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Difference between endothelium-dependent relaxation in arterial and in venous coronary bypass grafts.

Both the internal mammary artery and the saphenous vein are used to construct coronary-artery bypass grafts. We hypothesized that the release or production of endothelium-derived relaxing factor, which regulates blood flow and inhibits platelet function, may differ in venous and arterial grafts. We therefore studied endothelium-dependent relaxation in internal mammary arteries, internal mammary veins, and saphenous veins obtained from 58 patients undergoing coronary bypass surgery. Vascular rings with and without endothelium were suspended in organ chambers, and isometric tension was recorded. Acetylcholine (10(-8) to 10(-4) M), thrombin (1 U per milliliter), and adenosine diphosphate (10(-7) to 10(-4) M) evoked potent endothelium-dependent relaxation in the mammary artery but weak response in the saphenous vein (P less than 0.005; n = 6 to 27). In the mammary artery, relaxation was greatest in response to acetylcholine (86 +/- 4 percent reduction in norepinephrine-induced tension), followed by thrombin (44 +/- 7 percent) and adenosine diphosphate (39 +/- 8 percent). In the saphenous and mammary veins, relaxation was less than 25 percent. Relaxation was unaffected by indomethacin but was inhibited by methylene blue and hemoglobin (P less than 0.005 and 0.01, respectively), which suggests that endothelium-derived relaxing factor was the mediator. Endothelium-independent relaxation in response to sodium nitroprusside was similar in arteries and veins. We conclude that endothelium-dependent relaxation is greater in the mammary artery than in the saphenous vein. The possibility that this contributes to the higher patency rate among arterial grafts than among venous grafts will require further study.

Acute traumatic aortic rupture: early stent-graft repair

OBJECTIVE Prospective evaluation of early stent-graft repair of acute traumatic aortic rupture. METHODS Twelve patients with acute traumatic aortic rupture of the descending aorta, out of a series of 337 endovascular aortic procedures, were treated by implantation of self-expanding stent-grafts. The procedures were performed within a mean post-injury time-period of 5+/-7 days (median: 1 day). The feasibility of stent-grafting was assessed by CT scanning and echography. Implantation was performed under local (n=6), or general anesthesia (n=6) if patients were already intubated (n=5) or required a common iliac artery access (n=1). RESULTS The immediate technical success rate was 100%. There were no post-procedure complications in all but one patient, who died 12 h postoperatively (8% mortality). Complete sealing of the aortic rupture in the remaining 11 patients was confirmed by postoperative CT scans. There were no intervention-related morbidity or mortality during the mean follow-up of 17 months. One patient with peri-graft leakage was successfully repaired with an additional stent-graft 12 months postoperatively. CONCLUSION Non-delayed or early stent-grafting in acute traumatic rupture of the descending aorta is feasible. This technique seems to be a valuable option, in particular when associated lesions may interfere with the surgical outcome. Immediate post-procedural CT scanning and/or echography should be performed, in order to rule out residual leakage.

Different mobilization of calcium in endothelin-1-induced contractions in human arteries and veins : effects of calcium antagonists

Summary We studied the role of extra-and intracellular Ca2+ in endothelin-1 -induced contractions of the isolated human internal mammary artery and vein. Veins were more sensitive to the peptide than arteries (concentration shift: 3.2-fold; n = 4–10, p < 0.05). The Ca2+ antagonists darodipine, verapamil, and diltiazem (10-7-10-6 M) did not prevent the response to endothelin-1 in both vessels. In contrast, darodipine (10-8 −10-6 M), added after the contraction had developed, partially reversed the response in the artery (26 ± 7%) and particularly in the vein (67 ± 5%; n = 4, p < 0.005 compared to the artery). Removal of extracellular Ca2+ reduced the contractions to endothelin-1 (10-8 M) in the artery (control: 89 ± 4% of 100 m M KCl; Ca2+ -free: 68 ± 4% n = 4–6, p < 0.01), but not in the vein except at low concentrations (10-9 M) of the peptide. After removal of intracellular Ca2+ with caffeine in the artery, endothelin-1 still evoked a contraction (17 ± 3%, n = 3; p < 0.005 vs. control), while in the vein the response was abolished. Thus, mobilization of Ca2+ during endothelin-1-induced contractions differs in the human internal mammary artery and vein. In the artery, the contraction depends on extracellular Ca2+, intracellular caffeine-sensitive Ca2+ stores, and a caffeine-insensitive component, while in veins, mobilization of intracellular Ca2+ is most important. Ca2+ antagonists do not prevent, but partially reverse, endothelin-1-induced contractions indicating that voltage-operated Ca2+ channels do not initiate but contribute to the maintenance of the response.

