Redox-based thrombelastographic method to detect carboxyhemefibrinogen-mediated hypercoagulability

Carbon Monoxide Poisoning and Developing Ischemic Heart Disease: A Nationwide Population-Based Nested Case-Control Study

Although there are several case reports showing that carbon monoxide (CO) poisoning causes ischemic heart disease (IHD), no large-scale epidemiological studies have shown a significant association between the two. To investigate the association between CO poisoning and IHD, a nested case-control study of 28,113 patients who experienced CO poisoning and 28,113 controls matched by sex and age was performed using the nationwide health database of South Korea. Based on a conditional logistic regression, there was a significantly higher risk of IHD among the CO poisoning group than among the control group (adjusted hazard ratio [HR], 2.16; 95% confidence interval [CI], 1.87–2.49). The risk of IHD after CO poisoning was higher among the younger age group under 40 years (adjusted HR, 4.85; 95% CI, 3.20–7.35), and it was much greater among those with comorbidities (adjusted HR, 10.69; 95% CI, 2.41–47.51). The risk of IHD was the highest within the first two years after CO poisoning (adjusted HR, 11.12; 95% CI, 4.54–27.22). Even if more than six years had passed, the risk was still significantly higher than among the control group (adjusted HR, 1.55; 95% CI, 1.27–1.89). The analyses imply that CO poisoning is associated with an increased risk of IHD.

Carbon Monoxide Poisoning

Carbon monoxide is a colorless, odorless, highly toxic gas primarily produced through the incomplete combustion of organic material. Carbon monoxide binds to hemoglobin and other heme molecules, causing tissue hypoxia and oxidative stress. Symptoms of carbon monoxide poisoning can vary from a mild headache to critical illness, which can make diagnosis difficult. When there is concern for possible carbon monoxide poisoning, the diagnosis can be made via blood co-oximetry. The primary treatment for patients with carbon monoxide poisoning is supplemental oxygen, usually delivered via a nonrebreather mask. Hyperbaric oxygen can also be used, but the exact indications are controversial.

Risk factors for venous thromboembolism after carbon monoxide poisoning: A nationwide population-based study

Introduction:

The risk of venous thromboembolism increases after acute carbon monoxide poisoning. However, studies on the characteristics of patients who develop venous thromboembolism after carbon monoxide poisoning are rare. The aim of this study was to identify the risk factors for venous thromboembolism within 3 months after carbon monoxide poisoning.

Methods:

This is a population-based study that employed nationwide claims data from South Korea. Among the carbon monoxide poisoning patients (⩾18 years), the characteristics of the groups with and without venous thromboembolism (pulmonary embolism or deep vein thrombosis) were identified. All the significant variables in the univariable analysis were included in the multivariable logistic regression to determine the risk factors for venous thromboembolism occurrence.

Results:

Among the 24,232 carbon monoxide poisoning patients, 130 subjects developed venous thromboembolism within 90 days of their carbon monoxide poisoning diagnosis. The significant risk factors for venous thromboembolism in the multivariable analysis were age (adjusted odds ratio (aOR) = 1.01; 95% confidence interval (CI) = 1.003–1.03), intensive care unit admission (aOR = 3.80; 95% CI = 2.34–6.12), length of stay (aOR = 1.02; 95% CI = 1.0001–1.04), congestive heart failure (aOR = 2.17; 95% CI = 1.36–3.42), and cancer (aOR = 1.94; 95% CI = 1.10–3.22). The adjusted odds ratios for intensive care unit admission for patients with pulmonary embolism and deep vein thrombosis were 3.05 (95% CI = 1.61–5.61) and 5.60 (95% CI = 2.89–10.90), respectively.

Conclusion:

Patients with older age, intensive care unit admission, a longer length of stay, congestive heart failure, or cancer are at greater risk of developing venous thromboembolism after carbon monoxide poisoning. In particular, intensive care unit admission was the strongest risk factor for venous thromboembolism, pulmonary embolism, and deep vein thrombosis. Monitoring and administering prophylactic treatments to prevent venous thromboembolism would be helpful in high-risk in carbon monoxide poisoning patients.

