Alternative perfusion technique without axillary artery cannulation during combined aortic root and total arch replacement.

This report describes an effective cerebral perfusion method using an additional 4th side limb graft sewn to a trifurcated graft in patients undergoing redo aortic root reconstruction combined with total aortic arch replacement. This method is useful in cases where the origin of the innominate artery is unsuitable for clamping or when axillary perfusion is not employed, and assures continuous brain protection and minimizes circulatory arrest time.

Is there a role for surgery in the management of giant B-cell right atrial lymphoma?

We describe a case of a giant right atrial large B-cell lymphoma treated with initial surgical excision followed by postoperative chemotherapy. The patient had no clinical evidence of recurrence through 87 months after her hospital discharge. To our knowledge, this is the first reported case of long-term survival following this method of disease management. The discussion reviews the current status of chemotherapy for cardiac lymphomas and the pros and cons of treatment option algorithms.

Does cardioplegia type affect outcome and survival in patients with advanced left ventricular dysfunction? Results from the CABG Patch Trial.

BACKGROUND: There is controversy regarding which cardioplegic solution, temperature, and route of administration provides superior protection. The CABG Patch Trial enrolled a high-risk group of coronary artery disease patients with an ejection fraction of <36%. Thus, they constitute an ideal group to benefit most from optimal cardioplegic protection. METHODS AND RESULTS: All patients randomized into the trial were compared with respect to the use of blood and crystalloid cardioplegia. In addition, a questionnaire was sent to surgeons requesting blood cardioplegic temperature and route. Patients receiving crystalloid cardioplegia versus those receiving blood cardioplegia were found to have significantly more operative deaths (2% versus 0.3%, P:=0.02), postoperative myocardial infarctions (10% versus 2%, P:<0.001), shock (13% versus 7%, P:=0. 013), and postoperative conduction defects (21.6% versus 12.4%, P:=0. 001). Despite this, early death (6% crystalloid versus 4% blood cardioplegia) and late death (24% crystalloid versus 21% blood cardioplegia) statistics were not significantly different. Patients receiving normothermic blood had less postoperative right ventricular dysfunction (10%) than did patients receiving cold blood (25%) or cold blood with warm reperfusion (30%) (P:=0.004). There was no significant difference in early or late death. Finally, patients who received combined antegrade and retrograde cardioplegia had significantly less inotrope use (71% versus 84%, P:=0.002), right ventricular dysfunction (23% versus 41%, P:=0.001), and postoperative balloon pump use (12% versus 19%, P:=0.02) than did those who received antegrade cardioplegia. There was no difference in survival. CONCLUSIONS: Blood cardioplegia and combined antegrade and retrograde cardioplegia are superior to crystalloid and antegrade cardioplegia alone for postoperative morbidity. Despite this, there is no significant difference in early or late survival.

Myocardial protection by preconditioning of heart with losartan, an angiotensin II type 1-receptor blocker: implication of bradykinin-dependent and bradykinin-independent mechanisms.

BACKGROUND: Ischemic preconditioning (PC) represents a state-of-the-art technique for myocardial preservation. Although certain intracellular mediators have been shown to play a role in PC, the exact nature of the trigger for PC is not known. Our previous study demonstrated that intracellular bradykinin released from the heart during ischemia/reperfusion plays a role in myocardial preservation. This study was undertaken to further examine the mechanism of bradykinin-mediated PC. METHODS AND RESULTS: Since the bradykinin B(2) receptor is likely to provide cardioprotection by blocking angiotensin II formation, we determined the effects of an angiotensin II type 1 (AT(1)) receptor blocker, losartan, and a bradykinin B(2) receptor blocker, HOE 140, on myocardial protection. Isolated rat hearts were perfused initially by the Langendorff mode with Krebs-Henseleit buffer (KHB) for 15 minutes in the absence (control) or presence of losartan (4.5 micromol/L) and/or HOE 140 (10 micromol/L). After conversion to the working mode for 10 minutes (baseline), randomly assigned control and experimental hearts were subjected to 30 minutes of normothermic global ischemia followed by 2 hours of reperfusion. Myocardial function, infarct size, cardiomyocyte apoptosis, and amount of bradykinin/angiotensin released from the hearts were measured at baseline and during reperfusion while in the working mode. Significant postischemic ventricular recovery was demonstrated by improved developed pressure and aortic flow and reduced myocardial infarct size and apoptotic cell death with losartan, whereas the reverse was true for HOE 140. The functional recovery and infarct size-lowering ability of losartan were partially blocked and the antiapoptotic function of losartan was completely blocked by HOE 140. CONCLUSIONS: The results document that losartan reduced whereas HOE 140 increased myocardial ischemia/reperfusion injury by blocking AT(1) and bradykinin B(2) receptors, respectively, suggesting a role of the bradykinin B(2) receptor in PC. Losartan provided cardioprotection through both bradykinin-dependent and bradykinin-independent mechanisms.

