Ernst Wolner

Transapical Minimally Invasive Aortic Valve Implantation: Multicenter Experience

Background— To evaluate initial multicenter results with minimally invasive transapical aortic valve implantation (TAP-AVI) for high risk patients with aortic stenosis. Methods and Results— TAP-AVI was performed via a small anterolateral minithoracotomy with or without femoro-femoral extracorporeal circulation (ECC) on the beating heart. A pericardial xenograft fixed within a stainless steel, balloon expandable stent (Edwards SAPIEN THV, Edwards Lifesciences) was used. Fifty-nine consecutive patients (81±6 years, 44 female) were operated on from 02/06 until 10/06 at 4 centers using fluoroscopic and echocardiographic visualization. Average EuroSCORE predicted risk for mortality was 27±14%. TAP valve positioning was performed successfully in 53 patients, 4 required early conversion to sternotomy. Implantation (23-mm valves in 19 and 26-mm valves in 40 patients) was performed on the beating heart during brief periods of rapid ventricular pacing. Thirty-one patients were operated on without cardiopulmonary bypass. Neither coronary artery obstruction nor migration of the prosthesis was observed, and all valves had good hemodynamic function. Echocardiography revealed minor paravalvular leakage in 26 patients (trace in 11, mild in 12, and severe in 3). Eight patients died in-hospital (13.6%) without any valve dysfunction. Actuarial survival was 75.7±5.9% at a follow-up interval of 110±77 days (range 1 to 255 days). Conclusions— TAP-AVI can be performed safely with good early results in high risk patients. Long-term valve performance as well as broader based applications of this promising approach will need to be studied.

Early failure of the tissue engineered porcine heart valve SYNERGRAFT in pediatric patients.

OBJECTIVES The first tissue engineered decellularized porcine heart valve, Synergraft (Cryolife Inc., USA) was introduced in Europe as an alternative to conventional biological valves. This is the first report of the rapid failure of these new grafts in a small series. MATERIALS AND METHODS In 2001, 2 model 500 and 2 model 700 Synergraft valves were implanted in four male children (age 2.5-11 years) in the right ventricular outflow tract as a root. Two patients had a Ross operation and two had a homograft replacement. RESULTS The cryopreserved Synergraft valves appeared macroscopically unremarkable at implantation. Recovery from surgery was uneventful and good valve function was demonstrated postoperatively. Three children died, two suddenly with severely degenerated Synergraft valves 6 weeks and 1 year after implantation. The third child died on the 7th day due to Synergraft rupture. Subsequently the fourth graft was explanted prophylactically 2 days after implantation. Macroscopically all four grafts showed severe inflammation starting on the outside (day 2 explant) leading to structural failure (day 7 explant) and severe degeneration of the leaflets and wall (6 weeks and 1 year explant). Histology demonstrated severe foreign body type reaction dominated by neutrophil granulocytes and macrophages in the early explants and a lymphocytic reaction at 1 year. In addition significant calcific deposits were demonstrated at all stages. Surprisingly pre-implant samples of the Synergraft revealed incomplete decellularization and calcific deposits. No cell repopulation of the porcine matrix occurred. CONCLUSION The xenogenic collagen matrix of the Synergraft valve elicits a strong inflammatory response in humans which is non-specific early on and is followed by a lymphocyte response. Structural failure or rapid degeneration of the graft occurred within 1 year. Calcific deposits before implantation and incomplete decellularization may indicate manufacturing problems. The porcine Synergraft treated heart valves should not be implanted at this stage and has been stopped.

