Celebrating the 100th birthday of the electrocardiogram: lessons learned from research in cardiac monitoring.

The electrocardiogram continues to be the gold standard for the diagnosis of cardiac arrhythmias and acute myocardial ischemia. The treatment of arrhythmias in critical care units has become less aggressive during the past decade because research indicates that antiarrhythmic agents can be proarrhythmic, causing malignant ventricular arrhythmias such as torsade de pointes. However, during the same period, the treatment of acute myocardial ischemia has become more aggressive, with the goal of preventing or interrupting myocardial infarction by using new antithrombotic and antiplatelet agents and percutaneous coronary interventions. For this reason, critical care nurses should learn how to use ST-segment monitoring to detect acute ischemia, which is often asymptomatic, in patients with acute coronary syndromes. Because the electrocardiographic lead must be facing the localized ischemic zone of the heart to depict the telltale signs of ST-segment deviation, the challenge is to find ways to monitor patients continuously for ischemia without using an excessive number of electrodes and lead wires. The current trend is to use reduced lead set configurations in which 5 or 6 electrodes, placed at convenient places on the chest, are used to construct a full 12-lead electrocardiogram. Nurse scientists at the University of California, San Francisco, School of Nursing are at the forefront in developing and assessing the diagnostic accuracy of these reduced lead set electrocardiograms.     

Interpreting 12-lead electrocardiograms for acute ST-elevation myocardial infarction: what nurses know

In patients with acute myocardial infarction, early reperfusion and sustained patency of the culprit artery are important determinants of survival. The 12-lead electrocardiogram (ECG) is considered the noninvasive gold standard for identification of acute ST-elevation myocardial infarction. Nurses play a critical role in the process of obtaining, interpreting, and communicating ECG findings. This study evaluates nurses' ability to differentiate ischemic from nonischemic ECG patterns, to detect affected ECG leads and location of ischemia, and assesses skill level by hospital unit type. Seventy-five nurses were given a set of 6 patient scenarios, each with a corresponding 12-lead ECG, and asked to identify the presence or absence of ischemia. Fourteen (19%) of the 75 nurses correctly identified the presence or absence of ischemia in all 6 scenarios. Of the 3 ECGs with a myocardial infarction pattern, 59 (79%) of the nurses identified all 3 as ischemic; however, no one was able to determine the correct leads, location, or amplitude of ST-segment elevation. For the 3 nonischemic ECGs, 37 (49%) of the nurses identified a normal ECG as ischemic, 47 (63%) determined that an early repolarization pattern was ischemic, and 34 (45%) indicated that a left bundle branch block pattern was ischemic. These results not only identify educational opportunities but also provide important information for researchers implementing clinical trials evaluating the use of bedside ECG monitoring systems for detection of acute myocardial ischemia.     

ST-segment monitoring: putting standards into practice

ST-segment monitoring is one key reason that continuous electrocardiographic monitoring is performed in hospitals, and can help with early detection of myocardial ischemia for at-risk patients. Although ST-segment monitoring research, guidelines, and expert consensus statements have been published, ST-segment monitoring has not been implemented in all appropriate clinical areas. The purpose of this article is to present relevant research, review the latest practice standards, and discuss issues important to nurses wishing to implement ST-segment monitoring.     

Impact of Pulmonary Hypertension on In-Hospital Outcomes and 30-Day Readmissions Following Percutaneous Coronary Interventions

