Efficacy and safety of an insulin infusion protocol during and after cardiac surgery.

AIM: Perioperative tight blood glucose (BG) control using insulin therapy after major surgery is a difficult, time-consuming task that also raises some concerns over the risk of severe hypoglycaemia. The aim of the present prospective study was to evaluate the efficacy and safety of an insulin therapy protocol in use at our institution. METHODS: A total of 230 consecutive patients (mean+/-SD age: 67+/-11 years; diabetic patients: n=62) undergoing cardiac surgery (coronary artery bypass grafting: n=137; 20% off-pump) or intrathoracic aortic (n=10) surgery were included. BG control was managed according to an insulin therapy protocol, described by Goldberg et al. (2004) [11], in use for 6 months in our intensive care unit. Insulin infusion rate and frequency of BG monitoring were both adjusted according to: (1) the current BG value; (2) the previous BG value; and (3) the current insulin infusion rate. Efficacy was assessed by the percentage of time spent at the target BG level (100-139 mg/dL) intraoperatively and during the first 2 postoperative days (POD). RESULTS: All patients received postoperative insulin therapy. Patients spent 57.3% and 69.7% of time within the BG target range on POD 1 and 2, respectively. The percentage of time was significantly higher in nondiabetics than in diabetics. Mean BG measurements per patient intraoperatively, on POD 1 and on POD 2 were 4+/-1, 10+/-2 and 7+/-2, respectively. No patient experienced any severe hypoglycaemic events (BG<50mg/dL). CONCLUSION: This study showed that a BG target of 100-139 mg/dL can be safely achieved with an insulin therapy protocol that can be routinely used in everyday clinical practice.

Blood warm reperfusion: a necessary adjunct to heart-valve surgery in low-risk patients?

AIM: The aim of this prospective, randomized study was to determine whether blood warm reperfusion improves myocardial protection provided by cold crystalloid cardioplegia in patients undergoing first-time elective heart-valve surgery, using cardiac troponin I release as the criterion for evaluating the adequacy of myocardial protection. METHODS: Seventy patients with a left ventricular ejection fraction greater than 40% were randomly assigned to 1 of 2 myocardial protection strategies: 1) cold crystalloid cardioplegia with no reperfusion or 2) cold crystalloid cardioplegia followed by 2-minute blood warm reperfusion before aortic unclamping. Cardiac troponin I concentrations were measured in serial venous blood samples drawn immediately prior to cardiopulmonary bypass and after aortic unclamping at 6, 9, 12, and 24 h. RESULTS: Randomization produced 2 equivalent groups. The total amount of cardiac troponin I released (7.17+/- 14.8 mg in the crystalloid cardioplegia with no reperfusion group and 5.82+/-4.66 mg in the crystalloid cardioplegia followed by blood warm reperfusion group) was not different (P > 0.2). Cardiac troponin I concentration did not differ for any sample in either of the 2 groups. The total amount of cardiac troponin I released was higher in patients who required inotropic support (9.14 +/-16.2 mg) than those who did not (4.73+/-4.52 mg; P = 0.009). CONCLUSIONS: Our study shows that adding blood warm reperfusion to cold crystalloid cardioplegia provides no additional myocardial protection in low-risk patients undergoing heart-valve surgery.

["Mammary loop" technique--new method of multiple coronary revascularization using internal mammary arteries]. / Tehnica "buclei mamare" o noua metoda de revascularizare coronara multipla folosind arterele mamare interne.

The internal mammary arteries are "the gold standard" conduits for coronary by-pass because their' s patency is superior to the saphenous graft. There are some surgical techniques which allow to use the entire length of the mammary arteries: the Y graft, the T graft and the pi graft. We describe recently the "mammary loop" technique that allows to make a Y graft using only one internal mammary artery. This technique also simplifies the construction of a pi graft. In this article we present the variants of this technique and discuss the indications and our early experience results.

[Myocardial microdialysis. Importance and potential in cardiovascular research]. / Microdialyse myocardique. Intérêt et potentiel en recherche cardio-vasculaire.

The microdialysis expanded mainly in the field of the neuro- and the dermopharmacology with the study of the transmitters released in the central nervous system and derm. Since ten years, this tool gained other disciplines such as cardiology and cardiovascular surgery. Indeed, the collection and the study of the molecules released in the myocardic interstitial fluid without deteriorating it functioning made microdialysis a powerful tool in the study of the extracellular environment of the cardiomyocyte. The purpose of this study is to point out the principle of the microdialysis and to show its various uses in the field of cardiovascular pharmacology.

Endovascular treatment of the traumatic rupture of the aortic isthmus.

