Lothar Eckel

Differences in the recovery of platelet counts after biological aortic valve replacement

Observations among Karlsburg patients in 2006 revealed that the majority of very low platelet levels inducing postoperative heparin-induced-thrombocytopenia (HIT)-diagnostics with at the end negative results appeared related to aortic valve replacement (AVR) with stentless bioprostheses. We compared the postoperative courses of platelet counts in patients having had AVR with stentless prostheses (Sorin Biomedica Freedom Solo [SOLO]) or stented prostheses (Carpentier Edwards Perimount [PM]). Between February 2005 and April 2007, 209 patients received AVR with SOLO, in 137 patients a PM-prosthesis was implanted. The mean platelet levels were compared from the first up to the fifth postoperative day. A higher occurrence of platelet levels below 100 Gpt/l between the second and the fifth postoperative day was found in the SOLO-group (71.9%) compared with the other biological substitute PM (36.6%). Differences in platelet counts between SOLO- and PM-subgroups were measured for day 2 (P=0.03), day 3 (P=0.0004) day 4 (P=0.0007), day 5 (P=0.0002) and at discharge (P<0.0001). Following intervention with conventional biological AVR, differences in the postoperative recovery of platelet counts can be detected, depending on the prosthesis used. The causes for and the clinical implications of this phenomenon are not yet assessed.

Left main coronary artery stenosis after aortic valve replacement: genetic disposition for accelerated arteriosclerosis after injury of the intact human coronary artery?

Background:Left main coronary artery stenosis is a rare but life-threatening complication after aortic valve replacement because of coronary perfusion-related trauma to the vessel wall with cannulation of the coronary ostia. We investigated whether this complication still occurs in the 1990s despite the use of more advanced catheter materials and modern surgical preservation techniques. MethodsFour years after identification of the first two cases in 1987, five further patients had developed left main coronary artery stenosis after aortic valve replacement (incidence, 0.9%) at the cardiothroacic clinic of the J.W Goethe University and were studied for contributing factors. Results:Severe coronary ostial stenosis developed within 1 to 6 months after aortic valve replacement. In one such case, intimal proliferation was seen in a biopsy specimen that was comparable to the restenosis induced by coronary angioplasty. The clinical characteristics of the patients developing the complication, the surgical technique, and the intraoperative course did not differ from the other patients. However, five of the seven patients (71 %) had a common genetic trait concerning their apolipoprotein E genotype (the e4 allele) that is normally present in only 10% to 15% of patients screened (P<0.01). Conclusions:These lesions seem to result from a uniform response of the vessel wall to injury. Their incidence is probably related in part to the degree of injury after trauma to the coronary ostia during cannulation for myocardial protection. Patients with the

Controlled limb reperfusion in patients having cardiac operations

4 allele might be genetically predisposed for a pathologically increased response of proliferative repair mechanisms after arterial injury. The complication can be avoided by not instrumenting the coronary ostia for direct antegrade cardioplegia but using retrograde delivery as an alternative method of myocardial protection.

Electrophysiological study of human ventricular heart muscle treated with quinidine: interaction with isoprenaline.

Patients requiring urgent surgical revascularization due to unstable coronary artery disease are usually pretreated with multiple antithrombotic drugs. The perioperative risks of this type of treatment were investigated in 123 patients who underwent emergency coronary artery bypass grafting (CABG) at our institution.Eighty-two patients (group A) received heparin and acetylsalicylic acid solely and 41 patients (group B) received additionally ADP-receptor antagonists (82.9%), glycoprotein IIb/IIIa inhibitors (12.2%) or thrombolysis (14.6%) preoperatively. Both groups were similar regarding demographic data and overall clinical status. Preoperative coagulation parameters and intraoperative characteristics were comparable. Blood loss via chest tubes was not significantly different between groups. Transfusion of red blood cells and fresh frozen plasma were slightly, but not significantly increased in group B. Transfusion of pooled platelets was low in general and similar in both groups. Re-exploration rate, medium intensive care unit and hospital stay as well as perioperative mortality were comparable.Excessive antithrombotic pretreatment seems to bear no additional risk in emergency CABG and may be beneficial in this setting.