Influence of the preoperative signal-averaged electrocardiogram on left ventricular function after coronary artery bypass graft surgery in patients with left ventricular dysfunction. The CABG Patch Trial.

Patients with ischemic left ventricular (LV) dysfunction often have an improved survival and life quality after coronary artery bypass grafting (CABG), in part due to an improvement in LV function. A lack of LV ejection fraction (EF) improvement postoperatively portends a worse prognosis. Recently, an abnormal preoperative signal-averaged electrocardiogram (SAECG) in patients with a severely depressed LV ejection fraction undergoing elective CABG was shown to be associated with a higher early and late postoperative mortality. The present study evaluated patients with severe LV dysfunction to identify any relation between an abnormal preoperative SAECG and postoperative changes in LV function after successful CABG. Forty-five patients with LV dysfunction (LVEF <0.36) scheduled for elective CABG underwent preoperative SAECG and both pre- and postoperative LVEF determinations using radionuclide scans. Thirty-one patients in the group had an abnormal preoperative SAECG and 14 patients had a normal preoperative SAECG. Baseline patient characteristics were similar in both groups and the mean preoperative LVEF was 0.26. Overall, LVEF improved 31% postoperatively with a significantly greater benefit noted in the group with a normal baseline SAECG (14.9+/-5.7-point vs 4.8+/-8.5-point increase, p <0.001). All patients whose LVEF did not improve or worsened postoperatively had an abnormal preoperative SAECG. No SAECG measure was altered significantly by the operation. A preoperative SAECG provides information on the postoperative functional recovery of ischemic myocardium.

Reduction of infarct size by systemic amino acid supplementation during reperfusion.

The amino acids aspartate and glutamate, in combination, were evaluated as a means of reducing infarct size and improving cardiac function during reperfusion in an intact pig having an acute anteroseptal infarct. Three groups of 6 pigs each were randomly studied in a blinded manner: control (no amino acids), aspartate/glutamate 3 mmol/L, and aspartate/glutamate 13 mmol/L. The left anterior descending coronary artery was occluded distal to its first diagonal branch for 60 minutes followed by reperfusion for 6 hours. Aspartate and glutamate were administered systemically immediately before reperfusion. The following parameters were measured: infarct size and percent area at risk, global metabolic function, global and regional myocardial function, and tissue parameters of metabolic function. The results clearly showed a significant decrease in infarct size from 60% of the area at risk in control pigs to 37% in both 3 mmol/L and 13 mmol/L amino acid groups. Cardiac output, coronary blood flow, and global oxygen consumption were not significantly affected by the use of amino acids relative to the control group. Global left ventricular mechanical function was also not adversely affected by the infarct and was not altered by amino acid administration. Regional function, however, was significantly decreased by occlusion of the left anterior descending coronary artery in all groups to near 20% and only significantly recovered to 64% in the 13 mmol/L amino acid group. Adenosine triphosphate and acetyl coenzyme A measurements documented significant increases in the 13 mmol/L amino acid group relative to the control group. The conclusions of this study strongly support aspartate/glutamate supplementation for stunned, reperfused myocardium. It is apparent that the effect of amino acid supplementation on glycolysis is directly translated into improved regional function and reduced infarct size.

Constitutive nitric oxide release is impaired after ischemia and reperfusion.

