Danielle Blais

Effect of body mass index and device type on infection in left ventricular assist device support beyond 30 days

Infection as a complication of long-term left ventricular assist device (LVAD) support leads to significant morbidity and mortality. Obesity, a possible risk factor for other postoperative cardiovascular surgical site infections, is an increasingly prevalent condition among recipients of LVAD devices. We retrospectively analyzed 145 LVADs that remained in place beyond 30 days over a nine-year period at a single medical institution. Statistical analysis was carried out using univariate and multivariable logistic regression and chi(2)-testing where indicated. Body mass index (BMI) had no effect on the incidence of infectious outcomes regardless of age, gender, underlying pathogen or device type. This included the morbidly obese population as well (BMI >or=40). Independent of BMI, device type did have an effect, with the HeartMate XVE increasing the risk for infections [odds ratio (OR) 4.3 with 95% confidence interval (CI) 2.1-8.8, P=0.0001] and the HeartMate II reducing the risk (OR 0.21 with 95% CI 0.09-0.50, P=0.0001). The risk for infection after LVAD placement for long-term support is likely to be a multi-factorial phenomenon. BMI, including morbid obesity, does not appear to be a statistically significant relevant factor in determining that risk. Device type may have an effect, however, on risk of infection in long-term support.

Extracorporeal Membrane Oxygenation for Pandemic (H1N1) 2009

To the Editor: As the world struggles with the challenges of influenza A pandemic (H1N1) 2009, it is clear that treatment options for critically ill infected patients are suboptimal because deaths continue to be reported in otherwise young and healthy patients. Extracorporeal membrane oxygenation (ECMO) is an established therapeutic option for patients with medically refractory cardiogenic or respiratory failure. We describe the successful use of ECMO in a patient with complicated pneumonia and influenza A pandemic (H1N1) 2009 virus infection. Our patient, a 21-year-old woman who was 4 months postpartum, had poorly controlled insulin-dependent diabetes (hemoglobin A1C level 13.2 mg/dL). She sought treatment at another hospital after 3 days of respiratory symptoms, a productive cough after working in her garden, and a fever >103°F. Her condition rapidly deteriorated, and she required mechanical ventilation, vasoactive medications, and drotecogin-α (Xigris; Eli Lilly and Company, Indianapolis, IN, USA) for profound shock. The patient was then transferred to Ohio State University Medical Center on August 24, 2009; at admission she exhibited hypotension (83/43 mm Hg) and tachycardia (159 bpm), despite having received high doses of vasoactive medications (norepinephrine 1.0 µg/kg/min, phenylephrine 2.0 µg/kg/min). A transthoracic echocardiograph showed severe biventricular failure (ejection fraction 5%–10%); peak tropinin level was 6 mg/dL. Arterial blood gas confirmed metabolic acidosis (pH 7.12, partial carbon dioxide pressure [pCO2] 48 mm Hg, pO2 117 mm Hg, HCO3 15.3 mmol/L). Despite fluid resuscitation and administration of epinephrine (0.06 µg/kg/min), her condition failed to improve, and she was given femoral vein–femoral artery ECMO. A comprehensive search for infectious causes was undertaken. Treatment with broad-spectrum empiric antimicrobial drugs such as linezolid (Pfizer, Inc, New York, NY, USA), piperacillin/tazobactam (Wyeth, Madison, NJ, USA), and doxycycline (Pfizer, Inc) and the antiviral drug oseltamivir (Tamiflu; Roche Laboratories Inc., Nutley, NJ, USA), 150 mg 2×/d, was started. Respiratory cultures were positive for methicillin-sensitive Staphylococcus aureus and Aspergillus glaucus. Nafcillin and voriconazole were added to the treatment regimen. PCR of a bronchoalveolar lavage specimen later identified pandemic (H1N1) 2009 virus. The patient was weaned from ECMO on hospital day (HD) 10 and extubated on HD11. Repeat cardiovascular evaluation showed normal biventricular function and no coronary disease. She was discharged from hospital for rehabilitation on September 15, 2009 (HD 22), with an oxygen saturation of 98% on room air and is now fully recovered. The use of ECMO is an established option for patients with medically refractory acute and reversible cardiopulmonary failure (Table) (1–3). For isolated respiratory failure, veno–veno support can be used by femoral vein to femoral vein or femoral vein to right internal jugular vein cannulation. With concomitant cardiogenic shock, veno–arterial cannulation may be required with cannulation of the right internal jugular or femoral vein for outflow, and for inflow, the femoral artery directly or the axillary artery by a surgically placed side graft. Central venous (right atrium) and arterial (ascending aorta) cannulation is an option but requires median sternotomy. Table Relative indications and contraindications for extracorporeal membrane oxygenation* This case is not the first reported use of ECMO for respiratory failure secondary to viral pneumonia (4), and recently, ECMO was used with limited success for complications of pandemic (H1N1) 2009 (5). Its broader use in treating critically ill patients has been limited, however, because ECMO requires substantial institutional and multidisciplinary commitment for implementation and is typically only available at major medical centers offering cardiovascular surgery. Although we cannot say specifically why our patient survived, clearly, aggressive and comprehensive empiric treatment, physiologic support, and close multidisciplinary communication were vital to managing the condition of this critically ill patient. ECMO may have assisted in organ recovery and patient survival. However, further studies should be conducted to critically evaluate ECMO in the armamentarium of therapeutic options for severe pandemic (H1N1) 2009 respiratory failure.

