Intraoperative Myocardial Ischemia Research Articles

Efficacy and short-term outcomes of myocardial protection using single-dose histidine-tryptophan-ketoglutarate cardioplegia during aortic root surgery with different duration of myocardial ischemia

Objective: To explore the efficacy of myocardial protection with single-dose histidine-tryptophan-ketoglutarate (HTK) cardioplegia during aortic root operation, and the correlation between short-term clinical outcomes and duration of myocardial ischemia. Methods: The data of clinical cases undergoing myocardial protection with single-dose HTK cardioplegia during aortic root operation from January 2018 to December 2022 were retrospectively reviewed. Patients were divided into conventional HTK cardioplegia group (<3 h) and prolonged HTK cardioplegia group (≥3 h) according to duration of intraoperative myocardial ischemia. A 1∶1 propensity score matching was performed and the correlations between duration of myocardial ischemia and postoperative short-term outcomes (30-day mortality, readmission, mechanical circulation support and renal insufficiency) were analyzed. Results: A total of 282 patients were included in the final analysis, with 210 cases in the conventional HTK cardioplegia group and 72 cases inthe prolonged HTK cardioplegia group before matching. After matching, there were 64 cases (53 males and 11 females) in the conventional HTK cardioplegia group, with a mean age of (49.4±14.2) years. The prolonged HTK cardioplegia group had 64 cases (55 males and 9 females), with a mean age of (50.5±12.3) years. Higher sensitivity troponin [12 h: 10.1 (4.6, 18.7) μg/Lvs 4.1(2.2, 8.6) μg/L, P=0.002; 24 h: 7.7 (4.5, 19.0) μg/L vs 4.8 (2.2, 11.9) μg/L, P=0.025] and creatine kinase isoenzyme[12 h: 46.3 (28.1, 62.4) μg/L vs 20.7(14.1, 32.9) μg/L, P<0.001; 24 h: 26.3(13.4, 49.2) μg/L vs 14.5 (10.1, 33.5)μg/L, P=0.011] after surgery was detected in prolonged HTK cardioplegia group. Comparisons of other primary and secondary endpoint events showed no significant differences between the two groups (all P>0.05). Multivariate binary logistic regression showed that duration of myocardial ischemia had no significant effect on postoperative 30-day mortality (OR=1.255, 95%CI: 0.500-3.148, P=0.629), 30-day readmission (OR=0.378, 95%CI: 0.069-2.065, P=0.261) and mechanical circulation support (OR=0.991, 95%CI: 0.331-2.970, P=0.998). Conclusion: During aortic root surgery, single-dose HTK cardioplegia may provide satisfactory myocardial protection, and there was no significant correlation between duration of myocardial ischemia and short-term clinical outcomes.

Iatrogenic right coronary artery occlusion during minimally invasive cardiac surgery-tricuspid annuloplasty—a case report

Although rare, right coronary artery (RCA) injury is a serious complication of tricuspid annuloplasty (TAP) and warrants close attention. We report a case of ST elevation myocardial infarction secondary to iatrogenic RCA occlusion during minimally invasive cardiac surgery (MICS). Electrocardiography (ECG) revealed ST segment elevation in lead II. Transesophageal echocardiography (TEE) revealed inferior wall hypokinesis after cardiopulmonary bypass, and coronary angiography revealed peripheral RCA occlusion. Intraoperatively, we detected an atrioventricular groove deformity during the second surgical procedure. Wall motion and ECG abnormalities showed normalization after TAP was reestablished. Vigilant monitoring using TEE and ECG is important to detect intraoperative myocardial ischemia during MICS-TAP.

