Activated Clotting Time Research Articles

CORRELATION BETWEEN POINT OF CARE ACTIVATED CLOTTING TIMES AND LABORATORY-DETERMINED ANTI-XA UNFRACTIONATED HEPARIN LEVELS TO GUIDE MANAGEMENT OF SHEATH REMOVAL

Femoral arterial access for coronary angiography is infrequent but still in use. Point-of-care (POC) activated clotting time (ACTs) analyzers to guide the timing of femoral sheath removal require increasingly disproportionate use of resources in ongoing maintenance and quality assurance for a low volume test. It is hypothesized that there is a strong correlation between POC ACTs and laboratory-determined anti-Xa unfractionated heparin (UFH) levels.

Excessive Unfractionated Heparin Dosing During Hemodialysis Explained by Access and Discordance Between Activated Clotting Time and Activated Partial Thromboplastin Time

Excessive Unfractionated Heparin Dosing During Hemodialysis Explained by Access and Discordance Between Activated Clotting Time and Activated Partial Thromboplastin Time

COVID-19 Infection Complicated by a Complete Occlusion of the Left Circumflex Artery With Acute Restenosis After Drug-Eluting Stent Placement

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause a hypercoagulable state that can complicate the management of patients presenting with acute myocardial infarction (MI). We present the case of a patient with coronavirus disease 2019 (COVID-19) with ST elevation MI who was treated with percutaneous coronary intervention and stenting to the left circumflex artery. He was treated appropriately with anticoagulation with appropriate activated clotting time. However, the coronary angiogram course was complicated with heavy thrombosis that involved the left circumflex artery and the left anterior descending artery. Physicians are urged to suspect heparin resistance in COVID-19 patients, particularly if those patients have venous thromboembolism or acute coronary syndrome while taking heparin.

Performance Assessment of a Multifaceted Unfractionated Heparin Dosing Protocol in Adult Patients on Extracorporeal Membrane Oxygenator.

The use of extracorporeal membrane oxygenator (ECMO) support devices are associated with complications, including bleeding and thrombosis. Unfractionated heparin (UFH) is the gold standard anticoagulant in ECMO patients. Clinically, UFH is monitored through activated clotting time (ACT), activated partial thromboplastin time (aPTT), and anti-factor Xa assay. It is unknown which assay best predicts anticoagulation effects in adults. To assess the correlation of UFH dosing and monitoring using an established protocol. A pilot, prospective cohort, historically controlled study was conducted at a tertiary care hospital. Patients ≥18 years-old who received ECMO on the multifaceted anticoagulation protocol were included and compared with those on the conventional method of anticoagulation. The primary end point was to assess the correlation between UFH dose and different monitoring methods throughout 72 hours using the new protocol guided by ACT and anti-factor Xa assay. In each arm, 20 patients were enrolled. The study revealed that anti-factor Xa assay had the largest number of "strong" correlations 11/20 (55%), followed by both aPTT and aPTT ratio 10/20 (50%), and, finally, ACT 2/20 (10%). Concordance between anti-factor Xa assay and the other monitoring parameters in the prospective arm was generally low: 31% with aPTT ratio, 26% with ACT, and 23% with aPTT. The adaption of a multifaceted anticoagulation protocol using anti-factor Xa assay may provide a better prediction of heparin dosing in adults ECMO patients compared with the conventional ACT-based protocol. Further studies are needed to assess the safety and different monitoring modalities.

Uninterrupted use of direct oral anticoagulants versus vitamin K antagonists for catheter ablation of atrial fibrillation with PVAC gold: incidence of silent cerebral microembolic events.