Profound thrombocytopenia with glycoprotein IIb/IIIa inhibitors plus heparin for pump thrombus.

espite aggressive anti-coagulation, thrombotic compliations of rotary long-term ventricular assist devices emain a formidable challenge. Recently, Thomas reorted successful treatment with tirofiban, a glycoproein IIb/IIIa inhibitor. In response, we report a case of cute left ventricular assist device (LVAD) thrombosis nd a concern for glycoprotein IIb/IIIa inhibitor–inuced thrombocytopenia with worsening thrombosis. Our patient, a 61-year-old man underwent implantaion of a HeartMate II LVAD as a bridge to transplant for evere ischemic cardiomyopathy. His initial post-operaive course was uncomplicated and his anti-thrombotic egimen consisted of warfarin (4 mg/day, goal Internaional Normalized Ratio [INR] 2 to 3), aspirin (81 g/day) and persantine (75 mg three times daily). On ay 196 post-implant he was admitted with a 2-week istory of dark urine. Laboratory studies suggested VAD-induced hemolysis (Table 1). Pump flows were .0 liters/min and power was 9.0 watts (normal 7.5 atts), consistent with VAD thrombosis. He was started n eptifibatide (Integrilin; Schering-Plough), dosed at 2 g/kg/min for 84 hours, and heparin (goal activated artial thromboplastin time [aPTT] 57 to 70 seconds) rips. Within 17 hours after discontinuing the eptifiatide, severe thrombocytopenia developed (Figure 1) nd all anti-platelet agents were stopped. His pump ower remained elevated and serum creatinine inreased from 1.07 to 3.25 mg/dl. Platelet factor (PF)-4 nd aggregation assays were positive suggestive of eparin-induced thrombocytopenia (HITs). A direct hrombin inhibitor, argatroban, was started and within everal days his platelet count normalized as did renal unction, pump flows and power and lactate dehydroenase (LDH). Long-term warfarin dose was increased goal INR: 2.5 to 3.5) and clopidogrel was started (75 g/day).

Drug-Induced Exanthem following Dabigatran

Objective: To report an incident of a drug-induced exanthem during treatment with dabigatran in a patient without prior exposure to the drug. Case Summary: A 20-year-old white male was prescribed oral dabigatran 150 mg twice daily for thromboembolic prevention because of nonvalvular atrial fibrillation. After 2 weeks of dabigatran therapy, a raised, pruritic, erythematous rash developed on the patients inner thigh and forearm. Upon discontinuation of dabigatran and initiation of oral corticosteroid treatment, the rash resolved. Dabigatran therapy was not readministered and thromboembolic prevention therapy with warfarin was instituted. Discussion: The clinical evidence for efficacy of dabigatran was derived largely from the RE-LY trial, which provided an open-label comparison with warfarin for the reduction of stroke and systemic embolism in nonvalvular atrial fibrillation. The most frequent adverse reactions leading to discontinuation of dabigatran were bleeding and gastrointestinal events. In the RE-LY study, drug hypersensitivity, allergic edema, anaphylactic reaction, and anaphylactic shock were reported in <0.1% of patients receiving dabigatran. Despite the low incidence of hypersensitivity reported in the RE-LY trial, the use of the Naranjo probability scale indicated a probable relationship between the rash and dabigatran therapy in this patient. Conclusions: Upon initiation of dabigatran therapy, surveillance for hypersensitivity reactions should be included as part of routine drug monitoring.

Delayed Malignant Hyperthermia After Routine Coronary Artery Bypass

Malignant hyperthermia is a rare but well-described hypermetabolic disorder of skeletal muscle that can be potentially fatal if untreated. In our patient, malignant hyperthermia developed several minutes after discontinuation of the known triggering agent after an uncomplicated coronary revascularization. This case illustrates the dramatic presentation and successful management of a rare disease with a rare onset.

Heartmate XVE destination therapy for end-stage heart failure in a patient with human immunodeficiency virus.