The anticoagulant effect of Apis mellifera phospholipase A2 is inhibited by CORM-2 via a carbon monoxide-independent mechanism

Bee venom phospholipase A₂ (PLA₂) has potential for significant morbidity. Ruthenium (Ru)-based carbon monoxide releasing molecules (CORM) inhibit snake venoms that are anticoagulant and contain PLA₂. In addition to modulating heme-bearing proteins with carbon monoxide, these CORM generate reactive Ru species that form adducts with histamine residues resulting in changes in protein function. This study sought to identify anticoagulant properties of bee venom PLA₂ via catalysis of plasma phospholipids required for thrombin generation. Another goal was to determine if Ru-based CORM inhibit bee venom PLA₂ via carbon monoxide release or via potential binding of reactive Ru species to a key histidine residue in the catalytic site of the enzyme. Anticoagulant activity of bee venom PLA₂ was assessed via thrombelastography with normal plasma. Bee venom PLA₂ was then exposed to different CORM and a metheme forming agent and anticoagulant activity was reassessed. Using Ru, boron and manganese-based CORM and a metheme forming agent, it was demonstrated that it was unlikely that carbon monoxide interaction with a heme group attached to PLA₂ was responsible for inhibition of anticoagulant activity by Ru-based CORM. Exposure of PLA₂ to a Ru-based CORM in the presence of histidine-rich human albumin resulted in loss of inhibition of PLA₂. Ru-based CORM likely inhibit bee venom PLA₂ anticoagulant activity via formation of reactive Ru species that bind to histidine residues of the enzyme.

Risk of Venous Thromboembolism After Carbon Monoxide Poisoning: A Nationwide Population-Based Study

STUDY OBJECTIVE

Few studies have investigated the association between carbon monoxide (CO) poisoning and risk of venous thromboembolism. We aim to identify the risk of pulmonary embolism and deep venous thrombosis after CO poisoning.

METHODS

We conducted a nationwide cohort-crossover study using administrative claims data in Korea. We compared the risk of venous thromboembolism (pulmonary embolism or deep venous thrombosis) in the cohort period after CO poisoning to that of the same period 1 year later (crossover period), using conditional logistic regression analysis.

RESULTS

We included 22,699 patients with a diagnosis of CO poisoning during the study period between 2004 and 2015. The risk of venous thromboembolism was significantly elevated during days 0 to 90 after CO poisoning (odds ratio 3.96; 95% confidence interval 2.50 to 6.25). However, this risk was not significantly elevated during subsequent postexposure periods through 360 days. During days 0 to 30 after CO poisoning, the risks of pulmonary embolism (odds ratio 22.00; 95% confidence interval 5.33 to 90.75) and deep venous thrombosis (odds ratio 10.33; 95% confidence interval 3.16 to 33.80) were significantly elevated.

CONCLUSION

We found that the risk of venous thromboembolism persisted for up to 90 days after CO poisoning. The risk was increased 22-fold for pulmonary embolism and 10-fold for deep venous thrombosis, especially in the first month after CO poisoning. Patients should be monitored for venous thromboembolism risk after CO poisoning.

De Novo Assessment and Review of Pan-American Pit Viper Anticoagulant and Procoagulant Venom Activities via Kinetomic Analyses

Snakebite with hemotoxic venom continues to be a major source of morbidity and mortality worldwide. Our laboratory has characterized the coagulopathy that occurs in vitro in human plasma via specialized thrombelastographic methods to determine if venoms are predominantly anticoagulant or procoagulant in nature. Further, the exposure of venoms to carbon monoxide (CO) or O-phenylhydroxylamine (PHA) modulate putative heme groups attached to key enzymes has also provided mechanistic insight into the multiple different activities contained in one venom. The present investigation used these techniques to characterize fourteen different venoms obtained from snakes from North, Central, and South America. Further, we review and present previous thrombelastographic-based analyses of eighteen other species from the Americas. Venoms were found to be anticoagulant and procoagulant (thrombin-like activity, thrombin-generating activity). All prospectively assessed venom activities were determined to be heme-modulated except two, wherein both CO and its carrier molecule were found to inhibit activity, while PHA did not affect activity (Bothriechis schlegelii and Crotalus organus abyssus). When divided by continent, North and Central America contained venoms with mostly anticoagulant activities, several thrombin-like activities, with only two thrombin-generating activity containing venoms. In contrast, most venoms with thrombin-generating activity were located in South America, derived from Bothrops species. In conclusion, the kinetomic profiles of venoms obtained from thirty-two Pan-American Pit Viper species are presented. It is anticipated that this approach will be utilized to identify clinically relevant hemotoxic venom enzymatic activity and assess the efficacy of locally delivered CO or systemically administered antivenoms.

