Off-pump coronary artery bypass surgery: physiology and anaesthetic management †

Evaluation of Oral Pregabalin as a Preemptive Adjuvant for Postoperative Pain in Patients Undergoing Coronary Artery Bypass Grafting With General Anesthesia and High Thoracic Epidural: A Randomized Controlled Study

Aim This study aimed to evaluate the effectiveness of oral pregabalin as a preventive supplement in managing postoperative pain in patients undergoing coronary artery bypass grafting (CABG) with a combination of general anesthesia and high thoracic epidural anesthesia. Material and methods This 18-month randomized controlled study at a tertiary hospital's anesthesiology department included 62 American Society of Anesthesiologists (ASA) II or III patients aged 35-75 with left ventricular ejection fraction >35%. Placebo (Group B, n = 31) or pregabalin (Group A, n = 31) was randomly allocated. Group A got 150 mg of pregabalin the night before surgery and 75 mg on postoperative days 0 and 1, whereas Group B received a placebo. Postoperative pain was evaluated using the Verbal Numerical Scale and Visual Analogue Scale, while sedation was assessed with the Ramsay Sedation Scale. Statistical analysis was performed using SPSS for Windows, Version 16.0 (Released 2007; SPSS Inc., Chicago). Results In this study, pregabalin significantly reduced postoperative pain on Day 0 and Day 1 (p < 0.001) compared to the placebo. The pregabalin group exhibited higher sedation scores on Day 0 (p < 0.001), but there were no significant differences on Day 1. Inotrope requirements were similar between both groups. Conclusions CABG patients' postoperative pain was greatly reduced by pregabalin without impacting sedation or inotrope needs. These data imply that pregabalin was a useful supplementary analgesic for CABG patients' multimodal pain treatment.

Inhaled iloprost in off-pump coronary artery bypass surgery: a randomized controlled trial

PURPOSE

Mechanical cardiac constraint during off-pump coronary artery bypass surgery (OPCAB) causes right ventricle (RV) compression and increased pulmonary artery pressure (PAP), which may further compromise RV dysfunction. We aimed to assess the effect of inhaled iloprost, a potent selective pulmonary vasodilator, on the cardiac index (CI) during mechanical constraint. The secondary aim was to determine the resultant changes in the hemodynamic and respiratory parameters.

METHODS

A total of 100 adult patients with three-vessel coronary artery disease who had known risk factors for hemodynamic instability (congestive heart failure, mean PAP ≥ 25 mm Hg, RV systolic pressure ≥ 50 mm Hg on preoperative echocardiography, left ventricular ejection fraction < 50%, myocardial infarction within one month of surgery, redo surgery, and left main disease) were enrolled in a randomized controlled trial. The patients were randomly allocated to the control or iloprost groups at a 1:1 ratio, in which saline and iloprost (20 μg) were inhaled for 15 min after internal mammary artery harvesting, respectively. Cardiac index was measured by pulmonary artery catheterization.

RESULTS

There were no significant intergroup differences in CI during grafting (P = 0.36). The mean PAP had a significant group-time interaction (P = 0.04) and was significantly lower in the iloprost group at circumflex grafting (mean [standard deviation], 26 [3] mm Hg vs 24 [3] mm Hg; P = 0.01). The remaining hemodynamic parameters were similar between the groups.

CONCLUSION

Inhaled iloprost showed a neutral effect on hemodynamic parameters, including the CI and pulmonary vascular resistance index, during OPCAB.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT04598191); first submitted 12 October 2020.

Mass intraoperative endothelial glycocalyx shedding affects postoperative systemic inflammation response

BACGROUND

Off-pump coronary artery bypass graft (OPCABG) has a high incidence of postoperative systemic inflammation response syndrome (SIRS), and perioperative endothelial glycocalyx layer (EGL) disruption can be one of the predisposing factors. We hypothesized that EGL shedding happened earlier in OPCABG which can influence on postoperative SIRS, and sevoflurane might preserve EGL better than propofol.

METHODS

We randomly allocated 50 patients undergoing OPCABG to receive either sevoflurane-sufentanil or propofol-sufentanil anesthesia. Plasma syndecan-1, heparan sulfate (HS), atrial natriuretic peptide (ANP), IL-6, and cardiac troponin I (cTnI) were measured. Blood samples were collected at 6 timepoints: induction (T1), before grafting (T2), after grafting(T3), surgery done (T4), postoperative day1 (POD1,T5) and POD2 (T6). SIRS criteria and sequential organ failure assessment (SOFA) score were examined.

RESULTS

There were neither differences of syndecan-1, HS, IL-6 nor of SIRS criteria or SOFA score between the sevoflurane and propofol groups. All patients were pooled as a single group for further statistical analyses, plasma syndecan-1 (P < 0.001) and IL-6 (P < 0.001) increased significantly as a function of time; syndecan-1 increasing correlated significantly with the duration of coronary graft anastomosis (r = 0.329, P = 0.026). Syndecan-1(T3) correlated significantly with ANP(T3) (r = 0.0.354, P = 0.016) and IL-6 (T5) (r = 0.570, P < 0.001). The maximum value of IL-6 correlated significantly with SIRS (r = 0.378, P = 0.010), the maximum value of SOFA score (r = 0.399, P = 0.006) and ICU days (r = 0.306, P = 0.039). The maximum value of SOFA score correlated significantly with the occurrence of SIRS (r = 0.568, P < 0.001) and ICU days (r = 0.338, P = 0.022).

CONCLUSIONS

OPCABG intraoperative early EGL shedding caused of grafts anastomosis greatly affected postoperative SIRS and SOFA score, sevoflurane did not clinically preserve EGL better.

TRIAL REGISTRATION

ChiCTR-IOR-17012535. Registered on 01/09/2017.

