Incidence of Cerebral Microemboli in Single-Dose vs. Multidose Cardioplegia in Adult Cardiac Surgery

Cerebral microemboli have been associated with neurocognitive deficits after cardiac operations using cardiopulmonary bypass (CPB). Interventions by the perfusionist and alterations in blood flow account for a large proportion of previously unexplained microemboli. This study compared the incidence of microemboli during cardiac operations using conventional (multidose) and del Nido (single-dose) cardioplegia delivery. Transcranial Doppler ultrasonography was used to detect microemboli in bilateral middle cerebral arteries of 30 adult patients undergoing cardiac operations using CPB and aortic clamping. Multidose conventional blood cardioplegia (CBC) was used in 15 patients and single-dose del Nido cardioplegia (DNC) in 15. Manual count of microemboli during cross-clamp and during administration of cardioplegia was performed. Baseline preoperative characteristics were similar between groups. There were no differences in the ascending aortic atheroma grade (1.4 ± .4 CBC vs. 1.6 ± .7 DNC, p = .44), bypass times (141 ± 36 minutes CBC vs. 151 ± 33 minutes DNC, p = .64), and cross-clamp times (118 ± 32 minutes CBC vs. 119 ± 45 minutes DNC, p = .95). The use of multidose CBC was associated with a seven-fold increase in the number of microemboli per minute of bypass (1.65 ± 1 vs. .24 ± .18 emboli/min DNC, p = .0004). In this prospective pilot study, we found that the use of single-dose cardioplegia strategy led to fewer cerebral microemboli when compared with the traditional multidose approach. Our findings warrant further investigation of various cardioplegia strategies and neurologic outcomes in larger cohorts.

EAST Multicenter Trial on targeted temperature management for hanging-induced cardiac arrest

BACKGROUND

We sought to determine the outcome of suicidal hanging and the impact of targeted temperature management (TTM) on hanging-induced cardiac arrest (CA) through an Eastern Association for the Surgery of Trauma (EAST) multicenter retrospective study.

METHODS

We analyzed hanging patient data and TTM variables from January 1992 to December 2015. Cerebral performance category score of 1 or 2 was considered good neurologic outcome, while cerebral performance category score of 3 or 4 was considered poor outcome. Classification and Regression Trees recursive partitioning was used to develop multivariate predictive models for survival and neurologic outcome.

RESULTS

A total of 692 hanging patients from 17 centers were analyzed for this study. Their overall survival rate was 77%, and the CA survival rate was 28.6%. The CA patients had significantly higher severity of illness and worse outcome than the non-CA patients. Of the 175 CA patients who survived to hospital admission, 81 patients (46.3%) received post-CA TTM. The unadjusted survival of TTM CA patients (24.7% vs 39.4%, p < 0.05) and good neurologic outcome (19.8% vs 37.2%, p < 0.05) were worse than non-TTM CA patients. However, when subgroup analyses were performed between those with an admission Glasgow Coma Scale score of 3 to 8, the differences between TTM and non-TTM CA survival (23.8% vs 30.0%, p = 0.37) and good neurologic outcome (18.8% vs 28.7%, p = 0.14) were not significant. Targeted temperature management implementation and post-CA management varied between the participating centers. Classification and Regression Trees models identified variables predictive of favorable and poor outcome for hanging and TTM patients with excellent accuracy.

CONCLUSION

Cardiac arrest hanging patients had worse outcome than non-CA patients. Targeted temperature management CA patients had worse unadjusted survival and neurologic outcome than non-TTM patients. These findings may be explained by their higher severity of illness, variable TTM implementation, and differences in post-CA management. Future prospective studies are necessary to ascertain the effect of TTM on hanging outcome and to validate our Classification and Regression Trees models.

LEVEL OF EVIDENCE

Therapeutic study, level IV; prognostic study, level III.

Global Cardioplegia Practices: Results from the Global Cardiopulmonary Bypass Survey

Despite the ubiquitous use of cardioplegia in cardiac surgery, there is a lack of agreement on various aspects of cardioplegia practice. To discover current cardioplegia practices throughout the world, we undertook a global survey to document contemporary cardiopulmonary bypass practices. A 16-question, Internet-based survey was distributed by regional specialist societies, targeting adult cardiac anesthesiologists. Ten questions concerned caseload and cardioplegia practices, the remaining questions examined anticoagulation and pump-priming practices. The survey was available in English, Spanish, and Portuguese. The survey was launched in June 2015 and remained open until May 2016. A total of 923 responses were analyzed, summarizing practice in Europe (269), North America (334), South America (215), and Australia/New Zealand (105). Inter-regional responses differed for all questions asked (p < .001). In all regions other than South America, blood cardioplegia was the common arrest technique used. The most commonly used cardioplegia solutions were: St. Thomas, Bretschneider, and University of Wisconsin with significant regional variation. The use of additives (most commonly glucose, glutamate, tris-hydroxymethyl aminomethane, and aspartate) varied significantly. This survey has revealed significant variation in international practice with regards to myocardial protection, and is a reminder that there is no clear consensus on the use of cardioplegia. It is unclear why regional practice groups made the choices they have and the clinical impact remains unclear.

