Bridge experience with long-term implantable left ventricular assist devices. Are they an alternative to transplantation?

Expanding the heart donor pool: Can left ventricular assist devices substitute for marginal donor heart allografts?

BACKGROUND

Generally, heart transplantation with marginal donor allografts is reserved for a subset of high-risk patients. However, given the improved survival rates for patients on left ventricular assist devices, it is worth analyzing if they could potentially substitute for marginal donor allografts. This study aimed to compare survival outcomes of waitlisted patients with left ventricular assist devices who did not undergo heart transplantation to those who underwent heart transplantation with marginal allografts.

METHODS

This was a retrospective cohort study of adults (≥18 years) listed for heart transplantation between 2010 and 2022 in the Organ Procurement and Transplantation Network database. A previously validated risk score was used to define marginal donor organs. The primary outcome was death after transplantation or on the waitlist, as appropriate.

RESULTS

Of 5,713 patients with left ventricular assist devices, 4,683 (82%) comprised the left ventricular assist devices group and 1,030 (18%) the marginal group. The marginal cohort was older (57 [49-64] vs 55 [45-62] years, P < .001), similarly female (26 vs 24%, P = .16), and less often White (51 vs 60%, P < .001). Relative to the left ventricular assist devices group, the marginal group demonstrated higher 5-year survival from 2010 to 2014 (81 vs 43%, P < .001) and from 2015 to 2019 (77 vs 66%, P < .001). After adjustment, marginal patients demonstrated a significantly reduced hazard of 5-year mortality for those listed from 2010 to 2014 (hazard ratio 0.25, confidence interval 0.20-0.31; P < .001) and from 2015 to 2019 (hazard ratio 0.46, confidence interval 0.37-0.57; P < .001).

CONCLUSION

Our study validates the superiority of transplantation relative to left ventricular assist devices but also underscores the survival benefit of heart transplantation with marginal donor allografts, even in high-risk patients.

Detecting Suspected Pump Thrombosis in Left Ventricular Assist Devices via Acoustic Analysis

OBJECTIVE

Left ventricular assist devices (LVADs) fail in up to 10% of patients due to the development of pump thrombosis. Remote monitoring of patients with LVADs can enable early detection and, subsequently, treatment and prevention of pump thrombosis. We assessed whether acoustical signals measured on the chest of patients with LVADs, combined with machine learning algorithms, can be used for detecting pump thrombosis.

METHODS

13 centrifugal pump (HVAD) recipients were enrolled in the study. When hospitalized for suspected pump thrombosis, clinical data and acoustical recordings were obtained at admission, prior to and after administration of thrombolytic therapy, and every 24 hours until laboratory and pump parameters normalized. First, we selected the most important features among our feature set using LDH-based correlation analysis. Then using these features, we trained a logistic regression model and determined our decision threshold to differentiate between thrombosis and non-thrombosis episodes.

RESULTS

Accuracy, sensitivity and precision were calculated to be 88.9%, 90.9% and 83.3%, respectively. When tested on the post-thrombolysis data, our algorithm suggested possible pump abnormalities that were not identified by the reference pump power or biomarker abnormalities.

SIGNIFICANCE

We showed that the acoustical signatures of LVADs can be an index of mechanical deterioration and, when combined with machine learning algorithms, provide clinical decision support regarding the presence of pump thrombosis.

Management and outcomes of left ventricular assist device-associated endocarditis: a systematic review

Background

Left ventricular assist device (LVAD)-associated endocarditis remains poorly studied, especially in newer continuous-flow LVADs (CF-LVADs). The aim of this review was to assess outcomes of patients with LVAD-associated endocarditis, as stratified by CF-LVAD and pulsatile LVAD (P-LVAD) use as well as by different interventions and pathogen types.

Methods

An electronic search was performed to identify studies in the English literature on LVAD-associated endocarditis.

Results

Overall, 16 articles with 26 patients were included; seven had CF-LVADs and 19 had P-LVADs; time to development of endocarditis was 91 days (152 vs. 65 days, respectively, P=0.05). Eleven of 25 patients were treated with antibiotics only. Remaining 14 patients received antibiotics, however, they also underwent additional surgical intervention. One patient was treated with embolization alone for mycotic aneurysm and was therefore excluded. At a median follow-up time of 344 days post implant, there was no difference in overall mortality between CF-LVAD and P-LVAD-associated endocarditis patients (57.9% vs. 42.9%, P=0.81). Patients who underwent additional surgical intervention had higher overall survival compared to those treated with antibiotics alone (71.4% vs. 27.3%, P=0.07); with no difference in outcomes amongst those who underwent surgical device exchange as compared to heart transplantation (80.0% vs. 66.7%; P=0.23).

