Publications by authors named "Anamika Chatterjee"

27 Publications

  • Page 1 of 1

Lateral Thoracotomy for Ventricular Assist Device Implantation: A Meta-Analysis of Literature.

ASAIO J 2021 Feb 4. Epub 2021 Feb 4.

From the *Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany †Department of Cardiology and Angiology, Hannover Medical School, Hannover, Germany ‡Cardio-Thoracic Surgery Department, Maastricht University Medical Centre (MUMC), Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands.

The use of lateral thoracotomy (LT) for implanting left ventricular assist devices (LVADs) is worldwide increasing, although the available evidence for its positive effects compared with conventional sternotomy (CS) is limited. This systematic review and meta-analysis analyzes the outcomes of LT compared with CS in patients undergoing implantation of a centrifugal continuous-flow LVAD. Four databases and 1,053 publications were screened until December 2019. Articles including patients undergoing implantation of a centrifugal continuous-flow LVAD through LT were included. A meta-analysis to compare LT and CS was performed to summarize evidences from studies including both LT and CS patients extracted from the same population. Primary outcome measure was in-hospital or 30-day mortality. Eight studies reporting on 730 patients undergoing LVAD implantation through LT (n = 242) or CS (n = 488) were included in the meta-analysis. Left thoracotomy showed lower in-hospital/30-day mortality (odds ratio [OR]: 0.520, 95% confidence interval [CI]: 0.27-0.99, p = 0.050), shorter intensive care unit (ICU) stay (mean difference [MD]: 3.29, CI: 1.76-4.82, p < 0.001), lower incidence of severe right heart failure (OR: 0.41; CI: 0.19-0.87, p = 0.020) and postoperative right ventricular assist device (RVAD) implantation (OR: 0.27, CI: 0.10-0.76, p = 0.010), fewer perioperative transfusions (MD: 0.75, CI: 0.36-1.14, p < 0.001), and lower incidence of renal failure (OR: 0.45, CI: 0.20-1.01, p = 0.050) and device-related infections (OR: 0.45, CI: 0.20-1.01, p = 0.050), respectively. This meta-analysis demonstrates that implantation of a centrifugal continuous-flow LVAD system via LT benefits from higher short-term survival, less right heart failure, lower postoperative RVAD need, shorter ICU stay, less transfusions, lower risk of device-related infections and kidney failure. Prospective studies are needed for further proof.
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http://dx.doi.org/10.1097/MAT.0000000000001359DOI Listing
February 2021

Flying after left ventricular assist device implantation.

Artif Organs 2021 Mar 20;45(3):230-235. Epub 2020 Oct 20.

Department of Cardiac-, Thoracic-, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Literature on the air travel activities of patients supported by permanent mechanical assist devices is rare. To the best of our knowledge, no air travel guidelines or fitness prerequisites exist on whether and when ventricular assist device (VAD) patients are allowed to travel by plane after device implantation. In this study, we evaluated the topic of air travel after VAD implantation. This working group aimed to produce a report on air travel passengers supported by VADs, regarding their fitness to fly. Fifty left ventricular assist device (LVAD) patients were surveyed in a worldwide multicenter study. The single survey was performed with a multimethod design, including interviews conducted face-to-face, online, and on phone. Out of 50 patients, 97% described their traveling by aircraft as perfect and uneventful during the flight. Eighty-five percent of the study participants consulted their medical practitioner before the flight. No patient reported the occurrence of a severe condition associated with flying. LVAD alarms, especially low flow alarms, did not occur in any of the devices. Thirty-five percent of the surveyed patients, however, stated a major problem pertaining to the security check procedures at the airport. The results of this study suggest that commercial air travel is safe for stable patients on permanent VAD support and traveling can be resumed securely after VAD implantation. Conscientious preparation by packing necessary devices, fluids, medications, and careful preparation for the airport security check is recommended.
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http://dx.doi.org/10.1111/aor.13815DOI Listing
March 2021

Minimally invasive left ventricular assist device implantation: optimizing device design for this approach.

Expert Rev Med Devices 2020 Apr 2;17(4):323-330. Epub 2020 Mar 2.