Effects of Heme Modulation on Ovophis and Trimeresurus Venom Activity in Human Plasma

Geographic isolation and other factors result in evolution-driven diversity of the enzymatic composition of venom of pit vipers in the same genus. The present investigation sought to characterize venoms obtained from such genetically diverse Ovophis and Trimeresurus pit vipers utilizing thrombelastographic coagulation kinetic analyses. The coagulation kinetics of human plasma were assessed after exposure to venom obtained from two Ovophis and three Trimeresurus species. The potency of each venom was defined (µg/mL required to equivalently change coagulation); additionally, venoms were exposed to carbon monoxide (CO) or a metheme-inducing agent to modulate any enzyme-associated heme. All venoms had fibrinogenolytic activity, with four being CO-inhibitable. While Ovophis venoms had similar potency, one demonstrated the presence of a thrombin-like activity, whereas the other demonstrated a thrombin-generating activity. There was a 10-fold difference in potency and 10-fold different vulnerability to CO inhibition between the Trimeresurus species. Metheme formation enhanced fibrinogenolytic-like activity in both Ovophis species venoms, whereas the three Trimeresurus species venoms had fibrinogenolytic-like activity enhanced, inhibited, or not changed. This novel “venom kinetomic” approach has potential to identify clinically relevant enzymatic activity and assess efficacy of antivenoms between genetically and geographically diverse species.

Role of heme modulation in inhibition of Atheris, Atractaspis, Causus, Cerastes, Echis, and Macrovipera hemotoxic venom activity

Venomous snake bite and subsequent coagulopathy is a significant source of morbidity and mortality worldwide. The gold standard to treat coagulopathy caused by these venoms is the administration of antivenom; however, despite this therapy, coagulopathy still occurs and recurs. Of interest, our laboratory has demonstrated in vitro and in vivo that coagulopathy-inducing venom exposed to carbon monoxide (CO) is inhibited, potentially by an attached heme. The present investigation sought to determine if venoms derived from snakes of the African genera Atheris, Atractaspis, Causus, Cerastes, Echis, and Macrovipera that have no or limited antivenoms available could be inhibited with CO or with the metheme-inducing agent, O-phenylhydroxylamine (PHA). Assessing changes in coagulation kinetics of human plasma with thrombelastography, venoms were exposed in isolation to CO or PHA. Eight species were found to have procoagulant activity consistent with the generation of human thrombin, while one was likely fibrinogenolytic. All venoms were significantly inhibited by CO/PHA with species-specific variation noted. These data demonstrate indirectly that the heme is likely bound to these disparate venoms as an intermediary modulatory molecule. In conclusion, future investigation is warranted to determine if heme could serve as a potential therapeutic target to be modulated during treatment of envenomation by hemotoxic enzymes.

CatroxMP-II: a heme-modulated fibrinogenolytic metalloproteinase isolated from Crotalus atrox venom

It has been recently demonstrated that the hemotoxic venom activity of several species of snakes can be inhibited by carbon monoxide (CO) or a metheme forming agent. These and other data suggest that the biometal, heme, may be attached to venom enzymes and may be modulated by CO. A novel fibrinogenolytic metalloproteinase, named CatroxMP-II, was isolated and purified from the venom of a Crotalus atrox viper, and subjected to proteolysis and mass spectroscopy. An ion similar to the predicted singly charged m/z of heme at 617.18 was identified. Lastly, CORM-2 (tricarbonyldichlororuthenium (II) dimer, a CO releasing molecule) inhibited the fibrinogenolytic effects of CatroxMP-II on coagulation kinetics in human plasma. In conclusion, we present the first example of a snake venom metalloproteinase that is heme-bound and CO-inhibited.

Carbon monoxide inhibits hemotoxic activity of Elapidae venoms: potential role of heme

Envenomation by hemotoxic enzymes continues to be a major cause of morbidity and mortality throughout the world. With regard to treatment, the gold standard to abrogate coagulopathy caused by these venoms is still the administration of antivenom; however, despite antivenom therapy, coagulopathy still occurs and recurs. Of interest, this laboratory has demonstrated in vitro and in vivo that coagulopathy inducing venom derived from snakes of the family Viperidae exposed to carbon monoxide (CO) is inhibited, potentially by an attached heme. The present investigation sought to determine if venoms derived from snakes of the Elapidae family (taipans and cobras) could also be inhibited with CO or with the metheme inducing agent, O-phenylhydroxylamine (PHA). Assessing changes in coagulation kinetics of human plasma with thrombelastography, venoms from Elapidae snakes were exposed in isolation to CO (five species) or PHA (one specie) and placed in human plasma to assess changes in procoagulant or anticoagulant activity. The procoagulant activity of two taipan venoms and anticoagulant activity of three cobra venoms were significantly inhibited by CO. The venom of the inland taipan was also inhibited by PHA. In sum, these data demonstrate indirectly that the biometal heme is likely bound to these disparate venoms as an intermediary modulatory molecule. In conclusion, CO may not just be a potential therapeutic agent to treat envenomation but also may be a potential modulator of heme as a protective mechanism for venomous snakes against injury from their own proteolytic venoms.

