A reliable bridge to cardiac transplantation: the TCI left ventricular assist device

Ventricular-assist devices for the treatment of chronic heart failure

The role of ventricular-assist devices in the management of end-stage heart failure is growing. Initially developed as a 'bridge to transplantation', they are now implanted permanently in patients who need cardiac replacement but are not candidates for cardiac transplantation ('destination therapy'). Furthermore, observations from expert centers indicate that a significant proportion of patients under long-term mechanical assistance can be weaned from mechanical circulatory support after significant functional recovery of their native heart ('bridge to recovery'). This review discusses the emerging roles of mechanical circulatory support and their direct implications in clinical practice. Evolution of devices, important aspects of candidate selection, challenging issues in the management of ventricular-assist device patients (infection, device malfunction, anticoagulation-thromboembolic complications, psychosocial issues and cost) and ongoing research targeting sustained myocardial recovery are discussed.

The treatment of an unusual complication associated with a HeartMate II LVAD in an adolescent

The HeartMate II LVAD has provided a bridge to heart transplantation or a permanent fixture for destination therapy for patients with heart failure. LVAD infections are associated with significant morbidity even when treated with explantation, device exchange, or a salvage procedure. We present an unusual complication following the placement of the HeartMate II device in an adolescent, whereby a pocket infection resulted in a large soft tissue defect overlying and surrounding the device. The novel use of a VRAM flap was successfully used to repair the defect and salvage the device.

The Status of Failure and Reliability Testing of Artificial Blood Pumps

Artificial blood pumps are today's most promising bridge-to-transplant, bridge-to-recovery, and destination therapy solutions for patients with congestive heart failure. There is a critical need for increased reliability and safety as the next generation of artificial blood pumps approach final development for long-term destination therapy. To date, extensive failure and reliability studies of these devices are considered intellectual property and thus remain unpublished. Presently, the Novacor N100PC, Thoratec VAD, and HeartMate LVAS (IP and XVE) comprise the only four artificial blood pumps commercially available for the treatment of congestive heart failure in the United States. The CardioWest TAH recently received premarket approval from the US Food and Drug Administration. With investigational device exemptions, the AB-180, AbioCor, LionHeart, DeBakey, and Flowmaker are approved for clinical testing. Other blood pumps, such as the American BioMed-Baylor TAH, CorAide, Cleveland Clinic-Nimbus TAH, HeartMate III, Hemadyne, and MagScrew TAH are currently in various stages of mock loop and animal testing, as indicated in published literature. This article extensively reviews in vitro testing, in vivo testing, and the early clinical testing of artificial blood pumps in the United States, as it relates to failure and reliability. This detailed literature review has not been published before and provides a thorough documentation of available data and testing procedures regarding failure and reliability of these various pumps.

Bridge to transplant with the HeartMate device

The incidence and prevalence of chronic heart failure continues to increase, with an estimated 400,000 new cases per year in the United States. Cardiac transplantation is an effective therapy but is severely limited to approximately 2300 patients per year due to the donor shortage. With ever increasing waiting times, a significant number of patients become severely debilitated or expire prior to transplantation. A mechanical circulatory support device was first used as a "bridge to transplantation" in 1969. Since then, mechanical devices have increased tremendously in reliability and efficaciousness. The HeartMate left ventricular assist device (LVAD) has been utilized extensively in a bridge to transplant application with excellent results. Patients refractory to aggressive medical management can be sustained reliably until transplantation. In addition, bridging allows for the correction of physiologic and metabolic dearrangements often seen in these severely ill patients prior to transplantation. Nutritional, economic, and quality-of-life issues also favor earlier LVAD placement in refractory patients. This reportsummarizes the overall bridging experience with the HeartMate LVAD and focuses on our experience with this device at Rush-Presbyterian-St. Luke's Medical Center.

