***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND : Our aim was to investigate postoperative complications and mortality after administration of aprotinin compared to tranexamic acid in an unselected , consecutive cohort . METHODS : Perioperative data from consecutive cardiac surgery patients were prospect ively collected between September 2005 and June 2006 in a university-affiliated clinic ( n = 1188 ) . During the first 5 mo , 596 patients received aprotinin  ( Group A ) ; in the next 5 mo , 592 patients were treated with tranexamic acid ( Group T ) . Except for antifibrinolytic therapy , the anesthetic and surgical protocol s remained unchanged . RESULTS : The pre- and intraoperative variables were comparable between the treatment groups . Postoperatively , a significantly higher incidence of seizures was found in Group T ( 4.6 % vs 1.2 % , P < 0.001 ) . This difference was also significant in the primary valve surgery and the high risk surgery subgroups ( 7.9 % vs 1.2 % , P = 0.003 ; 7.3 % vs 2.4 % , P = 0.035 , respectively ) . Persistent atrial fibrillation ( 7.9 % vs 2.3 % , P = 0.020 ) and renal failure ( 9.7 % vs 1.7 % , P = 0.002 ) were also more common in Group T , in the primary valve surgery subgroup . On the contrary , among primary coronary artery bypass surgery patients , there were more acute myocardial infa rct ions and renal dysfunction in Group A ( 5.8 % vs 2.0 % , P = 0.027 ; 22.5 % vs 15.2 % , P = 0.036 , respectively ) . The 1-yr mortality was significantly higher after aprotinin treatment in the high risk surgery group ( 17.7 % vs 9.8 % , P = 0.034 ) . CONCLUSION : Both antifibrinolytic drugs bear the risk of adverse outcome depending on the type of cardiac surgery . Administration of aprotinin should be avoided in coronary artery bypass graft and high risk patients , whereas administration of tranexamic acid is not recommended in valve surgery Studies that compare the use of HTK vs. blood or crystalloid cardioplegia for myocardial protection in cardiac surgery , r and omized or non-r and omized , will be selected . Large case series of adult cardiac surgery with the use of HTK for myocardial protection but without a comparator , including more than 100 patients will be included in a separate analysis . Electronic search es will be performed of Medline , the Cochrane Data base of Systematic Review s , Pubmed and EMBASE . Manual search es of reference lists will be used to identify any studies not found in the initial search . Only studies in English will be included . Abstract s , letters , and review articles will be excluded . Differences of opinion between review ers will be discussed with a senior investigator . An in/out form will be prepared to assess studies for inclusion or exclusion using predetermined inclusion criteria . The inclusion of studies will be assessed by two independent review ers , with differences of opinion resolved by discussion with a senior investigator . A PRISMA flow-diagram will summarize inclusion /exclusion of studies . Level of evidence for each study will be reported to assess the quality of the evidence BACKGROUND Ischemia-reperfusion injury during open heart surgery related to unsuccessful myocardial protection may increase morbidity or mortality . We analyze the clinical outcome after cardiac surgery with a cardioplegic solution based on intracellular components added with histidine-ketoglutarate-tryptophan . METHODS Thirty patients programmed for elective open heart surgery were r and omized into two groups . In group I ( n = 15 ) , myocardial protection was carried out with Bretschenider solution ( HTK ) , and in group II ( n = 15 ) with conventional crystalloid cardioplegia . The incidence of arrhythmias , inotropic support requirement , and length-of-stay in the intensive care unit were evaluated . RESULTS During reperfusion , there was no difference in incidence of arrhythmias ; however , in the postoperative period group I had a lower incidence of arrhythmias ( p = 0.001 ) . Inotropic support ( p = 0.003 ) and length-of-stay in the intensive