Direct Inhibitory Effects of Carbon Monoxide on Six Venoms Containing Fibrinogenolytic Metalloproteinases

Since the introduction of antivenom administration over a century ago to treat venomous snake bite, it has been the most effective therapy for saving life and limb. However, this treatment is not always effective and not without potential life-threatening side effects. We tested a new paradigm to abrogate the plasmatic anticoagulant effects of fibrinogenolytic snake venom metalloproteinases (SVMP) by inhibiting these Zn⁺² -dependent enzymes directly with carbon monoxide (CO) exposure. Assessment of the fibrinogenolytic effects of venoms collected from the Arizona black rattlesnake, Northern Pacific rattlesnake, Western cottonmouth, Eastern cottonmouth, Broad-banded copperhead and Southern copperhead on human plasmatic coagulation kinetics was performed with thrombelastography in vitro. Isolated exposure of all but one venom (Southern copperhead) to CO significantly decreased the ability of the venoms to compromise coagulation. These results demonstrated that direct inhibition of transition metal-containing venom enzymes by yet to be elucidated mechanisms (e.g. CO, binding to Zn⁺² or displacing Zn⁺² from the catalytic site, CO binding to histidine residues) can in many instances significantly decrease fibrinogenolytic activity. This new paradigm of CO-based inhibition of the anticoagulant effects of SVMP could potentially diminish haemostatic compromise in envenomed patients until antivenom can be administered.

Decreased snake venom metalloproteinase effects via inhibition of enzyme and modification of fibrinogen

Since the introduction of antivenom administration 120 years ago to treat venomous snake bit, it has been the gold standard for saving life and limb. However, this therapeutic approach is not always effective and not without potential life-threatening side effects. We tested a new paradigm to abrogate the plasmatic anticoagulant effects of fibrinogenolytic snake venom metalloproteinases by modification of fibrinogen with iron and carbon monoxide and by inhibiting these Zn(2+) dependent metalloproteinases directly with carbon monoxide exposure. Assessment of the fibrinogenolytic effects of venoms collected from Puff adder, Gaboon viper and Indian cobra snakes on plasmatic coagulation kinetics was performed with thrombelastography. Pretreatment of plasma with iron and carbon monoxide exposure markedly attenuated the effects of all three venoms, and direct pretreatment of each venom with carbon monoxide also significantly decreased the ability to compromise coagulation. These results demonstrated that the introduction of a transition metal (e.g., modulation of the α-chain of fibrinogen with iron), modulation of transition metal in heme (e.g., carbon monoxide modulation of fibrinogen-bound heme iron), and direct inhibition of transition metal containing venom enzymes (e.g., CO binding to Zn(2+) or displacing Zn(2+) from the catalytic site) significantly decreased fibrinogenolytic activity. This biometal modulation strategy to attenuate the anticoagulant effects of snake venom metalloproteinases could potentially diminish hemostatic injury in envenomed patients until antivenom can be administered.

Left Ventricular Assist Device-Associated Carbon Monoxide and Iron-Enhanced Hypercoagulation: Impact of Concurrent Disease

Left ventricular assist device (LVAD) therapy is associated with thrombophilia despite anticoagulation. Of interest, LVAD patients have increased carboxyhemoglobin, a measure of upregulated heme oxygenase (Hmox) activity that releases carbon monoxide (CO) and iron. Given that CO and iron enhance plasmatic coagulation, we determined if LVAD patients had hypercoagulability and decreased fibrinolytic vulnerability with measurable CO and iron-mediated effects. Blood samples were obtained a month or more after implantation of the LVAD. Thrombelastographic methods to assess coagulation kinetics, fibrinolytic kinetics, formation of carboxyhemefibrinogen, and iron-mediated enhancement of clot growth were utilized. Coagulation and fibrinolytic parameter normal individual (n = 30) plasma values were determined. Sixteen LVAD patients were studied. CO and iron enhancement of coagulation were observed in the majority of LVAD patients, contributing to hypercoagulation. However, most patients demonstrated abnormally increased rates of clot lysis. Critically, hemolysis as assessed by circulating lactate dehydrogenase activity was small in this cohort, and only four patients without comorbid states (e.g., obesity, diabetes, sleep apnea) were hypercoagulable with evidence of Hmox upregulation. However, seven patients with comorbidities were hypercoagulable with Hmox upregulation. Future investigation of CO and iron-related thrombophilia and comorbid disease is warranted to define its role in LVAD-related thrombosis.