Left ventricular assist device infections: three case reports and a review of the literature

Left ventricular assist device (LVAD) infections are a major device complication and are associated with significant morbidity. We report three cases of LVAD infections in our institution and review the literature to assess clinical parameters associated with infection, causative organisms, treatment modalities, and patient outcomes. A total of 46 cases were reviewed. Fever, leukocytosis, and drainage from the exit site were the most commonly reported symptoms. Left ventricular assist devices were in place an average of 65 days before the onset of infection. The most common site of LVAD infection was the drive line. Staphylococcus aureus was the most common organism, followed by gram negative rods, Candida, and enterococcus species and coagulase negative Staphylococcus. Treatment consisted primarily of surgical intervention, including incisional debridement, pump pocket exploration, and LVAD replacement and adjunctive intravenous antibiotics, especially vancomycin. Only eight infected patients died before transplantation, with five deaths due to sepsis. Four of these five patients were infected with a gram negative rod. In general, patients who developed an LVAD infection were able to undergo successful transplantation without recurrence, but infection with a gram negative rod was associated with a poor outcome.

The use of muscle flaps to treat left ventricular assist device infections

Left ventricular assist devices have become an important adjunct in the therapeutic armamentarium for patients with end-stage heart failure. Although they may provide a bridge to transplantation, they are prone to certain problems, expecially infection. Because these are life-sustaining devices, changing the device or simple explantation may be a risky, if not impossible, option. Therefore, we evaluated the effectiveness of a surgical alternative, namely, coverage of infected devices with muscle or myocutaneous flaps. Eighty-two consecutive patients who underwent the insertion of 88 left ventricular assist devices at our institution over a 6.5-year period were evaluated. Follow-up was provided for all patients and ranged from 1 to 7.5 years. The duration of ventricular support ranged from 0 to 434 days. All patients who demonstrated clinical evidence of infection were identified. Overall, 54 patients (66 percent) had infections locally at the device site, at distant sites, or systemically during support. Cultured organisms included gram-positive and -negative bacteria, fungi, and viruses. Of the 56 infections in these 54 patients, 21 (38 percent) were device-related, i.e., in the pocket created by the device, in the device itself, or from the driveline. Thus, 24 percent (21 of 88) of all ventricular support devices inserted demonstrated device infection during use. Therapeutic modalities used to combat device-related infection included both nonsurgical management with antibiotics alone and surgical procedures such as device change or relocation, device explant, and flap coverage. Eight of the 20 patients in whom the 21 device-related infections occurred underwent surgical intervention. Four of these eight patients undenwent local flap coverage of their infected left ventricular assist devices. All four patients also had evidence of systemic infection, or "device endocarditis." Coverage was successfully achieved in all cases with pedicled rectus abdominis flaps. There were no perioperative complications. Two patients later underwent successful transplantation; the other two died from causes unrelated to the flap. In conclusion, the treatment of infected left ventricular assist devices currently includes both nonsurgical and surgical alternatives. Of the latter, muscle flaps should be considered a first-line intervention to assist in eradicating infection by providing well-vascularized tissue. Although there were no perioperative complications, the 50 percent mortality rate is consistent with that reported for patients with "device endocarditis." It may be that flap coverage of infected ventricular assist devices, if instituted at an earlier stage in the therapeutic process, could help prevent systemic infection in these patients and, therefore, improve their overall outcome.

Left ventricular assist device implantation: short and long-term surgical complications

Long-term implanted left ventricular assist devices (LVADs) have significantly improved the care of patients awaiting heart transplantation and will provide an alternative therapy to select patients with heart failure. However, although the technology and clinical results continue to improve, LVAD implantation is still associated with a significant level of complications. Left ventricular assist device-associated complications can be broadly divided by their temporal occurrence. Early complications include perioperative hemorrhage, air embolism, and right ventricular failure. Beyond the perioperative period, late complications consist primarily of infection, thromboembolism, and primary device failure. An improved understanding of the mechanisms involved should aid the clinician in further reducing the incidence of these occurrences.

Comparison of functional capacity in patients with end-stage heart failure following implantation of a left ventricular assist device versus heart transplantation: results of the experience with left ventricular assist device with exercise trial

BACKGROUND

Use of a permanent left ventricular assist device (LVAD) has been proposed as an alternate treatment of patients with end-stage heart failure. The purpose of this study was to compare the functional capacity of patients following implantation of a LVAD vs heart transplant (HTx).

