Marcel Ricklefs

Electromechanical Assessment of Human Knee Articular Cartilage with Compression-Induced Streaming Potentials

Purpose: To assess the electromechanical properties of human knee articular cartilage with compression-induced streaming potentials for reliability among users and correlation with macroscopic and histological evaluation tools and sulfated glycosaminoglycan (sGAG) content. Methods: Streaming potentials are induced in cartilage in response to loading when mobile positive ions in the interstitial fluid temporarily move away from negatively charged proteoglycans. Streaming potential integrals (SPIs) were measured with an indentation probe on femoral condyles of 10 human knee specimens according to a standardized location scheme. Interobserver reliability was measured using an interclass correlation coefficient (ICC). The learning curves of 3 observers were evaluated by regression analysis. At each SPI measurement location the degradation level of the tissue was determined by means of the International Cartilage Repair Society (ICRS) score, Mankin score, and sGAG content. Results: The computed ICC was 0.77 (0.70-0.83) indicating good to excellent linear agreement of SPI values among the 3 users. A significant positive linear correlation of the learning index values was observed for 2 of the 3 users. Statistically significant negative correlations between SPI and both ICRS and Mankin scores were observed (r = 0.502, P < 0.001, and r = 0.255, P = 0.02, respectively). No correlation was observed between SPI and sGAG content (r = 0.004, P = 0.973). Conclusions: SPI values may be used as a quantitative means of cartilage evaluation with sufficient reliability among users. Due to the significant learning curve, adequate training should be absolved before routine use of the technique.

One year outcomes with the HeartMate 3 left ventricular assist device

Background The HeartMate 3 (HM3; Abbott Laboratories, Lake Forest, Ill) left ventricular assist device (LVAD) received its Conformité Européenne mark for Europe in October 2015 and is currently under investigation of the Food and Drug Administration to gain approval in the United States. Within this study, we present the first real‐world experiences, 1‐year outcomes, and adverse events of a single‐center cohort treated with the HM3. Methods We prospectively studied midterm results of 27 consecutive patients receiving the HM3 at a single institution. After HM 3 implantation, survival, causes of death, and complications were recorded for all patients. Follow up was 100% complete. Results Twenty‐seven patients were enrolled into the study. Within 1 year after HM3 implantation, 3 patients underwent heart transplantation and 3 patients died. Thirty‐day survival was 88.9%, 6‐month 85.2%, and 1‐year survival 85.2%. No pump thrombosis and no strokes were observed within the study group. One incident of gastrointestinal bleeding was observed (3.7%). Right heart failure was diagnosed in 1 patient after HM3 implantation (3.7%). No technical complications of the pump were documented. No pump exchanges were necessary. The main complication was LVAD‐related infection (22.2%). Conclusions The novel LVAD HM3 has already shown excellent Conformité Européenne mark trial results. Within this cohort, 1‐year survival after HM3 implantation was 85%. The HM3 showed excellent midterm results with 0% stroke and 0% pump thrombosis rates 1 year after implantation.

Wearable Cardioverter–Defibrillators following Cardiac Surgery—A Single-Center Experience

Background A wearable cardioverter‐defibrillator (WCD) can terminate ventricular fibrillation and ventricular tachycardias via electrical shock and thus give transient protection from sudden cardiac death. We investigated its role after cardiac surgery. Methods We retrospectively analyzed all patients who were discharged with a WCD from cardiac surgery department. The WCD was prescribed for patients with a left ventricular ejection fraction (LVEF) of ≤35% or an explanted implantable cardioverter‐defibrillator (ICD). Results A total of 100 patients were included in this study, the majority (n = 59) had received coronary artery bypass graft surgery. The median wearing time of a WCD patient was 23.5 hours per day. LVEF was 28.9 ± 8% after surgery and improved in the follow‐up to 36.7 ± 11% (p < 0.001). Three patients were successfully defibrillated. Ten patients experienced ventricular tachycardias. No inappropriate shocks were given. An ICD was implanted in 25 patients after the WCD wearing period. Conclusion Ventricular arrhythmias occurred in 13% of the investigated patients. LVEF improved significantly after 3 months, and thus a permanent ICD implantation was avoided in several cases. Sternotomy did not impair wearing time of the WCD. A WCD can effectively protect patients against ventricular tachyarrhythmias after cardiac surgery.

MitraClip procedure prior to left ventricular assist device implantation

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.

Less Invasive Surgical Approaches for Left Ventricular Assist Device Implantation

For several years, the standard implantation strategy of ventricular assist devices has involved a full sternotomy approach. However, less invasive implantation techniques are now becoming increasingly popular as they are associated with reduction of trauma, blood loss, and arrhythmogenic complications, as well as a decreased duration of intensive care unit and in-hospital stay. Thus, due to miniaturization and increasing technical improvement of ventricular assist devices, less invasive strategies for implantation, explantation, exchange, and concomitant cardiac procedures are on the rise. In this review article, we report on the state of the art of less invasive techniques for implantation, explantation, exchange, and combined cardiac procedures of ventricular assist devices.

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

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.

Successful HeartMate 3 implantation in isolated right heart failure—first in man experience of right heart configuration

In this article, we present the case of a 72-year-old male patient suffering from a severe form of singular isolated end-stage right heart failure based on arrhythmogenic right ventricular cardiomyopathy (ARVC), who was admitted to our clinic for acute cardiac decompensation.

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

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.

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

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.Conclusions: 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.

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

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 vs. 30% (n=10) group 2, P=0.004]. The 5-year mortality was lower in group 2 [42% (n=15) group 1 vs. 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 vs. 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.