Impact of Covid-19 on farming systems in Europe through the lens of resilience thinking.

Context: Resilience is the ability to deal with shocks and stresses, including the unknown and previously unimaginable, such as the Covid-19 crisis. Objective: This paper assesses (i) how different farming systems were exposed to the crisis, (ii) which resilience capacities were revealed and (iii) how resilience was enabled or constrained by the farming systems' social and institutional environment. Methods: The 11 farming systems included have been analysed since 2017. This allows a comparison of pre-Covid-19 findings and the Covid-19 crisis. Pre-Covid findings are from the SURE-Farm systematic sustainability and resilience assessment. For Covid-19 a special data collection was carried out during the early stage of lockdowns. Results and conclusions: Our case studies found limited impact of Covid-19 on the production and delivery of food and other agricultural products. This was due to either little exposure or the agile activation of robustness capacities of the farming systems in combination with an enabling institutional environment. Revealed capacities were mainly based on already existing connectedness among farmers and more broadly in value chains. Across cases, the experience of the crisis triggered reflexivity about the operation of the farming systems. Recurring topics were the need for shorter chains, more fairness towards farmers, and less dependence on migrant workers. However, actors in the farming systems and the enabling environment generally focused on the immediate issues and gave little real consideration to long-term implications and challenges. Hence, adaptive or transformative capacities were much less on display than coping capacities. The comparison with pre-Covid findings mostly showed similarities. If challenges, such as shortage of labour, already loomed before, they persisted during the crisis. Furthermore, the eminent role of resilience attributes was confirmed. In cases with high connectedness and diversity we found that these system characteristics contributed significantly to dealing with the crisis. Also the focus on coping capacities was already visible before the crisis. We are not sure yet whether the focus on short-term robustness just reflects the higher visibility and urgency of shocks compared to slow processes that undermine or threaten important system functions, or whether they betray an imbalance in resilience capacities at the expense of adaptability and transformability. Significance: Our analysis indicates that if transformations are required, e.g. to respond to concerns about transnational value chains and future pandemics from zoonosis, the transformative capacity of many farming systems needs to be actively enhanced through an enabling environment.

Platelet function analyzer (PFA-100) as a useful tool for the prediction of transfusion requirements during aortic valve replacement.

BACKGROUND: Shear stress-induced hemostatic abnormalities, particularly loss of the hemostatically most competent, highest molecular weight von Willebrand factor multimers, are common in patients with aortic valve stenosis. Although controversially discussed, these hemostatic defects might be associated with an increased risk of bleeding during aortic valve replacement. Since the determination of closure times with a platelet function analyzer is sensitive for the detection of defects of primary hemostasis including shear stress-induced von Willebrand factor abnormalities, this study was performed to evaluate a method to predict intraoperative transfusion requirements in this setting. METHODS: Fifty patients (mean age ± SD: 68 ± 9 years, range 40-85 years) admitted for aortic valve replacement were enrolled in the study. Closure times of epinephrine/collagen and ADP/collagen cartridges were determined with a platelet function analyzer in the absence of antiplatelet agents. Results were compared to those obtained in healthy individuals without medication. The probability that a patient would require a transfusion of packed red cells (RBC) and fresh frozen plasma (FFP) was calculated for each obtained closure time using a multiple regression model. RESULTS: Compared to controls, patients undergoing aortic valve replacement had a significantly higher incidence of prolonged closure in the platelet function analyzer. The prolonged closure time of both epinephrine/collagen and ADP/collagen cartridges was significantly correlated with intraoperative transfusion of RBC, but not FFP. CONCLUSIONS: In patients undergoing aortic valve replacement, prolongation of closure times as determined by a platelet function analyzer is frequently observed, indicating the presence of shear stress-induced defects of primary hemostasis. Since the prolongation of closure times is significantly correlated to the probability of intraoperative transfusion, this method might offer a significant contribution to the preoperative risk stratification of patients.

Vacuum-assisted wound closure is superior to primary rewiring in patients with deep sternal wound infection.