METHODS

Eighteen patients from 6 centers who received an intracorporeal LVAD as a bridge to HTx underwent treadmill testing 1 to 3 months post-LVAD and again post-HTx. Baseline and peak measurements, including oxygen consumption, blood pressures, and respiratory rate were made during each treadmill test.

RESULTS

Peak oxygen consumption was 14.5+/-3.9 ml/kg/minute post-LVAD and 17.5+/-5.0 ml/kg/minute post-HTx (p < .005). The percentage of the predicted peak oxygen consumption based on gender, weight, and age was 39.5%+/-5.5% post-LVAD and 47.7%+/-10.9% post-HTx (p < .005). Exercise duration was lower post-LVAD than post-HTx (10.3+/-4.2 minute vs 12.5+/-5.4 minute, p < .05). After LVAD implantation, peak total oxygen consumption correlated with peak LVAD rate and output. Eight patients reached an LVAD rate of 120 beats per minute (bpm) before the conclusion of exercise, the maximum rate for the outpatient electric device. The peak respiratory exchange ratio post-LVAD was 1.15+/-0.22 and post-HTx was 1.15+/-0.18, consistent with a good effort in both groups.

CONCLUSIONS

Patients demonstrated a lower functional capacity post-LVAD than post-HTx. For some patients functional capacity post-LVAD may be improved by a higher maximum LVAD rate and output.

Time-dependent cellular population of textured-surface left ventricular assist devices contributes to the development of a biphasic systemic procoagulant response

OBJECTIVE

Textured-surface left ventricular assist devices (LVAD) have been shown to enhance ventricular function and survival in patients with end-stage heart failure. Furthermore, we have described a procoagulant physiology in our LVAD population with sustained thrombin generation (elevated thrombin-antithrombin III complex and prothrombin fragment 1+2) and fibrinolysis (D-dimers), even up to 335 days after LVAD placement. To explain such sustained activation of coagulation, we speculated that the LVAD surface selectively adsorbed and promoted activation of circulating blood cells.

METHODS

In a prospective study of 20 patients with LVADs, we examined samples of peripheral blood as well as cells harvested from the surface of the LVADs at the time of their explantation for procoagulant proinflammatory markers.

RESULTS

Analysis of the cells populating the LVAD surface revealed the presence of pluripotent hematopoietic CD34(+) cells, as well as cells bearing monocyte (CD14)/macrophage (CD68) markers, which also expressed procoagulant tissue factor. Reverse transcriptase-polymerase chain reaction confirmed cellular activation on the LVAD surface, revealing transcripts for interleukin 1alpha, interleukin 2, and tumor necrosis factor alpha, in addition to vascular cell adhesion molecule-1 consistent with their capacity to continually recruit and activate circulating cells, thereby propagating their response. In the periphery, elevated levels of tissue factor were found in the plasma of patients with LVADs, along with enhanced procoagulant activity.

CONCLUSION

These observations suggest that the LVAD surface selectively absorbs and activates circulating hematopoietic precursor and monocytic cells, thereby creating a sustained prothrombotic and potentially proinflammatory systemic environment.

The ventricular assist device as a bridge to cardiac transplantation

Congestive heart failure is occurring in the United States at an increasing rate. Transplantation remains the treatment of choice for end-stage heart failure. Prolonged waiting time and decreased availability of suitable organs has increased the necessity for a device to act as a bridge to transplantation to keep patients alive during the waiting period. Ventricular assist devices have become an accepted and proven option for patients whose condition deteriorates to the point that waiting for an available donor organ is a mortal risk. With proper patient selection and timely device insertion, these patients can remain stable until a donor organ becomes available.

HeartMate left ventricular assist device as bridge to heart transplantation

BACKGROUND

Because of the limited supply of donor hearts, prospective recipients continue to die while on the waiting list for heart transplantation. Use of long-term mechanical circulatory support devices as a bridge to transplantation may reduce this mortality. However, with the present state of technology, continued clinical evaluation of the various long-term, mechanical circulatory support devices available is mandatory.