The traumatic rupture of the aortic isthmus is a dehiscence of all or part of the aortic wall, occurring as a result of a closed thoracic trauma. Standard surgical technique requires left thoracotomy, aortic cross-clamping and use of the cardiopulmonary by-pass to prevent ischemic complications, in special the neurologic and visceral ones. The endovascular treatment of these lesions is a more simple solution and there are recent reports on the stent-grafting of the isthmic rupture of the thoracic aorta. We report three cases of successful endovascular repair of the aortic isthmic rupture and we discuss the emergency indications, the advantages and the limits of this technique.

[Effects of nitric oxide on cardioprotection prior to ischemia-reperfusion]. / Effets du monoxyde d'azote sur la cardioprotection avant l'ischémie-reperfusion.

This study aimed at evaluating the role of nitric oxide (NO) when generated 24 h prior to ischemia-reperfusion. Three groups were studied in an isolated buffer-perfused heart model: Control (saline = 3.3 mL/kg, n = 10), the precursor of NO, L-arginine, (500 mg/kg, n = 10) and an inhibitor of NO synthase, L-NAME, (10 mg/kg, n = 9). All groups were injected intraperitoneally 24 h before heart extraction. Nitrites, nitrates (an index of nitric oxide release) and cardiac troponine I were assayed. During the reperfusion period, there was a low release of nitric oxide and cardiac troponine I associated with improved recovery of post-ischemic myocardial function. These results indicate that in this model, the pre-treatment improved myocardial function and thus, NO could play a role as a trigger and not as a mediator of cardioprotection.

False lumen patency as a predictor of late outcome in aortic dissection.

Aortic dissection (AD) is a disease with a high-risk of mortality. Late deaths are often related to complications in nonoperated aortic segments. Between 1984 and 1996, we retrospectively analyzed the data of 109 patients with acute AD (81 men and 28 women; average age 61 +/- 14 years). All imaging examinations were reviewed, and a magnetic resonance imaging examination was performed at the time of the study. Aortic diameters were measured on each aortic segment. Predictive factors of mortality were determined by Cox's proportional hazard model, in univariate and multivariate analyses, using BMDP statistical software. Follow-up was an average of 44 +/- 46 months (range 24 to 164). Actuarial survival rates were 52%, 46%, and 37% at 1, 5, and 10 years, respectively, for type A AD versus 76%, 72%, and 46% for type B AD. Predictors of late mortality were age >70 years and postoperative false lumen patency of the thoracic descending aorta (RR 3.4, 95% confidence intervals 1.20 to 9.8). Descending aorta diameter was larger when false lumen was patent (31 vs 44 mm; p = 0.02) in type A AD. Furthermore, patency was less frequent in operated type A AD when surgery had been extended to the aortic arch. Thus, patency of descending aorta false lumen is responsible for progressive aortic dilation. In type A AD, open distal repair makes it possible to check the aortic arch and replace it when necessary, decreases the false lumen patency rate, and improves late survival.

Myocardial fixation of anticardiac troponin I antibody and cardiac troponin I release.

BACKGROUND: The threefold aim of this experimental study was to test the correlation of cardiac troponin I released to myocardial infarction size and myocardial fixation of anticardiac troponin I antibody and to determine how long after myocardial infarction the measure of cardiac troponin I concentration can evaluate myocardial infarction size. METHODS: Forty rabbits were assigned either to a control group or to an experimental preconditioned group. Infarction was obtained by tightening a snare around the left anterior descending artery. Serial venous blood samples were drawn for measurement of cardiac troponin I. The rabbits were sacrificed at 72 hours and a histological study was performed to determine the infarct size and the size of the area void of fixation of anticardiac troponin I antibody. RESULTS: There was a linear correlation between the total amount of CTn I released and both infarct size (r=0.45, p<0.02) and the size of the area void of anti-cardiac troponin I antibody (r=0.47, p<0.02). These two sizes were strongly correlated (r=0.95, p<0.02). The hour 9 CTn I sample was the best correlated with both the infarct size (r=0.47, p<0.02) and the size of area void of anticardiac troponin I antibody (r=0.45, p<0.02). CONCLUSIONS: Our study shows that: 1) cardiac troponin I release is correlated to both myocardial infarction size and the size of area void of fixation of anticardiac troponin I antibody, 2) the area void of anticardiac troponin I antibody fixation includes the whole ischemic area, and 3) evaluation of myocardial infarction size can be obtained by CTn I concentration as early as the ninth hour.

Perceived health status in patients over 70 before and after open-heart operations.