Does the Type of Cardioplegia Solution Affect Intraoperative Glucose Levels? A Propensity-Matched Analysis

Myocardial protection during cardiac surgery is a multifaceted process that is structured to limit injury and preserve function. Evolving techniques use solutions with varying constituents that enter the systemic circulation and alter intrinsic systemic concentrations. This study compared two distinct cardioplegia solutions on affecting intraoperative glucose levels. Data were abstracted from a multi-institutional perfusion registry, including a total of 1,188 propensity-matched cases performed from January through October 2016, at 17 cardiac surgical centers across the United States in which both del Nido and 4:1 cardioplegia were used during the study period. Covariate data included insulin administration, crystalloid cardioplegia volume, diabetes history, glucose at operating room entry, and nine additional variables. Primary and secondary endpoints were the highest intraoperative glucose level and maximum glucose in excess of 180 mg/dL. Mixed-effects multivariable linear and logistic regression models were used to assess the primary and secondary endpoints, respectively, allowing for statistical control of center and surgeon effects. Greater median crystalloid cardioplegia volume was given in the del Nido group (n = 594) 1,040 mL [interquartile range (IQR) = {800, 1,339}] compared with the 4:1 group (n = 594) 466 mL [IQR = {360, 660}] in the 4:1 group (p < .001) despite these groups being statistically indistinguishable in terms of bypass and cross-clamp times as well as seven other patient covariates. More patients required intraoperative insulin drip in the 4:1 group compared with del Nido (65.7% vs. 56.2%, p < .001). Multivariable linear mixed-effects analysis yielded an estimated maximum intraoperative glucose for the del Nido group of 177.8 mg/dL compared with that of the 4:1 group, 183.5 mg/dL-a statistically significant reduction of 5.7 mg/dL (p = .03). Multivariable logistic mixed-effects analysis showed a statistically nonsignificant reduction in the likelihood of crossing the 180 mg/dL threshold for del Nido compared with 4:1 (odds ratio [OR] = .79, p = .214). After controlling for known confounding variables, intraoperative maximum glucose levels for the del Nido group were 5.7 mg/dL lower than that of the 4:1 group; there was limited evidence suggesting a difference between methods in the likelihood of exceeding the threshold of 180 mg/dL intraoperatively. Further research is warranted to examine the differential effects of cardioplegia solution on intraoperative glucose levels.

Does the Type of Cardioplegic Technique Influence Hemodilution and Transfusion Requirements in Adult Patients Undergoing Cardiac Surgery?

During cardiac surgery, myocardial protection is performed using diverse cardioplegic (CP) solutions with and without the presence of blood. New CP formulations extend ischemic intervals but use high-volume, crystalloid-based solutions. The present study evaluated four commonly used CP solutions and their effect on hemodilution during cardiopulmonary bypass (CPB). Records from 16,670 adult patients undergoing cardiac surgery with CPB between February 2016 and January 2017 were reviewed. Patients were classified into one of four groups according to CP type: 4-1 blood to crystalloid (4:1), microplegia (MP), del Nido (DN) and histidine-tryptophan-ketoglutarate (HTK). Covariate-adjusted estimates of group differences were calculated using multivariable logistic and linear mixed effects regression models. The primary end point was intraoperative transfusion of allogeneic red blood cells (RBCs), with a secondary end point of intraoperative hematocrit change. Among all patients, 8,350 (50.1%) received 4:1, 4,606 (27.6%) MP, 3,344 (20.1%) DN, and 370 (2.2%) HTK. Both 4:1 and MP were more likely to be used in patients undergoing coronary revascularization surgery, whereas DN and HTK were seen more often in patients undergoing valve surgery (p < .001). The highest volume of crystalloid CP solution was seen in the HTK group, 2,000 [1,754, 2200], whereas MP had the lowest, 50 [32, 67], p < .001. Ultrafiltration usage was as follows: HTK-84.9%. DN-83.7%, MP-40.1%, and 4:1-34.0%, p < .001. There were no statistically significant differences on the primary outcome risk of intraoperative RBC transfusion. However, statistically significant differences among all but one of the pair-wise comparisons of CP methods on hematocrit change (p < .05 or smaller), with MP having the lowest predicted drift (-7.8%) and HTK having the highest (-9.4%). During cardiac surgery, the administration of different CP formulations results in varying intraoperative hematocrit changes related to the volume of crystalloid solution administered.