Silent cerebral microembolic events (SCE) after duty-cycled ablation of atrial fibrillation using PVAC have been detected by cerebral magnet resonance imaging (MRI) in a substantial number of patients. The purpose of this study was to investigate if uninterrupted oral anticoagulation with non-vitamin K antagonists (NOACs) compared with vitamin K antagonists (VKA) affects the incidence of SCE after pulmonary vein isolation (PVI) using PVAC Gold. Eighty-four consecutive patients (62 ± 15 years, 58% male) undergoing a first PVI were prospectively enrolled. Of these, 42 were on VKA and 42 on uninterrupted NOAC treatment. An activated clotting time (ACT) ≥ 350 s was targeted for ablation. Cerebral MRI the day after PVI revealed acute diffusion-weighted positive lesions in 11/42 (26%) VKA compared with 14/42 (33%) in NOAC patients (p = 0.634). No differences were found for lesion size, number of lesions/patient, and number of lesions indicating cerebral infarction (2.4% for VKA and 4.8% for NOAC patients). Seventy-five percent of NOAC patients with sporadic ACT levels < 300 s during PVI developed SCE compared with 22% of corresponding VKA patients (p = 0.030). VKA and NOAC subgroups with ACT ≥ 350 s had no reduced incidence of SCE compared with ACT 300-350 s. A significant, but comparable, number of patients under uninterrupted anticoagulation with VKA or NOACs still experience SCE after PVAC Gold PVI. NOAC patients with sporadic subtherapeutic ACT levels during PVI are at the highest risk for SCE while permanent ACT levels ≥ 350 s did not further reduce the incidence of SCE in both groups.

Global cerebral infarction after aortic arch replacement surgery in a patient with postoperatively revealed factor XII deficiency: a case report

BackgroundThis case report presents a case of a patient with global cerebral infarction of uncertain etiology following an emergency surgery for acute type A aortic dissection. As a result, factor XII deficiency was revealed postoperatively. To date, there have been several reports of cardiovascular surgery in patients with factor XII deficiency. However, all previous reports were of patients whose factor XII deficiency had been detected preoperatively; therefore, before this, there had been no reports of complications associated with factor XII deficiency following cardiovascular surgery.Case presentationWe report a case of emergency aortic arch replacement surgery for acute type A aortic dissection in a 57-year-old Japanese man. A blood test prior to the surgery showed coagulopathy, a platelet count of 117 × 109/L, a prothrombin time–international normalized ratio of 1.78, an activated partial thromboplastin time of 69.7 seconds, and fibrinogen < 50 mg/dl. A smaller-than-usual dose of heparin (8000 IU) was administered because the patient’s activated clotting time was extremely prolonged (> 999 seconds). After the heparin administration, the activated clotting time, measured every 30–60 minutes, remained unchanged (> 999 seconds); therefore, additional heparin was not administered during the surgery, and there was no clinical problem during cardiopulmonary bypass. However, a diagnosis of global cerebral infarction was made on the first postoperative day. An additional blood coagulation test performed on postoperative day 9 revealed factor XII deficiency (8.0%). Regarding the reason that global cerebral infarction occurred in the present case, two reasons were considered: One was factor XII deficiency itself, and the other was low-dose heparin administration during the cardiopulmonary bypass due to excessively prolonged activated clotting time caused by factor XII deficiency.ConclusionsFactor XII deficiency should be considered in patients with prolonged activated clotting time and spontaneous thrombosis in vascular surgeries. Moreover, the present case emphasizes that management of heparin during cardiopulmonary bypass should not be performed on the basis of activated clotting time monitoring alone, especially in a case with prolonged activated clotting time.

Factors associated with errors in the heparin dose response test: recommendations to improve individualized heparin management in cardiopulmonary bypass.

A critical aspect of cardiopulmonary bypass (CPB) is to achieve full anticoagulation to prevent thrombosis and consumptive coagulation without using excessive amount of heparin. This can be achieved with heparin dose response (HDR) test in vitro to calculate an individualized heparin bolus to reach a target activated clotting time (ACT) and heparin concentration. However, we often observe that the measured ACT (mACT) with the calculated heparin bolus gives significant errors, both positive (mACT is higher than expected) and negative (mACT is lower), from expected ACT (eACT). We performed a retrospective study of 250 patients who underwent cardiac surgery to attain an error distribution of the mACT from eACT with calculated heparin bolus. In addition, it is aimed to identify possible patterns of baseline ACT (bACT), calculated heparin concentration (CHC) and HDR slope that are associated with the significant positive and negative errors. We found that individualized heparin bolus by HDR test is consistently underestimated while it gave a significant number of positive and negative errors. Further analysis indicates that significant negative errors correlate with high bACT and slope and low CHC while significant positive errors with low bACT and slope and high CHC. The mACT can be substantially different from eACT. The accuracy of the HDR test appears to be dependent upon bACT, slope, and CHC. Based on our analysis, we provide several recommendations and a flow chart to improve the quality of individualized heparin management on CPB.