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

: The global heart failure (HF) burden is expected to increase due to aging populations, increasing number of end-stage HF patients and adverse lifestyle changes. Mechanical circulatory support (MCS) devices such as left ventricular assist devices (LVADs) have become a promising treatment option for short-term and long-term circulatory support of end-stage HF patients.: Recent developments in MCS technology have been focused on miniaturization leading to the development of minimally invasive surgical procedures for LVAD implantation. This helps overcome possible postoperative complications such as major incisions and poor outcomes due to infections, right heart failure, and bleeding. This article discusses clinical and technological developments in the field of minimally invasive procedures for LVAD implantation.: Most patients might benefit from minimally invasive LVAD implantation performed through a limited left lateral thoracotomy associated with an upper hemisternotomy or a right anterior thoracotomy. The thoracotomy approach can also be considered in case of pump exchange or pump explant. The success of these techniques is mainly based on the optimization of LVAD pump design, inflow cannula insertion, and outflow graft as well as driveline exit sites. The future direction of the LVAD field is likely to include less-invasive approaches and smartificial technologies.
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http://dx.doi.org/10.1080/17434440.2020.1735358DOI Listing
April 2020

Is this the right MOMENTUM?-evidence from a HeartMate 3 randomized trial.

J Thorac Dis 2019 Dec;11(12):5626-5630

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

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http://dx.doi.org/10.21037/jtd.2019.11.60DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6988041PMC
December 2019

Device profile of the heartware HVAD system as a bridge-to-transplantation in patients with advanced heart failure: overview of its safety and efficacy.

Expert Rev Med Devices 2019 Dec;16(12):1003-1015

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

: Heart failure (HF) is one of the rising problems in the contemporary society with growing incidences of end-stage HF. While heart transplantation (HT) is the gold standard treatment for end-stage HF, its availability is limited by the lack of heart donors. As a consequence, left ventricular assist devices (LVADs) are becoming key therapies as bridge to transplant (BTT) strategy to improve survival and outcomes.: A significant advancement for wider applications of LVADs as BTT was facilitated by the introduction of miniaturized pumps such as the HVAD (HeartWare®, Medtronic, MN, USA), allowing intrapericardial implants and less-invasive approaches. In this review article, we describe the technical features of the HVAD and its outcomes in terms of efficacy and safety when implanted as BTT strategy. Moreover, we discuss the postoperative results of HT in HVAD recipients and its application in the pediatric population.: It has been demonstrated that the HVAD positively influences the survival of end-stage HF patients awaiting HT, with an acceptable rate of adverse events. Due to its reduced size, it is particularly suitable for LVAD implantations through lateral thoracotomy and in patients with small thoracic dimensions.
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http://dx.doi.org/10.1080/17434440.2019.1696674DOI Listing
December 2019

Bioconversion of renewable feedstocks by Rhodococcus opacus.

Curr Opin Biotechnol 2020 08 30;64:10-16. Epub 2019 Sep 30.

Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, United States. Electronic address:

The production of fuels and chemicals from renewable feedstocks is necessary for a fossil fuel independent economy. Lignin and other industrial wastes represent sustainable, non-food feedstocks that can be tapped for microbe-based bioproduction. Rhodococcus opacus is a gram-positive bacterium capable of catabolizing a broad range of feedstocks, and recent technological advances have further established its potential for lignin and industrial waste valorization. In the process of developing R. opacus as a platform for bioproduction, metabolic profiling has elucidated its native mechanisms of bioconversion, adaptive evolution has enhanced its tolerance towards inhibitory feedstocks, and genetic engineering has enabled it to produce novel products, such as wax esters, free fatty acids, and long chain hydrocarbons. Here, we present recent examples of broad feedstock utilization and value-added chemical production by R. opacus, demonstrating its potential as an industrially relevant strain.
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http://dx.doi.org/10.1016/j.copbio.2019.08.013DOI Listing
August 2020

Initial experience with telemonitoring in left ventricular assist device patients.

J Thorac Dis 2019 Apr;11(Suppl 6):S853-S863

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Background: Left ventricular assist devices (LVAD) are increasingly used in patients with end stage heart failure. The HeartAssist 5 and aVAD LVADs offer telemetric monitoring capabilities. Here we report our initial single centre experience with the largest telemonitoring cohort of LVAD patients.

Methods: Eleven patients (9 males) received a telemonitoring-capable LVAD and were included in our telemonitoring cohort. Waveforms and alarm data were obtained from the telemonitoring system and hospital records were reviewed for clinical data.

