Effect of obesity on outcomes in patients who undergo implantation of a continuous-flow left ventricular assist device

Journal of Artificial Organs -     

Noninvasive blood pressure measurement in patients with continuous-flow left ventricular assist devices

Journal of Artificial Organs - Oscillatory blood pressure (OBP) with a slow cuff-deflation system has been proposed as noninvasive measurement of mean arterial pressure (MAP) in patients with...     

Effect of obesity on postoperative outcomes in patients with left ventricular assist device

Journal of Artificial Organs -     

Outcomes in patients with advanced heart failure and small body size undergoing continuous-flow left ventricular assist device implantation

Left ventricular assist devices (LVADs) have become a preferred treatment option for patients with end-stage heart failure when used as a bridge to transplant or as a destination therapy. However, the association between small body size and postoperative outcomes for continuous-flow (CF) LVAD recipients is still being studied. We sought to determine whether body surface area (BSA) is associated with patient outcomes after CF-LVAD implantation. The study cohort of our single-center, retrospective review consisted of all patients (n?=?526) who underwent CF-LVAD implantation (n?=?403 HeartMate II, n?=?123 HeartWare) between November 2003 and March 2016 regardless of indication. Patients were stratified into 2 cohorts according to their BSA measurements: small BSA (<1.5 m², n?=?13) and non-small BSA (≥1.5 m², n?=?513). We compared the survival of the small-BSA cohort with that of the non-small-BSA cohort. Patients with a small BSA had lower survival rates at 1, 6, 12, and 24 months (76.9, 61.5, 53.8, and 38.5%, respectively) than did patients with a non-small BSA (90.4, 80.9, 74.7, and 67.6% respectively; overall, p?=?0.004). Cox proportional hazard analysis showed that a small BSA was an independent predictor of postoperative mortality (hazard ratio?=?0.22, 95% confidence interval?=?0.05–0.97, p?<?0.04). These findings highlight the adverse impact of a small BSA on outcomes after CF-LVAD implantation.     

B-type natriuretic peptide levels and continuous-flow left ventricular assist devices

We postulated that postoperative B-type natriuretic peptide (BNP) levels would be reflective of the degree of hemodynamic support rendered by various pump speeds settings (RPM) of continuous-flow left ventricular assist devices (LVADs). Twenty LVAD patients were evaluated prospectively (Jarvik 2000: n = 9, HeartMate II: n = 11). The mean age was 57.7 ± 14.9 years, and 14 were male. B-type natriuretic peptide levels were drawn while the patients were supported on LVADs at variable RPM settings. The RPM settings were correlated with the changes in BNP levels. Eleven patients underwent LVAD implantation for a lifelong support while the rest were as a bridge therapy to transplantation. Four patients required LVAD change out for various causes of pump failure. Postoperative BNP levels decreased dramatically with the initiation of LVAD support. The levels correlated inversely with the degree of hemodynamic support rendered at various RPM settings of the HeartMate II (p < 0.001). Overall, BNP levels decreased significantly in 2 days after RPM increase. We observed a significant inverse correlation between the postoperative BNP levels and the degree of LVAD support. The effective LVAD support seems to result in a marked reduction in BNP levels, and monitoring serial BNP levels may be helpful in managing patients supported on continuous LVAD.     

A case of late-onset right ventricular failure after implantation of a continuous-flow left ventricular assist device

Postoperative right ventricular failure is usually apparent perioperatively or soon after left ventricular assist device insertion. Here, we report a case complicated by right ventricular failure that manifested 3 weeks after HeartMate II implantation. This case is also unique because the postoperative right ventricular failure was progressive over the years. We discuss how the smaller size of the left ventricle and untreated tricuspid regurgitation contributed to the development of right ventricular failure in this case.     

Racial differences in patients with left ventricular assist devices

We examined clinical outcomes based on ethnicity in patients undergoing left ventricular assist device (LVAD) implantation. We hypothesized that treatment in a specialized, comprehensive heart failure program results in similar survival between African Americans and whites. We retrospectively reviewed patient data implanted with HeartMate II (HM-II) LVAD over 2 years. There were 79 patients: 34 (43%) whites, 33 (42%) African Americans, and 12 (15%) patients belonging to other ethnicities there was no difference in demographics. The etiology of cardiomyopathy was more commonly ischemic in white patients compared to nonischemic in African American patients (p = 0.01). The mean left ventricular ejection fraction was 22.21 ± 10.66% in African American patients and 15.21 ± 5.54% in white patients (p = 0.008). The left ventricular end-diastolic (p = 0.06) and end-systolic (p = 0.03) diameters were greater in white patients compared to African American patients. Hypertension was seen in 79% of African American patients compared to 56% in white patients (p = 0.07). Survival by Kaplan-Meier analysis revealed an unadjusted survival advantage in African American patients (p = 0.04 by log-rank test), but this survival advantage was lost in multivariable Cox regression analysis after adjustment for other covariates. There was no difference in readmissions (p = 0.36). In patients with advanced heart failure undergoing HM-II LVAD implantation, African American patients had a similar survival and no difference in readmissions when compared with white patients despite significant differences in baseline clinical characteristics.     

