Maximilian Scherner

Minimally invasive transapical aortic valve implantation and the risk of acute kidney injury.

BACKGROUND The new technique of minimally invasive transapical aortic valve implantation (TAP-AVI) deals with high-risk patients and despite the absence of cardiopulmonary bypass it might lead to renal impairment. The aim of this study was to estimate the risk of the development of acute kidney injury (AKI) after TAP-AVI and to identify possible risk factors with regard to the morbidity and mortality of the patients. METHODS Data of 30 consecutive patients undergoing TAP-AVI were recorded and followed up for 8 weeks. Postoperative AKI has been defined according to RIFLE criteria. Two patients on chronic hemodialysis have been followed up. RESULTS Of 28 patients, AKI occurred in 16 patients (57%). Statistical analysis revealed no influence on the risk of developing AKI caused by the dose of applicated contrast medium (p = 0.09), the patients age (p = 0.5), or the existence of diabetes (p = 0. 16). Analysis concerning the relationship between a preexisting coronary heart disease and AKI showed a tendency to be associated with a higher risk of the development of AKI (70% preexisting congenital heart disease in the AKI group versus 50%; p = 0.28). Only a preoperative serum creatinine greater than 1.1 mg/dL was a strong predictor for developing AKI (p < 0.01). Length of stay in the intensive care unit and the complete length of hospital stay revealed no difference with regard to postoperative development of AKI though statistical analysis showed a trend to a higher mortality in the AKI group (27% vs 6%); univariate analysis did not reach statistical significance (p = 0.13). CONCLUSIONS The TAP-AVI seems to be a feasible procedure for high-risk patients with a clear risk of developing AKI. Patients at risk should be identified and, if indicated, already preoperatively treated in collaboration with the attending nephrologists.

Current evidence of coronary artery bypass grafting off-pump versus on-pump: a systematic review with meta-analysis of over 16 900 patients investigated in randomized controlled trials†.

In the present systematic review with meta-analysis, we sought to determine the current strength of evidence for or against off-pump and on-pump coronary artery bypass grafting (CABG) with regard to hard clinical end-points, graft patency and cost-effectiveness. We performed a meta-analysis of only randomized controlled trials (RCT) which reported at least one of the desired end-points including: (i) major adverse cardiac and cerebrovascular events (MACCE), (ii) all-cause mortality, (iii) myocardial infarction, (iv) cerebrovascular accident, (v) repeat revascularization, (vi) graft patency and (vii) cost-effectiveness. The pooled treatment effects [odds ratio (OR) or weighted mean difference, 95% confidence intervals (95% CIs)] were assessed using a fixed or random effects model. A total of 16 904 patients from 51 studies were identified after literature search of the major databases using a predefined keyword list. The incidence of MACCE did not differ between the groups, neither during the first 30 days (OR: 0.93; 95% CI: 0.82-1.04) nor for the longest available follow-up (OR: 1.01; 95% CI: 0.92-1.12). While the incidence of mid-term graft failure (OR: 1.37; 95% CI: 1.09-1.72) and the need for repeat revascularization (OR: 1.55; 95% CI: 1.33-1.80) was increased after off-pump surgery, on-pump surgery was associated with an increased occurrence of stroke (OR: 0.74; 95% CI: 0.58-0.95), renal impairment (OR: 0.79; 95% CI: 0.71-0.89) and mediastinitis (OR: 0.44; 95% CI: 0.31-0.62). There was no difference with regard to hard clinical end-points between on- or off-pump surgery, including myocardial infarction or mortality. The present systematic review emphasizes that both off- and on-pump surgery provide excellent and comparable results in patients requiring surgical revascularization. The choice for either strategy should take into account the individual patient profile (comorbidities, life expectancy, etc.) and importantly, the surgeons experience in performing on- or off-pump CABG in their routine practice.

In vivo application of tissue-engineered blood vessels of bacterial cellulose as small arterial substitutes: proof of concept?