care unit ( p = 0.037 ) were lower in group I. There were no deaths in either group . CONCLUSIONS It was concluded that myocardial protection with Bretschneider solution effectively decreases incidence of arrhythmias , inotropic support , and length-of-stay in the intensive care unit The study compares the single dose histidine-tryptophan-ketoglutarate ( HTK ) cardioplegia to the repeatedly delivered St Thomas ' Hospital Solution ( STHS ) with respect to preservation of left ventricular mechanoenergetics and leakage of troponin T in a porcine experimental model . Fourteen pigs were r and omized to a single infusion of 30 ml/kg HTK cardioplegia ( n=7 ) or 500 ml STHS ( n=7 ) followed by 200 ml after 20 and 40 min . After 1 h of aortic cross-clamping on cardiopulmonary bypass ( CPB ) , the pigs were weaned and the hearts reperfused for 4 h. Stroke work ( SW ) was determined by a conductance catheter in the left ventricle . Myocardial oxygen consumption ( MvO(2 ) ) was measured as a function of coronary blood flow and arterial-to-coronary sinus oxygen saturation difference . Troponin T was sample d from the coronary sinus . The slope of the SW-MvO(2 ) relationship increased by 1.09 ( + /-0.53 ) in the HTK group compared with 0.33 ( + /-0.70 ) in the STHS group following ischemia and 4 h of reperfusion ( P=0.04 ) . Troponin T was significantly higher in the HTK group compared with the STHS group ( P=0.04 ) . Repeatedly delivered STHS gives better preservation of postischemic mechanoenergetic function and lower troponin T release compared with single dose HTK cardioplegia , indicating improved cardioprotection with STHS Abstract Objectives . To clarify the reliability of the one-shot histidine – tryptophane – ketoglutarate ( HTK ) cardioplegia for right ventricular ( RV ) myocardial protection during mitral surgery , in patients with or without pre-operative RV dysfunction . Design . Sixty patients undergoing isolated mitral surgery were r and omized to myocardial protection with either one-shot HTK or intermittent warm blood cardioplegia ( WBC ) . The RV function was assessed by echocardiography and hemodynamic assessment . Pre-operative tricuspid annular plane systolic excursion ( TAPSE ) , an index of RV systolic function was used to dichotomize groups into patients having impaired ( TAPSE < 15 ) or preserved ( TAPSE ≥ 15 ) RV function . Results . There were no significant intergroup differences in the post-operative indexes of RV function in cases with TAPSE ≥ 15 . In patients having TAPSE < 15 we observed statistically worse RV ejection fraction ( RVEF , 15 % ± 2 % vs. 24 % ± 3 % ) , end-diastolic volume ( RVEDV , 188 mL ± 20 vs. 179 mL ± 14 ) and fractional area change ( RVFAC , 21 % ± 6 % vs. 30 % ± 3 % ) after use of the HTK solution versus patients who received the WBC . These differences were associated with longer mechanical ventilation and ICU times in patients with impaired RV function and receiving HTK cardioplegia . In a sub study ten patients with TAPSE < 15 received intra-operative topical myocardial cooling in addition to HTK . The addition of topical cooling to HTK cardioplegia yielded statistically significant amelioration in post-operative RV function compared with patients who received the HTK solution without topical cooling ( RVEF : 23 % ± 3 % vs. 15 % ± 2 % ; RVEDV : 180 mL ± 9 vs. 188 mL ± 18 ; RVFAC : 8.5 % ± 1 % vs. 6 % ± 2 % ) . Conclusions . The one shot HTK solution offers inferior RV protection compared with WBC , mainly in patients with depressed pre-operative RV function . When adopting HTK cardioplegia the addition of topical cooling is strongly advised OBJECTIVES A single or dual-dose strategy for myocardial protection is attractive in long operations , in avoiding the need to interrupt the procedure to re-administer cardioplegia . We hypothesized that a single administration of Bretschneider histidine-tryptophan-ketoglutarate ( HTK ) crystalloid solution ( Custodiol ) offers myocardial protection comparable with repeated tepid blood cardioplegia . METHODS We review ed a prospect ively compiled