Comprehensive human cell-type methylation atlas reveals origins of circulating cell-free DNA in health and disease

Methylation patterns of circulating cell-free DNA (cfDNA) contain rich information about recent cell death events in the body. Here, we present an approach for unbiased determination of the tissue origins of cfDNA, using a reference methylation atlas of 25 human tissues and cell types. The method is validated using in silico simulations as well as in vitro mixes of DNA from different tissue sources at known proportions. We show that plasma cfDNA of healthy donors originates from white blood cells (55%), erythrocyte progenitors (30%), vascular endothelial cells (10%) and hepatocytes (1%). Deconvolution of cfDNA from patients reveals tissue contributions that agree with clinical findings in sepsis, islet transplantation, cancer of the colon, lung, breast and prostate, and cancer of unknown primary. We propose a procedure which can be easily adapted to study the cellular contributors to cfDNA in many settings, opening a broad window into healthy and pathologic human tissue dynamics.

The methylation status of circulating cell-free DNA (cfDNA) can be informative about recent cell death events. Here the authors present an approach to determine the tissue origins of cfDNA, using a reference methylation atlas of 25 human tissues and cell types, and find that cfDNA from patients reveals tissue contributions that agree with clinical findings.

Association of cardiac troponin, CK-MB, and postoperative myocardial ischemia with long-term survival after major vascular surgery

OBJECTIVES

The aim of this study was to determine the long-term prognosis with postoperative markers of myocardial ischemia and infarction.

BACKGROUND

Cardiac troponins (cTn) are superior to creatine kinase-MB fraction (CK-MB) in detecting perioperative myocardial infarction (PMI). However, their threshold levels signifying PMI and their long-term prognostic value are not yet determined.

METHODS

A cohort of 447 consecutive patients who underwent 501 major vascular procedures was prospectively studied. Perioperative continuous 12-lead electrocardiogram monitoring, cardiac troponin-I (cTn-I) and/or cardiac troponin-T (cTn-T), and CK-MB levels on the first three postoperative days, and long-term survival were determined. The association of different cutoff levels of CK-MB, troponin, and ischemia duration with long-term survival was investigated.

RESULTS

Between 14 (2.9%) and 107 (23.9%) of the patients sustained PMI, depending on the biochemical criteria used. Elevated postoperative CK-MB, cTn, and prolonged (>30 min) ischemia, at all cutoff levels examined, predicted long-term mortality independent of the preoperative predictors: patient's age, type of vascular surgery, previous myocardial infarction, and renal failure (Cox multivariate analysis). Both CK-MB >10% and cTn-I >1.5 ng/ml and/or cTn-T >0.1 ng/ml independently predicted a 3.75-fold and 2.06-fold increase in long-term mortality (p = 0.006 and 0.012, respectively). Similarly, both CK-MB >5% and cTn-I >0.6 ng/ml and/or cTn-T >0.03 ng/ml independently predicted a 2.15-fold and 1.89-fold increase in mortality (p = 0.018 and 0.01, respectively). Patients with both these markers elevated had a 4.19-fold increase in mortality (p < 0.001).

CONCLUSIONS

Postoperative CK-MB and troponin, even at low cutoff levels, are independent and complementary predictors of long-term mortality after major vascular surgery.

Diastolic dysfunction and mortality in severe sepsis and septic shock

AIMS

Systolic dysfunction in septic shock is well recognized and, paradoxically, predicts better outcome. In contrast, diastolic dysfunction is often ignored and its role in determining early mortality from sepsis has not been adequately investigated.

