DeBakey Ventricular Assist Device Research Articles

Thromboresistance Comparison of the HeartMate II Ventricular Assist Device With the Device Thrombogenicity Emulation-Optimized HeartAssist 5 VAD

Approximately 7.5 × 106 patients in the US currently suffer from end-stage heart failure. The FDA has recently approved the designations of the Thoratec HeartMate II ventricular assist device (VAD) for both bridge-to-transplant and destination therapy (DT) due to its mechanical durability and improved hemodynamics. However, incidence of pump thrombosis and thromboembolic events remains high, and the life-long complex pharmacological regimens are mandatory in its VAD recipients. We have previously successfully applied our device thrombogenicity emulation (DTE) methodology for optimizing device thromboresistance to the Micromed Debakey VAD, and demonstrated that optimizing device features implicated in exposing blood to elevated shear stresses and exposure times significantly reduces shear-induced platelet activation and significantly improves the device thromboresistance. In the present study, we compared the thrombogenicity of the FDA-approved HeartMate II VAD with the DTE-optimized Debakey VAD (now labeled HeartAssist 5). With quantitative probability density functions of the stress accumulation along large number of platelet trajectories within each device which were extracted from numerical flow simulations in each device, and through measurements of platelet activation rates in recirculation flow loops, we specifically show that: (a) Platelets flowing through the HeartAssist 5 are exposed to significantly lower stress accumulation that lead to platelet activation than the HeartMate II, especially at the impeller-shroud gap regions (b) Thrombus formation patterns observed in the HeartMate II are absent in the HeartAssist 5 (c) Platelet activation rates (PAR) measured in vitro with the VADs mounted in recirculation flow-loops show a 2.5-fold significantly higher PAR value for the HeartMate II. This head to head thrombogenic performance comparative study of the two VADs, one optimized with the DTE methodology and one FDA-approved, demonstrates the efficacy of the DTE methodology for drastically reducing the device thrombogenic potential, validating the need for a robust in silico/in vitro optimization methodology for improving cardiovascular devices thromboresistance.

Comparative efficacy of in vitro and in vivo metabolized aspirin in the DeBakey ventricular assist device

Ventricular assist devices (VADs) are implanted in patients with end-stage heart failure to provide both short- and long-term hemodynamic support. Unfortunately, bleeding and thromboembolic complications due to the severely disturbed, dynamic flow conditions generated within these devices require complex, long-term antiplatelet and anticoagulant therapy. While several studies have examined the effectiveness of one such agent, aspirin, under flow conditions, data comparing the efficacy of in vitro and in vivo metabolized aspirin is lacking. Two sets of studies were conducted in vitro with purified human platelets circulating for 30min in a flow loop containing the DeBakey VAD (MicroMed Cardiovascular, Houston, TX, USA): (a) 20μM aspirin was added exogenously in vitro to platelets isolated from aspirin-free subjects, and (b) platelets were obtained from donors 2h (n=14) and 20h (n=13) after ingestion of 1,000mg aspirin. Near real-time platelet activation state (PAS) was measured with a modified prothrombinase-based assay. Platelets exposed to aspirin in vitro and in vivo (metabolized) showed 28.2 and 25.3% reduction in platelet activation rate, respectively, compared to untreated controls. Our results demonstrate that in vitro treatment with antiplatelet drugs such as aspirin is as effective as in vivo metabolized aspirin in testing the effect of reducing shear-induced platelet activation in the VAD. Using the PAS assay provides a practical in vitro alternative to in vivo testing of antiplatelet efficacy, as well as for testing the thrombogenic performance of devices during their research and development.

Interactive Blood Damage Analysis for Ventricular Assist Devices

Ventricular Assist Devices (VADs) support the heart in its vital task of maintaining circulation in the human body when the heart alone is not able to maintain a sufficient flow rate due to illness or degenerative diseases. However, the engineering of these devices is a highly demanding task. Advanced modeling methods and computer simulations allow the investigation of the fluid flow inside such a device and in particular of potential blood damage. In this paper we present a set of visualization methods which have been designed to specifically support the analysis of a tensor-based blood damage prediction model. This model is based on the tracing of particles through the VAD, for each of which the cumulative blood damage can be computed. The model's tensor output approximates a single blood cell's deformation in the flow field. The tensor and derived scalar data are subsequently visualized using techniques based on icons, particle visualization, and function plotting. All these techniques are accessible through a Virtual Reality-based user interface, which features not only stereoscopic rendering but also natural interaction with the complex three-dimensional data. To illustrate the effectiveness of these visualization methods, we present the results of an analysis session that was performed by domain experts for a specific data set for the MicroMed DeBakey VAD.