Results: Mean age at LVAD implantation was 59±5.1 years (mean ± standard deviation). Seven patients had non-ischemic cardiomyopathy and 4 patients had ischemic cardiomyopathy. Median LVEF at implant was 16% (IQR, 15-20%). The total follow-up time was 2,438 patient-days. A total of 6,216 alarm messages were generated in 11 patients. Most common were low flow alarms due to hypovolemia, followed by low flow alarms because of suspected pump thrombosis. One patient died during follow-up, one received a cardiac transplant and one had the LVAD explanted because of pump thrombosis. Pump thrombosis was suspected in 5 patients with 8 episodes of sudden flow decreases and laboratory signs of haemolysis.

Conclusions: Real-time telemonitoring of LVAD pump flow, motor speed and power consumption is a promising tool in the follow-up of LVAD recipients. Trending pump flow over hours or days can assist in the early detection of complications, especially flow reductions due to hypovolemia and LVAD thrombosis. Further studies are warranted to delineate the impact of remote monitoring on patients' prognosis.
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http://dx.doi.org/10.21037/jtd.2018.10.37DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6535490PMC
April 2019

How to do it: tips and tricks of minimal-invasive HVAD implantation-the lateral approach.

J Thorac Dis 2018 Jun;10(Suppl 15):S1829-S1833

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

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http://dx.doi.org/10.21037/jtd.2018.05.149DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035961PMC
June 2018

A new tool for an explantation strategy of HeartMate 3™ left ventricular assist device.

J Thorac Dis 2018 Jun;10(Suppl 15):S1825-S1828

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Although rare, recovery of cardiac function after mechanical support of the left ventricle is the most desirable therapeutic goal in the treatment of end-stage heart failure.Herein, we present a novel implantable device for explantation of the HeartMate 3™ left ventricular assist device (LVAD) in patients, following cardiac recovery, avoiding (re-) sternotomy.This article demonstrates the feasibility of applying this novel device, which fits into the sewing ring of the LVAD.This custom-made mechanical plug offers a promising alternative to standard device-explantation procedures.
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http://dx.doi.org/10.21037/jtd.2018.04.57DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035945PMC
June 2018

The momentum of HeartMate 3: a novel active magnetically levitated centrifugal left ventricular assist device (LVAD).

J Thorac Dis 2018 Jun;10(Suppl 15):S1790-S1793

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Left ventricular assist devices (LVADs) are emerging as the treatment of choice for advanced heart failure due to the dearth of healthy donor hearts for cardiac transplantation. The HeartMate 3 LVAD is a novel centrifugal pump which was developed to provide hemodynamic support in heart failure patients, either as a bridge to transplant (BTT), myocardial recovery, or as destination therapy (DT). Technological and clinical advancements have led to optimized hemocompatibility and development of less invasive surgical procedures for the implantation of this pump. The worldwide first implantation of the HeartMate 3 was performed by Prof. Schmitto and his team at Hannover Medical School, Germany in 2014, paving the way for subsequent surgical developments. This article summarizes the advanced technological and clinical aspects of the HeartMate 3 and outlines future technical developments for safe and effective treatment of advanced heart failure.
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http://dx.doi.org/10.21037/jtd.2017.10.124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035956PMC
June 2018

Clinical overview of the HVAD: a centrifugal continuous-flow ventricular assist device with magnetic and hydrodynamic bearings including lateral implantation strategies.

J Thorac Dis 2018 Jun;10(Suppl 15):S1785-S1789

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Growing worldwide incidences of end-stage heart failure and declining rates of cardiac transplants have given rise to the need for alternative treatment options, based on mechanical circulatory support (MCS) devices such as left ventricular assist devices (LVADs). Technologically advanced LVADs such as the HVAD (HeartWare, Medtronic) facilitate safe and efficient treatment of heart failure patients with reduced post-operative complications, which is attributed to their considerably miniaturized size. This also facilitates the development and implementation of novel, minimally-invasive surgical techniques. The HVAD is a centrifugal pump, manufactured by HeartWare Inc., (Framingham, MA, USA) and subsequently by Medtronic Inc., (Minnesota, MN, USA), and has been approved for clinical application after receiving the CE Mark approval in 2008 and the FDA approval in 2012. Current research efforts are focused on further miniaturization alongside optimization of electronic and software controllers as well as implementation of the transcutaneous energy transfer (TET) technology. Salient features of the HVAD pump technology, clinical applications and future optimization strategies have been discussed in this article.
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http://dx.doi.org/10.21037/jtd.2018.04.148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035953PMC
June 2018

MitraClip procedure prior to left ventricular assist device implantation.