Conclusions

Compared to patients with P-LVADs, CF-LVAD patients appeared to be resistant to early development of LVAD-associated endocarditis. There was a trend towards high survival observed amongst patients who underwent additional surgical intervention as compared to those treated with antibiotics alone, with no difference amongst surgical device exchange as compared to heart transplantation. Advantages of additional surgical intervention vs. medical therapy alone deserves further exploration to determine its applicability in CF-LVADs.

False positive hepatitis C antibody test results in left ventricular assist device recipients: increased risk with age and transfusions

Left ventricular assist devices (LVADs) have been successfully used in patients with heart failure. However, LVADs may trigger immune activation, leading to higher frequencies of autoantibodies. We describe the clinical, epidemiological, and laboratory characteristics of LVAD recipients with false positive hepatitis C (FPHC) serology among 39 consecutive adult LVAD recipients who bridged to heart transplantation from January 2007 to January 2013 at Montefiore Medical Center. FPHC patients were identified as those with post-LVAD positive hepatitis C ELISA antibody tests and negative confirmatory testing with hepatitis C RNA PCR and/or radioimmunoblot assay. Ten (26%) patients previously seronegative for hepatitis C were found to have FPHC after device placement. Of the 39 patients, 32 had HeartMate II devices. The mean age at LVAD placement was 55 years. FPHC correlated with older age at the time of LVAD implantation and with receipt of packed red blood cell transfusions, but not with gender, fresh frozen plasma transfusions, panel reactive antibodies, globulin fraction, rheumatoid factor, or anticardiolipin antibodies. Clinicians should be aware of this increased risk of FPHC in older LVAD patients and those more heavily transfused in order to avoid unnecessary apprehension and possible delay in transplantation. Further studies should be done to evaluate the possible relationship between transfused blood products and immunomodulation.

Endocarditis in left ventricular assist device

Heart failure is one of the leading causes of death in developed nations. End stage heart failure often requires cardiac transplantation for survival. The left ventricular assist device (LVAD) has been one of the biggest evolvements in heart failure management often serving as bridge to transplant or destination therapy in advanced heart failure. Like any other medical device, LVAD is associated with complications with infections being reported in many patients. Endocarditis developing secondary to the placement of LVAD is not a frequent, serious and difficult to treat condition with high morbidity and mortality. Currently, there are few retrospective studies and case reports reporting the same. In our review, we found the most common cause of endocarditis in LVAD was due to bacteria. Both bacterial and fungal endocarditis were associated with high morbidity and mortality. In this review we will be discussing the risk factors, organisms involved, diagnostic tests, management strategies, complications, and outcomes in patients who developed endocarditis secondary to LVAD placement.

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.

Management of patients with implanted ventricular assist devices for noncardiac surgery: a clinical review

While originally primarily used as bridge to cardiac transplantation and bridge to recovery, more commonly ventricular assist devices (VADs) are being inserted as destination therapy. These patients are being discharged from transplant and mechanical assist centers, living as outpatients, and thus the pool of community-dwelling patients with VADs continues to expand. Not infrequently they present for surgical procedures either directly related to the device itself or more often incidental to the fact that they have a VAD. This scenario may be more common in patients with VADs placed for destination therapy because these patients tend to be older and have more comorbidities and are living longer with their device. Thus, it is important for all anesthesiologists to be aware of the special anesthesia needs of patients with VADs requiring noncardiac surgery.

Left ventricular assist device to avoid heart-lung transplant in an adolescent with dilated cardiomyopathy and severely elevated pulmonary vascular resistance

Orthotopic heart transplantation remains the definitive treatment of choice for patients with end-stage heart failure; however, elevated PVRI is a reported risk factor for mortality after heart transplant and, when severely elevated, is considered an absolute contraindication. Use of a ventricular assist device has been proposed as one treatment for reducing pulmonary vascular resistance index in potential heart transplant candidates refractory to medical vasodilator therapies. We report on a teenage patient with dilated cardiomyopathy and severely elevated PVRI, unresponsive to pulmonary vasodilator therapy, who underwent left ventricular assist device implantation to safely allow for aggressive pulmonary vasodilator therapy and to decrease PVRI. The resulting dramatic improvement in PVRI in a relatively short period of time allowed for successful heart transplantation, avoiding the need for heart-lung transplant.

Advances and future directions for mechanical circulatory support

Although cardiac transplant remains the gold standard for the treatment of end-stage heart failure, limited donor organ availability and growing numbers of eligible recipients have increased the demand for alternative therapies. Limitations of first-generation left ventricular assist devices for long-term support of patients with end-stage disease have led to the development of newer second-generation and third-generation pumps, which are smaller, have fewer moving parts, and have shown improved durability, allowing for extended support. The HeartMate II (second generation) and HeartWare (third generation) are 2 devices that have shown great promise as potential alternatives to transplantation in select patients.