METHODS AND RESULTS

A cohort of 262 intensive care unit patients with severe sepsis or septic shock underwent two echocardiography examinations early in the course of their disease. All clinical, laboratory, and survival data were prospectively collected. Ninety-five (36%) patients died in the hospital. Reduced mitral annular e'-wave was the strongest predictor of mortality, even after adjusting for the APACHE-II score, low urine output, low left ventricular stroke volume index, and lowest oxygen saturation, the other independent predictors of mortality (Cox's proportional hazards: Wald = 21.5, 16.3, 9.91, 7.0 and 6.6, P< 0.0001, <0.0001, 0.002, 0.008, and 0.010, respectively). Patients with systolic dysfunction only (left ventricular ejection fraction ≤50%), diastolic dysfunction only (e'-wave <8 cm/s), or combined systolic and diastolic dysfunction (9.1, 40.4, and 14.1% of the patients, respectively) had higher mortality than those with no diastolic or systolic dysfunction (hazard ratio = 2.9, 6.0, 6.2, P= 0.035, <0.0001, <0.0001, respectively) and had significantly higher serum levels of high-sensitivity troponin-T and N-terminal pro-B-type natriuretic peptide (NT-proBNP). High-sensitivity troponin-T was only minimally elevated, whereas serum levels of NT-proBNP were markedly elevated [median (inter-quartile range): 0.07 (0.02-0.17) ng/mL and 5762 (1001-15 962) pg/mL, respectively], though both predicted mortality even after adjusting for highest creatinine levels (Wald = 5.8, 21.4 and 2.3, P= 0.015, <0.001 and 0.13).

CONCLUSION

Diastolic dysfunction is common and is a major predictor of mortality in severe sepsis and septic shock.

Importance of long-duration postoperative ST-segment depression in cardiac morbidity after vascular surgery

Major vascular surgery is associated with a high incidence of cardiac ischaemic complications. By means of continuous perioperative electrocardiographic recording, we studied 151 consecutive patients undergoing major vascular surgery to find out the characteristics of any myocardial ischaemia and the relation to outcome. 13 (8.6%) patients had postoperative cardiac events (6 myocardial infarctions, 2 unstable angina, and 5 congestive heart failure). There were 342 perioperative ischaemic episodes shown by ST-segment depression; 164 (48%) occurred postoperatively. Postoperative ischaemic episodes were significantly longer than episodes before or during operations (3.2 vs 1.7 and 1.5 min per h monitored, respectively, p < 0.001). Both Detsky's cardiac risk index and long-duration (> 2 h) preoperative ischaemia were predictive of postoperative cardiac complications (odds ratios in univariate analysis 3.3, p = 0.03, and 7.2, p = 0.009, respectively). However, long-duration (> 2 h) postoperative ischaemia was the only factor significantly associated with cardiac morbidity in multivariate logistic regression analysis (odds ratio 21.7, p = 0.001). Long-duration ST-segment depression preceded most (84.6%) postoperative cardiac events, including myocardial infarctions, and no cardiac event was preceded by ST-segment elevation. 5 of the 6 postoperative myocardial infarctions were non-Q-wave infarctions. We conclude that long-duration subendocardial ischaemia, rather than acute coronary artery occlusion, may bring about postoperative myocardial injury and complications.

Myocardial infarction after vascular surgery: the role of prolonged stress-induced, ST depression-type ischemia

OBJECTIVES

The goal of this study was to investigate the nature of the association between silent ischemia and postoperative myocardial infarction (PMI).

BACKGROUND

Silent ischemia predicts cardiac morbidity and mortality in both ambulatory and postoperative patients. Whether silent stress-induced ischemia is merely a marker of extensive coronary artery disease or has a closer association with infarction has not been determined.

METHODS

In 185 consecutive patients undergoing vascular surgery, we correlated ischemia duration, as detected on a continuous 12-lead ST-trend monitoring during the period 48 h to 72 h after surgery, with cardiac troponin-I (cTn-I) measured in the first three postoperative days and with postoperative cardiac outcome. Postoperative myocardial infarction was defined as cTn-I >3.1 ng/ml accompanied by either typical symptoms or new ischemic electrocardiogram (ECG) findings.

RESULTS

During 11,132 patient-hours of monitoring, 38 patients (20.5%) had 66 transient ischemic events, all but one denoted by ST-segment depression. Twelve patients (6.5%) sustained PMI; one of those patients died. All infarctions were non-Q-wave and were detected by a rise in cTn-I during or immediately after prolonged, ST depression-type ischemia. The average duration ofischemia in patients with PMI was 226+/-164 min (range: 29 to 625), compared with 38+/-26 min (p = 0.0000) in 26 patients with ischemia but not infarction. Peak cTn-I strongly correlated with the longest, as well as cumulative, ischemia duration (r = 0.83 and r = 0.78, respectively). Ischemic ECG changes were completely reversible in all but one patient who had persistent new T wave inversion. All ischemic events culminating in PMI were preceded by an increase in heart rate (delta heart rate = 32+/-15 beats/min), and most (67%) of them began at the end of surgery and emergence from anesthesia.

