Methemoglobin as a marker of acute anemic stress in cardiac surgery.

Biological evidence supports plasma methemoglobin as a biomarker for anemia-induced tissue hypoxia. In this translational planned substudy of the multinational randomized controlled transfusion thresholds in cardiac surgery (TRICS-III) trial, which included adults undergoing cardiac surgery requiring cardiopulmonary bypass with a moderate-to-high risk of death, we investigated the relationship between perioperative hemoglobin concentration (Hb) and methemoglobin; and evaluated its association with postoperative outcomes. The primary endpoint was a composite of death, myocardial infarction, stroke, and severe acute kidney injury at 28 days. We observe weak non-linear associations between decreasing Hb and increasing methemoglobin, which were strongest in magnitude at the post-surgical time point. Increased levels of post-surgical methemoglobin were associated with a trend toward an elevated risk for stroke and exploratory neurological outcomes. Our generalizable study demonstrates post-surgical methemoglobin may be a marker of anemia-induced organ injury/dysfunction, and may have utility for guiding personalized approaches to anemia management. Clinicaltrials.gov registration NCT02042898.

Mechanical Versus Bioprosthetic Valve Replacement in the Tricuspid Valve Position: A Systematic Review and Meta-Analysis.

BACKGROUND: The ideal prosthesis for tricuspid valve replacement (TVR) continues to be debated. There are few published data comparing mechanical and bioprosthetic valves, and all are retrospective studies with relatively small sample sizes. AIM: This study was conducted to compare mechanical and bioprosthetic valves for TVR. METHOD: A literature search of six databases (PubMed, EMBASE, Ovid, ScienceDirect, JSTOR, and Wiley Blackwell's online library) was performed with the keywords "tricuspid valve disease, tricuspid valve replacement and (bioprosthetic or mechanical)". Primary outcomes were hospital mortality, long-term survival, tricuspid valve reoperation, valve failure, thrombosis, and thrombo-embolism. Risk ratio (RR) was used to compare dichotomous parameters and time-to-event outcomes. "Survival and re-interventions" were pooled using a meta-analysis of hazard ratios (HR). Publication bias was accessed using a funnel plot. RESULTS: A total of 23 retrospective studies involving 945 mechanical and 1,332 biological tricuspid prostheses were included. The studies were published between January 2002 and September 2019. Hospital mortality (30-day mortality) did not differ between groups (RR, 0.83; 95% confidence interval [CI], 0.66-1.05; p=0.12). Long-term survival was evaluated in 15 studies, and it was not significantly different between patients with mechanical compared with those with bioprosthetic valves (pooled HR, 0.97; 95% CI, 0.61-1.54; p=0.88). Freedom from tricuspid valve reoperation was assessed in eight studies, and no difference was found between the groups (pooled HR, 1.03; 95% CI, 0.63-1.69; p=0.89). Valve failure in the 5-year postoperative period was evaluated by seven studies, and there was no statistically significant difference between the two groups (pooled RR, 1.33; 95% CI, 0.42-4.27; p=0.63). CONCLUSIONS: The results of this meta-analysis suggest an equal risk of 30-day and late mortality, reoperation, and 5-year valve failure in patients with mechanical versus biological TVR. The choice of the prosthesis in the tricuspid position should depend mainly on the patient's risk factors and no superiority of one prosthesis over the other in this position.

Should Moderate Functional Tricuspid Regurgitation Be Repaired During Surgery for Rheumatic Mitral Valve Disease?

BACKGROUND: Surgical repair of concomitant functional moderate tricuspid valve (TV) regurgitation at the time of mitral valve (MV) surgery remains controversial. AIM: The objective of this study was to evaluate the outcomes of concomitant repair of functional moderate tricuspid regurgitation (TR) during MV surgery for rheumatic valve disease. METHOD: From 1998 to 2016, 1,240 patients had rheumatic MV disease associated with moderate functional TR: 974 patients had MV surgery and concomitant TV repair (group 1) and 266 patients had MV surgery alone (group 2). Study endpoints were operative outcomes, rehospitalisation for congestive heart failure (CHF), and TV reintervention. Propensity score matching identified 192 well-matched pairs for outcomes comparison. RESULTS: Patients who had concomitant TV repair were younger (p=0.02) and there were fewer diabetics (p=0.015). In matched patients, low cardiac output was significantly higher in group 2 (p=0.044) and there was no difference in ventilation time, intensive care unit stay, cardiopulmonary bypass, and ischaemic times (p=0.480, p=0.797, p=0.232, and p=0.550, respectively) between groups. Patients in group 2 required more TV reintervention (1 vs 35 in group 1 and 2, respectively; p=0.004) and rehospitalisation for CHF (5 vs 40 in group 1 and 2, respectively; p<0.001). CONCLUSIONS: Concomitant TV repair for moderate TR in patients undergoing rheumatic MV surgery was not associated with increased operative risk. Postoperative low cardiac output syndrome and the risk of late TV reinterventions and rehospitalisation for CHF were lower with TV repair. Concomitant repair of the moderate TV regurgitation maybe beneficial for patients undergoing rheumatic MV surgery.