ObjectiveTo evaluate the impact of pulmonary hypertension (PH) on percutaneous coronary intervention (PCI) outcomes and 30-day all-cause readmissions by analyzing a national database.MethodsWe queried the 2014 National Readmissions Database to identify patients undergoing PCI using International Classification of Diseases, Ninth Revision, Clinical Modification codes. These patients were then subcategorized based on the coded presence or absence of PH and further analyzed to determine the impact of PH on clinical outcomes, health care use, and 30-day readmissions.ResultsAmong 599,490 patients hospitalized for a PCI in 2014, 19,348 (3.2%) had concomitant PH. At baseline, these patients were older with a higher burden of comorbidities. Patients with PH had longer initial hospitalizations and higher 30-day readmission rates and mortality than their non-PH counterparts. This was largely driven by cardiac causes, most commonly heart failure (20.3% vs 9.0%, P<.001) and non–ST-segment elevation myocardial infarction. Recurrent coronary events (17.5% vs 9.5%, P<.05) including ST-segment elevation myocardial infarction predominated in the non-PH group.ConclusionPatients with PH undergoing PCI are a high-risk group in terms of mortality and 30-day readmission rates. Percutaneous coronary intervention in patients with PH is associated with higher rates of recurrent heart failure and non–ST-segment elevation myocardial infarction, rather than recurrent coronary events or ST-segment elevation myocardial infarction. This perhaps indicates a predominance of demand ischemia and heart failure syndromes rather than overt atherothrombosis in the etiology of chest pain in these patients.     

Survey of use of ST-segment monitoring in patients with acute coronary syndromes.

BACKGROUND: Although effective for assessing ongoing myocardial ischemia, ST-segment monitoring may be underused. OBJECTIVES: To determine the proportion of cardiac units in the United States that use ST-segment monitoring, hospital and unit characteristics associated with its use, how units use such monitoring with respect to research recommendations, if units that use ST-segment monitoring find it clinically useful and easy to use, and why some units are not using this type of monitoring. METHODS: A survey on ST-segment monitoring was mailed to a random sample of 500 cardiac nurse managers and clinical nurse specialists. RESULTS: Of the final 192 respondents, 104 (54.2%) reported that they were using ST-segment monitoring. Monitor brand was the only characteristic associated with use of this monitoring (P = .03). On units that used ST-segment monitoring, patients were monitored if they had myocardial infarction (81%), unstable angina (79.6%), or possible myocardial infarction (78.6%) and after percutaneous transluminal coronary angioplasty (47.6%). Leads were chosen according to unit protocol (60.2%) and 12-lead electrocardiographic findings (48.5%); leads II (95.0%) and V1 (75.2%) were used most often. The majority of units that use ST-segment monitoring agreed that it is clinically useful (83%) and easy to use (56%). Among the units not using ST-segment monitoring, the most common reason was that physicians were not interested (27.1%). CONCLUSIONS: ST-segment monitoring is not routinely used; when it is, research recommendations are often not followed. Increased awareness is needed among cardiac nurses and physicians of the clinical usefulness and proper use of ST-segment monitoring.     

冠心病患者动态心电图监测的研究

目的：研究动态心电图对冠心病患监测的价值。方法：对276例冠心病患进行24—72h的动态心电图监测并与常规心电图结果进行对比分析。结果：动态心电图对冠心病患的心律失常检出率达100％，无症状心肌缺血检出率为26．80％，明显高于常规心电图的检出率(61％及5．80％)。结论：动态心电图能及时发现冠心病患的各种心率失常和无症状心肌缺血，对于预防和防止急性心梗和心源性猝死较常规心电图更可靠。     

238例高龄冠心病患者PCI术前后动态心电图分析

目的探讨高龄冠状动脉粥样硬化性心脏病患者PCI术后心肌再缺血情况与临床表现以及心律失常的关系。方法对238例〉70岁老年患者成功行PCI手术前后的临床表现及24h动态心电图结果进行比较分析。结果238例老年冠心病患者术后动态心电图显示24h心肌缺血发作次数、ST段压低幅度、ST段压低总时间、缺血发作平均时间和心脏事件发生率明显低于手术前[分别为（4．2±1．2）次与（9．3±1．7）次;（1．4±0．5）mm与（3．4±0．4）mm;（28．3±5．6）min与（207．5±13．2）min;（4．8±0．9）min与（19．2±2．2）min和25．1％与66．4％],差异有统计学意义（P值均〈0．001）。动态心电图记录到的心肌缺血发作时,临床发生典型心绞痛症状的比例明显低于手术前（为7．6％vs43．8％,P〈0．001）,传导阻滞发生率无显著变化（P〉0．05）。结论成功的PCI手术能明显改善冠心病患者心肌缺血发作次数、缺血程度及持续的时间、严重心律失常的发作次数,缓解心绞痛症状;但对已存在的传导阻滞改善不明显。动态心电图可作为一种对PCI术后疗效及患者预后有价值、无创性的评价方法。     