Comparison of Warm Blood Cardioplegia Delivery With or Without the Use of a Roller Pump

Various techniques for administration of blood cardioplegia are used worldwide. In this study, the effect of warm blood cardioplegia administration with or without the use of a roller pump on perioperative myocardial injury was studied in patients undergoing coronary artery bypass grafting using minimal extra-corporeal circuits (MECCs). Sixty-eight patients undergoing elective coronary bypass surgery with an MECC system were consecutively enrolled and randomized into a pumpless group (PL group: blood cardioplegia administration without roller pump) or roller pump group (RP group: blood cardioplegia administration with roller pump). No statistically significant differences were found between the PL group and RP group regarding release of cardiac biomarkers. Maximum postoperative biomarker values reached at T1 (after arrival intensive care unit) for heart-type fatty acid binding protein (2.7 [1.5; 6.0] ng/mL PL group vs. 3.2 [1.6; 6.3] ng/mL RP group, p = .63) and at T3 (first postoperative day) for troponin T high-sensitive (22.0 [14.5; 29.3] ng/L PL group vs. 21.1 [15.3; 31.6] ng/L RP group, p = .91), N-terminal pro-brain natriuretic peptide (2.1 [1.7; 2.9] ng/mL PL group vs. 2.6 [1.6; 3.6] ng/mL RP group, p = .48), and C-reactive protein (138 [106; 175] μg/mL PL group vs. 129 [105; 161] μg/mL RP group, p = .65). Besides this, blood cardioplegia flow, blood cardioplegia line pressure, and aortic root pressure during blood cardioplegia administration were similar between the two groups. Administration of warm blood cardioplegia with or without the use of a roller pump results in similar clinically acceptable myocardial protection.

Adolescents with d-transposition of the great arteries corrected with the arterial switch procedure: neuropsychological assessment and structural brain imaging

BACKGROUND

We report neuropsychological and structural brain imaging assessments in children 16 years of age with d-transposition of the great arteries who underwent the arterial switch operation as infants. Children were randomly assigned to a vital organ support method, deep hypothermia with either total circulatory arrest or continuous low-flow cardiopulmonary bypass.

METHODS AND RESULTS

Of 159 eligible adolescents, 139 (87%) participated. Academic achievement, memory, executive functions, visual-spatial skills, attention, and social cognition were assessed. Few significant treatment group differences were found. The occurrence of seizures in the postoperative period was the medical variable most consistently related to worse outcomes. The scores of both treatment groups tended to be lower than those of the test normative populations, with substantial proportions scoring ≥1 SDs below the expected mean. Although the test scores of most adolescents in this trial cohort are in the average range, a substantial proportion have received remedial academic or behavioral services (65%). Magnetic resonance imaging abnormalities were more frequent in the d-transposition of the great arteries group (33%) than in a referent group (4%).

CONCLUSIONS

Adolescents with d-transposition of the great arteries who have undergone the arterial switch operation are at increased neurodevelopmental risk. These data suggest that children with congenital heart disease may benefit from ongoing surveillance to identify emerging difficulties.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000470.

[Blood cardioplegia: advantages and disadvantages]

Blood cardioplegia is worldwilde used during cardiac surgery. It provides a safe myocardial protection during this surgery. All along the year blood cardioplegia has been improved but it's of importance to apply it correctly. This can be a disadvantage during some cardiac surgery technics.

Does Intermittent Aortic Cross Clamping Decrease the Incidence of Atrial Fibrillation after Coronary Bypass Surgery?

Atrial fibrillation (AF) is the most common arrhythmia after coronary artery bypass grafting (CABG). AF is a vexing problem that causes morbidity, prolongs hospital stay, and increases costs. Numerous factors have been suggested to play a role in the development of AF. The aim of this study was to evaluate the effect of intermittent aortic cross clamping (IACC) compared with hypothermic cardioplegic solution (HCS) in the development of postoperative AF. We evaluated data obtained from 345 patients undergoing CABG with HCS (HCS group, n = 212) and IACC (IACC group, n = 173) between April 2004 and August 2005. Diabetes mellitus was observed more often in the HCS group (P < .05), otherwise both groups had similar preoperative characteristics including sex, age, the number of distal anastomoses, left ventricle ejection fraction, history of myocardial infarction, and use of beta-blocker medication. The only statistically significant difference between the groups was higher postoperative Ca-antagonist use in the HCS group. Rates of postoperative AF, however, were significantly lower in the IACC group (21.52%) than that in the HCS group (11.05%; P < .01). Postoperative Ca-antagonist use in the HCS group and smoking in the IACC group were independent predictors of AF after CABG. The incidence of postoperative AF after CABG with IACC was reduced compared with HCS. IACC with ventricular fibrillation may exert a counteractive effect against AF.