Patients of risk groups in the perioperative period: the review of modern guidelines

Background. According to the Decree of the Ministry of Health of Ukraine № 275 issued on 11.09.2018, there is a list of measures to ensure surgical safety and patient’s safety. These measures can be divided into those that should be performed 1) before anesthesia; 2) before skin dissection; 3) before the patient leaves the operating room. Perioperative medicine (POM) is a patient-centered and interdisciplinary perioperative care for surgical patients.&#x0D; Objective. To describe the current recommendations for POM.&#x0D; Materials and methods. Review of available guidance documents.&#x0D; Results and discussion. The pathophysiology of postoperative complications (infectious processes, intestinal paralysis, respiratory failure, kidney damage, etc.) includes the following factors: triggers (anxiety, pain, surgical trauma), patient factors (age, comorbid conditions), the consequences of general operative stress (autonomous system imbalance, inflammation, coagulopathy, metabolic imbalance). Clinical evaluation or biomarkers should be used to identify high-risk patients in the perioperative period. Measures to improve postoperative rehabilitation should be carried out in the pre-, intra- and postoperative period. Thus, in the preoperative period it is necessary to examine the patient, to provide the carbohydrate load 2 hours before the intervention, to conduct antibiotic prophylaxis, to correct or stabilize the comorbid diseases (especially cardiovascular and renal diseases, diabetes, anemia). In the intraoperative period it is necessary to maintain normovolemia and normothermia, to use protective mechanical lung ventilation, to limit the use of opioids, to perform extubation immediately after the intervention. In the postoperative period early activation, early enteral nutrition and early removal of drainages and catheters should be used. The key components of POM include the identification of low-risk patients in order to save resources, the identification of high-risk patients with the possible use of alternative management strategies, and the frequent risk reassessment. The main components of the success of anesthesia include preoperative assessment of the patient’s somatic status and risk, use of controlled hypnotics and effective and predictable muscle relaxant, use of analgesics that break down quickly and have no ability to accumulate, control of the hemodynamics stability, blood gases and acid-base balance. To prevent the perioperative myocardial ischemia, it is advisable to use esmolol – a cardioselective β-blocker of ultrashort action. Preoperative anxiety, intubation and extubation, surgical manipulations lead to the excessive adrenergic response, which justifies the use of β-blockers. The pharmacological effects of esmolol (Biblok, “Yuria-Pharm”) include the reduction of myocardial oxygen consumption, increase of the diastole duration, limitation of the free radicals’ production, control of the activity of metalloproteinases, and the reduction of inflammation around atherosclerotic plaques. In addition, esmolol (Biblok) is able to reduce intra- and postoperative use of opioids, and therefore its use as a component of multimodal total intravenous anesthesia has been proposed. Preoperative administration of esmolol may also be an effective and safe method of myocardial protection in patients undergoing cardiac surgery. β-blockers are well tolerated in patients with acute hypovolaemia during anesthesia, however, episodes of hypercapnia should be avoided during their use.&#x0D; Conclusions. 1. For the optimal POM, the individual risk of perioperative complications should be determined. 2. POM includes a number of pre-, intra- and postoperative measures. 3. The use of ultrashort-acting β-blocker esmolol prevents intraoperative myocardial ischemia, has antioxidant and anti-inflammatory effects, reduces the need for opioids.

Coffee, Cigarettes, Chewing Gum - Myths and Facts About Preoperative Fasting

Consumption of clear liquids (including coffee and orange juice without pulp) up to 2 hours before the start of anaesthesia is unproblematic. Contrary to the recommendations of the professional societies, the intake of beverages containing milk (up to 50% of the total volume) in small quantities seems to be harmless. Drinks containing alcohol can considerably delay emptying of the stomach. Immediate preoperative nicotine consumption has no influence on the risk of aspiration, but short-term nicotine abstinence in patients with CHD can reduce the risk of intraoperative myocardial ischaemia. Chewing gum has no effect on the pH of gastric juice, but the gastric fluid volume is slightly increased. Cancelling surgery because of preoperative chewing of gum by a patient is not justified despite increased gastric fluid volume.