Off-pump Exchange of Short-term Percutaneous Ventricular Assist Device (VAD) to Long-term Implantable VAD in Severe Coagulopathy and Multi-organ Failure

Ventricular support in patients with end-stage heart failure can be achieved using intracorporeal left ventricular assist device (LVAD) or percutaneous ventricular assist device (pVAD) systems. Multiple efforts have been made to minimize procedure-associated complications. We present a case report of an off-pump insertion of a MicroMed DeBakey VAD after Tandem Heart support using a previous sternotomy incision. A 47-year-old woman with end-stage heart failure after coronary artery bypass graft revascularization was admitted for pharmacologic treatment. She developed multi-organ failure and a severe coagulopathy with thromboembolic complications. Heparin-induced thrombocytopenia (HIT) was suspected. A percutaneous Tandem Heart was placed, the patient's condition stabilized, and finally a MicroMed DeBakey Child VAD was implanted off-pump, re-opening a previous sternotomy incision. To avoid the need for heparinization in the light of HIT and severe coagulopathy, the LVAD implantation was performed under Tandem Heart support without cardiopulmonary bypass. The patient has been anti-coagulated with angiomax ever since. Critically ill patients with end-stage heart disease, multi-organ failure, severe coagulopathy and a previous median sternotomy can be bridged from a Tandem Heart to MicroMed DeBakey VAD without cardiopulmonary bypass using the previous incision, provided there are few adhesions and stable hemodynamic conditions.

Invited commentary

Invited commentary

Bridge to Transplant Using the MicroMed DeBakey Ventricular Assist Device in a Child with Idiopathic Dilated Cardiomyopathy

We report the implantation of the MicroMed DeBakey left ventricular assist device (MDBVAD) in a 10-year-old girl with cardiogenic shock secondary to an idiopathic dilated cardiomyopathy. This was the first pediatric implant of the MDBVAD in the United States and the youngest patient worldwide. The patient recovered well and subsequently underwent successful heart transplantation after 84 days of support.

Bridge to transplantation with the MicroMed DeBakey ventricular assist device axial pump: a single centre report

Left ventricular assist devices (VADs) are an accepted therapy to bridge patients with end-stage heart failure to heart transplantation. The DeBakey VAD, a continuous axial flow pump weighing 93 g, has been introduced into clinical practice as a bridge to transplant. Starting from April 2000,17 patients (12 males, five females, mean age 44.3 +/- 12.8 years; 11 dilated idiopathic cardiomyopathy, five ischaemic cardiomyopathy, one pulsatile device failure) with end-stage heart failure were implanted with a DeBakey VAD as a bridge to transplantation at our institution. Before implant, all patients suffered from severe heart failure (New York Heart Association functional class IV) despite optimal medical therapy and were put on the waiting list for heart transplantation. Mean cardiac index was 1.59 +/- 0.51 l/min/m2. Fourteen patients were successfully transplanted after 99 +/- 117 days of assistance (range 11-443 days). Two patients died during assistance of multiorgan failure, one patient is still on VAD. No patient needed additional right ventricular mechanical support. Left ventricular/left VAD thrombosis occurred in one patient who was successfully treated conservatively. No clinical elevation of plasma free haemoglobin was detected. Neither device, driveline, abdominal pocket infection nor device failure occurred. In our experience with the continuous axial flow DeBakey VAD, a high success rate was obtained associated with a low risk of complications. All the patients tolerated continuous blood flow for extended periods that makes this device a valuable alternative to pulsatile VADs as a bridge to transplantation.