Can posterior pericardiotomy reduce the incidence of postoperative atrial fibrillation after coronary artery bypass grafting?†.

OBJECTIVES: Atrial fibrillation (AF) is a common complication that increases the morbidity after open heart surgery. The pathophysiology is uncertain, and its prevention remains suboptimal. The aim of this study was to assess the efficiency of posterior pericardiotomy in decreasing the incidence of pericardial effusion and postoperative AF. METHODS: This multicentre randomized prospective study included 200 patients who underwent open heart surgery; coronary artery bypass grafting procedure between June 2010 and May 2012. A posterior pericardiotomy incision was done in Group I (n = 100). A longitudinal incision, 4-cm long and 2-cm width, was made parallel and posterior to the left phrenic nerve, extending from the left inferior pulmonary vein to the diaphragm. Group II constituted the control group (n = 100). Postoperative pericardial effusion was assessed by echocardiography and rhythm follow-up was monitored daily. RESULTS: The incidence of postoperative AF was significantly lower in the posterior pericardiotomy group than in the control group (13 vs 30%, P = 0.01). The number of patients with remarkable postoperative pericardial effusion was significantly lower in the posterior pericardiotomy group (15 vs 50 patients, P = 0.04). Tamponade developed in 3 patients in Group II (P = 0.07). There was a significantly higher incidence of chest drainage in the posterior pericardiotomy group than in the control group (1041 ± 549 vs 911 ± 122 ml; P = 0.04). There was no significant difference between the two groups regarding hospital stay (8 vs 9 days, P > 0.05). CONCLUSIONS: Posterior pericardiotomy is a simple, safe and effective method for reducing the incidence of postoperative pericardial effusion and related atrial fibrillation by improving pericardial drainage after coronary artery bypass grafting.

Sternal plate fixation for sternal wound reconstruction: initial experience (retrospective study).

BACKGROUND: Median sternotomy infection and bony nonunion are two commonly described complications which occur in 0.4-5.1% of cardiac procedures. Although relatively infrequent, these complications can lead to significant morbidity and mortality. The aim of this retrospective study is to evaluate the initial experience of a transverse plate fixation system following wound complications associated with sternal dehiscence with or without infection following cardiac surgery. METHODS: A retrospective chart review of 40 consecutive patients who required sternal wound reconstruction post sternotomy was performed. Soft tissue debridement with removal of all compromised tissue was performed. Sternal debridement was carried using ronguers to healthy bleeding bone. All patients underwent sternal fixation using three rib plates combined with a single manubrial plate (Titanium Sternal Fixation System®, Synthes). Incisions were closed in a layered fashion with the pectoral muscles being advanced to the midline. Data were expressed as mean±SD, Median (range) or number (%). Statistical analyses were made by using Excel 2003 for Windows (Microsoft, Redmond, WA, USA). RESULTS: There were 40 consecutive patients, 31 males and 9 females. Twenty two patients (55%) were diagnosed with sternal dehiscence alone and 18 patients (45%) with associated wound discharge. Thirty eight patients went on to heal their wounds. Two patients developed recurrent wound infection and required VAC therapy. Both were immunocompromised. Median post-op ICU stay was one day with the median hospital stay of 18 days after plating. CONCLUSION: Sternal plating appears to be an effective option for the treatment of sternal wound dehiscence associated with sternal instability. Long-term follow-up and further larger studies are needed to address the indications, benefits and complications of sternal plating.

Complete mapping of the tricuspid valve apparatus using three-dimensional sonomicrometry.