Stunned myocardium after off-pump coronary artery bypass grafting

HYPOTHESIS Severe limb ischemia in patients having cardiac operations may occur after intraaortic balloon pump insertion, prolonged femoral vessel cannulation, percutaneous cardiopulmonary bypass, dissecting aneurysms, or emboli. Normal blood reperfusion can cause a postischemic syndrome that increases morbidity and mortality. This clinical study is based on an experimental infrastructure patterned after controlled cardiac reperfusion. (1) It tests the hypothesis that controlled limb reperfusion (i.e., modifying the composition of the initial reperfusate and the conditions of reperfusion) reduces the local and systemic complications seen after normal blood reperfusion. (2) It reports initial clinical application of this strategy in three cardiac surgery centers. METHODS Controlled limb reperfusion was applied to 19 patients with signs of severe prolonged unilateral or bilateral ischemia (including paralysis, anesthesia, and muscle contracture); six patients (32%) were in cardiogenic shock. The mean ischemic duration was 26 +/- 6 hours. The reperfusion method includes a 30-minute infusion into the distal vessels of a normothermic reperfusate solution mixed with the patients arterial blood (obtained proximal to the obstruction) in a 6:1 blood/reperfusate ratio. Data are mean +/- standard error of the mean. RESULTS Sixteen patients (84%) survived with salvaged and functional limbs at the time of discharge. No renal, cardiac, pulmonary, cerebral, or hemodynamic complications developed in the survivors. The three deaths occurred in patients undergoing controlled limb reperfusion while in profound postoperative cardiogenic shock; neither postischemic edema nor contracture developed in any of them. CONCLUSIONS These findings show that controlled limb reperfusion can be applied readily with standard equipment that is used for cardiac surgery and may salvage limbs while reducing postreperfusion morbidity and mortality.

New Surgical Treatment for Severe Limb Ischemia

We have investigated the effects of quinidine on the force of contraction and the intracellularly recorded action potential in papillary muscles isolated from human hearts. All preparations were obtained from patients undergoing corrective open heart surgery. The following results were obtained: (1) quinidine had a depressant effect on myocardial contractile force; (2) quinidine reduced the maximal upstroke velocity of the action potential; (3) quinidine shortened the plateau phase and prolonged the terminal repolarization of the action potential; (4) at higher concentrations quinidine reduced the resting potential; and (5) the depression by quinidine of both the plateau and the force of contraction was antagonized by isoprenaline. It is concluded that quinidine reduces the membrane conductances for sodium, calcium, and potassium ions. All of these actions of quinidine may contribute to the antiarrhythmic effects of the drug. The negative inotropic effect of quinidine can be explained by a depression of the calcium conductance at the myocardial cell membrane. The results show that earlier findings in laboratory animals regarding the effects of quinidine on the upstroke velocity and repolarization phase of the action potential are applicable to the human heart.

Sarcoma associated with silver coated mechanical heart valve prosthesis

Off-pump coronary artery bypass grafting is increasingly performed. Because these procedures are associated with temporary myocardial ischemia, there is a risk of ischemia-related complications. We report two cases of myocardial stunning after off-pump coronary artery bypass grafting using the Octopus tissue stabilizer. On the basis of our experiences, means to prevent stunning are discussed.

Submitral left ventricular tuberculoma.

Revascularization after prolonged complete limb ischemia may result in severe damage to skeletal muscle and systemic alterations (postischemic syndrome). Our previous experimental studies have shown that this injury can be reduced substantially by treating the jeopardized extremity by controlling the conditions of reperfusion and composition of the initial reperfusate. In the present study this concept of controlled limb reperfusion was applied in patients with prolonged severe limb ischemia. Controlled limb reperfusion was used in 14 patients after prolonged complete uni- or bilateral ischemia. The ischemic interval ranged from 5 to 21 h. Two patients were in cardiogenic shock, 11 had associated cardiac disease, and seven coexistent peripheral vascular disease. After systemic heparinization, standard thromboembolectomy was done using a Fogarty catheter. Cannulas were placed into the iliac, profunda, and superficial femoral arteries and were connected to a reperfusion set. Oxygenated blood was drawn from the iliac artery and mixed with an asanguineous solution (ratio 6:1). This controlled reperfusate was delivered into the profunda and superficial femoral arteries using a single rollerpump. The system allows control of the composition of the reperfusate (calcium, pH, osmolarity, glucose, substrate, pO2, free radical scavengers) and the conditions of reperfusion (pressure, flow, temperature). After 30 min of controlled limb reperfusion, the cannulas were removed and normal blood reperfusion started. All 12 patients who were stable hemodynamically before the operation survived the revascularization. Eleven patients, including one with acute aortic occlusion for several hours, were discharged with functional recovery of their extremities. Despite the severe ischemic insult, controlled limb reperfusion avoided amputation and profound systemic complications. Two patients who were in cardiogenic shock preoperatively died from progressive cardiac failure. We conclude that controlled arterioarterial limb reperfusion may reduce the local manifestations of the postischemic syndrome after prolonged periods of ischemia, may salvage limbs thought previously to be damaged irreversibly by prolonged ischemia, and can be done easily in the operating room.

Myocardial rewarming mirrors intraoperative mammary artery graft function.

Sarcomas can develop in association with foreign material (eg, from Dacron vascular prostheses). We report on a left atrial rhabdomyosarcoma that developed within 1 year of mitral valve replacement by a Silzone-coated St. Jude Medical mechanical heart valve. Tumor resection and redo valve replacement were done. Six months later the patient was alive, but an echocardiogram showed tumor recurrence. Although this is a single case, an association between heart valve prostheses and malignant tumors should be considered.