Alternative Anticoagulation Management Strategies for the Patient With Heparin-Induced Thrombocytopenia Undergoing Cardiac Surgery

The addition of Tirofiban infusion to heparin for intraoperative heparin resistance associated with Marfan Syndrome

Marfan syndrome classically presents with aortic root aneurysms. Aortic ectasia causes diverse blood flow alterations, influencing the behavior of coagulation factors and platelet activity. Heparin resistance has also been reported associated with Marfan Syndrome in a small number of patients, probably due to antithrombin III (ATIII) deficiency or various mutations. The ascending aorta and the aortic valve are replaced with prosthetic material during Bentall- de Bonno procedures. Resistance to anticoagulation during extracorporeal circulation, represents a significant challenge for both anesthesiologists and the surgical team. Resistance to heparin was observed in a patient with Marfan syndrome undergoing a Bentall procedure. ATIII concentrate was not available, and ACT did not increase despite high doses of heparin. An alternate anticoagulation approach was used successfully.

High-Dose Dabigatran Is an Effective Anticoagulant for Simulated Cardiopulmonary Bypass Using Human Blood

BACKGROUND

Currently no ideal alternative exists for heparin for cardiopulmonary bypass (CPB). Dabigatran is a direct thrombin inhibitor for which a reversal agent exists. The primary end point of the study was to explore whether Dabigatran was an effective anticoagulant for 120 minutes of simulated CPB.

METHODS

The study was designed in 2 sequential steps. Throughout, human blood from healthy donors was used for each experimental step. Initially, increasing concentrations of Dabigatran were added to aliquots of fresh whole blood, and the anticoagulant effect measured using kaolin/tissue factor-activated thromboelastography (rapidTEG). The dynamics of all thromboelastography (TEG) measurements were studied with repeated measures analysis of variance (ANOVA). Based on these data, aliquots of blood were treated with high-concentration Dabigatran and placed in a Chandler loop as a simple ex vivo bypass model to assess whether Dabigatran had sufficient anticoagulant effects to maintain blood fluidity for 2 hours of continuous contact with the artificial surface of the PVC tubing. Idarucizumab, humanized monoclonal antibody fragment, was used to verify the reversibility of Dabigatran effects. Finally, 3 doses of Dabigatran were tested in a simulated CPB setup using a heart-lung machine and a commercially available bypass circuit with an arteriovenous (A-V) loop. The primary outcome was the successful completion of 120 minutes of simulated CPB with dabigatran anticoagulation, defined as lack of visible thrombus. Thromboelastographic reaction (R) time was measured repeatedly in each bypass simulation, and the circuits were continuously observed for clot. Scanning Electron Microscopy (SEM) was used to visualize fibrin formation in the filters meshes during CPB.

RESULTS

In in vitro blood samples, Dabigatran prolonged R time and reduced the dynamics of clot propagation (as measured by speed of clot formation [Angle], maximum rate of thrombus generation [MRTG], and time to maximum rate of thrombus generation [TMRTG]) in a dose-dependent manner. In the Chandler Loop, high doses of Dabigatran prevented clot formation for 120 minutes, but only at doses higher than expected. Idarucizumab decreased R time and reversed anticoagulation in both in vitro and Chandler Loops settings. In the A-V loop bypass simulation, Dabigatran prevented gross thrombus generation for 120 minutes of simulated CPB.

CONCLUSIONS

Using sequential experimental approaches, we showed that direct thrombin inhibitor Dabigatran in high doses maintained anticoagulation of blood for simulated CPB. Idarucizumab reduced time for clot formation reversing the anticoagulation action of Dabigatran.