OBJECTIVE: Deep sternal wound infections are serious complications after cardiac surgery. The aim of the present study is to compare the outcome after vacuum-assisted wound closure to that after primary rewiring with disinfectant irrigation. The study additionally focuses on defining predictors for the failure of primary rewiring and its impact on postoperative outcome. METHODS: Retrospective analysis was performed in 5232 patients who underwent cardiac surgery with a median sternotomy. 192 patients postoperatively developed deep sternal wound infections and were distributed into 2 therapy groups: a vacuum-assisted wound closure (= VAC) group and a primary rewiring (= RW) group, which was subdivided into healing after rewiring (= RW-h) and failure of rewiring (= RW-f). These groups were compared statistically to reveal coincidental pre-, intra- and postoperative parameters. RESULTS: Compared to the VAC group, the RW group showed a poorer outcome, although RW baseline characteristics were apparently beneficial. Primary rewiring failed in 45.8 % of all cases, which led to even worse outcomes. Important predictors for failure of primary rewiring were morbid obesity, diabetes mellitus type II, chronic obstructive pulmonary disease, preoperatively impaired left ventricular function, postoperatively positive blood and wound cultures, bilateral harvesting of internal thoracic arteries and the need for surgical reexploration. CONCLUSIONS: In spite of patients being in a worse condition, vacuum-assisted wound closure therapy resulted in improved outcomes and thus should be preferred to primary rewiring. Moreover we report on predictors which may indicate whether there is a high risk of rewiring failure.

Heparin-induced thrombocytopenia type II after cardiac surgery: predictors and outcome.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a serious complication after cardiac surgery. The aim of the present study was to identify pre- and intraoperative predictors for the postoperative occurrence of HIT. The study additionally focused on the impact of HIT on postoperative outcome. METHODS: Retrospective analysis was performed for 5073 patients who had required extracorporeal circulation during cardiac surgery. Patients were divided into 3 groups: 1) patients who had postoperative HIT (HIT+); 2) patients with postoperative thrombocytopenia but without HIT (HIT-); and 3) patients with normal platelet count (C). The groups were statistically compared with regard to pre-, intra- and postoperative parameters. RESULTS: Statistically significant predictors were renal insufficiency, intravenous application of heparin for more than 3 days, previous percutaneous coronary intervention within the last 4 weeks, urgency/emergency operation, combined surgery, prolonged extracorporeal circulation or cross-clamping time, and low cardiac output syndrome. Postoperative HIT was associated with an enhanced risk of renal failure, infectious and thromboembolic complications and in-hospital mortality. CONCLUSION: Postoperative HIT increases morbidity and mortality. The predictors presented in this study can be used to identify patients at risk of developing HIT.

Early reintubation after cardiac operations: impact of nasal continuous positive airway pressure (nCPAP) and noninvasive positive pressure ventilation (NPPV).

BACKGROUND: Due to an increasing number of comorbidities there is still a significant incidence of respiratory failure after primary postoperative extubation in patients who undergo cardiosurgery. We wanted to study whether nCPAP could improve pulmonary oxygen transfer and avoid the necessity for reintubation after cardiac surgery. Additionally, we compared this protocol to noninvasive positive pressure ventilation (NPPV). PATIENTS AND METHODS: Over a period of 3 years we analyzed all patients who were extubated within 12 hours after cardiac surgery, and in whom pulmonary oxygen transfer (PaO2/FIO2) deteriorated without hypercapnia so that all these patients met predefined criteria for reintubation. There were three groups of patients: A = patients required immediate reintubation (n = 125); B = patients had nCPAP with intermittent mask CPAP (n = 264); and C = patients had NPPV (n = 36). RESULTS: 25.8 % of patients in Group B and 22.2 % of patients in Group C were also intubated after a period of CPAP or NPPV. All other patients of Groups B and C could be weaned from these devices (B: 33.4 ± 5.8 hours, C: 26.2 ± 4.2 h; P < 0.05) and were well oxygenated using a face mask at ambient pressures (PaO2/FIO2: B: 136 ± 12, C: 141 ± 12). In Group A, we found a higher mortality (8.8 %) than in Group B (4.2 %) and Group C (5.6 %). The ICU stay and in-hospital stay were significantly prolonged in Group A. The incidence of pulmonary infections (A: 24 %, B: 10.6 %, C: 13.8 %; P < 0.05) and the need for catecholamines were significantly increased in Group A, whereas nCPAP patients suffered significantly more often from impaired sternal wound healing (A: 4.8 %, B: 8.3 %; P < 0.05). CONCLUSIONS: We conclude that reintubation after cardiac operations should be avoided since nCPAP and NPPV are safe and effectively improve arterial oxygenation in the majority of patients with nonhypercapnic oxygenation failure. However, it is of great importance to pay special care to sternal wound complications in these patients.

