Identification of Factors Influencing Cumulative Long-Term Radiation Exposure in Patients Undergoing EVAR.

Patients who undergo endovascular repair of aortic aneurysms (EVAR) require life-long surveillance because complications including, in particular, endoleaks, aneurysm rupture, and graft dislocation are diagnosed in a certain share of the patient population and may occur at any time after the original procedure. Radiation exposure in patients undergoing EVAR and post-EVAR surveillance has been investigated by previous authors. Arriving at realistic exposure data is essential because radiation doses resulting from CT were shown to be not irrelevant. Efforts directed at identification of factors impacting the level of radiation exposure in both the course of the EVAR procedure and post-EVAR endovascular interventions and CTAs are warranted as potentially modifiable factors may offer opportunities to reduce the radiation. In the light of the risks found to be associated with radiation exposure and considering the findings above, those involved in EVAR and post-EVAR surveillance should aim at optimal dose management.

Allograft Heart Valves: Current Aspects and Future Applications.

Human heart valve allografts continue to represent almost perfect substitutes for heart valves. They have optimal hemodynamic characteristics and are highly resistant to infections. The first clinical use of allograft heart valves was as homovitals being transplanted after antibiotic incubation without any preservation. Since 1968, relatively standardized frozen cryopreservation (SFC) has been employed, including storage in vapor-phase liquid nitrogen. Disadvantages, particularly in pediatric patients, are limited availability due to organ scarcity, inability to grow, degeneration, immune response, and long-term failure. However, in contrast to alternative prosthetic or bioprosthetic heart valve replacements, they represent the best pediatric and juvenile replacement options for the pulmonary valve. Application of multiphoton imaging analysis for three-dimensional visualization of elastin and collagen by induction of autofluorescence without chemical fixation, embedding, and staining has revealed partial destruction of elastic and collagenous matrix in SFC valves. As the overall amount of collagen and elastin remains unchanged, the observed destruction is attributed to freezing-induced extracellular matrix damages due to ice crystal formation during SFC. The objective of this review is an assessment of current allograft preservation methods and the potential of novel preservation techniques to avoid ice formation with accompanied better long-term function.

Kinetics of circulating endothelial progenitor cells in patients undergoing carotid artery surgery.

AIM: Endothelial progenitor cells (EPCs) are primitive cells found in the bone marrow and peripheral blood (PB). In particular, the potential of EPCs to differentiate into mature endothelial cells remains of high interest for clinical applications such as bio-functionalized patches for autologous seeding after implantation. The objective of this study was to determine EPCs' kinetics in patients undergoing carotid artery thromboendarterectomy (CTEA) and patch angioplasty. METHODS: Twenty CTEA patients were included (15 male, mean age 76 years). PB samples were taken at 1 day preoperatively, and at 1, 3, and 5 days postoperatively. Flow cytometric analysis was performed for CD34, CD133, KDR, and CD45. Expression of KDR, SDF-1α, and G-CSF was analyzed by means of enzyme-linked immunosorbent assay. RESULTS: Fluorescence-activated cell sorting analysis revealed 0.031%±0.016% (% of PB mononuclear cells) KDR+ cells and 0.052%±0.022% CD45-/CD34+/CD133+ cells, preoperatively. A 33% decrease of CD45-/CD34+/CD133+ cells was observed at day 1 after surgery. However, a relative number (compared to initial preoperative values) of CD45-/CD34+/CD133+ cells was found on day 3 (82%) and on day 5 (94%) postoperatively. More profound upregulated levels of CD45-CD34+/CD133+ cells were observed for diabetic (+47% compared to nondiabetic) and male (+38% compared to female) patients. No significant postoperative time-dependent differences were found in numbers of KDR+ cells and the concentrations of the cytokines KDR and G-CSF. However, the SDF-1α levels decreased significantly on day 1 postoperatively but returned to preoperative levels by day 3. CONCLUSION: CTEA results in short-term downregulation of circulating EPCs and SDF-1α levels. Rapid return to baseline levels might indicate participation of EPCs in repair mechanisms following vascular injury.

Fibrin sealant patch for repair of acute type a aortic dissection.