One year follow-up of the multi-centre European PARTNER transcatheter heart valve study

Background Transcatheter aortic valve implantation (TAVI) has emerged as a new therapeutic option in high-risk patients with severe aortic stenosis. Aims PARTNER EU is the first study to evaluate prospectively the procedural and mid-term outcomes of transfemoral (TF) or transapical (TA) implantation of the Edwards SAPIEN® valve involving a multi-disciplinary approach. Methods and results Primary safety endpoints were 30 days and 6 months mortality. Primary efficacy endpoints were haemodynamic and functional improvement at 12 months. One hundred and thirty patients (61 TF, 69 TA), aged 82.1 ± 5.5 years were included. TA patients had higher logistic EuroSCORE (33.8 vs. 25.7%, P = 0.0005) and more peripheral disease (49.3 vs. 16.4%, P< 0.0001). Procedures were aborted in four TA (5.8%) and six TF cases (9.8%). Valve implantation was successful in the remaining patients in 95.4 and 96.4%, respectively. Thirty days and 6 months survival were 81.2 and 58.0% (TA) and 91.8 and 90.2% (TF). In both groups, mean aortic gradient decreased from 46.9 ± 18.1 to 10.9 ± 5.4 mmHg 6 months post-TAVI. In total, 78.1 and 84.8% of patients experienced significant improvement in New York Heart Association (NYHA) class, whereas 73.9 and 72.7% had improved Kansas City Cardiomyopathy Questionnaire (KCCQ) scores in TA and TF cohorts, respectively. Conclusion This first team-based multi-centre European TAVI registry shows promising results in high-risk patients treated by TF or TA delivery. Survival rates differ significantly between TF and TA groups and probably reflect the higher risk profile of the TA cohort. Optimal patient screening, approach selection, and device refinement may improve outcomes.

Inflammatory response and myocardial injury following coronary artery bypass grafting with or without cardiopulmonary bypass.

OBJECTIVE In coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB) the inflammatory response is suggested to be minimized. Coronary anastomoses are performed during temporary coronary occlusion. Inflammatory response and myocardial ischaemia need to be studied in a randomized study comparing CABG in multivessel disease with versus without CPB. METHODS Following randomization 30 consecutive patients received CABG either with (n=16) or without CPB (n=14). Primary study endpoints were parameters of the inflammatory response (interleukin (IL)-6, interleukin-10, ICAM-1, P-selectin) and of myocardial injury (myoglobin, creatine kinase-MB (CK-MB), troponin I) (intraoperatively, 4, 8, 16, 24 and 48 h after surgery). The secondary endpoint was clinical outcome. RESULTS The incidence of major (death: CABG with CPB n=1, not significant (n.s.)) and minor adverse events (wound infection: with CPB n=2, without CPB n=1, n.s. ; atrial fibrillation: with CPB n=3, without CPB n=2, n.s.) was comparable between both groups. The release of IL-6 was comparable during 8 h of observation (n.s.). Immediately postoperatively IL-10 levels were higher in the operated group with CPB (211.7+/-181.9 ng/ml) than in operated patients without CPB (104.6+/-40.3 ng/ml, P=0.0017). Thereafter no differences were found between both groups. A similar pattern of release was observed in serial measures of ICAM-1 and P-selectin, with no difference between both study groups (n.s.). Eight hours postoperatively the cumulative release of myoglobin was lower in operated patients without CPB (1829.7+/-1374. 5 microg/l) than in operated patients with CPB (4469.8+/-4525.7 microg/l, P=0.0152). Troponin I release was 300.7+/-470.5 microg/l (48 h postoperatively) in patients without CPB and 552.9+/-527.8 microg/l (P=0.0213). CK-MB mass release was 323.5+/-221.2 microg/l (24 h postoperatively) in operated patients without CPB and 1030. 4+/-1410.3 microg/l in operated patients with CPB (P=0.0003). CONCLUSIONS This prospective randomized study suggests that in low-risk patients the impact of surgical access on inflammatory response may mimic the influence of long cross-clamp and perfusion times on inflammatory response. Our findings indicate that multiregional warm ischaemia, caused by snaring of the diseased coronary artery, causes considerably less myocardial injury than global cold ischaemia induced by cardioplegic cardiac arrest.