Right side of heart failure

The function of the right ventricle (RV) in heart failure (HF) has been mostly ignored until recently. A 2006 report of the National Heart, Lung, and Blood Institute identified a gap between RV research efforts and its clinical importance compared with that of the left ventricle. This recent shift in paradigm is fueled by the prognostic value ascribed to RV failure in HF and morbidity/mortality after myocardial infarction and surgery. In this review, we examine the significance of RV failure in the HF setting, its clinical presentation and pathophysiology, and ways to evaluate RV function using echocardiographic measurements. Furthermore, we discuss the medical management of RV failure including traditional therapies like beta-blockers and newer options like nitric oxide, phosphodiesterase inhibitors, and calcium sensitizers. Mechanical support is also examined. Finally, this review places an emphasis on RV failure in the setting of left ventricular assist devices and heart transplantation.

Cavoaortic shunt improves hemodynamics with preserved oxygen delivery in experimental right ventricular failure during left ventricular assist device therapy

OBJECTIVE

Right heart failure is a major cause of morbidity and mortality after left ventricular assist device (LVAD) implantation. This study evaluated the approach of a cavoaortic shunt included in the LVAD circuit, which would aim to relieve venous congestion and improve hemodynamics with preserved oxygen delivery during induced right ventricular failure.

METHODS

Right ventricular failure was induced by coronary ligation in 10 pigs. An LVAD was implanted and a cavoaortic shunt was created from the right atrium and included in the assist circuit. Hemodynamic measures and blood gas analyses were analyzed. Oxygen delivery and oxygen consumption were estimated.

RESULTS

Right atrial pressure decreased from more than 20 mm Hg to 17.2 mm Hg (14.8-18.4) with the LVAD and to 14.1 mm Hg (11.2-15.5) (P < .01) with the LVAD and cavoaortic shunt. Mean arterial pressure increased from 70.9 mm Hg (67.6-79.8) to 81.5 mm Hg (70.8-92.6) (P = .02) with addition of the shunt into the assist circuit. Cardiac output increased from 3.5 L/min (2.6-4.2) to 4.9 L/min (3.5-5.6) (P < .01) with cavoaortic shunting. Oxygen delivery with the cavoaortic shunt was 337 mL/min (± 70) as compared with left ventricular assist alone at 258 mL/min (± 52) (P < .01). Oxygen consumption was restored during use of the cavoaortic shunt.

CONCLUSIONS

A cavoaortic shunt combined with an LVAD during right ventricular failure reduces central venous pressures, increases systemic arterial pressure, and enables increased cardiac output compared with device therapy alone. This was feasible with preserved oxygen delivery.

The spectrum of complications following left ventricular assist device placement

INTRODUCTION

Left ventricular assist device (LVAD) support is associated with many complications, but relatively few studies have examined the full spectrum of complications beyond infectious and bleeding events.

METHODS

We conducted a retrospective review of patients receiving either a pulsatile-flow Heartmate XVE (HM1; Thoratec Corp., Pleasanton, CA, USA) or continuous-flow Heartmate II (HM2; Thoratec Corp.) LVAD at our institution (June 2000 to March 2012). Frequency and date of onset of nonbleeding, noninfectious complications were examined.

RESULTS

One hundred eighty-two LVADs were implanted, 49 HM1, and 133 HM2. Support duration was longer for HM2s (median 358 vs. 112 days; p = 0.0003). Overall, the most frequent complications were respiratory failure, ventricular arrhythmia, atrial arrhythmia, right heart failure, and renal failure. Respiratory failure, arrhythmias, severe psychiatric events, and renal failure all occurred with median date of onset ≤ seven days postprocedure. Right heart failure, hepatic failure, thromboembolism, and transient ischemic attacks had a median date of onset 8 to 30 days postprocedure. Stroke, hemolysis, and device failure occurred mostly more than a month postoperatively. Right heart failure, hepatic failure, and device failure were more frequent in HM1 patients than in HM2 patients. Several events, including stroke, had much later onset in HM2 patients.

CONCLUSION

In this 10-year review of complications following LVAD implantation, the most common adverse events tended to occur early after implantation. As pulsatile-flow HM1s showed greater frequency and earlier onset of some adverse events, our data suggest better overall outcomes with the continuous-flow HM2s.

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.

Pulsatile left ventricular assist device support as a bridge to decision in patients with end-stage heart failure complicated by pulmonary hypertension

BACKGROUND

Severe pulmonary hypertension (PH) in heart failure (HF) is a risk factor for adverse outcomes after heart transplantation (HTx). Left ventricular assist devices (LVADs) improve pulmonary hemodynamics, but our understanding of the degree of improvement and the effect on outcomes is still evolving.