I.V. NIRS off-pump coronary artery ischemia monitoring bypass surgery

Background: Spectroscopic data were compared with hemodynamic parameters, electrocardiogram, transesophageal echocardiography and laboratory findings. A conversion to extracorporeal circulation was not necessary. The mean number of grafts per patient was 3.1±0.6. An intraoperative myocardial ischemia was not evident, as indicated by electrocardiogram and transesophageal echocardiography.Methods: Continuous spectroscopic analysis showed reproducible absorption spectra of coronary sinus blood. Due to uneventful intraoperative courses, clear ischemia-related changes could be detected in none of the patients. Present initial results show that intravascular near-infrared spectroscopy can reliably be used for an online intraoperative ischemia monitoring in off-pump coronary artery bypass surgery.Results: In 15 elective patients undergoing off-pump myocardial revascularization, intravascular near-infrared spectroscopic analysis of coronary venous blood was performed. NIR signals were transferred through a fiberoptic catheter for signal emission and collection. For data analysis and processing, a miniature spectrophotometer with multivariate statistical package was used. Signal acquisition and analysis were performed before and after revascularization. However, the method has to be further evaluated and standardized to determine the role of spectroscopy in off-pump coronary artery bypass surgery. In off-pump coronary artery bypass surgery, manipulations on the beating heart can lead to transient interruptions of myocardial oxygen supply, which can generate an accumulation of oxygen-dependent metabolites in coronary venous blood.Conclusions: The objective of this study was to evaluate the reliability of intravascular near-infrared spectroscopy as a monitoring method to detect possible ischemic events in off-pump coronary artery bypass procedures.

Results of early laparoscopic cholecystechtomy in patients with acute calculous cholecystitis and concomitant ischemic heart disease

The aim — to evaluate the results of early laparoscopic cholecystectomy (LC) in patients with acute calculous cholecystitis (АСС) and concomitant ischemic heart disease.Materials and methods. The study included 107 patients with ACC: 56 (47.7 %) women and 51 (52.3 %) men aged 55 to 82 years old, on average 70.2 ± 0.6 years, treated at the surgical department. All patients were hospitalized within 29.9 ± 1.4 hours. Among all patients with angina pectoris 93 (86.9 %) had stable variant, 14 (13.1 %) — unstable, 6 (6.5 %) patients have had I class of stable angina pectoris, II class have had 45 (48.4 %), III class — 31 (33.3 %), IV class — 11 (11.8 %) of patients. According to NYHA classification, functional class of chronic heart failure (CH) had been diagnosed in 8 (7.5 %) patients, II class — in 59 (55.1 %), III class — in 33 (30.8 %), IV class — in 7 (6.5 %) of cases. 29 (27.1 %) patients have had atrial fibrillation, including permanent form in 19 (65.5 %), paroxysmal form — in 10 (34.5 %) of patients. ESV had been reported in 5 (4.7 %) patients. According to the classification of TG13, the severity of ACC variates: I grade in 37 (34.6 %) patients, II grade — in 41 (38.3 %), and grade III — in 29 (27.1 %) of patients. Anticoagulant and antiplatelet therapy before surgery was given to 95 (88.8 %) of patients. The frequency of catarrhal, phlegmonous and gangrenous forms of LC was 46 (43.0 %), 29 (27.1 %), 32 (29.9 %), respectively. In 47 (43.9 %) of patients there was a paracystic infiltrate, in 14 (13.1 %) — paravesical abscess, in 12 (11.2 %) — local peritonitis. LC (with the creation of carboxyperitoneum 12 — 15 mm Hg) is performed on average 41.1 ± 1.3 hours from the onset of the disease. The method of choice for anesthesia was total intravenous anesthesia (TIVA) with trachea intubation and artificial lung ventilation. The study points were cardiac events in the intraoperative and early postoperative periods.Results and discussion. ECG­signs of intraoperative myocardial ischemia appeared in 23 (21.5 %) patients with duration ranged from 10 up to 25 min, on average 14.8 ± 0.7 min, systolic blood pressure (SBP) &lt; 70 mm Hg decreasing for 5 — 15 min (on average 7.7 ± 0.4 min) registered in 31 (29.0 %) patients; decreasing diastolic blood pressure &lt; 50 mm Hg — in 12 (11.2 %) patients, lasting from 5 to 15 min, on average 8.1 ± 0.4 min. Episodes of reduced saturation level occured in 50 (46.3 %) patients. Bilateral bundle branch block occurred in 9 (8.4 %) patients and atrial fibrillation paroxysms occurred in 9 (8.4 %) patients. Elevated tissue bleeding was observed in 18 (16.8 %) of patients. Stepping up in the NYHA class in the postoperative period occurred in 13 (12.1 %) patients. In this case, the intensification of heart failure occurred in 9 patients from HF II to HF III, and in 4 patients from HF III to HF IV. The deepening of HF correlated with a hemoglobin decreasing &lt; 100 g/L (r = 0.704), episodes of decreasing SBP &lt; 70 mm Hg (R = 0.569), decreased saturation (&lt; 90 %) (r = 0.547), ischemia during anesthesia (r = 0.363), duration of operation (r = 0.495), and negatively correlated with MET (r = –0.436). The ratio of chances for HF deepening in patients with destructive cholecystitis to non­destructive cholecystitis is 11.02 (95 % DM: 1.4 — 88.2). Myocardial infarction (MI) developed in 6 (5.6 %) patients (Q­infarction — in 2, and non Q­infarction — in 4). The occurrence of MI correlated significantly with the intensification of the heart failure (r = 0.438), hypercoagulation before surgery (r = 0.333) and a hemoglobin decreasing &lt; 100 g/L during the operation (r = 0.311).Conclusions. In patients with ACC and concomitant IHD, myocardial ischemia was observed in 21.5 % of patients with early LC. Blood pressure lowering: systolic (&lt; 70 mm Hg) in 29.0 %, diastolic (&lt; 50 mm Hg). Besides that, 11.2 % of patients have had reduction of saturation level (&lt; 90 %) in 46.3 %, new episodes of cardiac arrhythmia in 16.8 %, increased bleeding in 16.8 %. Intensification of HF and MI in the postoperative period occurs in 12.1 % and 5.6 % of patients, respectively. Complications for the cardiovascular system correlate with the form of ACC and its severity class (TG13), NYHA class, FC for angina pectoris, MET level, changes in the hemostatic system (hyper­ and hypocoagulation), and preliminary anticoagulant therapy.

