Christoph Schimmer

Prevention of sternal dehiscence and infection in high-risk patients: a prospective randomized multicenter trial.

BACKGROUND One factor for the development of sternal wound infection (SWI) is bony instability after sternotomy. This study compares two surgical techniques with respect to the occurrence of SWI in patients with an increased risk. METHODS In this multicenter study, 815 consecutive patients with an increased risk for SWI were prospectively randomly assigned to a conventional osteosynthesis (transsternal or peristernal wiring; n = 440) or to an osteosynthesis with additional lateral reinforcement (Robicsek; n = 375). Primary endpoints were the rate of sternal dehiscence as well as the occurrence of superficial sternal wound infections and deep sternal wound infections. RESULTS Both groups were comparable concerning preoperative and intraoperative variables. The rate of sternal dehiscence, superficial sternal wound infections, and deep sternal wound infections (conventional technique 2.5%, 3.4%, 2.5%; and Robicsek 3.7%, 5.6%, 3.7%) did not differ between the groups. Logistic regression analysis found independent risk factors for the development of sternal dehiscence: body mass indes greater than 30 kg/m(2) (odds ratio [OR]: 2.9; p = 0.05), New York Heart Association class more than III (OR: 2.4; p = 0.07), impaired renal function (OR: 3.9; p = 0.01), peripheral arterial disease (OR: 3.6; p = 0.001), immunosuppressant state (OR: 3.3; p = 0.001), sternal closure performed by an assistant doctor (OR: 2.5, p = 0.004), postoperative bleeding (OR: 4.2; p = 0.03), transfusion of more than 5 red blood units (OR: 3.7, p = 0.01), reexploration for bleeding (OR: 6.9, p = 0.001), and postoperative delirium (OR: 3.5, p = 0.01). There was an inverse relation between the numbers of wires and DSWI in patients with conventional sternal closure (p = 0.008). CONCLUSIONS In patients with an increased risk for sternal instability and wound infection after cardiac surgery, sternal reinforcement according to the technique described by Robicsek did not reduce this complication.

Sternal closure techniques and postoperative sternal wound complications in elderly patients

OBJECTIVE Postoperative sternal wound complications (PSWC) including deep sternal wound infection (DSWI) and sternal dehiscence (SD) cause significant morbidity and mortality. Elderly patients with several risk factors are particularly prone to suffer PSWC. METHODS We present (I) a subset of 86 patients, all aged > or =75 years out of 339 cardiac surgery patients prospectively randomised to receive either conventional sternal closure or a Robicsek type closure. Primary end-points were SD and DSWI; secondary end-points included a composite of clinical parameters; (II) we retrospectively assessed data of 54/5273 patients with mediastinitis regarding the influence of advanced age. In addition, we report an epidemiological overview of different sternal closure techniques. RESULTS (I) The Robicsek technique showed an impact on SD and DSWI, and several secondary end-points: ventilator support (p=0.03), postoperative blood loss (p=0.04), and chest pain >3 days (p=0.04). (II) A total of 54/5273 (1.02%) patients developed postoperative mediastinitis. Twelve out of 54 (22%) patients died within 6 months of the initial operation. Predictors of mortality were insulin-dependent diabetes mellitus (p=0.05), renal insufficiency (p=0.01), delayed sternal closure (p=0.05), ICU-stay >10 days (p=0.01), and methicillin-resistant Staphylococcus aureus (p=0.03) or fungal infection (p=0.02). CONCLUSIONS No statistical difference in sternal dehiscence or mediastinitis was found irrespective of whether the bilateral and longitudinal parasternal closure or the conventional peri/trans-sternal wiring technique was used, but there was an obvious, positive influence on sternal dehiscence, deep sternal wound infection, and clinical parameters. However, the study population is relatively small.

