysis. Central venous stenosis caused by previous central catheter insertion is often involved. Our case emphasizes the importance of searching for potential anatomical obstruction of drainage vessels by mediastinal tumors as a potential cause of venous hypertension in hemodialysis patients.

Percutaneous paraspinal access to the azygos vein to create a neo-vena cava.

We present the case of a child with congenital heart disease repaired in infancy with diffuse central venous occlusions resulting in central venous insufficiency, superior vena cava (SVC) syndrome, and intracranial bleeds. He presented to the catheterization laboratory for multiple transcatheter interventions to recanalize central venous channels which were unsuccessful by conventional methods. Therefore, extravascular venous channels were created to decompress his upper body by creation of a neo-SVC and his lower body with a neo-azygos vein to the neo-SVC. The latter procedure required direct percutaneous access from a paraspinal approach in order to obtain continuity with the azygos vein. At latest follow-up the patient is clinically well and asymptomatic.

The value of a superior vena cava collapsibility index measured with a miniaturized transoesophageal monoplane continuous echocardiography probe to predict fluid responsiveness compared to stroke volume variations in open major vascular surgery: a prospective cohort study.

Superior vena cava collapsibility index (SVC-CI) and stroke volume variation (SVV) have been shown to predict fluid responsiveness. SVC-CI has been validated only with conventional transoesophageal echocardiography (TEE) in the SVC long axis, on the basis of SVC diameter variations, but not in the SVC short axis or by SVC area variations. SVV was not previously tested in vascular surgery patients. Forty consecutive adult patients undergoing open major vascular surgical procedures received 266 intraoperative volume loading tests (VLTs), with 500 ml of gelatine over 10 min. The hSVC-CI was measured using a miniaturized transoesophageal echocardiography probe (hTEE). The SVV and cardiac index (CI) were measured using Vigileo-FloTrac technology. VLTs were considered 'positive' (≥ 11% increase in CI) or 'negative' (< 11% increase in CI). We compared SVV and hSVC-CI measurements in the SVC short axis to predict fluid responsiveness. Areas under the receiver operating characteristic curves for hSVC-CI and SVV were not significantly different (P = 0.56), and both showed good predictivity at values of 0.92 (P < 0.001) and 0.89 (P < 0.001), respectively. The cutoff values for hSVC-CI and SVV were 37% (sensitivity 90%, specificity of 83%) and 15% (sensitivity 78%, specificity of 100%), respectively. Our study validated the value of the SVC-CI measured as area variations in the SVC short axis to predict fluid responsiveness in anesthetized patients. An hTEE probe was used to monitor and measure the hSVC-CI but conventional TEE may also offer this new dynamic parameter. In our cohort of significant preoperative hypovolemic patients undergoing major open vascular surgery, hSVC-CI and SVV cutoff values of 37% and 15%, respectively, predicted fluid responsiveness with good accuracy.

Influence of Offset on Hemodynamics of Intra-atrial Conduit Fontan's Procedure and Its Clinical Implications.

BACKGROUND: The desirable distance, defined as offset, between the central line of the superior vena cava (SVC) and the intra-atrial conduit after an intra-atrial conduit (IAC) Fontan's procedure remained unclear. We compared the hemodynamic features using virtual surgery with different offset designs in our study. METHODS: Three-dimensional models of IAC Fontan's procedure were reconstructed according to the magnetic resonance imagings (MRIs) of three patients, then four models for each patient with different offsets equaling 100, 67, 33, and 0% of the diameter of the IVC were reconstructed. Computational fluid dynamics (CFD) were performed in each model to predict the best hemodynamic features, including streamlines of blood flow, wall shear stress (WSS), energy loss (EL), and the hepatic flow distribution (HFD) ratio. RESULTS: Comprehensive evaluation of WSS, EL, and HFD revealed than an offset of 33% presents the best hemodynamic performance among the three patients modeled. In patient A, an offset of 33% resulted in the best HFD (left pulmonary artery/right pulmonary artery [LPA/RPA] = 35/65%). In patient B, the best trade-off between HFD (35/65%), and WSS was achieved with an offset of 33%. In patient C, EL peaked at an offset of 0% and significantly dropped at an offset of 33% with a desirable HFD (60/40%). CONCLUSIONS: We verified that the offset distance influences hemodynamic performance in IAC Fontan's procedure. Considering several hemodynamic parameters, the best trade-offs between hemorheology, pulmonary perfusion, and energy efficiency were achieved at an offset of 33%. This distance should be taken into consideration and optimized during the surgical planning for the IAC Fontan's procedure.