Comparative Evaluation of Dexmedetomidine and Magnesium Sulfate for Prevention of Postoperative Atrial Fibrillation in Patients of Coronary Artery Bypass Surgeries

Introduction The main goal of this study is to compare the effects of dexmedetomidine and magnesium sulfate on preventing atrial fibrillation (AF) after off-pump coronary artery bypass graft (CABG) surgeries. AF is a type of irregular heartbeat that often occurs after heart surgery and can cause serious complications. We want to see which drug is more effective in reducing the risk of AF in patients who have had CABG surgeries without using a heart-lung machine.  Materials and methods This was a randomized clinical study, conducted on patients of ASA classes III and IV who were the candidates for off-pump coronary artery bypass graft surgeries, which were conducted in the cardiac operating room from the period October 2020 to April 2021, at the Department of Anaesthesia, Jawaharlal Nehru Medical College, Sawangi, Meghe. All patients were aged between 30 and 85 years and with a left ventricular ejection fraction of above 40%. Results When the two groups were compared, the incidence of arrhythmias was more in group D (a group that received injection dexmedetomidine infusion), predominantly AF with an incidence of 50% more as compared to group M (a group that received injection magnesium sulfate infusion). When hemodynamic parameters were compared, events of bradycardia and hypotension were significantly higher in group D as compared to group M. The heart rate (HR), when compared between the two groups intraoperatively from the duration before induction of anesthesia till during sternum closure, has a significant p-value (0.0001). Similarly, when the mean arterial pressure (MAP) was compared between the two groups intraoperatively, significant hypotension was noted in group D (p-value = 0.0001). Postoperatively, in the intensive care unit when the HR and MAP were compared for 48 hours, bradycardia and hypotension were noted, but drastic changes in the mean values of the HR and MAP were not seen in both groups D and M. Conclusion When comparing the antiarrhythmic properties of the study drugs, it was observed that intraoperative and postoperative arrhythmias were less with magnesium sulfate as compared with dexmedetomidine. It was also found that there were higher events of hypotension and bradycardia in the dexmedetomidine group as compared to the magnesium sulfate group.

Off-Pump Coronary Artery Bypass Grafting Surgery: A Valuable 2-Day Experience

Currently, coronary artery disease (CAD) has been identified as the leading cause of mortality in Malaysia and in other countries worldwide. Genetic predisposition and comorbidities such as hypertension and diabetes mellitus, gender, lifestyle, and several other risk factors can contribute to the development of CAD. Pharmacological and surgical treatments play a vital role in improving the quality of life of patients with CAD. New surgical techniques and continuous interventions have been introduced to improve the treatment outcome. Recently, cardiothoracic teams from Universiti Teknologi MARA (UiTM) and Universiti Sains Malaysia (USM) have conducted a 2-day live workshop on off-pump coronary artery bypass (OPCAB) surgery. In this brief communication, we share the highlights and clinical tips of the OPCAB surgery gained from the collaboration.

CON: Propofol Is Better Than Etomidate for Induction in Cardiac Surgical Patients

There is an ongoing debate regarding the choice of ideal induction agent between propofol and etomidate for cardiac surgical patients. Etomidate appears to be better than propofol as the induction agent due to the superior hemodynamic stability. However, the adrenal suppression due to etomidate can pose challenges to the anesthesiologist in certain clinical situations.

Perioperative Nadir Hemoglobin Concentration and Outcome in Off-Pump Coronary Artery Bypass Surgery - A Retrospective Review

BACKGROUND

Emerging evidence advocates the use of restrictive transfusion strategies at hemoglobin (Hb) levels of approximately 7-8 g/dL in cardiac surgeries using cardiopulmonary bypass. Yet, it is unclear whether the same thresholds can be applied to off-pump coronary bypass (OPCAB) that accompanies cardiac displacement and warm regional ischemia-reperfusion injury without the aid of a bypass machine. The aim of this study is to investigate the relationship between perioperative nadir Hb level and outcome following OPCAB.

METHODS AND RESULTS

Medical records of 1,360 patients were reviewed. Hb levels were serially assessed during and after surgery. The incidence of composite endpoints was 35%, which included myocardial infarction, stroke, acute kidney injury, sternal infection, reoperation, prolonged mechanical ventilation, and in-hospital mortality. The nadir Hb level was significantly lower in the morbidity group than in the non-morbidity group (8.1 [7.4-9.1] vs. 8.8 [7.9-9.8] g/dL, P<0.001). Multivariable logistic regression analysis revealed nadir Hb as an independent risk factor of adverse outcome (odds ratio: 0.878, 95% confidence intervals: 0.776-0.994, P=0.04), whereas preoperative anemia and perioperative transfusion were not. The critical value of Hb for predicting detrimental outcome was 8.05 g/dL.

CONCLUSIONS

A significant association is found between perioperative nadir Hb and adverse outcome after OPCAB. Although preoperative anemia was not associated with poor prognosisper se, it was the only modifiable risk factor that was closely linked to nadir Hb.

Sudden, new-onset aortic regurgitation during off pump coronary bypass surgery

During off pump coronary artery bypass grafting surgery, it is common to observe mitral or tricuspid regurgitation due to heart displacement. But it's very unusual to notice new onset aortic regurgitation in OPCABG.

Ex Vivo Evaluation of a New Extracorporeal Lung Assist Device: NovaLung® Membrane Oxygenator

When lung function is compromised, alternative devices need to be deployed in order to maintain blood oxygenation. A new device, NovaLung®, has been designed for acute lung failure. We went about evaluating its gas exchange capability.

Three calves (79.5±7.8 kg) were connected to the NovaLung® System with a priming volume of 240 mL, gas exchange surface area of 1.3 m2 and exhibiting a biologically coated surface. A standard battery of blood samples were taken before implantation and over a six hour period.