AIM: to evaluate improvement and predictors of improvement in patients' perceived health status after cardiac surgery in older patients. METHODS: three hundred and seventy-seven patients from three different departments of cardiac surgery completed the Nottingham Health Profile questionnaire before and 1 and 2 years after open-heart surgery. We analysed pre- and postoperative data and pre- and postoperative Nottingham Health Profile scores. RESULTS: the mean age was 74+/-3 years. The comparison between pre- and postoperative scores showed an improvement in all but the social isolation section. Logistic regression showed that the predictors of patients who became worse after surgery were (i) in the energy section: age over 75 [odds ratio (OR) = 1.8, 95% confidence interval (CI) = 1.02-3.2], coronary artery disease (OR = 2.4, 95% CI = 1.04-3.6) and postoperative events (OR = 1.9, 95% CI = 1.01-3.7); (ii) in the physical mobility section: diabetes mellitus (OR = 2.4, 95% CI = 1.2-4.7); and (iii) in the social isolation section: physical mobility impairment (OR = 3.4, 95% CI = 1.3-8.7). CONCLUSIONS: cardiac surgery improves perceived health status in patients over 70. This improvement is better for those undergoing aortic valve replacement than for those undergoing coronary artery bypass surgery. Comparison with reference scores for a standard population shows that, even when successful, cardiac surgery results in fatigue and persistent sleep disturbance in older patients.

Preoperative quality of life as a predictive factor of 3-year survival after open heart operations.

BACKGROUND: The aim of this prospective study was twofold: to determine the evolution of quality of life in heart surgery patients through the first 3 postoperative years using the Nottingham Health Profile questionnaire and to determine whether preoperative quality of life influences 3-year survival. METHODS: From January to July 1994, 215 patients underwent elective open heart operation in our department. Patients filled in the Nottingham Health Profile questionnaire five times: preoperatively, postoperatively at month 3, and at each anniversary of their operation for 3 years. The evolution of quality of life scores through time were compared using analysis of covariance with repeated measures. Analysis of 3-year survival prognostic factors was achieved using the Cox proportional hazards model. RESULTS: Quality of life scores varied through time, but not significantly. Multivariate analysis showed two independent risk factors to influence 3-year survival: dyspnea class (III-IV versus I-II, relative risk = 2.80, 95% confidence interval = 1.2 to 6.5) and the energy section of the Nottingham Health Profile questionnaire (relative risk = 1.02 by unit, 95% confidence interval = 1.01 to 1.03). CONCLUSIONS: Our study shows quality of life scores to be stable for the first 3 years after operation and the preoperative energy score to be predictive of 3-year survival.

Intermediate lukewarm (20 degrees c) antegrade intermittent blood cardioplegia compared with cold and warm blood cardioplegia.

BACKGROUND: In the field of intermittent antegrade blood cardioplegia, 3 levels of temperature are commonly used: (1) cold (8 degrees C); (2) tepid (29 degrees C); and (3) warm (37 degrees C). Given the 21 degrees C spread and the metabolic changes that can occur between cold (8 degrees C) and tepid (29 degrees C) cardioplegia, we thought it worthwhile to test a temperature halfway between the cold and tepid levels. The aim of this study was to test the quality of myocardial protection provided by intermediate lukewarm (20 degrees C) cardioplegia by comparing it with cold and warm cardioplegia. Protection was assessed by measuring cardiac troponin I release. METHODS: One hundred thirty-five patients undergoing coronary artery bypass grafting were enrolled in a prospective randomized trial comparing cold (8 degrees C), intermediate lukewarm (20 degrees C), and warm (37 degrees C) antegrade intermittent blood cardioplegia. Cardiac troponin I concentrations were measured in serial venous blood samples. RESULTS: The total amount of cardiac troponin I released was significantly higher in the cold group (4.7 +/- 2.3 microg) than in the intermediate lukewarm (3.4 +/- 2.0 microg) or the warm (3.1 +/- 2.7 microg) groups. The cardiac troponin I concentration was significantly higher at hour 6 in the intermediate lukewarm group (1. 23 +/- 0.55 microg/L) than in the warm group (0.89 +/- 0.50 microg/L). CONCLUSIONS: Intermittent antegrade intermediate lukewarm blood cardioplegia is appropriate and clinically safe. Cardiac troponin I release suggests that intermediate lukewarm cardioplegia is better than cold cardioplegia but less effective than warm cardioplegia in low-risk patients. We therefore recommend the use of warm cardioplegia in low-risk patients.

Determination of cardiac troponin I forms in the blood of patients with acute myocardial infarction and patients receiving crystalloid or cold blood cardioplegia.