Ischemia-reperfusion injury–induced pulmonary mitochondrial damage

BACKGROUND Mitochondrial dysfunction is a key factor in solid organ ischemia-reperfusion (IR) injury. Impaired mitochondrial integrity predisposes to cellular energy depletion, free radical generation, and cell death. This study analyzed mitochondrial damage induced by warm pulmonary IR. METHODS Anesthetized Wistar rats received mechanical ventilation. Pulmonary clamping was followed by reperfusion to generate IR injury. Rats were subjected to control, sham, and to 2 study group conditions: 30 minutes of ischemia without reperfusion (IR30/0), or ischemia followed by 60 minutes of reperfusion (IR30/60). Pulmonary edema was quantified by wet/dry-weight ratio. Polarography determined activities of respiratory chain complexes. Mitochondrial viability was detected by using Ca(2+)-induced swelling, and integrity by citrate synthase assay. Enzyme-linked immunosorbent assay determined cytochrome C content. Mitochondrial membrane potential (ΔΨm) stability was analyzed by flow cytometry using JC1, inflammation by myeloperoxidase (MPO) activity, and matrix-metalloproteinase-9 (MMP-9) activity by gel zymography, respectively. RESULTS In IR30/60 rats, tissue water content was elevated from 80.6 % (sham) to 86.9%. After ischemia, ΔΨm showed hyperpolarization and rapid decline after uncoupling compared with controls. IR, but not ischemia alone, impaired respiratory chain function complexes I, II and III (p < 0.05). Mitochondrial viability (p < 0.001) and integrity (p < 0.01) was impaired after ischemia and IR, followed by mitochondrial cytochrome C loss (p < 0.05). Increased activation of MPO (p < 0.01) and MMP-9 (p < 0.001) was induced by reperfusion after ischemia. CONCLUSIONS Ischemia-related ΔΨm hyper-polarization induces reperfusion-associated mitochondrial respiratory chain dysfunction in parallel with tissue inflammation and degradation. Controlling ΔΨm during ischemia might reduce IR injury.

Preoperative serum h-FABP concentration is associated with postoperative incidence of acute kidney injury in patients undergoing cardiac surgery

BackgroundFatty acid binding protein (FABP) is an intracellular transport protein associated with myocardial damage size in patients undergoing cardiac surgery. Furthermore, elevated FABP serum concentrations are related to a number of common comorbidities, such as heart failure, chronic kidney disease, diabetes mellitus, and metabolic syndrome, which represent important risk factors for postoperative acute kidney injury (AKI). Data are lacking on the association between preoperative FABP serum level and postoperative incidence of AKI.MethodsThis prospective cohort study investigated the association between preoperative h-FABP serum concentrations and postoperative incidence of AKI, hospitalization time and length of ICU treatment. Blood samples were collected according to a predefined schedule. The AKI Network definition of AKI was used as primary endpoint. All associations were analysed using descriptive and univariate analyses.ResultsBetween 05/2009 and 09/2009, 70 patients undergoing cardiac surgery were investigated. AKI was observed in 45 patients (64%). Preoperative median (IQR) h-FABP differed between the AKI group (2.9 [1.7–4.1] ng/ml) and patients without AKI (1.7 [1.1–3.3] ng/ml; p = 0.04), respectively. Patients with AKI were significantly older. No statistically significant differences were found for gender, type of surgery, operation duration, CPB-, or X-Clamp time, preoperative cardiac enzymes, HbA1c, or CRP between the two groups. Preoperative h-FABP was also correlated with the length of ICU stay (rs = 0.32, p = 0.007).ConclusionsWe found a correlation between preoperative serum h-FABP and the postoperative incidence of AKI. Our results suggest a potential role for h-FABP as a biomarker for AKI in cardiac surgery.

Cardiac surgery and hematologic malignancies: a retrospective single-center analysis of 56 consecutive patients

OBJECTIVE Patients with a history of hematologic malignancies (HMs) are considered high-risk candidates for cardiac surgery. Increased perioperative rates of infections, thrombo-embolic complications, and bleeding disorders are reported. However, low patient numbers and lack of control groups limit all published studies. METHODS A total of 56 patients with a history of HM underwent cardiac surgery. As many as 29 patients suffered from non-Hodgkin lymphoma, five from Hodgkin disease, and 12 from myeloproliferative disorders, one from acute lymphatic leukemia, and nine from monoclonal gammopathy. Surgery consisted of coronary artery bypass grafting, valvular surgery or combination procedures. HM patients were matched to 142 controls. Matching criteria applied consisted of sex, age, main diagnosis, and co-morbidities. RESULTS In-hospital mortality was elevated in HM patients though not reaching significance (P = 0.7). HM patients demonstrated increased rates of vascular, pulmonary, infectious complications (P > 0.1), and transfusion requirements (P = 0.077). The long-term survival of HM patients was significantly impaired (P = 0.043). A history of irradiation or chemotherapy predisposed to postoperative respiratory insufficiency, acute renal failure, and an impaired long-term survival (P > 0.065). CONCLUSIONS Cardiac surgery in patients with a history of a malignant hematologic disorder might achieve acceptable results. However, a higher complication and mortality rate have to be anticipated. Patients with hematologic disorders and a history of either irradiation or chemotherapy appear to be at an increased risk to develop postoperative end-organ failure.