Emergency Coronary Artery Bypass Graft Surgery for Acute Coronary Syndrome: Beating Heart Versus Conventional Cardioplegic Cardiac Arrest Strategies

BACKGROUND

Aim of this study was to compare the outcome of beating heart versus conventional coronary artery bypass graft (CABG) strategies in acute coronary syndromes for emergency indications.

METHODS AND RESULTS

638 consecutive patients with acute coronary syndrome (ACS) receiving emergency CABG surgery via midline sternotomy from January 2000 to September 2005 were evaluated. Propensity score analysis was used to predict the probability of undergoing beating heart (BH) (n=240) versus cardioplegic cardiac arrest (CA) (n=398) strategies. Patients presented with stable hemodynamics (n=531) or in cardiogenic shock (CS) (n=107). Hospital and follow-up outcome was compared by propensity score adjusted multiregression analysis. BH included 116 on-pump and 124 off-pump (OPCAB) procedures. There was a propensity to operate CS patients on the beating heart (multivariate odds ratio [OR], 3.8; P=0.001). Under stable hemodynamics significant predictors for BH selection were logEuroSCORE >20% (OR, 2.05), creatinine >1.8 mg/dL (OR, 4.12), complicated percutaneous coronary intervention (OR, 1.88), ejection fraction <30% (OR, 2.64), whereas left main disease (OR, 0.68), circumflex artery (OR, 0.32), and 3-vessel disease (OR, 0.67) indicated preference for cardioplegic arrest. Time from skin incision to culprit lesion revascularization was significantly reduced in BH patients. BH surgery led to a significant benefit in terms of less drainage loss, less transfusion requirement, less inotropic support, shorter ventilation time, lower stroke rate, and shorter intensive care unit stay. In CS, BH was associated with lower incidence of stroke, inotropic support, acute renal failure, new atrial fibrillation and sternal wound healing complications. In CS patients, hospital mortality rate was reduced when using beating heart strategies (P=0.048). Overall survival, major adverse cerebral and cardiovascular event rate, and repeated revascularization was comparable during a 5-year follow-up.

CONCLUSIONS

Beating heart strategies are associated with an improved hospital outcome and comparable long-term results for high-risk patients presenting acute coronary syndrome with or without CS.

Risk of seizures in survivors of newborn heart surgery using deep hypothermic circulatory arrest

OBJECTIVE

To identify pre- and intraoperative variables associated with postoperative acute neurologic events (ANEs), including seizures and coma, in newborn survivors of congenital heart surgery undergoing deep hypothermic circulatory arrest (DHCA), and to risk-stratify this population on the basis of preoperative risk variables for the purpose of designing future neuroprotection trials.

METHODS

Survivors of newborn heart surgery who were enrolled in a neuroprotection trial provided a comprehensive database for the evaluation of pre- and intraoperative variables that influence the postoperative occurrence of ANEs (seizures or coma). Patients with hypoplastic heart syndrome were excluded. After characterization of the study population, stepwise logistic regression, combined with clinical judgment, was used to identify variables that were most likely to be associated with an increased risk of seizures in the study sample and that were most likely to be generalized to other populations.

RESULTS

Data were available on 164 nonhypoplastic left heart syndrome survivors who underwent newborn heart surgery using DHCA. ANEs occurred in 31 (18.9%) including "seizures alone" (n = 28), "coma alone" (n = 2) or "seizures and coma" (n = 1). A preoperative risk model was constructed demonstrating that infants with a genetic condition and aortic arch obstruction had a 47.8% risk of ANEs compared with all other remaining infants, who had a 9.9% risk. It was also found that prolonged DHCA time (>or=60 minutes) can be a significant risk for infants who have a preexisting genetic condition; however, infants who have genetic conditions and do not undergo prolonged DHCA time or have an aortic arch obstruction are not at increased risk of ANEs.

CONCLUSIONS

This study provides new information about the occurrence of ANEs after newborn heart surgery. Seizures or coma, which appeared in approximately 19% of all non-hypoplastic left heart syndrome survivors, were not random events but were significantly associated with specific types of congenital heart disease, the presence of genetic conditions, and prolonged DHCA time. The 3 identified variables permitted individual cases to be assigned to low-, intermediate-, or high-risk categories. Because neonatal seizures are a good surrogate marker of long-term neurologic outcome, these models provide useful information to stratify individual patients for risk of seizures in future neuroprotection trials.