Endovascular stent graft repair for aneurysms on the descending thoracic aorta

BACKGROUND The traditional treatment of aneurysms of the descending thoracic aorta includes posterolateral thoracotomy and aortic replacement with a prosthetic graft. In this study, we report our experiences and results in endovascular stent graft placement as an alternative to surgical repair. METHODS Between January 1989 and July 1997, a total of 68 patients (24 women) underwent replacement of the thoracic aorta. Mean age at operation was 51 years. Fifty-eight patients underwent conventional surgical treatment. All of these patients were suitable candidates for endovascular stenting; however, no stent graft material was available at the time of operation. Ten patients (1 chronic dissection, 9 atherosclerotic aneurysm) received in the past 8 months the first commercially manufactured endovascular stent graft. The mean diameter of the aneurysms in this group was 7 cm (range, 6 to 8 cm). Two stent patients were operated on using only spinal cord analgesia. All stent grafts were custom designed for each of the 10 patients. RESULTS The 30-day mortality in the conventional group was 31% versus 10% in the stent group. Mean length of intervention was 320 minutes in the conventional group versus 150 minutes in the endovascular group. Spinal cord injury occurred in 5 patients (12%) in the surgical group, whereas none of the stented patients developed any neurologic sequelae. Mean intensive care unit stay was 13 days, followed by a mean of 10 days on a ward in the first group compared to 4 days in the intensive care unit and 6 days on the ward in the stent group. One stent was required in 2 patients, two stents were required in 3 patients, and four stents were deployed in 5 patients of our series. Five patients required transposition of the left subclavian artery to achieve a sufficient neck for the proximal placement of the stent. There was complete thrombosis of the thoracic aortic aneurysm surrounding the stent graft in 8 patients (80%). Two patients required restenting as a result of leakage (20%). Stent graft placing was performed through the femoral artery in 8 patients, whereas access was only achieved through the abdominal aorta in 2 patients. CONCLUSIONS These preliminary results demonstrate that endovascular stent graft replacement might be a promising, cheaper, and safe alternative method in selected patients with descending thoracic aneurysms.

Tissue engineering of heart valves : Decellularized porcine and human valve scaffolds differ importantly in residual potential to attract monocytic cells

Background—Tissue-engineered or decellularized heart valves have already been implanted in humans or are currently approaching the clinical setting. The aim of this study was to examine the migratory response of human monocytic cells toward decellularized porcine and human heart valves, a pivotal step in the early immunologic reaction. Methods and Results—Porcine and human pulmonary valve conduits were decellularized, and migration of U-937 monocytic cells toward extracted heart valve proteins was examined in a transmigration chamber in vitro. Homogenized tissue specimens were size fractionated by SDS-PAGE. The decellularization procedure effectively reduced the migration of human monocytes toward all heart valve tissue. However, only the antigen reduction of human pulmonary valves abolished the monocytic response (wall, 0.88±0.19% versus 30.20±3.93% migrated cells [mean±SEM]; cusps, 0.10±0.06% versus 10.24±1.83%) and was significantly lower (P<0.05) than that of the decellularized porcine equivalent (wall, 5.03±0.14% versus 24.31±2.38%; cusps, 3.18±0.38% versus 10.24±1.83%). SDS-PAGE of the pulmonary heart valve tissue revealed that considerable amounts of proteins with different molecular weights that were not detected in the human equivalent remain in the decellularized porcine heart valve. Conclusions—We describe for the first time that the remaining potential of decellularized pulmonary heart valves to attract monocytic cells depends strongly on whether porcine or human scaffolds were used. These findings will have an important impact on further investigations in the field of heart valve tissue engineering.

