Pascal M. Dohmen

Ross operation with a tissue-engineered heart valve

BACKGROUND The Ross procedure has gained increasing acceptance due to excellent hemodynamic results by replacing the diseased aortic valve with the viable autologous pulmonary valve. Consequently, the right ventricular outflow tract (RVOT) has to be reconstructed. In this report a viable heart valve was created from decellularized cryopreserved pulmonary allograft that was seeded with viable autologous vascular endothelial cells (AVEC). METHODS A 43-year-old patient suffering from aortic valve stenosis underwent a Ross operation on May 20, 2000, using a tissue engineered (TE) pulmonary allograft to reconstruct the RVOT. Four weeks before the operation a piece of forearm vein was harvested to separate, culture, and characterize AVEC. Follow-up was completed at discharge, 3, 6, and 12 months postoperatively by clinical evaluation, transthoracic echocardiography (TTE), and magnetic resonance imaging (MRI). Additionally, at 1-year follow-up a multislice computed tomographic scan was performed. RESULTS After four weeks of culturing 8.34 x 10(6) AVEC were available to seed a 27-mm decellularized pulmonary allograft. Trypan blue staining confirmed 96.0% viability. Reendothelialization rate after seeding was 9.0 x 10(5) cells/cm2. TTE and MRI revealed excellent hemodynamic function of the TE heart valve and the neoaortic valve as well. Multislice computed tomography revealed no evidence of valvular calcification. CONCLUSIONS After 1 year of follow-up the patient is in excellent condition without limitation and exhibits normal aortic and pulmonary valve function.

Ten Years of Clinical Results With a Tissue-Engineered Pulmonary Valve

BACKGROUND This study was performed to collect prospective safety and effectiveness data from a tissue-engineered heart valve implanted for reconstruction of the right ventricular outflow tract during the Ross operation. METHODS From May 2000 until June 2002, 11 consecutive patients, mean age 39.6 ± 10.3 years, received a tissue-engineered heart valve (additive and logistic European System for Cardiac Operative Risk Evaluation, respectively, 3.3 ± 1.3 and 2.8% ± 1.4%). Two to four weeks prior to the Ross operation a piece of forearm vein or saphenous vein was harvested to isolate, characterize, and expand endothelial cells. A cryopreserved pulmonary allograft was decellularized, coated, and seeded with autologous vascular endothelial cells, using a specially developed bioreactor. Cell seeding density was 1.1 × 10(5) ± 0.5 × 10(5) cells/cm(2) with a viability of 93.2% ± 2.1%. RESULTS All patients survived surgery. Postoperatively no fever of unknown origin was evident. Currently all patients are in New York Heart Association class I. Evaluation of the tissue-engineered heart valve by transthoracic echocardiography showed a mean pressure gradient of 5.4 ± 2.0 mm Hg at 10 years. Multislice computed tomography showed no calcification up to 10 years. CONCLUSIONS Tissue-engineered heart valves showed excellent hemodynamic performance and may prevent degeneration during long-term follow-up.

A Randomized Multicenter Trial of Minimally Invasive Rapid Deployment Versus Conventional Full Sternotomy Aortic Valve Replacement

