Benoit de Varennes

Contemporary operative management of pulmonary metastases of colorectal origin.

The management of patients with metastatic disease from primary carcinoma of the colon and rectum is still controversial. To evaluate the results of resection of pulmonary metastases from patients with colorectal primaries, a retrospective study of all patients who underwent such resection was carried out at the teaching hospitals of McGill University and Université de Montréal. A total of 345 patients admitted with pulmonary metastases; 27 of them underwent pulmonary resection with the extent of the resection varying from wedge excision of the metastatic nodule to pneumonectomy. In 25 of the 27 patients the resection was considered curative. Eight of the 27 patients had resection of two metastatic lesions while the remaining 19 patients had resection of solitary lesions. The interval between resection of the primary colorectal malignancy and the resection of the metastatic lesion (disease-free interval) varied from 2 to 77 months with a median interval of 35 months. The five-year survival following resection of pulmonary metastases was 21 percent. A prolonged interval between treatment of the primary and resection of the pulmonary metastasis was associated with a longer survival. This retrospective study demonstrates that prolonged survival can be achieved following resection of pulmonary metastases from colorectal carcinoma.

Initial Results of Posterior Leaflet Extension for Severe Type IIIb Ischemic Mitral Regurgitation

Background— Management of severe ischemic mitral regurgitation remains difficult with disappointing early and intermediate-term surgical results of valve repair. Methods and Results— Forty-four patients with severe (4+) Carpentier type IIIb ischemic mitral regurgitation underwent mitral valve repair, with or without surgical revascularization, by posterior leaflet extension with a patch of bovine pericardium and a remodeling annuloplasty. Serial echocardiography was performed preoperatively, intraoperatively, and postoperatively to assess mitral valve competence. The postoperative functional status of patients was assessed. The average Parsonnet score was 38±13. Thirty-day mortality was 11%, and late mortality was 14%. Mean follow-up was 38 months. The actuarial freedom from moderate or severe recurrent mitral regurgitation was 90% at 2 years, whereas 90% of patients were in New York Heart Association class I at 2 years. Conclusion— Posterior leaflet extension with annuloplasty of the mitral valve for severe type IIIb ischemic regurgitation is a safe, effective method that provides good early and intermediate-term competence of the mitral valve and therefore good functional status.

Impact of transfusion of mediastinal shed blood on serum levels of cardiac enzymes

BACKGROUNDnInfusion of shed mediastinal blood using an autotransfusion system is a widely applied technique of blood conservation in cardiac surgery. Serial determinations of serum creatine kinase (CK), its MB isoenzyme (CK-MB), and lactate hydrogenase (LDH) levels have been used to monitor perioperative myocardial injury. We investigated the impact of postoperative autotransfused blood infusion on serum levels of these enzymes.nnnMETHODSnWe performed a retrospective analysis of postoperative serum CK, CK-MB, and LDH levels of 300 patients who had elective uncomplicated aortocoronary bypass grafting. Shed mediastinal blood samples from 26 patients were analyzed for CK, CK-MB (enzymatic activity and mass), and LDH levels before infusion.nnnRESULTSnHigh postoperative serum levels of CK and LDH were observed after infusion of autotransfused blood. Shed mediastinal blood contained extremely high levels of these enzymes, particularly from patients who had internal mammary artery dissection. There was a strong correlation (r = 0.96) between measured CK-MB enzyme activities and those calculated from the CK-MB mass units.nnnCONCLUSIONSnInfusion of autotransfused blood containing high concentrations of CK and LDH results in elevated serum levels of these enzymes. Hemolysis, frequently present in shed blood, does not interfere with the routine biochemical assays for CK and CK-MB enzyme activities. Caution should be taken when postoperative cardiac enzyme levels are used to determine myocardial injury after aortocoronary bypass grafting if autotransfusion is used as a method of blood conservation.

Reinfusion of Mediastinal Blood in CABG Patients: Impact on Homologous Transfusions and Rate of Re‐exploration