Predictors of postoperative complications in octogenarians undergoing cardiac surgery.

OBJECTIVE: Aim of the study was to clarify the impact of different pre- and perioperative conditions on outcome in octogenarians undergoing cardiac surgery. METHODS: We retrospectively analyzed preoperative risk factors and intraoperative adverse events and studied in-hospital morbidity and mortality in 646 patients > or = 80 years of age (82.5 +/- 3.5 years) and in 6081 younger patients (70.3 +/- 3.4 years) who underwent cardiac surgery between 1/2001 and 12/2006. RESULTS: Preoperatively, octogenarians suffered significantly more from arterial hypertension, renal failure, previous neurological problems, unstable angina and NYHA class IV than younger subjects. The incidence of combined valve and coronary procedures and of urgent operations was also significantly higher in patients > or = 80 years (27.7 % vs. 18.2 %, P < 0.05, and 7.3 % vs. 4.2 %, P < 0.05, respectively). In-hospital mortality was higher (7.4 % vs. 3.7 %, P < 0.05), and average ICU and total in-hospital stay was longer in the older age group. Postoperative complications occurred in 15 % of patients > or = 80 years compared to 7.6 % of patients < or = 79 years ( P < 0.05). NYHA class IV, female sex and preoperative renal failure correlated with perioperative morbidity. Multivariate analysis could identify urgent procedures, redo surgery, mitral valve surgery and prolonged cross-clamping times as predictors of mortality. CONCLUSIONS: Cardiac surgery in octogenarians can be performed with an acceptable risk but an increased mortality and morbidity compared to younger patients. High-risk octogenarians, who require intensive perioperative management, should be identified to reduce the incidence of postoperative complications.

Platelet-function analyzer closure times indicate shear stress-induced hemostatic abnormalities in patients with aortic valve stenosis and correlate with perioperative transfusion requirements.

BACKGROUND: Shear stress-induced hemostatic abnormalities are highly prevalent in patients with aortic valve stenosis. In this study, we determined closure times with a platelet-function analyzer (PFA-100, Dade Behring, Marburg, Germany) in patients admitted for aortic valve replacement to assess the correlation with the severity of aortic valve stenosis, blood loss, perioperative transfusion requirements, and need for re-thoracotomy. PATIENTS AND METHODS: Fifty consecutive patients (mean age [+/- SD] 68 +/- 9 years) were enrolled. Closure times of epinephrin/collagen and adenosine diphosphate (ADP)/collagen cartridges were determined at least ten days after discontinuation of antiplatelet medication and compared to those of healthy control subjects without medication. RESULTS: Closure times of epinephrin/collagen (210 +/- 69 sec vs. 140 +/- 50 sec, p < 0.0001) and ADP/collagen (145 +/- 58 sec vs. 108 +/- 45 sec, p < 0.0001) cartridges were prolonged in patients with aortic valve stenosis. Intraoperative transfusion of red blood cell units was associated with the closure times of epinephrin/collagen (r = 0.28, p = 0.04) and ADP/ collagen cartridges (r = 0.28, p = 0.04). Total transfusion of red blood cell units was associated with ADP/ collagen closure times (r = 0.31, p = 0.02), but not epinephrin/collagen closure times (r = 0.26, p = 0.07). No significant association of closure times with intraoperative, postoperative and total transfusion of fresh frozen plasma units was observed. CONCLUSIONS: Prolongation of closure times determined with a platelet-function analyzer is highly prevalent in patients with aortic valve stenosis and appears to reflect shear stress-induced hemostatic abnormalities. Since prolonged closure times are associated with increased perioperative transfusion of red blood cell units, the assay could significantly contribute to the identification of individuals at risk.