BACKGROUND Minimally invasive surgical procedures (MIS) may offer several advantages over conventional full sternotomy (FS) aortic valve replacement (AVR). A novel class of aortic valve prostheses has been developed for rapid-deployment AVR (RDAVR). We report a randomized, multicenter trial comparing the outcomes for MIS-RDAVR with those of conventional FS-AVR. METHODS A total of 100 patients with aortic stenosis were enrolled in a prospective, multicenter, randomized comparison trial (CADENCE-MIS). Exclusion criteria included ejection fraction below 25%, AVR requiring concomitant procedures, and recent myocardial infarction or stroke. Patients were randomized to undergo MIS-RDAVR through an upper hemisternotomy (n = 51) or AVR by FS with a conventional stented bioprosthesis (n = 49). Three patients were excluded before the procedure, and 3 more patients who were randomized to undergo RDAVR were excluded because of their anatomy. Procedural, early clinical outcomes, and functional outcomes were assessed for the remaining 94 patients. Hemodynamic performance was assessed by an echocardiography core laboratory. RESULTS Implanted valve sizes were similar between groups (22.9 ± 2.1 vs 23.0 ± 2.1 mm, p = 0.9). MIS-RDAVR was associated with significantly reduced aortic cross-clamp times compared with FS-AVR (41.3 ± 20.3 vs 54.0 ± 20.3 minutes, p < 0.001), although cardiopulmonary bypass times were similar (68.8 ± 29.0 vs 74.4 ± 28.4 minutes, p = 0.21). Early clinical outcomes were similar between the two groups, including quality of life measures. The RDAVR patients had a significantly lower mean transvalvular gradient (8.5 vs 10.3 mm Hg, p = 0.044) and a lower prevalence of patient-prosthesis mismatch (0% vs 15.0%, p = 0.013) 3 months postoperatively compared with the FS-AVR patients. CONCLUSIONS RDAVR by the MIS approach is associated with significantly reduced myocardial ischemic time and better valvular hemodynamic function than FS-AVR with a conventional stented bioprosthesis. Rapid deployment valves may facilitate the performance of MIS-AVR.

Antibiotic resistance in common pathogens reinforces the need to minimise surgical site infections

Surgical site infections (SSIs) remain an important cause of postoperative morbidity and mortality and generate considerable additional healthcare and societal costs. Most SSIs are caused by skin-derived bacteria such as Staphylococcus aureus and coagulase-negative staphylococci. Antimicrobial resistance among these and other clinically important pathogens is an increasing problem. Thus, while the overall risk of SSI is influenced by numerous patient- and procedure-specific characteristics, effective antibiotic prophylaxis and skin preparation are important components of the polymodal approach to SSI prevention. Published guidelines recommend that selection of antimicrobial agents for prophylactic use should take into account the expected flora, the ability of the agent to reach the target tissue at appropriate concentrations, bacterial resistance patterns and drug pharmacokinetics. Consistent with proper antimicrobial stewardship, antibiotic prophylaxis should use an appropriate drug and optimise the dose and duration of treatment to minimise toxicity and conditions for selection of resistant bacterial strains. Because the risk of developing SSI depends in part on the extent of wound contamination with virulent bacteria, efficient preoperative patient skin preparation is essential to decrease the number of potential wound contaminants. A recent development to reduce the risk of surgical site contamination by skin flora is a cyanoacrylate-based microbial sealant that is applied before surgery and dries to immobilise skin bacteria under a breathable film. This novel mechanism of action is not compromised by, and does not promote, bacterial resistance and, with minimal potential to cause skin reactions, the microbial sealant is an innovative addition to available options for SSI prophylaxis.

Minimal invasive aortic valve replacement surgery is associated with improved survival: a propensity-matched comparison

OBJECTIVES To compare early and long-term outcomes of minimally invasive surgery (MIS) versus full sternotomy (FS) isolated aortic valve replacement (AVR). METHODS We retrospectively analysed all patients who underwent isolated bioprosthetic AVR between 2003 and March 2012 at our institution. Matching was performed based on a propensity score, which was obtained using the output of a logistic regression on relevant preoperative risk factors. Mean follow-up was 3.1±2.7 years (range 0-9.0 years) and was 99.8% complete. RESULTS A total of 2051 patients (FS, 1572; MIS, 479) underwent isolated bioprosthetic AVR during the study period. MIS patients were significantly younger (67.8±11.2 vs 70.4±9.4 years) and had a lower logistic EuroSCORE (6.6±6.4 vs 11.2±13.4%, both P<0.001). Propensity matching resulted in 477 matched patients from each group, with no significant differences in any of the preoperative variables. Aortic cross-clamp times were significantly longer in MIS patients (59.4±16.0 vs 56.9±14.6 min, P=0.008). Nonetheless, MIS AVR was associated with a significantly lower incidence of intra-aortic balloon pump usage (0.4 vs 2.1%, P=0.042) and in-hospital mortality (0.4 vs 2.3%, P=0.013), while FS patients had a lower rate of re-exploration for bleeding (1.5 vs 4.2%, P=0.019). Five- and 8-year survival post-AVR was significantly higher in MIS patients (89.3±2.4% and 77.7±4.7% vs 81.8±2.2% and 72.8±3.1%, respectively, P=0.034). Cox regression analysis revealed MIS (hazard ratio: 0.47, 95% confidence interval: 0.26-0.87) as an independent predictor of long-term survival. CONCLUSION MIS AVR is associated with very good early and long-term survival, despite longer myocardial ischaemic times. MIS AVR can be performed safely with results that are at least equivalent to those achieved through an FS.