Granulomatous myocarditis in severe heart failure patients undergoing implantation of a left ventricular assist device

BackgroundGranulomatous myocarditis may develop into cardiomyopathy and severe congestive heart failure that requires implantation of a left ventricular assist device (LVAD).MethodsLeft ventricular (LV) core samples were collected from 177 patients with severe heart failure at the time of LVAD implantation, and samples were histologically examined and graded for severity of hypertrophy and fibrosis. Granulomatous myocarditis incidentally seen in a subset of samples was characterized by staining and culturing for mycobacteria and fungi. Various clinical parameters in these patients were analyzed.ResultsOf the 177 LV core samples examined, 6 (3.4%) showed nonnecrotizing granulomatous inflammation in the myocardial wall. Stains and cultures for mycobacteria and fungi were negative. All six patients [three women, three men; five African American, one Asian; mean age, 52±9 years (range, 41–61 years)] had arrhythmias and required an automatic implantable cardioverter defibrillator. Before LVAD implantation, the patients' mean cardiac index was 1.8±0.4 l/min/m²; cardiac output, 2.9±0.6 l/min; and ejection fraction, 20±2%. One year after LVAD implantation, one patient had undergone heart transplantation. At 2 years, a second patient was transplanted, and one died. At 3 years, a third patient was transplanted and died postoperatively; two patients remained on support. No clinical evidence indicated involvement of other organs or recurrence in the transplanted patients.ConclusionThe incidental diagnosis of granulomatous myocarditis in our patients indicates that histological study of LV core samples in patients who undergo LVAD implantation may contribute to the diagnosis and be a consideration in the management of the underlying cause of heart failure.     

Effect of alteration in pump speed on pump output and left ventricular filling with continuous-flow left ventricular assist device

Third-generation continuous-flow left ventricular assist devices (LVAD) provide reduced pulsatility flow. We examined the safe working range for LVAD pump speed and the effect on pump output and cardiac function in 13 stable outpatients with VentrAssist-LVAD (Ventracor Ltd, Australia). Pump speed was decreased from a baseline mean of 2,073 ± 86 revolutions per minute (RPM, with corresponding mean flow of 5.59 ± 1.18 L/min, mean ± standard deviation) to an average low-speed of 1,835 ± 55 RPM (corresponding flow 4.68 ± 0.99 L/min) and up to high-speed of 2,315 ± 66 RPM (corresponding flow 6.30 ± 1.29 L/min). There was a strong linear relationship between alteration in speed and flow rates (r(2) = 0.89, p < 0.00001) but marked interpatient variation. Downward titration to preset minimum 1,800 RPM was achieved in 9/13 (69%) and upward titration to the preset maximum 2,400 RPM was achieved in 4/13 (31%). Upward titration was stopped due to ventricular suction or nonsustained ventricular tachycardia (VT) in 4/13 (31%). Ventricular suction or VT (in 4/13) tended to be more common in patients with poor right ventricular (RV) function (p = 0.07). In summary, pump flow is stable within a relatively small speed range and should not be altered without close monitoring due to variation in response between patients, particularly with concomitant RV impairment.     

Tricuspid valve repair in patients supported with left ventricular assist devices

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

Quantification of interventricular dyssynchrony during continuous-flow left ventricular assist device support

Journal of Artificial Organs - Under continuous-flow left ventricular assist device (CF-LVAD) support, the ventricular volume change and cardiac cycle between the left ventricle (LV) and right...     

Effects of implantation on the mechanical properties of the polyurethane diaphragm of left ventricular assist devices

Tensile properties of blood pump diaphragms made from a segmented polyether polyurethane (Toyobo TM5) were studied after implanting in goats for variable periods of time up to 72 days. The implantation decreased the tensile strength and ultimate elongation at break, while the elastic modulus increased very slightly. These changes in the strength and ductility were primarily caused by the contact of material with blood rather than by the mechanical fatigue of material. Mechanical stability was greatly improved by removing residual oligomers from the material by a refining procedure. The refined polyurethane has characteristics favourable for blood pump applications.     