BACKGROUND Tissue-engineered blood vessels (TEBVs) represent an innovative approach for overcoming reconstructive problems associated with vascular diseases by providing small-caliber vascular grafts. This study aimed to evaluate a novel biomaterial of bacterially synthesized cellulose (BC) as a potential scaffold for small-diameter TEBV. METHODS Small-diameter blood vessels with a supramolecular fiber network structure consisting of tubular hydrogels from biodesigned cellulose were created using Gluconacetobacter strains and Matrix reservoir technology. BC tubes (length: 100 mm, inner diameter: 4.0-5.0 mm) were applied to replace the carotid arteries of 10 sheep for a period of 3 mo to gain further insights into (a) functional (in vivo) performance, (b) ability of providing a scaffold for the neoformation of a vascular wall and (c) their proinflammatory potential, and the (d) technical feasibility of the procedure. RESULTS Preoperative analysis revealed a bursting strength of the grafts of approximately 800 mm Hg and suture retention strength of 4-5 N. Postexplantation analysis showed a patency rate of 50% (n = 5) and physiological performance of the patent grafts at 4, 8, and 12 wk postoperatively, compared with native arteries. Histologic analysis revealed a neoformation of a vascular wall-like structure along the BC scaffold consisting of immigrated vascular smooth muscle cells and a homogeneous endothelialization of the inner graft surface without signs of prothrombogenic or inflammatory potential. Scanning electron microscopy revealed a confluent luminal endothelial cell layer and the immigration of vascular smooth muscle cells into the BC matrix. CONCLUSIONS BC grafts provide a scaffold for the neoformation of a three-layered vascular wall exhibit attractive properties for their use in future TEBV programs for cardiovascular surgery.

Outcomes after peripheral extracorporeal membrane oxygenation therapy for postcardiotomy cardiogenic shock: a single-center experience

BACKGROUND We assessed the short-term outcomes and predictors of 30-d mortality in patients requiring temporary, peripheral extracorporeal membrane oxygenation (ECMO) for postcardiotomy cardiac failure. METHODS The data were retrospectively obtained using our institutional patient database. All patients who had received peripheral ECMO support after surgery for acquired heart disease from 2006 to 2010 were included in the present study. The demographic and perioperative variables of the 30-d survivors and nonsurvivors were compared using the chi-square and t-test, and multivariate logistic regression analysis was performed to identify the predictors of 30-d all-cause mortality. RESULTS A total of 77 patients with a mean age of 60 ± 13 years were included in the present analysis. Successful weaning from peripheral ECMO was achieved in 62% after 79 ± 57 h of ECMO support. The overall 30-d mortality rate was 70%, and mortality was reduced to 52% in the patients in whom ECMO support could be weaned successfully. Age (per year) at ECMO implantation was the only independent preoperative predictor of 30-d mortality (odds ratio 1.09, 95% confidence interval 1.03-1.15; P = 0.003). In addition, greater lactate levels after 24 h of ECMO therapy, a longer duration of ECMO support, and the presence of any ECMO-related or gastrointestinal complications were independent predictive factors for 30-d mortality (P < 0.05). CONCLUSIONS ECMO therapy provides a valuable therapeutic strategy for postcardiotomy myocardial failure but is still limited by high complication rates with fewer than 30% of patients discharged from the hospital. Patient age appears to be an essential preoperative predictor for mortality, and the blood lactate level is a relevant marker for the assessment of efficient ECMO support.

Renal impairment and transapical aortic valve implantation: impact of contrast medium dose on kidney function and survival

OBJECTIVE Patients undergoing transapical aortic valve implantation (TA-AVI) are usually over 80 years old and have a high prevalence of chronic kidney disease. However, transcatheter valve therapies require the use of contrast injections with the risk of nephrotoxicity. The aim of this study was to evaluate post-operative kidney function and survival in patients with pre-existing renal impairment with regard to the amount of contrast media used during TA-AVI. METHODS From January 2008 to March 2011, 50 patients (52% females, mean age 80.7 ± 5.3 years) with a serum creatinine level of >1.3 mg/dl were investigated. Patients receiving a dose of <100 ml of a contrast agent (low-dose group, n = 24) were separated from those who received >100 ml of a contrast agent (high-dose group, n = 26). An acute contrast-induced nephropathy (CIN) was defined as a serum creatinine increase of 0.5 mg/dl or by >25% of a baseline value within 48 h from contrast medium administration. Patients in both groups had similar characteristics in terms of age, sex, body mass index and comorbidities. RESULTS The median pre-contrast creatinine was 1.67 (1.37-1.83) mg/dl in the low-dose group and 1.51 (1.26-1.98) mg/dl in the high-dose group (P = 0.76). The post-contrast creatinine at 48 h was 1.53 (1.33-2.05) and 2.29 (1.67-2.86) mg/dl in the groups receiving low- and high-dose contrast agents, respectively (P = 0.007). CIN occurred in 41.7% (n = 10) of patients in the low-dose contrast group and in 69.2% (n = 18) in the high-dose contrast group (P = 0.046). Haemodialysis is necessary for 16.7% of the low-dose group and 38.5% of the high-dose group (P = 0.12). Trends towards longer intensive care unit and hospital stay were seen in patients with an extensive use of contrast media [4.3 (2.5-6.5) vs. 5 (3-7.8) days and 12 (9-14.3) vs. 13 (9-18) days, P = 0.091 vs. P = 0.546, respectively]. Regarding death, 3-month and 3-year mortality were significantly higher in the high-dose group (8.3 vs. 30.8%, P = 0.036 and 25 vs. 61.5%, P = 0.004, respectively). CONCLUSIONS Our results indicate a possible association between higher CIN and mortality rate and the extensive use of contrast media during TA-AVI among high-risk patients with pre-existing renal impairment.