CONCLUSIONS

Prolonged, ST depression-type ischemia progresses to MI and is strongly associated with the majority of cardiac complications after vascular surgery.

Non-invasive detection of human cardiomyocyte death using methylation patterns of circulating DNA

Detection of cardiomyocyte death is crucial for the diagnosis and treatment of heart disease. Here we use comparative methylome analysis to identify genomic loci that are unmethylated specifically in cardiomyocytes, and develop these as biomarkers to quantify cardiomyocyte DNA in circulating cell-free DNA (cfDNA) derived from dying cells. Plasma of healthy individuals contains essentially no cardiomyocyte cfDNA, consistent with minimal cardiac turnover. Patients with acute ST-elevation myocardial infarction show a robust cardiac cfDNA signal that correlates with levels of troponin and creatine phosphokinase (CPK), including the expected elevation-decay dynamics following coronary angioplasty. Patients with sepsis have high cardiac cfDNA concentrations that strongly predict mortality, suggesting a major role of cardiomyocyte death in mortality from sepsis. A cfDNA biomarker for cardiomyocyte death may find utility in diagnosis and monitoring of cardiac pathologies and in the study of normal human cardiac physiology and development.

The detection of cardiomyocyte death is a critical aspect in the diagnosis and monitoring of heart diseases. Here the authors show that cardiomyocyte-specific methylation patterns of circulating cell-free DNA may serve as a biomarker of cardiac cell death in infarcted and septic patients.

Perioperative myocardial ischemia and infarction: identification by continuous 12-lead electrocardiogram with online ST-segment monitoring

BACKGROUND

Perioperative myocardial ischemia is conventionally monitored using five electrocardiographic leads, with only one precordial lead placed at V5. This is based on studies from more than a decade ago. The authors reassessed this convention by analyzing data obtained from continuous on-line 12-lead electrocardiographic monitoring.

METHODS

One hundred eighty-five consecutive patients undergoing vascular surgery were monitored by continuous 12-lead ST-trend analysis during and for 48-72 h after surgery. Cardiac troponin I was measured in the first 3 postoperative days, and cardiac outcome was prospectively recorded. Ischemia was defined as ST deviation, relative to the reference preanesthesia electrocardiogram, of 0.2 mV or more in one lead or 0.1 mV or more in two contiguous leads, lasting more than 10 min.

RESULTS

During 11,132 patient-hours of monitoring, 38 patients (20.5%) had 66 transient ischemic events, with all but one denoted by ST-segment depression. Twelve patients (6.5%) sustained postoperative infarction (cardiac troponin I > 3.1 ng/ml). Among the 38 patients with ischemia, lead V3 most frequently (86.8%) demonstrated ischemia, followed by V4 (78.9%) and V5 (65.8%). Among the 12 patients with infarction, V4 was most sensitive to ischemia (83.3%), followed by V3 and V5 (75% each). Combining two precordial leads increased the sensitivity for detecting ischemia (97.4% for V3 + V5 and 92.1% for either V4 + V5 or V3 + V4) and infarction (100% for V4 + V5 or V3 + V5 and 83.3% for V3 + V4). On average, baseline preanesthesia ST was above isoelectric in V1 through V3 and below isoelectric in V5 through V6. Lead V4 was closest to the isoelectric level on the baseline electrocardiogram, rendering it most suitable for ischemia monitoring.

CONCLUSIONS

As a single lead, V4 is more sensitive and appropriate than V5 for detecting prolonged postoperative ischemia and infarction. Two precordial leads or more are necessary so as to approach a sensitivity of greater than 95% for detection of perioperative ischemia and infarction.