METHODS

We reviewed invasive pulmonary hemodynamics from 58 consecutive patients receiving LVAD support as a bridge to HTx from 1996 to 2003. The primary outcome was change in baseline transpulmonary gradient (TPG) during LVAD support and after HTx/recovery. The secondary outcome was post-HTx survival.

RESULTS

All patients (age, 49 +/- 14 years, 79% male, 40% ischemic) received a pulsatile LVAD (median support, 97 days; interquartile range [IQR], 31-222). Hemodynamic measurements were obtained at baseline (median, 1 day; IQR, 1-3), during early (median, 1 day; IQR, 0-4) and late (median, 75 days; IQR, 24-186) LVAD support, and after HTx/recovery (median, 28 days; IQR, 17-40). Improvement in TPG occurred throughout LVAD support and was sustained after HTx/recovery. Levels of TPG reductions in patients with a baseline TPG in the highest quartile (14.1-26.0 mm Hg) were 8.6 +/- 3.5 vs 6.5 +/- 3.1 mm Hg in the lowest quartile (2.0-7.7 mm Hg) during LVAD support (p = 0.102), with 90% vs 100% 30-day post-HTx survival (P = 0.113).

CONCLUSION

Pulmonary hemodynamics and post-HTx survival were similar after pulsatile LVAD support in patients with and without pre-implant PH. LVAD support may be a useful strategy to reverse PH in carefully selected patients, thus improving candidacy for HTx.

Ventricular assist device therapy

Ventricular assist devices are an important therapeutic option for advanced congestive heart failure. A left ventricular assist device (LVAD) can be implanted as a bridge to transplantation or for the purpose of destination therapy. LVADs improve end-organ function and reduce morbidity and mortality in appropriately selected patients. The development of axial flow pumps has overcome many of the limitations of the first-generation pulsatile flow LVADs. However, many complications of LVAD therapy remain. Treating these complications requires an understanding of LVAD physiology. Ongoing research is directed at reducing the incidence of many of these complications and may allow for wider use of LVADs.

Renal function and outcome after continuous flow left ventricular assist device implantation

BACKGROUND

Renal dysfunction as a risk factor with the use of left ventricular assist devices (LVAD) is controversial. We determined the effect of renal function on outcomes after continuous flow LVAD implantation.

METHODS

Eighty-six patients with advanced heart failure undergoing continuous flow LVAD implantation as bridge to transplantation from November 1998 to July 2007 were retrospectively analyzed. Renal function was assessed using the Modification of Diet in Renal Disease study-derived glomerular filtration rates (GFR [mL x min(-1) x 1.73 m(-2)]). Patients were categorized into two groups based on pre-LVAD GFR: those with normal renal function (GFR > 60, n = 46), and those with renal dysfunction (GFR < 60, n = 40).

RESULTS

Post-LVAD survival at 1, 3, and 6 months for GFR greater than 60 was 91.3%, 79.9%, 72.6%, respectively, and for GFR less than 60, it was 92.5%, 66.5%, 47.9%, respectively (p = 0.038). Bridge-to-transplant rate was lower for GFR less than 60 than for GFR greater than 60 (40.0% versus 63.0%, p = 0.033). For GFR less than 60, GFR improved on LVAD support: implant to month 6, 41.7 +/- 11.5 to 62.7 +/- 25.0 (p = 0.021). Post-LVAD survival was improved in GFR less than 60 patients who after LVAD implantation recovered renal function to GFR greater than 60 (p < 0.001). Patients with post-LVAD renal failure had significantly lower post-LVAD survival regardless of pre-LVAD renal function (p < 0.001).

CONCLUSIONS

Patients with renal dysfunction have poorer outcomes after continuous flow LVAD implantation. However, renal function improves after LVAD implantation and is associated with improved survival. Our data underscore the importance of end-organ function in patient selection for LVAD therapy.

Outcome of noncardiac surgery in patients with ventricular assist devices

An increasing number of patients are living with ventricular assist devices (VADs). Many of these patients will require noncardiac surgery for conditions not directly related to their VADs. The aim of this study was to assess the risks and outcomes of noncardiac surgery in these patients. Perioperative and follow-up data from patients with VADs who underwent noncardiac surgery from 1993 to 2006 were analyzed. In that period, 184 VADs were implanted in 155 patients. Thirty-seven patients (24%) subsequently underwent 59 noncardiac surgeries. The mean duration of VAD support before surgery was 229 days. Bleeding was the most common postsurgical complication (10%), necessitating reexploration in 20% of abdominal surgeries. Thirty-day mortality was 12%. No deaths were caused by direct complications of surgery. Successful transplantation occurred in 72% of bridge to transplantation patients who required noncardiac surgery, compared with 71% of these patients who did not require noncardiac surgery (relative risk 1.0, p = 0.9). The average duration of VAD support after noncardiac surgery for destination therapy patients was 324 days, most of which time was spent at home. In conclusion, outcomes after noncardiac surgery in patients with VADs are favorable, and most patients continue to benefit from the intended purpose of mechanical circulatory support after recovering from noncardiac surgery.

