Emily Granger

Extracorporeal Membrane Oxygenation for 2009 Influenza A(H1N1) Acute Respiratory Distress Syndrome.

CONTEXT The novel influenza A(H1N1) pandemic affected Australia and New Zealand during the 2009 southern hemisphere winter. It caused an epidemic of critical illness and some patients developed severe acute respiratory distress syndrome (ARDS) and were treated with extracorporeal membrane oxygenation (ECMO). OBJECTIVES To describe the characteristics of all patients with 2009 influenza A(H1N1)-associated ARDS treated with ECMO and to report incidence, resource utilization, and patient outcomes. DESIGN, SETTING, AND PATIENTS An observational study of all patients (n = 68) with 2009 influenza A(H1N1)-associated ARDS treated with ECMO in 15 intensive care units (ICUs) in Australia and New Zealand between June 1 and August 31, 2009. MAIN OUTCOME MEASURES Incidence, clinical features, degree of pulmonary dysfunction, technical characteristics, duration of ECMO, complications, and survival. RESULTS Sixty-eight patients with severe influenza-associated ARDS were treated with ECMO, of whom 61 had either confirmed 2009 influenza A(H1N1) (n = 53) or influenza A not subtyped (n = 8), representing an incidence rate of 2.6 ECMO cases per million population. An additional 133 patients with influenza A received mechanical ventilation but no ECMO in the same ICUs. The 68 patients who received ECMO had a median (interquartile range [IQR]) age of 34.4 (26.6-43.1) years and 34 patients (50%) were men. Before ECMO, patients had severe respiratory failure despite advanced mechanical ventilatory support with a median (IQR) Pao(2)/fraction of inspired oxygen (Fio(2)) ratio of 56 (48-63), positive end-expiratory pressure of 18 (15-20) cm H(2)O, and an acute lung injury score of 3.8 (3.5-4.0). The median (IQR) duration of ECMO support was 10 (7-15) days. At the time of reporting, 48 of the 68 patients (71%; 95% confidence interval [CI], 60%-82%) had survived to ICU discharge, of whom 32 had survived to hospital discharge and 16 remained as hospital inpatients. Fourteen patients (21%; 95% CI, 11%-30%) had died and 6 remained in the ICU, 2 of whom were still receiving ECMO. CONCLUSIONS During June to August 2009 in Australia and New Zealand, the ICUs at regional referral centers provided mechanical ventilation for many patients with 2009 influenza A(H1N1)-associated respiratory failure, one-third of whom received ECMO. These ECMO-treated patients were often young adults with severe hypoxemia and had a 21% mortality rate at the end of the study period.

Adult heart transplantation with distant procurement and ex-vivo preservation of donor hearts after circulatory death: a case series

BACKGROUND Orthotopic heart transplantation is the gold-standard long-term treatment for medically refractive end-stage heart failure. However, suitable cardiac donors are scarce. Although donation after circulatory death has been used for kidney, liver, and lung transplantation, it is not used for heart transplantation. We report a case series of heart transplantations from donors after circulatory death. METHODS The recipients were patients at St Vincents Hospital, Sydney, Australia. They received Maastricht category III controlled hearts donated after circulatory death from people younger than 40 years and with a maximum warm ischaemic time of 30 min. We retrieved four hearts through initial myocardial protection with supplemented cardioplegia and transferred to an Organ Care System (Transmedics) for preservation, resuscitation, and transportation to the recipient hospital. FINDINGS Three recipients (two men, one woman; mean age 52 years) with low transpulmonary gradients (<8 mm Hg) and without previous cardiac surgery received the transplants. Donor heart warm ischaemic times were 28 min, 25 min, and 22 min, with ex-vivo Organ Care System perfusion times of 257 min, 260 min, and 245 min. Arteriovenous lactate values at the start of perfusion were 8·3-8·1 mmol/L for patient 1, 6·79-6·48 mmol/L for patient 2, and 7·6-7·4 mmol/L for patient 3. End of perfusion lactate values were 3·6-3·6 mmol/L, 2·8-2·3 mmol/L, and 2·69-2·54 mmol/L, respectively, showing favourable lactate uptake. Two patients needed temporary mechanical support. All three recipients had normal cardiac function within a week of transplantation and are making a good recovery at 176, 91, and 77 days after transplantation. INTERPRETATION Strict limitations on donor eligibility, optimised myocardial protection, and use of a portable ex-vivo organ perfusion platform can enable successful, distantly procured orthotopic transplantation of hearts donated after circulatory death. FUNDING NHMRC, John T Reid Charitable Trust, EVOS Trust Fund, Harry Windsor Trust Fund.