Monitoring liver damage using hepatocyte-specific methylation markers in cell-free circulating DNA

Liver damage is typically inferred from serum measurements of cytoplasmic liver enzymes. DNA molecules released from dying hepatocytes are an alternative biomarker, unexplored so far, potentially allowing for quantitative assessment of liver cell death. Here we describe a method for detecting acute hepatocyte death, based on quantification of circulating, cell-free DNA (cfDNA) fragments carrying hepatocyte-specific methylation patterns. We identified 3 genomic loci that are unmethylated specifically in hepatocytes, and used bisulfite conversion, PCR, and massively parallel sequencing to quantify the concentration of hepatocyte-derived DNA in mixed samples. Healthy donors had, on average, 30 hepatocyte genomes/ml plasma, reflective of basal cell turnover in the liver. We identified elevations of hepatocyte cfDNA in patients shortly after liver transplantation, during acute rejection of an established liver transplant, and also in healthy individuals after partial hepatectomy. Furthermore, patients with sepsis had high levels of hepatocyte cfDNA, which correlated with levels of liver enzymes aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Duchenne muscular dystrophy patients, in which elevated AST and ALT derive from damaged muscle rather than liver, did not have elevated hepatocyte cfDNA. We conclude that measurements of hepatocyte-derived cfDNA can provide specific and sensitive information on hepatocyte death, for monitoring human liver dynamics, disease, and toxicity.

Cardiac Troponin After Major Vascular Surgery

OBJECTIVES

We sought to determine the role of preoperative predictors, particularly ischemia, on preoperative thallium scanning (PTS) and coronary revascularization on low-level and conventional troponin elevations after major vascular surgery.

BACKGROUND

Postoperative cardiac troponin (cTn) elevations have recently been shown to predict both short- and long-term mortality after vascular surgery.

METHODS

The perioperative data, including PTS and subsequent coronary revascularization, continuous perioperative 12-lead ST-segment trend monitoring, cTn-I and/or cTn-T, and creatine kinase-MB fraction in the first three postoperative days, were prospectively collected in 501 consecutive elective major vascular procedures.

RESULTS

Moderate to severe inducible ischemia on PTS was associated with a 49.0% incidence of low-level (cTn-I >0.6 and/or cTn-T >0.03 ng/ml) and 22.4% conventional (cTn-I >1.5 and/or cTn-T >0.1 ng/ml) troponin elevation. In contrast, patients with preoperative coronary revascularization had 23.4% and 6.4% low-level and conventional troponin elevations, respectively, similar to patients without ischemia on PTS. By multivariate logistic regression, ischemia on PTS was the most important predictor of both low-level and conventional troponin elevations (adjusted odds ratios [ORs] 2.5 and 2.7, p = 0.02 and 0.04, respectively), whereas preoperative coronary revascularization predicted less troponin elevations (adjusted ORs 0.35 and 0.16, p = 0.045 and 0.022, respectively). Postoperative ischemia (>10 min), the more so prolonged (>30 min) ischemia was the only independent predictor of troponin elevation if added with the preoperative predictors to the multivariate analysis (ORs 15.8 and 22.8, respectively, p < 0.001).

CONCLUSIONS

Troponin elevations occur frequently after vascular surgery. They are strongly associated with postoperative ischemia, predicted by inducible ischemia on PTS, and reduced by preoperative coronary revascularization.

Perioperative ischemia and cardiac complications in major vascular surgery: importance of the preoperative twelve-lead electrocardiogram

PURPOSE

To investigate the associations between specific preoperative 12-lead electrocardiogram (ECG) abnormalities, perioperative ischemia, and postoperative myocardial infarction or cardiac death in major vascular surgery.

METHODS

Two prospective studies on perioperative myocardial ischemia performed in two tertiary university hospitals were combined to include 405 patients. All preoperative ECGs were analyzed according to the Sokolow-Lyon criteria for left ventricular hypertrophy by investigators who were blinded to the patients' perioperative clinical course. Perioperative myocardial ischemia was detected by continuous ECG recording, and postoperative cardiac complications included myocardial infarction and cardiac death.