Hematocrit remained stable ranging from 27±4% (baseline) to 29±5% (6 hrs). Platelets were preserved ranging from 882±27.4 U/L (baseline) to 734±147 (6 hrs). LDH remained stable at 719±85 U/L (baseline) vs 686±190 U/L (6 hrs) and the pressure drop was maintained below 20 mmHg. Minimal hemolysis was observed. Oxygen transfer peaked at two hours acute extracorporeal lung support (ECLS) with a mean value of 130±50 ml/min.

In conclusion, the device is easy to use, provides adequate O2 and CO2 transfer for partial lung support in an acute setting. Shows minimal signs of hemolysis and platelets levels are maintained throughout the six hour ECLS period.

Association Between Elevated Echocardiographic Index of Left Ventricular Filling Pressure and Acute Kidney Injury After Off-Pump Coronary Artery Surgery

BACKGROUND

The ratio of the early transmitral flow velocity to early diastolic velocity of the mitral annulus (E/e') is an echocardiographic index of mean left ventricular (LV) filling pressure. We investigated the association between the preoperative E/e' ratio and postoperative acute kidney injury (AKI) during off-pump coronary artery bypass surgery (OPCAB).Methods and Results:We reviewed 585 patients who underwent OPCAB and with preserved LV ejection fraction determined by preoperative echocardiography. AKI was determined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Multivariable logistic regression analysis was performed. E/e' was also analyzed as 3 categories (E/e' <8, 8≤E/e'≤15, and E/e' >15) and as a continuous variable. A propensity score analysis was used to match the patients with E/e' >15 and E/e' ≤15. A preoperative E/e' >15 was an independent predictor for AKI (odds ratio 3.01, 95% confidence interval 1.40-6.17). E/e' >15 was also an independent predictor for AKI when E/e' was analyzed with 3 categories or as a continuous variable. In the matched sample, the incidence of AKI and 1-year mortality was significantly higher in patients with E/e' >15.

CONCLUSIONS

Among patients undergoing OPCAB with preserved LV systolic function, a preoperative E/e' ratio >15 was an independent predictor of postoperative AKI. Measurement of the preoperative E/e' ratio may help to assess the risk of postoperative AKI.

Morphologic Evaluation of the Mitral Annulus During Displacement of the Heart in Off-Pump Coronary Artery Bypass Surgery

OBJECTIVE

To evaluate the morphologic changes of the mitral annulus using 3-dimensional transesophageal echocardiography during heart displacement to expose the anastomosis site in off-pump coronary artery bypass surgery (OPCAB).

DESIGN

Prospective case series.

SETTING

Single center, university hospital.

PARTICIPANTS

The study comprised 34 consecutive patients who underwent OPCAB of the left circumflex artery (LCX) and the right coronary artery (RCA).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Mitral annulus parameters were measured using the Mitral Valve Quantification program after sternotomy (physiologic position) and during displacement of the heart to expose the LCX (LCX position) and the RCA (RCA position). The height of the mitral annulus was significantly lower in the LCX (5.76 ± 0.90 mm) and RCA (5.92 ± 0.97 mm) positions than in the physiologic position (6.96 ± 0.99 mm; both p < 0.0001). The percent change in the height of the mitral annulus was significantly greater in the mitral regurgitation group than in the mitral regurgitation nondeterioration group when in the LCX (-16.3% ± 6.0% v -11.9% ± 3.3%, p = 0.0203) and RCA (-16.9% ± 6.3% v -12.1% ± 3.8%, p = 0.0207) positions. The anteroposterior and intercommissural diameters, annulus perimeter, and surface area of the mitral annulus did not differ significantly among all heart positions.

CONCLUSIONS

The mitral annulus flattened and lost its saddle shape without expanding while in the LCX and RCA positions. The greater percent change in the height of the mitral annulus may aggravate mitral regurgitation.

Sodium bicarbonate does not prevent postoperative acute kidney injury after off-pump coronary revascularization: a double-blinded randomized controlled trial

BACKGROUND

Acute kidney injury (AKI) is a common morbidity after off-pump coronary revascularization. We investigated whether perioperative administration of sodium bicarbonate, which might reduce renal injury by alleviating oxidative stress in renal tubules, prevents postoperative AKI in off-pump coronary revascularization patients having renal risk factors.

METHODS

Patients (n=162) having at least one of the following AKI risk factors were enrolled: (i) age >70 yr; (ii) diabetes mellitus; (iii) chronic renal disease; (iv) congestive heart failure or left ventricular ejection fraction <35%; and (v) reoperation or emergency. Patients were evenly randomized to receive either sodium bicarbonate (0.5 mmol kg^-1 for 1 h upon induction of anaesthesia followed by 0.15 mmol kg^-1 h^-1 for 23 h) or 0.9% saline. Acute kidney injury within 48 h after surgery was assessed using the Acute Kidney Injury Network criteria.

RESULTS

The incidences of AKI were 21 and 26% in the bicarbonate and control groups, respectively (P=0.458). Serially measured serum creatinine concentrations and perioperative fluid balance were also comparable between the groups. The length of postoperative hospitalization and incidence of morbidity end points were similar between the groups, whereas significantly more patients in the bicarbonate group required prolonged mechanical ventilation (>24 h) relative to the control group (20 vs 6, P=0.003).

CONCLUSIONS

Perioperative sodium bicarbonate administration did not decrease the incidence of AKI after off-pump coronary revascularization in high-risk patients and might even be associated with a need for prolonged ventilatory care.

CLINICAL TRIAL REGISTRATION

NCT01840241.

Serum protein S100 as marker of postoperative delirium after off-pump coronary artery bypass surgery: secondary analysis of two prospective randomized controlled trials

Background:

To investigate the predictive value of S100 (biochemical marker of neuroglial injury) for the occurrence of postoperative delirium (POD) in patients undergoing off-pump coronary artery bypass (OPCAB)-surgery.