Bariatric patients have plasmatic hypercoagulability and systemic upregulation of heme oxygenase activity

Morbid obesity is associated with significant thrombophilia. Of interest, adipocytes obtained from obese patients have increased heme oxygenase (Hmox) activity, the endogenous enzyme responsible for carbon monoxide (CO) production. Given that CO enhances plasmatic coagulation, we determined whether morbidly obese patients undergoing bariatric surgery had an increase in endogenous CO and plasmatic hypercoagulability. CO was determined by noninvasive pulse oximetry measurement of carboxyhemoglobin (COHb). A thrombelastographic method to assess plasma coagulation kinetics and formation of carboxyhemefibrinogen (COHF) was utilized. Nonsmoking bariatric patients (n = 20, BMI 47 ± 8 kg/m, mean ± SD) had abnormally increased COHb concentrations of 2.7 ± 1.9%, indicative of Hmox upregulation. When coagulation kinetics of these bariatric patients were compared with values obtained from normal individuals' (n = 30) plasma, 70% (95% confidence interval 45.7-88.1%) had abnormally great velocity of clot formation, abnormally large clot strength, and COHF formation. Future investigation of Hmox-derived CO in the pathogenesis of obesity-related thrombophilia is warranted.

[Myocardial stunning in carbon monoxide poisoning in a pregnant woman]

L'intoxication au monoxyde de carbone (CO) est la première cause de décès par intoxication en France. La littérature est ancienne et peu connue. Les signes les plus fréquents de l'intoxication sont la triade: Céphalées; asthénie, faiblesse musculaire surtout des membres inférieurs. Ses conséquences sont potentiellement graves pour le fœtus quand elle survient chez la femme enceinte, il est particulièrement exposé au risque d'hypoxie en raison de la forte affinité de son hémoglobine pour le CO qui traverse aisément le placenta. Les événements cardiovasculaires ne sont pas rares et peuvent être responsable d'une morbi-mortalité assez importante qui peuvent être d'apparition rapide ou secondaire mais régressent habituellement en quelques jours. Des SCA peuvent survenir lors d'une une intoxication au CO avec à l'extrême infarctus myocardique avec surélévation du segment ST. Il paraît légitime de proposer pour toutes les patientes: l’éloignement maternel de la source de CO; l'oxygénothérapie à 100% au masque facial par les services de secours et pendant le transfert; le traitement par oxygénothérapie hyperbare pour toutes les femmes enceintes, le plus rapidement possible et quelque soit l’âge gestationnel.

Hemodialysis patients have plasmatic hypercoagulability and decreased fibrinolytic vulnerability: role of carbon monoxide

Chronic hemodialysis is associated with significant thrombophilia. Of interest, hemodialysis patients have increased carboxyhemoglobin (COHb) and exhaled carbon monoxide (CO), signs of upregulated heme oxygenase (Hmox) activity. Given that CO enhances plasmatic coagulation, we determined whether patients requiring chronic hemodialysis had an increase in endogenous CO, plasmatic hypercoagulability and decreased fibrinolytic vulnerability. Carbon monoxide was determined by noninvasive pulse oximetry measurement of COHb. Blood samples were obtained just before hemodialysis. Thrombelastographic methods to assess plasma coagulation kinetics, fibrinolytic kinetics, and formation of carboxyhemefibrinogen (COHF) were used. Hemodialysis patients (n = 45) had abnormally increased COHb concentrations of 2.2 ± 1.9%, indicative of Hmox upregulation. Coagulation and fibrinolytic parameter normal values were determined with normal individual (n = 30) plasma. Thirty-seven patients of the hemodialysis cohort had COHF formation (82.2%, [67.9%-92.0%]; mean, [95% confidence interval]), and many of this group of patients had abnormally great velocity of clot growth (73.3%, [58.1%-85.4%]) and strength (75.6%, [60.5%-87.1%]). Furthermore, over half of COHF positive patients had a hypofibrinolytic state, evidenced by an abnormally prolonged time to maximum rate of lysis (53.3%, [37.9%-68.6%]) and clot lysis time (64.4%, [48.8%-78.1%]). Carbon monoxide enhanced coagulation and diminished fibrinolytic vulnerability in hemodialysis patients. Future investigation of hemodialysis, CO-related thrombophilia is warranted.

