Martin Schweiger

Biventricular Circulatory Support With Two Miniaturized Implantable Assist Devices

Background— Up to 30% of patients with end-stage heart failure experience biventricular failure that requires biventricular mechanical support. For these patients, only bulky extracorporeal or implantable displacement pumps or the total artificial heart have been available to date, which enables only limited quality of life for the patients. It was our goal to evaluate a method that would allow the use of 2 implantable centrifugal left ventricular assist devices as a biventricular assist system. Methods and Results— Seventeen patients have been implanted with 2 HeartWare HVAD pumps, 1 as a left ventricular assist device and 1 as a right ventricular assist device. Seventy-seven percent of the patients had idiopathic dilated or ischemic cardiomyopathy. Their age ranged from 29 to 73 years (mean 51.8±14.5 years), and 11 (64.7%) received intravenous catecholamine support preoperatively. The right ventricular assist device pump was implanted into the right ventricular free wall. The afterload of this pump was artificially increased by local reduction of the outflow graft diameter, and the effective length of its inflow cannula was reduced by the addition of two 5-mm silicon suture rings to the original HVAD implantation ring. All right ventricular assist device devices could be operated in appropriate speed ranges and delivered a flow of between 3.0 and 5.5 L/min. Thirty-day survival was 82%, and 59% of the patients could be discharged home after recovering from the operation. There was no clinically relevant hemolysis in any of the patients. Conclusions— Two HeartWare HVAD pumps can be used as a biventricular assist system. This implantable biventricular support gives the patients more comfort and mobility than usual biventricular ventricular assist devices with large and noisy displacement pumps.

Off-the-shelf human decellularized tissue-engineered heart valves in a non-human primate model

Heart valve tissue engineering based on decellularized xenogenic or allogenic starter matrices has shown promising first clinical results. However, the availability of healthy homologous donor valves is limited and xenogenic materials are associated with infectious and immunologic risks. To address such limitations, biodegradable synthetic materials have been successfully used for the creation of living autologous tissue-engineered heart valves (TEHVs) in vitro. Since these classical tissue engineering technologies necessitate substantial infrastructure and logistics, we recently introduced decellularized TEHVs (dTEHVs), based on biodegradable synthetic materials and vascular-derived cells, and successfully created a potential off-the-shelf starter matrix for guided tissue regeneration. Here, we investigate the host repopulation capacity of such dTEHVs in a non-human primate model with up to 8 weeks follow-up. After minimally invasive delivery into the orthotopic pulmonary position, dTEHVs revealed mobile and thin leaflets after 8 weeks of follow-up. Furthermore, mild-moderate valvular insufficiency and relative leaflet shortening were detected. However, in comparison to the decellularized human native heart valve control - representing currently used homografts - dTEHVs showed remarkable rapid cellular repopulation. Given this substantial in situ remodeling capacity, these results suggest that human cell-derived bioengineered decellularized materials represent a promising and clinically relevant starter matrix for heart valve tissue engineering. These biomaterials may ultimately overcome the limitations of currently used valve replacements by providing homologous, non-immunogenic, off-the-shelf replacement constructs.

Is Bridge to Recovery More Likely With Pulsatile Left Ventricular Assist Devices Than With Nonpulsatile-Flow Systems?

BACKGROUND Weaning from left ventricular assist devices (LVADs) after myocardial recovery in patients with idiopathic dilated cardiomyopathy is a clinical option. With the broad application of continuous-flow pumps, we observed a decrease in the numbers of possible LVAD explanations due to myocardial recovery in these particular patients. We investigated this phenomenon and its causes. METHODS Between July 1992 and December 2009, 387 patients (age, 0.1 to 82 years) with idiopathic dilated cardiomyopathy underwent LVAD implantation at our institution. Patients were divided into two groups depending on whether they were weaned from the LVAD (group A) or not (group B). Univariate and multivariate analyses were performed on 24 different factors with a possible influence on myocardial recovery. RESULTS In 34 patients, LVAD removal due to myocardial recovery was performed with long-term stable cardiac function (weaning rate, 8.8%). Patients with a pulsatile-flow LVAD had an almost threefold chance for myocardial recovery (odds ratio, 2.719; 95% confidence interval, 1.182 to 6.254) than patients who received continuous-flow devices. Younger patients had significantly higher recovery rates than older patients (odds ratio, 1.036; 95% confidence interval, 1.016 to 1.057). CONCLUSIONS Pulsatile-flow LVADs and young age were important factors for myocardial recovery in idiopathic dilated cardiomyopathy patients in our analysis. Further studies should investigate whether pulsatility in itself or the different degrees of left ventricular unloading by the two types of systems play a role in myocardial recovery.