Methods:

We enrolled 92 patients older than 18 years undergoing elective OPCAB-surgery. Serum-levels of S100 were determined at baseline (BL), end of surgery (EOS) and on the first postoperative day (PD1). Postoperatively, all-patients were evaluated daily until PD5 for the presence of POD using the confusion assessment method (CAM) or the confusion assessment method for the intensive care unit (CAM-ICU) for patients in the intensive care unit (ICU).

Results:

The overall incidence of POD was 21%. S100-values on PD1 significantly predicted the occurrence of POD during the later hospital stay [area under the curve (AUC)=0.724 (95% confidence interval (CI): 0.619–0.814); p=0.0001] with an optimal cut-off level of 123 pg mL

Conclusions:

S100-levels <123 pg mL

Double-blinded, randomized controlled trial of N-acetylcysteine for prevention of acute kidney injury in high risk patients undergoing off-pump coronary artery bypass

AIM

The aim of this study was to investigate the influence of perioperative N-acetylcysteine (NAC) administration, a known antioxidant, on the incidence of acute kidney injury (AKI) after off-pump coronary bypass surgery (OPCAB) in patients with known risk factors of AKI.

METHODS

One hundred and seventeen patients with ≥1 of the following risk factors of AKI were randomized into either the control (n = 57) or the NAC (n = 60) group; (i) preoperative serum creatinine >1.4 mg/dL; (ii) left ventricular ejection fraction <35% or congestive heart failure (iii) age >70 years (iv) diabetes or (v) re-operation. Patients in the NAC group received 150 mg/kg of NAC IV bolus at anaesthetic induction followed by a continuous infusion at 150 mg/kg per day for 24 h. AKI was diagnosed based on Acute Kidney Injury Network criteria during 48 h postoperatively.

RESULTS

The incidence of AKI was 32% (19/60) and 35% (20/57) in the control and the NAC group, respectively (P = 0.695). The serum concentrations of creatinine and cystatin C were similar between the groups throughout the study period. Fluid balance including the amount of blood loss and transfusion requirement were similar between the groups except the amount of postoperative urine output, which was higher in the control group compared with the NAC group (5528 ± 1247 mL vs. 4982 ± 1185 mL, control vs. NAC, P = 0.017).

CONCLUSION

Perioperative administration of NAC did not prevent the development of postoperative AKI after OPCAB in highly susceptible patients to AKI.

An Integrated Approach to von Willebrand Disease and Surgical Myocardial Revascularization

Cardiac surgery in patients with preexisting bleeding disorders can be a challenge. Cardiopulmonary bypass can lead to bleeding disorders, above all in patients with coagulopathy. We report the case of a 42-year-old woman, with type I von Willebrand disease, who underwent off-pump coronary artery bypass grafting. Beating heart surgery associated with an adequate replacement of von Willebrand factor and factor VIII levels were chosen to prevent bleeding disorders. Her postoperative course was uneventful and she was discharged home after 5 postoperative days.

Risk of renal dysfunction after less invasive multivessel coronary artery bypass grafting

OBJECTIVE

Several centers have established that off-pump, multivessel coronary artery bypass grafting performed via a small thoracotomy (MVST) is feasible. However, this procedure can be challenging when posterolateral coronary targets need to be grafted. We hypothesized that use of cardiopulmonary bypass via peripheral access (MVST-PA) would improve outcomes compared with a completely off-pump approach (OP-MVST).

METHODS

This was a prospective observational study of patients undergoing OP-MVST (n = 46) versus MVST-PA (n = 45) using bilateral internal mammary artery grafts onto the left anterior descending coronary artery and circumflex/right coronary artery distribution. Hemostasis was quantified by measuring platelet function (aggregometry), chest tube output, thrombolysis in myocardial infarction bleeding score (%hematocrit change at 24 hours), and transfusion requirements. The rate of mortality and major morbidity at 30 days was defined according to The Society of Thoracic Surgeons criteria. Estimated glomerular filtration rate (normalized to baseline levels) was determined daily until discharge.

RESULTS

The OP-MVST versus MVST-PA groups had similar risk factors at baseline and risks of composite morbidity/mortality at 30 days. However, renal failure was significantly increased after OP-MVST (10.87 vs 0%, P = 0.05), and MVST-PA affected hemostasis as evidenced by inhibition of platelet function (latency to response on aggregometry, 29.9 vs 17.9 seconds; P = 0.04) and higher transfusion requirement (2.31 vs 0.85 units of red blood cells/patient, P = 0.04; 55.6% vs 34.8% transfused; P = 0.059). However, 24-hour chest tube output was similar (645 vs 750 mL; P = 0.53).

CONCLUSIONS

In comparison with a completely off-pump strategy, use of cardiopulmonary bypass to assist MVST reduced the risk of renal dysfunction with only modest tradeoffs in other morbidities, for example, altered coagulation and higher transfusion requirements. These data justify further study of the effect of MVST-PA on renal complications.

A comparative study of cardioprotective effect of three anesthetic agents by measuring serum level of troponin-T after coronary artery bypass grafting

BACKGROUND

Cardiac surgery is associated with some degree of myocardial injury. Preconditioning first described in 1986 was pharmacologic and non- pharmacologic. Among the long list of anesthetic drugs, isoflurane as an inhaling agent along with midazolam and propofol as injectable substances have been documented to confer some preconditioning effects on myocardium.

OBJECTIVES

In this study cardiac Troponin T (cTnT) ,as a reliable marker, was used for evaluating myocardial injury.

