K. Muthiah

Thrombolysis for Suspected Intrapump Thrombosis in Patients With Continuous Flow Centrifugal Left Ventricular Assist Device

The current recommended anticoagulation regimen during continuous flow centrifugal left ventricular device support is a combination of antiplatelet therapy as well as oral anticoagulation. Despite this, pump thrombosis occurs in rare situations. We report the risk factors and nonsurgical management and outcomes of five patients implanted with continuous flow centrifugal left ventricular assist devices who displayed clinical, hemodynamic, and laboratory features of intrapump thrombosis. This information may support the use of intravenous thrombolytics for suspected pump thrombus in these newer generation devices.

Body position and activity, but not heart rate, affect pump flows in patients with continuous-flow left ventricular assist devices.

OBJECTIVES The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs). BACKGROUND Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return. METHODS Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded. RESULTS Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p < 0.0001 analysis of variance). With active ankle flexion, LVAD flow returned to baseline. There was no significant change in flow with a 20° head-down tilt with or without ankle flexion exercise. There were no suction events. CONCLUSIONS Centrifugal cfLVAD flows are not significantly affected by changes in heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate.

Longitudinal changes in hemostatic parameters and reduced pulsatility contribute to non-surgical bleeding in patients with centrifugal continuous-flow left ventricular assist devices.

BACKGROUND Bleeding and thromboembolic events are identified complications in patients supported with newer centrifugal continuous-flow left ventricular assist devices (cfLVADs). Bleeding events have been associated with acquired von Willebrand syndrome (vWS) in these patients, though longitudinal changes and the effect of pulsatility remain unquantified. We evaluated longitudinal effects of third-generation cfLVADs on hemostatic biomarkers, non-surgical bleeding, and thromboembolic events. We investigated the association between pulsatility (as defined by aortic valve opening) on von Willebrand Factor (VWF) profile and bleeding. METHODS We prospectively studied 28 patients implanted with the HeartWare (HeartWare International, Framingham, MA) cfLVAD for up to 360 days. We performed bleeding and coagulation assays 8 times from pre-implant to Day 360 (D360) post-implant, including platelet aggregometry, VWF collagen binding activity-to-antigen (CBA/Ag) ratio, thromboelastography, soluble P-selectin, platelet-specific marker soluble glycoprotein VI (sGPVI), and platelet microparticles. Aortic valve opening was assessed by echocardiography at each assessment. Bleeding and thromboembolic events were documented. RESULTS Bleeding events occurred in 14 patients (50%). Maximal platelet inhibition occurred by D30. VWF profile impairment (VWF CBA/Ag < 0.8) was demonstrated in 89% of patients at D30, with subsequent recovery but further deterioration after D180. Bleeding was associated with elevated pre-implant sGPVI (p = 0.008). Pulsatility was associated with higher VWF CBA/Ag (p = 0.02) and a trend to less bleeding. CONCLUSIONS Third-generation cfLVADs were associated with longitudinal changes in hemostatic markers, and bleeding was associated with elevated pre-implant plasma sGPVI. Further, pulsatility may contribute to recovery of the VWF profile and potentially lower bleeding risk.

Centrifugal continuous-flow left ventricular assist device in patients with hypertrophic cardiomyopathy: a case series.

Left ventricular assist device (LVAD) therapy has been used primarily in patients with end-stage dilated cardiomyopathy (DCM), and patients with hypertrophic cardiomyopathy (HCM) are generally excluded. We compared outcomes in 3 HCM patients with 36 DCM patients. While HCM patients had smaller left ventricular end-diastolic dimensions, average pump flows for the two groups were similar. All patients had marked improvement in mean pulmonary arterial pressures and cardiac index at 5 months. This analysis shows that patients with end-stage heart failure resulting from HCM do benefit from centrifugal cfLVAD therapy in the short to medium term.

Normalisation of Haemodynamics in Patients with End-stage Heart Failure with Continuous-flow Left Ventricular Assist Device Therapy

BACKGROUND New generation continuous-flow left ventricular assist devices (LVADs) utilise centrifugal pumps. Data concerning their effect on patient haemodynamics, ventricular function and tissue perfusion is limited. We aimed to document these parameters following HeartWare centrifugal continuous-flow LVAD (HVAD) implantation and to assess the impact of post-operative right heart failure (RHF). METHODS We reviewed 53 consecutive patients (mean age 49.5 ± 14.1 yrs) with HVAD implanted in the left ventricle, at St. Vincents Hospital, Sydney, between January 2007 and August 2012. Available paired right heart catheterisation (n=35) and echocardiography (n=39) data was reviewed to assess response of invasive haemodynamics and ventricular function to LVAD support. RESULTS A total of 28 patients (53%) were implanted from interim mechanical circulatory support. Seventeen patients (32%) required short-term post-implant veno-pulmonary artery extracorporeal membrane oxygenation. At 100 ± 61 days post-implant, mean pulmonary artery pressure and mean pulmonary capillary wedge pressure decreased from 38.8 ± 7.7 to 22.9 ± 7.7 mmHg and 28.3 ± 6.4 to 13.4 ± 5.4 mmHg respectively (p<0.001). LV end diastolic diameter decreased from 71.3 ± 12.7 to 61.1 ± 13.7 mm and LV end-systolic diameter from 62.7 ± 12.3 to 53.9 ± 14.4mm (p<0.001). Aortic regurgitation remained trivial. Serum sodium increased from 133.3 ± 5.7 to 139.3 ± 2.8 mmol/L and creatinine decreased from 109.1 ± 42.5 to 74.3 ± 26.2 μmol/L (p<0.001). Across the entire cohort, the six-month survival/transplant rate was significantly lower for RHF patients (72.2%, n=18) compared to those without (96.9%, n=35, p=0.01). CONCLUSIONS HVAD support improves haemodynamics, LV dimensions and renal function. Following implantation with a centrifugal continuous-flow LVAD, RHF remains a significant risk with a tendency to worse outcomes in the short to medium term.