Modified Blalock Taussig shunt: a not-so-simple palliative procedure

OBJECTIVES Thirty-two consecutive isolated modified Blalock Taussig (BT) shunts performed in infancy since 2004 were reviewed and analysed to identify the risk factors for shunt intervention and mortality. METHODS Sternotomy was the only approach used. Median age and weight were 10.5 (range 1-74) days and 2.9 (1.9-4.4) kg, respectively. Shunt palliation was performed for biventricular hearts (Tetralogy of Fallot/double outlet right ventricle/transposition of great arteries_ventricular septal defect_pulmonary stenosis/pulmonary atresia_ventricular septal defect/others) in 21, and univentricular hearts in 11, patients. Hypoplastic left heart syndrome patients were excluded. Two procedures required cardiopulmonary bypass. Median shunt size was 3.5 (3-4) mm and median shunt size/kg body weight was 1.2 (0.9-1.7) mm/kg. Reduction in shunt size was necessary in 5 of 32 (16%) patients. RESULTS Three of 32 (9%) patients died after 3 (1-15) days due to cardiorespiratory decompensation. Lower body weight (P = 0.04) and bigger shunt size/kg of body weight (P = 0.004) were significant risk factors for mortality. Acute shunt thrombosis was observed in 3 of 32 (9%), none leading to death. Need for cardiac decongestive therapy was associated with univentricular hearts (P < 0.001), bigger shunt size (P = 0.054) and longer hospital stay (P = 0.005). Twenty-eight patients have undergone a successful shunt takedown at a median age of 5.5 (0.5-11.9) months, without late mortality. CONCLUSIONS Palliation with a modified BT shunt continues to be indicated despite increased thrust on primary corrective surgery. Though seemingly simple, it is associated with significant morbidity and mortality. Effective over-shunting and acute shunt thrombosis are the lingering problems of shunt therapy.

Outpatient management of intra-corporeal left ventricular assist device system in children: a multi-center experience.

Little is known about the outcomes of children supported on intracorporeal left ventricular assist device (HVAD), and the feasibility of outpatient management. All centers with pediatric patients discharged from the hospital on the device were identified using company database. A total of 14 centers were contacted, with 9 centers, contributing data retrospectively. From 2011 to 2013, 12 pediatric patients (7 females), mean aged 11.9 ± 2.3 years (range 8–15), mean weight 43 ± 19 kg (range 18–81), mean body surface area 1.3 ± 0.3 m2 (range 0.76–1.96) were identified. Diagnosis included: dilated cardiomyopathy (CMP) (n = 5), noncompaction CMP (n = 4), toxic CMP (n = 2) and viral CMP (n = 1). Indications for support were permanent support (n = 1), bridge to recovery (n = 1) and bridge to transplantation (n = 10). Prior to HVAD implantation, all patients received intravenous inotropes and two patients were on temporary mechanical support. Overall mortality was 0%. Mean duration of inpatient and outpatient support were 56 (range: 19–95 days) and 290 days (range: 42–790), respectively. Mean readmission rate was 0.02 per patient month (2.1 per patient). No adverse events involving emergency department occurred. Eight children resumed local schooling. Home discharge of children supported on HVAD is feasible and safe. School integration can be achieved. There is wide center variability to discharge practice for children.

Temporary right ventricular mechanical support in high-risk left ventricular assist device recipients versus permanent biventricular or total artificial heart support.

Early planned institution of temporary right ventricular assist device (RVAD) support with the CentriMag (Levitronix LLC, Waltham, MA, USA) in left ventricular assist device (LVAD) recipients was compared with permanent biventricular assist device (BVAD) or total artificial heart (TAH) support. Between 2007 and 2011, 77 patients (age range: 25-70 years) with preoperative evidence of biventricular dysfunction (University of Pennsylvania score >50; University of Michigan score >5) were included. Forty-six patients (38 men; median age 54.5 years, range: 25-70 years) underwent LVAD placement combined with temporary RVAD support (group A); in 31 patients (25 men; median age 56.7 years, range: 28-68 years), a permanent BVAD or TAH implantation (group B) was performed. Within 30 days, 12 patients from group A (26.08%) and 14 patients from group B (45.1%) died on mechanical support (P = 0.02). Thirty patients (65.2%) in group A were weaned from temporary RVAD support and three (6.5%) underwent permanent RVAD (HeartWare, Inc., Framingham, MA, USA) placement. A total of 26 patients (56.5%) were discharged home in group A versus 17 (54.8%) in group B (P = 0.56). Three patients (8.5%) received heart transplantation in group A and six (19.3%) in group B (P = 0.04). In group A, 90-day and 6-month survival was 54.3% (n = 25) versus 51.6% (n = 16) in group B (P = 0.66). In group A, 1-year survival was 45.6% (n = 21) versus 45.1% (n = 14) in group B (P = 0.81). The strategy of planned temporary RVAD support in LVAD recipients showed encouraging results if compared with those of a similar permanent BVAD/TAH population. Weaning from and removal of the temporary RVAD support may allow patients to be on LVAD support only despite preoperative biventricular dysfunction.