Minimally invasive cardiopulmonary bypass with cardioplegic arrest: a closed chest technique with equivalent myocardial protection

Thoracoscopic cardiac surgery is presently under intense investigation. This study examined the feasibility and efficacy of closed chest cardiopulmonary bypass and cardioplegic arrest in comparison with standard open chest methods in a dog model. The minimally invasive closed chest group (n = 6) underwent percutaneous cardiopulmonary bypass and cardiac venting, as well as antegrade cardioplegic arrest through use of a specially designed percutaneous endovascular aortic occluder and cardioplegic solution delivery system. The control group (n = 6) underwent standard sternotomy and conventional open chest cardiopulmonary bypass, aortic crossclamping, and antegrade cardioplegia. Ischemic arrest time was 1 hour in each group. Ventricular pressures and sonomicrometer segment lengths were recorded before bypass and at 30 and 60 minutes after bypass. Left ventricular function did not differ significantly between the two groups, as demonstrated by measurements of elastance and end-diastolic stroke work. Also, the preload recruitable work area was 69% and 60% of baseline at 30 and 60 minutes after bypass in the minimally invasive group versus 65% and 62% in the conventional control group (p = not significant); the stroke work end-diastolic length relationship was 78% and 71% of baseline in the minimally invasive group at these intervals versus 77% and 74% in the conventional control group (p = not significant). Myocardial temperatures were similar throughout bypass in the two groups, and ultrastructural examination of prebypass and postbypass biopsy specimens showed no differences between groups. These results demonstrate that minimally invasive cardiopulmonary bypass with cardioplegic arrest is as feasible, safe, and effective as conventional open chest cardiopulmonary bypass. Thus current technology may allow wider clinical application of closed chest cardiac surgery.

Aortic arch surgery: pros and cons of selective cerebral perfusion. A multivariable analysis for cerebral injury during hypothermic circulatory arrest

Thirty-five consecutive patients with aortic arch aneurysm who required surgical reconstruction were operated on with the aid of extracorporeal circulation between February 1985 and December 1993. Nineteen patients (54.3%) were treated with hypothermic circulatory arrest (HCA) (Group A) and 16 (45.7%) (Group B) with HCA and selective cerebral perfusion (SCP) through the carotid arteries. Preoperative characteristics didn't show any significant differences between the two groups: mean age was 58.7 +/- 12 vs 62.1 +/- 7, p = ns, male sex 73.6% vs 75%, p = ns; atherosclerotic aneurysms were 57.8% vs 43.7%, p = ns; Type A dissections 42.2% vs 56.3%, p = ns and emergency operation were 68.4% vs 43.7%, p = ns in Groups A and B respectively. For SCP, blood was infused initially at a rate of 200-300 ml/min, maintaining the 30-40% of cerebral blood flow in normothermia, successively, with the aid of transcranial Doppler sonography (TDS) SCP-flow was improved to 500-1000 ml/min. The MHz pulsed TDS was used to measure the middle cerebral artery flow velocity in deep hypothermia before the arrest, in order to adjust the SCP flow during the HCA. In all patients we used open aortic anastomosis; in two cases an extraanatomical ascending-descending aorta was required, and in other two the "elephant trunk" technique was used in case of combined aortic arch and descending aneurysms. The HCA times were similar in the two groups 47.5 +/- 22 vs 47.7 +/- 78, p = ns. Early deaths occurred in 5 patients of the Group A (26.3%) and in 3 patients of the group B (18.7%), p = ns.(ABSTRACT TRUNCATED AT 250 WORDS)

Normothermic retrograde cardioplegia is effective in patients with left ventricular hypertrophy. A prospective and randomized study

Twenty patients with left ventricular hypertrophy (LVH) undergoing isolated aortic valve replacement were prospectively randomized to receive either continuous retrograde normothermic (n = 8) or intermittent retrograde hypothermic (n = 12) methods of myocardial protection. Biopsies of the left ventricular septum were evaluated for ultrastructure and assayed for ATP. There was no mortality, no requirement for intra-aortic balloon pump nor neurological events in any of the patients from either group. Myocardial ATP (warm 23.2 +/- 1.8 nmol/mg protein; cold 22.4 +/- 1.2 nmol/mg protein; p = 0.72) and myocardial CPK-MB (warm 43.6 +/- 5.2 U/l; cold 39.0 +/- 2.5 U/l; p = 0.67) were not significantly different. Ultrastructure was generally well preserved in the biopsies from both groups, with the exception of one patient in the normothermic group. Systemic lactate sampled after 40 minutes of cardiopulmonary bypass was significantly higher in the normothermic group (warm 3.4 +/- 0.27 mmol/l; cold 2.3 +/- 0.21 mmol/l; p = 0.01), however, the myocardial lactate production was not significantly different between the two groups (extraction ratio; warm 0.01 +/- 0.3; cold 0.13 +/- 0.1; p = 0.45). We conclude that the continuous normothermic retrograde method of myocardial protection is effective in patients with left ventricular hypertrophy; however, the higher systemic lactate levels using this technique raises concerns regarding the adequacy of systemic perfusion at 37 degrees C.