OBJECTIVE: Many surgeons consider the tricuspid valve to be a second-class structure. Our objective was to determine the normal anatomy and dynamic characteristics of the tricuspid valve apparatus in vivo and to discern whether this would aid the design of a tricuspid valve annuloplasty ring model. METHODS: Sixteen sonomicrometry crystals were placed around the tricuspid annulus, at the bases and tips of the papillary muscles, the free edges of the leaflets, and the right ventricular apex during cardiopulmonary bypass in 5 anesthetized York Hampshire pigs. Animals were studied after weaning of cardiopulmonary bypass on 10 cardiac cycles of normal hemodynamics. RESULTS: Sonomicrometry array localizations demonstrate the multiplanar shape of the tricuspid annulus. The tricuspid annulus reaches its maximum area (97.9 ± 25.4 mm(2)) at the end of diastole and its minimum area (77.3 ± 22.5 mm(2)) at the end of systole, and increases again in early diastole. Papillary muscles shorten by 0.8 to 1.5 mm (11.2%) in systole, and chordae tendineae straighten by 0.8 to 1.7 mm (11.4%) in systole. CONCLUSIONS: The shape of the tricuspid annulus is a multiplanar 3-dimensional one with its highest point at the anteroseptal commissure and its lowest point at the posteroseptal commissure, and the anteroposterior commissure is in a middle plane in between. The tricuspid annulus area reaches its maximum during diastole and its minimum during systole. The papillary muscles contract by the same amount of chordal straightening. The optimal tricuspid annuloplasty ring may be a multiplanar 3-dimensional one that mimics the normal tricuspid annulus.

Are chest compressions safe for the patient reconstructed with sternal plates? Evaluating the safety of cardiopulmonary resuscitation using a human cadaveric model.

BACKGROUND: Plate and screw fixation is a recent addition to the sternal wound treatment armamentarium. Patients undergoing cardiac and major vascular surgery have a higher risk of postoperative arrest than other elective patients. Those who undergo sternotomy for either cardiac or major vascular procedures are at a higher risk of postoperative arrest. Sternal plate design allows quick access to the mediastinum facilitating open cardiac massage, but chest compressions are the mainstay of re-establishing cardiac output in the event of arrest. The response of sternal plates and the chest wall to compressions when plated has not been studied. The safety of performing this maneuver is unknown. This study intends to demonstrate compressions are safe after sternal plating. METHODS: We investigated the effect of chest compressions on the plated sternum using a human cadaveric model. Cadavers were plated, an arrest was simulated, and an experienced physician performed a simulated resuscitation. Intrathoracic pressure was monitored throughout to ensure the plates encountered an appropriate degree of force. The hardware and viscera were evaluated for failure and trauma respectively. RESULTS: No hardware failure or obvious visceral trauma was observed. Rib fractures beyond the boundaries of the plates were noted but the incidence was comparable to control and to the fracture incidence after resuscitation previously cited in the literature. CONCLUSIONS: From this work we believe chest compressions are safe for the patient with sternal plates when proper plating technique is used. We advocate the use of this life-saving maneuver as part of an ACLS resuscitation in the event of an arrest for rapidly re-establishing circulation.

Impact of clopidogrel use on mortality and major bleeding in patients undergoing coronary artery bypass surgery.

Patients who received clopidogrel prior to coronary bypass surgery are at increased risk for bleeding that must be balanced with risk of ongoing ischemia if coronary artery bypass grafting is delayed. This study aimed to evaluate the impact of clopidogrel on mortality and major bleeding in patients undergoing urgent coronary bypass surgery. We reviewed 451 consecutive patients who underwent urgent isolated coronary bypass surgery; 262 had not received clopidogrel, whereas 189 received clopidogrel < or = 5 days preoperative. The primary endpoint was in-hospital death, massive transfusion or massive blood loss. Patient characteristics were almost similar between groups. There was no difference in in-hospital death or massive bleeding indices between groups (clopidogrel: 7% vs. no clopidogrel: 6%, P = 0.9). No difference was observed even after adjusting for the date of stopping clopidogrel preoperatively. Multivariate regression analysis showed that clopidogrel or the duration it was stopped preoperatively, did not predict adverse outcomes. Significant independent predictors included preoperative renal dysfunction, hemoglobin level and peripheral vascular disease. clopidogrel, or the time it was stopped prior to surgery, was not a risk factor for in-hospital death, massive bleeding, or other poor early outcomes in patients undergoing urgent coronary artery bypass surgery.

Can local application of Tranexamic acid reduce post-coronary bypass surgery blood loss? A randomized controlled trial.