Pro: Etomidate Is the Ideal Induction Agent for a Cardiac Anesthetic

POSTINDUCTION HYPOTENSION has been associated with increased morbidity and mortality. 1 Reich D.L. Hossain S. Krol M. et al. Predictors of hypotension after induction of general anesthesia. Anesth Analg. 2005; 101: 622-628 Crossref PubMed Scopus (396) Google Scholar Patients who experienced ≥1 5-minute episode of hypotension after induction of general anesthesia had a 13.3% increase in hospital length of stay and an 8.6% increase of death. Hypotension has been defined as a decrease in mean arterial pressure <60 mmHg or by >40% decrease from baseline. In a recent study 2 Alcock R.F. Kouzios D. Naoum C. et al. Perioperative myocardial necrosis in patients at high cardiovascular risk undergoing elective non-cardiac surgery. Heart. 2012; 98: 792-798 Crossref PubMed Scopus (54) Google Scholar in patients treated with antiplatelet agents for cardiovascular comorbidities undergoing major noncardiac surgery, intraoperative hypotension was identified as 1 of 3 independent predictors of intraoperative myocardial ischemia and necrosis assessed using postoperative troponin T levels. Given the high risk of poor outcome after postinduction and intraoperative hypotension, the ideal induction agent would avoid any major deviation from baseline hemodynamic parameters.

Recurrent intraoperative silent ST depression responding to phenylephrine

Intraoperative myocardial ischemia is attributed to decreased myocardial oxygen supply. We present an unusual case of recurrent, symptomless inferior wall ischemia in an apparently healthy male with no history of coronary artery disease after a spinal block. The recurring episodes were linked to tachycardia and presented with significant ST depression in Lead II with reciprocal elevation in lead aVL. The episodes responded to phenylephrine and subsided without residual sequelae.