The clinical significance of an elevated postoperative glucose value in nondiabetic patients after colorectal surgery: evidence for the need for tight glucose control?

Objectives: To evaluate the significance of hyperglycemia in patients without a preoperative diagnosis of diabetes undergoing elective colorectal surgery. Methods: Preoperative and all postoperative blood glucose measurements were retrieved for 2628 consecutive patients undergoing elective colorectal resection within 2 years at 1 center. Nondiabetic patients were identified as those without a preoperative diagnosis of diabetes and/or based on HbA1C levels. The association between any elevated postoperative random glucose value (hyperglycemia: >125 mg/dL) and level of elevation (>125 mg/dL or >200 mg/dL) within 72 hours of surgery in nondiabetic patients with 30-day mortality and infectious and noninfectious complications was assessed. Results: Evaluation of 16,404 postoperative glucose measurements for all 2447 nondiabetic patients who underwent surgery in 2010 and 2011 revealed that 66.7% patients experienced hyperglycemia. Degree of hyperglycemia correlated with increasing American Society of Anesthesiologists class and surgical severity (blood loss). Hyperglycemia was associated with infectious and noninfectious complications and mortality, the rates of these complications increasing parallel to the degree of hyperglycemia. Hyperglycemia was independently associated with septic complications (P = 0.024). Conclusions: Postoperative hyperglycemia is frequent after elective colorectal surgery in nondiabetic patients. Even a single postoperative elevated glucose value is adversely associated with morbidity and mortality; this risk is related to the degree of glucose elevation. These findings strongly support monitoring of glucose values and early consideration of management strategies for glycemic control after surgery even in nondiabetic patients.

Clinical evaluation of duraflo II heparin treated extracorporeal circulation circuits (2nd version): The European working group on heparin coated extracorporeal circulation circuits

OBJECTIVES To evaluate whether the application of heparin treated circuits for elective coronary artery surgery improves postoperative recovery, a European multicenter randomised clinical trial was carried out. METHODS In 11 European heart centers, 805 low-risk patients underwent cardiopulmonary bypass (CPB) with either an untreated circuit (n = 407) or an identical but heparin treated circuit (n = 398, Duraflo II). RESULTS Significant differences were found among participating centers with respect to patient characteristics, blood handling procedures and postoperative care. The use of heparin treated circuits revealed no overall changes in blood loss, blood use, time on ventilator, occurrence of adverse events, morbidity, mortality, and intensive care stay. These results did not change after adjustment for centers and (other) prognostic factors as analysed with logistic regression. In both groups no clinical or technical (patient or device related) side effects were reported. Because female gender and aortic cross clamp time appeared as prognostic factors in the logistic regression analysis, a subgroup analysis with these variables was performed. In a subpopulation of females (n = 99), those receiving heparin treated circuits needed less blood products, had a lower incidence of rhythm disturbances and were extubated earlier than controls. In another subgroup of patients with aortic cross clamp time exceeding 60 min (n = 197), the amount of patients requiring prolonged intensive care treatment (> 24 h) was significantly lower when they received heparin treated circuits versus controls. CONCLUSION These findings suggest that improved recovery can be expected with heparin treated circuits in specific higher risk patient populations (e.g. females) and when prolonged aortic cross clamp time is anticipated. Further investigations are recommended to analyses the clinical benefit of heparin treated circuits in studies with patients in different well defined risk categories and under better standardised circumstances.