To determine the forms of cardiac troponin I (cTnI) circulating in the bloodstream of patients with acute myocardial infarction (AMI) and patients receiving a cardioplegia during heart surgery, we developed three immunoenzymatic sandwich assays. The first assay involves the combination of two monoclonal antibodies (mAbs) specific for human cTnI. The second assay involves the combination of a mAb specific for troponin C (TnC) and an anti-cTnI mAb. The third assay was a combination of a mAb specific for human cardiac troponin T (cTnT) and an anti-cTnI mAb. Fifteen serum samples from patients with AMI, 10 serum samples from patients receiving crystalloid cardioplegia during heart surgery, and 10 serum samples from patients receiving cold blood cardioplegia during heart surgery were assayed by the three two-site immunoassays. We confirmed that cTnI circulates not only in free form but also complexed with the other troponin components (TnC and cTnT). We showed that the predominant form in blood is the cTnI-TnC binary complex (IC). Free cTnI, the cTnI-cTnT binary complex, and the cTnT-cTnI-TnC ternary complex were seldom present, and when present, were in small quantities compared with the binary complex IC. Similar results were obtained in both patient populations studied. These observations are essential for the development of new immunoassays with improved clinical sensitivity and for the selection of an appropriate cTnI primary calibrator.

Warm reperfusion and myocardial protection.

BACKGROUND: The aim of this study was to determine whether warm reperfusion improves myocardial protection with cardiac troponin I as the criteria for evaluating the adequacy of myocardial protection. METHODS: One hundred five patients undergoing first-time elective coronary bypass surgery were randomized to one of three cardioplegic strategies of either (1) cold crystalloid cardioplegia followed by warm reperfusion, (2) cold blood cardioplegia followed by warm reperfusion, or (3) cold blood cardioplegia with no reperfusion. RESULTS: The total amount of cardiac troponin I released tended to be higher in the cold blood cardioplegia with no reperfusion group (3.9+/-5.7 microg) than in the cold blood cardioplegia followed by warm reperfusion group (2.8+/-2.7 microg) or the cold crystalloid cardioplegia followed by warm reperfusion group (2.8+/-2.2 microg), but not significantly so. Cardiac troponin I concentration did not differ for any sample in any of the three groups. CONCLUSIONS: Our study showed that the addition of warm reperfusion to cold blood cardioplegia offers no advantage in a low-risk patient group.

Crystalloid versus cold blood cardioplegia and cardiac troponin I release.

BACKGROUND: Cardiac troponin I (CTnI) has been shown to be a marker of myocardial injury. The aim of this study was to compare antegrade crystalloid cardioplegia with antegrade cold blood cardioplegia with warm reperfusion using CTnI release as the criteria for evaluating the adequacy of myocardial protection. METHODS AND RESULTS: Seventy patients were randomly assigned to receive crystalloid or blood cardioplegia. CTnI concentrations were measured in serial venous blood samples drawn just before cardiopulmonary bypass and after aortic unclamping at 6, 9, 12, and 24 hours and daily thereafter for 5 days. ANOVA with repeated measures was performed to test the effect of the type of cardioplegia on CTnI release. The total amount of CTnI released was higher in the crystalloid cardioplegia group than in the blood cardioplegia group (11.2 +/- 8.9 versus 7.8 +/- 8.6 micrograms, P < .02). CTnI concentration was significantly higher in the crystalloid group than in the blood group in the samples drawn at hours 9 and 12. Three patients in each group had ECG evidence of perioperative myocardial infarction. Eight patients in the crystalloid group and five patients in the blood group had CTnI evidence of perioperative myocardial infarction. CTnI release was significantly lower in patients requiring no electrical defibrillation after aortic unclamping. CONCLUSIONS: Cold blood cardioplegia followed by warm reperfusion is beneficial in an unselected group of patients with a preserved left ventricular function undergoing an elective first coronary artery bypass grafting. CTnI allowed the diagnosis of small perioperative necrotic myocardial areas. The need for electrical defibrillation after aortic unclamping was related to a higher release of CTnI. A further study is necessary to determine whether this technique was beneficial because of cold blood cardioplegia, warm reperfusion, or both.

Effects of myocardial ischemia on the release of cardiac troponin I in isolated rat hearts.