Prognostic factors of atrial fibrillation following elective coronary artery bypass grafting: the impact of quantified intraoperative myocardial ischemia

BackgroundAtrial fibrillation (AF) occurs in 28-33% of the patients undergoing coronary artery revascularization (CABG). This study focuses on both pre- and peri-operative factors that may affect the occurrence of AF. The aim is to identify those patients at higher risk to develop AF after CABG.Patients and methodsTwo patient cohorts undergoing CABG were retrospectively studied. The first group (group A) consisted of 157 patients presenting AF after elective CABG. The second group (group B) consisted of 191 patients without AF postoperatively.ResultsPreoperative factors presenting significant correlation with the incidence of post-operative AF included: 1) age > 65 years (p = 0.029), 2) history of AF (p = 0.022), 3) chronic obstructive pulmonary disease (p = 0.008), 4) left ventricular dysfunction with ejection fraction < 40% (p = 0.015) and 5) proximal lesion of the right coronary artery (p = 0.023). The intraoperative factors that appeared to have significant correlation with the occurrence of postoperative AF were: 1) CPB-time > 120 minutes (p = 0.011), 2) myocardial ischemia index < 0.27 ml.m2/Kg.min (p = 0.011), 3) total positive fluid-balance during ICU-stay (p < 0.001), 4) FiO2/PO2 > 0, 4 after extubation and during the ICU-stay (p = 0.021), 5) inotropic support with doses 15-30 μg/Kg/min (p = 0.016), 6) long ICU-stay recovery for any reason (p < 0.001) and perioperative myocardial infarction (p < 0.001).ConclusionsOur results suggest that the incidence of post-CABG atrial fibrillation can be predicted by specific preoperative and intraoperative measures. The intraoperative myocardial ischemia can be sufficiently quantified by the myocardial ischemia index. For those patients at risk we would suggest an early postoperative precautionary anti-arrhythmic treatment.

Recurrent ST-segment elevation on ECG and ventricular tachycardia during neurosurgical anesthesia

This article reports an unusual case of repeated intraoperative myocardial ischemia and ventricular arrhythmia during neurosurgical anesthesia. The presentation was clinically diagnosed as coronary spasm after successful resuscitation. Intraoperative prostaglandin E(1) and beta-adrenergic blockade, as well as vagal stimulation due to surgical manipulation, may have contributed to the episode.

Intraoperative myocardial ischemia during renal transplantation caused by anomalous origin of the right coronary artery

Anomalous origin of the right coronary artery (AORCA) is a rare congenital anomaly with an incidence of 0.92% during routine cardiac catheterization. Its presence raises an important concern to the anaesthesiologist because it can lead on to myocardial ischaemia manifesting as either angina pectoris or myocardial infarction, or sudden death in young patients with minimal exertion, even in the absence of atherosclerosis. Patients with AORCA may be intolerant to stress and the high cardiac output condition owing to volume loading. Such a therapeutic manoeuvre may be desirable during renal transplantation to enable better perfusion of the renal graft immediately after grafting the kidney, in order to improve its function. Hence, haemodynamic goals in renal transplant recipient with AORCA can be contradictory during surgery, thereby rendering anaesthetic management challenging. We report a case of acute myocardial ischemia precipitated by fluid loading conditions in a patient with AORCA during renal transplant that was successfully treated with emergent intra-aortic balloon pump therapy intraoperatively. Judicious intraoperative fluid replacement is recommended, and volume overload must be avoided in AORCA patients undergoing surgery.

Intra-operative myocardial ischaemia cannot be detected by analysis of transmitral inflow patterns in patients undergoing off-pump coronary surgery

Transmitral inflow patterns have been used for detection of myocardial ischaemia. However, its diagnostic value has not been tested in anaesthetized and mechanically ventilated patients undergoing coronary artery bypass graft surgery. Transmitral inflow patterns were studied by transoesophageal Doppler echocardiography in 43 patients undergoing coronary artery bypass graft surgery without cardiopulmonary bypass after opening of the sternum (baseline) and during grafting of the left anterior descending artery. Peak early (E) and peak late (A) transmitral velocities and their ratio (E/A) were recorded. Myocardial ischaemia was defined by standard criteria using two-dimensional echocardiography and seven-lead electrocardiogram. Thirty-one patients (64 +/- 8 yr, 9 women) fulfilled the predefined inclusion criteria for analysis. During distal revascularization, 16 patients showed myocardial ischaemia and 15 did not. The use of vasoactive drugs, haemodynamic findings and transmitral inflow patterns were similar in both groups at baseline and during grafting. In the ischaemic group, E was 67.1 +/- 13.9 cm s-1 at baseline and 69.5 +/- 23.2 cm s-1 during grafting, and the E/A ratios were 1.3 +/- 0.3 and 1.4 +/- 0.9, respectively. In the non-ischaemic group, E was 64.0 +/- 17.1 cm s-1 at baseline and 60.9 +/- 14.8 cm s-1 during grafting, and the E/A ratios were 1.4 +/- 0.7 and 1.2 +/- 0.3, respectively. Analysis of Doppler findings of transmitral inflow patterns did not allow for detection of myocardial ischaemia during surgical revascularization of the myocardium.