Human Leukocyte Antigen Sensitization in Ventricular Assist Device Recipients: A Lesser Risk With the DeBakey Axial Pump

Previous reports, all concerning pulsatile devices, have indicated an increased risk of development of circulating antileukocyte antigen (HLA; human leukocyte antigen) antibodies during ventricular assist device (VAD) support. We investigated sensitization in patients implanted with the DeBakey VAD (MicroMed Technology, Inc, Houston, TX) axial flow pump as a bridge to heart transplantation. Inclusion criteria for this prospective study were the following. Patients implanted with the DeBakey VAD axial flow pump, without HLA antibodies prior to implantation, with a duration of support of at least one month. The HLA antibody testing for IgG and IgM class I and II antibodies was performed weekly during support, using both a complement dependant cytotoxicity assay and an enzyme-linked immunosorbent assay (ELISA). Retrospective cross match was performed for all patients transplanted. The occurrence of graft rejection was determined by regular endomyocardial biopsies after heart transplantation, graded according to the International Society for Heart and Lung Transplantation (ISHLT) guidelines. Additionally, the transfusion history was reviewed for all patients. Fourteen patients were included representing 1,220 cumulative patient-days of support (mean duration time on support, 87 days). No patient developed detectable IgG antibodies to class I or II. One patient had a positive ELISA, corresponding to nonsignificant (6/30) class I IgM antibodies at 3 weeks postimplantation. Ten patients underwent successful heart transplantation, representing 156 cumulative months. No retrospective cross match was positive. The percentage of significant acute rejection episodes (ISHLT grade 3A or more) was 6% and 4.3% in the first 6 months and from 6 to 12 months, respectively. No vascular rejection was noted. The posttransplantation survival rate was 87% at 6 months and 75% at 1 year, respectively. Patients implanted with the DeBakey VAD axial flow pump as a bridge to heart transplantation do not appear to be exposed to an increased risk of sensitization.

Suction Detection for the MicroMed DeBakey Left Ventricular Assist Device

The MicroMed DeBakey Ventricular Assist Device (MicroMed Technology, Inc., Houston, TX) is a continuous axial flow pump designed for long-term circulatory support. The system received CE approval in 2001 as a bridge to transplantation and in 2004 as an alternative to transplantation. Low volume in the left ventricle or immoderate pump speed may cause ventricular collapse due to excessive suction. Suction causes decreased flow and may result in patient discomfort. Therefore, detection of this critical condition and immediate adaptive control of the device is desired. The purpose of this study is to evaluate and validate system parameters suitable for the reliable detection of suction. In vitro studies have been performed with a mock loop allowing pulsatile and nonpulsatile flow. Evidence of suction is clearly shown by the flow waveform reported by the implanted flow probe of the system. For redundancy to the implanted flow probe, it would be desirable to use the electronic motor signals of the pump for suction detection. The continuously accessible signals are motor current consumption and rotor/impeller speed. The influence of suction on these parameters has been investigated over a wide range of hydrodynamic conditions, and the significance of the respective signals individually or in combination has been explored. The reference signal for this analysis was the flow waveform of the ultrasonic probe. To achieve high reliability under both pulsatile and nonpulsatile conditions, it was determined that motor speed and current should be used concurrently for suction detection. Using the amplified differentiated current and speed signals, a suction-detection algorithm has been optimized, taking into account two different working points, defined by the value of the current input. The safety of this algorithm has been proven in vitro under pulsatile and nonpulsatile conditions over the full spectrum of possible speed and differential pressure variations. The algorithm described herein may be best utilized to provide redundancy to the existing flow based algorithm.

Lessons learned from the first application of the DeBakey VAD Child: An intracorporeal ventricular assist device for children

We report and describe the design and the first clinical implantation of the DeBakey ventricular assist device (VAD) Child, a pediatric intracorporeal left ventricular assist device, in a 6-year-old girl. The risk-benefit of novel technologies in advanced heart failure and the lessons learned by our experience are important to consider in hopes that other centers (where this device is now available) may benefit.

Successful replacement of malfunctioning TCI HeartMate LVAD with DeBakey LVAD as a bridge to heart transplantation

Congestive heart failure is the leading cause of hospitalization and death in the developed world and affects about 0.4-2% of the adult population [Ann Thorac Surg 1999;68:637-40]. Heart transplantation remains the most effective therapy for end-stage heart disease, but the shortage of donors has led to increasing interest in other surgical options, especially ventricular assist devices (VAD). Several VADs are available to bridge patients to transplantation [N Engl J Med 2001;345:1435-43], including pulsatile devices like the HeartMate (HeartMate, Thoratec, Pleasanton, CA) and Novacor (World Heart, Netherlands), and the DeBakey VAD (MicroMed Technology, Inc., Houston, TX), which is an electromagnetically driven implantable titanium axial flow blood pump designed for left ventricular support. Despite technical improvements, VADs still are associated with serious complications. We reporte a successfull case where we replaced a TCI HeartMate with a DeBakey VAD because of a serious pocket infection, deterioration and failure of the inflow valve.

