Coagulopathy in Mechanical Circulatory Support: A Fine Balance

Urgent Spinal Surgery in a Lateral Decubitus on a Patient with a Left Ventricular Assist Device on Full Anticoagulation: A Case Report

This case report aims to demonstrate the feasibility of performing spinal surgery in patients with a left ventricular assist device (LVAD), who are traditionally considered unsuitable candidates due to the need for anticoagulation and the challenges associated with the prone position. A case of a patient with an LVAD undergoing microdiscectomy in the left lateral decubitus position is presented. The procedure was carried out by a specialized interdisciplinary team with appropriate monitoring. The patient underwent the procedure safely, demonstrating that spinal surgery can be performed in patients with LVAD without reversing anticoagulation or resorting to the prone position. This approach mitigates the risk of thrombotic events and hemodynamic instability. This case study suggests that spinal surgery, specifically microdiscectomy, can be safely performed in patients with LVAD using the left lateral decubitus position. This finding has significant implications for patients who are unable to ambulate and therefore struggle to qualify for a heart transplant.

How well do we understand pulsatility in the context of modern ventricular assist devices?

BACKGROUND

Modern ventricular assist devices (VADs) use a continuous flow design. It has been suggested that a lack of pulsatility contributes to a range of adverse outcomes including pump thrombus, gastrointestinal bleeding and stroke. To better assess the role of pulsatility in these adverse events, we first require a clear definition of 'pulsatility' in the setting of a severely impaired ventricle and a modern continuous flow VAD.

METHODS

A literature review was conducted to elucidate the understanding of pulsatility in modern VAD literature. Search engines used included PUBMED, EMBASE and the Cochrane library. Articles were appraised on three aspects: Whether they mentioned pulsatility; whether they mentioned which pulsatility measure was used and finally which methodology was used to obtain the value.

RESULTS

Of 354 articles reviewed, only 13 met our broad inclusion criteria. Of these articles, the most cited measure was pulsatility index (PI) - used by 11 of the publications. The methodology used to obtain the value was not uniform and five articles did not clearly state it. Other measures included pulse pressure and surplus haemodynamic energy. The majority of articles did not directly discuss pulsatility in the setting of patient-pump interaction.

CONCLUSION

Most publications did not provide a definition for pulsatility. In those that did, the most common measure was PI. Measuring PI was not standardised. Few papers addressed the impact of intrinsic ventricular function and arterial compliance on pulsatility. We suggest that future publications adopt a uniform definition which encompasses both patient and pump characteristics.

The Use of Factor Eight Inhibitor Bypass Activity (FEIBA) for the Treatment of Perioperative Hemorrhage in Left Ventricular Assist Device Implantation

OBJECTIVE

To test the hypothesis that factor eight inhibitor bypassing activity (FEIBA) can be used to control bleeding following left ventricular assist device (LVAD) implantation without increasing the 14-day composite thrombotic outcome of pump thrombus, ischemic cerebrovascular accidents, pulmonary embolism, and deep venous thrombosis.

DESIGN

Retrospective cohort study.

SETTING

Academic hospital.

PARTICIPANTS

Three hundred nineteen consecutive patients who underwent LVAD implantation (December 1, 2009 to December 30, 2018).

INTERVENTION

FEIBA administered to control perioperative hemorrhage.

MEASUREMENTS AND MAIN RESULTS

The 82 patients (25.7%) in the FEIBA cohort had more risk factors for perioperative hemorrhage, such as lower preoperative platelet count (169 ± 66 v 194 ± 68 × 10³/mL, p = 0.004), prior cardiac surgery (36.6% v 21.9%, p = 0.008), and longer cardiopulmonary bypass (CPB) time (100.3 v 75.2 minutes, p = 0.001) than the 237 controls. After 16.6 units (95% CI: 14.3-18.9) of blood products were given, 992 units (95% CI: 821-1163) of FEIBA were required to control bleeding in the FEIBA cohort. Compared to the controls, there were no differences in the 14-day composite thrombotic outcome (11.0% v 7.6%, p = 0.343) or mortality rate (3.7% v 1.3%, p = 0.179). Multivariate logistical regression identified preoperative international normalized ratio (odds ratio [OR]: 1.30, 95% CI: 1.04-1.62) and CPB time (OR: 1.11, 95% CI: 1.02-1.20) as risk factors for 14-day thrombotic events, but FEIBA usage was not associated with an increased risk.

CONCLUSIONS

In this retrospective cohort study, the use of FEIBA (∼1,000 units, ∼13 units/kg) to control perioperative hemorrhage following LVAD implantation was not associated with increases in mortality or composite thrombotic outcome.