An Implanted Magnetic Microfluidic Pump for In Vivo Bone Remodeling Applications

Modulations of fluid flow inside the bone intramedullary cavity has been found to stimulate bone cellular activities and augment bone growth. However, study on the efficacy of the fluid modulation has been limited to external syringe pumps connected to the bone intramedullary cavity through the skin tubing. We report an implantable magnetic microfluidic pump which is suitable for in vivo studies in rodents. A compact microfluidic pump (22 mm diameter, 5 mm in thickness) with NdFeB magnets was fabricated in polydimethylsiloxane (PDMS) using a set of stainless-steel molds. An external actuator with a larger magnet was used to wirelessly actuate the magnetic microfluidic pump. The characterization of the static pressure of the microfluidic pump as a function of size of magnets was assessed. The dynamic pressure of the pump was also characterized to estimate the output of the pump. The magnetic microfluidic pump was implanted into the back of a Fischer-344 rat and connected to the intramedullary cavity of the femur using a tube. On-demand wireless magnetic operation using an actuator outside of the body was found to induce pressure modulation of up to 38 mmHg inside the femoral intramedullary cavity of the rat.

An infrequent complication of a not so infrequent disease. Hit by HIT

Heparin-induced thrombocytopenia is not uncommon in cardiac surgery. Thrombosis is the most frequent complication. A 77-year-old man suffered cardiac arrest due to right coronary emboli. Transesophageal echocardiography revealed tissue valve thrombosis. He required support with an extracorporeal membrane oxygenator that also thrombosed. Heparin-induced thrombocytopenia was diagnosed, and anticoagulation was switched to argatroban. Heparin- induced thrombocytopenia normally presents as vascular thrombosis. In this case, the first symptom was tissue valve thrombosis causing an acute coronary syndrome. It is not an uncommon complication and should be considered if unexpected thrombosis and a sudden drop in platelet count develops after heparin exposure.

The Use of Cangrelor and Heparin for Anticoagulation in a Patient Requiring Pulmonary Thromboendarterectomy Surgery with Suspected Heparin-Induced Thrombocytopenia

The management of heparin-induced thrombocytopenia (HIT) in the perioperative period for patients undergoing cardiac surgery requiring cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) can be a challenging clinical scenario. Once a diagnosis of HIT has been established, heparin products typically are avoided and alternative therapies for anticoagulation are started. Alternative anticoagulation strategies for CPB are limited and often have various pharmacokinetic profiles that may lead to increased perioperative bleeding. Historically the use of a GPIIb/IIIa inhibitor, such as tirofiban, followed by unfractionated heparin (UFH) is the typical alternative for surgeries requiring DHCA in patients with HIT at the authors' institution. This article presents a case in which cangrelor followed by UFH was used in a 20-year-old patient with suspected HIT and chronic thromboembolic pulmonary hypertension undergoing pulmonary thromboendarterectomy surgery requiring CPB and DHCA. Due to the frequency of significant postoperative bleeding encountered when using tirofiban and UFH, it was decided to attempt to block platelet aggregation with significantly shorter-acting cangrelor. The authors hypothesized that cangrelor would reduce the risk of significant bleeding compared with tirofiban because of its favorable pharmacokinetics. Specifically, cangrelor has a short elimination half-life of 3 to 6 minutes, and its elimination is not altered by renal and hepatic impairment. This case report discusses the pathophysiology of HIT, the alternative anticoagulants used for HIT type II in pulmonary thromboendarterectomy, and the potential of cangrelor in conjunction with UFH to be a favorable option for patients in similar clinical scenarios.

Argatroban for an alternative anticoagulant in HIT during ECMO

Background

Extracorporeal membrane oxygenation (ECMO) have become more frequently used in daily ICU practice, heparin-induced thrombocytopenia (HIT) is a rare but life-threatening complication while on extracorporeal membrane oxygenation (ECMO). HIT confirmation directly impacts on anticoagulant strategy requiring no delay unfractionated heparin discontinuation to be replaced by alternative systemic anticoagulant treatment.

Case presentation

We report two clinical cases of HIT occurring during ECMO in various settings with subsequent recovery with argatroban and provide literature review to help physicians treat HIT during ECMO in clinical daily practice.