ECMO/CRRT combined support in the treatment of critically ill patients with novel coronavirus pneumonia.

We present the cases of two patients critically ill diagnosed with novel coronavirus pneumonia (NCP). Both patients were male and met the COVID-19 diagnostic criteria in the Guidelines For the Diagnosis and Treatment of COVID-19 issued by China’s National Health Commission. The diagnosis of COVID-19 was confirmed by a positive real-time fluorescent reverse transcription–polymerase chain raction (RT–PCR) test for 2019-nCoV nucleic acid. Patients were enrolled in the study if they were in a clinically critical condition on admission and had any of the following conditions: respiratory failure requiring mechanical ventilation, shock, or failure of other organs requiring intensive care unit (ICU) care and treatment. The indication for extracorporeal membrane oxygenation (ECMO) in critically ill patients with NCP at our treatment centre was severe acute respiratory distress syndrome (ARDS) with ineffective protective pulmonary ventilation. In our procedure, ECMO and continuous renal replacement therapy (CRRT) are combined; the right femoral vein and left femoral artery are selected for V-A ECMO, and the right internal jugular vein and femoral vein are selected for V-V ECMO. ECMO assistance A MAQUET extracorporeal heart–lung machine and a heparin-coated ECMO circuit were used for bothl patients. The cannula was placed in the femoral vein and artery under direct vision. Sheaths of appropriate specifications (14F–24F for the artery and 16F–26F for the vein) were selected according to intraoperative investigation. Heparin was used to maintain an activated coagulation time (ACT) of between 180 and 220 s, and ventilator parameters and oxygen concentrations were appropriately adjusted according to the results of artery and vein blood gas analysis. Intubation and the establishment, operation, daily management, and withdrawal of ECMO/CRRT were performed by the ECMO/CRRT multidisciplinary team (MDT).

A comparative analysis of four activated clotting time measurement devices in cardiac surgery with cardiopulmonary bypass

In cardiac surgery on cardiopulmonary bypass (CPB), heparin anticoagulation is monitored by point-of-care measurement of activated clotting time (ACT). The objective of this study was to compare four ACT systems in cardiac surgery in terms of their reproducibility, agreement and potential clinical impact at relevant medical decision points. The study included 40 cardiac surgery patients. Samples were taken at five time points before (T1), after heparinization for CPB (T2, T3, T4), and after heparin reversal (T5). The reproducibility, correlation, and differences in ACT values were assessed with two devices from each of the four ACT systems: Instrumentation Laboratory Hemochron Elite (Hmch), Medtronic HMS Plus (HMS), Abbott i-STAT, and Helena Abrazo. Subrange analyses were performed for low ACT values (results from T1, T5) and high ACT values (results from T2, T3, T4). Within-system analysis showed strong linear correlation between paired measurements (R = 0.968-0.993). However, Hmch showed poorer reproducibility with highest proportion of values that exceed a difference of 10% and highest overall standard error of 74 seconds across the measurement range compared to that of the others (range 39-47 seconds, respectively). For inter-system comparison, using Hmch as reference, ACTs were strongly correlated as follows: HMS (R = 0.938), i-STAT (R = 0.911), and Abrazo (R = 0.911). Agreement analysis in the high ACT range showed HMS tended to have higher ACT values with +11% bias over Hmch, whereas i-STAT (-8% bias) and Abrazo (-13% bias) tended to underestimate. Post-protamine ACT results were dependent on device type where Hmch yielded highest post-protamine ACT (+13% higher than baseline) compared to -16% for HMS, -10% for iSTAT and 0% for Abrazo. Each device had individual reproducibility and biases, which may impact peri-operative heparin management. Careful validation must be undertaken when adopting a different method as decision limits would be affected. Clinicians should also be cautious using ACT as the only indicator for full heparin reversal.