Outcomes of Double-patch and Warden Techniques in Patients With Supracardiac Partial Anomalous Pulmonary Venous Connection.

AIM: This study compared outcomes following the double-patch and Warden procedures for correcting partial anomalous connection of the right pulmonary veins to the superior vena cava. METHODS: Eighty (80) patients, aged <18years old, and with partial anomalous connection of the right pulmonary veins to the superior vena cava were randomly assigned into double-patch method (n=40) and Warden procedure (n=40) groups. The median follow-up was 22.5 (range, 12-39) months. The primary endpoint was sinus node dysfunction at the mid-term follow-up period. RESULTS: No early or late mortality occurred. In the early postoperative period, sinus node dysfunction was observed in 27.5% and 5% of cases after double-patch correction and the Warden procedure, respectively (risk ratio, 5.50; 95% confidence interval, 1.30-23.25; p=0.01). At follow-up, sinus node dysfunction persisted in two (5%) patients after double-patch correction. All patients had normal sinus rhythm after the Warden procedure. No early or late pacemaker implantation occurred in either group. No patients had significant pulmonary veins or superior vena cava stenosis. CONCLUSIONS: The double-patch technique and Warden procedure both showed excellent early and mid-term results with no mortality and minimal morbidity. The Warden procedure was associated with less sinus node dysfunction in the early postoperative period than the double-patch technique. There was no significant between-group difference in sinus node dysfunction at the mid-term follow-up.

Bilateral absence of the superior vena cava. Case report and literature review.

Bilateral absence of the superior vena cava (SVC) is an uncommon congenital vascular anomaly, mainly asymptomatic, usually undetected, and often associated with other cardiac anomalies. Though usually harmless and totally innocent, this vascular anomaly might complicate cardiovascular surgery, the insertion of a central venous catheter and the transvenous placement of a pacemaker. This SVC anomaly is still not well known, underdiagnosed and its incidence is much higher than described. A better understanding of this anomaly and its detection could play a key role in avoiding its potential complications. We are sharing a case of a female adult, with no medical history, who presented herself to the department of visceral surgery with a collateral venous circulation of the upper thorax, that was at first, mistaken for a portal hypertension syndrome, findings were pushed to finally conclude a bilateral absence of the SVC.

Perioperative Assessment of Cerebral Oxygen Metabolism in Infants With Functionally Univentricular Hearts Undergoing the Bidirectional Cavopulmonary Connection.

OBJECTIVES: The transition from single-ventricle lesions with surgically placed systemic-to-pulmonary artery shunt to the circulation following a bidirectional cavopulmonary connection results in higher pressure in the superior vena cava when compared with the preceding circulation. The aim of this study was to evaluate the impact of this transition on the perioperative cerebral oxygen metabolism. DESIGN: Prospective observational cohort study. SETTING: Pediatric critical care unit of a tertiary referral center. PATIENTS: Sixteen infants after bidirectional cavopulmonary connection. INTERVENTION: Cardiac surgery (bidirectional cavopulmonary connection). MEASUREMENTS AND MAIN RESULTS: We measured regional cerebral oxygen saturation, amount of hemoglobin, blood flow velocity, and microperfusion immediately before, 12-24 hours, and 36-48 hours following bidirectional cavopulmonary connection. Based on these measurements, we calculated cerebral fractional tissue oxygen extraction and approximated cerebral metabolic rate of oxygen. Mean pressure in the superior vena cava increased significantly (8 vs 17 mm Hg; p < 0.001) following bidirectional cavopulmonary connection. Mean cerebral oxygen saturation increased from 49.0% (27.4-61.0) to 56.9% (39.5-64.0) (p = 0.008), whereas mean cerebral blood flow velocity decreased from 80.0 arbitrary units (61.9-93.0) to 67.3 arbitrary units (59.0-83.3) (p < 0.001). No change was found in the cerebral amount of hemoglobin and in the cerebral microperfusion. Mean cerebral fractional tissue oxygen extraction (0.48 [0.17-0.63] vs 0.30 [0.19-0.56]; p = 0.006) and approximated cerebral metabolic rate of oxygen (5.82 arbitrary units [2.70-8.78] vs 2.27 arbitrary units [1.19-7.35]; p < 0.001) decreased significantly. CONCLUSIONS: Establishment of bidirectional cavopulmonary connection is associated with postoperative improvement in cerebral oxygen metabolism. Cerebral amount of hemoglobin did not increase, although creation of the bidirectional cavopulmonary connection results in significant elevation in superior vena cava pressure. Improvement in cerebral oxygen metabolism was due to lower cerebral blood flow velocity and stable microperfusion, which may indicate intact cerebral autoregulation.