Conclusions

HIT during ECMO is uncommon, and despite the absence of recommendation, argatroban seems to be an appropriate and safe therapeutic option. Finally, there are not enough arguments favouring routine circuit change in the event of HIT during ECMO

Heparin-Induced Thrombocytopenia: A Comprehensive Clinical Review

Heparin-induced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to low-molecular weight heparin. In this comprehensive review, the authors highlight heparin-induced thrombocytopenia's risk factors, clinical presentation, pathophysiology, diagnostic principles, and treatment. The authors place special emphasis on the management of patients requiring procedures using cardiopulmonary bypass or interventions in the catheterization laboratory. Clinical vigilance of this disease process is important to ensure its recognition, diagnosis, and treatment. Misdiagnosis of the syndrome, as well as misunderstanding of the disease process, continues to contribute to its morbidity and mortality.

Ancrod revisited: viscoelastic analyses of the effects of Calloselasma rhodostoma venom on plasma coagulation and fibrinolysis

Fibrinogen depletion via catalysis by snake venom enzymes as a therapeutic strategy to prevent or treat thrombotic disorders was utilized for over four decades, with ancrod being the quintessential agent. However, ancrod eventually was found to not be of clinical utility in large scale stroke trial, resulting in the eventual discontinuation of the administration of the drug for any indication. It was hypothesized that ancrod, possessing thrombin-like activity, may have unappreciated robust coagulation kinetics. Using thrombelastographic methods, a comparison of equivalent tissue factor initiated thrombin generation and Calloselasma rhodostoma venom (rich in ancrod activity) on plasmatic coagulation kinetics was performed. The venom resulted in thrombi that formed nearly twice as fast compared to thrombin formed clots, and there was no difference in fibrinolytic kinetics initiated by tissue-type plasminogen activator. In plasma containing iron and carbon monoxide modified fibrinogen, which may be found in patients at risk of stroke, the coagulation kinetic differences observed with venom was still more vigorous than that seen with thrombin. These phenomena may provide insight into the clinical failure of ancrod, and may serve as an impetus to revisit the concept of fibrinogen depletion via fibrinogenolytic enzymes, not those with thrombin-like activity.

An Anti-Coagulation Conundrum: Implantation of Total Artificial Heart in a Patient with Heparin-Induced Thrombocytopenia Type II

BACKGROUND Heparin-induced thrombocytopenia (HIT) is a rare but life-threatening complication of heparin administration. It can present a major clinical dilemma for physicians caring for patients requiring life-saving urgent or emergent cardiac surgery. Studies have been published examining the use of alternative anticoagulants for patients undergoing cardiopulmonary bypass (CPB), however, evidence does not clearly support any particular approach. Presently, there are no large-scale, prospective randomized studies examining the impact of alternative anticoagulants on clinical outcomes for HIT-positive patients requiring cardiac surgery. CASE REPORT We present the case of a patient who underwent SynCardia Total Artificial Heart (TAH) implantation following a recent left ventricular assist device (LVAD) placement. The patient was receiving argatroban for type II HIT with anuric renal failure, and developed a thrombus which occluded the inflow cannula of the LVAD. Based on a published study and after establishing consensus with the surgical, anesthesiology, perfusion, and hematology teams, we decided to use tirofiban as an antiplatelet agent to inhibit the platelet aggregation induced by heparin, and ultimately used heparin as the anticoagulant for cardiopulmonary bypass. CONCLUSIONS When selecting anticoagulation for a HIT-positive patient requiring CPB, so that benefits outweigh risks, it is of paramount importance that the decision be based on a multitude of factors. The team caring for the patient should have a shared mental model and be familiar with the pharmacology, devices used, and local practices. These three elements should be integrated with patient-specific comorbidities along with local monitoring capabilities to ensure safe, efficient patient care.

Cardiopulmonary Bypass Without Heparin

Due to familiarity, short half-life, ease of monitoring, and the availability of a reversal agent, heparin remains the anticoagulant of choice for cardiac operations requiring cardiopulmonary bypass (CPB). However, occasionally patients require CPB but should not receive heparin, most often because of acute or subacute heparin-induced thrombocytopenia (HIT). In these cases, if it is not feasible to wait for the disappearance of HIT antibodies, an alternative anticoagulant must be selected. A number of non-heparin anticoagulant options have been explored. However, current recommendations suggest the use of a direct thrombin inhibitor such as bivalirudin. This review describes the use of heparin alternatives for the conduct of CPB with a focus on the direct thrombin inhibitors.