Can We Rely on the Activated Clotting Time to Measure Heparin Anticoagulation? A Clinical Evaluation of Two ACT Monitors.

The sensitivity to heparin during cardiopulmonary bypass (CPB) is determined by patient-specific characteristics and is assessed by the whole blood activated clotting time (ACT). We aimed to examine reliability measures between two different ACT monitors using Bland-Altman analysis: bias should not exceed 50 ± 50 seconds for measurements performed during CPB or 10 ± 10 seconds before and after CPB. The ACT response should be linear in relation to the concentration of heparin in plasma. Twenty patients (n = 20) aged 20-80 years and admitted for coronary artery bypass surgery were enrolled to this clinical observational study. ACT values and antifactor Xa were sampled: 1) before induction of anesthesia, 2) after heparin bolus, 3) during CPB at the start of rewarming, 4) at weaning from CPB, and 5) after heparin reversal. The evaluation comprised the Hemostasis Management System Plus™ (HMS, Medtronic Inc., Minneapolis, MN) and i-STAT™ (Abbott, Point of Care Inc., Princeton, NJ). Bias for the HMS Plus™ vs. i-STAT™ was +105 ± 119 seconds for measurements during CPB and +2.8 ± 11.7 seconds before and after CPB. Associated limits of agreement for the observed bias were ±235 and ±23 seconds, respectively. Inter-device correlation of ACT values was .46 (p < .001) during CPB; otherwise .48 (p = .02). Both devices produced ACT values unrelated (<10%) to the measured heparin concentration. The use of multivariable regression analysis demonstrated an independent association between the ACT measurement and hematocrit, however, not with the plasma concentration of heparin. ACT monitors demonstrate unacceptable bias differences, combined with wide limits of agreement. The ACT response correlated with hematocrit, but not with the actual heparin concentration.

The effect of tranexamic acid on the values of activated clotting time in patients undergoing cardiac surgery: A PRISMA-compliant systematic review and meta-analysis

Study objectiveActivated clotting time (ACT) is a non-specific test to evaluate the adequacy of systemic heparinization whose value could be influenced by many factors. Tranexamic acid (TXA) is a widely used antifibrinolytic agent worldwide and whether TXA influences ACT value in cardiac surgical patients remains unknown. Current study was performed to address this question. DesignSystematic review and meta-analysis. PUBMED, Cochrane Library, EMBASE, OVID and Chinese BioMedical Literature & Retrieval System were searched using search terms “tranexamic acid”, “activated clotting time”, “cardiac surgery”, “randomized controlled trial” till May 7th, 2020, to identify all relevant randomized controlled trials (RCTs). SettingOperating room. PatientsCardiac surgical patients. InterventionsTXA or placebo. MeasurementsPrimary outcomes of interest included peri-operative ACT values. Secondary outcomes of interest include heparin dosage, protamine dosage, postoperative bleeding and blood transfusion. Main resultsSearch yielded 13 studies including 1168 patients, and 619 patients were allocated into Group TXA and 549 into Group Control (placebo). Meta-analysis suggested that, ACT values after heparinization [(WMD = −1.45; 95%CI: −12.52 to 15.43; P = 0.84)] and after protamine [(WMD = −1.18; 95%CI: −2.81 to 0.46; P = 0.16)] were comparable between Group TXA and Group Control, and that TXA did not influence heparin dose in adult patients [(WMD = 0.38; 95%CI: 0.30 to 0.46; P<0.00001) with no heterogeneity (I2 = 4%, P = 0.35)] and protamine dose for heparin reversal [(WMD = 5.23; 95%CI: −0.33 to 10.80; P = 0.07) with no heterogeneity (I2 = 0, P = 0.58)]. Meta-analysis also demonstrated that, TXA administration significantly reduced post-operative bleeding volume [(WMD = −126.33; 95%CI: −177.46 to −75.19; P < 0.0001), post-operative red blood cell (RBC) transfusion volume [(WMD = −71.86; 95% CI: −88.22 to −55.50; P < 0.00001), fresh frozen plasma (FFP) transfusion volume [(WMD = −13.83; 95% CI: −23.67 to −4.00; P = 0.006) and platelet concentrate (PC) transfusion volume [(WMD = −0.20; 95% CI: −0.29 to −0.10; P < 0.0001). ConclusionThis meta-analysis suggested that, TXA administration did not influence ACT value, heparin and protamine doses, but significantly reduced post-operative blood loss and transfusion requirement in cardiac surgical patients.