Meta-Analysis of Patients Taking Statins Before Revascularization and Aortic Valve Surgery

Statin intake before cardiac surgery is associated with favorable outcomes. We sought to analyze the evidence for statin pretreatment before isolated coronary artery bypass graft surgery and aortic valve replacement surgery. In this meta-analysis, we demonstrate beneficial results for the endpoints mortality, stroke, atrial fibrillation, and length of stay in hospital in 36,053 statin-pretreated coronary artery bypass graft surgery patients compared with control subjects retrieved from 32 studies, but fail to detect relevant advantages through preoperative statin therapy for 3,091 patients undergoing aortic valve replacement from four trials. Strict adherence to guidelines recommending statin treatment before CABG surgery is therefore mandatory.

Baroreflex activation therapy in patients with pre-existing implantable cardioverter-defibrillator: compatible, complementary therapies

AIMS The Neo™ System (CVRx) is an implantable device, CE certified for the treatment of resistant hypertension and investigationally used to treat systolic heart failure by electrical stimulation of the carotid baroreceptors. It is unknown whether interaction might exist between the Neo System and implantable cardioverter-defibrillators (ICDs). METHODS AND RESULTS Compatibility of the Neo device was tested in seven consecutive patients with pre-existing ICDs. Intra- and post-operative testing was completed with ICD and Neo settings programmed to provoke interaction. Intracardiac electrograms were printed to determine interaction with the ICD. Interaction testing during implantation and follow-up showed that there was no device-device interaction. No interaction was observed at maximum atrial and ventricular sensitivity settings and maximum Neo output settings. CONCLUSION Combined therapy with the Neo device and at least in this study reported that transvenous ICD systems can be performed safely.

Successful Transapical Aortic Valve Replacement in a Patient With a Previous Mechanical Mitral Valve Replacement

In this case we illustrate our experience with transapical minimal invasive aortic valve replacement in a patient who previously underwent mitral valve replacement. The implantation did not interfere with the existing prosthesis and could even be used as a further landmark, helping height positioning of the aortic valve.

Acute kidney injury after transcatheter aortic valve implantation

Even though experience and techniques have constantly improved over the last years, peri- and postprocedural complications in high risk TAVI-collectives remain a major issue affecting outcome and survival. Acute kidney injury (AKI) is a frequent complication after transcatheter aortic valve implantation (TAVI) and effects outcome and survival. However, the definition of AKI in published studies dealing with the phenomenon of AKI after TAVI varies widely and lacks standardization. This Review aims to present an overview over the current literature concerning AKI after TAVI with regard to the definition of AKI, the impact of AKI on mortality and potential risk factors for renal impairment after TAVI.

Transapical Valve Implantation and Resuscitation: Risk of Valve Destruction

In this article we illustrate our experience with the destruction of a transapically implanted aortic valve prosthesis due to postoperative cardiopulmonary resuscitation. The fact of the existing risk of the valve damage by chest compression during cardiopulmonary resuscitation should be taken into consideration when discussing the potential exposure of this technology to lower the risk for patients. Furthermore, we introduce a technique of less invasive cardiopulmonary resuscitation that offers the possibility of lowering the risk of compressing the valve.