METHODS

Sixteen patients were bridged with the HeartMate left ventricular assist device (LVAD) to heart transplantation for New York Heart Association functional class IV cardiac failure. Twelve pneumatic and six electric devices were used. The mean cardiac index and the mean pulmonary vascular resistance of the patient cohort were 1.71 x min(-1) x m(-2) and 3.1 Wood units, respectively.

RESULTS

The mean LVAD support time per transplanted patient was 237 days, with a cumulative LVAD support time of about 7.2 years. Bleeding was the main operative and postoperative complication. Two patients suffered from neurologic complications and there were two major incidents of device malfunction. Twelve patients (75%) now have received a transplant, 3 (19%) are awaiting a transplant, and in 1 patient (6%), the device was explanted after spontaneous left ventricular recovery. Eleven of the 12 patients who received a transplant are alive and doing well. The HeartMate LVAD gave adequate circulatory support over extended periods of time and reversed the vital organ dysfunction. Since the start of the LVAD program, only 1 patient has died on our heart transplantation waiting list, compared to nine deaths in the 2 preceding years.

CONCLUSIONS

The HeartMate LVAD bridge to heart transplantation can be performed with low post-LVAD implantation and posttransplantation mortality and offers 1- and 2-year posttransplantation actuarial survival rates comparable to those for nonbridged heart transplant recipients.

Left ventricular diastolic filling with an implantable ventricular assist device: beat to beat variability with overall improvement

OBJECTIVES

We studied the effects of left ventricular (LV) unloading by an implantable ventricular assist device on LV diastolic filling.

BACKGROUND

Although many investigators have reported reliable systemic and peripheral circulatory support with implantable LV assist devices, little is known about their effect on cardiac performance.

METHODS

Peak velocities of early diastolic filling, late diastolic filling, late to early filling ratio, deceleration time of early filling, diastolic filling period and atrial filling fraction were measured by intraoperative transesophageal Doppler echocardiography before and after insertion of an LV assist device in eight patients. A numerical model was developed to simulate this situation.

RESULTS

Before device insertion, all patients showed either a restrictive or a monophasic transmitral flow pattern. After device insertion, transmitral flow showed rapid beat to beat variation in each patient, from abnormal relaxation to restrictive patterns. However, when the average values obtained from 10 consecutive beats were considered, overall filling was significantly normalized from baseline, with early filling velocity falling from 87 +/- 31 to 64 +/- 26 cm/s (p < 0.01) and late filling velocity rising from 8 +/- 11 to 32 +/- 23 cm/s (p < 0.05), resulting in an increase in the late to early filling ratio from 0.13 +/- 0.18 to 0.59 +/- 0.38 (p < 0.01) and a rise in the atrial filling fraction from 8 +/- 10% to 26 +/- 17% (p < 0.01). The deceleration time (from 112 +/- 40 to 160 +/- 44 ms, p < 0.05) and the filling period corrected by the RR interval (from 39 +/- 8% to 54 +/- 10%, p < 0.005) were also significantly prolonged. In the computer model, asynchronous LV assistance produced significant beat to beat variation in filling indexes, but overall a normalization of deceleration time as well as other variables.

CONCLUSIONS

With LV assistance, transmitral flow showed rapidly varying patterns beat by beat in each patient, but overall diastolic filling tended to normalize with an increase of atrial contribution to the filling. Because of the variable nature of the transmitral flow pattern with the assist device, the timing of the device cycle must be considered when inferring diastolic function from transmitral flow pattern.

Management of left ventricular assist device infection with heart transplantation

BACKGROUND

Left ventricular assist devices (LVADs) are being used as bridges to heart transplantation (HT). Infection of the LVAD in this patient population represents a serious complication, as simple LVAD removal or delaying HT may result in death. To improve outcomes in this group of patients, we performed HT in the presence of LVAD infection.