Primary Graft Failure after Heart Transplantation

Primary graft failure (PGF) is a devastating complication that occurs in the immediate postoperative period following heart transplantation. It manifests as severe ventricular dysfunction of the donor graft and carries significant mortality and morbidity. In the last decade, advances in pharmacological treatment and mechanical circulatory support have improved the outlook for heart transplant recipients who develop this complication. Despite these advances in treatment, PGF is still the leading cause of death in the first 30 days after transplantation. In todays climate of significant organ shortages and growing waiting lists, transplant units worldwide have increasingly utilised “marginal donors” to try and bridge the gap between “supply and demand.” One of the costs of this strategy has been an increased incidence of PGF. As the threat of PGF increases, the challenges of predicting and preventing its occurrence, as well as the identification of more effective treatment modalities, are vital areas of active research and development.

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.

Long-term biventricular HeartWare ventricular assist device support—Case series of right atrial and right ventricular implantation outcomes

BACKGROUND There is limited information on outcomes using the HeartWare ventricular assist device (HVAD; HeartWare, Framington, MA) as a biventricular assist device, especially with respect to site of right ventricular assist device (RVAD) implantation. METHODS Outcomes in 13 patients with dilated cardiomyopathy and severe biventricular failure who underwent dual HVAD implantation as bridge to transplantation between August 2011 and October 2014 were reviewed. RESULTS Of 13 patients, 10 were Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) Level 1, and 3 were INTERMACS Level 2. Mean age was 45 ± 11 years, and mean body mass index was 26 ± 4 kg/m(2). There were 7 patients on temporary mechanical support pre-operatively (extracorporeal life support, n = 5; intra-aortic balloon pump, n = 2). The median hospital length of stay was 53 days (interquartile range [IQR] 33-70 days) with a median intensive care unit length of stay of 14 days (IQR 8-36 days). The median length of support on device was 269 days (IQR 93-426 days). The right HVAD was implanted in the right ventricular (RV) free wall in 6 patients and in the right atrial (RA) free wall in 7 patients. Transplantation was successfully performed in 5 patients, and overall survival for the entire cohort was 54%. RVAD pump thrombosis occurred in 3 of 6 RV pumps and 1 of 7 RA pumps. No left ventricular assist device pump thrombosis was observed. Bleeding tended to be higher in the RV implantation group (3 of 6 vs 0 of 7). During follow up, 6 patients died (4 of 7 in the RA group vs 2 of 6 in the RV group). Cause of death was multiple-organ failure in 3 patients, sepsis in 2 patients, and intracerebral hemorrhage in 1 patient. CONCLUSIONS Critically ill patients who require biventricular support can be successfully bridged to transplant using 2 HVADs. RA implantation may allow right heart support with lower pump thrombosis and bleeding complications, although this was at the expense of a higher mortality in this cohort.

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.

Extracorporeal cardiopulmonary resuscitation for refractory cardiac arrest: A multicentre experience.

AIM To describe the ECPR experience of two Australian ECMO centres, with regards to survival and neurological outcome, their predictors and complications. METHODS Retrospective observational study of prospectively collected data on all patients who underwent extracorporeal cardiopulmonary resuscitation (ECPR) at two academic ECMO referral centres in Sydney, Australia. MEASUREMENTS AND MAIN RESULTS Thirty-seven patients underwent ECPR, 25 (68%) were for in-hospital cardiac arrests. Median age was 54 (IQR 47-58), 27 (73%) were male. Initial rhythm was ventricular fibrillation or pulseless ventricular tachycardia in 20 patients (54%), pulseless electrical activity (n=14, 38%), and asystole (n=3, 8%). 27 (73%) arrests were witnessed and 30 (81%) patients received bystander CPR. Median time from arrest to initiation of ECMO flow was 45min (IQR 30-70), and the median time on ECMO was 3days (IQR 1-6). Angiography was performed in 54% of patients, and 27% required subsequent coronary intervention (stenting or balloon angioplasty 24%). A total of 13 patients (35%) survived to hospital discharge (IHCA 33% vs. OHCA 37%). All survivors were discharged with favourable neurological outcome (Cerebral Performance Category 1 or 2). Pre-ECMO lactate level was predictive of mortality OR 1.35 (1.06-1.73, p=0.016). CONCLUSIONS In selected patients with refractory cardiac arrest, ECPR may provide temporary support as a bridge to intervention or recovery. We report favourable survival and neurological outcomes in one third of patients and pre-ECMO lactate levels predictive of mortality. Further studies are required to determine optimum selection criteria for ECPR.

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.