Is There a Possibility for a Glutaraldehyde-Free Porcine Heart Valve to Grow?

Objective: A challenging issue is to create a heart valve with growth and remodeling potential, which would be of great interest for congenital heart valve surgery. This study was performed to evaluate the growth and remodeling potentials of a decellularized heart valve. Methods: In 4 juvenile sheep (age 12 ± 1 weeks) with a weight of 24.3 ± 4.4 kg, a 17-mm diameter decellularized porcine valve was implanted as pulmonary valve replacement. Valve growth was evaluated by transthoracic echocardiography. At explantation, valves were evaluated by gross examination, light microscopy (hematoxylin and eosin, von Kossa, Sirius red, Weigert and Gomori staining), electron microscopy and immunohistochemistry. Atomic absorption spectrometry was performed to evaluate calcium content. Results: All animals showed fast recovery. The mean follow-up was 9.0 ± 1.8 months. All sheep at least doubled their weight (54.3 ± 9.2 kg). Echocardiography showed no regurgitation and a flow velocity of 0.7 ± 0.1 m/s at the latest follow-up. The valve diameter increased from 17.6 ± 0.5 to 27.5 ± 2.1 mm (p < 0.018). Gross examination showed a similar wall thickness of the implanted valve and native pulmonary wall, with smooth and pliable leaflets. Histology showed a monolayer of endothelial cells, fibroblast ingrowth and production of new collagen. No calcification was seen at von Kossa staining, confirmed by low calcium content levels of the valve wall and leaflets at atomic absorption spectrometry. Conclusions: This glutaraldehyde-free heart valve showed not only the absence of calcification, but also remodeling and growth potential.

Splanchnic oxygen transport, hepatic function and gastrointestinal barrier after normothermic cardiopulmonary bypass

Background:  The effect of non‐pulsatile, normothermic cardiopulmonary‐bypass (CPB) on the splanchnic blood‐flow and oxygen‐transport, the hepatic function and the gastrointestinal barrier were observed in a prospective observational study in 31 adults undergoing cardiac valve replacement surgery.

Reduction in surgical site infection in patients treated with microbial sealant prior to coronary artery bypass graft surgery: a case–control study

Surgical site infection (SSI) is a serious complication after cardiac surgery. This case-control study investigated the effect of a cyanoacrylate-based microbial skin sealant (InteguSeal) applied preoperatively on the SSI rate in patients undergoing coronary artery bypass graft (CABG) surgery. Of 676 patients who underwent CABG surgery with or without concomitant procedure(s) between March and November 2007, 545 received standard preoperative care and 131 also received pretreatment with the microbial sealant. Of these, 90 cases pretreated with microbial sealant and 90 controls were matched using established preoperative and intraoperative risk factors for SSI. Preoperative risk scores for SSI were 9.9+/-4.3 and 9.7+/-4.0 (P=0.747) for the microbial sealant and the control group, respectively, and combined preoperative-intraoperative risk scores were 9.7+/-4.1 and 8.7+/-3.5 (P=0.080), respectively. Carotid artery disease (P=0.019), congestive heart failure (P=0.019), acute myocardial infarction (P=0.001) and emergency surgery (P=0.026) were significantly more common in the microbial sealant group. Follow-up was 100% for both groups. Superficial or deep sternal infection 30 days post surgery developed in seven patients (7.8%) in the control group compared with one patient (1.1%) in the microbial sealant group (odds ratio 7.5). In summary, the inclusion of microbial sealant in preoperative patient preparation seems to reduce the incidence of SSI following CABG surgery; further larger studies are needed before firm conclusions can be drawn.

