Aron Frederik Popov

Early outcomes of bilateral sequential single lung transplantation after ex-vivo lung evaluation and reconditioning

BACKGROUND Ex vivo lung perfusion (EVLP) is a novel approach for extended evaluation and/or reconditioning of donor lungs not meeting standard International Society for Heart and Lung Transplantation criteria for transplantation. METHODS We retrospectively evaluated 13 consecutive EVLP runs between January 2009 and December 2010. Lungs rejected for routine transplantation were implanted to the EVLP circuit and reperfused using acellular supplemented Steen Solution (Vitrolife, Göteborg, Sweden) up to a target flow rate of 40% of the donors calculated flow at a cardiac index of 3.0 liters/min/m(2); target left atrial pressure < 5 mm Hg; and pulmonary artery pressure < 15 mm Hg. Mechanical ventilation was introduced after rewarming to 32°C: tidal volume, 6 to 8 ml/kg; respiratory rate, 7 to 8 breaths/min; duration of inspiration/expiration (I/E) ratio, 1:2; and positive end-expiratory pressure, 5 to 10 cm H(2)O. Hemodynamic and respiratory data monitoring with hourly clinical assessment were performed. Donor data, conversion rate to transplantation, and recipient outcome were analyzed. RESULTS Donor data (n = 13) were: age, 44.23 ± 8.33 years; female/male, 8:5; cause of death: intracranial hemorrhage, 11 (85%), stroke, 1 (7.5%), hypoxic brain injury, 1 (7.5%); smoking history, 9 (69%), 17.44 ± 8.92 pack-years; mechanical ventilation, 102.6 ± 91.92 hours; chest x-ray imaging: abnormal, 12 (92.5%); normal, 1 (7.5%). EVLP: mean 141 ± 28.83 minutes. Arterial partial pressure of oxygen/fraction of inspired oxygen 100% before termination of the circuit vs pre-retrieval value: 57.32 ± 9.1 vs 42.36 ± 14.13 kPa (p < 0.05). Six (46%) pairs of donor lungs were transplanted. Median follow-up was 297.5 days (range, 100-390 days), with 100% survival at 3 months. CONCLUSIONS EVLP may facilitate assessment and/or reconditioning of borderline lungs, with a conversion rate of 46 % and good short-term survival.

Clinical Experience With HeartWare Left Ventricular Assist Device in Patients With End-Stage Heart Failure

BACKGROUND The gold standard treatment for end-stage heart failure is cardiac transplantation. Because of the increasing number of heart failure patients and the limited supply of donor hearts, a ventricular assist device (VAD) is used as a bridge to transplantation, recovery, or decision. Newer generation VADs have lower risk of fatal adverse events and are also smaller in size. We present our experience with the intrapericardial HeartWare VAD (HeartWare, Framingham, MA) and its clinical outcome. METHODS The clinical outcome of HeartWare VAD implantations for end-stage heart failure patients performed at Harefield Hospital from March 2007 to June 2011 was studied. The study design was a retrospective review of the prospectively collected data. RESULTS Thirty-four patients with a mean age of 51±10 years were included in this study. Twenty-nine patients were male (85%). The mean duration of mechanical support was 261±64 days. Five patients (15%) were successfully bridged to heart transplantation. The overall mortality was 24% (8 patients). There were 1 case of mechanical device failure (2%) and 3 cases of device failure due to thrombus formation (8%). Postoperative complications included 5 reoperations for bleeding (15%), 12 acute renal failures (36%), 7 respiratory failures (21%), 2 hepatic dysfunctions (6%), 3 neurologic dysfunctions (9%), 7 right-side heart failures (21%), and 5 driveline infections (15%). CONCLUSIONS Although cardiac transplantation remains the gold standard for treatment of end-stage heart failure patients, the HeartWare VAD can be used as a safe alternative with a satisfactory clinical outcome.

HeartWare Left Ventricular Assist Device Implantation Through Bilateral Anterior Thoracotomy

The HeartWare left ventricular assist device (LVAD) is a new addition to the family of second-generation continuous-flow LVADs. The miniaturized dimensions of the HeartWare LVAD provide the opportunity for its safe implantation through nonsternotomy incisions. We present our technique for HeartWare LVAD implantation through bilateral anterior thoracotomy incisions. This technique has proved to be safe and reproducible, with good clinical outcome.