RESULTS

A total of 19 postoperative cardiac complications occurred (two cardiac deaths and 17 myocardial infarctions). Voltage criteria for left ventricular hypertrophy (78 patients, 19%) and ST segment depression greater than 0.5 mm (98 patients, 24.2%) on preoperative ECGs were both significantly associated with postoperative myocardial infarction or cardiac death (odds ratio, 4.2 and 4.7; p = 0.001 and 0.0005, respectively) and with longer intraoperative and postoperative myocardial ischemia. In each of the two study groups, a preoperative ECG abnormality that involved voltage criteria, ST segment depression, or both (134 patients, 33.1%) was more predictive of postoperative cardiac complications than any other preoperative clinical variable, including a history of myocardial infarction or angina pectoris, diabetes mellitus, pathologic Q-wave by ECG, or preoperative myocardial ischemia. The combined duration of intraoperative and postoperative ischemia and the preoperative ECG with either voltage criteria or ST segment depression were the only independent factors associated with adverse cardiac events by multivariate analysis (p < or = 0.0001 and p = 0.02, respectively).

CONCLUSION

Left ventricular hypertrophy and ST segment depression on preoperative 12-lead ECGs are important markers of increased risk for myocardial infarction or cardiac death after major vascular surgery.

Myocardial Dysfunction in Severe Sepsis and Septic Shock: No Correlation With Inflammatory Cytokines in Real-life Clinical Setting

BACKGROUND

In vitro studies suggested that circulating inflammatory cytokines cause septic myocardial dysfunction. However, no in vivo clinical study has investigated whether serum inflammatory cytokine concentrations correlate with septic myocardial dysfunction.

METHODS

Repeated echocardiograms and concurrent serum inflammatory cytokines (IL-1β, IL-6, IL-8, IL-10, IL-18, tumor necrosis factor-α, and monocyte chemoattractant protein-1) and cardiac biomarkers (high-sensitivity [hs] troponin-T and N-terminal pro-B-type natriuretic peptide [NT-proBNP]) were examined in 105 patients with severe sepsis and septic shock. Cytokines and biomarkers were tested for correlations with systolic and diastolic dysfunction, sepsis severity, and mortality.

RESULTS

Systolic dysfunction defined as reduced left ventricular ejection fraction (LVEF) < 50% or < 55% and diastolic dysfunction defined as e'-wave < 8 cm/s on tissue-Doppler imaging (TDI) or E/e'-ratio were found in 13 (12%), 24 (23%), 53 (50%), and 26 (25%) patients, respectively. Forty-four patients (42%) died in-hospital. All cytokines, except IL-1, correlated with Sequential Organ Failure Assessment and APACHE (Acute Physiology and Chronic Health Evaluation) II scores, and all cytokines predicted mortality. IL-10 and IL-18 independently predicted mortality among cytokines (OR = 3.1 and 28.3, P = .006 and < 0.0001). However, none of the cytokines correlated with LVEF, end-diastolic volume index (EDVI), stroke-volume index (SVI), or s'-wave and e'-wave velocities on TDI (Pearson linear and Spearman rank [ρ] nonlinear correlations). Similarly, no differences were found in cytokine concentrations between patients dichotomized to high vs low LVEF, EDVI, SVI, s'-wave, or e'-wave (Mann-Whitney U tests). In contrast, NT-proBNP strongly correlated with both reduced LVEF and reduced e'-wave velocity, and hs-troponin-T correlated mainly with reduced e'-wave.

CONCLUSIONS

Unlike cardiac biomarkers, none of the measured inflammatory cytokines correlates with systolic or diastolic myocardial dysfunction in severe sepsis or septic shock.

Preoperative thallium scanning, selective coronary revascularization, and long-term survival after major vascular surgery

BACKGROUND

Ischemia on thallium scanning is a strong predictor of long-term mortality in CAD patients. Whether coronary revascularization (CR) in patients with significant ischemia on preoperative thallium scanning (PTS) improves long-term survival after major vascular surgery has not been determined.