Heparinized and Saline Solutions in the Maintenance of Arterial and Central Venous Catheters After Cardiac Surgery

Background:

Heparinized saline solution is used to prevent occlusion in the arterial catheters and central venous pressure monitoring catheters. Even at low dose, heparin administration can be associated with serious complications. Normal saline solution can maintain patency of arterial catheters and central venous pressure monitoring catheters.

Objectives:

The current study aimed to compare the efficacy of normal saline with that of heparinized one to maintain patency of arterial and central venous catheters after cardiac surgery.

Patients and Methods:

In the current randomized controlled trial, 100 patients, with an age range of 18 - 65 years of valve and coronary artery surgery were studied in Rajaie heart center, Tehran, Iran. Patients were randomized to receive either heparinized saline (n = 50) or normal saline flush solutions (n = 50). In the study, arterial catheters and central venous pressure monitoring catheters were daily checked for any signs of occlusion in three postoperative days as primary end-point of the study.

Results:

According to the information obtained from the study, four (8%) arterial catheters in the saline group (P value: 0.135) and three (6%) arterial catheters in the heparin group (P value = 0.097) were obstructed. Statistical analysis showed that the incidence of obstruction and changes in all other parameters between the two groups during the three-day follow-up was not significant (all P values > 0.05).

Conclusions:

It seems that there is no difference in the use of heparinized and normal saline solutions to prevent catheter occlusion of arterial and central venous pressure.

Avoiding Heparinization of Arterial Line and Maintaining Acceptable Arterial Waveform After Cardiac Surgery: A Randomized Clinical Trial

Background:

Invasive and continuous blood pressure (BP) monitoring is crucial after cardiac surgery. Accuracy of BP measurement mostly depends on patency of arterial catheter and acceptable waveform. Heparinized saline flush usually used for this purpose may be accompanied by potential heparin adverse effects.

Objectives:

The aim of this study was to compare heparinized and non-heparinized saline flush to maintain acceptable arterial waveform after cardiac surgery.

Materials and Methods:

In a double blind randomized trial study, 100 patients undergoing elective cardiac surgery were randomized to using heparinized (n = 50) or non-heparinized (normal) saline flush (n = 50) to maintain patency of arterial catheter after operation. Indwelling arterial catheters were checked daily for acceptable arterial waveform for three days as primary outcome measures.

Results:

Frequency of acceptable arterial waveform ranged from 66% to 80%, in first, second and third postoperative days. There were no statistically significant differences between heparinized and non-heparinized saline groups regarding acceptable arterial waveforms in all the three postoperative days (all P values > 0.05).

Conclusions:

Using non-heparinized normal saline is suitable to maintain acceptable arterial waveform for short-term (three days) after adult cardiac surgery considering potential adverse effects of heparin.

Probing the coagulation pathway with aptamers identifies combinations that synergistically inhibit blood clot formation

Coordinated enzymatic reactions regulate blood clot generation. To explore the contributions of various coagulation enzymes in this process, we utilized a panel of aptamers against factors VIIa, IXa, Xa, and prothrombin. Each aptamer dose-dependently inhibited clot formation, yet none was able to completely impede this process in highly procoagulant settings. However, several combinations of two aptamers synergistically impaired clot formation. One extremely potent aptamer combination was able to maintain human blood fluidity even during extracorporeal circulation, a highly procoagulant setting encountered during cardiopulmonary bypass surgery. Moreover, this aptamer cocktail could be rapidly reversed with antidotes to restore normal hemostasis, indicating that even highly potent aptamer combinations can be rapidly controlled. These studies highlight the potential utility of using sets of aptamers to probe the functions of proteins in molecular pathways for research and therapeutic ends.