J Thorac Dis 2018 Jun;10(Suppl 15):S1763-S1768

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Background: Functional mitral valve regurgitation is a frequent consequence of left ventricular dysfunction in patients with severe heart failure and is associated with a poor prognosis. It is hypothesized that in this patient group the mitral valve repair, respectively replacement, improves hemodynamics and clinical symptoms. As operative interventions with the help of heart-lung-machine are high risk procedures in these cases, the transcatheter mitral repair with MitraClip (Abbott Vascular, IL, USA) has recently become frequently used. Most of these cases experience a progress in left ventricular dysfunction, which finally leads to in an implantation of a left ventricular assist device. In this report, we describe a series of six cases in which patients with end stage heart failure and consecutive functional mitral valve regurgitation were supported with a left ventricular assist device after MitraClip implantation. We aimed to investigate, whether the MitraClip implantation leads to an improvement of the hemodynamic prior left ventricular assist device (LVAD)-implantation.

Methods: We retrospectively analyzed the data of 6 patients (5 males, 1 female) with severe heart failure, who underwent LVAD implantation after the MitraClip procedure. The mean age at MitraClip procedure was 64.6 years, mean age at time of LVAD implantation was 65.5 years. The parameters examined were cardiac index (CI), left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD) and the pulmonary capillary wedge pressure (PCWP).

Results: All patients had functional mitral regurgitation (MR). Severity of MR was reduced successfully in all treated patients. All patients were discharged with MR I-II and NYHA functional class III or IV after MitraClip procedure. The mean CI was 2.93 before MitraClip procedure and 2.36 before LVAD-Implantation. Mean LVEDD was 71 mm before MitraClip, mean LVEDD was 70.6 mm before LVAD, and 63.2mm after LVAD implantation respectively. The mean PCWP was 21.5 mmHg before MitraClip and 19.8 mmHg before LVAD implantation respectively. The mean left ventricular ejection fraction (LVEF) was 19.2% before MitraClip, the mean LVEF was 17.6% before LVAD and 15% after LVAD implantation. Two of the LVAD implanted patients died due to post-operative complications. There were no complications after MitraClip procedure.

Conclusions: Our presented patient cohort presented little hemodynamic improvement after the MitraClip procedure. There was no clinical benefit for the patients after MitraClip procedure, progressing left ventricular dysfunction could not be prevented and resulted in subsequent LVAD implantation.
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http://dx.doi.org/10.21037/jtd.2018.05.36DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035960PMC
June 2018

The influence of less invasive ventricular assist device implantation on renal function.

J Thorac Dis 2018 Jun;10(Suppl 15):S1737-S1742

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Background: End-stage heart failure is associated with severe after-effects such as heart valve insufficiency, cardiac arrhythmias or end-organ dysfunctions. Renal failure or 'cardiorenal syndrome' is a critical end-organ disorder associated with advanced heart failure, which occurs due to low-output failure. Drug therapy or surgical interventions involving left ventricular assist device (LVAD) implantation may impede the progress of heart insufficiency and its after-effects including renal failure. In this study, we investigated the impact of a minimally invasive ventricular assist device implantation through upper hemisternotomy combined with anterolateral thoracotomy on renal function, in patients with perioperative renal failure.

Methods: We analyzed data obtained from 103 patients (80 males, 23 females; mean age 53.8±11.7) who underwent LVAD implantation at our clinic within a 15-year interval (2001-2016) and were dialyzed due to renal dysfunction. 90 patients were operated with the conventional LVAD implantation technique (standard approach surgery, SAS) and 13 underwent less invasive approach implantation (less invasive surgery, LIS).

Results: For all patients, data analysis showed significant increase of glomerular filtration rate (GFR) (44.2±56.48 mL/min; 95% CI: 33.81-55.28; P<0.001) along with a significant decrease in the levels of creatinine (-1.08±1.83 mg/dL; 95% CI: 0.75-1.46; P<0.001) and urea (-4.62±13.66 mmol/L; 95% CI: 1.95-7.29; P<0.001). There was a considerable difference in change of renal parameters in patients treated with LIS in comparison to patients who underwent SAS, which was however not statistically significant (GFR: P=0.494; creatinine: P=0.543; urea P=0.918).