Surgical pleth index-guided remifentanil administration reduces remifentanil and propofol consumption and shortens recovery times in outpatient anaesthesia

BACKGROUND The surgical pleth index (SPI) is an index based on changes in plethysmographic characteristics that correlate with the balance between the sympathetic and parasympathetic nervous system. It has been proposed as a measure of the balance between nociception and anti-nociception. The goal of this study was to test whether it could be used to titrate remifentanil in day-case anaesthesia. METHODS A total of 170 outpatients were given total i.v. anaesthesia with propofol and remifentanil. The patients were randomized to have the remifentanil dose either adjusted according to the SPI (SPI group) or to clinical parameters (control group). The propofol dose was adjusted according to entropy in both groups. The consumption of anaesthetic drugs, recovery times, and complications were compared. RESULTS The mean [standard deviation (SD)] remifentanil and propofol infusion rates in the SPI and control groups were 0.06 (0.04) vs 0.08 (0.05) µg kg(-1) min(-1) and 6.0 (2.1) vs 7.5 (2.2) mg kg(-1) h(-1), respectively (both P<0.05). The mean (SD) times to eye opening were -0.08 (4.4) and 3.5 (4.3) min and to extubation were 1.2 (4.4) and 4.4 (4.5) min in the SPI and control groups, respectively (both P<0.05). There was no difference between the groups with regard to satisfaction with the anaesthetic or intensity of postoperative pain. No patient reported intraoperative awareness. CONCLUSIONS Adjusting the remifentanil dosage according to the SPI in outpatient anaesthesia reduced the consumption of both remifentanil and propofol and resulted in faster recovery.

De Novo Aortic Regurgitation After Continuous-Flow Left Ventricular Assist Device Implantation

BACKGROUND Significant aortic regurgitation (AR) after continuous-flow left ventricular assist device (cf-LVAD) placement affects device performance and patient outcomes. This study examined the development of AR and long-term results after implantation of cf-LVADs. METHODS The study included all patients with no or less than mild AR who underwent HeartMate II (58 [62%]; Thoratec Corp, Pleasanton, CA) or HeartWare (35 [38%]; HeartWare International, Framingham, MA) implantation at our institute from July 2006 to July 2012. Serial echocardiograms were obtained preoperatively, at 1, 3 and 6 months postoperatively, and then at a minimum of 4-month intervals in patients with longer-term support. Kaplan-Meier estimates for freedom from moderate or greater AR were generated. Logistic regression analysis was used to define independent predictors of AR after cf-LVAD implantation. RESULTS Median duration of LVAD support was 527 days (25(th), 75(th): 289, 907; range, 60 to 2,433 days). Mild AR developed in 48 patients (51.6%) over a median duration of 126 days, with progression to moderate AR in 13 (14%) over 493 days and to severe AR in 2 (2.1%) over 1,231 days. The incidence of mild or greater AR was 43.1% in HeartMate II vs 65.7% in HeartWare recipients (p = 0.035). Overall freedom from moderate or greater AR was 94.7% ± 2.6% at 1 year, 86.9% ± 4.5% at 2 years, 82.8% ± 5.9% at 3 years, and 31% ± 16.9% at 4 years. Independent predictors of AR were duration of support (odds ratio, 1.002; 95% confidence interval, 1.000 to 1.004; p = 0.017) and a persistently closed aortic valve (odds ratio, 0.193; 95% confidence interval, 0.097 to 0.382; p < 0.001). CONCLUSIONS AR is associated with longer cf-LVAD support duration and persistent aortic valve closure. Incidence of moderate or greater AR after cf-LVAD implantation increases significantly after 3 years. The clinical implications of these data may warrant consideration of prophylactic aortic valve replacement at the time of cf-LVAD implantation, particularly with expected longer duration of support and in patients with preexisting AR that is more than mild.