INTRODUCTION: The use of glues to repair disrupted tissue during acute type-A aortic dissection (TAD) surgery may be discontinuous, and cause embolization and cell necrosis. We report a method of fibrin sealant patch (FSP) to reinforce dissected aortic tissue with a collagen double layer coated with fibrinogen/thrombin on either side (TachoSil®; Takeda, Konstanz, Germany). METHODS: In 12 patients (seven male, 66.9 ± 11.7 years) with acute TAD we performed FSP of the intima-media disruption at the proximal and distal anastomosis of the aorta. We analyzed the perioperative course and echocardiographical, radiological, and clinical outcomes up to one year. Additionally, we investigated the adhesive potential of the FSP in vitro. RESULTS: In vitro, the adhesive strength of the FSP was 60 N/cm(2). In-hospital mortality was 8.3% (n = 1), recovery was satisfactory with no major neurologic events, mean ICU stay was 13.6 ± 6.0 days, mean hospital stay was 20.7 ± 4.4 days. A total of 7.0 ± 2.6 RBC, 3.4 ± 1.5 platelets, and 8.0 ± 4.3 FFP were transfused. One-year survival was 83.3%. In 6/6 DeBakey II dissections the intimal tear was completely resected, in 2/6 DeBakey I dissections the false lumen in the descending aorta completely collapsed. No redissections and no relevant aortic valve insufficiencies were seen during follow-up. CONCLUSION: This analysis shows that FSP using a collagen matrix double layer coated with fibrinogen/thrombin is feasible, safe, and effective in repairing the dissected aortic tissue. It results in continuous reinforcement of aortic tissue and completely avoids the need for conventional glues.

Bridge to recovery or permanent system implantation: an eight-year single-center experience in transvenous semipermanent pacing.

BACKGROUND: To compare the risks, implications, and outcomes of transvenous semipermanent pacing as a bridge to permanent system implantation or recovery. METHODS: We investigated semipermanent transvenous pacing systems consisting of one (n = 57%) or two (n = 3%) bipolar active-fixation pacing leads and an attached epicutaneous pulse generator implanted from 2000 to 2009. The study population comprised 60 patients aged 72.9 ± 10.5 years (44 [73.3%] male). Forty-two (70%) were enrolled for complete system explantation for cardiac-implanted electronic devices associated infection. Eighteen (30%) required temporary pacing in the context of a variety of mostly severe cardiac and noncardiac conditions. The semipermanent pacing systems were removed after implantation of permanent systems or recovery of a noncompromising heart rhythm, respectively. RESULTS: Transvenous semipermanent lead implantation was successful in 59 (98.3%) patients. Major and minor intraoperative complications occurred in one case (1.7%) each. The semipermanent systems were left in situ for a mean period of 14.6 ± 8.1 days). They served as a bridge to permanent system implantation in 68.3% (n = 41) and as a bridge to recovery of a noncompromising heart rhythm in 11.7% (n = 7). Four patients (8.3%) died with the semipermanent pacing system in situ, and seven (11.7%) were transferred to external hospitals with semipermanent pacing systems. CONCLUSIONS: Transvenous semipermanent pacing with bipolar active-fixation leads and epicutaneous pulse generators provide an important option for prolonged temporary pacing as a bridge to permanent system implantation or recovery.

Application of intravascular dissection devices for closed chest coronary sinus lead extraction: an interdisciplinary approach.