Abstract Background: Reinfusion of mediastinal shed blood after cardiac surgery has been used in some centers to reduce exposure to homologous blood transfusions. The method has not been widely applied mostly because some studies have failed to demonstrate a significant benefit. Methods: A group of 675 consecutive patients undergoing first‐time, isolated coronary artery bypass surgery (CABG) was studied. Prospective data was collected on the first 375 patients receiving autotransfusion (ATS) of mediastinal shed blood. The charts of 338 patients immediately preceding the institution of the ATS program at our institution (NO ATS group) were retrospectively reviewed. Transfusion of homologous blood products and rate of re‐exploration for bleeding were closely monitored. Results: The two groups were identical. The net blood loss was significantly less in the ATS group than in the NO ATS group (1013 ± 431 cc vs 1371 ± 631 cc, p < 0.0001). Rate of exploration for postoperative bleeding was 1.5% in the ATS group and 5.0% in the NO ATS group (p < 0.01). In the ATS group, 51.9% of patients were not exposed to any homologous blood product (vs 17.8% in the NO ATS group, p < 0.0001). The ATS patients received on the average 2.9 ± 7.2 units of blood products versus 6.4 ± 9.7 units in the NO ATS group (p < 0.0001). Conclusion: Reinfusion of mediastinal shed blood significantly reduces exposure to homologous blood transfusions and rate of re‐exploration. The ATS system reduces the number of re‐explorations for coagulopathy‐related postoperative hemorrhage.

Energy loss, a novel biomechanical parameter, correlates with aortic aneurysm size and histopathologic findings

OBJECTIVEnEnergy loss is a biomechanical parameter that represents the relative amount of energy absorbed by the aorta during the cardiac cycle. We aimed to correlate energy loss with ascending aortic aneurysm size and histopathologic findings to elucidate the pathophysiology of aneurysm complications.nnnMETHODSnAneurysmal ascending aortic specimens were obtained during surgery. Control specimens were obtained from autopsy and organ donors. Biaxial tensile tests were performed on the 4 quadrants of the aortic ring. Energy loss was calculated using the integral of the stress-strain curve during loading and unloading. It was compared with the size and the traditional biomechanical parameter, stiffness (apparent modulus of elasticity). Elastin, collagen, and mucopolysaccharide content were quantified using Movat pentachrome staining of histology slides.nnnRESULTSnA total of 41 aortas were collected (34 aneurysmal, 7 control). The aneurysms exhibited increased stiffness (P < .0001) and energy loss (P < .0001) compared with the controls. Energy loss correlated significantly with aortic size (P < .0001, r(2) = .60). A hinge point was noted at a diameter of 5.5 cm, after which energy loss increased rapidly. The relationship between energy loss and size became strongly linear once the size was indexed to the body surface area (P < .0001, r(2) = .78). Energy loss correlated with the histopathologic findings, especially the collagen/elastin ratio (P = .0002, r(2) = .49). High energy loss distinguished patients with pathologic histologic findings from others with similar diameters.nnnCONCLUSIONSnAs ascending aortas dilate, they exhibit greater energy loss that rapidly increases after 5.5 cm. This mirrors the increase in complications at this size. Energy loss correlates with imbalances in elastin and collagen composition, suggesting a measurable link between the histopathologic features and mechanical function.

Preoperative hospital length of stay as a modifiable risk factor for mediastinitis after cardiac surgery

BackgroundAs high-risk cardiac patients frequently remain within hospital while waiting for surgery, the aim of the present study was to determine the role of preoperative length of hospital stay on mediastinitis, and also, to assess contemporary risk factors for this complication.MethodsThe source population consisted of 6653 consecutive patients undergoing coronary bypass surgery, valve surgery, or both between September 2000 and September 2009 at a single tertiary care hospital. A retrospective cohort analysis was used to assess the effect of 18 preoperative variables, including length of stay, on mediastinitis.ResultsMediastinitis developed in 108 patients (1.6%) resulting in an in-hospital mortality rate of 13.9%. Independent predictors of mediastinitis included obesity (2.59, CI 1.58-4.23), COPD (2.44, CI 1.55-3.84), diabetes (2.16, CI 1.44-3.24), and impaired estimated glomerular filtration rate. Preoperative hospital stay was also found to be an independent risk factor leading to a 15% increased risk of mediastinitis per week of stay. The primary wound pathogen was coagulase negative staphylococcus (82%) followed by multi-flora isolates (49%), but was unrelated to hospital stay.ConclusionsIn addition to the traditional risk factors, prolonged preoperative hospital stay is also a significant and potentially modifiable predictor for the development of mediastinitis following cardiac surgery. All efforts should be made to minimize the delay in operating on hospitalized patients awaiting heart surgery.