Risk of Thrombus Formation in Patients on Mechanical Circulatory Support with POLVAD-MEV

BACKGROUND Congestive heart failure is a challenging problem due to increasing prevalence in developed countries. Patients admitted due to decompensated congestive heart failure symptoms who do not respond to medical treatment require mechanical circulatory support. Patients with biventricular failure are at particularly high mortality risk. MATERIAL AND METHODS We analyzed the function of 49 pumps (POLVAD-MEV, FRK Intra-cordis, Poland) implanted to rescue INTERMACS 1 and 2 profile patients referred to our department due to severe congestive heart failure. All patients were waiting for heart transplantation and were readmitted due to acute decompensations of congestive biventricular heart failure with resistance to medical therapy. RESULTS During the observational period, there were no technical problems in pump function. The mean duration of pump therapy was 30.6±8.3 (5-49) days. The risk for right-sided pump complications included clots formation on the following parts of the pump: outflow tract (1, 2%), membrane (13, 27%), dome (6, 12.5%), and periphery (1, 2%). The overall risk for device thrombosis was 41%. The risk for thromboembolic complications was CRP-dependent regarding conglomerates of fibrin and platelets formation (p<0.05). The risk for left-sided pump complications included clots formation on the outflow tract (1, 2%), membrane (9, 19%) and dome (3, 6%). The overall risk for device thrombosis was 27%. The risk for clots formation on the membrane (P<0.05) and dome of the pump depended on time (P<0.07). CONCLUSIONS Mechanical circulatory support with a paracorporeal pump is a safe option for biventricular heart dysfunction as a bridge to heart transplantation. The risk for thrombi formation is relatively high but acceptable within 30 days after implantation.

Postimplant Phosphodiesterase Type 5 Inhibitors Use Is Associated With Lower Rates of Thrombotic Events After Left Ventricular Assist Device Implantation

Background Left ventricular assist device (LVAD) thrombosis is clinically devastating and impacts the cost effectiveness of LVAD therapy for advanced heart failure. Anticoagulation and antiplatelet therapies represent the standard of care to mitigate LVAD thrombosis. Phosphodiesterase type 5 inhibitors (PDE-5is) exhibit hemodynamic, antiplatelet, and antithrombotic effects. Using a national registry, we examined the relationship of PDE-5i use on thrombotic events in patients with continuous-flow LVADs. Methods and Results We obtained data from 13 772 patients with continuous flow LVADs participating in a national registry. Patients implanted with primary LVADs from 2012 to 2017 were included in the analysis. The primary end point was a composite of LVAD thrombosis and ischemic stroke. Patients were analyzed according to any use of PDE-5i after LVAD implantation (PDE-5i group) versus no use after LVAD implantation (no PDE-5i group). The primary end point was significantly lower in the PDE-5i group compared with the no PDE-5i group (hazard ratio [HR], 0.84; 95% CI, 0.77-0.91; P<0.001) at 48 months. The components of the primary end point (LVAD thrombosis: HR, 0.82; 95% CI, 0.74-0.90; P<0.001; and ischemic stroke: HR, 0.85; 95% CI, 0.75-0.97; P=0.019), as well as the secondary end point all-cause mortality (HR, 0.86; 95% CI, 0.79-0.93; P<0.001) were lower in the PDE-5i group versus the no PDE-5i at 48 months post LVAD. The favorable results observed with postimplant PDE-5i use were consistent with both axial and centrifugal flow devices. Conclusions The postimplant use of PDE-5i was associated with fewer thrombotic events and improved survival in LVAD patients. A randomized clinical trial is warranted to confirm these findings.

The association between novel clinical factors and gastrointestinal bleeding among patients supported with continuous-flow left ventricular assist device therapy

BACKGROUND

This study explores novel preimplantation risk factors associated with gastrointestinal bleeding (GIB) after continuous-flow left ventricular assist device (CF-LVAD) implantation. CF-LVAD therapy implantation for patients with advanced heart failure is associated with a 20% to 40% incidence of GIB.

METHODS

This study includes patients receiving CF-LVAD at a quaternary medical center from 2006 to 2014 (n = 254). The primary endpoint was GIB within 12 months after implantation; the secondary outcome was 3-year all-cause mortality. The Student t test or the χ² test compared continuous or categorical variables. Competing risks analysis calculated the cumulative incidence of GIB postimplantation. Cox proportional hazards model was used for univariate/multivariate models predicting GIB.

RESULTS

Sixty-four patients had GIB, with incidence rates at 1, 3, and 12 months of 11.8%, 19.3%, and 25.2%, respectively. Endoscopy revealed no identified source of bleeding in 41%; 33% of lesions were localized in the upper gastrointestinal tract, with the bulk (39%) categorized as vascular. Patients with prior gastrointestinal abnormalities (n = 98) had a greater risk of GIB post-CF-LVAD (HR 1.85 [1.11-3.09]; P = 0.02) than those with normal gastrointestinal evaluation results (n = 45) and those without preimplantation gastrointestinal evaluation (n = 111). Baseline blood urea nitrogen, chronic obstructive pulmonary disease, and prior percutaneous coronary intervention were statistically associated with post-CF-LVAD GIB. The presence of GIB within 12 months of CF-LVAD implantation was associated with an increased risk of 3-year all-cause mortality (HR 2.57 [1.57-4.15]; P < 0.01).