ECMOにより腹腔内出血が顕在化した胸骨圧迫後肝損傷の2例(Two cases of liver laceration and abdominal bleeding caused by CPR and ECMO)

要旨 蘇生処置の一環として行われる胸骨圧迫で，肋骨骨折や胸骨骨折の他に肝臓などの腹腔内臓器損傷が起こりうることが知られている。2013年6月から2018年6月末日までの5年間に当院のICUへ入室した患者を調べたところ，胸骨圧迫により肝損傷および腹腔内出血を来した症例は2例存在した。2症例ともにextracorporeal cardiopulmonary resuscitation（ECPR）を行い，ECMOにより胸骨圧迫後肝損傷が顕在化した。いずれの症例も蘇生後ECMOを離脱できたが，1症例は輸血療法で保存的に経過観察でき，もう1症例は緊急開腹止血術を要した。胸骨圧迫後の肝損傷がECMOにより顕在化する場合があるが，その早期認知のため超音波検査とCT検査が有用である。胸骨圧迫による外傷が懸念される症例では，ECMO開始後にその外傷が顕在化しうることに十分注意を払い，外傷が顕在化した際には早期に開腹止血術やtranscatheter arterial embolization（TAE）を考慮すべきである。若干の文献的考察を加え，本症例を報告する。

Can We Rely on the Activated Clotting Time to Measure Heparin Anticoagulation? A Clinical Evaluation of Two ACT Monitors

The sensitivity to heparin during cardiopulmonary bypass (CPB) is determined by patient-specific characteristics and is assessed by the whole blood activated clotting time (ACT). We aimed to examine reliability measures between two different ACT monitors using Bland–Altman analysis: bias should not exceed 50 ± 50 seconds for measurements performed during CPB or 10 ± 10 seconds before and after CPB. The ACT response should be linear in relation to the concentration of heparin in plasma. Twenty patients (n = 20) aged 20–80 years and admitted for coronary artery bypass surgery were enrolled to this clinical observational study.ACT values and antifactor Xa were sampled: 1) before induction of anesthesia, 2) after heparin bolus, 3) during CPB at the start of rewarming, 4) at weaning from CPB, and 5) after heparin reversal.The evaluation comprised the Hemostasis Management System Plus™ (HMS, Medtronic Inc., Minneapolis, MN) and i-STAT™ (Abbott, Point of Care Inc., Princeton, NJ). Bias for the HMS Plus™ vs. i-STAT™ was +105 ± 119 seconds for measurements during CPB and +2.8 ± 11.7 seconds before and after CPB. Associated limits of agreement for the observed bias were ±235 and ±23 seconds, respectively. Inter-device correlation of ACT values was .46 (p&lt; .001) during CPB; otherwise .48 (p= .02). Both devices produced ACT values unrelated (&lt;10%) to the measured heparin concentration. The use of multivariable regression analysis demonstrated an independent association between the ACT measurement and hematocrit, however, not with the plasma concentration of heparin. ACT monitors demonstrate unacceptable bias differences, combined with wide limits of agreement. The ACT response correlated with hematocrit, but not with the actual heparin concentration.