Cardiac valve replacement in patients with end-stage renal failure: impact of prosthesis type on the early postoperative course.

BACKGROUND: It is still unclear whether biological or mechanical valves should be preferred in patients on chronic dialysis therapy. PATIENTS AND METHODS: We retrospectively analyzed data from 104 patients (66.5 +/- 8.6 years) with end-stage renal failure (RF) who underwent aortic or mitral valve replacement between 2002 and 4/2008. Mechanical valves were implanted in 44 (42 %) patients and bioprostheses in 60 (58 %). The two groups were comparable with regard to preoperative data, age and incidence of additional CABG procedures. We studied in-hospital morbidity and mortality, major postoperative complications and length of ICU and hospital stay. Additionally, parameters predicting a poor outcome were analyzed with multivariate regression analysis. RESULTS: The overall hospital mortality was 12.5 % and did not differ between the two groups (mechanical: 13.6 %, biological: 11.7 %, n. s.). In the postoperative course, duration of ventilation and ICU stay were similar, whereas hospital stay was significantly longer for patients with mechanical prostheses (19.5 +/- 5.4 vs. 15.6 +/- 4.1 days, P < 0.05). Mechanical valve patients had a significantly higher rate of postoperative cerebrovascular incidents (18.2 vs. 8.3 %, P < 0.05) and bleeding complications (15.9 vs. 11.7 %, P < 0.05). Reoperation, obesity, left ventricular ejection fraction < 30 % and previous neurological complications were independent predictors of hospital mortality. CONCLUSIONS: Our results demonstrate that in patients with end-stage RF, the use of mechanical valves is associated with a significant risk of complications. Because of the poor overall survival of patients on dialysis, bioprosthesis degeneration will not be a limiting factor. Therefore, preference should be given to biological valves in these patients.

The impact of pre- and postoperative renal dysfunction on outcome of patients undergoing coronary artery bypass grafting (CABG).

OBJECTIVE: Acute changes in renal function after elective coronary bypass surgery represent a challenging clinical problem. In this study, we evaluated perioperative risk factors for the development of postoperative renal dysfunction (PRD), and the impact of such an event on the perioperative course. Additionally, we investigated the influence of preoperatively mildly increased serum creatinine on perioperative mortality and morbidity. METHODS: We retrospectively analyzed data of 2511 patients undergoing isolated CABG between 2004 and 2007 with a preoperative serum creatinine < or = 2.2 mg/dL. There were 592 patients with a preoperative serum creatinine of between 1.4 and 2.2 mg/dl (mild renal dysfunction group) and 1919 patients with a serum creatinine < 1.4 mg/dl. Perioperative risk factors for PRD were analyzed by multivariate regression analysis. RESULTS: Global in-hospital mortality was 3.1 %.The incidence of PRD was 6.2 %. Mortality for patients who had PRD was 7.8 vs. 2.9 % for patients who did not ( P < 0.05). PRD increased the length of hospital stay by 3.7 days (12.2 vs. 15.9; P < 0.05). Multivariate logistic regression identified the following variables as independent predictors of PRD: age, angina class III/IV, diabetes mellitus, prolonged cardiopulmonary bypass time, and preoperative serum creatinine. With regard to preoperative renal function, we found that operative mortality was higher in the mild renal dysfunction group (5.7 % vs. 2.5 %; P < 0.05). New dialysis/hemofiltration (5.1 % vs. 1.2 %; P < 0.05) and postoperative stroke (5.1 % vs. 1.6 %; P < 0.05) were also more common in these patients. CONCLUSIONS: Mild renal dysfunction preoperatively is an important predictor of outcome after CABG. In these patients, PRD dramatically increases mortality, morbidity and length of hospital stay.