First Clinical Experience With the DeBakey VAD Continuous-Axial-Flow Pump for Bridge to Transplantation

BACKGROUND A shortage of donor organs and increased numbers of deaths of patients on the waiting list for cardiac transplantation make mechanical circulatory support for a bridge to transplantation a standard clinical procedure. Continuous-flow rotary blood pumps offer exciting new perspectives. METHODS AND RESULTS Two male patients (ages 44 and 65 years) suffering from end-stage left heart failure were implanted with a DeBakey VAD axial-flow pump for use as a bridge to transplant. In the initial postoperative period, the mean pump flow was 3.9+/-0.5 L/min, which equals a mean cardiac index (CI) of 2.3+/-0.2 L. min(-1). m(-2). In both patients, the early postoperative phase was characterized by a completely nonpulsatile flow profile. However, with the recovery of heart function 8 to 12 days after implantation, increasing pulse pressures became evident, and net flow rose to 4.5+/-0.6 L/min, causing an increase of mean CI up to 2.7+/-0.2 L. min(-1). m(-2). Patients were mobilized and put through regular physical training. Hemolysis stayed in the physiological range and increased only slightly from 2. 1+/-0.8 mg/dL before surgery to 3.3+/-1.8 mg/dL 6 weeks after implantation. CONCLUSIONS The first clinical implants of the DeBakey VAD axial-flow pump have demonstrated the device to be a promising measure of bridge-to-transplant mechanical support.

The vacuum-assisted closure system for the treatment of deep sternal wound infections after cardiac surgery.

BACKGROUND The VAC system (vacuum-assisted wound closure) is a noninvasive active therapy to promote healing in difficult wounds that fail to respond to established treatment modalities. The system is based on the application of negative pressure by controlled suction to the wound surface. The method was introduced into clinical practice in 1996. Since then, numerous studies proved the effectiveness of the VAC System on microcirculation and the promotion of granulation tissue proliferation. METHODS Eleven patients (5 men, 6 women) with a median age of 64.4 years (range 50 to 78 years) with sternal wound infection after cardiac surgery (coronary artery bypass grafting = 5, aortic valve replacement = 5, ascending aortic replacement = 1) were fitted with the VAC system by the time of initial surgical debridement. RESULTS Complete healing was achieved in all patients. The VAC system was removed after a mean of 9.3 days (range 4 to 15 days), when systemic signs of infection resolved and quantitative cultures were negative. In 6 patients (54.5%), the VAC system was used as a bridge to reconstructive surgery with a pectoralis muscle flap, and in the remaining 5 patients (45.5%), primary wound closure could be achieved. Intensive care unit stay ranged from 1 to 4 days (median 1 day). Duration of hospital stay varied from 13 to 45 days (median 30 days). In-hospital mortality was 0%, and 30-day survival was 100%. CONCLUSIONS The VAC system can be considered as an effective and safe adjunct to conventional and established treatment modalities for the therapy of sternal wound infections after cardiac surgery.

Comparison of different decellularization procedures of porcine heart valves

Background Tissue engineering of heart valves should avoid the disadvantages of conventional prostheses. In this study we tested different decellularization procedures for their potential of cell removal and their ability to preserve the matrix. Methods Specimens of porcine aortic and pulmonary roots were treated with either trypsin or sodium-dodecyl-sulfate (SDS) or Triton-X 100® and sodium-deoxycholate with a range of concentrations. Tissue samples were then processed for scanning electron microscopy and laser scanning microscopy. Results Trypsin achieved only incomplete decellularization and caused severe structural alterations of the matrix. In contrast SDS removed cells completely but caused strong structural alterations. Treatment with Triton-X100® and sodium-deoxycholate achieved both complete decellularization and preservation of the matrix structure. Conclusion Techniques of decellularization are highly variable in efficiency and matrix preservation and was best achieved in our study with Triton-X100® and sodium deoxycholate.

Alpha-Gal on bioprostheses: xenograft immune response in cardiac surgery

Background  The α‐Gal (Galα1,3‐Galβ1–4GlcNAc‐R) epitope is the major xenoantigen causing hyperacute rejection of pig organs transplanted into primates. Porcine bioprostheses are utilized in cardiac surgery. However, premature degeneration of bioprostheses has limited utilization in younger patients and the immune response remains elusive. We sought to investigate whether a specific α‐Gal immune response may play a role in this clinical scenario.