METHODS

Eighteen patients underwent LVAD implantation followed by HT. Ten underwent HT in the absence of LVAD infection (group 1); and 8, in the presence of LVAD infection (group 2). All patients were treated similarly except for modification of immunosuppression in group 2 patients.

RESULTS

Infectious and noninfectious complications were equivalent between the two groups. There was no difference between groups in regard to intraoperative deaths (one versus none), long-term survival (8/10 versus 7/8), wound complications (three versus none), and mean length of hospital stay after HT (21 versus 26 days).

CONCLUSIONS

Patients with LVAD infection are too seriously ill to allow LVAD removal or delay of HT. Transplantation in the face of infection is an effective treatment option.

Effects of exercise during long-term support with a left ventricular assist device. Results of the experience with left ventricular assist device with exercise (EVADE) pilot trial

BACKGROUND

Long-term implantation of a left ventricular assist device (LVAD) may be a future alternative treatment for end-stage heart failure. The objective of the present study was to determine the hemodynamic effects of supine bicycle exercise and functional capacity during upright treadmill exercise in 10 patients after LVAD implantation placed for refractory heart failure as a bridge to cardiac transplantation.

METHODS AND RESULTS

With supine bicycle exercise, 46 +/- 25 days after device placement, heart and LVAD rates increased in parallel from 87 +/- 12 to 117 +/- 14 bpm and 82 +/- 18 to 107 +/- 21 bpm, respectively. Peak O2 consumption was 8.2 +/- 1.7 mL O2.kg-1.min-1. Fick Systemic blood flow rose from 5.0 +/- 1.2 to 7.8 +/- 2.5 L/min. Right atrial and pulmonary capillary wedge pressures increased from 6 +/- 4 and 5 +/- 3 mm Hg to 12 +/- 5 and 13 +/- 8 mm Hg, respectively. End-diastolic left ventricular dimension increased from 3.9 +/- 1.3 to 4.8 +/- 1.6 cm; however, right ventricular dimension decreased from 3.2 +/- 1.0 to 2.3 +/- 0.9 cm. With upright treadmill exercise, peak O2 consumption was 14.1 +/- 2.9 mL O2.kg-1.min-1.

CONCLUSIONS

This study indicates that exercise during long-term LVAD support is safe and is not limited by right heart decompensation. It also justifies a larger study to examine how exercise after LVAD implantation compares with that after cardiac transplantation.

The continuing evolution of mechanical ventricular assistance

A great number of patients suffer and die of the sequelae of acute and chronic heart failure each year. Although advances in medical and surgical therapy have benefited many of these patients, most have disease that is refractory to any definitive therapy. For these patients cardiac transplantation is the only remaining hope. Unfortunately, because of the increasing demand for donor organs in the face of a fixed and limited supply, this option is available to only a small percentage of these patients. Even in patients accepted for transplantation, a significant waiting list mortality has been observed. A variety of VADs have been developed since the first successful case of mechanical cardiac assistance more than 30 years ago. These devices differ in basic mechanical function, method of insertion, and degree of implantability and thus have different indications and potential applications. Whereas the intraaortic balloon pump and centrifugal pumps are effective short-term support modalities, extracorporeal and implantable pulsatile devices have been used successfully for long-term support of patients with reversible and nonreversible cardiac failure. Although these pumps have most commonly been used as bridges to transplantation, increasing clinical experience has supported the notion of long-term mechanical assistance as a definitive therapy for patients with end-stage heart disease. Although complications, particularly infection and thromboembolism, pose significant challenges and long-term device reliability remains to be fully determined, available implantable devices appear to be capable of providing effective long-term support. As data are obtained from currently ongoing trials comparing VAD support with medical therapy for end-stage heart failure, ethical and economic issues will assume increasing importance.