Conclusions: LVAD implantation improves kidney function in patients with renal dysfunction. A considerable difference in the change of renal parameters was detected in patients with LIS as compared to SAS, which was not significant possibly due to the limited size of the patient cohort (n=13).
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http://dx.doi.org/10.21037/jtd.2017.10.03DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035947PMC
June 2018

Left ventricular assist device exchange for the treatment of HeartMate II pump thrombosis.

J Thorac Dis 2018 Jun;10(Suppl 15):S1728-S1736

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Background: Pump thrombosis is the most severe and acute complication of left ventricular assist device (LVAD) therapy and treatment remains challenging. Whilst lysis therapy is often not successful, the exchange of the occluded LVAD is currently the most applied therapeutic treatment for this event. With this study we examine the effects of minimal-invasive LVAD exchange on the rate re-thrombosis and outcomes as well as adverse events in the study group.

Methods: Between February 2004 and December 2015 more than 600 LVADs were implanted at our institution. We retrospectively studied a patient cohort of 41 patients who underwent LVAD exchange because of pump thrombosis at a single institution. Outcomes, rates of re-thrombosis and adverse events were analyzed.

Results: Between February 2004 and December 2015, 87 exchanges of LVADs were performed at a single center. In 41 cases pump thrombosis was the reason for LVAD exchange. A total of 28 patient years (10,276 days) were analyzed. Average ICU stay was 15.8±20.4 days and average in-hospital stay 38.1±37.3 days after LVAD exchange. After thirty days the survival rate was 80.5%, 75.6% after 6 months and 70.7% one year after LVAD exchange. Out of the study cohort, three patients have successfully undergone heart transplantation. Twelve patients suffered a stroke postoperatively (29%). Twelve patients needed postoperative dialysis (29%). No technical complications of the VAD were recorded in the study group. Two patients underwent successful LVAD explantation due to myocardial recovery. One year after LVAD exchange, 14 patients underwent re-exchange due to pump thrombosis (34%). Eight patients suffered from a LVAD related infection out of which two patients were treated by pump exchange. A total of 12 patients died during the complete one year follow up of this study (29%). Four patients died in the second, two in the third and one in the fourth year after LVAD exchange. The remaining 17 patients are still ongoing on the device. It is generally feasible to treat pump thrombosis via LVAD exchange. Yet, the exchange procedure is not without risk and the risk of re-thrombosis (34%), stroke (29%), postoperative dialysis (29%) and perioperative complications remains high.
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http://dx.doi.org/10.21037/jtd.2018.01.115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035958PMC
June 2018

Argatroban administration as therapy for thrombosis in patients with continuous-flow ventricular assist devices.

J Thorac Dis 2018 Jun;10(Suppl 15):S1720-S1727

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Background: Device thrombosis is one of the main complications in left ventricular assist devices (LVAD) therapy and remains a challenging issue. Data on device thrombosis management, especially on the application of direct thrombin inhibitors such as argatroban, is limited and a consensus on thrombosis management has not yet been established.

Methods: In this study we analysed retrospective clinical data obtained from 26 patients on VAD therapy who received argatroban for suspected VAD thrombosis, between April, 2012 and February, 2017.

Results: Thirteen patients (50%) showed resolution of thrombus after argatroban therapy. Eight of 26 patients (30.8%) were free of thrombotic events 90 days after discharge. Argatroban therapy was unsuccessful in 13 patients of the study cohort, leading to subsequent VAD-exchange. Six of 13 patients with first VAD-exchange had no thrombotic events 90 days after discharge. Six patients (23.1%) suffered from bleeding, especially gastrointestinal bleeding. No hemorrhagic strokes were observed. Three patients (11.5%) did not survive the follow-up period.

Conclusions: Argatroban appears to be an alternative to other pharmacological treatment options in VAD thrombosis. Efficacy and safety characteristics are acceptable, but further investigation on larger populations is necessary.
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http://dx.doi.org/10.21037/jtd.2017.10.164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035951PMC
June 2018

An acoustic method for systematic ventricular assist device thrombus evaluation with a novel artificial thrombus model.