METHODS AND RESULTS

The perioperative data, including PTS and subsequent CR in patients with moderate to severe reversible ischemia on PTS, and long-term survival of 502 consecutive patients who underwent 578 major vascular procedures were analyzed retrospectively. Patients with PTS who ultimately did not undergo the planned vascular operation were also studied. Cox regression and propensity score analyses were used to analyze survival. A total of 407 patients (81.1%) had PTS: 221 (54.3%) had no or mild defects (group I); 50 (12.3%) had moderate-severe fixed defects (group II); 62 (15.2%) had moderate-severe reversible ischemia yet did not undergo CR (group III); and 74 (18.2%) had moderate-severe reversible ischemia and subsequent CR by CABG (36) or PTCA (38; group IV). Patients who sustained major complications as a result of the preoperative cardiac workup were included in group IV. By multivariate analysis, age, type of vascular surgery, presence of diabetes, previous myocardial infarction, and moderate-severe ischemia on PTS independently predicted mortality (P=0.001, 0.009, 0.039, 0.006, and 0.029, respectively), and preoperative CR predicted improved survival (OR 0.52, P=0.018). Group IV had better survival than group III even when subdivided according to normal and reduced left ventricular function (OR 0.40 and 0.41, P=0.035 and 0.021, respectively).

CONCLUSIONS

Long-term survival after major vascular surgery is significantly improved if patients with moderate-severe ischemia on PTS undergo selective CR.

Myocardial ischemia, cardiac troponin, and long-term survival of high-cardiac risk critically ill intensive care unit patients*

OBJECTIVES

To determine the incidence and association of myocardial ischemia with troponin elevation and survival in high-cardiac-risk intensive care patients.

DESIGN

Prospective observational study.

SETTING

Intensive care unit of a tertiary hospital.

SUBJECTS

One-hundred one general intensive care unit patients having a history of coronary artery disease or at least two risk factors for coronary artery disease.

INTERVENTIONS

Continuous 12-lead electrocardiographic monitoring with on-line ST-trend analysis, daily cardiac troponin measurements, clinical and physiologic assessment, and up to 2-yr follow-up for survival.

MEASUREMENTS AND MAIN RESULTS

During 8,988 hrs or a mean +/- sd of 95 +/- 85 hrs/patient of continuous 12-lead electrocardiographic monitoring, 21 patients (21%) had ischemic ST-segment changes, characterized in most (19) by ST depression and lasting >60 mins in 15 (71.4%). Of the 38 patients (38%) with troponin elevation, myocardial infarction was clinically suspected in four and myocardial ischemia on continuous 12-lead electrocardiographic monitoring was observed in 14 (36.8%). Fourteen (66.7%) of the patients with ischemic ST changes and 12 (75%) of those with prolonged (>60 mins) ischemia had troponin elevation. The sensitivity, specificity, and positive and negative predictive values of prolonged (>60 mins) ischemia predicting troponin elevation were 31.6%, 95.2%, 80.0%, and 69.8%, respectively. Prolonged (>60 mins) ischemia was significantly associated with troponin elevation by both univariate and multivariate analyses (odds ratio = 9.0; p = .008). Acute Physiology and Chronic Health Evaluation II score, renal failure, and the use of norepinephrine also independently predicted troponin elevation. Troponin but not ischemia predicted increased 1-month, 6-month, and 2-yr mortality (odds ratio = 6.0, 3.2, and 2.99, respectively; p < .001).

CONCLUSIONS

Silent ischemia is strongly associated with troponin elevation in high-cardiac-risk intensive care unit patients, and troponin elevation predicts both early and late mortality.

Myocardial infarction and cerebrovascular accident following non-cardiac surgery: differences in postoperative temporal distribution and risk factors

BACKGROUND

Myocardial infarction and stroke after non-cardiac surgery are two ominous cardiovascular complications believed to share similar pathophysiological processes. However, the differences in the temporal distribution between them have not been adequately investigated in a large cohort of patients.

METHODS AND RESULTS

The preoperative clinical features and daily occurrence of myocardial infarction and stroke were routinely recorded in 36 634 consecutive patients following elective non-cardiac, non-carotid surgery. The preoperative characteristics and postoperative daily distribution of postoperative myocardial infarction and stroke were compared using exponential and linear regressions models. Myocardial infarction and stroke occurred in 122 (0.33%) and 126 (0.34%) patients, respectively, during the first 30 days after surgery. More patients with myocardial infarction had diabetes mellitus and cardiac disease (P = 0.041 and <0.0001, respectively) whereas more patients with stroke were older and female (P = 0.003 and 0.038, respectively). The peak incidence of myocardial infarction was on the day of surgery (43%) and declined exponentially thereafter (F = 725.4, P < 0.0001). However, postoperative stroke best fitted a linear regression with almost even daily distribution (F = 15.9, P = 0.0004). The median time to myocardial infarction was one day [95% confidence interval (95% CI) = 0-2 days] compared with nine days (95% CI = 7-11 days) for stroke.