Evaluation of the HeartWare HVAD centrifugal pump for right ventricular assistance in an in vitro model.

We have developed a method that allows the use of a commercially available implantable left ventricular assist device (LVAD; HeartWare HVAD) for right ventricular (RV) assistance. A mock circulation was used to examine the flow characteristics of the system with different outflow diameters (10–4 mm). Furthermore, we looked for a material for safe and satisfactory reduction of the effective length of the inflow cannula for better fitting to the RV dimensions. Reduction of the outflow graft to an inner diameter of ∼5 mm adds as much resistance to the system that in patients with a normal pulmonary resistance, the pump would deliver between 3.5 and 7 L/min. We added two 5 mm silicon suture rings to the systems “apical” sewing ring to reduce the effective length of the inflow cannula. Connection of the pump to the anterior free wall of the right ventricle ensures good orientation of the inflow cannula within the RV cavity, with sufficient space to prevent the inflow cannula from suction to the opposite interventricular septum. The HeartWare LVAD pump seems also to be usable as a right ventricular assist device (RVAD) after a few, but important, modifications of the implant procedure.

Tricuspid Valve Repair in Patients Supported with Left Ventricular Assist Devices

In patients with end-stage heart failure, severe tricuspid regurgitation (TR) might be one of the signs of biventricular failure with subsequent need for biventricular support (biventricular assist device [BVAD]) or total artificial heart (TAH). However, tricuspid valve repair (TVR) may avoid BVAD or TAH implantation. Consecutive patients with TR of grade 3+ receiving either left ventricular assist device with concomitant TVR (group A, n = 7) or a BVAD/TAH (group B, n = 18) implanted in our institution between 2007 and 2010 were compared retrospectively. Intermacs (Interagency Registry for Mechanically Assisted Circulatory Support) stage I, age less than 18 years, and postcardiotomy failure were the exclusion criteria. Preoperative parameters were similar in both groups. No differences in 30-day mortality (28.5% vs. 22.2%, p = 0.8), postoperative dialysis, intensive care unit (ICU) stay (35 vs. 22 days, p = 0.94), or ventilation time (15 vs. 13 days) were seen. Timing of discharge home was similar in both groups (42.8% after a median of 45 days vs. 50% after a median of 40 days [p = 0.78]). Six months after surgery, no significant TR was seen in group A. Right ventricular failure requiring mechanical support occurred in 14.2% (n = 1) in group A. In patients with TR of grade 3+, left ventricular assist device support combined with TVR showed comparable results with biventricular support with regard to short-term outcome. These results led to a change of our established ventricular assist device implantation strategy.

The impact of overweight on the development of diabetes after heart transplantation.

Abstract:  Background:  Overweight is defined with a body mass index (BMI) >25. A BMI >25 is known as an independent risk factor for increased morbidity and mortality. The influence of an increased BMI on the development of diabetes and on survival after heart transplantation (HTX) was investigated.

Discontinuation of HeartWare RVAD support without device removal in chronic BIVAD patients.

During biventricular assist device (BVAD) support, right ventricular (RV) assistance may restore sufficient RV function after several weeks to months. Since November 2009, 10 patients (9 men and 1 woman; mean age, 49.7 ± 14.4 y) suffering from idiopathic dilatative cardiomyopathy received BVAD employing two implantable continuous-flow pumps of the HeartWare type. In three male patients, aged 53, 57, and 60 years, after a right ventricular assist device (RVAD) support time of 15.6, 11.2, and 3.6 months, respectively, the RVAD was stopped, and the percutaneous lead was surgically shortened in two cases. There were no differences in preoperative RV geometry and function or in severity of tricuspid valve regurgitation in patients with and without delayed RV recovery. Follow-up echocardiography revealed no regurgitation through the right pump in any patient. One patient died due to severe sepsis 63 days later; the other two patients are currently on left ventricular assist devices support at home, 120 and 236 days after RVAD deactivation with stable hemodynamic conditions and without any thromboembolic events. RV function may recover even after weeks or months on BVAD support. The HeartWare HVAD used as an RVAD may be stopped and left in place without complications.