Myocardial ischemia and reperfusion may result in endothelial dysfunction and reduced release of nitric oxide. With the use of an amperometric sensor, the first direct measurements of constitutive nitric oxide release from a beating heart were measured from the coronary effluent of isolated working rat hearts subjected to ischemia and reperfusion. Rats, six to eight per group, were randomly studied as follows: control (no pretreatment) and pretreatment with the nitric oxide donor L-arginine (3 mmol/L), its enantiomer D-arginine (3 mmol/L), nitric oxide inhibitor N omega-nitro-L-arginine methyl ester (100 mumol/L), and combined N omega-nitro-L-arginine methyl ester/L-arginine. Isolated hearts were pretreated for 10 minutes before 30 minutes of global ischemia and 30 minutes of reperfusion. A nonischemic control group (n = 4) was continuously perfused with oxygenated unsupplemented buffer. After ischemia/reperfusion, hearts supplemented with L-arginine recovered significantly (p < 0.05) increased developed pressure, first derivative of the aortic pressure (dP/dtmax), and aortic flow compared with all other hearts that underwent ischemia/reperfusion. In addition, nitric oxide release was significantly (p < 0.05) increased during reperfusion in the L-arginine group. During reperfusion, the recovery of aortic flow correlated with nitric oxide release (r = 0.81, p < 0.0001). We conclude that after ischemia/reperfusion, endothelial dysfunction results in decreased nitric oxide release, which can be ameliorated with L-arginine pretreatment. The direct cytoprotective properties of nitric oxide may contribute to improved functional recovery in hearts pretreated with L-arginine. Augmentation of the L-arginine/nitric oxide pathway may provide a new approach for improved recovery after cardiovascular operations.

What is the best perfusion temperature for coronary revascularization?

BACKGROUND: [corrected] A National Institutes of Health-funded clinical trial of patients undergoing coronary artery bypass randomized perfusate and myocardial preservation to cold, tepid, or warm temperatures. The goal of the trial was to evaluate neurologic function before and after operation (4 days and 1 month after operation) and to measure hematologic data for fibrinolytic potential. METHODS: The three groups comprised 116 patients who completed neurologic evaluation by means of the Mathew scale out of 130 entered into the trial (37 cold group, 50 tepid, and 43 warm). Twenty-five patients had complete hematologic studies done. All three groups were comparable before operation. The myocardial preservation protocol used blood cardioplegic solution at cold (8 degrees to 10 degrees C), tepid (32 degrees C), or warm (37 degrees C) temperature and the systemic perfusate temperature during cardiopulmonary bypass was 20 degrees (cold), 32 degrees C (tepid), or 37 degrees (warm). RESULTS: Patients in the cold group had a longer duration of intubation and postoperative hospitalization and a slightly but significantly higher peak postoperative creatine kinase MB level than patients in the warm group. There were no deaths. There was deterioration in Mathew scale findings in all three groups, and no distinction could be made between groups. However, a significantly higher number in the cold group had an abnormal postoperative neurologic examination result that prompted computed tomographic scanning (18.9% cold, 2% tepid, 9.3% warm). A cerebrovascular accident was documented by computed tomographic scanning in 8.1%, 0%, and 4.7% of patients in the cold, tepid, and warm groups, respectively (not significant). Hematologic data documented significantly increased fibrinolytic potential in the warm group. CONCLUSIONS: Perfusion temperature is a factor in recovery from cardiopulmonary bypass. Cold has more adverse neurologic sequelae that prompt computed tomographic scanning whereas warm has more activation of fibrinolytic potential. Tepid is the best temperature for optimizing recovery from cardiopulmonary bypass.

Is there a relationship between systemic perfusion temperature during coronary artery bypass grafting and extent of intraoperative ischemic central nervous system injury?

OBJECTIVE: This study was designed to compare the volume of cerebral infarction in patients operated on under either hypothermic or tepid/normothermic perfusion for coronary revascularization. METHODS: A randomized trial with preoperative, postoperative, and late neurologic evaluation was conducted in patients undergoing coronary revascularization having either hypothermic or tepid/normothermic perfusion for coronary revascularization. The goal was to determine whether perfusion temperature correlated with neurologic dysfunction associated with coronary artery bypass. RESULTS: Twelve intraoperative ischemic strokes occurred during coronary revascularization in a series of 291 patients. Six of these were in the group receiving hypothermic perfusion and 6 in groups receiving the tepid/normothermic perfusion. Measuring the infarct volume documented that 3 of the strokes in each group resulted in minor or small infarcts and 3 in each group were significant, major strokes. The volume of infarction, whether including all 6 patients in each group or only those with major strokes, was no different between the hypothermic and the tepid/normothermic groups. CONCLUSIONS: In this series of 291 patients randomized to perfusion temperature, we observed no relationship between the size of a cerebral ischemic infarct and the perfusate temperature during coronary revascularization.