Impact of Implantable Cardioverter Defibrillators on Survival of Patients with Centrifugal Left Ventricular Assist Devices

Both implantable cardioverter defibrillators (ICDs) and left ventricular assist devices (LVADs) have a positive impact on survival in the heart failure population. We sought to determine whether these positive effects on survival are additive or whether LVAD therapy supersedes ICD therapy.

Increased incidence of angiodysplasia of the gastrointestinal tract and bleeding in patients with continuous flow left ventricular assist devices (LVADs)

Background Continuous flow left ventricular assist devices (cfLVADs) are used in clinical practice for the management of end-stage heart failure. Axial flow cfLVADS have been associated with increased rates of adverse gastrointestinal events such as bleeding angiodysplasia. The purpose of this study was to determine the incidence of bleeding gastrointestinal tract angiodysplasia and the profile of patients supported with the centrifugal cfLVAD, referred for endoscopy. Methods A retrospective analysis of 66 patients implanted with Ventrassist (n = 33) and Heartware (n = 33) centrifugal continuous flow LVADs was performed. All patients were on warfarin, aspirin and/or clopidogrel. Endoscopy was performed in all patients with either active gastrointestinal bleeding (n = 6) or anemia with positive fecal occult blood (n = 6). Results Bleeding gastrointestinal angiodysplasia was demonstrated in 5 out of the 12 (41.6%) patients who underwent endoscopy from the cohort of 66 cfLVAD supported patients (7.6%). The incidence of bleeding angiodysplasia was higher than the age-standardized rate of andiodysplasia from literature (0.8%). Active gastrointestinal bleeding in one other patient was due to diverticulosis. The five patients with bleeding angiodysplasia tended to be older than the remaining 61 patients (58.8 ± 10.3 vs 49.6 ± 15.7 years, p = 0.2). Conclusions We found excess bleeding angiodysplasia in patients on centrifugal cfLVAD support. It may be appropriate to screen for angiodysplasia particularly in older patients prior to support by centrifugal cf LVADs. Reasons for the higher rate of bleeding angiodysplasia in cfLVAD patients warrant further study.

Imatinib for the treatment of pulmonary arterial hypertension and pulmonary capillary hemangiomatosis.

Despite currently available treatments, the prognoses of pulmonary arterial hypertension (PAH) and pulmonary capillary hemangiomatosis (PCH) remain poor. Platelet-derived growth factor and its receptor (PDGFR) have been implicated in the pathogenesis of pulmonary hypertension in PAH and PCH. Imatinib, a PDGFR antagonist, may be beneficial in the treatment of both conditions because of its potent antiproliferative effect. We report two cases that demonstrate the potential for safe and efficacious use of imatinib in PAH and PCH.

Longitudinal structural, functional, and cellular myocardial alterations with chronic centrifugal continuous-flow left ventricular assist device support

BACKGROUND Left ventricular assist device (LVAD) support triggers adaptations within failing hearts. The HeartWare (HeartWare International, Inc., Framingham, MA) LVAD exhibits different flow profiles and afterload dependence compared with previous-generation devices, which may alter remodelling patterns. We sought to characterize myocardial adaptation to third-generation centrifugal-flow LVADs at a functional, hemodynamic, and structural level in addition to profiling transcriptomal changes using next-generation sequencing platforms. METHODS We studied 37 patients supported with the HeartWare device with paired measurements of invasive hemodynamics, serial longitudinal left ventricular (LV) and right ventricular (RV) 3-dimensional echocardiography, and N-terminal of the prohormone brain natriuretic peptide (NT-proBNP) measurements. Paired samples for comparison of histologic myocardial cellular size and transcriptomal profiling were performed on specimens taken at pump implant and transplantation. RESULTS The mean support duration was 280 ± 163 days. Mechanical unloading after HeartWare support resulted in reduced filling pressures (mean pulmonary capillary wedge pressure 27.1 ± 6.6 to 14.8 ± 5.1 mm Hg, p < 0.0001). Mean LV cardiomyocyte cell size decreased from 2,789.7 ± 671.8 to 2,290.8 ± 494.2 μm2 (p = 0.02). LV and RV ejection fractions improved significantly (24% ± 8% to 35% ± 9% [p < 0.001] and 35% ± 11% to 40% ± 8% [p < 0.02], respectively). NT-proBNP levels fell 4.8-fold by Day 90 after support, consistent with a decrease in LV wall stress. Despite these concordant beneficial findings, the microRNA transcriptome did not change significantly across the group. CONCLUSIONS Reverse remodelling is evident at multiple levels with chronic HeartWare support in the absence of changes in the microRNA transcriptome. Successful myocardial unloading is associated with a decrease in wall stress, regression of cardiomyocyte hypertrophy, and an improvement in LV and RV ejection fractions.

Pulmonary Tumor Thrombotic Microangiopathy from Metastatic Prostate Carcinoma

Pulmonary tumor thrombotic microangiopathy is a rare but serious malignancy-related respiratory complication. The most common causative neoplasm is gastric adenocarcinoma. We report a case caused by metastatic prostate adenocarcinoma, diagnosed postmortem in a 58-year-old male. To our knowledge, this is the second reported case from metastatic prostate adenocarcinoma.