BACKGROUND: The twofold aim of this experimental study was (1) to verify the correlation between the duration of ischemia and concentration of cardiac troponin I and (2) to compare the release of cardiac troponin I with histologic findings. METHODS: Experiments were done on 18 rat hearts, which were perfused according to the Langendorff method, immediately after excision in group I (control group) and after immersion for 3 hours (group II) and 6 hours (group III) in St. Thomas' Hospital solution at 4 degrees C. During reperfusion, the release of cardiac troponin I, creatine kinase isoenzyme MB, and lactate dehydrogenase, the recovery of left ventricular pressure, and heart rates were compared among the three groups. After the experiment, three samples of myocardium (left ventricle, right ventricle, and septum) were taken for histologic examination. RESULTS: Cardiac troponin I concentration was significantly higher in group III than in groups I and II and in group II compared with group I. Cardiac troponin I concentration increased as the ischemic period increased. The relation between cardiac troponin I release and ischemic duration tended to be linear. Creatine kinase MB and lactate dehydrogenase concentrations did not differ from one group to the other. Left ventricular pressure was not significantly different among the groups. In the control group, no heart had more than 10% of the myocytes affected. One of six hearts in group II and three of six in group III had more than 10% of myocytes affected. CONCLUSION: This experimental study showed (1) that cardiac troponin I is an early marker of ischemic injury and (2) that cardiac troponin I concentration increases as the ischemic period increases. Early cardiac troponin I release appears to correlate with the extent of ischemic injury in rats undergoing buffer perfusion.

Crystalloid cardioplegia route of delivery and cardiac troponin I release.

BACKGROUND: Cardiac troponin I (CTn I) has been shown to be a marker of myocardial injury. Incomplete distribution of cardioplegic solution may be responsible for injury in jeopardized myocardial areas. The aim of this study was to compare CTn I release with respect to the route of delivery of crystalloid cardioplegia, either antegrade only or initially antegrade followed by retrograde cardioplegia for the remainder of the operation, in patients undergoing elective coronary artery bypass grafting. METHODS: Sixty patients were randomly assigned to one of two cardioplegia groups. Cardiac troponin I concentrations were measured in serial venous blood samples drawn just before cardiopulmonary bypass and after aortic unclamping at 6, 9, 12, and 24 hours and daily thereafter for 5 days. Analysis of variance with repeated measures was performed to test the effect of route of delivery, coronary disease, collateral circulation, risk of cardioplegia maldistribution, and number of grafts on release of CTn I. RESULTS: Compared with the antegrade route, the combined route offered no advantage in an unselected group of patients undergoing an elective first cardiac operation and having preserved left ventricular function. The CTn I concentration did not differ between groups for any of the samples considered. In patients with major left main coronary artery stenosis, CTn I release was significantly higher at hour 9 in the antegrade group than in the group with combined delivery. CONCLUSIONS: A combined route of delivery of crystalloid cardioplegia is beneficial in patients with major stenosis of the left main coronary artery. Cardiac troponin I sensitivity is relevant in this study. Release of CTn I should be useful in determining the best form of myocardial protection for each patient.

Inter-observer reliability in the interpretation of coronary angiograms.

The interpretation of coronary angiograms is indispensable in determining procedure in coronary surgery. The aim of this study was to measure the overall reliability of a group of surgeons in the interpretation of coronary angiograms, surgical procedure and the evaluation of operative risk. Ten coronary angiograms were interpreted by eight cardiac surgeons at four different medical centers. Evaluation of coding discrepancies, in this case of multiple raters applying an ordinal-scale classification scheme (0, 1, 2) with no expert yardstick available for coding, was explored by a two-way random factor analysis of variance. Reliability was substantial for the assessment of stenosis irrespective of the artery (intraclass correlation coefficient (ICC) ranging from 0.92 to 1), and good for the distal part of the artery (ICC ranging from 0.83 to 0.86) as well as for the collateral provision (ICC ranging from 0.75 to 0.94). Agreement between surgeons was good with respect to the number of bypasses to be performed (ICC = 0.88). The number of bypass per patient varied from 2.6 to 3.2 depending on the surgeon. Agreement as to whether or not to bypass was substantial for the right coronary artery (ICC = 0.92), good for the marginal artery (ICC = 0.87) and fair for the left anterior descending artery (ICC = 0.60) and the circumflex artery (ICC = 0.60). There was a higher rate of agreement concerning inferior wall motion (ICC = 0.98) than of the anterior wall motion (ICC = 0.78). Agreement was substantial for ejection fraction (ICC = 0.93), operative risk (ICC = 0.93) and the type of coronary tree (ICC = 0.85). With respect to the overall set of items, no one surgeon disagreed significantly with the rest of the group. Some disagreement regarding anatomy suitable for revascularization exists between surgeons. Surgical assessment of risk is similar. Cardiac surgeons quickly learn to assess risk in a similar manner, even though they might not always graft the same anatomic vessels or assess regional wall motion similarly.