Colon and pancreas tumors enhance coagulation: role of hemeoxygenase-1

Colon and pancreatic cancer are associated with significant thrombophilia. Colon and pancreas tumor cells have an increase in hemeoxygenase-1 (HO-1) activity, the endogenous enzyme responsible for carbon monoxide production. Given that carbon monoxide enhances plasmatic coagulation, we determined if patients undergoing resection of colon and pancreatic tumors had an increase in endogenous carbon monoxide and plasmatic hypercoagulability. Patients with colon (n = 17) and pancreatic (n = 10) tumors were studied. Carbon monoxide was determined by the measurement of carboxyhemoglobin (COHb). A thrombelastographic method to assess plasma coagulation kinetics and formation of carboxyhemefibrinogen (COHF) was utilized. Nonsmoking patients with colon and pancreatic tumors had abnormally increased COHb concentrations of 1.4 ± 0.9 and 1.9 ± 0.7%, respectively, indicative of HO-1 upregulation. Coagulation analyses comparing both tumor groups demonstrated no significant differences in any parameter; thus the data were combined for the tumor groups for comparison with 95% confidence interval values obtained from normal individuals (n = 30) plasma. Seventy percent of tumor patients had a velocity of clot formation greater than the 95% confidence interval value of normal individuals, with 53% of this hypercoagulable group also having COHF formation. Further, 67% of tumor patients had clot strength that exceeded the normal 95% confidence interval value, and 56% of this subgroup had COHF formation. Finally, 63% of all tumor patients had COHF formation. Future investigation of HO-1-derived carbon monoxide in the pathogenesis of colon and pancreatic tumor-related thrombophilia is warranted.

Iron and carbon monoxide enhance coagulation and attenuate fibrinolysis by different mechanisms

Two parallel lines of investigation elucidating novel mechanisms by which iron (scanning electron microscopy-based) and carbon monoxide (viscoelastic-based) enhance coagulation and diminish fibrinolysis have emerged over the past few years. However, a multimodal approach to ascertain the effects of iron and carbon monoxide remained to be performed. Such investigation could be important, as iron and carbon monoxide are two of the products of heme catabolism via heme oxygenase-1, an enzyme upregulated in a variety of disease states associated with thrombophilia. Human plasma was exposed to ferric chloride, carbon monoxide derived from carbon monoxide-releasing molecule-2, or their combination. Viscoelastic studies demonstrated ferric chloride and carbon monoxide mediated enhancement of velocity of growth, and final clot strength, with the combination of the two molecules noted to have all the prothrombotic kinetic effects of either separately. Parallel ultrastructural studies demonstrated separate types of fibrin polymer cross-linking and matting in plasma exposed to ferric chloride and carbon monoxide, with the combination sharing features of each molecule. In conclusion, we present the first evidence that iron and carbon monoxide interact with key coagulation and fibrinolytic processes, resulting in thrombi that begin to form more quickly, grow faster, become stronger, and are more resistant to lysis.

Thrombolytic therapy in a patient with inferolateral myocardial infarction after carbon monoxide poisoning

INTRODUCTION

ST segment elevation myocardial infarction (STEMI) due to coronary artery occlusion caused by intracoronary thrombosis in the setting of acute carbon monoxide (CO) poisoning is a very rare presentation. We present a case of intracoronary large and mobile thrombus formation after CO poisoning.

CASE PRESENTATION

A previously healthy 50-year-old woman was referred for CO poisoning. She had chest pain after exposure to CO. Her initial mental status was preoccupied with chest pain. Her initial CO fraction was 28.1%, and initial laboratory data showed creatine kinase-myocardial isoenzyme of 134 U/L (upper limit 25 U/L) and troponin I of >50 ng/mL (upper limit 0.06 ng/mL). Electrocardiography was carried out on admission, revealing an ST segment elevation in the inferolateral leads. After initial evaluation, coronary angiography was performed and an intracoronary large mobile thrombus was seen in the proximal left anterior descending (LAD) artery with no significant stenosis. We administered tenecteplase with heparin. After the thrombolytic therapy, ST elevation in the inferolateral leads resolved. Repeat angiography was performed after 24 h; the thrombus in LAD had resolved. The patient was discharged after 5 days, with persistent Q wave in the inferior leads and mild hypokinesia of the inferoposterior wall suggesting myocardial injury.

CONCLUSION

We describe intracoronary thrombus formation induced by CO poisoning. Because intracoronary thrombus can result in myocardial infarction, its consideration following CO poisoning is important. Patients with CO poisoning who have symptoms of STEMI should be carefully evaluated with serial electrocardiograms, cardiac biomarkers, and an echocardiogram. When there is evidence of acute myocardial injury, a primer in coronary angiography can determine which patients could benefit from intervention.

