Objective: Stroke after CABG-procedures is a rare but devastating complication that leads to excess morbidity and mortality. The role of a significant carotid stenosis in the pathogenesis of this complication should be examined critically.

Objectives: Apoplexy is one of the major complications related to extracorporeal circulation (ECC). A model to preoperatively evaluate the impact of different ECC settings would be worthwile to choose conditions under which the individual risk of apoplexy is marginal.

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.

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.

Objective: To investigate the role of endothelial activation in the inflammatory response after CPB we looked for correlations between cytokine-/complement-levels, endothelial and clinical parameters.

Blood flow in human aorta and its major branches is analyzed by computational fluid dynamics, for physiologic and extracorporeal circulation, the latter being the main focus. Mainly, a steady-state analysis is applied corresponding to extracorporeal circulation conditions. For physiologic circulation, pulsatile flow is also investigated. Distensibility of aorta walls is neglected. Blood is modeled as Newtonian fluid. The SST model is employed for turbulence in all cases, for a coherent treatment of the flows exhibiting Reynolds numbers encompassing the transitional regime. For modeling outlet boundary conditions, a simple model based on the prescription of loss coefficients is proposed, which is believed to be more favorable than some more straightforward techniques such as the prescription of an outlet pressure. For physiologic circulation, it is observed that the time-averaged velocity field of pulsatile flow does not show remarkable differences to steady-state results. For extracorporeal circulation, two cases, namely an antegrade and a retrograde perfusion are investigated. Flow patterns observed for the physiologic circulation and the extracorporeal circulation techniques show considerable differences. For extracorporeal circulation, much larger wall shear stress values are predicted. This indicates that mobilization of arteriosclerotic plaques needs to be considered as a very important issue for the extracorporeal circulation.

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.

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.

Objective: We performed this study to determine the impact of HIT on outcome after cardiac surgery and to identify preoperative risk factors correlating with the incidence of HIT.

In cardiovascular medicine and coronary intervention, the intraaortic balloon pump (IABP) is a proven technology that plays an important role in circulatory support. The balloon pump invasively supports patient hemodynamics by augmenting diastolic perfusion and increasing diastolic blood pressure, thereby increasing coronary perfusion and reducing afterload. Its efficacy has been demonstrated in a multitude of clinical situations, including acute coronary syndromes, high-risk coronary interventions, cardiogenic shock, and cardiovascular surgery. The potential complications of aortic counterpulsation are serious, although much lower than in former times. With proper patient selection, insertion technique, and management, the IABP is a powerful device to assist in the treatment of patients with cardiovascular disease. Hemodynamics, indications, complications, and results associated with IABP use are reviewed.

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.

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 non-hypercapnic oxygenation failure. However, it is of great importance to pay special care to sternal wound complications in these patients.

Objective: A new and effective method- the vacuum assisted wound closure (VAC) – was introduced for the treatment of sternal wound infections (SWI) following cardiac surgery. We performed an analysis to determine whether clinical factors can predict which therapy – debridement and rewiring or VAC – should be utilized to treat SWI.

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.

Trotz zahlreicher Weiterentwicklungen der Herz-Lungen-Maschine (HLM) in den letzten Jahrzehnten ist unfraktioniertes Heparin nach wie vor der Goldstandard für die intraoperative Antikoagulation.

Extracorporeal circulation is a standard technique in cardiac surgery. Nevertheless, many different variations have been developed. Using computational fluid dynamics the impact of a particular perfusion technique can be simulated preoperatively. The aim of our study was to examine changes of the blood flow characteristics when perfusing the aorta with different techniques. At first we created a numerical model of a human aorta and its outlets. Then we performed simulations of antegrade pulsatile and non-pulsatile blood flow and simulated antegrade and retrograde perfusion via extracorporeal circulation canulas. At perfusion originating from canulas the flow became turbulent and its speed regionally increased up to 3,54 m / s. Otherwise perfusing retrogradely only marginal blood flow remained in the ascending aorta. Canula stream caused up to ten-fold higher local wall shear stress values, especially in the vessel roots next to the canulas and in the proximate aortic wall. Under these conditions mobilization of arteriosclerotic plaques has to be considered. Our study shows that antegrade and retrograde perfusion via canulas change important blood flow characteristics as flow speed, turbulent stream and wall shear stress.

Objectives: Extracorporeal circulation is a standard technique in cardiac surgery. Nevertheless, many different variations have been developed. Using computational fluid dynamics the impact of a particular perfusion technique can be simulated preoperatively. The aim of our study was to examine changes of the blood flow characteristics when perfusing the aorta with different techniques.

In der kardiovaskulären Medizin und insbesondere im Rahmen der invasiven Behandlung der koronaren Herzkrankheit stellt die intraaortale Ballongegenpulsation (IABP) ein vielfach bewährtes Verfahren dar, welches auch heute im Zeitalter der mechanischen Herz-Kreislauf-Unterstützung noch immer eine wichtige Rolle im klinischen Alltag spielt. Sie kommt hierbei sowohl periinterventionell im Herzkatheterlabor als auch perioperativ im Rahmen einer chirurgischen Revaskularisation zunehmend zum Einsatz. Die Ballonpumpe unterstützt invasiv die Hämodynamik des Patienten durch eine Steigerung von diastolischer Perfusion und diastolischem Blutdruck. Diese Mechanismen bewirken eine Verbesserung der Koronarperfusion während der Diastole und eine Reduzierung der Nachlast des Herzens. Die Wirksamkeit der IABP konnte in einer Vielzahl klinischer Situationen bewiesen werden. Als klassische Indikationen gelten: akutes Koronarsyndrom, sog. High-risk-Koronarinterventionen im Rahmen einer Herzkatheteruntersuchung, kardiogener Schock und der gesamte perioperative Bereich innerhalb der Herzchirurgie. Die möglichen Komplikationen der intraaortalen Gegenpulsation können durchaus schwerwiegend sein, obwohl sie in ihrer Inzidenz deutlich abgenommen haben. Bei sorgfältiger Patientenselektion und Implantationstechnik stellt die IABP eine effektive Therapieoption in der Behandlung von Patienten mit kardiovaskulären Erkrankungen dar. Die folgende Arbeit fasst die hämodynamischen Veränderungen, Indikationen, Komplikationen und Ergebnisse bei der Verwendung der IABP zusammen.

Article Ein Intrathorakales Herzunterstützungssystem (IVAD) zur Behandlung von myokardialem Pumpversagen was published on January 1, 1995 in the journal Biomedical Engineering / Biomedizinische Technik (volume 40, issue s1).