Extensive Coagulation Monitoring in Patients After Implantation of the MicroMed Debakey Continuous Flow Axial Pump

Ventricular assist device (VAD) implantation is associated with impaired primary hemostasis and thromboembolic complications. Recently, a new generation of implantable continuous flow axial pumps was introduced into clinical application. To study the potential thrombogenic properties of this type of pump, we applied extensive platelet monitoring was applied. In our institution, 13 patients received the MicroMed DeBakey VAD as a bridge to transplantation. Routine coagulation tests (platelet count, activated partial thromboplastin time, prothrombin time, antithrombin III activity) and platelet function tests (whole blood aggregometry, thrombelastography, flow cytometry) were performed. No clinically relevant thromboembolic events were detected. No correlation was found between global function tests, platelet aggregation, and thrombelastography. No correlation was detected between platelet activation and hemolysis parameters. Platelet aggregation and coagulation index were significantly suppressed early after operation. A subsequent phase of hyper-aggregability, starting around day 6, suggested the initiation of antiaggregation therapy. Platelet activation markers were upregulated in the postoperative period but were returned to preoperative levels after initiation of aspirin. In contrast to routine coagulation monitoring, platelet function tests reflect in detail the coagulation status of blood pump recipients and the efficiency of antiaggregation therapy. Aspirin and dipyridamole therapy in addition to oral anticoagulation using phenprocoumon may contribute to platelet function and clot mechanics restoration and is, therefore, recommended for patients after VAD implantation.

Invited commentary

Background. Although bleeding and thromboembolism remain major complications after implantation of ventricular assist devices (VADs), no standard anticoagulation protocols are available. Genetic polymorphism of platelet glycoprotein IIb/IIIa may contribute to the development of complications. The present study demonstrates a relationship between the PIA genotype and postoperative complications in patients implanted with pulsatile and axial flow VADs. Methods. The P1A genotype was determined in 41 consecutive patients treated with a VAD who received anticoagulation with phenprocoumon and aspirin. Pulsatile Novacor (Novacor Corp, Oakland, CA) and Berlin Heart VADs (Berlin Heart, Berlin, Germany) were implanted in 28 patients and the axial flow MicroMed DeBakey VAD (MicroMed Technology, Inc, Houston, TX) in 13. The relationship between the P1A genotype, the anticoagulation regime, and bleeding and thromboembolic events was analyzed. Results. There were no differences between patients with the A1A1 and A1A2 genotype regarding demographic characteristics, weight, or infection episodes. The international normalized ratio (INR), platelet activation tests, and doses of aspirin and dipyridamol before events were similar in both groups. Patients with the A1A1 genotype developed more bleeding complications (39% vs 0%, p = 0.021), while patients with the A1A2 genotype showed a tendency toward more thromboembolic events (13% vs 30%, p = 0.33). With regard to different types of VAD, patients with the axial flow DeBakey VAD and the A1A1 genotype developed significantly more bleeding complications (70% vs 0%, p = 0.033). Conclusions. In patients with a long-term VAD determination of P1A polymorphism and subsequent adjustment of the anticoagulation regime may lead to a reduction of bleeding and thromboembolic complications.

Clinical significance of PlA polymorphism of platelet GP IIb/IIIa receptors during long-term VAD support

Background Although bleeding and thromboembolism remain major complications after implantation of ventricular assist devices (VADs), no standard anticoagulation protocols are available. Genetic polymorphism of platelet glycoprotein IIb/IIIa may contribute to the development of complications. The present study demonstrates a relationship between the PlA genotype and postoperative complications in patients implanted with pulsatile and axial flow VADs. Methods The PlA genotype was determined in 41 consecutive patients treated with a VAD who received anticoagulation with phenprocoumon and aspirin. Pulsatile Novacor (Novacor Corp, Oakland, CA) and Berlin Heart VADs (Berlin Heart, Berlin, Germany) were implanted in 28 patients and the axial flow MicroMed DeBakey VAD (MicroMed Technology, Inc, Houston, TX) in 13. The relationship between the PlA genotype, the anticoagulation regime, and bleeding and thromboembolic events was analyzed. Results There were no differences between patients with the A1A1 and A1A2 genotype regarding demographic characteristics, weight, or infection episodes. The international normalized ratio (INR), platelet activation tests, and doses of aspirin and dipyridamol before events were similar in both groups. Patients with the A1A1 genotype developed more bleeding complications (39% vs 0%, p = 0.021), while patients with the A1A2 genotype showed a tendency toward more thromboembolic events (13% vs 30%, p = 0.33). With regard to different types of VAD, patients with the axial flow DeBakey VAD and the A1A1 genotype developed significantly more bleeding complications (70% vs 0%, p = 0.033). Conclusions In patients with a long-term VAD determination of PlA polymorphism and subsequent adjustment of the anticoagulation regime may lead to a reduction of bleeding and thromboembolic complications.