Bioartificial Heart: A Human-Sized Porcine Model – The Way Ahead

Background A bioartificial heart is a theoretical alternative to transplantation or mechanical left ventricular support. Native hearts decellularized with preserved architecture and vasculature may provide an acellular tissue platform for organ regeneration. We sought to develop a tissue-engineered whole-heart neoscaffold in human-sized porcine hearts. Methods We decellularized porcine hearts (n = 10) by coronary perfusion with ionic detergents in a modified Langendorff circuit. We confirmed decellularization by histology, transmission electron microscopy and fluorescence microscopy, quantified residual DNA by spectrophotometry, and evaluated biomechanical stability with ex-vivo left-ventricular pressure/volume studies, all compared to controls. We then mounted the decellularized porcine hearts in a bioreactor and reseeded them with murine neonatal cardiac cells and human umbilical cord derived endothelial cells (HUVEC) under simulated physiological conditions. Results Decellularized hearts lacked intracellular components but retained specific collagen fibers, proteoglycan, elastin and mechanical integrity; quantitative DNA analysis demonstrated a significant reduction of DNA compared to controls (82.6±3.2 ng DNA/mg tissue vs. 473.2±13.4 ng DNA/mg tissue, p<0.05). Recellularized porcine whole-heart neoscaffolds demonstrated re-endothelialization of coronary vasculature and measurable intrinsic myocardial electrical activity at 10 days, with perfused organ culture maintained for up to 3 weeks. Conclusions Human-sized decellularized porcine hearts provide a promising tissue-engineering platform that may lead to future clinical strategies in the treatment of heart failure.

Distal Limb Perfusion: Achilles' Heel in Peripheral Venoarterial Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is a temporary mechanical circulatory assist method that offers circulatory as well as respiratory support efficiently via peripheral access; however, it is liable to complications. Limb ischemia is one of the notorious complications of ECMO but can be avoided utilizing a proper distal limb perfusion method. A retrospective study of patients undergoing peripheral venoarterial (VA) ECMO for various reasons between June 2010 and December 2012 was performed. All patients were evaluated by our multidisciplinary team for suitability as candidates for ECMO. A peripheral VA-ECMO circuit was implanted via groin: inflow cannula in the femoral vein, an outflow cannula and distal-perfusion cannula, or an introducer sheath in the femoral artery. During the study period, 83 patients underwent various types of ECMO; 45 received peripheral VA-ECMO. Distal limb perfusion was achieved with an introducer sheath (6-8 Fr) in 13 cases and with a distal-perfusion cannula (10-12 Fr) in 32 cases. Nine (20%) patients developed signs of ischemia; five (11.2%) were treated conservatively, while four (8.8%) required surgical intervention. One patient required a below-knee amputation. The incidences of limb ischemia and limb ischemia requiring surgical intervention were significantly higher for the introducer sheath compared with the cannula (30.6 vs. 15.6% and 15.4 vs. 6.25%, respectively). Moreover, the patients supported on ECMO with a distal-perfusion cannula spent a significantly longer time on ECMO compared with the ones in whom an introducer sheath was used (11.9 ± 9.1 vs. 7.7 ± 4.3 days). The mean cannula size was significantly greater than the mean introducer sheath size (11.1 ± 1.3 vs. 7.0 ± 1.1 Fr). Use of a distal-perfusion cannula is a most reliable method of limb perfusion in peripheral VA-ECMO. The cannula can ensure adequate and smooth perfusion of the limb owing to its large caliber, its less turbulent flow, the ability it provides to monitor the flow, and the option to attach a side port.

HeartWare miniaturized intrapericardial ventricular assist device: advantages and adverse events in comparison to contemporary devices.

Increasing incidence of end-stage heart failure and limited availability of donor organs have led to longer waiting times for cardiac transplantation and subsequently increasing mortality. Ventricular assist device therapy is fast becoming an accepted alternative treatment to treat end-stage heart failure and is being implemented as a bridge to decision, bridge to myocardial recovery, bridge to heart transplantation or as a destination therapy. LVADs not only enable hemodynamic stabilization and recovery of secondary organ failure in severely ill patients, but have also been shown to reduce pulmonary vascular resistance in nontransplantable candidates. Technology of ventricular assist devices has evolved over several decades of time and generations of devices. The HVAD® Pump (HeartWare International, Inc., MA, USA) is a third-generation, miniaturized, continuous-flow ventricular assist device. Due to its miniaturized housing and intrapericardial placing, it can be used proficiently to support the right ventricle and has also demonstrated great utility in minimally invasive and off-pump implantation, exchange and explantation. It is favored for similar reasons in adolescents and in heart failure due to complex congenital heart disease. The purpose of this article is to review the clinical use of HeartWare® Ventricular Assist System (HeartWare System; HeartWare International, Inc.) with different strategies pertaining to its advantages and adverse events in comparison with contemporary devices.