Predictors and outcome of ICU readmission after cardiac surgery.

OBJECTIVE: Readmission to the intensive care unit (ICU) after cardiac surgery is associated with higher costs and may be correlated with an increased mortality. We wanted to evaluate predictors of ICU readmission and to analyze the outcome of those patients. METHODS: 3523 patients who underwent CABG and/or valve surgery between 2004 and 2007 were reviewed retrospectively. The reasons for readmission and the postoperative course were analyzed. Furthermore, perioperative risk factors for readmission were determined by multivariate regression analysis. RESULTS: Of the 3374 patients discharged from the ICU, 5.9 % (198) of patients required a second stay in the intensive care (group r). The readmission rate was 4.8 % following CABG and 8.9 % following valve +/- CABG ( P < 0.05). The mean interval from ICU discharge to readmission was 3.3 +/- 6.2 days. Of the patients who were not readmitted, 1.3 % died in hospital, compared to 14.4 % in group r ( P < 0.05). After readmission, the mean length of stay in the ICU and in hospital was 7.1 +/- 5.9 and 21.3 +/- 11.1 days (3.1 +/- 1.2 and 13.1 +/- 5.1 days for all other patients [ P < 0.05]). Main reasons for readmission were respiratory failure (59 %), cardiovascular instability (25 %), renal failure (6.5 %), cardiac tamponade/bleeding (6 %), gastrointestinal complications (2 %) and sepsis (1.5 %). Multivariate logistic regression analysis revealed that preoperative renal failure, mechanical ventilation > 24 h, reexploration for bleeding and low cardiac output state were independent predictors for readmission. CONCLUSIONS: Patients after valve/combined surgery are more likely to require readmission to the ICU. Respiratory complications were the most common reasons for readmission. To reduce the readmission rate, it is necessary to treat cardio-respiratory problems early, particularly in patients showing predictive risk factors.

Intraaortic balloon pumping in patients with right ventricular insufficiency after cardiac surgery: parameters to predict failure of IABP Support.

BACKGROUND: The indications for intra-aortic balloon pump (IABP) in the case of a failing right ventricle after operations with extracorporeal circulation (ECC) are still discussed controversially. We investigated the benefit of IABP in patients with a predominantly right ventricular dysfunction after ECC. Additionally, we wanted to identify early and easily available prognostic markers for outcome in all patients receiving IABP support. PATIENTS AND METHODS: Between 1/2004 and 1/2008, 4550 patients underwent cardiac surgical procedures with ECC, 223 of whom (4.9 %) had an IABP inserted intra- or postoperatively (group 1). 79 of these patients were treated intraoperatively with IABP for early postoperative low cardiac output syndrome (LCOS) characterized by predominantly right ventricular failure (RV group). Clinical data and hemodynamic variables were recorded perioperatively. Multiple potential markers of mortality and postoperative complications were analyzed statistically, especially with regard to their predictive ability. RESULTS: 68 % of all IABP patients were successfully weaned from IABP support and 63 % survived to hospital discharge. In the RV group, cardiac index (CI) and mean arterial pressure (MAP) increased (CI 1.8 +/- 0.2 to 2.8 +/- 0.2, MAP 53 +/- 10 to 73 +/- 8, P < 0.05) within 1 hour after IABP, whereas central venous pressure (CVP) and pulmonary artery wedge pressure (PAWP) decreased ( P < 0.05). 59 patients in the RV group (75 %) could be weaned from IABP successfully and 69 % survived to hospital discharge. Serum lactate of more than 11 mmol/L in the first 10 hours of IABP support predicted a 100 % mortality. A base deficit of more than 12 mmol/L, mean arterial pressure less than 55 mmHg, urine output of less than 50 ml/h for 2 hours, and dose of epinephrine or norepinephrine of more than 0.4 mg/kg/min were other highly predictive prognostic markers. Furthermore, multivariate analysis showed that patients with a left atrial pressure > 17 mmHg or a mixed venous saturation (SVO (2)) < 65 % had poor outcomes. CONCLUSIONS: In patients with IABP support for postcardiotomy cardiogenic shock, elevated serum lactate, elevated base deficit, hypotension, oliguria and large vasopressor doses are all predictors of mortality. In these patients, the use of another mechanical assist device should be considered in good time. Our study additionally shows that LCOS caused by predominantly right ventricular failure - particularly after CABG - may be an additional indication for IABP.