Myocardial protection for acquired heart disease surgery: results of a national survey

To study current myocardial protection practices, all 4,393 United States board-certified thoracic surgeons were surveyed in 1992. Of the 1,413 respondents (32% total response), 936 are in active practice dealing with acquired heart disease. Based on their frequency of cases, respondents perform approximately 32% of all acquired heart disease operations in the United States yearly and individually average 157 patients/year. For myocardial protection, 98% of respondents routinely use cardioplegic arrest. The primary method of cardioplegia delivery is antegrade 36%, retrograde 4%, and a combination of antegrade and retrograde 60%. The types of cardioplegic solutions used are blood 72%, crystalloid 22%, and oxygenated crystalloid 6%. Continuous warm blood cardioplegia is used by 10% of respondents, whereas most (75%) have adopted a skeptical "wait and see" attitude or have abandoned it (6%). Overall, most surgeons (78%) report that they are very satisfied with their present methods of myocardial protection, whereas only 2% are dissatisfied. Still, the three areas believed most important for future research are reperfusion injury (74%), acutely infarcting myocardium (61%), and metabolic enhancers in cardioplegia (58%).

A new frontier for cardiac therapy. Principles and practice of aerobic cardiac surgery

As recently reported in the literature, aerobic cardiac surgery (normothermic total body perfusion + continuous normothermic blood cardioplegia) might achieve optimal heart protection by virtually eliminating myocardial ischemia during aortic cross-clamping. Two-hundred and fifty consecutive patients underwent cardiac surgery by this technique. Mean cross-clamp time was 72.6 +/- 30.7 minutes. Ten patients (4%) died, 20 (8%) needed major inotropic support and 8 (3.2%) required circulatory assistance. Two-hundred and twenty-three patients (89.2%) returned spontaneously to normal sinus rhythm and 8 (3.2%) had evidence of perioperative myocardial infarction. Nineteen patients (7.6%) had a cross-clamp time longer than 120 minutes and no significant difference in mortality was observed with those undergoing a shorter cross-clamping. When comparing 154 patients receiving retrograde continuous normothermic blood cardioplegia induction with 46 receiving antegrade induction, no difference was found in perioperative parameters, mortality and morbidity. By univariate analysis, impaired preoperative LV performance was identified as the only risk factor for operative mortality. In our experience aerobic cardiac surgery appears most suitable for emergency and redo operations, extensive coronary revascularization, complex mitral reconstruction, aortic valve replacement (particularly with unstented biological prostheses), cardiac transplants and whenever two or more valvular and/or coronary procedures are associated. Retrograde induction is as effective as antegrade and simplifies the technique, facilitating unmodified continuous normothermic blood cardioplegia in different anatomical and clinical situations.

Coronary artery bypass surgery: current practice in the United Kingdom

OBJECTIVE

To assess current clinical practice in coronary artery bypass surgery and compare it with a previous survey conducted five years ago.

SETTING

United Kingdom.

DESIGN

Postal questionnaires were sent in March 1993 to 120 consultant cardiac surgeons currently performing coronary artery bypass surgery. 104 (87%) were returned by May 1993.

RESULTS

The 104 surgeons who returned the questionnaire performed an estimated total of 25,234 coronary artery bypass operations in 1992 with an average case load per surgeon similar to that in 1987 (243 v 214, NS). The internal mammary artery was regarded as the conduit of choice by 101 surgeons (97%) and was used in 93% of bypass grafts to the left anterior descending coronary artery compared with 73% in 1987 (p < 0.001) but only in 7% of grafts to the circumflex and right coronary systems. There was also a significant increase in the number of surgeons using both internal mammary arteries (88% v 59%, p < 0.01) but only a small increase in those using the internal mammary artery as a sequential graft (55% v 44%, NS). The age of the patient remains one of the main contraindications to the use of the internal mammary artery (40%), together with insufficient mammary flow (42%), endarterectomy (22%), and unstable angina (17%). The right gastroepiploic and inferior epigastric arteries were used only occasionally (3%) when the internal mammary artery or the saphenous vein were not available. Most surgeons (96%) still advocate the use of aspirin to enhance graft patency, with 87% of surgeons continuing treatment indefinitely, compared with 50% in the previous survey (p < 0.001). As for methods of myocardial protection, 72% of surgeons used cardioplegic arrest whereas 28% preferred intermittent aortic cross clamping and fibrillation.

CONCLUSIONS

It is the consensus among British cardiac surgeons that the internal mammary artery is the graft conduit of choice. Its use has been significantly extended over the past five years (1987 to 1992) suggesting a quick response to advancing scientific knowledge. The use of alternative arterial conduits is still limited, perhaps as a reflection of the relative lack of information on their long-term performance. The recently advocated technique of retrograde cardioplegia and continuous warm cardioplegia is not yet popular.