Cardiac retractor for coronary bypass operations.

The Thompson retractor, used mainly for abdominal procedures, has been used to retract the heart and facilitate exposure for the performance of inferior wall or posterolateral wall coronary anastomoses. It has been found to be very effective and can replace a second assistant to retract the heart or avoid other cumbersome methods of cardiac retraction.

Tranexamic acid significantly reduces blood loss associated with coronary revascularization.

Four hundred fifteen patients undergoing coronary revascularization over a 12-month period were divided into two groups: 209 controls in the first 6 months received no tranexamic acid (TA) before cardiopulmonary bypass and 206 patients in the second 6 months received TA as a hemostatic agent. The demographics and the surgical techniques used were similar in the two groups. With TA there was a significant decrease in blood loss postoperatively, from 1,114.1 mL in the controls to 803.7 mL in those given TA (p < 0.001); in red blood cell use, from 1.7 units/patient in the controls to 0.69 units/patient in those given TA (p < 0.001); in fresh frozen plasma requirements, from 0.23 units/patient in the controls to 0.024 units/patient in those given TA (p < 0.01); and in platelet transfusion, from 1.06 units/patient in the controls to 0.30 units/patients in those given TA (p < 0.01). The percentages of patients not receiving any blood products were 65% in those given TA versus 49% in the controls (p < 0.01). There was no significant difference between the two groups in the incidence of perioperative myocardial infarction, cerebrovascular accidents, pulmonary embolism, or venous thrombosis to clearly suggest hypercoagulability. In this study, TA profoundly affected the coagulopathy associated with bypass in patients undergoing coronary revascularization. It significantly reduced blood loss and blood product transfusions. Any potential increased thrombotic complications could not be clearly demonstrated in this study, but should not be ignored.

A cost-effective retractor and heart stabilizer for minimal-access coronary bypass.

Exposure for internal mammary artery harvesting and immobilization of the coronary artery during the performance of minimally invasive direct coronary artery bypass grafting requires the use of appropriate retractors and instruments. We have successfully used existing retractors and instruments, modified for such use, which are reusable and cost effective. The use of such a retractor and cardiac stabilizer is described.

Fenestrated felt facilitates anastomotic stability and safety in "off-pump" coronary bypass.

Metal stabilizing devices used in beating heart surgery, although largely effective, occasionally slip or cause lacerations of epicardial veins or myocardium, resulting in blood loss that requires time-consuming corrective maneuvers. The use of a fenestrated felt as a cushion in conjunction with the stabilizers eliminates slipping and/or trauma, thus facilitating coronary anastomoses on the beating heart.

Risk of dysphagia after transesophageal echocardiography during cardiac operations.

BACKGROUND: Dysphagia can be a significant complication following cardiac operations. This study evaluates its incidence and relationship to intraoperative transesophageal echocardiography (TEE) for specific indications versus known factors such as stroke or prolonged intubation. METHODS: Records of 838 consecutive cardiac surgical patients were reviewed, and categorized into those who received TEE for specific indications versus those who did not (nonTEE). Dysphagia was recorded when symptoms were confirmed by barium cineradiography. Multiple logistic regression identified significant factors causing dysphagia. RESULTS: TEE was significantly related to the development of postoperative dysphagia by multiple logistic regression (p < 0.001). After controlling for other significant factors (stroke, left ventricular ejection fraction, intubation time, duration of operation), the odds of dysphagia for TEE patients was 7.8 times greater than for nonTEE patients. CONCLUSIONS: TEE may be an independent risk factor for dysphagia following cardiac operations.

Influence of steroids on complement and cytokine generation after cardiopulmonary bypass.