Intermediate coronary revascularization using the Deltastream blood pump: results from an experimental study.

BACKGROUND: Myocardial revascularization using a complete heart-lung machine may involve many problems, as do complete off-pump attempts. Thus, it was the aim of this study to evaluate the effects of intermediate on-pump/off-pump myocardial revascularization using the miniaturized Deltastream blood pump, on ischemia and hemolysis, in comparison with standard myocardial revascularization. METHODS: In a group of 8 mini-pigs, combined on-pump/off-pump myocardial revascularization was performed using the Deltastream blood pump as beating-heart support for the on-pump part of the operation (group A). Seven other animals served as controls and underwent standard myocardial revascularization with the same device as integrated pump of a complete heart-lung machine (group B). Blood samples for blood gas metabolism, creatine kinase (CK), troponin I, lactate dehydrogenase (LDH), and hydroxybutyrate dehydrogenase (HBDH) were taken before and after the entire operation. RESULTS: Comparing the baseline values, the increase of CK was more pronounced in group B than in group A (176.4-/+41.2 to 279.7-/+29 U/L vs. 274-/+142.7 to 288.1-/+118.6 U/L, respectively; p=0.0006). Increase of troponin I was significantly higher in group B than in group A (1-/+0.3 to 2.9-/+1 ng/mL vs. 1.1-/+0.9 to 3-/+3.8 ng/mL, respectively; p=0.002). LDH increase was also more pronounced in group B (231.7-/+54.3 to 299.9-/+39.8 U/L vs. 274.9-/+59.7 to 263.8-/+57.9 U/L, respectively; p=0.01). HBDH values increased significantly in group B after the operation (group A: 215.9-/+34.7 to 200-/+39.2 U/L vs. group B: 195.4-/+41.7 to 274.9-/+51.6 U/L; p=0.02). Hemodynamic measures and LDH values under luxation (group A: 1.9-/+0.6 U/L; B: 3.5-/+1 U/L,p=0.001) were also superior in the study group. CONCLUSION: The current set-up might be superior to conventional extracorporeal circulation and thus be an alternative for high-risk candidates to avoid the adverse events of a complete heart-lung machine, when they are scheduled for complete myocardial revascularization.

CABG-procedures in patients with pretreatment with the GPIIb/IIIa-receptor antagonist tirofiban (Aggrastat): modification of perioperative management?

In order to investigate the effects of tirofiban administration in cardiac surgery all patients undergoing coronary artery bypass grafting (CABG) which received this drug preoperatively between 1/2002 and 6/2005 (n=232) were studied. Three groups regarding the perioperative administration of antifibrinolytic drugs were compared: group A=controls (n=70), group B=aprotinin (n=110), group C=tranexamic acid (n=52) Furthermore we could differ the patients depending on the time when tirofiban was stopped (<2 h, 2-4 h, >4 h preoperatively). The postoperative blood loss was significantly higher in all tirofiban-patients (A-C) compared to a group of CABG-patients without tirofiban. The best results concerning blood loss, transfusion of red cell concentrates (rcc), fresh frozen plasma (ffp) and incidence of re-sternotomy could be found in patients with aprotinin. A further significant improvement could be seen in patients who received platelets, intraoperative hemofiltration and in which tirofiban was stopped >4 h preoperatively. We conclude that by early presurgical discontinuing of tirofiban-therapy and slight modifications of the perioperative management bleeding complications can significantly be reduced.

Predictive risk factors in double-valve replacement (AVR and MVR) compared to isolated aortic valve replacement.