Simultaneous comparison of thrombogenic reactions to different combinations of anticoagulants, activated clotting times, and materials

Thrombogenic reactions under multiple interactions of pharmacological agents, doses, and materials have not been well understood yet. The aim of this study was to investigate the ability to simultaneously compare thrombogenic reactions to different combinations of anticoagulants, doses, and blood-contacting materials, in a single human blood using an in vitro test method. Four venous blood samples were drawn from each of six healthy volunteers into syringes that contained two different amounts of heparin and argatroban to set the activated clotting time (ACT) to approximately 200 or 500 s, respectively. The four blood samples from each volunteer were immediately poured into two clinical-grade extracorporeal circulation tubes: a polyvinyl chloride (PVC) tube and a poly(2-methoxyethyl acrylate)-coated (PMEA) PVC tube. These tubes with an inner diameter of 12.7 mm were rotated at 183 rpm in a 37°C chamber for 10 min. The results indicated that the in vitro thrombogenicity test method was capable of assessing differences in platelet factor 4 and β-thromboglobulin increases among different combinations of the two materials, two anticoagulants, and two ACTs. Higher amounts of total plasma proteins were absorbed on PVC tubes than on PMEA-coated tubes when using the same anticoagulant and dose. These data elucidate that the in vitro thrombogenicity test method is useful for the simultaneous quantitative evaluation of the influences of various combinations of materials, pharmacological agents, and doses on thrombogenicity in a single human blood.

Challenges encountered with argatroban anticoagulation during cardiopulmonary bypass

Use of argatroban as an alternative to heparin during cardiopulmonary bypass (CPB) in patients with heparin-induced thrombocytopenia has gained some attention in the past two decades. Dosing of argatroban during CPB is complex due to lack of complete understanding of its pharmacokinetic profile and the various elements during CPB that may alter its plasma levels. We report a case where the challenges in dosing argatroban led to failure to provide adequate anticoagulation during CPB, as evidenced by clot formation in the oxygenator, and extensive bleeding in the postoperative period.

Lepirudin as an alternative to "heparin allergy" during cardiopulmonary bypass

A treatment strategy of a difficult and unusual problem is presented. We are reporting a case of a patient who had a documented allergy to heparin and required Cardiac surgery for an ASD closure. The anticoagulation regime used during cardiopulmonary bypass was lepirudin based. This report indicates that r-hirudin provides effective anticoagulation, however unless ECT is monitoring, post operative hemorrhage is encountered. Therefore this case is unique not only because of its rarity but also by the fact that it presents the caveats encountered when ECT is not available.

Update in hematology: heparin-induced thrombocytopenia and bivalirudin

Heparin-induced thrombocytopenia (HIT) is important because it is common, and it significantly increases mortality after cardiac surgery. Although thrombocytopenia after cardiac surgery is common, it predicts serious adverse outcome when it is severe. Despite the high prevalence of heparin/platelet factor 4 antibodies in cardiac surgical patients, they typically do not indicate a higher perioperative risk. Recent evidence suggests, however, that when these antibodies are in the immunoglobulin M class, there is an increased risk of nonthrombotic adverse outcomes after cardiac surgery. According to the guidelines from the American College of Chest Physicians, patients with HIT require parenteral anticoagulation with a direct thrombin inhibitor such as lepirudin, argatroban, or bivalirudin. The transition to oral anticoagulation must be undertaken cautiously and only after the platelet count has recovered. Patients with a remote history of HIT can have cardiac surgery safely with unfractionated heparin. Patients with clinically active HIT who require cardiac surgery before the resolution of the HIT preferably should be anticoagulated with bivalirudin, dosed according to body weight and the goal-activated coagulation time. Given that bivalirudin is an established alternative to heparin as a thrombin inhibitor for cardiac surgery, it is likely that future trials will investigate which anticoagulant confers better outcomes after cardiac surgery, as is the case in percutaneous coronary intervention.