CONCLUSIONS

The peak incidence of postoperative myocardial infarction is early after non-cardiac surgery and declines exponentially thereafter, as opposed to stroke, which occurs at a constant rate during the postoperative period. Myocardial infarction and cerebrovascular accident following non-cardiac surgery differ in their preoperative risk factors, and in the postoperative time-line of their occurrence.

Perioperative myocardial ischemia in carotid endarterectomy under cervical plexus block and prophylactic nitroglycerin infusion

Perioperative myocardial ischemia was evaluated in 36 consecutive carotid endarterectomy procedures carried out on patients with a high (72.2%) prevalence of ischemic heart disease. The procedures were performed under cervical plexus block plus a prophylactic intravenous nitroglycerin infusion. Findings of myocardial ischemia on perioperative (48 hours) continuous electrocardiogram recordings were correlated with preoperative cardiac status, perioperative continuous intra-arterial blood pressure measurements, and postoperative cardiac outcome. In two patients, ST segment analysis was un-interpretable because of bundle-branch blocks. Altogether, 64 episodes of significant ST segment depression were detected in 18 (52.9%) of the remaining procedures. In 8 (23.5%) procedures, ST segment depressions occurred either during carotid artery clamping at the time of the largest rise in blood pressure or within 2 hours of declamping, when blood pressure tended to decline. There were four (11.7%) postoperative cardiac events: three myocardial infarctions (one Q wave and two non-Q wave) and one episode of unstable angina pectoris. All four patients with cardiac events had early signs of myocardial ischemia either at the time of cross-clamping, or soon after declamping of the carotid artery. All myocardial infarctions developed following prolonged (> 10 hours) myocardial ischemia, starting with the first 20 hours after surgery. Thus, ST segment depression occurring during clamping or soon after carotid declamping was associated with cardiac complications (sensitivity 100% and specificity 86.6%) and suggests the possible usefulness of on-line ST segment trend monitoring.

A clinical survival score predicts the likelihood to benefit from preoperative thallium scanning and coronary revascularization before major vascular surgery

AIMS

Guidelines advocate selective non-invasive testing before major non-cardiac surgery, yet data defining who may benefit from such tests is lacking. We aimed to find the predictors that define patients who are most likely to benefit from preoperative cardiac testing and coronary revascularization (CR).

METHODS AND RESULTS

In 624 consecutive major vascular surgery patients, the preoperative thallium scanning (PTS) results and subsequent CRs were correlated with long-term (3-15 years) survival. Of all patients, 510 (80.6%) had PTS, 154 (24.7%) had moderate-severe ischaemia on PTS, and 96 (15.4%) underwent CR. Seven predictors: age >or=65, diabetes, cerebrovascular disease, ischaemic heart disease, congestive heart failure, ST-depression on preoperative ECG, and renal insufficiency, independently determined long-term survival. A long-term survival score (LTSS) comprised of these predictors, divided all patients into low, intermediate, and high-risk groups (0-1, 2-3, >or=4 predictors, respectively) with a 5-year survival of 83 +/- 2%, 60 +/- 3%, and 34 +/- 6%, respectively. Compared with low-risk patients, intermediate and high-risk patients had worse survival [HR (CI) = 2.6 (2.0-3.4) and 5.9 (4.1-8.9), respectively, P < 0.001]. Yet, only the intermediate-risk group had better long-term survival following preoperative CR [HR = 0.48 (0.31-0.75), P = 0.001]. The low-risk groups' favourable survival and high-risk groups' poor survival were not significantly affected by CR.

CONCLUSION

Intermediate-risk patients (LTSS 2-3) are most likely to have a long-term survival benefit from PTS and CR.