METHODS

This prospective double blind study was comprised of 60 patients scheduled for CABG and were randomly assigned into three groups who received infusion of propofol or midazolam or isoflorane. Surgical procedures and anesthetics were similar for 3 groups. cTnT measured preoperatively and at 12, 24 and 36hr after arrival in ICU.

RESULTS

There were no statistically significant differences in mean cTnT levels between three groups in the preoperative period and 12-24 hours after arrival in ICU. However, mean cTnT in 3 groups at 36 hours after arrival in ICU were different (P< 0.013) and cTnT level was significantly higher in midazolam group (P<0.001) and lowest in isoflurane group (P=0.002).

CONCLUSION

There were significant differences on cTnT levels between anesthetic groups of isofluran, midazolam and propofol at 36 hr after surgery. Preconditioning effect of isoflurane was higher than the other two groups.

Deep Pericardial Traction Suture versus Vacuum-Assisted Apical Suction to Expose the Posterior Wall of the Heart in Off-Pump Coronary Artery Bypass: A Prospective, Randomized Study

<p><b>Background:</b> Displacement of the heart to expose the posterior vessels during off-pump coronary artery bypass (OPCAB) may cause hemodynamic instability. Deep pericardial traction suture (DPTS) and vacuum-assisted apical suction (VAS) with the Starfish positioning device help to provide good exposure without relevant hemodynamic changes. Our aim was to compare these two methods in patients undergoing multivessel OPCAB.</p><p><b>Methods:</b> We prospectively randomized 20 patients undergoing multivessel OPCAB to the use of VAS or DPTS. The Octopus device was used in both groups to stabilize the target vessel. Hemodynamic parameters, including venous oxygen content (SvO₂₎, cardiac index (CI), central venous pressure (CVP), mean arterial pressure (MAP), pulmonary artery pressure (PAP), and pulmonary capillary wedge pressure (PCWP), were measured before grafting (baseline), after heart positioning, and during performance of peripheral anastomoses.</p><p><b>Results:</b> Perioperative data for the two groups were similar. During exposure of the lateral wall, there were fewer hemodynamic changes in the DPTS group (increase in CVP) than in the VAS group (increases in CVP, PAP, and PCWP); the CVP was significantly higher in the DPTS group (<i>P</i> < .05). During exposure of the posterior wall, significant hemodynamic changes occurred only in the DPTS group (increase in PCWP). Values for all other parameters were similar, including anastomosis time, graft flow, postoperative myocardial enzymes, and inotropic support.</p><p><b>Conclusions:</b> Heart positioning during OPCAB with either VAS or DPTS is a safe and effective maneuver for exposure of coronary arteries. In our study, the use of the VAS device produced less hemodynamic impairment during exposure of the lateral and posterior walls.</p>

Effect of tranexamic acid on transfusion requirement in dual antiplatelet-treated anemic patients undergoing off-pump coronary artery bypass graft surgery

BACKGROUND

Anemia is not rare in patients presenting for coronary artery bypass graft surgery (CABG) and as these patients are frequently on dual antiplatelet therapy (DAPT), the coexisting conditions could potentially increase the risk of bleeding and transfusion. The aim of this study was to evaluate the effect of tranexamic acid (TA) on blood loss and transfusion in preoperatively anemic patients who continued DAPT until within 5 days of off-pump CABG (OPCAB).

METHODS AND RESULTS

Seventy-six anemic patients were randomized into 2 groups: TA group receiving TA (1g bolus followed by infusion at 200mg/h) and a Control group receiving the same volume of saline. The amount of blood loss and transfusion requirement during, and at 4 and 24h after the operation were assessed. Patients' characteristics and operative data were similar between the groups. During the perioperative period, which combined the intraoperative and postoperative 24h data, the TA group received significantly smaller amounts of packed red blood cells and fresh frozen plasma. Total amount of perioperative blood loss was similar between the groups, although the blood loss during the postoperative 4h was significantly less in the TA group.

CONCLUSIONS

TA infusion could reduce the amount of transfusion during the perioperative period in patients with preoperative anemia who continue DAPT until within 5 days of OPCAB.

Haemodynamic changes during left anterior descending artery exposure in off-pump coronary artery bypass: comparison between use of moist laparotomy pads and deep pericardial traction sutures for heart displacement

Haemodynamic changes occurring during heart displacement, using moist laparotomy pads placed behind the heart (PAD group, n = 26) or deep pericardial traction sutures (DPS group, n = 25) to facilitate exposure of the left anterior descending artery during off-pump coronary artery bypass surgery, were compared. Haemodynamic variables were assessed before and 10 min after displacement of the heart. The central venous pressure, mean pulmonary artery pressure and pulmonary capillary wedge pressure increased in both groups. After heart displacement in the PAD group, the cardiac index, stroke volume index, mixed venous oxygen saturation, right ventricular ejection fraction and left ventricular stroke work index decreased significantly, and the systemic vascular resistance and pulmonary vascular resistance increased significantly; these parameters remained unchanged in the DPS group. It was concluded that displacement of the heart using moist laparotomy pads caused significant haemodynamic derangement compared with that caused by deep pericardial traction sutures.

Intensified thermal management for patients undergoing transcatheter aortic valve implantation (TAVI)

Background

Transcatheter aortic valve implantation via the transapical approach (TAVI-TA) without cardiopulmonary bypass (CPB) is a minimally invasive alternative to open-heart valve replacement. Despite minimal exposure and extensive draping perioperative hypothermia still remains a problem.

Methods

In this observational study, we compared the effects of two methods of thermal management on the perioperative course of core temperature. The methods were standard thermal management (STM) with a circulating hot water blanket under the patient, forced-air warming with a lower body blanket and warmed infused fluids, and an intensified thermal management (ITM) with additional prewarming using forced-air in the pre-operative holding area on the awake patient.