Intraoperative myocardial ischemia in peripheral vascular surgery: general anesthesia vs combined sciatic and femoral nerve blocks

Intraoperative myocardial ischemia in peripheral vascular surgery: general anesthesia vs combined sciatic and femoral nerve blocks

Meetings of Interest

: The intravascular application of near-infrared spectroscopy was previously evaluated in acute ischemia-reperfusion studies in animal experiments. The objective of our study was to assess the technical feasibility and clinical reliability of an online myocardial ischemia monitoring by using intravascular near-infrared spectroscopy during off-pump coronary bypass surgery. : Intravascular near-infrared spectroscopy of coronary sinus blood was performed in 10 elective patients selected for off-pump coronary bypass surgery. Light signals were transferred through a fiberoptic catheter for emission and collection from the coronary sinus blood. Spectrometric analyses were performed before and after revascularization with internal thoracic artery and saphenous vein grafts. Changes in spectroscopic data were compared with hemodynamic parameters and electrocardiographic, transesophageal echocardiographic, and laboratory findings. : All of the operations were finished as off-pump procedures. No remarkable intraoperative myocardial ischemia was observed in the patient group, as indicated by electrocardiography and transesophageal echocardiography. Reproducible absorption spectra of coronary sinus blood were obtained at every defined step of the surgical procedure. Clear ischemia-related changes were detected in none of the patients. : Our initial results showed that intravascular near-infrared spectroscopic ischemia monitoring is technically feasible. However, the method must be further evaluated and standardized under varying conditions to determine the role of near-infrared spectroscopy as an ischemia monitoring tool in off-pump coronary bypass surgery.

Segmental Wall-Motion Abnormalities After an Arterial Switch Operation Indicate Ischemia

We prospectively studied 29 consecutive neonates undergoing an arterial switch operation to determine if segmental wall motion abnormalities (SWMA) represented myocardial ischemia. Intraoperative transesophageal echocardiogram was recorded at baseline and twice after cardiopulmonary bypass. Cardiac troponin I (cTnI) levels were measured before sternal incision and 3, 6, 12, 24, 48, and 72 h after removal of the aortic cross-clamp. Immediate postoperative Holter and 15-lead electrocardiograms (ECG) were evaluated for ischemia. Transthoracic echocardiograms were obtained before hospital discharge. At bypass termination, immediately after protamine administration, segmental wall motion was normal in nine neonates and abnormal in 20. SWMA were transient in five and present at the time of chest closure in 15 neonates. Neonates in whom SWMA were present at chest closure had more segments involved than those in whom SWMA were transient (P > 0.001). Neonates with SWMA at chest closure had higher cTnI levels postoperatively versus neonates with normal wall motion (P = 0.02). Postoperative ECG data were available in 26 neonates. There was ECG evidence of myocardial ischemia in two of eight neonates with normal wall motion, one of five with transient SWMA, and nine of 13 with SWMA at chest closure. CTnI levels at 12, 24, and 48 h and intraoperative SWMA were predictive of postoperative SWMA. We believe these data indicate that SWMA, which persist at the completion of an arterial switch operation, and which are present in multiple myocardial segments, correlate with myocardial ischemia. Further follow-up of these patients is needed to determine if increased intraoperative myocardial ischemia correlates with long-term outcomes.

