Immediate hemodynamic effects of thrombolytic therapy on the ischemic myocardium.

Thrombolytic agents are used to restore coronary artery perfusion and limit the size of a myocardial infarction. The systemic effects of these drugs, streptokinase (SK), urokinase (UK), and recombinant tissue plasminogen activator (rtPA), have been studied extensively. Although their effects on rheology and late myocardial performance have been well-documented to date, there have not been any studies evaluating the acute hemodynamic consequences of thrombolytics immediately after administration. In this report we use an isolated Langendorf rodent heart preparation to evaluate the acute hemodynamic effects of thrombolytic therapy on both the normal and the ischemic myocardium. We quantified performance by documenting cardiac output, coronary blood flow, and blood pressure. Although each thrombolytic agent significantly transiently impairs cardiac performance, differences in effect between the agents were statistically insignificant. This was also the case with both the normal as well as the ischemic myocardium. The results of this study would not support favoring the use of one of these agents over the other with regards to primary myocardial performance.

Modulation of alloreactivity in transplant recipients by phenotypic manipulation of donor endothelium.

Phenotypic manipulation of allograft endothelium to reduce immunogenicity would have a significant impact on transplantation. In this study we have demonstrated that random seeding of a heart allograft with endothelium, of host origin, not only promotes long-term survival, but reduces the requirement for pharmacologic immunosuppression. We propose that this simple technology could easily be extrapolated to the clinical arena where hypothermia and preservation solutions have allowed allografts to remain ex vivo for extended periods.

The haemostatic effectiveness of autologous platelet rich plasma sequestered after heparin administration and institution of cardiopulmonary bypass.

Preoperative harvesting and postoperative reinfusion of autologous platelet rich plasma (PRP) has been reported to decrease blood loss as well as the requirement for homologous blood transfusion following cardiopulmonary bypass (CPB). We have developed a technique of intraoperative PRP sequestration which occurs during the initial period of CPB after the patient's circulation is supported and heparin has been given (PRP+). This process does not require any additional hardware, personnel or expense and it is performed without difficulty or complication. To evaluate the effect of PRP+ sequestration and reinfusion on blood loss and homologous blood requirement after CPB, we randomly assigned 126 consecutive patients undergoing elective open heart surgery into the experimental group 1 (PRP+) (n = 64) or the control (no platelet pheresis) group 2 (n = 52). A third group (n = 10) were not included in the randomization. Patients in group 3 had PRP prepared by conventional techniques (PRPc) prior to heparin administration and given to the patient after protamine infusion. Aggregation and activation studies were performed on the PRP+, PRPc, and blood bank platelets (BBP). Per cent aggregation of PRP in response to ADP was superior to that of BBP. There were no significant differences in ADP induced aggregation between PRP+ and PEPc. There was no significant difference in platelet activation (CD62) or number between the three groups. Patients infused with PRP+ showed significantly increased aggregation to ADP when compared with untreated patients 120 minutes after return to the ICW. Furthermore, more homologous haemostatic components (platelets/fresh frozen plasma) were required in the control group. We have demonstrated that collection of autologous PRP+ after administration of heparin does not interfere with its haemostatic effectiveness compared with PRPc prepared before the initiation of bypass. Moreover, this can be performed universally in haemodynamically unstable patients without any additional costs.