Results

Nineteen patients received STM and 20 were treated with ITM. On ICU admission, ITM-patients had a higher core temperature (36.4 ± 0.7°C vs. 35.5 ± 0.9°C, p = 0.001), required less time to achieve normothermia (median (IQR) in min: 0 (0-15) vs. 150 (0-300), p = 0.003) and a shorter period of ventilatory support (median (IQR) in min: 0 (0-0) vs. 246 (0-451), p = 0.001).

Conclusion

ITM during TAVI-TA reduces the incidence of hypothermia and allows for faster recovery with less need of ventilatory support.

Epidural anesthesia and postoperative analgesia with ropivacaine and fentanyl in off-pump coronary artery bypass grafting: a randomized, controlled study

Background

Our aim was to assess the efficacy of thoracic epidural anesthesia (EA) followed by postoperative epidural infusion (EI) and patient-controlled epidural analgesia (PCEA) with ropivacaine/fentanyl in off-pump coronary artery bypass grafting (OPCAB).

Methods

In a prospective study, 93 patients were scheduled for OPCAB under propofol/fentanyl anesthesia and randomized to three postoperative analgesia regimens aiming at a visual analog scale (VAS) score < 30 mm at rest. The control group (n = 31) received intravenous fentanyl 10 μg/ml postoperatively 3-8 mL/h. After placement of an epidural catheter at the level of Th₂-Th₄ before OPCAB, a thoracic EI group (n = 31) received EA intraoperatively with ropivacaine 0.75% 1 mg/kg and fentanyl 1 μg/kg followed by continuous EI of ropivacaine 0.2% 3-8 mL/h and fentanyl 2 μg/mL postoperatively. The PCEA group (n = 31), in addition to EA and EI, received PCEA (ropivacaine/fentanyl bolus 1 mL, lock-out interval 12 min) postoperatively. Hemodynamics and blood gases were measured throughout 24 h after OPCAB.

Results

During OPCAB, EA decreased arterial pressure transiently, counteracted changes in global ejection fraction and accumulation of extravascular lung water, and reduced the consumption of propofol by 15%, fentanyl by 50% and nitroglycerin by a 7-fold, but increased the requirements in colloids and vasopressors by 2- and 3-fold, respectively (P < 0.05). After OPCAB, PCEA increased PaO₂/FiO₂ at 18 h and decreased the duration of mechanical ventilation by 32% compared with the control group (P < 0.05).

Conclusions

In OPCAB, EA with ropivacaine/fentanyl decreases arterial pressure transiently, optimizes myocardial performance and influences the perioperative fluid and vasoactive therapy. Postoperative EI combined with PCEA improves lung function and reduces time to extubation.

Trial Registration

NCT01384175

Pulse-pressure variation predicts fluid responsiveness during heart displacement for off-pump coronary artery bypass surgery

OBJECTIVE

The aim of this study was to evaluate the ability of pulse-pressure variation to predict fluid responsiveness during heart displacement for off-pump coronary artery bypass surgery using receiver operating characteristic analysis.

DESIGN

A prospective study.

SETTING

A clinical study in a single cardiac anesthesia institution.

PARTICIPANTS

Thirty-five patients undergoing elective off-pump coronary artery bypass surgery.

MEASUREMENTS AND MAIN RESULTS

Central venous pressure, pulmonary arterial occlusion pressure, pulse-pressure variation, and cardiac index were measured 5 minutes after revascularization of the left anterior descending coronary artery and before heart displacement. Immediately after heart displacement for revascularization of the left circumflex artery, and 10 minutes after fluid loading with hydroxyethyl starch 6% (10 mL/kg) during heart displacement, the measurements were repeated. Patients whose cardiac indices increased by ≥15% from fluid loading were defined as responders. After heart displacement, only pulse-pressure variation showed significant difference between the responders and nonresponders (13.48 ± 6.42 v 7.33 ± 3.81, respectively; p < 0.01). Moreover, receiver operating characteristic analysis showed that pulse-pressure variation successfully predicted fluid responsiveness (area under the curve = 0.839, p = 0.0001). Pulse-pressure variation >7.69% identified the responders, with a sensitivity of 86% and a specificity of 83%.

CONCLUSIONS

Pulse-pressure variation successfully predicted fluid responsiveness and would be useful in guiding fluid management during heart displacement for off-pump coronary artery bypass surgery.

Hemodynamic changes during myocardial revascularization without extracorporeal circulation

BACKGROUND AND OBJECTIVES

Cardiac positioning and stabilization during myocardial revascularization without extracorporeal circulation (ECC) may cause hemodynamic changes dependent to the surgical site. The objective of this study was to evaluate these changes during distal coronary anastomosis.

METHODS

Twenty adult patients undergoing myocardial revascularization without ECC were monitored by pulmonary artery catheter and transesophageal Echo Doppler. Hemodynamic data were collected at the following times before removing the stabilizer wall: (1) after volume adjustments, (2) at the beginning of distal anastomosis, and (3) after 5 minutes. Treated coronary arteries were grouped according to their location in the lateral, anterior, or posterior wall. Two-way ANOVA with repetition and Newman-Keuls post-test were used in the analysis. A p value < 0.05 was considered statically significant.

RESULTS

During myocardial revascularization without ECC, pulmonary artery wedge pressure showed elevation from 17.7 ± 6.1 to 19.2 ± 6.5 (p < 0.001) and 19.4 ± 5.9 mmHg (p < 0.001), while the central venous pressure went from 13.9 ± 5.4 to 14.9 ± 5.9 mmHg (p = 0.007) and 15.1 ± 6.0 mmHg (p = 0.006). Intermittent cardiac output was reduced from 4.70 ± 1.43 to 4.23 ± 1.22 (p < 0.001) and 4.26 ± 1.25 L.min(-1) (p < 0.001). According to transesophageal Doppler, a significant group-time interaction was observed in cardiac output, which was reduced in the lateral group from 4.08 ± 1.99 to 2.84 ± 1.82 (p = 0.02) and 2.86 ± 1.73 L.min(-1) (p = 0.02), and aortic blood flow, which went from 2.85 ± 1.39 to 1.99 ± 1.26 (p = 0.02) and 2.00 ± 1.21 L.min(-1) (p = 0.02). Other hemodynamic changes were not observed during anastomoses.