Evaluation of antiplatelet effects of a modified protocol by platelet aggregation in patients undergoing "one-stop" hybrid coronary revascularization

"One-stop" hybrid coronary revascularization has emerged to be a reliable and attractive alternative for selected patients with multivessel coronary artery disease. However, the optimal antiplatelet regimen of the one-stop hybrid procedure still remains controversial. We modified the antiplatelet protocol in order to reduce the risk of perioperative bleeding and maximally inhibit platelet activity. This study sought to investigate whether the inhibition of platelet activity by this modified antiplatelet protocol is comparable with the conventional protocol widely used and recommended in percutaneous coronary interventions (PCI). Twenty three patients undergoing one-stop hybrid procedure and 20 patients undergoing conventional PCI were enrolled in this prospective study. The modified antiplatelet protocol included perioperative use of aspirin; clopidogrel was administered immediately before PCI with a 300 mg loading dose, followed by a maintenance dose of 75 mg/day for 12 months. Blood samples were obtained before the operation and 2 hours, day 1 and day 3 after operation. Platelet aggregation was induced with: 1) arachidonic acid (AA) (final concentration 0.5 mmol/L) to assess the efficacy of aspirin; 2) adenosine diphosphate (ADP) (final concentration 10 micromol/L) to assess the specific efficacy of clopidogrel. Platelet counts were statistically lower in the hybrid group than in the PCI control group (p = 0.0018) on day 1 after operation. AA-induced platelet aggregation increased significantly in comparison with the preoperative baseline values (p = 0.0079) and the PCI control group (p = 0.0023) on day 1 after operation. ADP-induced platelet aggregation gradually decreased in the hybrid group, and achieved similar platelet inhibition with the PCI group on 2 hours and day 1 after operation. No major adverse clinical events such as death, perioperative myocardial infarction, stent thrombosis or reoperation for bleeding occurred in both groups within 30 days after procedure. These results demonstrate that our modified antiplatelet therapy can sufficiently inhibit platelet activity similarly as the conventional protocol for PCI early after operation. Thus, this modified protocol, with continuous use of aspirin and intraoperative administration of loading dose clopidogrel, might be a safe and effective antiplatelet strategy for the one-stop hybrid coronary revascularization.

Successful on-pump coronary artery bypass without using protamine

A 48-year-old woman presented with a history of angina and breathlessness on exertion. She was diagnosed to have critical left main stem coronary artery disease along with a blocked right coronary artery. She was also allergic to protamine. After multidisciplinary consultation, it was decided to use heparin without protamine for reversal. She underwent successful on-pump coronary artery bypass grafting (CABG) without excessive blood loss. The disadvantages were a longer total operating time and the use of blood products to achieve normal coagulation. This case report describes the successful management of this complex problem.

Strategies in heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an uncommon condition that may confront cardio-thoracic surgeons with difficult problems. The underlying cause of HIT is the formation of antibodies against platelet factor 4/heparin complexes, leading to platelet activation and intravascular platelet aggregation. HIT occurs following heparin administration usually with a time delay of 5-10 days. Clinical suspicion and laboratory tests for platelet-activating antibodies are the cornerstone of diagnosis. Appropriate strategies in HIT are stopping heparin and use of alternative anticoagulants. In addition, surgery with extracorporeal circulation (ECC) should be postponed whenever possible or alternative anticoagulants have to be used during ECC.

New parenteral anticoagulants in development

The therapeutic armamentarium of parenteral anticoagulants available to clinicians is mainly composed by unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), fondaparinux, recombinant hirudins (i.e. bivalirudin, desirudin, lepirudin) and argatroban. These drugs are effective and safe for prevention and/or treatment of thromboembolic diseases but they have some drawbacks. Among other inconveniences, UFH requires regular anticoagulant monitoring as a result of variability in the anticoagulant response and there is a risk of serious heparin-induced thrombocytopaenia (HIT). LMWH, fondaparinux and recombinant hirudins are mainly cleared through the kidneys and their use in patients with severe renal insufficiency may be problematic. LMWH is only partially neutralized by protamine while fondaparinux and recombinant hirudins have no specific antidote. Novel anticoagulants in development for parenteral administration include new indirect activated factor Xa (FXa) inhibitors (idrabiotaparinux, ultra-low-molecular-weight heparins [semuloparin, RO-14], new LMWH [M118]), direct FXa inhibitors (otamixaban), direct FIIa inhibitors (flovagatran sodium, pegmusirudin, NU172, HD1-22), direct FXIa inhibitors (BMS-262084, antisense oligonucleotides targeting FXIa, clavatadine), direct FIXa inhibitors (RB-006), FVIIIa inhibitors (TB-402), FVIIa/tissue factor inhibitors (tifacogin, NAPc2, PCI-27483, BMS-593214), FVa inhibitors (drotrecogin alpha activated, ART-123) and dual thrombin/FXa inhibitors (EP217609, tanogitran). These new compounds have the potential to complement established parenteral anticoagulants. In the present review, we discuss the pharmacology of new parenteral anticoagulants, the results of clinical studies, the newly planned or ongoing clinical trials with these compounds, and their potential advantages and drawbacks over existing therapies.