Intra-procedural anticoagulation and post-procedural hemoglobin fall in atrial fibrillation ablation with minimally interrupted direct oral anticoagulants: comparisons across 4 drugs.

Thromboembolic or hemorrhagic complications related to atrial fibrillation (AF) ablation are rare, and thus, it is difficult to compare their frequency across different direct oral anticoagulants (DOACs). We aimed to compare the intra-ablation blood coagulability and post-procedural hemoglobin fall as alternatives to those complications across 4 DOACs. We enrolled AF patients younger than 65years old in 3 cardiovascular centers who skipped a single dose of apixaban, dabigatran, edoxaban, and rivaroxaban, prior to the ablation. Endpoints included the activated clotting time (ACT), heparin requirement during the ablation, and drop in the hemoglobin level 24h after the procedure. The time-course curves of the ACT differed significantly across the patients with apixaban (N = 113), dabigatran (N = 130), edoxaban (N = 144), and rivaroxaban (N = 81), with its highest level in the dabigatran group (P < 0.001). The average ACT was greater in the dabigatran group than in the other groups (312.3 ± 34, 334.4 ± 44, 308.1 ± 41, and 305.8 ± 34.7s; P < 0.001). A significant difference was noted in total heparin requirement across the patient groups (3990.2 ± 1167.9, 3890.4 ± 955.3, 4423.8 ± 1051.6, and 3972 ± 978.7U/m2/h; P < 0.001), with its greatest amount in the edoxaban group. The reduction in the hemoglobin level was similar (- 0.93 ± 0.92, - 0.88 ± 0.79, - 0.89 ± 0.97, - 0.95 ± 1.23g/dL; P = 0.94). No inter-group difference was noted in the rate of major or minor bleedings (0.9%, 2.3%, 1.4%, and 3.7%; P = 0.51), and no thromboembolic events were encountered. A difference in DOACs may have an impact on intra-ablation anticoagulation; however, it may not be on the procedural blood loss in the setting of a single skip.

A Standardized Bolus of 5 000 IU of Heparin Does not Lead to Adequate Heparinization during Non-cardiac Arterial Procedures

In non-cardiac arterial procedures (NCAP), heparin is administered to prevent arterial thromboembolic complications (ATEC). Heparin has a nonpredictable effect in the individual patient, also known as variation in heparin sensitivity. Various dosing protocols are in use, but the optimal dose is currently still unknown. A standardized bolus of 5 000 IU heparin is most frequently used by vascular surgeons and interventional radiologists. The activated clotting time (ACT) is an established method to measure the level of anticoagulation, but has, until now, not gained widespread use in NCAP. The purpose of this study was to evaluate the anticoagulant effect during NCAP of a standardized bolus of 5 000 IU heparin by measuring the ACT. In this prospective study, 190 patients undergoing NCAP were enrolled between December 2016 and September 2018. The ACT was measured during open and endovascular/hybrid procedures. All patients received a standardized bolus of 5 000 IU heparin. The ACT was measured by the Hemostasis Management System Plus (HMS Plus, Medtronic®), before, 5minutes after administration of heparin, and every 30minutes thereafter. The primary outcome was periprocedural ACT values measured. Secondary outcomes were ATEC and hemorrhagic complications. A large individual patient variability in the response to heparin was found. The mean baseline ACT in all patients was 129±18s., and the mean ACT 5minutes after the initial bolus of heparin was 191±36s. After the initial dose of 5 000 IU heparin 60 (33%) and 10 (6%) patients reached an ACT of 200 and 250s., respectively. Despite the use of heparin, ATEC occurred in 17 patients (9%). The lowest number of ATEC occurred in the group of patients with an ACT between 200 and 250s. A standardized bolus of 5 000 IU heparin does not lead to adequate and safe heparinization in non-cardiac arterial procedures. Patient response to heparin shows a large individual variability. Therefore, routine ACT measurements are necessary to ascertain adequate anticoagulation. Further research is needed to investigate if heparin dosing based on the ACT could result in less arterial thromboembolic complications, without increasing hemorrhagic complications.