CONCLUSIONS

A significant hemodynamic deterioration was observed during myocardial revascularization without ECC. Transesophageal Doppler detected a decrease in cardiac output only in the lateral group.

The uncalibrated pulse contour cardiac output during off-pump coronary bypass surgery: performance in patients with a low cardiac output status and a reduced left ventricular function

BACKGROUND

We compared the continuous cardiac index measured by the FloTrac/Vigileo™ system (FCI) to that measured by a pulmonary artery catheter (CCI) with emphasis on the accuracy of the FCI in patients with a decreased left ventricular ejection fraction (LVEF) and a low cardiac output status during off-pump coronary bypass surgery (OPCAB). We also assessed the influence of several factors affecting the pulse contour, such as the mean arterial pressure (MAP), the systemic vascular resistance index (SVRI) and the use of norepinephrine.

METHODS

Fifty patients who were undergoing OPCAB (30 patients with a LVEF ≥ 40%, 20 patients with a LVEF < 40%) were enrolled. The FCI and CCI were measured and we performed a Bland-Altman analysis. Subgroup analyses were done according to the LVEF (< 40%), the CCI (≤ 2.4 L/min/m), the MAP (60-80 mmHg), the SVRI (1,600-2,600 dyne/s/cm(5)/m(2)) and the use of norepinephrine.

RESULTS

The FCI was reliable at all the time points of measurement with an overall bias and limit of agreement of -0.07 and 0.67 L/min/m(2), respectively, resulting in a percentage error of 26.9%. The percentage errors in the patients with a decreased LVEF and in a low cardiac output status were 28.2% and 22.3%, respectively. However, the percentage error in the 91 data pairs outside the normal range of the SVRI was 40.2%.

CONCLUSIONS

The cardiac output measured by the FloTrac/Vigileo™ system was reliable even in patients with a decreased LVEF and in a low cardiac output status during OPCAB. Acceptable agreement was also noted during the period of heart displacement and grafting of the obtuse marginalis branch.

The effect of milrinone on the intraoperative hemodynamics during off-pump coronary bypass surgery in patients with an elevated echocardiographic index of the ventricular filling pressure

BACKGROUND

Hemodynamic derangement during off-pump coronary artery bypass surgery (OPCAB) is mainly attributed to impaired filling and diastolic dysfunction. An elevated ratio of the mitral velocity to the early-diastolic velocity of the mitral annulus (E/e' > 15) is a relatively new indicator of diastolic function, and this was reported to be associated with impaired hemodynamics during OPCAB. We investigated the efficacy of milrinone on the perioperative hemodynamics and short term outcomes of patients with an E/e' > 15 and who underwent OPCAB.

METHODS

The patients were randomly allocated into either group C (control, n = 31) or group M (n = 31) and they were treated with the same amount of either normal saline or milrinone (0.5 µg/kg/min) without bolus loading after completion of internal mammary artery harvest until the end of operation. Hemodynamic measurements were recorded after the induction of anesthesia (T1), 5 min after starting each distal anastomosis of the left anterior descending artery (T2), left circumflex artery (T3) and right coronary artery (T4), and 5 min after sternum closure (T5).

RESULTS

The mixed venous oxygen saturation (SvO(2)) was lower through T2-T4 compared to the baseline value in both groups, while the degree of the decrease was significantly less in group M than that in group C. The other hemodynamic variables, the operative data and the postoperative outcomes were similar between the two groups.

CONCLUSIONS

Intraoperative infusion of milrinone did not significantly improve the perioperative hemodynamics and the subsequent short term outcomes for the patients with preexisting diastolic dysfunction as represented by an elevated E/e' value, although it reduced the degree of decrease of the SvO(2) during OPCAB.

Off-pump coronary artery surgery with the Coronéo Cor-Vasc stabilizing device: clinical experience of 141 patients

OBJECTIVES

Numerous devices have been successfully introduced in off-pump coronary artery bypass graft (OPCABG) surgery, most of them being disposable tools based on suction stabilization. Coronéo Cor-Vasc is a reusable system combining suction positioning with compression stabilization. The purpose of this study was to analyze our experience in OPCABG with the Cor-Vasc system.

METHODS

Between March 2001 and May 2008, 141 patients (age = 71.1 +/- 7.5 years) underwent OPCABG surgery using the Cor-Vasc system, representing 6.3% of the case volume of isolated coronary artery bypass graft surgery in the same period. Eighty-eight patients (62.4%) underwent surgery on an urgent basis. In 95 patients (67.4%), the OPCABG option was selected after finding a diseased ascending aorta at intraoperative epiaortic ultrasound.

RESULTS

Among 334 anastomoses (mean = 2.4 +/- 1 per patient), 242 (95 patients) were fashioned with bilateral and 54 (46 patients) with single internal thoracic artery, respectively. In 89.4 and 73% of patients, a complete and a total arterial myocardial revascularization was achieved, respectively. There were two strokes (1.4%) and two myocardial infarctions (1.4%). Two patients died in the hospital (1.4%). Median ICU and in-hospital length of stay were 31.2 h and 10 days, respectively.

CONCLUSION

In our experience, the use of the Cor-Vasc system, including the device-learning curve, was associated with low mortality and morbidity indexes in an aged population with a high risk of stroke. The system appeared to be sufficiently versatile and potentially cost-effective when compared with disposable devices.

