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ABSTRACT: The scope of this paper was to determine whether ischemic and reperfusion damage in cardiac surgery can be detected by measurement of electrical bioimpedance (EBI). Conventional pacing wires were replaced by pacing wires with sputtered iridium coating in order to reduce polarization associated with two-electrode impedance measurements. A custom-built bioimpedance analyzer (Osypka Medical GmbH, Berlin, Germany) measured the real part of impedance Re(Z) and the phase (ϕ) at three frequencies (1, 10, and 1000 kHz) and determined an extracellular space index (EZRI) as the quotient of Re(Z) at 1000 kHz and Re(Z) at 1 kHz. Our study included six patients (conventional coronary artery bypass graft, age 68.1 ± 8.3 years) subject to routine cardioplegic ischemia and reperfusion. Preischemic bioimpedance measurements were not impaired by interference of the beating heart. Intraischemically, bioimpedance at 1 kHz and phase at 10 kHz increased until opening of a bypass graft, which is probably induced by closure of gap junctions and cell swelling processes. After cross clamping, EZRI slowly decreased as an effect of mild cell swelling. After ischemia, values returned almost to baseline measurements, indicating sufficient reperfusion processes. Measurement of EBI correlates with myocardial ischemic injury and is applicable in a two-electrode setup providing low-polarization pacing wires.
IEEE transactions on bio-medical engineering 06/2011; 58(6):1511-8. · 2.15 Impact Factor
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ABSTRACT: On-pump cardiac surgery is accompanied by complex alterations of hemostasis. The excessive postoperative bleeding has been attributed to acquired platelet dysfunction, impaired plasmatic coagulation, and increased fibrinolysis. The characterization of the hemostatic defects responsible for bleeding is crucial for specific treatment and optimal clinical management of the patient. For rapid determination of platelet-dependent primary hemostatic capacity (PHC), the Platelet Function Analyzer PFA-100 system is available. To evaluate the PFA performance in perioperative monitoring, a study was performed in 49 patients selected for low bleeding risk undergoing selective primary coronary artery bypass grafting (CABG). We compared PHC with Simplate bleeding time (BT) and platelet aggregometry. Furthermore, we analyzed global hemostasis by thromboelastography (TEG) and plasmatic coagulation by standard clotting tests prothrombin time (PT, Quick), activated partial thromboplastin time (aPTT), thrombin time (TT) and clotting factors and fibrinolysis by batroxobin (reptilase) time (RT). In all patients BT was postoperatively increased by 1.5- to 2-fold irrespective of perioperative complications and decreased to mildly prolonged values on the first postoperative day (1st day). In patients without complications, PHC in both collagen-adenosine diphosphate closure time (CADP-CT: 83 seconds preop, 78 seconds postop, and 74 seconds 1st day) and collagen-epinephrine closure time (CEPI-CT: 98 seconds preop, 95 seconds postop, 85 seconds 1st day) remained nearly stable. Apart from a patient with postoperative moderate thrombocytopenia, in bleeding patients no other significant defect of postoperative platelet hemostatic capacity was observed. However, on 1st day, the PHC of those patients was significantly reduced compared with non-bleeding patients. In patients with postoperative myocardial ischemia, increased PHC was identified by significantly shorter postoperative CADP-CT (66 seconds vs. 83 seconds) than in uncomplicated patients. By aggregometry, partial platelet dysfunction was observed in some patients without correlation to bleeding complications. In seven of 9 patients the postoperative bleeding complication was attributed to prolonged heparin anticoagulation and/or mildly enhanced fibrinogenolysis/fibrinolysis by TEG and standard plasmatic coagulation tests (TEG: k time 18 minutes vs. 8 minutes; aPTT: 47 seconds vs. 32 seconds; TT: 18.0 seconds vs. 12.3 seconds) and (RT: 19.5 seconds vs. 17.7 seconds). The impairment of PHC, platelet aggregation, and clotting factors observed on the 1st day in bleeding and in intra-aortic balloon pump (IABP) patients are most likely secondary effects, for example, loss of active platelets and clotting factors, to the primary postoperative bleeding or implantation of the IABP. In conclusion, our data indicate that in standard CABG procedures highly variable alterations of the hemostatic system occur after cardiopulmonary bypass (CPB) even in patients with assumed low operative risks. For identification of post-CPB bleeding complications, thromboelastography, aPTT, and TT and heparin and batroxobin (reptilase) time as fibrinolysis-sensitive assays are useful. Platelet function appears to be rapidly restored in uncomplicated CABG. PHC determination by PFA-100 demonstrates a high specificity for adequate platelet function and, therefore, could be beneficial in improved transfusion of platelet concentrates. PHC testing by PFA-100 may help identify postoperative platelet hyper-reactivity associated with myocardial lesion.
Seminars in Thrombosis and Hemostasis 02/2005; 31(4):426-40. · 4.22 Impact Factor
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ABSTRACT: Transcatheter occlusion of uncomplicated atrial septum defects (ASD) is recognized as an effective and minimally invasive method. Sometimes, serious early and late complications require surgical intervention. We therefore investigated reasons and outcomes of the secondary surgical approach.
5 patients (aged 5-73 yrs) were admitted to our institution for device explantation and surgical ASD closure. ASDOS devices (A devices) had to be explanted in 4 patients and a SIDERIS "buttoned" occluder (S device) had to be explanted in 1 patient. The period from transcatheter implantation to surgical explantation ranged from 1 hour to 3 years.
3 patients (60 %) had to be operated in an emergency setting. In our youngest patient (5 yrs), the A device separated and embolized into the aorta and pulmonary artery. A pregnant women who needed emergent cesarean section developed hemopericard and tamponade due to atrial perforation by a fractured leg of an A device. In another A device, a suspect endocarditis caused membrane perforation. Malpositioning of an S device was the reason for operation. All patients recovered well without neurological symptoms.
Transcatheter closure of uncomplicated ASD is a feasible alternative but surgical stand-by is essential. Nevertheless more complicated ASD should be operated, especially since the cosmetically satisfactory techniques of minimal invasive heart surgery are available.
The Thoracic and Cardiovascular Surgeon 01/2002; 49(6):338-42. · 0.93 Impact Factor