Percutaneous Coronary Intervention With an Initial Bolus of Low-Dose Heparin in Biomarker-Negative Patients

ObjectivesThe safety and efficacy of an initial intravenous bolus of low-dose heparin (40 IU/kg) was evaluated in biomarker negative patients undergoing percutaneous coronary intervention (PCI). BackgroundA bolus of 70–100 IU/kg of heparin is currently recommended for patients undergoing PCI. However, the ideal dose of heparin has not been evaluated in a randomized trial. The higher dose of 100 IU/kg may increase the risk of bleeding. An initial bolus of low-dose heparin may be advantageous to avoid supratherapeutic activating clotting times (ACT) while still allowing for the administration of additional heparin if the ACT is subtherapeutic. MethodsFrom January 2008 to February 2020, 904 patients undergoing elective transfemoral PCI received an initial bolus of 40 IU/kg of heparin. Patients who underwent transradial PCI were not included. Patients were routinely pretreated with dual antiplatelet therapy. The primary end point was the composite of cardiac death, myocardial infarction (MI), urgent target vessel revascularization (TVR) for ischemia, or major bleeding within 30 days after PCI. ResultsThe initial mean activating clotting time was 235.4 ± 26.6 s. The clinical event rates were low: the primary end point occurred in 5.3%, cardiac death in 1.0%, MI in 3.1%, urgent TVR in 0.7% and major bleeding in 1.9%. Stent thrombosis was uncommon (0.2%). No patients developed profound thrombocytopenia. Three patients (0.3%) had acute limb ischemia that required revascularization. ConclusionAn initial strategy of low-dose heparin is associated with low ischemic and bleeding complications in biomarker negative patients who undergo transfemoral PCI.

High Thrombus Burden in Patients With COVID-19 Presenting With ST-Segment Elevation Myocardial Infarction

BackgroundCoronavirus disease-2019 (COVID-19) is thought to predispose patients to thrombotic disease. To date there are few reports of ST-segment elevation myocardial infarction (STEMI) caused by type 1 myocardial infarction in patients with COVID-19. ObjectivesThe aim of this study was to describe the demographic, angiographic, and procedural characteristics alongside clinical outcomes of consecutive cases of COVID-19–positive patients with STEMI compared with COVID-19–negative patients. MethodsThis was a single-center, observational study of 115 consecutive patients admitted with confirmed STEMI treated with primary percutaneous coronary intervention at Barts Heart Centre between March 1, 2020, and May 20, 2020. ResultsPatients with STEMI presenting with concurrent COVID-19 infection had higher levels of troponin T and lower lymphocyte count, but elevated D-dimer and C-reactive protein. There were significantly higher rates of multivessel thrombosis, stent thrombosis, higher modified thrombus grade post first device with consequently higher use of glycoprotein IIb/IIIa inhibitors and thrombus aspiration. Myocardial blush grade and left ventricular function were significantly lower in patients with COVID-19 with STEMI. Higher doses of heparin to achieve therapeutic activated clotting times were also noted. Importantly, patients with STEMI presenting with COVID-19 infection had a longer in-patient admission and higher rates of intensive care admission. ConclusionsIn patients presenting with STEMI and concurrent COVID-19 infection, there is a strong signal toward higher thrombus burden and poorer outcomes. This supports the need for establishing COVID-19 status in all STEMI cases. Further work is required to understand the mechanism of increased thrombosis and the benefit of aggressive antithrombotic therapy in selected cases.

Factors influencing activated clotting time following heparin administration for the initiation of cardiopulmonary bypass.