Risk of left ventricular assist device as a bridge to heart transplant following postinfarction ventricular septal rupture

Heart transplantation is an effective treatment for end-stage heart failure. However, due to the persistent shortage of donor hearts, many patients die awaiting a transplant. Implantable left ventricular assist devices are now available as a reliable bridge to cardiac transplantation. This report presents a patient with terminal heart failure as a result of a post-myocardial infarction ventricular septal rupture (VSR), who underwent a successful placement of the HeartMate left ventricular assist device (LVAD) and velour patch closure of an apical VSR. Despite this therapy, the patient expired after developing a second VSR, which created a high-flow right-to-left shunt and caused hypoxic irreversible brain injury. We suggest that use of a left ventricular assist device as a bridge to transplantation be approached with extreme caution in a patient with a postinfarction ventricular septal rupture.

Low thromboembolic risk without anticoagulation using advanced-design left ventricular assist devices

BACKGROUND

A major limitation of cardiac assist devices has been the high incidence of thromboembolic events and their requirement for systemic anticoagulation. The Thermo Cardiosystems HeartMate 1000 IP left ventricular assist device (LVAD) employs a design that may reduce thromboembolic risk and obviate the need for systemic anticoagulation.

METHODS

Two hundred twenty-three patients with nonreversible heart failure were supported with the HeartMate LVAD as a bridge to heart transplantation. All patients were monitored prospectively for thromboembolic events. Anticoagulation regimens and occurrence of subclinical thromboembolic events, including those seen by transcranial Doppler examinations in selected patients, were also recorded.

RESULTS

Total time of LVAD support use was 531.2 patient-months. Twenty-three patients (10%) received warfarin postoperatively for 42.4 patient-months (8.2% of total support time). Six patients (2.7%) had thromboembolic events, representing 0.011 events per patient-month of device use.

CONCLUSIONS

The thromboembolic complication rate associated with this LVAD is acceptably low despite the minimal anticoagulation employed in this series, allowing consideration of long-term device use for the treatment of heart failure.

Left ventricular echocardiographic and histologic changes: impact of chronic unloading by an implantable ventricular assist device

OBJECTIVES

We studied the effects of chronic left ventricular unloading by a ventricular assist device and assessed left ventricular morphologic and histologic changes.

BACKGROUND

The implantable left ventricular assist device has been effective as a "bridge" to cardiac transplantation. Although there are reports documenting its circulatory support, little is known about the effects of chronic left ventricular unloading on the heart itself.

METHODS

We performed intraoperative transesophageal echocardiography at the insertion and explanation of a HeartMate left ventricular assist device in 19 patients with end-stage heart failure. They were supported by the assist device for 3 to 153 days (mean [+/-SD] 68 +/- 33). Measurements were taken retrospectively to obtain left atrial and ventricular diameters and interventricular septal and posterior wall thicknesses. Histologic examinations were made from the left ventricular myocardial specimens of 15 patients at the times of insertion and explanation for heart transplantation. Insertion and explanation specimens were compared qualitatively (0 to 3 scale) for wavy fibers, contraction band necrosis and fibrosis, with quantitative measurement of minimal myocyte diameter across the nucleus.

RESULTS

Left atrial and left ventricular diastolic and systolic diameters decreased immediately after insertion of the left ventricular assist device (from 46 to 35, 63 to 41 and 59 to 36 mm, respectively, all p < 0.001). Left ventricular wall thickness increased from 10 to 14 mm (p < 0.001) for the interventricular septum and from 10 to 13 mm for the posterior wall (p<0.001). No echocardiographic measurements showed significant subsequent changes at the chronic stage. Myocardial histologic findings demonstrated a reduction in myocyte damage (from 1.9 to 0.5, p<0.001, for wavy fiber and from 1.3 to 0.2, p<0.01, for contraction band necrosis) and an increase in fibrosis (from 1.3 to 1.9, p<0.05), but without significant change in myocyte diameter (from 15.6 to 16.8 micrometer, p=0.065).

CONCLUSIONS

Left ventricular unloading with the implantable assist device induces an immediate increase in wall thickness, consistent with the reduction in chamber size, thereby decreasing wall stress. Chronic unloading allows myocardial healing and fibrosis without evidence for ongoing myocyte damage or atrophy. Left ventricular assist device insertion may have a role in "resting" the ventricle for selected patients with heart failure.

