[Technical possibilities and limitations of mechanical circulatory support]

Management of Complications in Long-Term LVAD Support

Introduction

Management of complications in long-term LVAD support like aortic regurgitation, progressive decline of right ventricular function, or pump thrombosis are challenging.

Methods and Results

After 2.5 years on a HeartMate II left ventricular assist device (LVAD) a 59-year-old patient was admitted to hospital due to severe hemolysis caused by a partial occlusion and thrombosis caused by a shift of the LVAD inflow cannula towards the lateral wall of the left ventricle (LV). Preoperative assessment revealed additional severe aortic regurgitation and impaired right ventricular (RV) function (severe tricuspid regurgitation, RV ejection fraction 25%, central venous pressure 14 mmHg). After LVAD device exchange and aortic valve replacement (AVR) RV failure occurred and a temporary right ventricular assist device (RVAD) was employed. RVAD explantation was feasible 21 days after surgery. The patient was discharged to a rehabilitation center.

Discussion

In this case, LVAD exchange with concomitant AVR and temporary RVAD efforts saved the patient's life and restored a good quality of life.

Coagulation management in patients undergoing mechanical circulatory support

The incidence of bleeding and thrombo-embolic complications in patients undergoing mechanical circulatory support therapy remains high and is associated with bad outcomes and increased costs. The need for anticoagulation and anti-platelet therapy varies widely between different pulsatile and non-pulsatile ventricular-assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) systems. Therefore, a unique anticoagulation protocol cannot be recommended. Notably, most thrombo-embolic complications occur despite values of conventional coagulation tests being within the targeted range. This is due to the fact that conventional coagulation tests such as international normalised ratio (INR), activated partial thromboplastin time (aPTT) and platelet count cannot detect hyper- or hypofibrinolysis, hypercoagulability due to tissue factor expression on circulating cells or increased clot firmness, and platelet aggregation as well as response to anti-platelet drugs. By contrast, point-of-care (POC) whole blood viscoelastic tests (thromboelastometry/-graphy) and platelet function tests (impedance or turbidimetric aggregometry) reflect in detail the haemostatic status of patients undergoing mechanical circulatory support therapy and the efficacy of their anticoagulation and antiaggregation therapy. Therefore, monitoring of haemostasis using POC thromboelastometry/-graphy and platelet function analysis is recommended during mechanical circulatory support therapy to reduce the risk of bleeding and thrombo-embolic complications. Notably, these haemostatic tests should be performed repeatedly during mechanical circulatory support therapy since thrombin generation, clot firmness and platelet response may change significantly over time with a high inter- and intra-individual variability. Furthermore, coagulation management can be hampered in non-pulsatile VADs by acquired von Willebrand syndrome, and in general by acquired factor XIII deficiency as well as by heparin-induced thrombocytopenia. In addition, POC testing can be used in bleeding patients to guide calculated goal-directed therapy with allogeneic blood products, haemostatic drugs and coagulation factor concentrates to optimise the haemostasis and to minimise transfusion requirements, transfusion-associated adverse events and to avoid thrombo-embolic complications, as well. However, coagulation management in patients undergoing mechanical circulatory support therapy is somehow like navigating between Scylla and Charybdis, and development of protocols based on POC testing seems to be beneficial.