Initiation of cardiopulmonary bypass (CPB) for open-heart surgery requires that heparin be administered and reach an adequate value of activated clotting time (ACT). We previously introduced a new heparin formula that considered the preoperative ACT. In this study, we determined other factors affecting ACT. Adult patients who underwent cardiac surgery using CPB were divided into two groups according to their ACT value after the initial administration of heparin during surgery. ACT above 450s was defined as "Reach", and this group was compared to the "Short" group with ACT below 450s. The Reach and Short groups included 334 (64.7%) and 182 (35.3%) cases, respectively. Univariate analysis indicated that preoperative heparin use, age ≥ 80years, New York Heart Association classification 4, white blood cell counts above the higher limit, hematocrit below the lower limit, platelet cell counts below the lower limit, low albumin levels, moderate renal dysfunction, high C-reactive protein levels, high brain natriuretic peptide levels, and moderate deterioration of left ventricular ejection fraction were associated with the effects of heparin. Multivariate analysis revealed that age ≥ 80years (odds ratio [OR] 2.53, 95% confidence interval [95%CI] 1.41-5.24), New York Heart Association classification 4 (OR = 4.44, 95%CI 1.59-15.35), and platelet count below the lower limit (OR 0.37, 95%CI 0.31-0.85) were associated with the effects of heparin. Old age, heart failure, and lower platelet counts affected heparin activity. The dose of heparin should be considered in those patients to reach the target ACT.

First experience in implantation of a mechanical circulatory support device based on a disk-type pump: an acute experiment

Objective: to carry out the implantation of an artificial left ventricle of the heart based on a disk-type pump in an acute experiment on a large mammal (mini-pig). Materials and methods. To test the surgical technique of implantation and assess the biocompatibility of the apparatus for mechanical support of blood circulation based on a viscous friction pump, an acute experiment was conducted on an animal. A large mammal (mini-pig weighing 90 kg) was used as an experimental model. The implantation of the pump was performed extracorporeally according to the scheme «the apex of the left ventricle – the descending thoracic aorta». During the experiment, invasive blood pressure, central venous pressure, cardiac arrhythmias, body temperature, blood gas composition, activated coagulation time were monitored. Under the control of transesophageal echocardiography, the pump operation mode was set with parameters – speed 2400–2600, productivity 4 ± 0.5 l/min, average IAD – 70–80 mm Hg. Results. In the course of the experiment, the fundamental possibility of using the developed disk-type pump as a device for supporting blood circulation was proved. For 4 hours, the pump provided adequate hemodynamic parameters with an average productivity of 4 ± 0.5 l/min and 2500 rpm. After 4 hours of operation of the pump in the conditions of inactivated heparin (AST – 114 sec), no blood clots were found between the pump disks. Conclusion The hemodynamics feature of the disk pump allows you to develop sufficient performance parameters to ensure adequate blood circulation. The mechanism of action of the «boundary layer» minimizes the risk of blood clots in the pump cavity. However, the topographic and anatomical features of the pig’s body do not allow experiments with a long observation period.

Transfusion characteristics and hemostatic conditions in octogenarians undergoing emergency surgery for acute aortic dissection: a retrospective study

BackgroundThe number of elderly patients undergoing elective as well as emergent cardiac surgery is increasing. Octogenarian and older patients undergoing surgery for acute type A aortic dissection (AAD) have a significantly higher risk of postoperative mortality than younger patients. Hemostasis is difficult in octogenarians with AAD. However, few studies have investigated perioperative blood transfusion volumes and hemostatic conditions in patients undergoing AAD surgery. We retrospectively investigated whether these factors differed between octogenarians and younger patients with AAD.MethodsThe records of 207 patients who underwent emergency surgery for AAD were reviewed between 2008 and 2014. We compared the total volumes of transfused blood components (red blood cell concentrate, fresh frozen plasma, platelets concentrate, and cryoprecipitate), perioperative blood coagulation test results (prothrombin time-international normalized ratio, activated partial thrombin time, and activated coagulation time), and intensive care unit and hospital stay durations between octogenarians (n = 33) and patients < 80 years old (n = 170).ResultsA significantly greater volume of red blood cell concentrates was transfused in octogenarians than in patients < 80 years old. Isolated prolonged activated partial thromboplastin time was observed in octogenarian patients. Duration of hospital stays was significantly longer in octogenarians than in patients < 80 years old.ConclusionsOctogenarians required more red blood cells during surgery for AAD and exhibited isolated APTT prolongation.