Evaluation of cerebral metabolism and quantitative electroencephalography after hypothermic circulatory arrest and low-flow cardiopulmonary bypass at different temperatures

Although widely used for repair of complex cardiovascular pathologic conditions, long intervals of hypothermic circulatory arrest and low flow cardiopulmonary bypass may both result in cerebral injury. This study examines cerebral hemodynamics, metabolism, and electrical activity to evaluate the risks of cerebral injury after 60 minutes of hypothermic circulatory arrest at 8 degrees C, 13 degrees C, and 18 degrees C, compared with 60 minutes of low flow cardiopulmonary bypass at 18 degrees C. Thirty-two puppies were randomly assigned to one of four experimental groups and centrally cooled to the appropriate temperature. Serial evaluations of quantitative electroencephalography, radioactive microsphere determinations of cerebral blood flow, calculations of cerebral oxygen consumption, cerebral glucose consumption, cerebral vascular resistance, cerebral oxygen extraction, systemic oxygen metabolism, and systemic vascular resistance were done. Measurements were obtained at baseline (37 degrees C), at the end of cooling, at 30 degrees C during rewarming, and at 2, 4, and 8 hours after hypothermic circulatory arrest or low flow cardiopulmonary bypass. At the end of cooling, cerebral vascular resistance remained at baseline levels in all groups, but systemic vascular resistance was increased in all groups. Cerebral oxygen consumption became progressively lower as temperature was reduced: it was only 5% of baseline at 8 degrees C; 20% at 13 degrees C; and 34% and 39% at 18 degrees C. Quantitative electroencephalography was silent in the 8 degrees C and 13 degrees C groups, but significant slow wave activity was present at 18 degrees C. Systemic vascular resistance and cerebral oxygen consumption returned to baseline values in all groups by 2 hours after hypothermic circulatory arrest or low flow cardiopulmonary bypass, but cerebral vascular resistance remained elevated at 2 and 4 hours, not returning to baseline until 8 hours after hypothermic circulatory arrest or low flow cardiopulmonary bypass. All but two of the long-term survivors (27 of 32) appeared neurologically normal; after hypothermic circulatory arrest at 8 degrees and 18 degrees C two animals had an unsteady gait. Comparison of quantitative electroencephalography before operation and 6 days after operation showed a significant increase in slow wave activity (delta activity) after hypothermic circulatory arrest and low flow cardiopulmonary bypass at 18 degrees C, a change that suggests possible cerebral injury. Although undetected after operation by simple behavioral and neurologic assessment, significant differences in cerebral metabolism, vasomotor responses, and quantitative electroencephalography do exist during and after hypothermic circulatory arrest and low flow cardiopulmonary bypass at various temperatures and may be implicated in the occurrence of cerebral injury.(ABSTRACT TRUNCATED AT 400 WORDS)

Hypothermic potassium cardioplegia impairs myocyte recovery of contractility and inotropy

Acute postoperative left ventricular dysfunction after hypothermic, crystalloid potassium cardioplegia occasionally occurs. This project examined myocyte contractility and inotropic responsiveness after hypothermic arrest with and without potassium cardioplegia. Isolated swine left ventricular myocytes were placed in a thermostatically controlled chamber (37 degrees C) that contained a standard cell medium, pulse stimulated at 1 Hz, and steady-state contractions were measured by computer-assisted video microscopy with and without isoproterenol (25 nmol/L). After baseline measurements were taken the myocytes were randomly assigned to the following treatments: (1) control group with infusion of 37 degrees C crystalloid solution and maintained at 37 degrees C for 3 hours (n = 23), (2) hypothermia group with infusion of 4 degrees C crystalloid without potassium and stored at 4 degrees C for 3 hours (n = 22), (3) hypothermic cardioplegia group with infusion of a crystalloid cardioplegia (oxygenated, buffered 4 degrees C Ringer's solution with 24 mEq/L K+) and then stored at 4 degrees C for 3 hours (n = 35). After treatment the myocytes were then rewarmed to 37 degrees C by infusion of medium, and contractile measurements were repeated. In the control group, the percent and velocity of shortening were identical to those in baseline measurements: 6.4% +/- 0.4% and 53 +/- 5 microns/sec, respectively, and these values remained unchanged in the hypothermia group: 6.5% +/- 0.4% and 51 +/- 3 microns/sec, respectively. However, in the hypothermic cardioplegia group, the percent and velocity of shortening were significantly lower with rewarming: 4.8% +/- 0.4% and 35 +/- 3 microns/sec, respectively, p < 0.05). Isoproterenol caused increased percent and velocity of shortening in both the control and hypothermia groups: 10.0% +/- 0.6% and 9.5% +/- 0.9% and 81.6 +/- 8 microns/sec and 71.4 +/- 8 microns/sec, respectively. This response was significantly blunted in the cardioplegia group (8.9% +/- 0.8% and 56.9 +/- 7 microns/sec, p < 0.05). With an isolated myocyte system that is independent of extracellular and perfusion effects, hyperkalemic cardioplegic solution resulted in depressed myocyte contractile performance after rewarming. Potassium cardioplegia also caused a blunted inotropic responsiveness on rewarming. A potential contributory factor for the depressed left ventricular function after the use of potassium cardioplegia is a direct depression in myocyte contractility.