Tricuspid annular motion as a predictor of severe right ventricular failure after left ventricular assist device implantation

BACKGROUND

Right ventricular (RV) failure after left ventricular assist device (LVAD) implantation is associated with a high rate of morbidity and mortality. We sought to determine pre-operative right heart echocardiographic predictors of post-LVAD severe RV failure.

METHODS

RV failure, defined as the need for inotropic support or pulmonary vasodilators for >or=14 days post-operatively, was evaluated in 33 patients (age 54 +/- 13 years) with LVADs. Preoperative RV systolic and diastolic echocardiographic parameters, including RV fractional area change, tricuspid annular motion, right atrial volume index, RV index of myocardial performance, hepatic vein Doppler velocities, tricuspid regurgitation severity, and RV systolic pressures (RVSPs) in patients with and without RV failure were compared.

RESULTS

Of the 33 patients evaluated, 11 (33%) had post-LVAD RV failure (2 needed RVAD support). Patients with post-LVAD RV failure had significantly lower pre-operative tricuspid annular motion (8 +/- 4 vs 15 +/- 6 mm, p < 0.01) and higher RVSPs (60 +/- 14 vs 46 +/- 11 mm Hg, p = 0.02). In 13 patients (39%) with moderate tricuspid regurgitation, pre-operative tricuspid annular motion remained significantly reduced (6.0 +/- 0.5 vs 13.5 +/- 5.0 mm, p = 0.045). Other echocardiographic parameters were not significantly different between patients. Tricuspid annular motion of <7.5 mm provides 91% specificity and 46% sensitivity in predicting post-LVAD RV failure.

CONCLUSION

Tricuspid annular motion is a predictor of post-LVAD RV failure. Using tricuspid annular motion in addition to conventional criteria may aid in early identification of patients with prolonged inotropic support or severe RV failure and allow for better pre-operative planning.

Mechanical circulatory support: a clinical reality

Mechanical circulatory support is becoming an alternative therapeutic option for patients in cardiogenic shock or advanced cardiac failure who cannot be improved by maximal medical therapy. More than 30 years of engineering development and clinical research have led to a level of efficacy and reliability of ventricular assist devices, which allows promotion of this approach for the most difficult patients. Uses include a gaining-time strategy as a bridge to cardiac transplantation or recovery of native cardiac function, as well as permanent support with the device. The large variety of devices permits every cardiac surgical unit, even those not used to cardiac transplantation, to propose this option to the patient. Recent experience with small silent implantable pumps suggests that the pioneering period of mechanical circulatory support is probably over, and the time has come for precise prospective trials to optimize both patient selection and the timing for utilization. In countries where cardiac transplantation has not developed, there is now an easily accessible technique for management of patients with cardiac failure.

Reverse cardiac remodeling enabled by mechanical unloading of the left ventricle

Cardiac remodeling is a characteristic and basic component of heart failure progression and is associated with a poor prognosis. Attenuating or reversing remodeling is an accepted goal of heart failure therapy. Cardiac mechanical support with left ventricular assist devices, in addition to its established role as "bridge to transplantation" or "destination therapy" in patients not eligible for cardiac transplantation, offers the potential for significant and sustained myocardial recovery through reverse remodeling. This review discusses the emerging role of left ventricular assist devices as a "bridge to recovery". Clinical and basic aspects of cardiac remodeling and cardiac reverse remodeling enabled by mechanical unloading, potential candidates for this modality of treatment as well as unresolved issues regarding the use of mechanical circulatory support as a bridge to recovery are discussed.

The right ventricular failure risk score a pre-operative tool for assessing the risk of right ventricular failure in left ventricular assist device candidates

OBJECTIVES

This study sought to develop a model that estimates the post-operative risk of right ventricular (RV) failure in left ventricular assist device (LVAD) candidates.

BACKGROUND

Right ventricular failure after LVAD surgery is associated with increased morbidity and mortality, but identifying LVAD candidates at risk for RV failure remains difficult.

METHODS

A prospectively collected LVAD database was evaluated for pre-operative clinical, laboratory, echocardiographic, and hemodynamic predictors of RV failure. Right ventricular failure was defined as the need for post-operative intravenous inotrope support for >14 days, inhaled nitric oxide for > or =48 h, right-sided circulatory support, or hospital discharge on an inotrope. An RV failure risk score (RVFRS) was created from multivariable logistic regression model coefficients, and a receiver-operating characteristic curve of the score was generated.