[Acute coronary syndrome with impaired left ventricular function in a carbon monoxide poisoning]

Carbon monoxide poisoning is the leading cause of death by poisoning in France. Neuropsychological symptoms are most common. We report on a patient with acute coronary syndrome and transient left ventricular dysfunction in carbon monoxide poisoning. Patient improved under hyperbaric oxygen therapy. Coronary angiography shows no significant lesion leading to myocardial stunning diagnose. Patients exposed to carbon monoxide must have systematic cardiac evaluation with electrocardiogram and dosage of biomarkers.

Brain tumors enhance plasmatic coagulation: the role of hemeoxygenase-1

BACKGROUND

Patients with brain tumors suffer significant thrombotic morbidity and mortality. In addition to increased thrombin generation via tumor release of tissue factor-bearing microparticles and hyperfibrinogenemia, brain tumors and surrounding normal brain likely generate endogenous carbon monoxide (CO) via the hemeoxygenase-1 (HO-1) system. CO has been shown to enhance plasmatic coagulation via formation of carboxyhemefibrinogen (COHF). Thus, our goals in this study were to determine whether patients with brain tumors had increased HO-1 upregulation/CO production, plasmatic hypercoagulability, and formation of COHF.

METHODS

Patients with brain tumors (N = 20) undergoing craniotomy had blood collected for determination of carboxyhemoglobin as a marker of HO-1 activity, plasmatic hypercoagulability (defined as clot strength > 95% confidence interval value of normal subject plasma), and COHF formation (determined with a thrombelastograph-based assay). Plasma obtained from commercially available normal subjects (N = 30) was used for comparison with brain tumor patient samples.

RESULTS

Brain tumor patients had carboxyhemoglobin concentrations of 1.5% ± 0.5% (mean ± SD), indicative of HO-1 upregulation. Compared with normal subject plasma, brain tumor patient plasma had significantly (P < 0.0001) greater clot formation velocity (5.2 ± 1.5 vs 9.5 ± 2.3 dynes/cm/s, respectively) and significantly (P = 0.00016) stronger final clot strength (166 ± 28 vs 230 ± 78 dynes/cm, respectively). Ten of the brain tumor patients had plasma clot strength that exceeded the 95% confidence interval value observed in normal subjects, and 12 of the brain tumor patients had COHF formation. Five of the brain tumor patients in the hypercoagulable subgroup had COHF formation. Last, 5 of the hypercoagulable patients had primary brain tumors, whereas the other 5 patients had metastatic tumors or an inflammatory mass lesion.

CONCLUSIONS

A subset of patients with brain tumors has increased endogenous CO production, plasmatic hypercoagulability, and COHF formation. Future investigation of the role played by HO-1 derived CO in the pathogenesis of brain tumor-associated thrombophilia is warranted.

Carbon monoxide: Anticoagulant or procoagulant?

Within the past decade there have been several investigations attempting to define the impact of exogenous and endogenous carbon monoxide exposure on hemostasis. Critically, two bodies of literature have emerged, with carbon monoxide mediated platelet inhibition cited as a cause of in vitro human and in vitro/in vivo rodent anticoagulation. In contrast, interaction with heme groups associated with fibrinogen, α₂-antiplasmin and plasmin by carbon monoxide has resulted in enhanced coagulation and decreased fibrinolysis in vitro in human and other species, and in vivo in rabbits. Of interest, the ultrastructure of platelet rich plasma thrombi demonstrates an abnormal increase in fine fiber formation and matting that are obtained from humans exposed to carbon monoxide. Further, thrombi obtained from humans and rabbits have very similar ultrastructures, whereas mice and rats have more fine fibers and matting present. In sum, there may be species specific differences with regard to hemostatic response to carbon monoxide. Carbon monoxide may be a Janus-faced molecule, with potential to attenuate or exacerbate thrombophilic disease.

Primary angioplasty in patient with ST-segment elevation myocardial infarction in the setting of intentional carbon monoxide poisoning

BACKGROUND

ST-segment elevation myocardial infarction (STEMI) due to coronary artery occlusion in the setting of acute carbon monoxide (CO) poisoning is a very rare presentation.

OBJECTIVE

Our aim was to report on the use of primary angioplasty in a patient with STEMI in the setting of CO poisoning.