Mild metabolic acidosis impairs the β-adrenergic response in isolated human failing myocardium.

IntroductionPronounced extracellular acidosis reduces both cardiac contractility and the β-adrenergic response. In the past, this was shown in some studies using animal models. However, few data exist regarding how the human end-stage failing myocardium, in which compensatory mechanisms are exhausted, reacts to acute mild metabolic acidosis. The aim of this study was to investigate the effect of mild metabolic acidosis on contractility and the β-adrenergic response of isolated trabeculae from human end-stage failing hearts.MethodsIntact isometrically twitching trabeculae isolated from patients with end-stage heart failure were exposed to mild metabolic acidosis (pH 7.20). Trabeculae were stimulated at increasing frequencies and finally exposed to increasing concentrations of isoproterenol (0 to 1 × 10-6M).ResultsA mild metabolic acidosis caused a depression in twitch-force amplitude of 26% (12.1 ± 1.9 to 9.0 ± 1.5 mN/mm2; n = 12; P < 0.01) as compared with pH 7.40. Force-frequency relation measurements yielded no further significant differences of twitch force. At the maximal isoproterenol concentration, the force amplitude was comparable in each of the two groups (pH 7.40 versus pH 7.20). However, the half-maximal effective concentration (EC50) was significantly increased in the acidosis group, with an EC50 of 5.834 × 10-8M (confidence interval (CI), 3.48 × 10-8 to 9.779 × 10-8; n = 9), compared with the control group, which had an EC50 of 1.056 × 10-8M (CI, 2.626 × 10-9 to 4.243 × 10-8; n = 10; P < 0.05), indicating an impaired β-adrenergic force response.ConclusionsOur data show that mild metabolic acidosis reduces cardiac contractility and significantly impairs the β-adrenergic force response in human failing myocardium. Thus, our results could contribute to the still-controversial discussion about the therapy regimen of acidosis in patients with critical heart failure.

Primary bacteraemia is associated with a higher mortality risk compared with pulmonary and intra-abdominal infections in patients with sepsis: a prospective observational cohort study

Objective To investigate whether common infection foci (pulmonary, intra-abdominal and primary bacteraemia) are associated with variations in mortality risk in patients with sepsis. Design Prospective, observational cohort study. Setting Three surgical intensive care units (ICUs) at a university medical centre. Participants A total of 327 adult Caucasian patients with sepsis originating from pulmonary, intra-abdominal and primary bacteraemia participated in this study. Primary and secondary outcome measures The patients were followed for 90 days and mortality risk was recorded as the primary outcome variable. To monitor organ failure, sepsis-related organ failure assessment (Sequential Organ Failure Assessment, SOFA) scores were evaluated at the onset of sepsis and throughout the observational period as secondary outcome variables. Results A total of 327 critically ill patients with sepsis were enrolled in this study. Kaplan-Meier survival analysis showed that the 90-day mortality risk was significantly higher among patients with primary bacteraemia than among those with pulmonary and intra-abdominal foci (58%, 35% and 32%, respectively; p=0.0208). To exclude the effects of several baseline variables, we performed multivariate Cox regression analysis. Primary bacteraemia remained a significant covariate for mortality in the multivariate analysis (HR 2.10; 95% CI 1.14 to 3.86; p=0.0166). During their stay in the ICU, the patients with primary bacteraemia presented significantly higher SOFA scores than those of the patients with pulmonary and intra-abdominal infection foci (8.5±4.7, 7.3±3.4 and 5.8±3.5, respectively). Patients with primary bacteraemia presented higher SOFA-renal score compared with the patients with other infection foci (1.6±1.4, 0.8±1.1 and 0.7±1.0, respectively); the patients with primary bacteraemia required significantly more renal replacement therapy than the patients in the other groups (29%, 11% and 12%, respectively). Conclusions These results indicate that patients with sepsis with primary bacteraemia present a higher mortality risk compared with patients with sepsis of pulmonary or intra-abdominal origins. These results should be assessed in patients with sepsis in larger, independent cohorts.