J Thorac Dis 2018 Jun;10(Suppl 15):S1711-S1719

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Background: Pump thrombosis (PT) is still one of the major adverse events in patients supported with left ventricular assist devices. Nowadays, thrombus detection relies on clinical parameters like reoccurring heart failure symptoms, on changes in pump power consumption, and on laboratory parameters such as increased LDH and hemolysis. Once detected PT is most often persistent and refractory to medical therapy. We therefore designed a novel, non-invasive acoustic method for early pump thrombus detection in an artificial thrombus model.

Methods: The study was performed using a mock circulation loop, artificial blood (water-glycerin) and artificial thrombus material (silicon) allowing for repeatable and defined testing. Tested ventricular assist device (VAD) type was HVAD (Medtronic). Three different thrombus locations were evaluated: on the tilted pad of the rotor, in the primary flow path, and in the secondary flow path beneath the rotor. After evaluating baseline parameters (no thrombus, n=20 for each pump), the influence of thrombi of seven different masses (no thrombus, 0.5-5.0 mg) on pump power consumption and acoustic emission of four HVAD devices was investigated via a microphone system (Sennheiser) and subsequent frequency spectrum analysis (n=12). The acoustic analysis algorithm included the number of frequency peaks recorded.

Results: Measurements with thrombi on the tilted pad showed an increased number of frequency peaks with all thrombus sizes compared to baseline measurements without any thrombus (baseline: 32.7±7.4; 0.5 mg: 45.3±10.4 up to 5 mg: 80.4±5.5). Power consumption was relevantly elevated in 5mg thrombus measurement only (6.3±1.29 W compared to 4.9±0.14 W at baseline). Measurements with thrombi in the primary and secondary showed no relevant alteration in power consumption and frequency peak count.

Conclusions: We present an acoustic method that detects pump thrombi located on the tilted pad of the HVAD rotor requiring ten times less mass compared to thrombi detected by power consumption alterations used in current detection algorithms. Assuming that pump thrombi are growing over several days, the presented method may detect PT much earlier thereby increasing efficacy of medical therapy and helping to avoid pump exchange.
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http://dx.doi.org/10.21037/jtd.2018.04.11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035965PMC
June 2018

Reduction of driveline infections through doubled driveline tunneling of left ventricular assist devices-5-year follow-up.

J Thorac Dis 2018 Jun;10(Suppl 15):S1703-S1710

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Background: Driveline infection (DLI) is one of the leading causes for unplanned re-admissions of patients undergoing therapy with left ventricular assist devices (LVAD). In previous studies our group was able to show that a double tunneling implantation technique could significantly reduce infection rates one year after implantation. We now report the results of the five-year-follow up of patients receiving the double tunneling technique.

Methods: We retrospectively analyzed patients receiving LVAD therapy with the HeartWare ventricular assist device (HVAD) (Medtronic, Minnesota, MN, USA) LVAD. For 36 patients (group 1) the driveline was tunneled via a conventional technique. In the remaining 33 patients (group 2) the drivelines were implanted by means of a double tunneling technique. The double tunnel driveline technique involved placement of the driveline in the sheath of the rectus muscle in the umbilical direction and then subcutaneously to the left (alternatively right) upper quadrant. We retrospectively compared both groups. Primary outcome parameters were infection rate and mortality.

Results: Five years after LVAD implantation the DLI rate of patients operated by a double tunneling technique was significantly lower than in the conventional technique group [61% (n=22) group 1 30% (n=10) group 2, P=0.004]. The 5-year mortality was lower in group 2 [42% (n=15) group 1 27% (n=9) group 2] but did not achieve statistical significance (P=0.10). The days of LVAD support between the two groups were comparable (1,275.56±885.89 group 1 1,321.94±711.37 group 2). The tunnel technique itself showed to be strongly associated with the occurrence of DLI. Other elevated variables are liver disease and dilated cardiomyopathy as primary disease.

Conclusions: Double tunneling technique for driveline implantation leads to significantly lowered infection rates after 5 years of LVAD therapy and it is associated with a lower mortality.
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http://dx.doi.org/10.21037/jtd.2018.03.127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035948PMC
June 2018

Minimally invasive surgery improves outcome of left ventricular assist device surgery in cardiogenic shock.