Transistory immunologic response after implantation of Debakey VAD continous-axial-flow-pump

Background: The development of local systemic infection is a significant risk factor associated with ventricular assist device (VAD) implantation. The immunological consequences of continous-flow rotary blood pumps is not known. Methods: 6 male adult patients (mean age 47 /10.3) suffering from end-stage left heart failure were implanted with DeBakey VAD axial-flow pump for the use as bridge to tranplantation ( 4 patients were transplanted after a mean 115 /14 days, 2 patients are still waiting for the allograft). We prospectively monitored T-cell populations and apoptosis specific aberrant T-cell activation via CD95 triggering and annexin V binding to lymphocytes (FACS analysis), identifying T cells undergoing early phases of apoptosis, within the first 10 weeks. Moreover soluble death inducing receptors (DIR) sCD95, sTNF-R1 were evaluated by ELISA. Results: Patients bridged by non-pulsatile VAD to transplantation demonstrate a initial pronounced apoptosis specific immunealteration as demonstrated by increased annexin V binding to CD3 positive T cells (prior implantation 18 /8.5 %, 4th week 41.4 /9.3%, 7th week 10.8 /3%) and DIR sCD95 (1.32 /0.21ng, 7.6 /4.2ng, 0.9 /0.7ng), sTNF-R1 (1.5 /0.23ng, 10 /6.9ng, 2.1 /0.8ng) (all p 0.001). All parameters normalized after 7 weeks to baseline. No blood born sepsis was detected, as defined by blood culture, within the first 10 weeks of the study cohort. Conclusions: These results indicate a biphasic immunologic response in patients suffering of end-stage heart failure patients treated with non-pulsatile ventricular assist devices.

Complications common to ventricular assist device support are rare with 90 days of DeBakey VAD support in calves.

The DeBakey VAD is a miniaturized, electromagnetically driven axial flow pump intended for long-term ventricular assist. Safety and performance data from six calves implanted with the complete DeBakey VAD system are reported elsewhere; here we describe complications and necropsy findings for these same six animals, all of which survived 90 days. The study was conducted according to a uniform protocol, which included anticoagulation and antibiotic prophylaxis. Clinical complications tracked included bleeding, cardiovascular abnormalities (e.g., arrhythmias, tachycardia unrelated to pain, bradycardia), hemolysis, hepatic dysfunction, renal dysfunction, thromboembolism (neurologic or peripheral), or infection. Each adverse event was retrospectively categorized with regard to severity (mild, moderate, severe) and relationship to device. Clinical findings were confirmed by necropsy. There was no evidence of systemic infection, thromboembolism, hemolysis, or renal or hepatic dysfunction in these six animals during the study period. A single adverse event was noted in each of two of the calves. Both events were considered mild according to the predefined criteria. Bleeding related to the surgical implantation procedure and requiring reoperation occurred in one animal. The other animal had evidence of a superficial infection at the exit site of the cables on the left lateral thoracic wall; the infection did not extend into the thoracic cavity. Chronic, healed small renal infarct scars were present in several animals. Mild valvular endocardiosis was observed in two calves and mild fibroelastosis was present in the endocardium at the site of the inflow cannula in three calves; however, these lesions were not considered clinically significant. No other gross or histologic abnormalities were noted at necropsy. In conclusion, calves implanted with the complete DeBakey VAD for 90 days demonstrated few complications and had no significant necropsy findings. Complications common to ventricular assist device (VAD) support (i.e., hemolysis, infection, bleeding, thromboembolism) were rare during long-term support (90 days) with the DeBakey VAD.