RESULTS

Of 197 LVADs implanted, 68 (35%) were complicated by post-operative RV failure. A vasopressor requirement (4 points), aspartate aminotransferase > or =80 IU/l (2 points), bilirubin > or =2.0 mg/dl (2.5 points), and creatinine > or =2.3 mg/dl (3 points) were independent predictors of RV failure. The odds ratio for RV failure for patients with an RVFRS < or =3.0, 4.0 to 5.0, and > or =5.5 were 0.49 (95% confidence interval [CI] 0.37 to 0.64), 2.8 (95% CI 1.4 to 5.9), and 7.6 (95% CI 3.4 to 17.1), respectively, and 180-day survivals were 90 +/- 3%, 80 +/- 8%, and 66 +/- 9%, respectively (log rank for linear trend p = 0.0045). The area under the receiver-operating characteristic curve for the RVFRS (0.73 +/- 0.04) was superior to that of other commonly used predictors of RV failure (all p < 0.05).

CONCLUSIONS

The RVFRS, composed of routinely collected, noninvasive pre-operative clinical data, effectively stratifies the risk of RV failure and death after LVAD implantation.

Perioperative echocardiographic examination for ventricular assist device implantation

Ventricular assist devices (VADs) are systems for mechanical circulatory support of the patient with severe heart failure. Perioperative transesophageal echocardiography is a major component of patient management, and important for surgical and anesthetic decision making. In this review we present the rationale and available data for a comprehensive echocardiographic assessment of patients receiving a VAD. In addition to the standard examination, device-specific pre-, intra-, and postoperative considerations are essential to the echocardiographic evaluation. These include: (a) the pre-VAD insertion examination of the heart and large vessels to exclude significant aortic regurgitation, tricuspid regurgitation, mitral stenosis, patent foramen ovale, or other cardiac abnormality that could lead to right-to-left shunt after left VAD placement, intracardiac thrombi, ventricular scars, pulmonic regurgitation, pulmonary hypertension, pulmonary embolism, and atherosclerotic disease in the ascending aorta; and to assess right ventricular function; and (b) the post-VAD insertion examination of the device and reassessment of the heart and large vessels. The examination of the device aims to confirm completeness of device and heart deairing, cannulas alignment and patency, and competency of device valves using two-dimensional, and color, continuous and pulsed wave Doppler modalities. The goal for the heart examination after implantation should be to exclude aortic regurgitation, or an uncovered right-to-left shunt; and to assess right ventricular function, left ventricular unloading, and the effect of device settings on global heart function. The variety of VAD models with different basic and operation principles requires specific echocardiographic assessment targeted to the characteristics of the implanted device.

Reverse remodeling during long-term mechanical unloading of the left ventricle

A significant proportion of patients placed on long-term mechanical circulatory support for end-stage heart failure can be weaned from mechanical assistance after functional recovery of their native heart ("bridge to recovery"). The pathophysiological mechanisms implicated in reverse remodeling that cause a sustained functional myocardial recovery have recently become the subject of intensive research, expected to provide information with a view to accurately identify reliable prognostic indicators of recovery. In addition, this kind of information will enable changes in the strategy of myocardial recovery by modifying the duration and scale of the unloading regimen or by combining it with other treatments that promote reverse remodeling.

Does total implantability reduce infection with the use of a left ventricular assist device? The LionHeart experience in Europe

BACKGROUND

Infection is the leading cause of death for left ventricular assist device (LVAD) patients with end-stage heart failure. Decreased infection may be possible with fully implantable LVADs such as the LionHeart, which lacks percutaneous conduits (PCs), a common source of device-related infection (DRI). This sub-study reports infections with the LionHeart and compares these results with historic data from the REMATCH trial, bridge to recovery (BTR) and bridge-to-transplantation (BTT) studies.

METHODS

Twenty-three patients were implanted with the LionHeart LVAD and followed until death or heart transplant during a non-randomized, multicenter, European trial from October 1999 to April 2004. The nature and incidence of infection were analyzed and adjudicated to definitions similar to, or the same as, the REMATCH definitions.

RESULTS

The combined number of implant days was 7,980, with a mean of 347 days (median 112, range 17 to 1,259 days). Survival at 1 year was 39%, with 2-year survival at 22%. Seventy-four percent of patients developed one or more infections, with 30% developing sepsis, and 35% developing pump-pocket infections (PSIs). No patients developed pump-housing or inflow- or outflow-tract infections (PI). For comparison, the prevalence rates of sepsis, PSI and PI in REMATCH were 51%, 35% and 19%, respectively.

CONCLUSIONS

The patients in the European LionHeart Clinical Utility Baseline Study (CUBS) trial had less sepsis and less overall DRI compared with the REMATCH LVAD group. Therefore, the fully implanted device may cause less infection than PC devices during destination therapy (DT). Although lower for DT, these rates are still higher than for some BTT experiences. Areas for future improvement include miniaturization of controller/battery components to reduce wound complications related to pocket size, and installation of more modern lithium-ion batteries to decrease the need for re-operations due to battery end-of-life.