Retrospective hemolysis comparison between patients with centrifugal biventricular assist and left ventricular assist devices

Little is known about the hemolysis rate in the case of concomitant implantation of two continuous flow pumps for the treatment of biventricular heart failure. We present a retrospective study comparing the hemolysis parameters in patients supported with one implantable centrifugal pump of the type HeartWare HVAD used as a left ventricular assist device (LVAD) and with two pumps as a biventricular assist device (BiVAD). A total of 20 consecutive patients who received HeartWare BiVAD (n = 10) and LVAD (n = 10) support at our institution between September 2009 and September 2010 were examined. Hemolysis- and anemia-related parameters were analyzed after 2 weeks, 5 weeks, 3 months, and 6 months of support. Preoperative levels of hemoglobin, lactate dehydrogenase (LDH), and total bilirubin were similar in both groups. There were no differences in LDH, plasma-free hemoglobin (fHB), or total bilirubin levels postoperatively for up to 6 months. Only the haptoglobin level was lower in BiVAD recipients up to 3 months after surgery: 2nd week (63.5 [range: 8-237] mg/dl vs. 151 [range: 11-263] mg/dl, p = 0.05), 5th week (67 [range: 8-196] mg/dl vs. 215 [range: 56-292] mg/dl, p = 0.046), and after 3rd month (42 [range: 8-205] mg/dl vs. 220 [range: 157-256] mg/dl, p = 0.048). Our retrospective analysis of BiVAD HeartWare and LVAD HeartWare recipients showed a lack of a clinically important degree of hemolysis when two centrifugal HeartWare pumps are used for biventricular support.     

Experience with noncardiac surgery in destination therapy left ventricular assist devices patients

Continuous flow left ventricular assist devices (CF-LVAD) are increasing the life expectancy of patients with advanced heart failure, with these patients undergoing more noncardiac operations after implantation. The purpose of this study was to determine the safety of noncardiac operations in destination therapy CF-LVAD patients. In a retrospective study of 110 CF-LVAD patients, we reviewed 36 patients who underwent 63 noncardiac operations 315.1 ± 333.5 days after LVAD placement. Fifty-four (84%) operations were elective and 10 were emergent. The mean age of the cohort was 61.4 ± 11.4 years, with the majority (81%) being men. Most patients (n = 24, 38%) underwent total abdominal operation. Of the 36 patients in the study, 23 (63.8%) patients required one surgical procedure, and 13(36.1%) patients underwent more than one procedure. Six critically ill patients (16%) of 37 expired within 30 days after emergent operation. Our study demonstrates overall good clinical outcomes with minimal intraoperative complications in LVAD patients undergoing noncardiac surgeries, except an increased propensity for intra- and postoperative transfusion of blood products because of complex coagulopathies.     

Prediction of aortic valve regurgitation after continuous-flow left ventricular assist device implantation using artificial intelligence trained on acoustic spectra

Significant aortic regurgitation (AR) is a common complication after continuous-flow left ventricular assist device (LVAD) implantation. Using machine-learning algorithms, this study was designed to examine valuable predictors obtained from LVAD sound and to provide models for identifying AR. During a 2-year follow-up period of 13 patients with Jarvik2000 LVAD, sound signals were serially obtained from the chest wall above the LVAD using an electronic stethoscope for 1 min at 40,000 Hz, and echocardiography was simultaneously performed to confirm the presence of AR. Among the 245 echocardiographic and acoustic data collected, we found 26 episodes of significant AR, which we categorized as “present”; the other 219 episodes were characterized as “none”. Wavelet (time–frequency) analysis was applied to the LVAD sound and 19 feature vectors of instantaneous spectral components were extracted. Important variables for predicting AR were searched using an iterative forward selection method. Seventy-five percent of 245 episodes were randomly assigned as training data and the remaining as test data. Supervised machine learning for predicting concomitant AR involved an ensemble classifier and tenfold stratified cross-validation. Of the 19 features, the most useful variables for predicting concomitant AR were the amplitude of the first harmonic, LVAD rotational speed during intermittent low speed (ILS), and the variation in the amplitude during normal rotation and ILS. The predictive accuracy and area under the curve were 91% and 0.73, respectively. Machine learning, trained on the time–frequency acoustic spectra, provides a novel modality for detecting concomitant AR during follow-up after LVAD.

     

Regenerating a ventricular cavity during left ventricular assist device implantation

Journal of Artificial Organs - Ten months after an ineffective percutaneous coronary stent placement, a 53-year-old patient was rehospitalized with NYHA functional class IV congestive heart...     