CASE REPORT

A 36-year-old man with retrosternal chest pain was admitted after exposure to CO. The initial electrocardiogram (ECG) showed ST depression in I, aVL, and V3-V4 with slight ST elevation in II, III, aVF leads. Toxic carboxyhemoglobin level of 22% and troponin I of 2.19 μg/L were confirmed. After oxygen therapy the chest pain diminished, but after about 15 h it returned. The repeat ECG revealed normalization of previous ST depression with persistent ST elevation in II, III, aVF leads. The troponin I concentration was 5.94 μg/L. An echocardiogram demonstrated an apex hypokinesia involving the adjacent segments of the anterior and lateral wall. On the coronary angiogram, an acute occlusion of the distal left anterior descending coronary artery was confirmed. Primary percutaneous coronary intervention (PCI) of the infarct-related artery was performed. After PCI, the patient was symptom free and had partial ST-segment elevation resolution. The patient was discharged home after 7 days, with persistent ST-T changes and mild hypokinesia of the apex suggesting myocardial injury.

CONCLUSIONS

Patients with toxic CO exposure who have symptoms of STEMI should be carefully evaluated with serial ECG, cardiac necrosis marker measurements, and an echocardiogram. When there is evidence of myocardial injury, a wider use of coronary angiography can identify patients who could benefit from PCI.

C-reactive protein and fibrin clot strength measured by thrombelastography after coronary stenting

Inflammation is implicated in the progression of coronary artery disease and the molecular processes of inflammation and thrombosis are closely intertwined. Elevated levels of C-reactive protein (CRP) have been associated with an elevated risk of adverse ischaemic events after coronary stenting and hypercoagulability. Heightened whole blood clot strength measured by thrombelastography (TEG) has been associated with adverse ischaemic events after stenting. We intended to examine the relationship of CRP to plasma fibrin clot strength in patients after coronary stenting. Plasma fibrin clot strength was measured by TEG in 54 patients 16-24 h after undergoing elective percutaneous coronary intervention (PCI). Coagulation was induced in citrated plasma by addition of kaolin and CaCl2. Plasma levels of CRP and fibrinogen were measured by enzyme-linked immunoassay. Increasing quartiles of CRP were associated with increasing levels of maximal plasma fibrin clot strength measured by TEG (P < 0.001) and increasing BMI (P = 0.04). Patients in the highest quartile of CRP had significantly higher maximal fibrin clot strength (G) than the patients in the lowest quartile (G: 3438 ± 623 vs. 2184 ± 576 dyn/cm, P < 0.0001). Fibrinogen concentration was not significantly different across quartiles of CRP (P = 0.97). Patients with established coronary artery disease undergoing coronary stenting who have elevated CRP after PCI exhibit heightened maximal plasma fibrin clot strength as compared with those with low CRP. Thrombotic risk associated with elevated CRP may be linked to procoagulant changes and high tensile fibrin clot strength independent of fibrinogen concentration.

Plasma and whole blood clot strength measured by thrombelastography in patients treated with clopidogrel during acute coronary syndromes

INTRODUCTION

Treatment with clopidogrel, a selective platelet P2Y12 receptor antagonist, reduces risk of recurrent ischemic events in patients with acute coronary syndrome (ACS), by limiting platelet aggregation and activation. Stable whole blood clot formation requires activation of platelets, generation of fibrin and final fibrin crosslinks. In this study we intended to compare plasma and whole blood thrombelastography (TEG) measurements in patients during ACS.

MATERIALS AND METHODS

Whole blood and plasma samples from 32 patients with non-ST segment elevation myocardial infarction (NSTEMI) were collected after administration of clopidogrel. Whole blood and plasma fibrin clot strength (MA) were determined by TEG. Platelet aggregation was determined by light transmittance aggregometry (LTA) using adenosine 5'-diphosphate (ADP), thrombin receptor activation peptide (TRAP), or collagen as agonists. Fibrinogen and C-reactive protein (CRP) concentrations were measured by ELISA.

RESULTS

Heightened plasma fibrin clot strength was associated with increased platelet reactivity stimulated by ADP (ρ=0.536; p=0.002), TRAP (ρ=0.481; p=0.007), and collagen (ρ=0.538; p=0.01). In contrast to plasma fibrin MA, whole blood MA did not correlate with platelet aggregation. Platelet count was the primary contributor to the difference in thrombin induced whole blood MA and plasma fibrin MA. Increasing levels of CRP were associated with increased plasma fibrin clot strength and platelet reactivity.

CONCLUSIONS

Our data suggest that inflammation is associated with increased plasma fibrin clot strength and lower platelet inhibition by clopidogrel during ACS. Platelet count is a main contributor to additional contractile force of whole blood TEG as compared to plasma TEG during treatment with clopidogrel.