Improved durability of the HeartMate XVE left ventricular assist device provides safe mechanical support up to 1 year but is associated with high risk of device failure in the second year

BACKGROUND

Life-threatening device failure of the HeartMate VE due to biologic inflow valve incompetence or motor failure is a major drawback of long-term mechanical support when using this left ventricular assist device (LVAD). The new XVE model is the result of recent technical improvements. The aim of this study was to compare the clinical performance and durability of the new and earlier HeartMate versions.

METHODS

We analyzed the incidence of device failure and of other device-specific complications (infections, bleeding) in 9 VE and 17 XVE patients. Explanted pumps were examined and biologic valve damage classified according to a score ranging from 0 (no visible damage) to 3 (severe destruction).

RESULTS

Mean support time was 145 +/- 92 and 267 +/- 195 days in the VE and XVE groups, respectively (difference not significant [NS]). Survival was 89% (VE) vs 75% (XVE). The incidence of device failure requiring urgent heart transplantation or device replacement was 44% (VE) vs 31% (XVE) (NS). Device failure occurred significantly later in the XVE group (200 +/- 34 vs 487 +/- 53 days, p < 0.01). Causes of device failure were inflow valve incompetence (n = 6) and motor failure (n = 3). Acute device failure caused 1 death in the XVE group. One XVE patient has been on mechanical support for > 483 days. Macroscopic inflow valve damage score after explantation of the devices was 2.2 +/- 1.1 in the VE group and 2.0 +/- 0.8 in the XVE group (NS).

CONCLUSIONS

The novel HeartMate XVE offers greater durability and provides reliable mechanical support in the first year. However, there is a high risk of life-threatening device failure in the second year. Further technical refinements are necessary to meet the challenges of safe long-term circulatory assistance.

Ventricular assist device-related infections

Heart failure is a leading cause of death in developed nations despite medical management. Cardiac transplantation is a potentially lifesaving intervention for approximately 4000 advanced heart failure patients per year; however, the demand for donor hearts far exceeds the supply. Ventricular assist devices provide temporary support for patients with severe heart failure until myocardial recovery occurs or a donor heart becomes available. For those ineligible for transplantation, ventricular assist devices may be used permanently and have demonstrated reduced mortality and an improved quality of life compared with continued medical therapy. Nonetheless, these devices are under-used, in part due to the frequency of complications. Device-related infections are one of the most frequent sequelae of ventricular assist device placement and occur in 18-59% of cases. Infections can involve any part of the device and confer substantial morbidity and mortality. Here, we provide an introduction to ventricular assist devices, explore the nature and pathogenesis of ventricular assist device-related infections, discuss problems with diagnosis, and present treatment and prevention strategies.

Cognitive Dysfunction in Advanced Heart Failure and Prospective Cardiac Assist Device Patients

BACKGROUND

Extended periods of hypoperfusion in an advanced heart failure (HF) places patients at high risk for neurobehavioral compromise, which has not been studied systematically. It is also not clear how intravenous inotropic therapy and mechanical cardiac assist devices (MCAD) affect cognitive function.

METHODS

This prospective cross-sectional cognitive preliminary study evaluated 252 potential heart transplant candidates assessing functions in memory, motor, and processing speed. Patients were divided into three HF groups based on severity of disease: group 1 outpatients (n = 113), group 2 in-patients requiring inotropic infusion (n = 83), and group 3 inpatients likely requiring MCAD support (n = 56). Aggregate z-scores for memory, motor, and processing speed and independent samples t tests assessed intergroup differences on 13 cognitive measures.

RESULTS

A broad pattern of cognitive impairment was observed within the advanced HF group; fewer deficits were found in group 1 outpatients and more severe deficits in group 3 MCAD subjects. A difference in motor functions was observed as the earliest abnormality, with group 3 showing significant changes compared with group 1. The most dramatic changes were seen in domain mental processing speed along with specific verbal and visual memory functions, which were slower in group 3 compared with groups 1 and 2.

CONCLUSIONS

Cognitive deficits are common in advanced HF and worsen with increasing severity of HF. Appropriately designed and randomized studies will be needed to demonstrate if earlier MCAD implantation is warranted to arrest cognitive dysfunction and better postimplantation adaptation.

Duration of inotropic support after left ventricular assist device implantation: Risk factors and impact on outcome

OBJECTIVES

Because duration of inotropic support after left ventricular assist device implantation has been recognized as a surrogate for right ventricular dysfunction, we sought to (1) identify its preimplantation risk factors, particularly its association with preimplantation right ventricular dysfunction, and (2) assess its impact on clinical outcomes.

METHODS

Between 1991 and 2002, left ventricular assist devices were implanted in 207 patients, exclusive of those receiving preoperative mechanical circulatory support, which precluded measuring right ventricular stroke work. Duration of inotropic support was analyzed as a continuous variable, truncated by death or transplantation, and in turn as a risk factor for these 2 events.