Infections during extended circulatory support: University of Alabama at Birmingham experience 1989 to 1994

BACKGROUND

The University of Alabama at Birmingham experience with investigational ventricular assist devices (VADs) used as a bridge to transplantation has increased over the past several years; it now includes 27 VAD implantations with 13 VAD runs lasting for extended periods (ie, > 30 days). A review of complications experienced by patients during extended VAD runs is warranted before the further development and testing of chronically implanted mechanical circulatory support devices.

METHODS

This study focuses on the infectious complications of extended VAD support; it includes 13 patients who were supported by either a Thoratec or HeartMate VAD for longer than 30 days pending cardiac transplantation. Infection was defined as any positive culture. The infections were classed according to site and severity as follows: class I were patient-related non-blood-borne infections, class II were blood-borne infections, class III were VAD percutaneous site infections, and class IV were infections of the blood-contacting surfaces or intracorporeal components of the VAD.

RESULTS

The 8 Thoratec and 5 HeartMate patients were supported for a total of 1,648 days with a range of 33 to 279 days per patient. Every patient had at least one infection; however, there were 6 patients who had no class II or IV infections during the period of support. One of these 6 patients died of a stroke, whereas the other 5 patients survived VAD support. No trends were identified for a change in the incidence of bacterial compared with fungal infections during the course of VAD support. There was no trend for a greater number of infections in patients who died during VAD support compared with those who survived. Neither class II nor IV infections precluded transplantation. Three patients died during VAD support; 1 died as a direct consequence of fungal infection. Eight patients received transplants. One patient had an unanticipated recovery of cardiac function and the VAD was removed. Support in 1 patient is ongoing.

CONCLUSIONS

Infection during VAD support pending cardiac transplantation is an important cause of morbidity and mortality in patients maintained for longer than 30 days by circulatory assist. Infectious complications will probably be a prominent component of the risk associated with the use of chronically implanted mechanical circulatory assist devices and will likely have an important effect on the quality of life experienced by these patients.

HeartMate implantable left ventricular assist device: bridge to transplantation and future applications

The HeartMate implantable left ventricular assist device (LVAD) is approaching the time when it will be implanted permanently. Experience with the HeartMate 1000 IP LVAD at the Cleveland Clinic as a bridge to heart transplantation in 21 patients has shown (1) excellent hemodynamic function [improving cardiac index from a mean +/- standard deviation of 1.6 +/- 0.26 L.min-1.m-2 to 3.0 +/- 0.42 L.min-1.m-2]; (2) 81% survival before transplantation with a mean duration of 64 +/- 34 days of LVAD support; (3) 100% survival after transplantation; (4) New York Heart Association class IV and moribund patients were returned to class I or II status while on the LVAD; and (5) a remarkably low risk of thromboemboli during 1,583 patient-days of support. The multicenter experience (173 patients) confirms the low risk of embolic events (2%, including septic emboli). A "target population" for initial use of the permanent device was outlined from a retrospective review of 570 patients. A subgroup of 74 patients (13%) were between 18 and 75 years of age, had isolated cardiac failure (without multiple comorbidities), and required inotropic medications, intraaortic balloon pump support, or both. Survival for this patient group (mean age, 57 +/- 13 years; 68% male) was poor: median survival was 7 months, 21.6% died during the hospitalization, and 47.3% died after discharge. Of the survivors, only 4 patients (5% of the initial 74 patients) were in New York Heart Association class I. From the bridge-to-transplantation experience we extrapolate that survival and quality of life should improve for patients in the target population treated with the portable LVAD.(ABSTRACT TRUNCATED AT 250 WORDS)

The Linköping-Lund surgical experience with the HeartMate left ventricular assist system

Four transplant candidates fulfilling the Food and Drug Administration criteria for a permanent left ventricular assist device received a pneumatic HeartMate system as a bridge to heart transplantation. All patients survived and were fully rehabilitated at the time of transplantation, which was carried out 2 to 6 months after the initial operation. There were no major complications associated with the procedures. We are impressed by the effectiveness and safety of the device.