BACKGROUND: Increasing application of cardiac resynchronization therapy is accompanied by an increase in patients requiring removal of coronary sinus (CS) leads. The aim of this study was to determine outcomes of closed chest CS lead extraction using intravascular dissection devices. METHODS: Between 2000 and 2011, 41 patients (80.5% men; aged 64.2±13.8 years) underwent transvenous CS lead extraction procedures. Reasons for lead extraction were infection in 9, CS lead dislodgement in 15, lead malfunction, including manufacturer-initiated product recall in 6, phrenic nerve stimulation in 5, combinations of causes in 5, and elective extraction concomitant with generator replacement for battery depletion in 1. RESULTS: In addition to 24 isolated CS lead extractions, we performed 17 multiple lead extractions (2 to 4 leads) after a mean of 30.6±32.5 months. The time elapsed from implantation was 4.6±9.1 months for isolated CS and 42.6±32.4 months for multiple lead extractions. Extraction by direct manual traction was feasible in 13 patients by locking stylets in 6. Escalation to mechanical sheaths was required in 17 patients and to electrosurgical sheaths in 5. More aggressive methods were associated with longer implantation times and positive infection status. No deaths or major periprocedural complications occurred. Six minor postprocedural complications, of which three were surgically related, occurred in 5 patients. CONCLUSIONS: Closed chest CS lead extraction can be safely performed with excellent results. We recommend an escalating approach from isolated manual traction over locking stylets to mechanical sheaths and, eventually, electrosurgical dissection devices. The application in mainly high-risk patients demands an interdisciplinary approach to enhance safety and limit morbidity and death.

Ice-free cryopreservation of heart valve allografts: better extracellular matrix preservation in vivo and preclinical results.

The purpose of this study was evaluation of an ice-free cryopreservation method for heart valves in an allogeneic juvenile pulmonary sheep implant model and comparison with traditionally frozen cryopreserved valves. Hearts of 15 crossbred Whiteface sheep were procured in Minnesota. The valves were processed in South Carolina and the pulmonary valves implanted orthotopically in 12 black faced Heidschnucke sheep in Germany. The ice-free cryopreserved valves were cryopreserved in 12.6 mol/l cryoprotectant (4.65, 4.65, and 3.31 mol/l of dimethylsulfoxide, formamide and 1,2-propanediol) and stored at -80°C. Frozen valves were cryopreserved by controlled slow rate freezing in 1.4 mol/l dimethylsulfoxide and stored in vapor-phase nitrogen. Aortic valve tissues were used to evaluate the impact of preservation without implantation. Multiphoton microscopy revealed reduced but not significantly damaged extracellular matrix before implantation in frozen valves compared with ice-free tissues. Viability assessment revealed significantly less metabolic activity in the ice-free valve leaflets and artery samples compared with frozen tissues (P < 0.05). After 3 and 6 months in vivo valve function was determined by two-dimensional echo-Doppler and at 7 months the valves were explanted. Severe valvular stenosis with right heart failure was observed in recipients of frozen valves, the echo data revealed increased velocity and pressure gradients compared to ice-free valve recipients (P = 0.0403, P = 0.0591). Histo-pathology showed significantly thickened leaflets in the frozen valves (P < 0.05) and infiltrating CD3+ T-cells (P < 0.05) compared with ice-free valve leaflets. Multiphoton microscopy at explant revealed reduced inducible autofluorescence and extracellular matrix damage in the frozen explants and well preserved structures in the ice-free explant leaflets. In conclusion, ice-free cryopreservation of heart valve transplants at -80°C avoids ice formation, tissue-glass cracking and preserves extracellular matrix integrity resulting in minimal inflammation and improved hemodynamics in allogeneic juvenile sheep.

Development of a simplified ice-free cryopreservation method for heart valves employing VS83, an 83% cryoprotectant formulation.

We have previously demonstrated storage of ice-free cryopreserved heart valves at -80°C without the need for liquid nitrogen, with the aims of decreasing manufacturing costs and reducing employee safety hazards. The objectives of the present study were a further simplification of the ice-free cryopreservation method and characterization of tissue viability. Porcine pulmonary heart valves were permeated with an 83% cryoprotectant solution (VS83) followed by rapid cooling and storage at -80°C. The cryoprotectants were added and removed in either single or multiple steps. Fresh untreated frozen controls employing 10% dimethylsulfoxide and controlled rate freezing to -80°C, and storage in vapor phase nitrogen were also performed. After rewarming and washing, cryopreserved leaflets were compared with fresh controls using the resazurin reduction metabolism assay. Comparison of valve tissues in which the cryoprotectants were added and removed in either single or multiple steps demonstrated similar viability results for the muscle, conduit, and leaflet components. The ice-free cryopreserved conduit and leaflet components were significantly less viable than either fresh or frozen tissues. The muscle component, although less viable, was not significantly different. The changes in tissue viability were a function of cryoprotectant exposure, and resulting cytotoxicity, not temperature reduction during storage. TUNEL staining showed that ice-free cryopreservation did not induce significant amounts of apoptosis, suggesting that necrosis is the predominant cell death pathway in ice-free cryopreserved heart valves. There was very little difference in cell viability when the cryoprotectants were added and removed in a single step versus multiple steps. Ice-free cryopreserved valve tissues demonstrated very low viability compared with controls. These results support further simplification of the ice-free cryopreservation method.