Effects of early vital capacity maneuver on respiratory variables during multivessel off-pump coronary artery bypass graft surgery

OBJECTIVES

Despite avoiding cardiopulmonary bypass, similar degrees of pulmonary impairment compared with on-pump coronary artery bypass surgery have been demonstrated in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB) compared with on-pump coronary artery bypass surgery. To investigate the effects of an early vital capacity maneuver (VCM) on intrapulmonary shunt (Qs/Qt), oxygenation, and pulmonary outcome in OPCAB.

DESIGN

Prospective, randomized, controlled, double-blind clinical trial.

SETTING

Cardiothoracic operating room and intensive care unit (ICU) of a university hospital.

PATIENTS

Fifty patients scheduled for OPCAB were randomized to treatment with VCM or none.

INTERVENTIONS

After sternotomy, VCM was performed by inflating the lungs to 40 cm H2O and holding this pressure for 10 seconds.

MEASUREMENTS AND MAIN RESULTS

Qs/Qt, Pao2/Fio2 (P/F) ratio, and dynamic and static pulmonary compliances were measured before induction of anesthesia (T0), 15 minutes after tracheal intubation (T1), during Y-graft construction (T2), 15 minutes after completion of grafting (T3), 15 minutes after sternal closure (T4), and 3 hours after arrival at the ICU (T5). Qs/Qt was lower and P/F ratio was higher in the VCM group at T2 through T5. Pulmonary compliances were also higher in the VCM group at T4 and T5. Patients in the VCM group were extubated earlier.

CONCLUSIONS

The beneficial effects of an early VCM on Qs/Qt persisted into the period of ICU care, with an improvement in P/F ratio and preserved pulmonary compliances, leading to a shorter time to extubation.

Single transpulmonary thermodilution and continuous monitoring of central venous oxygen saturation during off-pump coronary surgery

BACKGROUND

Off-pump coronary artery bypass grafting (OPCAB) requires thorough monitoring of hemodynamics and oxygen transport. Our aim was to find out whether therapeutic guidance during and after OPCAB, using an algorithm based on advanced monitoring, influences perioperative hemodynamic and fluid management as well as the length of post-operative ICU and hospital stay.

METHODS

Patients were randomized into two groups of hemodynamic monitoring: the conventional monitoring (CM) group (n=20) and the advanced monitoring (AM) group (n=20). In the CM group, therapy was guided by central venous pressure, mean arterial pressure (MAP) and heart rate (HR), and in the AM group by the intrathoracic blood volume index, MAP, HR, central venous oxygen saturation (ScvO(2)) and cardiac index (CI). The measurements were performed before and during surgery, and at 2, 4 and 6 h post-operatively.

RESULTS

In the AM group, colloids and dobutamine were given more frequently and were accompanied by increments in ScvO(2), CI and oxygen delivery compared with baseline. The percentage of ephedrine administration was higher in the CM group. The algorithm guided by AM decreased time until achieving the status of 'fit for ICU discharge' and post-operative hospital stay by 15% and 25%, respectively.

CONCLUSIONS

A goal-directed algorithm based on advanced hemodynamic monitoring and continuous measurement of ScvO(2) facilitates early detection and correction of hemodynamic changes and influences the strategy for fluid therapy that can improve the course of post-operative period after coronary artery bypass grafting on the beating heart.

Relationship between echocardiographic index of ventricular filling pressure and intraoperative haemodynamic changes during off-pump coronary bypass surgery

BACKGROUND

The ratio of mitral velocity to early-diastolic velocity of the mitral annulus (E/e') is an indicator of diastolic function representing acute loading conditions of the left ventricle. We tested the efficacy of E/e' as a predictor of haemodynamic derangement during off-pump coronary artery bypass surgery (OPCAB), when heart displacement causes loading changes.

METHODS AND RESULTS

Fifty patients with left ventricular (LV) ejection fraction >or= 50% were divided into two groups; E/e'<8 (normal LV filling pressure, n=25) and >15 (increased LV filling pressure, n=25). Haemodynamic measurements were recorded after induction of anaesthesia, during grafting, and after sternum closure. Patients' characteristics and operative data were similar between the groups. Cardiac index and mixed venous oxygen saturation were significantly lower during grafting and after sternum closure in the E/e'>15 group, compared with E/e'<8 group and with the baseline values. The E/e'>15 group required significantly longer ventilation time and length of stay in the intensive care unit.

CONCLUSIONS

Even in patients with preserved systolic LV function, patients with E/e'>15 were more prone to undergo a significant decrease in cardiac output during OPCAB, which did not return to baseline level after completion of grafting. Whether this finding is associated with increased morbidity and mortality should be validated.

Brain function monitoring during off-pump cardiac surgery: a case report

Background

Early postoperative stroke is an adverse syndrome after coronary bypass surgery. This report focuses on overcoming of cerebral ischemia as a result of haemodynamic instability during heart enucleation in off-pump procedure.

Case presentation

A 67 year old male patient, Caucasian race, with a body mass index of 28, had a recent non-Q posterolateral myocardial infarction one month before and recurrent instable angina. His past history includes an uncontrolled hypertension, dyslipidemia, insulin dependent diabetes mellitus, epiaortic vessel stenosis. The patient was scheduled for an off-pump procedure and monitored with bilateral somatosensory evoked potentials, whose alteration signalled the decrement of the cardiac index during operation.

The somatosensory evoked potentials appeared when the blood pressure was increased with a pharmacological treatment.

Conclusion

During the off-pump coronary bypass surgery, a lower cardiac index, predisposes patients, with multiple stroke risk factors, to a reduction of the cerebral blood flow. Intraoperative somatosensory evoked potentials monitoring provides informations about the functional status of somatosensory cortex to reverse effects of brain ischemia.