Continuous ST-segment monitoring: raising the bar

ST-segment monitoring is recommended by clinical experts to assist in the early detection of transient myocardial ischemia; however, a gap exists between the recommendations and clinical practice. This article provides a review of research to support the use of ST-segment monitoring in a variety of clinical situations. Patient selection for monitoring, techniques, and strategies to facilitate successful implementation of ST monitoring are included. Nurses are encouraged to advocate for patients by raising the bar of electrocardiogram monitoring practice to aid in optimizing patient outcomes.     

Chest pain showing precordial ST-segment elevation in a 96-year-old woman with right coronary artery occlusion: A case report

BACKGROUNDTypically, right coronary artery (RCA) occlusion causes ST-segment elevation in inferior leads. However, it is rarely observed that RCA occlusion causes ST-segment elevation only in precordial leads. In general, an electrocardiogram is considered to be the most important method for determining the infarct-related artery, and recognizing this is helpful for timely discrimination of the culprit artery for reperfusion therapy. In this case, an elderly woman presented with chest pain showing dynamic changes in precordial ST-segment elevation with RCA occlusion.CASE SUMMARYA 96-year-old woman presented with acute chest pain showing precordial ST-segment elevation with dynamic changes. Myocardial injury markers became positive. Coronary angiography indicated acute total occlusion of the proximal nondominant RCA, mild atherosclerosis of left anterior descending artery and 75% stenosis in the left circumflex coronary artery. Percutaneous coronary intervention was conducted for the RCA. Repeated manual thrombus aspiration was performed, and fresh thrombus was aspirated. A 2 mm × 15 mm balloon was used to dilate the RCA with an acceptable angiographic result. The patient’s chest pain was relieved immediately. A postprocedural electrocardiogram showed alleviation of precordial ST-segment elevation. The diagnosis of acute isolated right ventricular infarction caused by proximal nondominant RCA occlusion was confirmed. Echocardiography indicated normal motion of the left ventricular anterior wall and interventricular septum (ejection fraction of 54%), and the right ventricle was slightly dilated. The patient was asymptomatic during the 9-mo follow-up period.CONCLUSIONCardiologists should be conscious that precordial ST-segment elevation may be caused by occlusion of the nondominant RCA.     

Improving the safety of oxygen therapy in the treatment of acute myocardial infarctions

AimThe article examines the evidence for giving oxygen routinely to patients with suspected myocardial infarction, and addresses the challenges in changing practice.BackgroundIt has been thought that administering oxygen to patients suffering from acute myocardial infarctions may be beneficial, but there is a lack of supporting evidence. Furthermore there is evidence that the use of oxygen in some circumstances may not improve clinical outcome. Despite conflicting evidence, guidelines in the past have recommended supplementary oxygen as part of treatment. Therefore it was necessary to understand and identify best practice.MethodsEvidence was collated using electronic databases. Search terms included ‘acute myocardial infarction’ ‘acute coronary syndrome’ ‘oxygen’ and ‘hypoxia’, ‘hyperoxaemia’.ConclusionA systematic review of studies did not confirm that the use of routine oxygen in the acute stages of a myocardial infarction reduces myocardial ischemia. In reality, some evidence suggests that oxygen may even increase myocardial ischemia. Therefore it is crucial that emergency care nurses/practitioners across the world use observation skills and monitoring such as pulse oximetry to recognise the clinical need for supplementary oxygen to be given to a patient.     