BACKGROUND: Diffuse microvascular bleeding remains a common problem after cardiac procedures. Systemic use of antifibrinolytic reduces the postoperative blood loss. The purpose of this study was to examine the effectiveness of local application of tranexamic acid to reduce blood loss after coronary artery bypass grafting (CABG). METHODS: Thirty eight patients scheduled for primary isolated coronary artery bypass grafting were included in this double blind, prospective, randomized, placebo controlled study. Tranexamic acid (TA) group (19 patients) received 1 gram of TA diluted in 100 ml normal saline. Placebo group (19 patients) received 100 ml of normal saline only. The solution was purred in the pericardial and mediastinal cavities. RESULTS: Both groups were comparable in their baseline demographic and surgical characteristics. During the first 24 hours post-operatively, cumulative blood loss was significantly less in TA group (median of 626 ml) compared to Placebo group (median of 1040 ml) (P = 0.04). There was no significant difference in the post-op Packed RBCs transfusion between both groups (median of one unit in each) (P = 0.82). Significant less platelets transfusion required in TA group (median zero unit) than in placebo group (median 2 units) (P = 0.03). Apart from re-exploration for excessive surgical bleeding in one patient in TA group, no difference was found in morbidity or mortality between both groups. CONCLUSION: Topical application of tranexamic acid in patients undergoing primary coronary artery bypass grafting led to a significant reduction in postoperative blood loss without adding extra risk to the patient.

Sternal plating for primary and secondary sternal closure; can it improve sternal stability?

BACKGROUND: Sternal instability with mediastinitis is a very serious complication after median sternotomy. Biomechanical studies have suggested superiority of rigid plate fixation over wire cerclage for sternal fixation. This study tests the hypothesis that sternal closure stability can be improved by adding plate fixation in a human cadaver model. METHODS: Midline sternotomy was performed in 18 human cadavers. Four sternal closure techniques were tested: (1) approximation with six interrupted steel wires; (2) approximation with six interrupted cables; (3) closure 1 (wires) or 2 (cables) reinforced with a transverse sternal plate at the sixth rib; (4) Closure using 4 sternal plates alone. Intrathoracic pressure was increased in all techniques while sternal separation was measured by three pairs of sonomicrometry crystals fixed at the upper, middle and lower parts of the sternum until 2.0 mm separation was detected. Differences in displacement pressures were analyzed using repeated measures ANOVA and Regression Coefficients. RESULTS: Intrathoracic pressure required to cause 2.0 mm separation increased significantly from 183.3 +/- 123.9 to 301.4 +/- 204.5 in wires/cables alone vs. wires/cables plus one plate respectively, and to 355.0 +/- 210.4 in the 4 plates group (p < 0.05). Regression Coefficients (95% CI) were 120 (47-194) and 142 (66-219) respectively for the plate groups. CONCLUSION: Transverse sternal plating with 1 or 4 plates significantly improves sternal stability closure in human cadaver model. Adding a single sternal plate to primary closure improves the strength of sternal closure with traditional wiring potentially reducing the risk of sternal dehiscence and could be considered in high risk patients.

Predictors of packed red cell transfusion after isolated primary coronary artery bypass grafting--the experience of a single cardiac center: a prospective observational study.

BACKGROUND: Preoperative patients' characteristics can predict the need for perioperative blood component transfusion in cardiac surgical operations. The aim of this prospective observational study is to identify perioperative patient characteristics predicting the need for allogeneic packed red blood cell (PRBC) transfusion in isolated primary coronary artery bypass grafting (CABG) operations. PATIENTS AND METHODS: 105 patients undergoing isolated, first-time CABG were reviewed for their preoperative variables and followed for intraoperative and postoperative data. Patients were 97 males and 8 females, with mean age 58.28 +/- 10.97 years. Regression logistic analysis was used for identifying the strongest perioperative predictors of PRBC transfusion. RESULTS: PRBC transfusion was used in 71 patients (67.6%); 35 patients (33.3%) needed > 2 units and 14 (13.3%) of these needed > 4 units. Univariate analysis identified female gender, age > 65 years, body weight < or = 70 Kg, BSA < or = 1.75 m(2), BMI < or = 25, preoperative hemoglobin < or = 13 gm/dL, preoperative hematocrit < or = 40%, serum creatinine > 100 micromol/L, Euro SCORE (standard/logistic) > 2, use of CPB, radial artery use, higher number of distal anastomoses, and postoperative chest tube drainage > 1000 mL as significant predictors. The strongest predictors using multivariate analysis were CPB use, hematocrit, body weight, and serum creatinine. CONCLUSION: The predictors of PRBC transfusion after primary isolated CABG are use of CPB, hematocrit < or = 40%, weight < or = 70 Kg, and serum creatinine > 100 micromol/L. This leads to better utilization of blood bank resources and cost-efficient targeted use of expensive blood conservation modalities.