single-centre data base containing all adult cardiac procedures performed from January 2005 to January 2011 . Preoperative demographic and investigative data , operative variables and postoperative ( 30-day ) mortality and morbidity were compared between the Custodiol and blood cardioplegia groups . The study primary endpoints were 30-day mortality , return to the operating theatre , myocardial infa rct ion , stroke , postoperative requirement for an intra-aortic balloon pump , new renal failure , prolonged ventilation and re-admission to hospital within 30 days . Propensity score matching was performed to correct for any bias that may have been associated with the usage of Custodiol . RESULTS A total of 1900 cardiac surgical procedures were identified of which 126 ( 7 % ) utilized Custodiol and 1774 ( 93 % ) used blood cardioplegia as the primary cardioplegic agent . After propensity-score matching , we were able to match 71 Custodiol cases one-to-one to those receiving blood cardioplegia . There were no statistically significant differences noted for any of the endpoints studied after propensity-score matching . In particular , the proportion of mortality ( blood cardioplegia : 1 vs Custodiol 4 % , P = 0.63 ) any mortality/morbidity ( blood cardioplegia : 35 vs Custodiol : 39 % P = 0.46 ) was similar between the groups . CONCLUSIONS The use of Custodiol is convenient , simple and at least as safe as tepid blood cardioplegia for myocardial protection in complex cardiac operations . A r and omized prospect i ve comparison of myocardial protection strategies is warranted OBJECTIVE Intermittend , hypothermic aortic cross-clamping ( IAC ) with myocardial fibrillation and cardioplegic arrest ( CA ) have been established both as effective methods for coronary artery bypass surgery ( CABG ) . Nevertheless , there exists controversy about the more beneficial cardioprotective effect of one of these procedures in CABG- patients . METHODS In this prospect i ve study we compared the clinical outcome , ischemic serum-markers ( CK , CK-MB , Troponin I ) , electrocardiogram (ECG)-changes , and hemodynamic data of 103 patients . R and omization in group I ( IAC ; n=52 ) or group II ( CA ; n=51 ) was done consecutively , all data were compared by Student 's t-test or chi(2)-test and P<0.05 was regarded as significant . The Bretschneider-HTK solution was used for cardioplegic arrest . Data were collected before operation , before ischemic arrest , after 5 and 60 min of reperfusion , 1 and 6 h after operation , 1 , 2 and 10 days postoperatively . RESULTS There were no significant differences between both groups regarding general patient data : age ( IAC : 64 . 8+/-9.2 vs. CA : 63.8+/-9.0 years ) , left ventricular function ( ejection fraction : IAC : 62+/-14 vs. CA : 64+/-13 % ) , the amount of bypassed vessels  ( IAC : 3.4+/-0.5 vs. CA : 3.6+/-0.5 ) , total bypass time ( IAC : 113+/-31 vs. CA 108+/-20 min ) . The total time of ischemia was significantly less in the IAC group with 37+/-10 vs. 48+/-10 min in the CA group . In the IAC-group , a higher mortality was noticed ( 7 . 7 vs. 3.9 % ; N.S. ) . This was combined with a significantly higher amount of patients with peak serum-values of CK-MB ( > 40 U/l ) and troponin I ( > 50 ng/ml ) , 17 in the IAC-group ( 33 % ) vs. eight in CA-group ( 16 % ) . Cerebral strokes were seen in two IAC- patients and none in CA- patients ( NS ) . ECG-changes occurred in 22 IAC patients ( 42 % ) vs. 16 CA patients ( 31 % ) ; persistent ischemia related ECG-changes in six IAC ( 11.5 % ) vs. five CA- patients ( 9.8 % ) . CONCLUSIONS Both cardioprotective methods , IAC and HTK-cardioplegia , seem to offer sufficient myocardial protection in normal CABG- procedures . Although neurologic disorders and mort 
    Output:
    
No difference was identified in mortality ; there was a trend for increased incidence of ventricular fibrillation in the Custodiol group that did not reach statistical significance .
No difference was identified in studies that compared Custodiol with other solutions for heart transplant .