Prolonged controlled mechanical ventilation in humans triggers myofibrillar contractile dysfunction and myofilament protein loss in the diaphragm

Background Prolonged controlled mechanical ventilation (CMV) in humans and experimental animals results in diaphragm fibre atrophy and injury. In animals, prolonged CMV also triggers significant declines in diaphragm myofibril contractility. In humans, the impact of prolonged CMV on myofibril contractility remains unknown. The objective of this study was to evaluate the effects of prolonged CMV on active and passive human diaphragm myofibrillar force generation and myofilament protein levels. Methods and results Diaphragm biopsies were obtained from 13 subjects undergoing cardiac surgery (control group) and 12 brain-dead organ donors (CMV group). Subjects in each group had been mechanically ventilated for 2–4 and 12–74u2005h, respectively. Specific force generation of diaphragm myofibrils was measured with atomic force cantilevers. Rates of force development (Kact), force redevelopment after a shortening protocol (Ktr) and relaxation (Krel) in fully activated myofibrils (pCa2+=4.5) were calculated to assess myosin cross-bridge kinetics. Myofilament protein levels were measured with immunoblotting and specific antibodies. Prolonged CMV significantly decreased active and passive diaphragm myofibrillar force generation, Kact, Ktr and Krel. Myosin heavy chain (slow), troponin-C, troponin-I, troponin-T, tropomyosin and titin protein levels significantly decreased in response to prolonged CMV, but no effects on α-actin, α-actinin or nebulin levels were observed. Conclusions Prolonged CMV in humans triggers significant decreases in active and passive diaphragm myofibrillar force generation. This response is mediated, in part, by impaired myosin cross-bridge kinetics and decreased myofibrillar protein levels.

Lipoprotein(a) Induces Human Aortic Valve Interstitial Cell Calcification

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Anesthesia for deep hypothermic circulatory arrest in adults: Experience with the first 50 patients

OBJECTIVEnTo evaluate the efficacy of a simple method of central nervous system (CNS) protection in patients undergoing deep hypothermic circulatory arrest (DHCA) lasting less than 30 minutes, for a variety of complex cardiovascular procedures.nnnDESIGNnA retrospective case review.nnnSETTINGnA university teaching hospital.nnnPARTICIPANTSnFifty consecutive patients (25 women, 25 men) undergoing elective or emergency cardiovascular operations requiring DHCA between August 1991 and December 1996.nnnINTERVENTIONSnPatients underwent DHCA for a variety of surgical procedures. Neurologic protection was with thiopental, ice packs to the head, and systemic core hypothermia to a nasopharyngeal temperature (NPT) of 18 degrees to 20 degrees C.nnnMEASUREMENTS AND MAIN RESULTSnThe mean duration of circulatory arrest was 18 +/- 10 minutes (range, 5 to 42 minutes). The mean NPT at time of arrest was 18.7 degrees +/- 1.7 degrees C. Three patients (6%) had gross CNS morbidity, one of whom died. The circulatory arrest times for these three patients were 8, 39, and 40 minutes. Perioperative mortality was 8% (n = 4). The circulatory arrest times for the patients who died were 12, 13, 23, and 39 minutes.nnnCONCLUSIONnThe anesthetic management of DHCA described is simple, effective, and safe, and can be performed in any institution that performs cardiac surgery.

Randomised trial of mitral valve repair with leaflet resection versus leaflet preservation on functional mitral stenosis (The CAMRA CardioLink-2 Trial)

Background The gold-standard treatment of severe mitral regurgitation (MR) due to degenerative disease is valve repair, which is surgically performed with either a leaflet resection or leaflet preservation approach. Recent data suggest that functional mitral stenosis (MS) may occur following valve repair using a leaflet resection strategy, which adversely affects patient prognosis. A randomised comparison of these two approaches to mitral repair on functional MS has not been conducted. Methods and analysis This is a prospective, multicentre randomised controlled trial designed to test the hypothesis that leaflet preservation leads to better preservation of mitral valve geometry, and therefore, will be superior to leaflet resection for the primary outcome of functional MS as assessed by 12-month mean mitral valve gradient at peak exercise. Eighty-eight patients with posterior leaflet prolapse will be randomised intraoperatively once deemed by the operating surgeon to feasibly undergo mitral repair using either a leaflet resection or leaflet preservation approach. Secondary end points include comparison of repair strategies with regard to mitral valve orifice area, leaflet coaptation height, 6u2009min walk test and a composite major adverse event end point consisting of recurrent MR ≥2+, death or hospital readmission for congestive heart failure within 12u2009months of surgery. Ethics and dissemination Institutional ethics approval has been obtained from all enrolling sites. Overall, there remains clinical equipoise regarding the mitral valve repair strategy that is associated with the least likelihood of functional MS. This trial hopes to introduce high-quality evidence to help surgical decision making in this context. Trial registration number NCT02552771.