Three-year hemodynamic performance, left ventricular mass regression, and prosthetic-patient mismatch after rapid deployment aortic valve replacement in 287 patients

OBJECTIVE Superior aortic valve hemodynamic performance can accelerate left ventricular mass regression and enhance survival and functional status after surgical aortic valve replacement. This can be achieved by rapid deployment aortic valve replacement using a subannular balloon-expandable stent frame, which functionally widens and reshapes the left ventricular outflow tract, to ensure a larger effective orifice area compared with conventional surgical valves. We report the intermediate-term follow-up data from a large series of patients enrolled in the Surgical Treatment of Aortic Stenosis With a Next Generation Surgical Aortic Valve (TRITON) trial. METHODS In a prospective, multicenter (6 European hospitals), single-arm study, 287 patients with aortic stenosis underwent rapid deployment aortic valve replacement using a stented trileaflet bovine pericardial bioprosthesis. Core laboratory echocardiography was performed at baseline, discharge, and 3 months, 1 year, and 3 years after rapid deployment aortic valve replacement. RESULTS The mean patient age was 75.7 ± 6.7 years (range, 45-93; 49.1% women). The mean aortic valve gradient significantly decreased from discharge to 3 years of follow-up. The mean effective orifice area remained stable from discharge to 3 years. At 1 year, the left ventricular mass index had decreased by 14% (P < .0001) and at 3 years by 16% (P < .0001) compared with at discharge. The prevalence of severe patient-prosthesis mismatch was 3% at discharge and remained stable during the follow-up period. CONCLUSIONS In a large series of elderly patients with symptomatic severe aortic stenosis, rapid deployment aortic valve replacement using a subannular balloon-expandable stent frame demonstrated excellent hemodynamic performance and significant left ventricular mass regression. With continued follow-up, future studies will establish whether these favorable structural changes correlate with improvement in long-term survival and functional status.

The impact of an hematocrit of 20% during normothermic cardiopulmonary bypass for elective low risk coronary artery bypass graft surgery on oxygen delivery and clinical outcome – a randomized controlled study [ISRCTN35655335]

IntroductionCardiopulmonary bypass (CPB) induces hemodilutional anemia, which frequently requires the transfusion of blood products. The objective of this study was to evaluate oxygen delivery and consumption and clinical outcome in low risk patients who were allocated to an hematocrit (Hct) of 20% versus 25% during normothermic CPB for elective coronary artery bypass graft (CABG) surgery.MethodsThis study was a prospective, randomized and controlled trial. Patients were subjected to normothermic CPB (35 to 36°C) and were observed until discharge from the intensive care unit (ICU). Outcome measures were calculated whole body oxygen delivery, oxygen consumption and clinical outcome. A nonparametric multivariate analysis of variance for repeated measurements and small sample sizes was performed.ResultsIn a total of 54 patients (25% Hct, n = 28; 20% Hct, n = 26), calculated oxygen delivery (p = 0.11), oxygen consumption (p = 0.06) and blood lactate (p = 0.60) were not significantly different between groups. Clinical outcomes were not different between groups.ConclusionThese data indicate that an Hct of 20% during normothermic CPB maintained calculated whole body oxygen delivery above a critical level after elective CABG surgery in low risk patients. The question of whether a transfusion trigger in excess of 20% Hct during normothermic CPB is still supported requires a larger prospective and randomized trial.