BACKGROUND: It is recognized that the inflammatory mediators complement and cytokines are generated during cardiopulmonary bypass as an endogenous response to extracorporeal circulation. METHODS: Nineteen randomized patients (10 steroid/9 nonsteroid) entered an institutional review board-approved protocol to measure complement and interleukin level generation before and after elective coronary revascularization. The steroid regimen involved 1 g of methylprednisolone sodium succinate intravenously before bypass and 4 mg of dexamethasone every 6 hours for four doses during the first 24 hours of recovery. Complement and interleukin levels were measured before bypass, immediately after bypass, and at 24, 48 and 72 hours of recovery. RESULTS: In the nonsteroid group, there was a significant elevation in all inflammatory mediators relative to the steroid group. The predominant changes occurred at 24 hours after operation. CONCLUSIONS: Steroids produced a dramatic reduction in complement and interleukin levels. The number of patients was clearly too small to document a clinical consequence of steroid administration.

L-arginine reduces endothelial inflammation and myocardial stunning during ischemia/reperfusion.

BACKGROUND: This study evaluated whether the nitric oxide precursor L-arginine could reduce ischemia/reperfusion injury by preventing leukocyte-endothelial interactions. METHODS: Normothermic regional ischemia was induced in the open-chest working pig heart for 30 minutes followed by 90 minutes of reperfusion. A preischemic 10-minute intravenous infusion of 4 mg.kg-1.min-1 of L-arginine (n = 12) was compared with 12 control pigs. Nitric oxide release was measured from the coronary sinus using an amperometric probe. Left ventricular function, malonaldehyde, creatine kinase, myocardial oxygen extraction, and the soluble adhesion molecules (intracellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, and vascular cell adhesion molecule-1) were measured. RESULTS: Nitric oxide release was significantly reduced from baseline throughout ischemia/reperfusion only in the control group. Systolic and diastolic function, and myocardial oxygen extraction were also significantly decreased during early reperfusion in the control compared with the L-arginine group. Peak creatine kinase release was not significantly different between groups. The incidence of ventricular fibrillation, malonaldehyde release, and soluble intracellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, and vascular cell adhesion molecule-1 were each significantly decreased during reperfusion in the L-arginine group. CONCLUSIONS: L-Arginine reduced lipid peroxidation, plasma levels of soluble adhesion molecules, myocardial stunning, and arrhythmias. These results support an excessive endothelial injury/inflammatory response after regional ischemia/reperfusion that can be ameliorated through augmented nitric oxide.

Hypoxic preconditioning enhances functional recovery after prolonged cardioplegic arrest.

The purpose of this study was to assess the ability of hypoxic preconditioning to improve myocardial salvage after prolonged hypothermic cardioplegic arrest. Isolated working rat hearts were arrested at 4 degrees C with St. Thomas' Hospital cardioplegic solution and immersion stored for 4 or 6 hours. Two groups were studied, control and hypoxically preconditioned (HP) hearts. After 4 hours' preservation, aortic flow, coronary flow, and the first derivative of aortic pressure were 8.7 +/- 1.6 mL/min, 17.8 +/- 1.6 mL/min, and 2,064 +/- 123 mm Hg/s, respectively, in control hearts (n = 11) and 25.7 +/- 2.5 mL/min, 27.1 +/- 2.5 mL/min, and 2,655 +/- 93 mm Hg/s, respectively, in HP hearts (n = 11) (p < 0.05). After 6 hours' preservation, aortic flow, coronary flow, and the first derivative of aortic pressure were 3.5 +/- 1.2 mL/min, 18.8 +/- 0.4 mL/min, and 1,622 +/- 226 mm Hg/s, respectively, in control hearts (n = 6) and 21.5 +/- 3.2 mL/min, 25.5 +/- 2.3 mL/min, and 2,439 +/- 239 mm Hg/s, respectively, in HP hearts (n = 6) (p < 0.05). After 6 hours' preservation, adenine nucleotides and creatine phosphate levels were not significantly different between the two groups, but lactate dehydrogenase release was significantly increased (p < 0.05) in control versus HP hearts (4.66 +/- 0.58 IU/L versus 1.98 +/- 0.28 IU/L). We conclude that hypoxic preconditioning reduces cellular necrosis and preserves myocardial function after prolonged hypothermic cardioplegic arrest.

Does warm blood retrograde cardioplegia preserve right ventricular function?