Bivalirudin for patients with heparin-induced thrombocytopenia undergoing cardiovascular surgery

OBJECTIVE

To evaluate the use of bivalirudin in patients with heparin-induced thrombocytopenia (HIT) undergoing cardiovascular surgery.

DATA SOURCES

Relevant information was identified through a search of MEDLINE (1966-April 2008), International Pharmaceutical Abstracts (1960-April 2008), and Cochrane Databases (publications archived until April 2008) using the terms bivalirudin, heparin-induced thrombocytopenia, and cardiovascular surgery.

STUDY SELECTION AND DATA EXTRACTION

Prospective and retrospective studies, case reports, and case series in adults were eligible for inclusion if bivalirudin had been used in a patient with known HIT undergoing any cardiovascular surgical procedure other than percutaneous coronary intervention.

DATA SYNTHESIS

Two small, open-label, multicenter clinical trials were identified that evaluated treatment with bivalirudin in patients with HIT undergoing coronary artery bypass graft surgery. One looked at on-pump cardiopulmonary bypass (CPB), while the other looked at off-pump CPB. Procedural success was achieved at day 7 in 94% (n = 46) of patients in the on-pump CPB study and in 92% (n = 47) of patients in the off-pump CPB study. Dosing strategies varied between the 2 trials, with the on-pump study using a 1-mg/kg bivalirudin bolus followed by a 2.5-mg/kg/h infusion; the off-pump study used a 0.75-mg/kg bolus followed by a 1.75-mg/kg/h infusion. In addition, 10 case reports met the criteria to be included in the review and are summarized. In these cases, procedural success was reported using various bivalirudin doses in valve repair and replacement, right ventricular assist device implantation, and heart transplantation.

CONCLUSIONS

Growing data demonstrate procedural success with bivalirudin in patients with HIT undergoing cardiovascular surgery. However, bivalirudin dosing and goal-activated clotting times varied between the studies and case reports. Bivalirudin represents a viable alternative to heparin in patients with HIT undergoing cardiovascular surgery; however, further trials are warranted to identify optimal dosing and monitoring parameters.

Successful use of bivalirudin for superior vena cava recanalization and stent placement in a child with heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a potentially life-threatening, adverse effect of heparin therapy. Patients with this complication require an alternative approach to anticoagulation. Bivalirudin is a direct thrombin inhibitor with an efficacy comparable to that of heparin, a short half-life, and reduced bleeding complications in adults. We present the case of a 2-year-old boy with HIT Type II who underwent recanalization of an occluded superior vena cava and stent placement, utilizing bivalirudin as anticoagulant.

Cardiac anesthesia and surgery in geriatric patients

The average age of US population is steadily increasing, with more than 15 million people aged 80 and older. Coronary artery disease and degenerative cardiovascular diseases are particularly prevalent in this population. Consequently, an increasing number of elderly patients are referred for surgical intervention. Advanced age is associated with decreased physiologic reserve and significant comorbidity. Thorough preoperative assessment, identification of the risk factors for perioperative morbidity and mortality, and optimal preparation are critical in these patients. Age-related changes in comorbidities and altered pharmacokinetics and pharmacodynamics impacts anesthetic management, perioperative monitoring, postoperative care, and outcome. This article updates the age-related changes in organ subsystems relevant to cardiac anesthesia, perioperative issues, and intraoperative management. Early and late operative outcome in octogenarians undergoing cardiac surgery are reviewed. The data clearly indicate that no patient group is "too old" for cardiac surgery and that excellent outcomes can be achieved in selected group of elderly patients.