BACKGROUND: The operative risk of combined aortic and mitral surgery is still between 5 and 13 %, whereas isolated AVR normally causes complications in less than 4 % of all patients. Thus, it was the aim of the study to compare both procedures and to evaluate risk stratification in our patient cohort. PATIENTS AND METHODS: The inhospital mortality and complication rates were analyzed in both groups over a period of 4 years. There were 396 patients with isolated AVR, and 98 patients with AVR and MVR. For both groups, we investigated 16 possible risk factors for perioperative death or severe complications, such as low cardiac output syndrome (LCOS). The risk factors were analyzed by univariate analysis, and factors with P < 0.01 were entered into a multivariate analysis. RESULTS: There were 11/396 perioperative deaths in patients with AVR (2.8 %) compared to 5/98 (5.1 %) in DVR. The incidence of major complications was 5.3 % in AVR vs. 11.2 % in DVR. As risk factors ( P < 0.05) for death, we found in AVR: former cardiac surgery, aortic stenosis, and pulmonary arterial pressure > 55 mmHg. In patients with DVR, we additionally found: left atrial pressure (LAP) > 20 mmHg and creatinine > 2 mg/dl. Risk factors for severe complications in AVR were: former cardiac surgery and creatinine > 2 mg/dl, in cases of DVR, additionally: tricuspid valve disease (TVD) and LAP > 20 mmHg. CONCLUSIONS: Our analysis of risk factors shows that in patients with DVR preoperative parameters, which sometimes are estimated to be unimportant, may cause an adverse outcome. The operation should be carried out before reaching advanced or even end-stage heart failure, and more attention should be paid to an individual perioperative concept and optimized myocardial protection in such patients.

Intraaortic balloon pump counterpulsation after implantation of infrarenal and thoracoabdominal aortic protheses.

Highly complex vascular surgery interventions have nowadays become possible due to sophisticated operative techniques and modern intra- and postoperative anesthesiological strategies. Accordingly, the number of high risk vascular surgery interventions rises continuously and thus, the number of secondary complications after high risk interventions increases as well and requires likewise extraordinary treatment concepts. We report of a 68-year old patient who 6 months previously was operated on a ruptured abdominal aneurysm, before he was admitted to our institution for the treatment of a type IIIb (Crawford classification) thoracoabdominal aneurysm. Intraoperatively we implanted a 26 mm Dacron prosthesis which was anastomosed with the previously existing infrarenal graft. Postoperatively the patient suffered from a hemodynamically significant myocardial infarction and acute coronary catheter intervention was necessary. However, circulatory stability could not be reestablished by interventional measures and we therefore decided to implant the intraaortic balloon pump despite the presence of two synthetic aortic grafts. However, the chance of success of such a manoeuver as well as the effectiveness of intraprosthetic counterpulsation was unclear and our literature research undertaken to predict the risk of such a manouver was unsatisfactory. We therefore want to report this case and compile the literature dealing with perceptions and complications of intraaortic counterpulsation after the implantation of synthetic aortic prostheses, since such a treatment option comes to an increased clinical application in comparable constellations.

Ventricular constraint in dilated cardiomyopathy: a new, compliant textile mesh exerts prophylactic and therapeutic properties.

BACKGROUND: Dilated cardiomyopathy is associated with a progressive decrease in cardiac function, leading to end-stage heart failure. We aimed to stop this process by mechanically constraining the heart with a new, compliant textile mesh. METHODS: In 16 male Munich minipigs (50 +/- 7 kg), dilated cardiomyopathy with congestive heart failure was induced through 4 weeks of rapid ventricular pacing (220 beats/min). In the early-mesh group (n = 8), a polyvinylidene fluoride mesh was positioned around both ventricles before pacing was started. In the other group (n = 8), experimental dilated cardiomyopathy through rapid pacing was induced (no mesh). After mesh grafting, rapid pacing was continued (late mesh). RESULTS: Rapid pacing in the no-mesh group (control group) significantly decreased both systolic (cardiac output, peak systolic pressure, and the derivative of pressure increase [dP/dt(max)]) and diastolic (minimum rate of pressure rise [dP/dt(min)] and left ventricular end-diastolic pressure) variables, whereas these variables remained almost unchanged in the early-mesh group. In the late-mesh group the passive-elastic constraint not only prevented further deterioration but even exerted reverse remodeling to some extent (dP/dt(max) and left ventricular end-diastolic pressure, P < .05). CONCLUSIONS: Ventricular constraint with the new mesh seems to be a prophylactic and therapeutic option in cardiac insufficiency caused by ventricular dilation. This passive-elastic cardioplasty induced reverse remodeling of dilated hearts and significantly improved diastolic and systolic ventricular function.