Factors to consider when analyzing 12-lead electrocardiograms for evidence of acute myocardial ischemia.

An important factor to consider when using findings on electrocardiograms for clinical decision making is that the waveforms are influenced by normal physiological and technical factors as well as by pathophysiological factors. Traditionally, the focus of bedside monitoring is detection of arrhythmia. However, continuous ST-segment monitoring for the detection of myocardial ischemia is now readily available. Many factors affect electrocardiographic waveforms and may interfere with diagnosis of myocardial ischemia based on electrocardiographic findings. Accordingly, a principal leadership role for clinical nurse specialists and nurse practitioners is to become knowledgeable about interpretation of 12-lead electrocardiograms and to share this knowledge with staff nurses who care for patients with acute coronary syndromes. The factors that alter electrocardiographic findings are reviewed, and the alterations that interfere with electrocardiogram-based diagnosis of myocardial ischemia are discussed.     

Early CK-MB Elevations Predict Ischemic Events in Stable Chest Pain Patients

ABSTRACT Objective : To demonstrate that creatine kinase-MB fraction (CK-MB) elevations within three hours of presentation in the emergency department (ED) are associated with subsequent ischemic events in clinically stable chest pain patients. Methods : Prospective cohort study at two university-affiliated teaching hospitals. Participants were consenting ED chest pain patients 25 years old or older without evidence of rhythm or hemodynamic instability (n = 449). Exclusions included ST-segment elevation ≥0.1 mV in ≥2 electrocardiogram leads, chest wall trauma, abnormal x-ray studies, and incomplete data collection. Measurements included presenting and three-hour CK-MB levels, presenting ECG, initial clinical impression of coronary care unit need, and clinical follow up. Monitored adverse events included myocardial ischemia necessitating coronary angioplasty or cardiac bypass surgery, recurrent in-hospital myocardial infarction, bradycardia requiring pacing, emergent cardioversion, cardiogenic shock, ventricular fibrillation, and death. Results : Overall, nine (2%) of 449 patients experienced an ischemic event within the first 48 hours. All nine patients required either coronary angioplasty or bypass surgery. Four (44%) of the nine patients with 48-hour ischemic events had elevated CK-MB levels. Of 23 patients who had complications within one week of ED presentation, seven (30%) had elevated ED CK-MB levels. An elevated CK-MB level was associated with an ischemic event both within 48 hours (risk ratio 9.5; 95% CI 2.7–33.7) and within one week (risk ratio 5.2; 95% CI 2.3–11.7). Conclusions : An elevated CK-MB level within three hours of ED presentation is associated with a subsequent ischemic event in the clinically stable chest pain patient without ST-segment elevation. However, the ED CK-MB identifies only a minority of otherwise low-risk patients who develop ischemic events; other markers for diagnosing myocardial ischemia in the ED are needed.     

Rest myocardial perfusion imaging: a valuable tool in ED

BackgroundAcute chest pain is a frequent cause of emergency department (ED) visits. Rest myocardial perfusion imaging (RMPI) during or immediately after an episode of chest pain can provide diagnostic and prognostic information concerning acute coronary syndromes.AimOur purpose was to evaluate the RMPI score in risk stratification of chest pain suspected to be of cardiac ischemic origin and negative troponin assessment.MethodsNinety-six patients without an ongoing myocardial infarction or a history of coronary artery disease and in whom RMPI was performed in the ED because of chest pain suspected to be related with acute myocardial ischemia were included.Follow-up was performed considering the occurrence of death, myocardial infarction, or revascularization in a 12-month period admission.ResultsFourteen (14.6%) patients had events. According to survival analysis, the variables related with events were a history of angina (hazard ratio [HR], 4.5; P ≤ .01), an ischemic electrocardiogram (HR, 4.0; P ≤ .01), the abnormal RMPI (HR, 11.4; P ≤ .05), and the RMPI score (HR, 1.1; P ≤ .0001). When the variables of interest were forced into a multivariate model, the χ² associated with the model that includes clinical and electrocardiogram information was 16.3 (P ≤ .005) and in the model that also includes RMPI score, it was 23.0 (P ≤ .0005).ConclusionIn a low- to intermediate-risk group of patients with suspected acute myocardial ischemia, RMPI gives not only diagnostic information but adds prognostic value to the traditional ED risk stratification tools.     