J Thorac Dis 2018 Jun;10(Suppl 15):S1696-S1702

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Background: Left ventricular assist device (LVAD) (HVAD, Medtronic, Minneapolis, MN, USA) implantation is already a widely accepted treatment option for end-stage heart failure (HF) but also still considered as a rescue therapy for patients suffering from cardiogenic shock. Standard LVAD implantation techniques are often associated with high mortality rates and can result in severe complications, like bleeding or right heart failure (RHF). The aim of our study was to assess the outcome of Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) 1 patients (so called "crash and burn" patients) undergoing a LVAD implantation by standard or less invasive surgery.

Methods: We performed a retrospective evaluation of the 1-year outcome of 32 consecutive HF patients in cardiogenic shock, who underwent LVAD implantation in our institution. A total of 32 INTERMACS 1 patients were emergently operated. Fourteen patients (group A) were operated by using the "Hannover-VAD-technique", which is widely known to be less invasive (upper hemisternotomy and a left-sided anterolateral thoracotomy). In contrast, 18 patients (group B) were implanted with LVAD by using the standard technique (full sternotomy). The primary endpoint was survival after 1 year without device-related re-operations. Secondary endpoints included combined analyses of rates of RHF, respiratory failure and bleeding during the trial period.

Results: Baseline characteristics were similar in both groups. Survival after 1 year was higher in group A (69.7% 50.0%). Technique-related adverse events (AEs) were also lower in the minimally invasive group, including a lower RHF (35.7% 61.1%) and of further postoperative bleeding requiring surgery (14.3% 33.3%).

Conclusions: LVAD surgery in INTERMACS 1 patients is associated with remarkably good outcome considering the already very high mortality of those patients, and compared to previously reported surgical outcomes. Our study indicates that minimally invasive LVAD implantation in cardiogenic shock decreases mortality and the incidence of postoperative AEs.
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http://dx.doi.org/10.21037/jtd.2018.01.27DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035957PMC
June 2018

The evolution of mechanical circulatory support (MCS): a new wave of developments in MCS and heart failure treatment.

J Thorac Dis 2018 Jun;10(Suppl 15):S1688-S1691

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

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http://dx.doi.org/10.21037/jtd.2018.05.205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035950PMC
June 2018

In vitro study for the evaluation of transluminal aspiration as a novel treatment option for thrombosis in the HeartWare HVAD.

Int J Artif Organs 2018 Nov 18;41(11):764-771. Epub 2018 Jul 18.

1 Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Introduction:: Pump thrombosis of left ventricular assist devices remains a devastating complication with high morbidity and mortality. Despite the improvements made, the matter affects many patients and the treatment options are limited to thrombolysis and surgical replacement. An alternative approach using the aspiration Indigo catheter was tested.

Methods:: An Indigo thrombectomy catheter was used within an in vitro model to assess the direct aspiration of prefabricated clots from three different positions within the HeartWare HVAD (inlet, outlet, and housing). The experiments were conducted with a straight and an angled catheter. The aspiration pressure was constant. The flow, power consumption, and pressure head of the left ventricular assist devices were measured at pre-defined measuring points.

Results:: The device was more effective (success rate 71%) at inlet and outlet of the left ventricular assist device. In addition, the duration of aspiration and the aspiration volume were shorter in comparison to the aspiration in the housing (inlet M = 19.75 s, outlet M = 60.50 s, and housing M = 38.75 s). Moreover, the aspiration volume was associated with the aspiration duration and the weight of thrombi but not with their volume. Noteworthy, the angled catheter showed an improved performance compared to the straight one (67%-33%). The recorded parameters showed no major changes during the use of the catheter. After application of the Indigo catheter, flow and pressure head of the pump could be restored.

Conclusions:: The aspiration system showed promising results under specific conditions for the treatment of pump thrombosis in an in vitro model. However, further examination, including in vivo experiments, will justify its effectiveness.
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http://dx.doi.org/10.1177/0391398818785557DOI Listing
November 2018

Left Ventricular Assist Devices - A State of the Art Review.