Cardiac dysfunction is a known predictor of survival in patients with acquired immunodeficiency syndrome. In this report, we describe a human immunodeficiency virus (HIV)-infected patient with worsening heart failure who was managed successfully for 16 months with placement of a left ventricular assist device.

Post-infarct ventricular septal defect following thrombolytic intracranial bleed

Mechanical complications after myocardial infarction are uncommon with advances in medical reperfusion strategies. However, such strategies are associated with bleeding complications which typically contraindicate surgical management. We describe a patient with a post-infarction ventricular septal defect and an intraventricular hemorrhage following thrombolytic therapy for an acute myocardial infarction.

Bleeding outcomes associated with coronary artery bypass graft surgery and recent clopidogrel exposure.

BACKGROUND Guidelines recommend discontinuing clopidogrel for at least 5 days before elective coronary artery bypass graft surgery (CABG) to limit blood transfusions and for at least 24 hours before urgent CABG to reduce major bleeding complications. Studies have produced conflicting results regarding whether recent exposure to clopidogrel increases bleeding, the need for intraoperative and postoperative blood products, postoperative complications, and hospital length of stay. We evaluated the effect of clopidogrel exposure on major bleeding at our institution within 5 days of CABG. METHODS We conducted a retrospective review of patients who underwent CABG at a tertiary academic medical center. The primary outcome was major bleeding, defined as transfusion of 4 units of packed red blood cells (PRBCs) and/or a need for reexploration. Secondary outcomes included non-life-threatening bleeding, defined as transfusion of 2 units but <4 units of PRBCs; postoperative complications; hospital length of stay; readmission within 30 days of the procedure; and hospital mortality. Major bleeding events were analyzed with a logistic regression model that adjusted for covariates of bleeding risk factors. RESULTS Of the 715 patients we reviewed, 169 patients received clopidogrel within 5 days before CABG, and 546 patients did not. A significantly higher incidence of major bleeding was observed in the clopidogrel group compared with the group not exposed to clopidogrel (32% versus 17%, P = .002). After adjusting for covariates, patients exposed to clopidogrel had significantly higher odds of major bleeding (odds ratio, 2.1; 95% confidence interval, 1.3-3.4; P = .003). The groups were similar with respect to postoperative complications, except for infection. The clopidogrel-exposed group had a significantly higher rate of leg site infections (3% versus 0.2%, P = .003). CONCLUSIONS Clopidogrel exposure within 5 days of CABG is associated with an increased risk of major bleeding.

Development and implementation of a nurse-driven, sliding-scale nomogram for bivalirudin in the management of heparin-induced thrombocytopenia

PURPOSE A simplified dosing nomogram to assist nurses in adjusting the rate of i.v. bivalirudin administration in cases of heparin-induced thrombocytopenia (HIT) is described. SUMMARY To facilitate the availability of bivalirudin [corrected] as an alternative direct thrombin inhibitor (DTI) for patients with HIT at The Ohio State University Wexner Medical Center (OSUWMC), a team of clinical pharmacists developed a nomogram designed to simplify infusion dosage adjustments by nurses. In contrast to bivalirudin nomograms requiring patient-specific, percentage-based dose adjustments, the nomogram developed at OSUWMC specifies fixed adjustments (0.005 or 0.01 mg/kg/hr) according to the current activated partial thromboplastin time (aPTT) value relative to aPTT goals. During pilot testing over three years, the nomogram was used to guide dosage adjustments in 65 adult patients receiving continuous infusions of bivalirudin for suspected or confirmed HIT in intensive care units. Overall, the use of the nomogram resulted in adequate anticoagulation, with 53.7% of all measured aPTT values in the target range; 30.5% of aPTT values were below target, and 15.8% of values were above target. The median time to steady state was 11.0 hours (range, 5.0-31.8 hours), and bleeding rates were consistent with those reported in the literature. Nurse adherence to the nomogram was 100%, and no dosing errors occurred during a total of 487 dosage changes. Based on the pilot study results, the nomogram was refined to improve initial dosing for patients with creatinine clearance values of >30 mL/min; other refinements were made to enhance the safety of bivalirudin therapy for HIT in patients with severe renal impairment. CONCLUSION A nurse-driven, sliding-scale nomogram for bivalirudin therapy in patients with HIT provided a simple dosing protocol and resulted in a high rate of adherence by nurses.

Superior vena cava bypass with cryopreserved ascending aorta allograft.

Initially superior vena cava obstruction is typically managed by an endovascular approach. However, in some patients, particularly those in whom angioplasty and stenting is not technically possible, or those who have recurrent disease after previous endovascular repair, an open surgical approach may be indicated. Conduit choices for caval reconstruction are less than ideal; hence we describe a case using a cryopreserved aortic allograft.