The internal mammary artery malperfusion syndrome: incidence, treatment and angiographic verification.

Internal mammary artery (IMA) malperfusion syndrome is caused by an acute imbalance between myocardial demand and nutritional support through the mammary artery. In a consecutive series of 2326 isolated myocardial revascularizations-with at least one IMA to the left anterior descending branch (LAD) in 91.3% (2125/2326)-we identified 45 patients (1.9%) with a perioperative course suggesting IMA malperfusion syndrome. Additional saphenous vein graft to the distal segment of the LAD was performed during normothermic ventricular fibrillation in all patients. Hospital mortality was 4.4% (2/45), intra-aortic balloon pumping was required in 15.5% (7/45) and anterior myocardial infarction occurred in 28.8% (13/45). Coronary angiography was performed in all survivors between 3 and 24 months postoperatively. Wide patent IMA graft and patent saphenous vein graft were observed in 56% (24/43), narrowed but patent IMA graft and patent vein graft in 35% (15/43), while patent vein graft and not visualized IMA in 7% (3/43); in one patient with severely diseased peripheral LAD, no flow could be demonstrated in the IMA graft or in the additional vein graft (1/43, 2.4%). No major differences were found between early and late coronary angiography in these patients. Additional vein graft to distal LAD is the treatment of choice in acute IMA malperfusion syndrome. Despite patent vein graft with superior blood flow, early and late postoperative IMA flow to LAD is maintained in the majority of patients.

Evolution of antimicrobial prophylaxis in cardiovascular surgery

OBJECTIVE To examine the optimal duration of antibiotic prophylaxis in major cardiovascular surgery. MTHODSs: In the past 15 years, four prospective randomized, controlled studies, conducted by the same group of authors, compared seven prophylactic antimicrobial regimens in 2970 patients undergoing major cardiovascular surgery. In 1980/81, a 4-day cefazolin (CFZ) prophylaxis was compared with a 2-day cefuroxime (CFX) administration (n=566). In 1982/83, a 2-day CFX prophylaxis was compared with a two shot ceftriaxone (CRO) prophylaxis (n=512). In 1984/87, a 1-day CFZ prophylaxis was compared with a single shot prophylaxis of CRO (n=883). In 1994/1995, a 4 day combination of amoxicillin (AM) and netilmicin (NET) prophylaxis was compared with a single shot prophylaxis of CFX (n=1009). RESULTS Total infection rate varied between 4.5 and 5.7%, despite different antimicrobial regimen used and their varying duration. Wound infection rate was 1.1% (range 0.4-2.5%), sepsis rate was 0.8% (range 0.4-1.6%), pneumonia rate 2% (0.7-2.9%), urinary tract infection rate 0.4% (range 0-1.4%), and central venous catheter-related infection rate was 0.4% (0-1%). The 30-day mortality rate was 1.3% (range 0.4-2%). All these differences were not statistically significant. CONCLUSIONS A low infection rate (range 4.5-5.7%) occurred despite changes in duration of various prophylactic antibiotic regimen with cephalosporins of first, second or third generation. As a single shot prophylaxis could nowadays successfully be used in cardiovascular surgery, no postoperative antibiotics should be used, unless an intraoperative or a postoperative infection is documented or in presence of major perioperative complications.

Predictors of complications in acute type B aortic dissection

OBJECTIVES Medical treatment is generally advocated for patients with acute type B aortic dissection without complications. The objective of this retrospective analysis was to determine whether there are any initial findings that can help predict the long-term course of the disease. METHODS Case records of the 130 patients treated for type B aortic dissection between 1988 and 1997 were reviewed; 41 (31%) were operated on in the acute phase (<14 days), 31 (24%) were operated on in the chronic phase and 58 (45%) were treated medically. RESULTS Overall acute mortality was 10.8%; 22% for patients operated on in the early phase and 5.6% for medically treated patients. Age (P=0.002), persistent pain (P=0.01) and malperfusion (P=0.001) were significant independent predictors of the need for surgery. Paraplegia/para paresis (P=0.0001), leg ischaemia (P=0.003), pleural effusion (P=0.003), rupture (P=0.0001), shock (P=0.0001), age (P=0.003), cardiac failure (P=0.002) and aortic diameter >4.5 cm (P=0.002) were significant predictors of poor survival. Age and shock also emerged as independent risk factors. Patients without malperfusion (P=0.0001), pleural effusion (P=0.003), rupture (P=0.0001) and shock (P=0.0001) had a significantly better event-free survival (freedom from repeat surgery and death). The actuarial survival rate for high-risk patients (malperfusion, rupture, shock) was 62% at 1 year and 40% at 5 years; the corresponding values for low-risk patients were 94 and 84%, respectively. CONCLUSIONS Rupture, shock and malperfusion are significant predictors of poor survival in patients with acute type B aortic dissection.