BACKGROUND: Efficacy of warm blood retrograde cardioplegia in preserving right heart function remains controversial. The current study was conducted to gauge the preservation of right ventricular function after warm blood retrograde cardioplegia. METHODS: We studied 75 consecutive patients undergoing isolated heart valve procedures with warm blood retrograde cardioplegia as the exclusive mode of preservation. Right ventricular radionuclide ejection fraction and hemodynamic measurements using a pulmonary artery catheter were calculated before and within 3 days after operation. RESULTS: Postoperative radionuclide right ventricular ejection fraction was well preserved at 0.4686 +/- 0.0122 compared with 0.4327 +/- 0.0255 preoperatively (p = 0.7064). Right ventricular systolic work index improved from 5.82 +/- 0.52 to 8.97 +/- 0.60 g x m/m2 (p < 0.0001) and cardiac index increased from 2.40 +/- 0.09 to 2.92 +/- 0.11 L/m2 (p < 0.0001). When right ventricular systolic work index was correlated with preload, 30 patients moved up and down on the same ventricular function curve and 42 moved to a higher inotropic curve postoperatively. Only 3 patients demonstrated decreased inotropy. CONCLUSIONS: In the clinical setting warm blood retrograde cardioplegia used as the exclusive mode of myocardial preservation provides adequate protection of the right heart.

Echocardiography allows safer venous cannulation during excision of large right atrial masses.

BACKGROUND: Excision of large right atrial masses requires bicaval cannulation and cardiopulmonary bypass. Safe venous cannulation can be accomplished only by knowing the exact intracavitary location and extension of the mass to avoid fragmentation. Transthoracic echocardiography and intraoperative transesophageal echocardiography, although helpful, cannot always define the exact intracavitary relationships of the tumor. METHODS: We have used both intraoperative transesophageal and epicardial echocardiography to guide venous cannulation in 4 patients with large right atrial masses. Both echo images are used by the surgeon to select the exact site and method of cannulation to avoid fragmentation of the mass. Epicardial echocardiography complemented the images obtained by transesophageal echocardiography. RESULTS: The technique of combined transesophageal and epicardial echocardiography allowed safe venous cannulation in all 4 patients. Each of the right atrial masses was safely excised using case-specific cannulation techniques guided by the echocardiographic images. CONCLUSIONS: We propose the routine use of both intraoperative transesophageal and epicardial echocardiography in guiding venous cannulation for safe excision of large right atrial masses.

Influence of cardiopulmonary bypass perfusion temperature on neurologic and hematologic function after coronary artery bypass grafting.

BACKGROUND AND METHODS: A National Institutes of Health-sponsored trial (1994 to 1998) randomized patients undergoing coronary artery bypass grafting that required three or more grafts to receive perfusion at either cold (20 degrees C), tepid (32 degrees C), or warm (37 degrees C) temperature. The goal of the study was to evaluate morbidity, primarily neurologic dysfunction and secondarily hematologic factors. One thousand seven hundred seventy-seven patients were screened and 291 enrolled. Neurologic function was studied by a dedicated pool of blinded neurologists. A standard test battery termed the Mathew Scale using three subscales--cognitive function, elemental skills, and disability--was used to study central nervous system function. Hematologic function was assessed in 53 of the 291 patients with measurements of postoperative fibrinolytic potential. RESULTS: All preoperative and operative data were comparable between groups. A decrease in Mathew Scale was seen in 69% of patient from before operation to immediately after operation. However, between the early postoperative study and the 1-month follow-up, 48% of patients had returned to baseline. There was no difference noted across temperature groups in any neurologic parameter of function. In all, 55% of the group were at or above their preoperative level at 1 month. Forty-nine patients suspect for cerebrovascular accident had a computed tomographic scan, but only 13 (4.5%) had a documented cerebrovascular accident (4 patients in the warm, 3 in the tepid, and 6 patients in the cold group). Fibrinolytic changes correlated with perfusion temperature documented that fibrinolysis was most active at 37 degrees C. Thus, increasing perfusate temperature increases fibrinolysis, which was associated with reoperation for bleeding in 4% warm group patients, 1% tepid, and 0% cold group patients (0.1 > p > 0.05). No other perioperative complications were temperature related. There were 4 deaths (1.4%) (1 in the warm group, 2 in the tepid group, and 1 in the cold group). CONCLUSIONS: (1) Persistent postoperative neurologic dysfunction at 1 month occurs in 36% of patients undergoing coronary artery bypass grafting and is not related to a cerebrovascular accident; 2) perfusion temperature has no relationship to neurologic function after bypass; and 3) fibrinolytic activity is greatest at warm temperatures.