Lessons learned from the first clinical implants of the DeBakey ventricular assist device axial pump: a single center report

Background. The bridge to transplantation with pulsatile mechanical assist devices became a standard procedure for patients deteriorating on the waiting list. Recently, continuous flow axial impeller pumps were introduced to clinical application offering new advantages. Methods. From November 1998 till September 2000, 6 male patients (mean age 53 plus or minus 11 years) with end-stage left heart failure were implanted with a DeBakey ventricular assist device (VAD) axial-flow pump for bridge to transplantation. Results. Three patients were successfully transplanted after 74, 115, and 117 days, respectively. Two other patients died after 25 and 133 days. One patient is still on the device after 108 days. Because of modification of the implantation technique after the first 2 patients, mean pump-flow within the first 3 weeks was increased from 4.3 ± 0.6 L/min to 6.7 ± 0.3 L/min. Patients were put on regular bicycle-ergometer training and improved their exercise capacities up to a mean maximum oxygen consumption of 20.2 mL/kg/min. Conclusions. Initial implants of the DeBakey VAD demonstrated support properties comparable to pulsatile pumps but without significant restrictions for extended use.

Clinical experience with the MicroMed DeBakey ventricular assist device

Background. The MicroMed DeBakey ventricular assist device (VAD) (MicroMed Technology, Inc, Houston, TX) is the first long-term axial flow circulatory assist device to be introduced into clinical trials as a bridge to transplantation. Clinical trials began in Europe in November 1998 and in the United States in June 2000. Methods. To qualify for the study, the patients must be listed for cardiac transplantation and must have demonstrated profound cardiac failure. There were no exclusions to the MicroMed DeBakey VAD implant other than those patients who would typically be excluded from cardiac transplantation. Results. As of September 2000, 51 patients have been implanted with the MicroMed DeBakey VAD. A detailed evaluation of the first 32 patients has been completed. With current data, the probability of survival at 30 days after VAD implant is 81%. Conclusions. The clinical trial demonstrated that the MicroMed DeBakey VAD is capable of providing adequate circulatory support in patients with severe heart failure, sufficient to recover and return to normal activities while awaiting a heart transplantation. Much has been learned about the function of the device and its continuous flow in humans.

Pulsatile Flow in Patients With a Novel Nonpulsatile Implantable Ventricular Assist Device

Background —Ventricular assist devices (VADs) are an accepted therapy for patients with end-stage heart failure. The implantable devices that are available produce a pulsatile flow and are very large. In 6 patients, beginning in November 1998, we started to use the continuous-flow implantable DeBakey VAD device, which weighs 93 g. To detect the flow in peripheral vessels, we measured transcranial Doppler signals in patients after implantation. Methods and Results —Transcranial Doppler studies were performed with the MULTI-DOP X4 device with two 2-MHz probes (for the middle cranial arteries) in 4 patients for up to 12 weeks twice weekly after implantation. The blood velocity was measured, and the pulsation index (PI) calculated. The measured pump flow and rotations per minute were registered. The preoperative echocardiographic assessment values were compared with those acquired 6 weeks after implantation. The PI increased continually in all patients after VAD implantation, left ventricular (LV) ejection fraction did not improve, but right ventricular (RV) ejection fraction after implantation improved compared with preoperative values. The LV end-diastolic diameter after implantation decreased between 11% and 46% intraindividually. There was no correlation between PI and blood pressure or, except in 1 patient, between PI and blood flow through the VAD. Conclusions —The DeBakey VAD unloads the LV, which leads to a decrease in LV end-diastolic LV diameter and to the restoration of RV function. The unloaded LV and partially recovered RV provide a nearly physiological pulsatile flow despite the continuous flow of the VAD. Pulsatility is independent of peripheral vascular resistance. The first clinical experience with the DeBakey VAD was positive and has resulted in its continued use.

Development and clinical application of the MicroMed DeBakey VAD.

A miniaturized axial flow pump to provide left ventricular assistance has been developed. Such a device has the potential to address limitations of the larger pulsatile devices. Clinical trials of the MicroMed DeBakey VAD (ventricular assist device) began in Europe in November 1998. As of December 1, 1999, 18 patients have been implanted with the MicroMed DeBakey VAD. Hemodynamic evaluations along with blood chemistry analysis were recorded routinely. Exercise tolerance was observed. In most patients, end-organ function has improved and has not deteriorated in any patient. Patients have been able to perform normal low-level activity and have tolerated positional changes without evidence of postural hemodynamic changes. Select patients have taken supervised out-of-hospital excursions. This initial clinical experience with the MicroMed DeBakey VAD suggests that the miniaturized axial flow pump can provide ventricular support to bridge patients to cardiac transplant and may provide an improved quality of life for the end-stage heart failure recipient.