Adv Exp Med Biol 2018 ;1067:287-294

Department of Cardiac-, Thoracic-, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

Cardiovascular diseases are the leading cause of mortality rates throughout the world. Next to an insufficient number of healthy donors, this has led to increasing numbers of patients on heart transplant waiting lists with prolonged waiting times. Innovative technological advancements have led to the production of ventricular assist devices that play an increasingly important role in end stage heart failure therapy. This review is intended to provide an overview of current implantable left ventricular assist devices, different design concepts and implantation techniques. Challenges such as infections and thromboembolic events that may occur during LVAD implantations have also been discussed.
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http://dx.doi.org/10.1007/5584_2018_145DOI Listing
October 2018

Novel centrifugal pump for heart failure patients: initial success and future challenges.

J Thorac Dis 2017 Jun;9(6):1429-1431

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.

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http://dx.doi.org/10.21037/jtd.2017.05.68DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5506138PMC
June 2017

Xeno-Free Cryopreservation of Bone Marrow-Derived Multipotent Stromal Cells from Callithrix jacchus.

Biopreserv Biobank 2016 Dec 7;14(6):530-538. Epub 2016 Sep 7.

Institute for Multiphase Processes, Leibniz Universität Hannover , Hannover, Germany .

In the previous decade, numerous biobanks were established and have created large markets for the storage of bioactive compounds, cells, and tissues for medical and diagnostic applications. For in vivo clinical and therapeutic purposes, it is critical to use well-defined and xeno-free components during cultivation, preservation, and transplantation of biological material. Safe and efficacious storage of bioactive molecules, cells, and tissues, without the addition of undefined medium components, minimizes risks of zoonotic disease transmission and is thus an essential and desirable prerequisite for biobanks. This gives rise to a need for well-characterized and serum-free freezing media for application in cryopreservation. For this purpose, cryobiological additives such as methylcellulose, poloxamer-188, and α-tocopherol, which have previously been shown to exhibit a cytoprotective activity, have been investigated for cryoprotection on stem cells. With this strategy, the application of fetal bovine serum (FBS) could be avoided and the concentration of toxic cryoprotective agents such as dimethyl sulfoxide (DMSO) could be reduced. Our results suggest that the viability, as well as the adipogenic and osteogenic differentiation capacity of the thawed bone marrow-derived multipotent stromal stem cells, could be maintained using a freezing medium without FBS consisting of methylcellulose, poloxamer, and α-tocopherol with only 2.5% DMSO (% v/v).
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http://dx.doi.org/10.1089/bio.2016.0038DOI Listing
December 2016

Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

Mater Sci Eng C Mater Biol Appl 2016 Nov 26;68:143-152. Epub 2016 May 26.

Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover, Germany. Electronic address:

Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application.
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http://dx.doi.org/10.1016/j.msec.2016.05.113DOI Listing
November 2016

Thermal Pretreatment Improves Viability of Cryopreserved Human Endothelial Cells.

Biopreserv Biobank 2015 Oct 29;13(5):348-55. Epub 2015 Sep 29.

Institute for Multiphase Processes, Leibniz Universitaet Hannover , Hannover, Germany .

A high survival rate of cryopreserved cells requires optimal cooling and thawing rates in the presence of a cryoprotective agent (CPA) or a combination of CPAs in adequate concentrations. One of the most widely used CPAs, dimethyl sulfoxide (Me2SO), however is toxic at high concentrations and has detrimental effects on cellular functions. Additional processing steps are necessary to remove the CPA after thawing, which make the process expensive and time consuming. Therefore it is of great interest to develop new cryoprotective strategies to replace the currently used CPAs or to reduce their concentration. The aim of this study was to investigate if thermal activation of human pulmonary microvascular endothelial cells (HPMEC ST-1.6R), prior to cryopreservation, could improve their post-thaw viability since the resulting heat shock protein expression acts as an intrinsic cellular protection mechanism. The results of this study suggest that both heat and cold shock pretreatments improve cryopreservation outcome of the HPMEC ST-1.6R cells. By re-cultivating cells after heat shock treatment before cryopreservation, a significant increase in cellular membrane integrity and adherence capacity could be achieved. However a combination of thermal activation and cryopreservation with alternative CPAs such as ectoine and L-proline could not further enhance the cell viability. The results of this study showed that pretreatment of endothelial cells with thermal activation could be used to reduce the Me2SO concentration required in order to preserve cell viability after cryopreservation.
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http://dx.doi.org/10.1089/bio.2015.0024DOI Listing
October 2015