Anesthesia for the elderly: selected topics

PURPOSE OF REVIEW

With the graying of the Western population, there is a continuous increase in the proportion of elderly patients undergoing surgical procedures. Geriatric anesthesia is emerging from a 'subspecialty' to the mainstream of today's anesthesia and perioperative care. Much has been written on anesthesia for the elderly, but this review will concentrate on selected topics related to elderly care that represent current unresolved and pertinent issues for the care of the elderly surgical patient.

RECENT FINDINGS

Postoperative cognitive dysfunction, cardiac diastolic dysfunction and prophylactic perioperative beta-blockade in the process of major noncardiac surgery are three main topics that have recently attracted great interest in clinical practice and research, and have therefore been chosen as the selected topics for this current review.

SUMMARY

Although age is a clear risk factor for postoperative cognitive dysfunction, the association of general anesthesia with cognitive dysfunction is less clear, as is the effect of anesthesia per se or surgery on long-term cognitive dysfunction. Cardiac diastolic dysfunction is a relatively new and evolving concept in anesthesia and perioperative medicine, yet clearly diastolic dysfunction even with a normal ejection fraction may have a significant effect on the perioperative outcome and management of elderly patients. Small, but powerful studies have shown significant outcome benefit with prophylactic perioperative beta-blockade in high-risk patients undergoing major noncardiac surgery. Data from other studies, however, are still conflicting and the final verdict awaits larger scale outcome studies.

Performance of department staff in the window between discovery of collapse to cardiac arrest team arrival

INTRODUCTION

Guideline-directed therapy during the first minutes of resuscitation may be life saving. This study assessed the performance of American Heart Association (AHA) guidelines by trained departmental staff in the period between discovery of collapse and emergency team arrival.

METHODS

Over a period of 24 months, departmental performance prior to the arrival of the emergency team (median 180 s) was assessed by debriefings conducted within 24h of each event in a 740-bed tertiary hospital with a dedicated certified resuscitation team. Outcome measures were failure to meet AHA treatment recommendations (primary) and return of spontaneous circulation (ROSC)/survival to hospital discharge (secondary).

RESULTS

Two hundred and forty four events were included (216 patients). Mean age was 69+/-17 years; 45% were women. The underlying causes of collapse were mainly cardiac (39%) or respiratory (32%). Residents conducted most of the resuscitations (69%) prior to the arrival of the emergency team. Basic diagnostic measures such as assessments of pulse and rhythm were not performed in 19 and 33% of events. Therapeutic measures such as positive pressure ventilation, chest compressions and defibrillation were not provided according to the guidelines in 17, 12 and 44% of the events. ROSC occurred in 62% of events; 54% of VF/VT, 30% of asystole, 22% of PEA and 76% of bradyarrhythmias/severe bradycardias. Survival to hospital discharge was 37% overall and 41% for patients found in VF/VT (n=33).

CONCLUSIONS

Trained departmental staff performed poorly in the moments between patient discovery and arrival of the emergency team. Since patient outcomes were comparable to those described in the literature, poor resuscitation performance may be commonplace in hospitals where ward personnel are expected to deliver advanced life support prior to arrival of the emergency team.

Step baroreflex response in awake patients undergoing carotid surgery: time- and frequency-domain analysis

Step baroreceptor stimulation can provide an insight into the baroreflex control mechanism, yet this has never been done in humans. During carotid surgery under regional anesthesia, a step increase in baroreceptor stimulation occurs at carotid declamping immediately after removal of the intra-arterial atheromatous plaque. In 10 patients, the R-R interval and systolic and diastolic blood pressures (BP) were continuously recorded, and signals obtained within the time window from 10 min before until 10 min after carotid declamping were analyzed. Mean +/- SD time signals, power spectra, and transfer and coherence functions before and after declamping were calculated. Immediately after carotid declamping, both heart rate (HR) and BP declined in an exponential-like manner lasting 10.3 +/- 5.9 min, and their power spectra increased in the entire frequency range. Transfer function magnitude and coherence functions between BP and HR increased predominantly in the midfrequency region (approximately 0.1 Hz), with no change in phase function. Thus, in carotid endarterectomy patients, step increase in baroreceptor gain elicits a prolonged decline in HR and BP. Frequency analyses support the notion that the baroreflex control mechanism generates the midfrequency HR and BP variability, although other frequency regions are also affected.