Cardiac Operations in the Presence of Meningioma

BACKGROUND We investigated the effect of concomitant intracranial meningiomas on perioperative and postoperative complications after cardiac operations. Also studied was the intraoperative and perioperative management and long-term outcome of such patients. METHODS We retrospectively evaluated 16 cardiac surgical patients with intracranial meningiomas between January 1996 and July 2007. Neurologic outcome, incidence of transient neurologic deficits, and long-term follow-up focusing on freedom from any cardiac or neurosurgical intervention were assessed. RESULTS Five men and 11 women with a concomitant diagnosis of intracranial meningioma underwent cardiac operations using extracorporeal circulation. One patient received additional edema prophylaxis by intravenous dexamethasone. All patients were discharged home in good physical condition. Data on long-term survival were available on 14 patients, with 12 alive. Postoperatively, 2 patients died from myocardial infarction at 26.8 months and 2 from metastatic colon cancer at 57.9 months. Perioperative neurologic disorders were observed in 2 patients, comprising one stroke after intervention for aortic dissection and one thromboembolic event 2 weeks after biologic mitral valve replacement due to anticoagulation disorders. No meningioma-related adverse event was observed. CONCLUSIONS The presence of intracranial meningioma does not appear to be a risk factor for patients undergoing cardiac operations. No meningioma-related neurologic sequelae were documented postoperatively. Neurosurgical consultation should be obtained in all patients preoperatively.

Prevention of surgical site sternal infections in cardiac surgery: a two-centre prospective randomized controlled study

OBJECTIVES Surgical site infection (SSI) of the sternum is a devastating complication in cardiac surgery. The aim of this prospective randomized controlled two-centre clinical study was to compare the use of a gentamicin-collagen sponge (Genta-Coll® resorb) and of a cyanoacrylate-based microbial skin sealant (InteguSeal®) on the SSI rate of the sternum. METHODS We analysed data from 996 consecutive patients following isolated coronary artery bypass grafting between 2012 and 2014. The patients were randomized into three groups: standard group (S-group), Genta-Coll group (G-group) and InteguSeal group (I-group). The primary study end-point was to analyse the incidence of superficial and deep sternal SSI. The secondary study end-point was to determine independent risk factors for an increased SSI rate. RESULTS Of the 996 patients investigated, 332 patients were in S-group, 336 patients in G-group and 328 patients in I-group. The mean age was 67.7 ± 9.4 years, 18.6% were women and the overall SSI rate was 6.2% with 2.2% deep sternal wound infections. SSI rates were 8.3% (S-group), 5.4% (G-group) and 4.9% (I-group) (P 0.16). Multiple regression analysis demonstrated a preoperative body mass index (BMI) of >30 kg/m2 (P 0.047), re-thoracotomy for postoperative bleeding (P < 0.001) and sternum instability (P < 0.001) as independent predictors for an increased SSI rate. CONCLUSIONS The application of InteguSeal® or Genta-Coll® resorb had no significant influence on the incidence of the sternal SSI rate in 996 consecutive cardiac surgery patients but demonstrated a trend towards a benefit from using these prophylactic approaches. Multiple regression analysis demonstrated a preoperative BMI of >30 kg/m2, re-thoracotomy for bleeding and sternum instability as independent predictors for an increased sternal SSI rate.

Cardiac surgery antibiotic prophylaxis and calculated empiric antibiotic therapy

Background Ongoing debate exists concerning the optimal choice and duration of antibiotic prophylaxis as well as the reasonable calculated empiric antibiotic therapy for hospital-acquired infections in critically ill cardiac surgery patients. Methods A nationwide questionnaire was distributed to all German heart surgery centers concerning antibiotic prophylaxis and the calculated empiric antibiotic therapy. Results The response to the questionnaire was 87.3%. All clinics that responded use antibiotic prophylaxis, 79% perform it not longer than 24 h (single-shot: 23%; 2 doses: 29%; 3 doses: 27%; 4 doses: 13%; and >5 doses: 8%). Cephalosporin was used in 89% of clinics (46% second-generation, 43% first-generation cephalosporin). If sepsis is suspected, the following diagnostics are performed routinely: wound inspection 100%; white blood cell count 100%; radiography 99%; C-reactive protein 97%; microbiological testing of urine 91%, blood 81%, and bronchial secretion 81%; procalcitonin 74%; and echocardiography 75%. The calculated empiric antibiotic therapy (depending on the suspected focus) consists of a multidrug combination with broad-spectrum agents. Conclusion This survey shows that existing national guidelines and recommendations concerning perioperative antibiotic prophylaxis and calculated empiric antibiotic therapy are well applied in almost all German heart centers.