Vacuum-assisted apical suction devices induce passive electrical changes consistent with myocardial ischemia during off-pump coronary artery bypass graft surgery

Off-pump coronary artery bypass graft surgery is common therapy to completely revascularize diseased hearts. In order to graft posterior arteries in this procedure, the heart must be lifted from the chest cavity and manipulated to expose the surgical field using an apical suction device. This suction device may cause unwanted myocardial ischemia. In this observational study, we measured myocardial electrical impedance, a parameter that responds to myocardial ischemia, as well as ST-segment changes during off-pump coronary artery bypass graft surgery in 12 patients with two-vessel coronary artery disease undergoing revascularisation of the left anterior descending and the posterior descending coronary arteries. During the posterior descending artery revascularisation phase of the procedure the apical suction device was oriented over the electrodes used to measure myocardial electrical impedance, thus allowing us the opportunity to assess myocardial ischemia in this region of the heart. In these 12 patients, myocardial electrical impedance progressively increased under the suction device during posterior coronary artery revascularisation, suggesting that myocardial ischemia developed in this region of the myocardium. ST-segment changes were negligible while the heart was vertically displaced (and the suction device attached), but increased immediately when the heart was returned to the neutral anatomical position. Our data suggest that the apical suction device may cause ischemia while the heart is vertically displaced and electrically disconnected from the body. Under these conditions, ST-segment changes may not detect myocardial ischemia. Myocardial electrical impedance has the potential to reliably detect intraoperative myocardial ischemia under these circumstances.

Feasibility of Intravascular Near-Infrared Spectroscopy in Off-Pump Myocardial Revascularization

: The intravascular application of near-infrared spectroscopy was previously evaluated in acute ischemia-reperfusion studies in animal experiments. The objective of our study was to assess the technical feasibility and clinical reliability of an online myocardial ischemia monitoring by using intravascular near-infrared spectroscopy during off-pump coronary bypass surgery. : Intravascular near-infrared spectroscopy of coronary sinus blood was performed in 10 elective patients selected for off-pump coronary bypass surgery. Light signals were transferred through a fiberoptic catheter for emission and collection from the coronary sinus blood. Spectrometric analyses were performed before and after revascularization with internal thoracic artery and saphenous vein grafts. Changes in spectroscopic data were compared with hemodynamic parameters and electrocardiographic, transesophageal echocardiographic, and laboratory findings. : All of the operations were finished as off-pump procedures. No remarkable intraoperative myocardial ischemia was observed in the patient group, as indicated by electrocardiography and transesophageal echocardiography. Reproducible absorption spectra of coronary sinus blood were obtained at every defined step of the surgical procedure. Clear ischemia-related changes were detected in none of the patients. : Our initial results showed that intravascular near-infrared spectroscopic ischemia monitoring is technically feasible. However, the method must be further evaluated and standardized under varying conditions to determine the role of near-infrared spectroscopy as an ischemia monitoring tool in off-pump coronary bypass surgery.

Ischemia monitoring in off-pump coronary artery bypass surgery using intravascular near-infrared spectroscopy.

BackgroundIn off-pump coronary artery bypass surgery, manipulations on the beating heart can lead to transient interruptions of myocardial oxygen supply, which can generate an accumulation of oxygen-dependent metabolites in coronary venous blood. The objective of this study was to evaluate the reliability of intravascular near-infrared spectroscopy as a monitoring method to detect possible ischemic events in off-pump coronary artery bypass procedures.MethodsIn 15 elective patients undergoing off-pump myocardial revascularization, intravascular near-infrared spectroscopic analysis of coronary venous blood was performed. NIR signals were transferred through a fiberoptic catheter for signal emission and collection. For data analysis and processing, a miniature spectrophotometer with multivariate statistical package was used. Signal acquisition and analysis were performed before and after revascularization. Spectroscopic data were compared with hemodynamic parameters, electrocardiogram, transesophageal echocardiography and laboratory findings.ResultsA conversion to extracorporeal circulation was not necessary. The mean number of grafts per patient was 3.1 ± 0.6. An intraoperative myocardial ischemia was not evident, as indicated by electrocardiogram and transesophageal echocardiography. Continuous spectroscopic analysis showed reproducible absorption spectra of coronary sinus blood. Due to uneventful intraoperative courses, clear ischemia-related changes could be detected in none of the patients.ConclusionOur initial results show that intravascular near-infrared spectroscopy can reliably be used for an online intraoperative ischemia monitoring in off-pump coronary artery bypass surgery. However, the method has to be further evaluated and standardized to determine the role of spectroscopy in off-pump coronary artery bypass surgery.