A survey of cardiopulmonary bypass perfusion practices in Australia in 1992

Twenty-four cardiopulmonary bypass (CPB) perfusion units around Australia were surveyed to determine the characteristics of CPB perfusion as practised in Australia in 1992. Twenty completed survey forms were received. Findings were compared with those of a similar study performed by one of the authors for the year 1986. The field of CPB perfusion continues to expand both in terms of numbers of cases and increasing technological complexity. The major technological changes evident are the now clear dominance of membrane over bubble oxygenators and the proliferation of inline SvO2 monitoring devices. The greatest change in practice has been to the virtually universal use of cardioplegia. There remains considerable variation in the composition of the cardioplegia solutions used in the responding units. A range of minimum perfusion pressures for CPB is noted, whereas most units employ similar minimum perfusion flows. Methods of central nervous system and renal protection are mainly hypothermia and diuretics, respectively, with a scattering of other techniques. Staffing of CPB perfusion units is essentially unchanged since 1986 and at least five units had no medical perfusionist appointed in 1992.

[Anterograde and retrograde cardioplegia in myocardial revascularization. An intraoperative contrast echographic study]

The aim of this study was to assess the distribution of antegrade and retrograde cardioplegia with intraoperative contrast echocardiography in patients undergoing coronary artery bypass grafting. Fifteen patients with chronic stable angina pectoris and severe coronary artery disease were studied. The severity of coronary artery disease was assessed at coronary angiography, using the Jeopardy Score System. The presence and the extent of collateral circulation was evaluated on the basis of preoperative coronary angiography and graded as: absent or poor; good or excellent. Coronary revascularization was carried out during extracorporeal circulation and myocardial protection was performed with antegrade (aortic root) and retrograde (right atrial) cardioplegia. The echo contrast agent was sterilely prepared 1 hour prior to surgery and consisted of a solution of sonicated 5% human albumin microbubbles. Two ml of sonicated albumin were injected along with antegrade cardioplegia and 4 ml with retrograde cardioplegia. The echocardiographic images were obtained with transesophageal echocardiography in the transgastric left ventricular short-axis view. Images were recorded on videotape for off-line planimetric measurement of percent myocardial opacification. Data were analyzed with the analysis of variance. Multiple comparisons were made with Student's paired t test and using Bonferroni's correction. Myocardial opacification was 58.9 +/- 12.9% during antegrade cardioplegia and 77.5 +/- 16.4% during retrograde cardioplegia (p = 0.003). This overall difference was mainly due to the impact of collateral circulation in the distribution of antegrade cardioplegia. Patients with absent or poor collateral circulation showed a lower degree of myocardial opacification than patients with good or excellent myocardial opacification (44.3 +/- 12.0% versus 64.2 +/- 8.6%; p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Pediatric myocardial protection in the United States: a survey of current clinical practice

A nationwide survey of institutions in the United States that perform congenital heart disease surgery was conducted to obtain an overview of the current use of myocardial protection in pediatric patients (aged 0-16 years). One hundred and one (55%) of 183 institutions responded, completing a 4-page questionnaire about pediatric cases in 1989. A total of 12,072 cases were represented. Caseloads ranged from 7 to 498 at these institutions (mean 124, median 30). Cardioplegia was used by 100 institutions (44 blood, 45 crystalloid, 11 both). Administration was guided by formulas alone in 69 and by clinical criteria alone in 32. A wide variety of compositions of cardioplegic solutions was found with no preference for any particular type. No correlation between caseloads and cardioplegic solutions was found. Hypothermia was used by all institutions, with a mean of 25.8 +/- 3.5 degrees C for a simple ventricular septal defect closure. Deep hypothermia and circulatory arrest were used in 3048 cases (25.2%). A clear trend indicated that circulatory arrest was used more frequently in larger institutions (p less than 0.0001). Fibrillation as a strategy was used in 45 institutions. Twenty-five institutions changed cardioplegia technique during 1989. The findings suggest that, even though no consensus exists about its ideal composition, cardioplegia in conjunction with hypothermia is currently the strategy most often used for pediatric myocardial protection.