Harvesting of the radial artery for coronary artery bypass grafting: comparison of ultrasonic harmonic scalpel dissector with the conventional technique.

OBJECTIVES: Use of the radial artery for coronary artery bypass grafting is getting more popular. We started routine use of the ultrasonic dissecting scalpel in harvesting radial arteries aiming to minimize harvesting time, improve graft quality, and reduce wound complications. METHODS: Radial artery harvesting technique using harmonic scalpel (HS; 43 patients) was compared with the conventional technique (Hemostatic clips and scissors; 53 patients). To avoid spasm, the radial artery was not skeletonized and papaverine was used to irrigate radial artery routinely in all patients. RESULTS: Compared to the conventional technique, radial artery harvesting using the HS has a significantly shorter harvesting time (25 minutes vs. 50 minutes, p < 0.001) and required a significantly smaller number of hemostatic clips (3 vs. 40, p < 0.001). In situ free blood flow was significantly higher in HS group (80 mL/min vs. 40 mL/min, p < 0.001). There was no forearm wound infection in the HS group. There was no graft failure, reoperation for bleeding, or hand ischemia with the use of either technique. CONCLUSION: Harvesting the radial artery using the HS is less time consuming and decreased the use of hemostatic clips rather atraumatic with good quality graft.

Comparison of pulmonary gas exchange in OPCAB versus conventional CABG.

BACKGROUND: Cardiopulmonary bypass has been implicated as a cause of acute lung injury in cardiac surgical patients. This could be avoided with off-pump coronary artery bypass surgery. Aim. To ascertain the possible benefit of OPCAB surgery on pulmonary gas exchange. METHODS: We randomized 75 consecutive patients (mean age 57 years) into two groups: Group 1 off-pump coronary artery bypass surgery (OPCAB), n=37, Group 2 conventional coronary artery bypass grafting (con CABG), n=38. Alveolar-arterial oxygen difference (A-aO(2) difference) was calculated pre-operatively, then 2 and 4h post-operatively. PaO(2)/FiO(2) ratio and respiratory index (RI) were calculated 2 and 4h post-operatively. RESULTS: Alveolar-arterial O(2) gradient sharply increased in the immediate post-operative period, from 27mmHg pre-operatively, to 227mmHg 2h post-operatively, then declined to 152mmHg 4h post-operatively. PaO(2)/FiO(2) ratio and RI also showed severe worsening 2h post-operatively, with marked improvement at 4h. The pattern of physiological deterioration of gas exchange was similar in both the groups. CONCLUSION: In terms of pulmonary gas exchange, similar degree of deterioration is noticed in CABG patients with or without cardiopulmonary bypass. OPCAB seems to provide no physiological benefit of gas exchange at the alveolar capillary membrane when compared to conventional CABG.

Predictive value of EuroSCORE and Parsonnet scoring in Saudi population.

BACKGROUND: There is no previously published report on the applicability of risk stratification systems to adult cardiac patients in Saudi Arabia. AIM: We have tried to verify the predictive value of Parsonnet and EuroSCORE in Saudi patients. METHODS: Data of 194 consecutive adult patients operated in our unit over the period of last few years, was obtained retrospectively. There were no omissions. The EuroSCORE and Parsonnet scores were estimated for all the patients and compared with the observed mortality, morbidity and hospital length of stay (LOS). Calibration was determined by Hosmer-Lemeshow goodness of fit statistics (HL) while discrimination was assessed by using receiver operating characteristic (ROC) curve. RESULTS: For prediction of "mortality" the area under ROC curve was 0.766+/-0.077 S.E. for EuroSCORE and 0.685+/-0.087 S.E. for Parsonnet score. For "morbidity" the area under ROC curve was 0.628+/-0.048 S.E. for EuroSCORE and 0.660+/-0.048 S.E. for Parsonnet score while for the LOS, ROC curves were 0.632+/-0.056 S.E. and 0.671+/-0.053 S.E. accordingly. Both scoring systems were adequately calibrated in our data. CONCLUSION: Parsonnet and EuroSCORE are equally applicable as mortality predictors in Saudi population. EuroSCORE was slightly better than Parsonnet scoring in predicting the mortality in medium and high risks categories. Both the systems have less discrimination for prediction of "morbidity" and LOS.