Sensitivity of routine intensive care unit surveillance for detecting myocardial ischemia

OBJECTIVE: To assess the effectiveness of routine intensive care unit surveillance compared with frequent 12-lead electrocardiogram monitoring for detecting electrocardiogram evidence suggestive of prolonged myocardial ischemia in vascular surgery patients. DESIGN: Prospective cohort trial. SETTING: Intensive care unit. PARTICIPANTS: We studied 149 patients undergoing elective infrainguinal or aortic vascular surgery who were admitted to the intensive care unit postoperatively. INTERVENTIONS: Patients were simultaneously monitored with a 10-electrode/12-lead electrocardiogram obtained every 2 mins (criterion standard) and routine intensive care unit surveillance that included standard monitoring (five-electrode/two-lead electrocardiogram with ST segment trends and routine 12-lead electrocardiogram) and clinical assessment for detecting myocardial ischemia. The results of the criterion standard were not available to the caregivers. MEASUREMENTS AND MAIN RESULTS: We measured the ability of routine intensive care unit surveillance to detect the first 20 mins of electrocardiogram evidence suggestive of myocardial ischemia, defined as ST segment depression or elevation of >/=1 mm in two consecutive leads, during the first postoperative day. Seventeen patients (11%) had electrocardiogram evidence suggestive of prolonged myocardial ischemia, the majority of which occurred in leads V2-V4. The sensitivity of routine intensive care unit surveillance for detecting the first episode of electrocardiogram evidence suggestive of prolonged myocardial ischemia in a patient was 12% (95% confidence interval, 7-17%), and the specificity was 98% (95% confidence interval, 95-100%) with a positive predictive value of 40% (95% confidence interval, 32-48%), a negative predictive value of 90% (95% confidence interval, 85-94%), a positive likelihood ratio of 6, and a negative likelihood ratio of 1. The sensitivity of routine intensive care unit surveillance for detecting all episodes was 3% (95% confidence interval, 2-3%) and the specificity 99% (95% confidence interval, 99-100%) per 20-min monitoring interval, with a positive predictive value of 17% (95% confidence interval, 16-18%), negative predictive value of 95% (95% confidence interval, 95-96%), positive likelihood ratio of 3, and negative likelihood ratio of 1. CONCLUSIONS: Routine intensive care unit surveillance has low sensitivity for detecting electrocardiogram evidence suggestive of prolonged myocardial ischemia compared with frequent 12-lead electrocardiograms. Because detecting electrocardiogram evidence suggestive of prolonged postoperative myocardial ischemia is important, physicians should consider alternative strategies to detect myocardial ischemia.     

Factors Related to Nurses’ Knowledge and Attitudes Toward Pain in Hospitals in Low-Income Areas