A novel counterpulse drive mode of continuous-flow left ventricular assist devices can minimize intracircuit backward flow during pump weaning

Bridge to recovery has become a major goal after left-ventricular-assist-device (LVAD) implantation thanks to recent development in adjunctive therapies. Precise assessment of native heart function under minimum LVAD support is the key for successful LVAD explantation. However, weaning of centrifugal LVADs normally generates diastolic intracircuit backward flow. This retrograde flow may become excessive load for the native heart during off-pump test. The flow itself is an inevitable characteristic of centrifugal pumps. Therefore, evaluating this retrograde flow in vitro is of considerable significance, even if its amount is different from that in clinical settings. The purpose of this study was to assess diastolic backflow of continuous-flow centrifugal LVADs in a mock circulation model. A centrifugal LVAD (EVAHEART, Sun Medical Technology) was installed in a mock circulation model by the left ventricle uptake and the ascending aortic return. Pump flow was measured at the pump rotational speed of 1000, 1500, 2000, and 2500 rpm, and pulse rate of the virtual native heart was varied to 60, 90, and 120 beats/min. After data collection, pump flow was integrated, and forward and backward intracircuit flow were calculated. As a result, nonphysiological reverse flow of approximately 2.0 L/min exists at the rotational speed, providing 0 L/min mean pump flow. An ideal off-test trial condition should be realizing both ±0 L/min pump flow and no intracircuit backward flow at the same time. We are developing a novel EVAHEART drive mode that can change its rotational speed in synchronization with cardiac cycle with the aim of controlling this retrograde flow with the new drive mode and creating an ideal off-test condition.     

Readmissions after continuous flow left ventricular assist device implantation

Continuous flow left ventricular assist device (CF-LVAD) therapy has improved the survival of patients with advanced heart failure. However, the readmission rate of CF-LVAD patients is still relatively high. A total of 90 patients who received CF-LVADs between April 2011 and March 2016 at our institute and were discharged home were analyzed retrospectively. They were followed up through March 2017. Clinical data, including frequency, length and etiology of readmission, were obtained from medical records. The mean observation period after initial discharge was 713 ± 322 days. In total, 73 patients (81%) had 236 readmissions, 214 unplanned and 22 planned. The overall and unplanned readmission rates were 1.34 and 1.22 per patient-year, respectively. The rate of freedom from unplanned first readmission at 1 year after initial discharge was 39%. The median interval between the previous hospital discharge and first and second readmissions was 311 and 213 days, respectively (log-rank test, p = 0.117). The rate of readmission after more than three readmissions was significantly higher than that of first or second readmission (log-rank test, p < 0.001). The most common etiology of readmission was driveline infection (DLI) (36%), followed by stroke (9%). The median length of hospital stay due to DLI was 23 days. The patients with repeated unplanned readmissions had significantly lower EuroQol 5 dimensions questionnaire utility score than those with no or just one readmission. Readmission was common in CF-LVAD patients, and the most common etiology of readmissions was DLI. The interval to the next readmission seemed shorter for patients with repeated readmissions.     

Survival outcomes of patients with giant cell myocarditis bridged by ventricular assist devices

Giant cell myocarditis is a highly lethal disorder characterized by rapidly progressive congestive heart failure. The aim of this study was to describe the clinical course of patients with giant cell myocarditis who received a ventricular assist device. Patients with giant cell myocarditis were identified from the Multicenter Giant cell Myocarditis Registry. Bridging to cardiac transplantation in the giant cell myocarditis patients who received a ventricular assist device was compared with bridging in the general population of heart failure patients, as reported in the literature. Median posttransplantation survival for patients with giant cell myocarditis who received and did not receive ventricular assist devices was calculated by the Kaplan-Meier method and compared with use of the log-rank test. Nine patients with giant cell myocarditis who received ventricular assist devices were identified. Seven patients survived to transplantation, four were alive 30 days posttransplantation, and two survived to 1 year. The rate of successful bridging to transplantation in seven of nine patients (78%) is similar to that reported for other ventricular assist device recipients. Posttransplantation survival of 57% (4 of 7) at 30 days and 29% (2 of 7) at 1 year was significantly lower compared with 93% 1-year survival of the 30 patients with giant cell myocarditis who did not receive ventricular assist devices before transplantation (p<0.001). Ventricular assist devices can be an effective bridge to transplantation for patients with heart failure caused by giant cell myocarditis. Although their posttransplantation survival was poor in our series, a few patients had long-term survival.