The performance of ice-free cryopreserved heart valve allografts in an orthotopic pulmonary sheep model.

Transplantation of cryopreserved heart valves (allografts) is limited by immune responses, inflammation, subsequent structural deterioration and an expensive infrastructure. In previous studies we demonstrated that conventional frozen cryopreservation (FC) is accompanied by serious alterations of extracellular matrix (ECM) structures. As the main culprit of the observed damages ice crystal formation was identified. Objective of this study was the application principles of cryoprotection as observed in nature, occurring in animals or plants, for ice-free cryopreservation (IFC) of heart valves. Using IFC, valves were processed and stored above the glass transition temperature of the cryoprotectant formulation (-124 degrees C) at -80 degrees C to avoid any ice formation, tissue-glass cracking and preserving ECM. After implantation in the orthotopic pulmonary position in sheep, we demonstrate that IFC resulted in cell free matrices, while maintaining crucial ECM-components such as elastin and collagen, translating into superior hemodynamics. In contrast, we reveal that FC valves showed ECM damage that was not restored in vivo, and T-cell inflammation of the stroma with significant leaflet thickening. Compared to currently applied FC practice IFC also reduced infrastructural needs for preservation, storage and shipping. These results have important implications for clinical valve transplantation including the promise of better long-term function and lower costs.

Transvenous removal of an entangled central venous line following complex cardiac surgery.

Unintended internal suturing of central venous lines or pulmonary artery catheters in the superior caval vein or the right atrium following cardiac surgery remains a rare but troublesome complication. The line is normally entangled in safety or hemostasis sutures after the removal of the superior caval cannulation. If mild tension is unsuccessful, the patient normally undergoes resternotomy. The objective of this brief communication is to describe of a simple and safe removal method using a transvenous rotational cutting device to divide the hemostasis suture. In order to avoid complicating bleeding, a time delay between initial placement and removal is highly recommended. For extraction, a fully equipped cardiovascular operating room with central venous and arterial lines, attached defibrillator pads, transesophageal echo monitoring, fluoroscopy, and a surgical team, including a heart and lung machine and a perfusionist standby, is mandatory.

Changes in sialic acid expression in the lung during intrauterine development of the human fetus.

Sialic acid is a component of glycoproteins that influences enzymatic and receptor functions of cells. During proliferation and differentiation of tissues, sialic acid can serve as a recognition determinant in intercellular communication and interactions of cells with the extracellular matrix. In the present study, sialic acid expression in relation to developmental maturity of the lung has been studied. We analyzed 12 necroptic lung specimens from foetuses of different gestational ages from the 15th week to the neonate. Sections were stained histochemically using 3 lectins specific for sialic acid: Tritrichomonas mobilensis lectin (TML), specific for sialic acid without linkage preference, Sambucus nigra agglutinin (SNA), specific for alpha2,6-linked sialic acid, and Maackia amurensis leucoagglutinin (MAL), specific for alpha2,3-linked sialic acid. MAL positivity dominated over SNA positivity showing prevalence of alpha2,3-linked sialic acids to be homogeneously distributed in the lung at the canalicular stage of development. In more mature lungs, well-differentiated bronchial epithelium showed strong sialic acid expression of both linkages. Sialic acid with alpha2,6 linkage dominated in vascular endothelium. Our results showed a slight decrease in sialic acid expression in lungs with gestational age to a relative minimum before birth. Lectin staining of mature lung tissue showed intense sialic acid expression in alveolar epithelial type II cells. Changes in expression of specific sialic acids during differentiation of the lungs may be useful as marker of the degree of maturity of the foetus.