BackgroundEffective pain management is closely related to nurses' knowledge and attitudes toward pain. Limited studies have been performed related to nurses’ knowledge and attitudes toward pain in hospitals in low-income areas.AimsThis study surveyed the knowledge and attitudes of nurses toward pain management in county hospitals from low-income areas in Hunan Province, China.Setting and participantsThe study included 4,668 registered nurses working in 48 county hospitals in low-income areas in China.MethodsA cross-sectional study examined the knowledge and attitudes of nurses with regard to pain using the Chinese version of the Knowledge and Attitude Survey Regarding Pain (KASRP) via the WeChat application.ResultsThe 4,668 registered nurses completed the survey; of these, 43.6% indicated they had never received continuing education for pain. The mean percentage score for KASRP was (40.3 ± 7.95), and none of the respondents achieved a percentage score of >80%. Further, of the 40 items, only two had a correct rate of >80%. Continuing pain education did not significantly affect KASRP. Multiple stepwise linear regression showed that education level, ethnicity, professional title, position, and department were independent influencing factors for KASRP scores.ConclusionAlmost all nurses in county hospitals of low-income areas had deficiencies in various aspects of pain management knowledge. Better educated nurses with higher professional title or management position, those from the Han ethnicity, and those from the oncology department had higher mean KASRP scores. Current continuing education programs for pain did not improve the pain management capability of the nurse. High-quality and standardized pain educational programs should be implemented to improve pain management.     

Computer-assisted continuous ST-segment analysis for clinical research: methodological issues

Continuous ST-segment monitoring has been used to detect acute myocardial ischemia, determine the success of the reperfusion therapy, and predict outcomes in both research and a variety of clinical settings. However, analyzing the abundant electrocardiography (ECG) data recorded using continuous multilead ST-segment monitoring techniques is time consuming and requires expertise. Experienced data interpreters in dedicated ECG core laboratories handle many continuous ECG data records from large clinical trials. Little information on measurement issues for computer-assisted ST-segment analysis is available for individual investigators. Unsupervised or inexperienced computer analysis of ST-segment deviations can, under certain circumstances, yield invalid or unreliable summary indices. The goal of this article is to discuss basic ST-segment measurement principles in evaluating acute myocardial ischemia and methodological issues surrounding the use of computer-assisted ST-segment analysis for continuous ECG data. Variables affecting ST-segment measurements will be examined. Sources and examples of variability for these potential errors will be identified.     

急性ST段抬高型心肌梗死时Ⅲ级缺血的预测和预后价值

目的探讨行直接经皮冠状动脉介入治疗（PCI）的急性ST段抬高型心肌梗死（STEMI）患者Ⅲ级缺血的预测因素和预后价值。方法入选急诊PCI的STEMI患者312例,发病时间均在12 h以内,根据入院时心电图表现分为Ⅱ级缺血组（A组,n=198）和Ⅲ级缺血组（B组,n=114）,住院期间记录一般临床资料、TIMI危险评分、ST段回降率（STR）和院内死亡率。结果与A组相比,B组患者年龄较大、左心室射血分数（EF）值低、而TIMI危险评分〉3、Killip分级〉1和前壁心肌梗死的比例大（P〈0.05）;A组患者PCI术后STR〉50%较B组显著增加（53.54%和30.70%,P〈0.05）。2组院内死亡率分别为1.52%vs.6.14%,Logistic回归分析显示院内死亡率与Ⅲ级缺血呈正相关,有统计学意义（r=1.189,P〈0.05）。结论年龄大、低EF值、TIMI危险评分〉3、Killip分级〉1和前壁心肌梗死患者易出现入院时心电图Ⅲ级缺血,且Ⅲ级缺血对患者心肌灌注不良和院内死亡率有预测价值。     

N-terminal and C-terminal fragments of IGFBP-4 as novel biomarkers for short-term risk assessment of major adverse cardiac events in patients presenting with ischemia

ObjectivesPregnancy Associated Plasma Protein A (PAPP-A)-derived N- and C-terminal fragments of IGF-binding protein-4 (NT- and CT-IGFBP-4) released from vulnerable atherosclerotic plaques are proposed to be used for cardiovascular risk assessment.Design and methodsNT- and CT-IGFBP-4 were measured by novel immunoassays in EDTA-plasma of 180 patients admitted to the emergency department with symptoms of myocardial ischemia but without ST-segment elevation. Six-month incidence of major adverse cardiac events (MACE), including myocardial infarction, cardiac death, percutaneous coronary interventions, and coronary artery bypass grafting was recorded.ResultsSixteen patients met the endpoint. NT- and CT-IGFBP-4 were strong predictors of MACE: area under ROC curve (AUC) 0.856 and 0.809, respectively. NT-IGFBP-4 concentrations ≥ 214 μg/L and CT-IGFBP-4 concentrations ≥ 124 μg/L were associated with increased risk of future MACE: adjusted hazard ratio 13.79 and 7.93, respectively.ConclusionsIGFBP-4 fragments can be utilized as biomarkers for MACE prediction in patients with suspected myocardial ischemia.     

