Preserving Endothelial Integrity in Human Saphenous Veins during Preparation for Coronary Bypass Surgery.

INTRODUCTION: While multiple factors influence coronary artery bypass graft (CABG) success rates, preserving saphenous vein endothelium during surgery may improve patency. Standard preparations include saphenous vein preparation in heparinized saline (saline) which can result in endothelial loss and damage. Here, we investigated the impact of preparing saphenous graft vessels in heparinized patient blood (blood) versus saline. METHODS: Saphenous vein tissues from a total of 23 patients undergoing CABG were split into 2 groups (1) saline and (2) heparinized patient blood. Excess tissue was fixed for analysis immediately following surgery. Level of endothelial coverage, oxidative stress marker 4-hydroxynonenal (4HNE), and oxidative stress protective marker nuclear factor erythroid 2-related factor 2 (NRF2) were evaluated. RESULTS: In saline patient veins, histological analysis revealed a limited luminal layer, suggesting a loss of endothelial cells (ECs). Immunofluorescent staining of EC markers vascular endothelial cadherin (VE-cadherin) and endothelial nitric oxide identified a significant improvement in EC coverage in the blood versus saline groups. Although both treatment groups expressed 4HNE to similar levels, EC blood samples expressed higher levels of NRF2. CONCLUSION: Our data indicate that use of heparinized patient blood helps preserve the endothelium and promotes vein graft health. This has the potential to improve long-term outcomes in patients.

A retrospective comparison of albumin versus mannitol priming fluid with relation to postoperative atrial fibrillation.

BACKGROUND AND AIM OF THE STUDY: Postoperative atrial fibrillation (POAF) is a common complication following cardiac surgery which can result in increased mortality and increased healthcare costs. During Hurricane Maria (2017), a nationwide shortage of mannitol occurred, and our institution switched to the utilization of albumin as a priming fluid solution. We observed decreased rates of POAF during that time and began alternating albumin and mannitol priming fluid solutions. We hypothesized this observation may be from altered perinexal conduction from albumin utilization. METHODS: A retrospective chart review of all patients from January 2020 through December 2020 who underwent cardiac surgery was performed, to determine if albumin was associated with reduced POAF rates. Two hundred and thirteen patients were identified and 4 were excluded. Two hundred and nine patients (110 albumin priming fluid and 99 mannitol priming fluid) were included in our final analysis. RESULTS: Analysis was performed for all patients with POAF and in patients with new-onset AF (without a history of prior AF) after surgery. POAF rates showed no statistically significant difference between cohorts. For all patients, POAF occurred in 43% of the albumin subgroup and 47% of the mannitol subgroup (p = .53) and for patients with new-onset AF, POAF occurred in 35% of the albumin subgroup versus 42% of the mannitol subgroup (p = .36). Logistic regression revealed that age, ejection fraction and cardiopulmonary bypass time was associated with POAF, in our cohort. CONCLUSIONS: The use of albumin compared to mannitol as priming fluid solutions was not associated with statistically significant reductions in POAF rate, in our population.

Intercalated Disk Extracellular Nanodomain Expansion in Patients With Atrial Fibrillation.

Aims: Atrial fibrillation (AF) is the most common sustained arrhythmia. Previous evidence in animal models suggests that the gap junction (GJ) adjacent nanodomain - perinexus - is a site capable of independent intercellular communication via ephaptic transmission. Perinexal expansion is associated with slowed conduction and increased ventricular arrhythmias in animal models, but has not been studied in human tissue. The purpose of this study was to characterize the perinexus in humans and determine if perinexal expansion associates with AF. Methods: Atrial appendages from 39 patients (pts) undergoing cardiac surgery were fixed for immunofluorescence and transmission electron microscopy (TEM). Intercalated disk distribution of the cardiac sodium channel Nav1.5, its ß1 subunit, and connexin43 (C×43) was determined by confocal immunofluorescence. Perinexal width (Wp) from TEM was manually segmented by two blinded observers using ImageJ software. Results: Nav1.5, ß1, and C×43 are co-adjacent within intercalated disks of human atria, consistent with perinexal protein distributions in ventricular tissue of other species. TEM revealed that the GJ adjacent intermembrane separation in an individual perinexus does not change at distances greater than 30 nm from the GJ edge. Importantly, Wp is significantly wider in patients with a history of AF than in patients with no history of AF by approximately 3 nm, and Wp correlates with age (R = 0.7, p < 0.05). Conclusion: Human atrial myocytes have voltage-gated sodium channels in a dynamic intercellular cleft adjacent to GJs that is consistent with previous descriptions of the perinexus. Further, perinexal width is greater in patients with AF undergoing cardiac surgery than in those without.

A prospective, randomized controlled trial comparing 3 dressing types following sternotomy.

Dressings are an important aspect of post-sternotomy care. A prospective, randomized, controlled trial was conducted between July 2010 and August 2012 to compare wound and patient outcomes among 3 marketed postoperative dressings. Using convenience sampling methods, 315 patients requiring a sternotomy incision followed by hospitalization were randomly assigned to postoperative care with a dry sterile (n = 106), metallic silver-containing (n = 105), or ionic silver-containing (n = 104) dressing. Application time and ease of dressing application were assessed. The dry dressings remained in place for 24 to 48 hours. On postoperative day 5 or at time of discharge, the silver dressings were removed and wound outcomes (degree of wound approximation, skin integrity, wound exudate, presence/absence of necrotic tissue), presence/absence of surgical site infection, patient comfort, and dressing factors (ease of removal, dressing integrity) were evaluated. All participants received the same preoperative skin preparation and intravenous antibiotics. Data were analyzed using Fisher's exact chi-squares and 1-way ANOVA. No statistically significant differences were found among the dressings in terms of wound healing or infection rate, but statistically significant differences were noted in patient comfort and certain dressing factors. When comparing all 3 dressings, the dry sterile dressing took less time to apply (P = 0.000) and was easiest to apply (P = 0.000). Use of the metallic silver dressing resulted in the least patient-reported pain upon removal (P = 0.015), and incision assessment was easiest with the ionic silver dressing (P = 0.000). When comparing the 2 silver dressings, the metallic silver dressing was easiest to remove (P = 0.003) but had less integrity at the time of removal (P = 0.007). None of the patients in the ionic silver and 1 patient (1%) in the metallic silver dressing group developed a deep infection. Additional research is warranted to determine best practice in postoperative, clean surgical incision management, including sternotomy wounds.