CONCLUSIONS

First-year GIB is associated with increased mortality post-CF-LVAD. We advocate a closer examination of several GIB risk factors when evaluating CF-LVAD candidates.

Sex-Specific Outcome Disparities in Patients Receiving Continuous-Flow Left Ventricular Assist Devices: A Systematic Review and Meta-analysis

Continuous-flow left ventricular assist devices (CF-LVADs) decrease mortality and improve quality of life in patients with advanced heart failure (HF). Their widespread utilization has led to concerns regarding increased adverse effects, especially in women. Nevertheless, sex-specific data remain limited. We searched Medline, Embase, Scopus, and the Cochrane Library for publications reporting sex-specific outcomes after CF-LVADs from January 2008 through January 2017. Outcomes were compared under the random-effects model and heterogeneity examined via χ test and I statistics. A total of 10 studies including 4,493 CF-LVAD recipients were included in the analysis (23.5% women). The overall rate of stroke was significantly higher in women (odds ratio [OR] 1.94; 95% confidence interval [CI] 1.32-2.84; p = 0.0007). This was true for ischemic strokes (OR 2.03; 95% CI 1.21-3.42; p = 0.008) and hemorrhagic strokes (OR 2.03; 95% CI 1.21-3.42; p = 0.008). Women were also more likely to develop right HF necessitating right ventricular assist device (RVAD) implantation (OR 2.12; 95% CI 1.08-4.15; p = 0.03). Other adverse events including renal failure, bleeding, and device-related infection were comparable for both genders. The overall mortality while on CF-LVAD was similar in both groups (OR 1.05; 95% CI 0.81-1.36; p = 0.71). Our analysis suggests that women are at greater risk of significant complications such as cerebrovascular events and right HF necessitating RVAD after CF-LVAD implantation. Further research is needed to better understand the mechanisms underlying these sex-specific outcome disparities.

Monitoring hemostasis parameters in left ventricular assist device recipients - a preliminary report

Introduction

Mechanical circulatory support (MCS) therapy is associated with the improvement of long-term prognosis in patients with end-stage heart failure. For years it has been used as a bridge to transplant. However, more recently it is even being used as a destination therapy. Recently, clinicians have identified common MCS therapy-associated complications: pump thrombosis, bleeding, and hemolysis. These complications are very challenging with regard to both diagnosis and management.

Aim

To determine time-dependant changes of selected hemostasis/coagulation parameters in patients with end-stage heart failure treated with MCS and antithrombotic therapy.

Material and methods

Sixteen patients with end-stage heart failure on left ventricular assist device (LVAD) were followed for 6 weeks (six blood samples for each patient). Every week an extended hemostasis panel was assessed, including activated partial thromboplastin time, prothrombin time, international normalized ratio, von Willebrand factor (vWF) activity, factor VIII activity, fibrinogen level, D-dimer, platelet response to arachidonic acid (ASPI test) and adenosine diphosphate (ADP test), thrombin receptor activating peptide-6 (TRAP test) and collagen (COL test).

Results

The study population comprised 16 men. The median time from LVAD implantation was 120 days (100–150 days). During the study period the D-dimer and fibrinogen concentrations were elevated but remained similar throughout all six measurements. Meanwhile factor VIII and vWF activities were elevated in the first two measurements and then subsequently declined. Inhibition of platelet aggregation was greater early after LVAD implantation. During subsequent weeks the inhibition of platelet aggregation was less pronounced. No patient developed any bleeding or thrombo-embolic event during the study period.

Conclusions

Patients on MCS therapy demonstrate significant time-dependant changes in hemostasis parameters (both in the coagulation system and platelet aggregation).

Mechanical blood trauma in assisted circulation: sublethal RBC damage preceding hemolysis

After many decades of improvements in mechanical circulatory assist devices (CADs), blood damage remains a serious problem during support contributing to variety of adverse events, and consequently affecting patient survival and quality of life. The mechanisms of cumulative cell damage in continuous-flow blood pumps are still not fully understood despite numerous in vitro, in vivo, and in silico studies of blood trauma. Previous investigations have almost exclusively focused on lethal blood damage, namely hemolysis, which is typically negligible during normal operation of current generation CADs. The measurement of plasma free hemoglobin (plfHb) concentration to characterize hemolysis is straightforward, however sublethal trauma is more difficult to detect and quantify since no simple direct test exists. Similarly, while multiple studies have focused on thrombosis within blood pumps and accessories, sublethal blood trauma and its sequelae have yet to be adequately documented or characterized. This review summarizes the current understanding of sublethal trauma to red blood cells (RBCs) produced by exposure of blood to flow parameters and conditions similar to those within CADs. It also suggests potential strategies to reduce and/or prevent RBC sublethal damage in a clinically-relevant context, and encourages new research into this relatively uncharted territory.