Hemodynamic performance and clinical consequences of aortic valve replacement with 21-mm sized pericardial bioprostheses.

BACKGROUND: Aortic valve replacement (AVR) with a 21-mm sized bioprothesis is still discussed controversially. Since better results have been reported for pericardial valves, the aim of the current study was to analyze the hemodynamic performance as well as clinical parameters in our patients and to compare pericardial and standard porcine valves in particular. METHODS: 342 patients underwent AVR with a bioprosthesis between 1987 and 2000. A 21 mm prosthesis was used in 39 patients (group S), while 303 patients received at least a 23-mm sized valve (group L). Group S was further divided into 19 patients with a pericardial valve (group S1) and 20 patients with a standard porcine valve (group S2). The hemodynamic and clinical parameters were studied in all three groups. RESULTS: The peak and mean transprosthetic gradients were significantly lower in the pericardial group than in the porcine group, particularly between patients with 21 mm valves (peak/mean: S1: 24 +/- 9/20.8 +/- 6.5 mm Hg vs. S2: 38 +/- 15/33 +/- 9 mm Hg, p < 0.05) at discharge. We could also observe that the peak transprosthetic gradient 7 days postoperatively was not significantly higher in patients with a 21 mm pericardial valve compared to group L patients. Comparing clinical parameters, we found significantly more cerebral ischemic events, a prolonged mechanical ventilation, a higher mortality and a longer stay in hospital in the group S2 compared to the group S1. CONCLUSION: The current study shows that pericardial valves perform well, particularly in patients with small aortic roots. Postoperative hemodynamics and clinical results were better than for comparable standard porcine valves. As the outcome of patients with a 21 mm pericardial valve was no worse than that in patients with bigger valves, enlarging procedures for the aortic root are not necessary in the majority of these patients.

Neurological complications after cardiac surgery: risk factors and correlation to the surgical procedure.

OBJECTIVE: The aim of our study was to analyze risk factors for neurological complications in a group of patients undergoing cardiac operations. METHODS: We analyzed 783 consecutive patients undergoing cardiac surgery in 2001. Group I consisted of 582 patients with a CABG procedure, group II patients underwent a single valve replacement (n = 101), group III had a combined procedure (CABG + valve) (n = 70), and group IV patients underwent multi-valve procedure (n = 30). Forward stepwise multiple logistic regression analysis was used for statistical evaluation of independent risk factors for neurological complications (reversible deficits and strokes). RESULTS: The incidence of perioperative neurological problems was 1.7 % in the CABG group, 3.6 % in group II, 3.3 % in group III, and 6.7 % in group IV. With multivariate analysis we could identify various parameters as independent risk factors: previous neurological events, advanced age, and the time of aortic cross-clamping correlated with the incidence of perioperative neurological complications. In addition, we found a predictive value for preoperative anemia, the number of bypasses, an ejection fraction < 0.35 and for insulin-dependent diabetes mellitus. The duration of extracorporeal circulation and the fact of an re-operation could not be identified as risk factors. CONCLUSION: Our results show that type of surgery, symptomatic cerebrovascular disease, advanced age, diabetes mellitus, and probably aortic atheroma represent the most important risk factors for neurological complications. After preoperative consideration of the individual risk of each patient, neuroprotective interventions (arterial line filtration, alpha-stat management) and pharmacological neuroprotection may offer an improved outcome to some of these "high-risk" patients.