Intraoperative myocardial ischemia in peripheral vascular surgery: general anesthesia vs combined sciatic and femoral nerve blocks

Study Objective The aim of this study was to compare the frequency of intraoperative myocardial ischemia in lower extremity vascular surgery with general anesthesia vs regional anesthesia via combined sciatic and femoral nerve blocks. Design This is a prospective, randomized study. Setting This study was set at an academic medical center. Patients The study included 50 patients scheduled for elective lower extremity vascular surgery. Interventions Patients in group 1 received balanced general anesthesia, whereas patients in group 2 received combined sciatic and femoral nerve blocks with 40 mL of 0.375% bupivacaine. Monitoring included a radial artery catheter and multilead, dual-channel electrocardiogram with computerized ST-segment analysis. Blood pressure and heart rate variations were maintained within 10% of preoperative values by adjusting anesthetic depth, fluid replacement, and vasoactive drug dosages. Measurements and Main Results An ST-segment depression of at least 1 mm or elevation of at least 2 mm lasting for more than 1 minute was considered a significant episode of myocardial ischemia. Intraoperative hemodynamic data and the frequency of significant ST-segment change episodes were recorded. The number of patients with ischemic episodes and the total number of these episodes were lower in group 2 than in group 1 (1 patient vs 7 patients, P = 0.02; and 2 vs 14 episodes, P = 0.04). No significant difference was found between groups 1 and 2 regarding systolic or diastolic arterial pressures, or heart rate. Conclusion Compared with general anesthesia, combined sciatic and femoral nerve blocks reduce the frequency of intraoperative myocardial ischemia in patients undergoing lower extremity vascular surgery.

On-pump beating heart versus off-pump coronary artery bypass surgery—evidence of pump-induced myocardial injury

By maintaining native coronary blood flow in on-pump beating heart surgery (OnP-BH) and comparing with OPCAB strategy pump-related effects on myocardial injury and cardiac dysfunction could be specifically differentiated from ischemia/reperfusion-related consequences of surgical coronary revascularization. In a randomized-prospective design, 40 elective patients with normal EF and three vessels coronary artery disease (left main disease excluded) were assigned to OPCAB or OnP-BH surgery. Before coronary occlusion and 1, 30, 60, and 90 min after reperfusion with the LIMA graft, coronary sinus (CS) blood was sampled to determine intraoperative myocardial ischemia (pH, lactate, pO2) and oxidative stress (malondialdehyde, MDA). Additionally to CS blood arterial blood was analyzed 4, 12, and 24 h postoperatively to determine myocardial necrosis (CK-MB, cardiac troponin I), myocardial dysfunction (NT-proBNP) and inflammation (C-reactive protein). Groups were identical with regards to age and gender (OPCAB 63.0+/-6.0 versus OnP-BH 65.3+/-3.9 y, 20% female patients). Number of grafts were 3.0+/-0.5 in OPCAB versus 2.9+/-0.3 in OnP-BH (n.s.) with 44 versus 34% bilateral IMAs and 56 versus 50% complete arterial revascularization. Regarding ischemia, intraoperatively only lactate values increased significantly in the OnP-BH group. Significantly higher CK-MB and troponin I levels were found from LIMA-LAD flow release onwards to 4 h postoperatively in the OnP-BH group. NT-proBNP levels were significantly higher in the OnP-BH group during the entire study period. CRP levels were higher in the OnP-BH group 12 and 24 h postoperatively. In this randomized study on routine coronary patients with normal ventricular function, OPCAB revealed less myocardial injury than OnP-BH. These findings implicate that CPB slightly affects the myocardium.