RESULTS

Inotropic support decreased from 100% on the day of implantation to 57%, 33%, and 22% by days 7, 14, and 21. Its duration was strongly associated with lower preimplantation right ventricular stroke work index, older age, and nonischemic cardiomyopathy and was associated (P < .04) with higher mortality before transplantation but not with transition to transplantation. We identified no preimplantation risk factors for right ventricular assist device use because of its relatively infrequent use in this population (18 patients, only 4 of whom survived to transplantation).

CONCLUSION

Duration of inotropic support after left ventricular assist device insertion is strongly correlated with low preimplantation right ventricular stroke work index. In turn, it was associated with reduced survival to transplantation. Thus, right ventricular stroke work measured before implantation might be useful in decision making for biventricular support, destination therapy, or total artificial heart.

Right ventricular failure after left ventricular assist device implantation: the need for an implantable right ventricular assist device

Right ventricular failure after implantation of a left ventricular assist device is an unremitting problem. Consideration of portal circulation is important for reversing liver dysfunction and preventing multiple organ failure after left ventricular assist device implantation. To achieve these objectives, it is imperative to maintain the central venous pressure as low as possible. A more positive application of right ventricular assistance is recommended. Implantable pulsatile left ventricular assist devices cannot be used as a right ventricular assist device because of their structure and device size. To improve future prospects, it is necessary to develop an implantable right ventricular assist device based on a rotary blood pump.

Comparison of Novacor and HeartMate Vented Electric Left Ventricular Assist Devices in a Single Institution

We compared the survival outcomes, left ventricular assist device (LVAD)-related hospitalization, stroke, infection, panel reactive antibody, and blood product use data among 13 Novacor and 51 HeartMate system recipients. Stroke was significantly higher in Novacor patients, as was blood product use at the time of heart transplantation, likely due to long-term anti-coagulation, while the LVAD-related hospitalization and infections did not differ between the 2 groups. A positive panel reactive antibody was seen more among the HeartMate patients, but did not have a significant clinical impact and may not represent a true allosensitization.

Left Ventricular Assist Devices as Bridge to Heart Transplantation in Congestive Heart Failure with Pulmonary Hypertension

Severe pulmonary hypertension (PH) has been considered a significant contraindication to cardiac transplantation. Ongoing clinical experience, however, has shown that temporary support using left ventricular assist devices (LVADs) in these patients can result in significant reductions in PH. A comprehensive review of the available literature regarding the use of LVADs in heart failure patients with PH was conducted. The existing literature to date supports the use of LVADs in heart failure patients with PH and demonstrates that significant reductions in PH in these patients can be achieved. This subsequently allows for safe and effective cardiac transplantation in patients who were previously excluded from this modality. For heart failure patients with severe PH, the use of LVADs can provide significant benefits by significantly reducing PH and allowing subsequent staged transplantation.

Blood Transfusions Decrease the Incidence of Acute Rejection in Cardiac Allograft Recipients

BACKGROUND

Cardiac transplant recipients frequently receive a large number of transfusions. The objective of this study was to determine whether there is an association between total number of blood transfusions and cardiac allograft rejection.

METHODS

A retrospective analysis of all cardiac transplants between October 1, 1997, and December 31, 2001, was performed. Total number of transfusions, total number of rejection episodes Grade 3A or more, rejection-free survival, and overall survival were analyzed. Comparisons between patients bridged to transplantation with a Novacor left ventricular assist device (LVAD) and the primary transplant group were also made.

RESULTS

Eighty-two patients were transplanted. Fifteen were bridged to transplantation, and 67 underwent primary heart transplantation. Age and sex were similar for the LVAD group and the primary transplant group (45 +/- 11 vs 47 +/- 15 years and 67% vs 58% male sex, respectively). Mean follow-up was 658 +/- 486 days for the LVAD group and 708 +/- 548 days for the primary transplant group. Transfusions received were 50 +/- 34 U of packed red blood cells for the LVAD group and 7 +/- 12 for the primary transplant group (p < 0.001). There were no differences in donor characteristics between the 2 groups. The incidence of acute rejection within 1 year was 27% for the LVAD group and 39% for the primary transplant group (p = .28). Freedom from rejection was 71% at 1 year in the LVAD group compared with 59% for the primary transplant group (p = 0.39). In all 82 patients, the total number of transfusions was inversely correlated with the development of acute rejection (p = 0.011). Survival was 80% and 62% for the LVAD group at 1 and 3 years after transplantation and 88% and 85%, respectively, for the primary transplant group (p = 0.045).

CONCLUSIONS

The number of blood transfusions received by heart transplant recipients is inversely related with the number of acute rejection episodes.