The effectiveness of a motivation programme for lifestyle change in the course of aortocoronary bypass graft surgery

Objective: To evaluate the effectiveness of a motivation programme the motivation for lifestyle change in patients was measured before and after coronary artery bypass graft (CABG) surgery by comparing a usual care group with a group attending a motivation programme. Design: Prospective controlled study. Setting: University hospital cardiothoracic surgery department. Subjects: One hundred and forty patients (mean age 64.9; SD 8.5 years) who had an elective CABG surgery. Interventions: Each patient was evaluated regarding his or her motivation for lifestyle change two days before and 10 days after CABG surgery. Between January and May 2002 patients in usual care were investigated as a control group (n=70). From January to May 2003 patients had the opportunity to take part in a motivation programme that was provided by a trained clinical psychologist (n = 70). The programme consists of both personalized single sessions and group lectures. Measures: A 30-item questionnaire measuring the six factors Vulnerability, Intention, Social expectation, Outcome expectation, Self-efficacy expectation, and Perceived severity was developed. Results: ANOVA procedures with repeated measurements indicate significant effects in terms of higher motivation for lifestyle change in the treatment group in Vulnerability (F(1, 138) = 4.04; P=0.04), Intention (F(1, 138) = 19.81; P<0.001), Social expectation (F(1, 138)=21.97; P<0.001), Outcome expectation (F(1, 138) =17.95; P<0.001), and Self-efficacy expectation (F(1, 138) =14.31; P<0.001). Conclusions: This motivation programme performed in a cardiac surgery hospital after CABG may increase the motivation for a positive lifestyle change.

Impact of levosimendan and ischaemia–reperfusion injury on myocardial subsarcolemmal mitochondrial respiratory chain, mitochondrial membrane potential, Ca2+ cycling and ATP synthesis

OBJECTIVES Levosimendan (LS) is increasingly used in case of myocardial failure after cardiac surgery. The impact of LS on myocardial mitochondrial functions, such as respiratory chain function (RCF), mitochondrial membrane potential (ΔΨm), Ca(2+) handling, mitochondrial permeability transition pore (mPTP) opening and ATP during ongoing ischaemia/reperfusion (IR) injury, is not well understood. Depending on LS, I/R injury or the combination of both, we analysed myocardial functions in a retrograde Langendorff-model followed by the analysis of subsarcolemmal mitochondrial (SSM) functions. METHODS Rat hearts were divided into four study groups; two were subjected to 30 min of perfusion without (control) or with the application of 1.4 µmol/20 min LS (Levo). Experiments were repeated with hearts being subjected to 40 min of normothermic stop-flow ischaemia and 30 min of reperfusion without (IR) or with LS application (Levo-IR). Systolic left ventricular pressure (LVPsys), left ventricular contractility (LVdp/dtmax) and coronary flow were determined. SSM were analysed regarding RCF, ΔΨm, ATP, and Ca(2+) retention capacity (CRC), Ca(2+)-induced swelling and Ca(2+) fluxes after (re)perfusion. RESULTS I/R injury suppressed LVdp/dtmax (1381 ± 927 vs 2464 ± 913 mmHg/s; P = 0.01 at 30 min (re-)perfusion time). IR revealed complex I-V state3 (19.1 ± 7.4 vs 27.6 ± 11.0 nmolO2/min; P < 0.044) and II-V state3 (20.6 ± 6.8 vs 37.3 ± 9.10 molO2/min; P < 0.0001) suppression and Levo limited I-V (14.8 ± 11.1 vs 27.6 ± 11.0 nmolO2/min; P < 0.001) and II-V (24.1 ± 6.4 vs 37.3 ± 9.10 molO2/min; P < 0.0001) function. After energizing, ΔΨm hypopolarization was observed in Levo (0.76 ± 0.04 vs 0.84 ± 0.04; P = 0.02), IR (0.75 ± 0.06 vs 0.84 ± 0.04; P = 0.007) and Levo-IR (0.75 ± 0.06 vs 0.06 ± 0.04; P = 0.01). IR (AUC: 626 vs 292; P = 0.023) and Levo-IR (AUC: 683 vs 292, P = 0.003) increased Ca(2+)-induced mPTP-opening susceptibility. CRC declined in IR (6.4 ± 2.1 vs 10.5 ± 2.6; P = 0.04) or Levo (6.5 ± 2.0 vs 10.5 ± 2.6; P = 0.023). Ca(2+) uptake was delayed in IR and Levo-IR without LS impact (P < 0.0001). Ca(2+) liberation was increased in Levo-IR. ATP synthesis was reduced in Levo (0.49 ± 0.14 vs 0.74 ± 0.14; P = 0.002) and Levo-I/R (0.34 ± 0.18 vs 0.74 ± 0.14; P < 0.002). CONCLUSION LS limited RCF at complex IV and V with ΔΨm hypopolarization suggesting a specific [Formula: see text]-dependent pathway. Ca(2+) redistribution from SSM by LS during I/R injury possibly prevents from Ca(2+) overload due to mPTP flickering. LS-induced mPTP flickering did not promote permanent Ca(2+)-induced mPTP opening. LS-dependent inhibition of ATP generation presumably resulted from complex IV and V limitations and lowered ΔΨm. However, a resulting impact of limited ATP synthesis on myocardial recovery remains arguable.