Comparison of Electrocardiographic Recordings in Open-Chest and Closed?Chest Swine Models

The aim of our study was to compare the electrocardiographic recordings in an experimental open-chest swine model before and after left-sided thoracotomy to detect any surgery-induced fluctuations that might interfere with subsequent experimental interventions. We obtained electrocardiograms from 8 deeply anesthetized domestic swine and compared the respective ST-segment potentials obtained after vascular surgery and after left-sided thoracotomy and dissection of the left anterior descending coronary artery. Compared with baseline recordings, no significant ST-segment deviation on any of the electrocardiographic leads occurred after vascular surgery. However, statistically significant ST-segment depression was observed after thoracotomy. Invasive surgical procedures in open-chest swine models may lead to morphologic changes in the ST segment. The physiologic mechanism of these changes is not fully understood.Electrocardiography is one of the most widely used diagnostic tools in clinical practice, providing a wealth of physiologic information for cardiovascular evaluation. In addition to the routine application of electrocardiography during the examination and follow-up of patients in cardiology clinics, guidelines recommend the continuous display of the electrocardiogram during various operative procedures, allowing real-time patient assessment.^10,12 In addition, perioperative electrocardiography usually is recorded in animal models for online evaluation during experimental procedures and further computer-aided retrospective analysis if needed. A common practice in cardiovascular research is to use open-chest animal models for the investigation of cardiac pathophysiology by using electrocardiography as the primary assessment tool.^5,11,19-21Guidelines for the performance of electrocardiography have evolved little in recent years.²² Most of these guidelines formulate recommendations on the indications for electrocardiography in different patient groups and on the value of electrocardiography as a tool for preoperative risk assessment.¹⁸ More recent guidelines include recommendations for the evaluation of cardiac arrhythmias and their therapy, for risk assessment in patients with various cardiac conditions, and for the evaluation of suspected myocardial ischemia.¹⁵ Intraoperative and postoperative ST-segment monitoring can be useful in patients with known coronary artery disease or those undergoing vascular surgery, with computerized ST-segment analysis, when available, used to detect myocardial ischemia during the perioperative period.⁸ Most contemporary operating rooms and intensive care unit monitors incorporate algorithms that perform real-time analysis of the ST segment.⁸However, issues needing further research and investigation include the validation of electrocardiographic recordings, and more specifically the ST segment, in surgically manipulated cases, either in humans or experimental animals. Conventional chest wall electrocardiography is often difficult to interpret during open-chest procedures because of the altered electrical environment of the heart.²¹ Because the standards for assessment and interpretation of electrocardiography are based on the conventional noninvasive model, an important issue is to determine whether an extensive surgical procedure may potentially alter the ST-segment of electrocardiographic recordings in a manner that would necessitate additional calibration and data treatment prior to the interpretation of the recorded signals, especially in the setting of myocardial ischemia.Despite its diagnostic value, the electrocardiogram is rarely precisely regular in its morphology. Even when the cardiac electrical activity is initiated normally in the sinus node, it remains influenced by the autonomic nervous system and other biochemical conditions, which are liable to fluctuations during surgery. Consequently, accurate clinical inference based on the electrocardiogram requires that the recordings in surgically manipulated subjects correlate well with those routinely recorded in noninvasive models. We hypothesized that invasive surgical procedures applied to open-chest swine models would affect the ST segment, even in the absence of an experimental procedure inducing myocardial ischemia.