Obese trauma patients are at increased risk of early hypovolemic shock: a retrospective cohort analysis of 1,084 severely injured patients.

IntroductionMorbid obesity and its consequences are considered risk factors for adverse outcome in trauma, although the pathophysiologic mechanisms are incompletely understood. The aim of this study was to compare initial resuscitation, treatment, and short-term outcome of severely injured patients by body mass index (BMI).MethodsA total of 1,084 severely injured patients with an injury severity score of 16 or greater were enrolled between 1996 and 2009 and grouped according to BMI. Their course of treatment and in-hospital outcome were analyzed by univariate and multivariate comparison.ResultsOf these patients, 603 (55.6%) were of normal weight with a BMI between 18.5 and 24.9, 361 (33.3%) had BMI values between 25 and 29.9, and 90 patients (8.3%) were obese (BMI ≥ 30). Thirty patients (2.8%) had BMI levels below 18.5. All groups were comparable with respect to injury severity, initial resuscitation, and time to ICU admission. There was a tendency towards higher mortality in obese patients (mortality 24.4%) and also overweight patients (mortality 18.8%) when compared with patients with a normal BMI (mortality 16.6%). Obese patients showed the highest mortality on day 0 (8.9% vs. 2.8% in the normal-weight group, P = 0.023), mostly due to persistent shock (6.7%). When corrected for BMI, obese patients are provided significantly lower volumes of intravenous fluids during the initial resuscitation period.ConclusionIn contrast to the mostly American literature, only a low percentage of trauma patients at a European trauma center are obese. These patients are at risk of higher mortality from persistent hemorrhagic shock in the initial phase after trauma, which may potentially be related to relative hypovolemia during the resuscitation period. In the later course of treatment, no significant differences exist with respect to specific complications, hospital stay, or in-hospital mortality.

Laparoscopic cholecystectomy as a teaching operation: comparison of outcome between residents and attending surgeons in 1,747 patients

PurposeStandardized surgical training is increasingly confronted with the public demand for high quality of surgical care in modern teaching hospitals. The aim of this study was to compare the results of laparoscopic cholecystectomy (LC) performed by resident surgeons (RS) and attending surgeons (AS).MethodsIn this retrospective review of prospectively collected data 1,747 LC were performed in a community hospital between 1999 and 2009. Seven hundred seventy operations were performed by RS. Parameters analysed included the duration of operation and length of hospital stay, intraoperative complications, 30-day morbidity and mortality.ResultsDuration of operation was 88 (25–245) min for RS vs. 75 (30–190) min by AS (p = 0.001). Elective operations were shorter when performed by AS (70 (30–190) [AS] vs. 85 (25–240) [RS] min, p = 0.001). Length of hospital stay was shorter in patients treated by RS (4 (1–49) days [RS] vs. 5 (1–83) days [AS], p = 0.1). Intraoperative complications showed no differences between the groups (1.0% [RS] vs. 1.3% [AS], p = 0.6), whereas 30-day morbidity was lower in patients treated by RS (3.8% [RS] vs. 6.2% [AS], p = 0.02). Overall mortality was 0.6% and independent of surgical expertise (0.5% [RS] vs. 0.8% [AS], p = 0.5).ConclusionsProvided adequate training, supervision and patient selection, surgical residents are able to perform LC with results comparable to those of experienced surgeons.